21 • Chapter 2. The Anatomy Of The Submandibular And The Parotid Glands • CHAPTER OUTLINE THE CLINICAL ANATOMY OF THE PAROTID REGION............................21 1. Regional Formation/ Classification........21 2. The Parotid Region...............................21 3. Conduction Pathways Of The Parotid Region..........................23 THE CLINICAL ANATOMY OF THE SUBMANDIBULAR TRIANGLE...........26 References...................................................28 THE CLINICAL ANATOMY OF THE PAROTID REGION The parotid gland has an exceptional posi tion under the major salivary glands. It is not only penetrated by major blood vessels and nerves of the head, it is also divided by a strong capsule, which somewhat limits an enlargement in case of inflammatory or spaceoccupying processes 1—5 . 1. Regional Formation/ Classification The parotid gland lies topographically in the parotideomasseteric region, which is defined superiorly by the zygomatic arch, posteriorly by the mastoid process, the tragus and the ex ternal auditory canal, inferiorly by the margin of the mandible and anteriorly by the front margin of the masseter muscle. A lamella of connective tissue divides the parotid gland into two distinctive layers, superficial and deep, through which the facial nerve branches run. Medially the parotideomasseteric region merg es with the retromandibular fossa (Regio faciei parot.), which contains soft connective tissue, and passes medially into the peripharyngeal space and dorsally into the infratemporal fossa. The parotid gland extends into the retromandib ular fossa up to the fan of muscles arising from the styloid process, and halts before reaching the pharynx wall (Fig. 21). The ventral extension of the parotideomas seteric region merges gradually with the buc cal region. The later extends from the anterior margin of the masseter muscle to the fascial muscles and is mostly filled with the corpus adiposum buccae (buccal pad of fat), the Bichat’s fat plug. 2. The Parotid Region The parotid gland is roughly triangular in shape. The superior margin generally lies a fin ger width (1.5—2 cm) beneath the inferior mar CHAPTER 2 The Regional Anatomy Of The Submandibular And The Parotid Glands Johannes W. Rohen Johannes Zenk 22 • Modern Management Preserving the Salivary Glands • gin of the zygomatic arch. The gland borders dorsally on the mastoid process, the tragus of the outer ear and the sternocleidomastoid mus cle whose superficial fascia merges with the body the gland. The parotid gland forms infe riorly a triangular lobe (Lobus colli), which extends beyond the margin of the mandible down to the platysma. Within the gland a superior and inferior duct converge to produce the tough excretory duct (parotid duct) which leaves the gland, and follows a course over the masseter muscle to wards the buccal cavity, often accompanied by gland tissue. This excess tissue frequently forms a lobe of gland (accessory parotid gland), which varies in size and may accompany the excreto ry duct to its orifice. The parotid duct reflects at the anterior margin of the masseter muscle at an angle of 90° inwards and then proceeds reflecting anteriorly at the groove of the cor pus adiposum buccae until it reaches the oral vestibule at the height of the second upper molar. There it penetrates the buccinator mus cle and builds a small papilla at the mucosa (buccal salivary papilla). Frequently many small glands can be found at the orifice (buc cal glands), which belong functionally to the mucosa. Typically the course of the parotid duct is horizontal, running approximately 2 cm below the zygomatic arch and parallel to a pro jectionline, from the onset of the earlobe to the carmine of the upper lip. The parotid duct is about 5—6 cm long and the diameter varies between 0.5 and 2.3 mm. In the vicinity of the gland and the orifice the di ameter averages 1.4 mm, narrowing to approx imately 1.2 mm as the duct penetrates the buc cinator muscle. The narrowest point is the Fig. 21. Parotideomasseteric region and buccal region (lateral view). (J.W. Rohen, Ch. Yokochi, E. LütjenDrecoll: Color Atlas of Anatomy. A Photographic Study of the Human Body, 6 th Edition. SchattauerVerlag, Stuttgart, 2006) 7 6 5 4 3 2 1 18 17 16 15 14 13 12 11 10 9 8 10 9 8 7 6 5 4 3 2 1 1 — N. auriculotemporalis and A. temporalis superf.; 2 — Rr. temporofaciales n. VII; 3 — Tragus; 4 — A. transversa faciei; 5 — Gl. parotidea; 6 — Ductus parotideus; 7 — M. masseter; 8 — N. auricularis magnus; 9 — R. colli n. VII; 10 — Erbpoint, where the cutaneous branches of cervical plexus appear to sup ply the skin of the neck and the scalp 1 — N. auriculotemporalis and V. temporalis superf.; 2 — A. tem poralis superf.; 3 — N. facialis (N. VII); 4 — Pars temporofacia lis n. VII; 5 — A. carotis ext. and V. retromandibularis; 6 — Pars cervicofacialis n. VII; 7 — Glandula parotidea; 8 — M. orbicu laris oculi; 9 — A. zygomaticoorbitalis; 10 — Arcus zygomaticus; 11 — Mm. zygomatici; 12 — A. transversa faciei; 13 — Ductus parotideus; 14 — Rr. zygomatici and Rr. buccales n. VII; 15 — M. masseter; 16 — A. and V. facialis; 17 — R. marginalis man dibulae n. VII; 18 — R. colli n. VII 23 • Chapter 2. The Anatomy Of The Submandibular And The Parotid Glands • Fig. 22. The horizontal section through the parotid fossa. The parotid gland does not enter the peripharyn geal space (with its deep part) and does not reach the muscles that arise from the styloid process (stylopha ryngeal, stylohyoidal, styloglossal muscle) (J.W. Rohen, Topographische Anatomie, 10. Aufl., Schattauer Ver lag, 2000) orifice itself. The diameter at this point is usu ally 0.5 mm or less (J. Zenk et al., 1998). The parotideomasseteric fascia is very dense and consists of various types of connective tis sue, mainly collagenfibers. It adheres strongly to the capsule of the gland, protracting into the gland tissue as lamella and forming lobes which make it impossible to dissect the gland from its capsule. The capsule of the gland also adheres to the fascia of the neighboring muscles partic ularly the masseter and the sternocleidomas toid muscle. An exception is the cervical lobe (Lobus colli) which has no connections to the fascia of the nearby muscles (stylohyoid muscle, poste rior belly of the digastric muscle and platysma). At the retromandibular fossa, the gland is lim ited by soft lamellae of connective tissue from the peripharyngeal space, the fasciae of the stylohyoidal, stylopharyngeal and styloglossal muscles, and strands of vessels and nerves run ning through this region (external carotid ar tery, internal jugular vein, cranial nerves, lym phatic vessels) (Fig. 22). 3. Conduction Pathways Of The Parotid Region 3.1. Nerves The sensory perception of the skin covering the parotid fossa originates from the great au ricular nerve which rises perpendicular, from the source at the cervical plexus, to the anteri or of the auditory canal where it then fans out over the parotid gland. The auriculotemporal nerve arises from the mandibular division of the trigeminal nerve, en ters the parotid fossa behind the neck of the mandible and leaves it at the superior margin of the parotid gland; it then follows a vertical path together with the superficial temporal ar tery and vein towards the parietal skin. The most important nerve of the region is the facial nerve (N. VII), which enters the pa rotid fossa where it leaves the stylomastoidal foramen and moves ventrically in a line which can be drawn from the external auditory canal to the mandibular angle. The nerve then di vides into a trunk that runs inferiorly (cervi calfacial part) and a trunk that reflects ante rosuperiorly (temporalfacial part), laterally crossing the large vessels proceeding through the gland (external carotid artery and retro mandibular vein). The exit point of the facial nerve from the stylomastoid foramen can easi ly be defined using the internal projection of the tragus as “pointer”. The exit point usually lies centrally between the “pointer” and the stylohyoidal process. The subdivision of the facial nerve into the two mainbranches can be defined according to Eyries (1972) as follows; 9 8 7 6 5 4 3 2 1 19 18 17 16 15 14 13 12 11 10 1 — Papilla salivaria buccalis; 2 — Mandibula; 3 — Tonsilla pa latina; 4 — Pharynx; 5 — Spatium peripharyngeum; 6 — Proc. styloideus; 7 — A. carotis int.; 8 — N. vagus (X); 9 — N. glos sopharyngeus (X) and N. hypoglossus (XIII); 10 — V. jugularis int. 11 — M. buccinator; 12 — Ductus parotideus; 13 — M. mas seter; 14 — M. pterygoideus med. 15 — Fascia parotidea; 16 — N. facialis (VII); 17 — V. retromandibularis; 18 — A. carotis ext.; 19 — Parotid gland 24 • Modern Management Preserving the Salivary Glands • the first line runs from the traguspointer to the mandibular angle (TG in Fig. 23) the second from the mastoidal process to the middle of the mandibular ramus (MM in Fig. 23). The in tersection of these two lines (F in Fig. 23) marks in about 70% of cases the point in which the facial nerve divides within the parotis. The superior mainbranch of the facial nerve divides rapidly into relatively thin, closely ap proximated temporal and frontal branches, which leave the parotid gland below the zygo matic arch, over which they then cross diago nally to reach the mimetic muscles near the line of the hair, for which they are responsible. The distance from the external ear and tra gus varies, but is usually under 1.5—2 cm (M.E.Wigand et al., 1997) (Fig. 24). In or der to avoid injury to the Facial nerve one should choose an incision which preserves the subcutaneous fatpad lying laterally to the tem poral fascia. The two main branches, and the finer branches of the facial nerve; which anastomose with one another to form a coarsely meshed network (parotid plexus); lie within the same plane in the parotid gland and divide the gland into two layers. The superficial layer is relative ly thin, the deeper layer together with the ret romandibular fossa portion of the gland takes much more space. The temporalfacial part of the VII nerve divides immediately into numer ous branches, which run diagonally to the su perior margin of the parotid gland where they exit at the parotid fossa. The branches reach ing the farthest cranially are the temporalfron tal branches which cross over the zygomatic arch and then approach the underside of the au ricular anterior muscle, the frontal belly of the occipital frontal muscle and the orbicular mus cle of eye (superior parts until the palpable fis sure), which they innervate (somatomotoric). A second group builds the zygomatic branches, which run at the height of the zygomatic arch and supply the inferior part of the orbicular muscle of the eye and zygomatic muscles. The first divisions of the inferior main facial branch (cervicalfacial part) are the buccal branches of the facial nerve, which lie near the masseter muscle, and irradiate inferiorly at the Fig. 23. The localization of the main facial trunk and its point of bifurcation into the two main branches as described from Eyries (M.E. Wigand et al., 1997) TG F MM Fig. 24. The path of the temporalfrontal branches of the facial nerve in the preauricular region. Marked are the variable pathways of the temporal (T) and the frontal (F) branches. Two dimensions where measured (a = distance between lateral cantus and superior mar gin of auricle, b = distance between lateral cantus and tragushelix notsch) (M.E. Wigand et al., 1997) mimetic muscles of the inferior facial region (orbicular and buccinator muscles, and levator muscle at the angle of mouth). The superior branch of this fan. shaped system, also known a b T F 25 • Chapter 2. The Anatomy Of The Submandibular And The Parotid Glands • as superior buccinator muscle, generally runs absolutely parallel to the parotid duct. Howev er variations of the branching pattern of the facial nerve in the anterior facial region are very frequent. The marginal mandibular branch is the last division of the inferior facialbranch which leaves the body of the gland at the margin of mandible, and then follows the ramus of man dible anteriorly to reach and innervate the fa cial muscles in mandibular region. The cervi cal division of the facial nerve surfaces at the inferior margin of the cervical lobe of the pa rotid gland and proceeds downwards, connect ing with the cervical cutaneus nerve of the cer vical plexus. They then surface together with the greater auricular nerve at the “Erbpoint” of the cervical ansa. The cervical branch is par tially responsible for the innervation of the platysma. The Jacobson’s anastomosis of the glossopha ryngeal nerve (N. IX) is responsible for the para sympathetic (excretory) innervation of the pa rotid gland. The tympanic branch of the gloss pharyngeal nerve forms the tympanic plexus in the tympanic cavity giving rise to the minor pet rosal nerve. The lesser petrosal nerve leaves the plexus and run through the sphenopetrosal fis sure to the auricular ganglion, where the pregan glionic axons are switched to postganglionic, parasympathetic fibers for the parotid gland. Fine nerves emerge from the auricular gan glion, positioned at the medial site of the man dibular nerve (third branch of the trigeminal nerve), and attach to the auriculotemporal nerve (branch V3), which enters the parotid fossa im mediately posterior to the neck of the mandible, and joins the superficial temporal artery and vein. From the auriculotemporal nerve emerge, within the parotid fossa, branches to the facial nerve, with which parasympathetic, excretory axons of the postganglionic nerves of the auric ular ganglion reach the parotid gland. The facial nerve has herewith an influence on the excreto ry function of the gland. Small motor branches emerge from the fa cial nerve, between exiting from the stylomas troid foramen and entering the parotid fossa, and innervate the stylohyoid and styloglossus muscles (which belong to the second pharyn geal arch), the posterior belly of the digastric muscle, the auricular muscles (belonging to the mimetic muscles) and the occipital belly of the occipitofrontal muscle. These branches run di rectly under the base of the skull, at the root of the styloid process in the depths of the ret romandibular fossa. The facial nerve branches which innervate the mimeticmuscles of the facial regions leave the nerve stem within the parotid fossa. 3.2. Vessels The external carotid artery enters the parot id fossa from the carotid triangle, which lies di rectly under the fossa, and runs medially to the muscles arising from the styloid process (sty lohyoid muscle, posterior belly of the digastric muscle) but laterally from the stylomandibular ligament. It attaches within the parotid gland to the retromandibular vein. The retromandib ular vein emerges from the confluence of the superficial temporal vein anteriorly, and the veins of the pterygoid plexus which come from the region of the deep masticatory muscles (Figs. 2.1 and 2.2). The external carotid artery lies close to the stylomandibular ligament; thus pulling the mandible lightly forward and strain ing the ligament provides a stable base when searching for the artery. The external carotid artery divides approximately in the middle of the parotid gland into the superficial temporal artery and the maxillary artery. The temporal artery runs near the external auditory canal towards the temporal region, ac companied by the auriculotemporal nerve and the superficial temporal vein. The transverse fa cial artery (branch of the temporal artery) branches anteriorly at the height of tragus and neck of mandible, it supplies the anterior sec tion of the parotid gland and after leaving the gland runs parallel to the parotid duct, where if necessary it also supplies accessory parotid gland tissue (Fig.21). The transverse facial artery may in some cases be a branch of the external carotid artery itself, which is sufficient enough to take over the supply of regions that are normally supplied from the facial artery. 26 • Modern Management Preserving the Salivary Glands • Fig. 25. Retromandibular region. The parotidgland is removed (J.W. Rohen, Ch.Yokochi, E. Lütjen Drecoll, Color Atlas of Anatomy, 6. Aufl. Schattauer Verlag, Stuttgart, 2006) which are accompanied by the maxillary artery, into the retromandibular vein. The retromandibular vein usually runs with in the parotid gland lateral to the external ca rotid artery (Fig. 21, 22), from which it sep arates caudally and crosses laterally the muscles which arise from the styloid process, before exiting the parotid fossa at the front margin of the cervical lobe. It joins the facial vein at the angle of the mandible and empties into the jugular vein. The anatomy of the veins of the head varies greatly; therefore the descriptions given here are only an excerpt of the principles of the more common variants. The veins are usually accompanied by vari ous sized lymph nodes, which are grouped along the lymphatic routes. The nodes lying within the parotid gland are mainly in front of the exter nal auricle canal and are known as deep parotid lymph nodes, those lying outside the parotideo masseteric fascia are the superficial parotid lymph nodes. The preauricular lymph nodes and the submandibular nodes lie at the angle of the mandible and are easy to palpate. The lymph nodes of the parotid gland drain the lymph from the auricle (anterior part), the temporal region, the lateral part of the eyelid and the lateral face regions. They drain into the deep cervical lymph nodes, which are located at the anterior part of the internal jugular vein. THE CLINICAL ANATOMY OF THE SUBMANDIBULAR TRIANGLE The submandibular gland is located in the anterior cervical region in the submandibular triangle (Fig. 25 and 26). The boundaries of this triangular region are set by the anterior and posterior belly of the di gastrics muscle and the mandible, the floor is the mylohyoid muscle. The mylohyoid muscle does not completely fill the triangle, a gap re mains which functions as a connection to the oral cavity. The gap is limited medially by the The second largest branch of the external carotid artery is the maxillary artery, which runs horizontally behind the neck of the man dible to the retromandibular fossa, and leaves the parotid fossa, for the intratemporal fossa from where it supplies with its numerous branches the organs of the lower regions of the face. The extensive venous pterygoid plexus develops here and has many connections (anas tomosis) with the veins of the orbit, the cav ernous sinus through the skull base foramena, and with the veins of the dura mater and the regions of the face. Posteriorly the pterygoid plexus usually empties over the maxillary veins, 1 2 3 4 5 6 7 8 9 10 11 12 13 1 — N. auriculotemporalis and A. temporalis superf.; 2 — Pr. tem porofaciales n. VII; 3 — Transverse facial artery; 4 — N. facialis (VII); 5 — Ductus parotideus; 6 — M. masseter; 7 — Rr. zygo matici and buccales n. VII; 8 — V. retromandibularis; 9 — A. fa cialis; 10 — R. marginalis mandibulae; 11 — R. colli n. VII; 12 — N. auricularis magnus; 13 — Gl. submandibularis 27 • Chapter 2. The Anatomy Of The Submandibular And The Parotid Glands • Fig. 26. Submandibular triangle. A. Superficial dissection. B. Deep dissection. (J. W. Rohen, Ch. Yokochi, E. LütjenDrecoll, Color Atlas of Anatomy, 6. Aufl. Schattauer Verlag, Stuttgart, 2006) A B hypoglossal muscle, which radiates into the tongue. The excretory duct of the submandi bular gland enters the oral cavity through this gap. The excretory duct is in its complete length surrounded by gland tissue, partly from the submandibular and partly from the sublin gual gland. As it reaches the entrance of the oral cavity the size of the angle varies between 24 and 178 degrees. 1–5 The diameter of the ex cretory duct is 1.5 mm and the length about 5— 6 cm. 5 The hypoglossal nerve and the lingual vein travel along the path of the excretory duct. A 1 — A. submentalis; 2 — M. mylohyoideus; 3 — Venter ant. m. digastrici; 4 — A. and V. facialis; 5 — Gl. submandibularis; 6 — N. hypoglossus (XII) and A. lingualis; 7 — M. stylohyoideus; 8 — A. carotis ext. and A. thyroidea sup. B 1 — M. mylohyoideus; 2 — N. lingualis; 3 — N. hypoglossus (XII); 4 — M. geniohyoideus; 5 — A. and V. facialis; 6 — Gl. subman dibularis; 7 — Ductus submandibularis; 8 — A. carotis ext. and A. thyroidea sup. 4 3 2 1 8 7 6 5 7 6 5 4 4 3 2 1 8 28 • Modern Management Preserving the Salivary Glands • References l.Becker W, Haubrich J, Seifert G. Krankhei ten der Kopfspeicheldriisen in Berendes J, Link R, Zollner F (1978) HalsNasenOhren heilkunde in Praxis und Klinik Band 3, Thi eme Verlag, Stuttgart 12.01—12.50. 2.Drage NA, Wilson RF, McGurk M. The genu of the submandibular duct is the angle sig nificant in salivary gland disease? Dentomax illofac Radiol 2002; 31:15—8. 3.Rohen JW. Topographische Anatomie des Menschen (1984) Schattauer Verlag Stut tgart, New York. The lingual nerve (N.V3) curves laterally and a slightly cranial from the hypoglossal muscle and forms the submandibular ganglion at the level of the musclegap. The lingual artery en ters the floor of the mouth medial to the hypo glossal muscle in the vicinity of the hyoid bone. The anatomy of the region clarifies why in fections of the oral cavity easily extend into the connective tissue at the posterior margin of the mylohyoid muscle. The remaining funnel shaped region is filled almost entirely with the submandibular gland, which is divided into the body and the uncinate process, the latter lies over the mylohyoid muscle in the floor of the mouth and borders to the anterior on the sub lingual gland. The gland is enclosed by a dense capsule and contains a great number of Lymph nodes (submandibular Lymph nodi) and a ca nal for the facial artery. At this point a small branch, to supply the gland, separates from the strongly twisted facial artery together with the submental artery, which accompanied by the mylohyoid nerve, travels anteriorly close to the mandible. A deep lying marginal mandibular branch of the facial nerve may lie directly over the submandibular gland capsule. The parasympathetic excretory innervation of the submandibular gland runs via the inter medial nerve, the parasympathetic part of the facial nerve, and the chorda tympani, through the petrotympanic fissure via the lingual nerve to the submandibular ganglion. At this point the synapse to postganglionic fibres takes place. The sympathetic innervation is supplied via the sympathetic trunk of the neck, the superior cervical ganglion in the external carotid plex us together with the facial and lingual artery of each particular gland. The apex of the submandibular gland may reach the tonsillar region. The sublingual part of the gland lying over the floor of the mouth (unc inate process or sublingual process) lies under the medial surface of the sublingual gland. The later lies in a sub mucosal plane in the oral cav ity on the mylohyoidal muscle and forms the sublingual fold at the floor of the mouth. The lateral section of the gland consists of about 40—50 singleglands, each of which has its own excretory duct (minor sublingual duct) discharging into the sublingual fold. The fron tal part of the gland includes a large portion of gland tissue whose excretory duct opens, sepa rately or together with that of the submandib ular gland, into the caruncula sublingualis. The orifices of the larger salivary glands contain tough elastic connecting tissue though no mus cle. The recurring postulated theory of an ac tive sphincter system could not be confirmed. 4.Teymoortash A, Ramaswamy A, Werner JA. Is there evidence of a sphincter system in Wharton’s duct? Etiological factors related to sialolith formation. J Oral Sci 2003; 45:233—5. 5.Zenk J, Zikarsky B, Hosemann WG, Iro H. The diameter of the Stenon and Wharton ducts. Significance for diagnosis and thera py. HNO. 1998; 46:980—5. 29 • Chapter 3. Diagnostic And Imaging Methods • CHAPTER OUTLINE PLAIN FILM RADIOGRAPHY...........................30 SIALOGRAPHY..............................................32 SONOGRAPHY OF THE LARGE SALIVARY GLANDS.......................................................34 THE PAROTID GLAND...................................34 THE SUBMANDIBULAR GLAND.....................36 THE SUBLINGUAL GLAND.............................37 PATHOLOGIC FINDINGS...............................37 ACUTE SIALADENITIS...................................37 CHRONIC SIALADENITIS...............................40 LYMPHNODE ENLARGEMENTS.....................44 CYSTIC TUMOURS........................................46 SIALOLITHIASIS............................................46 SIALADENOSIS.............................................49 BENIGN EPITHELIAL TUMOURS OF THE SALIVARY GLANDS...........................49 BENIGN NONEPITHELIAL TUMOURS OF THE SALIVARY GLANDS...........................52 MALIGNANT TUMOURS OF THE SALIVARY GLANDS.......................................................53 SUMMARY....................................................55 COLOUR DOPPLER SONOGRAPHY OF SALIVARY GLANDS..................................55 COMPUTED TOMOGRAPHY AND MAGNETIC RESONANCE IMAGING.......57 SCAN TECHNIQUES AND PROTOCOLS FOR CT........................................................58 SCAN TECHNIQUES AND PROTOCOLS FOR MRI......................................................58 T1WEIGHTED IMAGING................................59 T2WEIGHTED IMAGING................................59 FAT SUPPRESSION.......................................59 STANDARD SCAN PROTOCOL......................59 IMAGING OF BENIGN LESIONS OF THE SALIVARY GLANDS........................................60 MALIGNANT LESIONS OF THE SALIVARY GLANDS.......................................................61 CT AND MRI OF INFLAMMATORY DISEASE OF THE SALIVARY GLANDS...........................63 SCINTIGRAPHY.............................................64 SIALOENDOSCOPY.......................................64 References...................................................65 While inflammatory and neoplastic diseas es of the glands are well diagnosed, we put a special emphasis on diagnosis of obstructive diseases of the salivary glands. A history and clinical examination will be highly suggestive in cases of obstruction in one of the major salivary glands. A classic present ing symptom of obstruction is that of recurrent CHAPTER 3 Diagnostic and Imaging Methods Jackie Brown Holger Greess Johannes Zenk Oded Nahlieli 30 • Modern Management Preserving the Salivary Glands • swellings of the affected gland related to meals, known as mealtime syndrome. A sight or smell of food stimulates rapid production of increased quantities of saliva that is unable to pass quick ly through a compromised outlet. As a result the gland becomes engorged with saliva, often within minutes of tasting or smelling food, and then the swelling subsequently resolves over a period of several hours as the saliva drains slowly past the obstruction. The nature of the lesion preventing outflow is best identified by imaging. Visual scanning of submandibular, preauric ular and postauricular regions is the first step in assessing swelling and erythema. This is fol lowed by oral examination. Surgical magnifica tion loops (2.5—3.5) are very useful to improve visualization of the orifice of Wharton’s and Stensen’s ducts. The orifice may be red and edematous and appear as a papilla. Plaques or whitish secretions from the duct may represent frank infection. Sometimes a small stone can be found in the orifice, and the white—yellow co lour of a stone can be seen through the trans lucent mucosa. Bimanual palpation is particu larly important when examining the submandibular gland and duct. It helps to dif ferentiate the gland from adjacent lymph nodes, inferior to the gland, and to ascertain the pres ence of any firm mass in the takeoff of Whar ton’s duct from the hilum of the gland. For the parotid gland, manual palpation allows the sur geon to determine the consistency of the gland. One should also massage the gland to milk and inspect the saliva. Imaging plays a central role in diagnosis & management of salivary gland obstruction. Im aging should be used to — aid clinical diagnosis by confirming the presence of obstruction, — exclude other causes of salivary gland enlargement which are not related to obstruction, such as inflammatory & au toimmune conditions or tumours, — identify the cause of obstruction & dis tinguish between calculi formation, ob struction due to mucous plugs or due to the formation of ductal stenoses, — identify cases suitable for a minimally invasive approach, — play a central role in treatment planning, — guide treatment peroperatively, — monitor postoperative resolution. Imaging options in salivary gland obstruc tion have increased in number and sophistica tion in recent years and now include — Plain film imaging, — Sialography, — Ultrasound (Sonography), — Ultrasound Doppler (Colour Doppler Sonography), — Computed Tomography (CT), — Magnetic Resonance Imaging (MR), — Scintigraphy, — Sialoendoscopy. Some of these techniques are new, experi mental and have yet to establish a place in an investigative regimen. Others form the main stay of diagnostic imaging and these include sialography, ultrasound imaging, crosssectional imaging such as MR and scintigraphy. PLAIN FILM RADIOGRAPHY Plain radiographs are a simple and accessi ble method for identifying radiopaque calculi that represent the majority of submandibular stones (60—80%). The ductal stones are well demonstrated by a mandibular true occlusal to show the floor of the mouth while hilar stones may be seen on a panoramic view, an oblique lateral mandibular projection (particularly if the tongue is depressed) or a posterior oblique mandibular occlusal. This technique will be the most successful in identification of very small stones (2 mm or less) in the distal submandib ular duct besides sialendoscopy (Figs 31 A, B and 32). Plain radiographic examination of the parot id gland is less satisfactory since only 20—40% of parotid stones are radiodense. A posterio 31 • Chapter 3. Diagnostic And Imaging Methods • anterior view of the cheek, relaxed or distend ed with air, is the most likely examination to reveal a calculus. A tiny stone near the duct orifice may be demonstrated by a dental film placed inside the cheek (Fig. 33). A negative finding on plain film, however, cannot exclude a stone and further imaging is required. In conclusion, plain film imaging has a role in the initial diagnosis of stones, particularly in the submandibular gland, and in identifying small very distally placed calculi. Fig. 31. A — Lower true occlusal radiograph showing a small and lightly calcified submandibular duct stone (arrow). B — Lower oblique occlusal radiograph demonstrating 2 stones, one in the submandibular hilum (white arrow) and the other near the orifice of the duct (yellow arrow) A B Fig. 32. Submandibular stone on panoramic imaging 32 • Modern Management Preserving the Salivary Glands • SIALOGRAPHY This traditional contrast study was first de scribed by Carpy and Poirer in 1904. 1 Radio paque contrast is to be injected into the sali vary gland to demonstrate ductal architecture though this technique is limited to the parotid or submandibular glands since the sublingual glands normally lack a well developed main ductal system. During this study, the papilla and duct ori fice of the parotid or submandibular duct is to be identified first. The duct opening should be than instrumented to allow access and cannu lated with a bluntended catheter. Iodinebased radiopaque contrast is introduced through the salivary duct orifice and xray imaging under taken. This may be done in the form of static films or under fluoroscopy. The latter may be supplemented by digital subtraction sialogra phy. Introduction of contrast may be performed by hand injection, and it may be allowed to flow into the gland under hydrostatic pressure 2 or be injected by continuousinfusion pressure monitored technique. 3 The latter two tech niques allow the introduction of an average 0.5—1.5 ml of contrast in a more controlled manner that prevents overfilling of the gland and reduces discomfort. The pressuremoni tored technique further gives feedback on changes in pressure which can indicate an ob struction. The resolution of conventional plain film sialography is superior to any of the other im aging techniques 4, 5 and explains the dominance of this examination for demonstrating fine duct structures down to the tertiary salivary ducts and for detecting and localising tiny calculi. Isacsson et al found that the best method for di agnosing stones was sialography supplemented by plain films. 6 (Fig. 34 A). Furthermore this modality is most accurate for discriminating salivary stones from duct stenoses. 7 (Fig. 34 B) It is able to show both the position and length of a stenosis, and identify multiple duct stric tures (sialadochitis). Nahlieli advocates the use of Panorex in conjunction with the sialogram technique. Digital subtraction sialography allows dy namic assessment of contrast flow into the sali vary duct. This technique can detect the exact location of a salivary duct obstruction and ob servation of flow interruption allows an estima tion of the degree of obstruction (Fig. 35). Digital subtraction sialography has been found to give superior image quality to con Fig. 33. Small stone in the distal parotid duct seen on plain film and subsequently massaged to duct opening. (black arrow) 33 • Chapter 3. Diagnostic And Imaging Methods • Fig. 34. A — Sialogram of the right submandibular gland showing a stone (arrow) within the genu region of the main duct, at the entrance to the hilum. B — Sialogram of submandibular gland with stone (white arrow) and stricture (yellow arrow) superior to the stone A B ventional sialography and has shown higher sensitivity and specificity in the diagnosis of sialadenitis. 8 Sialography of the salivary duct orifices is the contrast instrumental mildly invasive pro cedure, occasionally causing discomfort. It has a recognised failure rate associated with diffi culties in cannulating of small ducts within the oral cavity. The procedure uses ionising radia tion and may displace small mobile stones near the duct orifice proximally into the gland and can disseminate acute infection. For this reason sialography is contraindicated during pregnan cy, acute sialadenitis and when a stone is very close to the duct opening. Allergy to iodine is a further contraindication, specifically to the use of conventional contrast media, but recent ly successful sialography with Gadolinium (an MR contrast agent) has been reported in io dinesensitive patients. 9 34 • Modern Management Preserving the Salivary Glands • Fig. 35. Fluoroscopic sialogram showing a stenosis (white arrow) of the parotid duct with subsequent proxi mal duct dilatation SONOGRAPHY OF THE LARGE SALIVARY GLANDS Three large salivary glands, the parotid gland, the submandibular gland, and the sub lingual gland are arranged in pairs and easily accessible to sonographic diagnosis due to their superficial location. Under normal conditions, the three large salivary glands exhibit similar homogeneous intermediate echogenicity with sharp borders 10, 11 . Small salivary glands become accessible to sonographic diagnosis only when pathological lesions are present (such as tumourous or neo plastic gland enlargement). The indications for sonographic examination include swelling in the region of the salivary glands primarily to xerostomy, and pain. 12 Examination by ultra sound enables the sonographers to verify whether masses are localized in, or merely ad jacent to, the inspected salivary gland. This distinction often cannot be made solely on the basis of a clinical examination 13 . Nowadays the use of high end ultrasound devices (Fig. 36 A) features a sonographic image like in an anatomy book. Resolution and penetration depth of ultrasound is dependent on the deployed frequency. The higher the fre quency leads to better the resolution but the penetration is worsened. For imaging of the sal ivary glands linear arrays with 7.5 MHz (5.0— 13.5 MHz) 14, 15 are most useful (Fig. 36 B). THE PAROTID GLAND The parotid gland can be easily assessed with the patient’s head turned sideways and hyperextended. As the first step of the sonographic examina tion, a transverse section is scanned, proceeding from the angle of the jaw up to a point slightly above the tragus. The longitudinal section is scanned next. The ultrasound probe must be adequately adapted to the surface of the skin by applying a sufficient amount of gel, particularly in the region of the angle of the jaw. 16 35 • Chapter 3. Diagnostic And Imaging Methods • In a transverse section, the parotid gland pre sents as a sharply bordered, homogeneous organ with intermediate echogenicity (Fig. 37). The gland can be clearly distinguished from subcu taneous fatty tissue. The anterior parts of the gland ride on the masseter muscle and can be differentiated from the buccal fatty tissue, which exhibits lower echogenicity, by the con traction and relaxation of the masticatory mus cles 17 . The posterior part of the gland is locat ed in the retromandibular fossa clearly demarcated anteriorly by the ascending ramus of the mandible and posteriorly by the sterno cleidomastoid muscle and the mastoid. Medio caudal to the lower pole of the parotid gland, the posterior belly of the digastric muscle and the internal carotid artery can be discerned. 18 The internal jugular vein and the retromandib ular vein, which is located in the glandular pa renchyma, can be visualized, particularly in a longitudinal section. In transverse planes dis tal to the retromandibular vein, the styloid pro A B Fig 36. A — Modern Ultrasound device (Siemens Sonoline Elegra ® ,Erlangen, Germany). B — Ultrasound probes. Two linear array applicators (5.1—13.5 MHz) 36 • Modern Management Preserving the Salivary Glands • Fig. 37. Sonoanatomy of the left parotid gland. Axial plane. UK = mandible MM = masster muscle GP = parotid gland MSCM = sternocleidoid muscle VJI = internal jugular vein MT = trapezoid muscle MD = posterior venter of digastric muscle VR = retromandibular vein cess is projected into the glandular parenchy ma and should not be confused with a sialolith. The facial nerve and non enlarged lymph nodes are not normally visible. However, with mod ern highresolution scanners, it is occasionally possible to obtain a sonographic image of the main efferent duct 19, 20 . THE SUBMANDIBULAR GLAND If the patient’s head is moderately extend ed, the submandibular gland can be sonograph ically examined without any problems. In the midline of the neck, the ultrasound scanner is moved in transverse orientation from the hyoid up to the horizontal ramus of the mandible. Occasionally, both submandibular glands can be imaged simultaneously. By shift ing the scanner to one side, parallel to the hor izontal ramus of the mandible, a clear image of the respective submandibular gland can be ob tained. The gel contact of the scanner to the skin has to be ensured here. Since it is some times difficult to reliably adapt a linear scan ner to the skin in longitudinal planes, a sector scanner may be useful in specific cases 16 . The sonographically easily discernible facial artery and facial vein run across the gland. The submandibular gland extends cranially up to the mandible and the mylohyoid muscle and has a close relationship to the anterior belly of the digastric muscle. The submandibular gland sur rounds the posterior border of the mylohyoid muscle in an arc and often reaches ventromedi ally as far as the sublingual gland. An echopaque structure with posterior shadowing is often pro jected into the hilar region of the submandibu lar gland. Here, one must differentiate between parts of the hyoid and sialoliths of the subman dibular gland, both of which can show compa rable image characteristics. If parts of the hyoid are in question, displacements can be observed 37 • Chapter 3. Diagnostic And Imaging Methods • during swallowing motions. The sonographic image characteristics of the submandibular gland comprise an intermediately echogenic fea ture with a regular reflection pattern, corre sponding in appearance to the parenchymal echo Fig. 38. Sonoanatomy of the right submandibular gland, oblique axial view. GSM = submandibular gland ZU = Tongue pattern of the parotid gland (Fig. 38). The course of the efferent glandular duct can occa sionally be visualized with the aid of highres olution ultrasound scanners, even if there is no obstruction of the duct. THE SUBLINGUAL GLAND The examination of the sublingual gland in volves no essential differences in procedure compared to the examination of the subman dibular gland. The scanner is placed on the skin in a transverse plane in the median line imme diately below the mandible, thus allowing vi sualization of both sublingual glands. Visualization of the sublingual gland can at times be difficult to achieve. The sublingual gland is located under the mucosa in the floor of the mouth, below the tip of the tongue, close to the lingual frenulum. Posteroirly the dorsal glands frequently touch the submandibular gland. The gland is bounded ventrally and medially by the geniohyoid and genioglossus muscles and cau dolaterally by the mandible (Fig. 39). The short efferent duct normally cannot be imaged. PATHOLOGIC FINDINGS Acute Sialadenitis Within the scope of acute sialadenitis, a dif fuse enlargement of the entire afflicted gland can be observed. The organ can be reliably de marcated from adjacent structures. The paren chymal pattern appears loosely connected, in homogeneously, roughly textured and more hypoechogenic. As we have to deal with paired organs it is valuable to compare both glands in one picture (Fig. 310). These findings are at tributed to the edematose inflammation swell ing of the organ and to the increased fluid con tent of the parenchyma transformed by the inflammation process. Occasionally, circumscript hypoechogenic masses can be detected that are indicative of a concomitant intraglandular lymph nodes in the parotid gland. Liquefication zones — as signs of abscess formation, appear hypoechogenic to echo 38 • Modern Management Preserving the Salivary Glands • Fig. 39. Frontal view of the floor of the mouth. Upper right: corresponding anatomical illustration UK = mandible MGH = geniohyoid muscle MGG = genioglossal muscle MM = mylohyoid muscle GSL = sublingual gland Z = tongue MD = anterior venter of digastric muscle Fig. 310. Acute sialadenitis of the left submandibular gland,oblique axial plane. Hypoechogenic enlargment. Right side shows normal contralateral gland GSM = submandibular gland Z = tongue 39 • Chapter 3. Diagnostic And Imaging Methods • free with hyperechogenic border wall and distinct distal signal enhancement (Fig. 311). Roughly patterned hyperechogenic echoes at the centre of such liquefaction foci can correspondent to ne crotic tissue contributions (Fig. 312). Fig. 311. Acute sialadenitis of the left parotid gland, intraglandular abscess, axial plane UK = mandible MM = masseter muscle GP = parotid gland Fig. 312. Acute Sialdenitis of the right submandibular gland with intraglandular abcess formation GSM = submandibular gland ZU = tongue 40 • Modern Management Preserving the Salivary Glands • Chronic Sialadenitis The sonographic image is highly dependent on the duration and the degree of inflammation of the glandular parenchyma. On the whole, a distinctive increase in the roughness of the echo texture is observed; the internal structure appears inhomogeneous, probably as a consequence of scarred parenchyma fibrosis (Fig. 313). In ad dition, small cystic echo free domains are formed that correspond to circumscript duct ectasias (Fig. 314). 21, 22 Occasionally, intrag landular concrements become visible as echo paque structures with distal shadowing. As in the case of acute sialadenitis, a conclusive dis tinction between the various pathogenic forms Fig. 313. Chronic sialadenitis axial plane of right parotid gland GP = parotid gland UK = mandible Fig. 314. Chronic sialadenitis axial plane of right parotid gland GP = parotid gland UK = mandible MM = masseter muscle 41 • Chapter 3. Diagnostic And Imaging Methods • of chronic sialadenitis cannot be made using sonography. Patients suffering from Sjogren’s disease show sonographically enlarged, inhomo geneously structured, hypoechogenic salivary glands. Numerous hypoechogenic circumscript masses are detected intraparenchymatously that may correspond to cystic duct extensions on the one hand or enlarged intraglandular lymph nodes on the other hand. Sonographical ly the structure of the salivary glands appears “cloudy” (Figs. 315 and 316). 23 Epitheloid cell sialadenitis (Heerfordt’s disease) is sono Fig. 315. Chronich sialadenitis in Sjogren’s disease with enlarged echoinhomogenous parenchymal texture, axial plane of right parotid gland GP = parotid gland UK = mandible MM = masseter muscle MAST = mastoid bone CO = oral cavity Fig. 316. Chronic Sialadenitis of both submandiblar glands in Sjogren’s disease , oblique axial plane GSM = submandibular gland MM = mylohyoid muscle Z = tongue 42 • Modern Management Preserving the Salivary Glands • graphically characterized by an echo rich struc ture interrupted by numerous enlarged lymph nodes, which appear as hypoechogenic tu mours 24 (Fig. 317). Küttner's tumour of the submandibular gland occurs like an echopoor formation within parts of the submandibular gland and can easily be mistaken as an adenoma (Fig. 318). 25 Ultra Fig. 317. Chronic Epitheloid cell sialadenitis (Heerfordt’s dis ease) of the right parotid gland, axial plane. Lower right: CT (same patient) scan with bilateral parot id gland enlargement GP = submandibular gland MM = masseter muscle UK = mandible Fig. 318. Küttner’s tumor of the submandibular left oblique axial plane. GSM = submandibular gland 43 • Chapter 3. Diagnostic And Imaging Methods • sound can detect alterations after radiotherapy. The echohomogenous pattern disappears after ra diation and a more hypoechogenic and sometimes irregular pattern appears as a sign of loss of func tion (Fig. 319). Other secondary pathological changes (edema, infections, and soft tissue tu mours) around the salivary glands can be distin guished very easily from a primary salivary gland pathology (Fig. 320 and 321). Fig. 319. Atrophic left parotid gland after radiotherapy, axial plane GP = submandibular gland MM = masseter muscle UK = mandible Fig. 320. Edema of the left parotid gland after neck dissection, axial plane GP = parotid gland MM = masseter muscle 44 • Modern Management Preserving the Salivary Glands • LYMPHNODE ENLARGEMENTS Lymphnodes can be found within the parot id gland but only around the submandibular gland due to the embryological development. In the ultrasound image of a sonographically unre markable glandular parenchyma, mostly multi ple hypoechogenic masses that are essentially free from any distal signal enhancement can be discerned. No reliable evidence can be derived from sonography that would permit a conclusive differential diagnosis between benign and malig nant lymph node enlargements. Furthermore, a reliable distinction between reactive lymphad enitis (Fig. 322), a NonHodgkin’s lymphoma Fig. 321. Atheroma GP = parotid gland Fig. 322. Intraglandular Lymph node of the parotid gland, axial plane GP = parotid gland MM = masseter muscle UK = mandible 45 • Chapter 3. Diagnostic And Imaging Methods • Fig. 323. NonHodgkin’s lymphoma. Manifestation in the left parotid gland, axial plane GP = parotid gland UK = mandible (Fig. 323), a MALTlymphoma (Fig. 324) or intraglandular metastatic spread is not secure ly possible on the basis of sonographic find ings. 26 Clinical signs, number, arrangement and sometimes texture of the nodes may lead to the diagnosis but do not resemble histology. Like in lymph node enlargements of the neck, some authors mention the so called “Hilus” as a sign of reactive lymphadenitis. 27 Fig. 324. MALTLymphoma in left parotid gland, axial and longitudinal planes GP = parotid gland RF = Lymphoma 46 • Modern Management Preserving the Salivary Glands • CYSTIC TUMOURS Congenital or acquired cysts of the salivary glands are normally filled with a transparent liquid. Because of this, the typical sonographic criteria for cystic structures are identifiable: an echo free tumour, sharply bordered with distal acoustic enhancement (Fig. 325). 18, 28 If cys tic tumours are sonographically detected in both parotid glands, and if the patient’s histo ry corresponds, lymphoepithelial cysts caused by HIV infection should be suspected. 29 Fig. 325. Parotid gland cyst, axial plane GP = parotid gland RF = cyst SIALOLITHIASIS An echopaque reflection with distinct distal shadowing is the most characteristic sono graphic criterion for a salivary gland concre ment (Fig. 326). 30 Whereas the distal shad owing feature is mostly detectable, the reflection may at times be only indistinct, or lacking. This phenomenon is the result of the reflected ultrasound component not reaching the transducer, but being dispersed out of the image plane. Especially stones of the parotid duct may be visualized with more efforts, because the more organic components (Fig. 327). Here sometimes only a distinct echopaque reflex without distal shadowing may be detected. But in many of these cases dilation of the efferent ducts of the salivary glands can be considered as a further indirect indication of a stone disorder if a concrement cannot be reliably identified. 21 Nonetheless, a duct dilation can also be caused by constrictions in the connective tissue (Fig.328), e.g. as ob served after an inadequately performed incision of a duct or after acute inflammation. Concre ments located in the region of the large salivary glands can be reliably detected by sonography from a diameter of 1.5 to 2 mm upwards (Fig.329). 31 In differential therapy, the exact determination of the position of sialoliths (in traglandular, extraglandular, intraductal) has great significance. 47 • Chapter 3. Diagnostic And Imaging Methods • Fig. 326. Left: Sialolithias of the parotid gland, axial plane Right: concrement after surgical extraction. GLP = parotid gland UK = mandible Fig. 327. Depiction of the left parotid duct caused by distal obstructive concrement, proximal sialadenitis, axial plane GP = parotid gland UK = mandible DUCT = parotid duct 48 • Modern Management Preserving the Salivary Glands • Fig. 328. Dilation of stensen‘s duct in right parotid gland, axial plane UK = mandible DS = dilated stensen‘s duct GLP = parotid gland Fig. 329. Intraductal concrements located in the left distal stensen‘s duct, axial plane UK = mandible MM = masseter muscle CO = oral cavity 49 • Chapter 3. Diagnostic And Imaging Methods • For differential diagnoses one may think also about air within the ducts, like in the case of pneumoparotitis, foreign bodies, angiolithi asis, calcified lymphnodes or arteriovenous mal formations (Fig. 330). Fig. 330. Differential diagnosis Upper left: radiograpic image of phlebolithic concrements Upper right and lower left: Bscan, colordoppler imaging of a parotid arteriovenous mal formation (same patient) SIALADENOSIS All large salivary glands can be simultaneous ly affected by sialadenosis. In a sonographic im age, the afflicted salivary glands appear indis tinctly enlarged and can be demarcated from surrounding structures only with difficulty. The echosrudcture appears homogeneously hypere chogenic (Fig. 331). No tumourlike lesions are present in sialadenosis. 15 BENIGN EPITHELIAL TUMOURS OF THE SALIVARY GLANDS A clearly defined border between the sur rounding salivary gland tissue and the tumour itself is a characteristic feature of a benign sal ivary gland tumour. 32 Pleomorphic adenomas exhibit a homogeneous/hypoechogenic texture. However, inhomogeneous structures with sol id and cystic contributions may occasionally be discernible as well. Distal acoustic enhance 50 • Modern Management Preserving the Salivary Glands • ment is the rule in these cases (Fig. 332). Monomorphic adenomas (adenolymphomas) can also appear sonographically mogeneous and hypoechogenic, as in the case of pleomorphic adenomas. 15, 29 If proportion of cystic structures is high, an adenolymphoma can also present it self completely echo free with extended distal enhancement. Sometimes septa can be identi fied within the tumour (Fig. 333). The re maining, less common types of benign tumours of the salivary glands (e.g. basalcell adenoma, oncocytomas, lymphoepithelial lesions) show Fig. 331. Hyperechogenic enlargement in Sialadenosis, axial plane of the right parotid gland GP = parotid gland MM = masseter muscle Fig. 332. Pleomorphic adenoma of the left parotid gland, axial plane GP = parotid gland MM = masseter muscle UK = mandible 51 • Chapter 3. Diagnostic And Imaging Methods • similarly unspecific sonomorphologic fea tures. 33 A conclusive sonographic identification and differentiation between the diverse types of benign tumours of the salivary glands is therefore not possible at the present time, even though a substantial cystic proportion tends to indicate an adenolymphoma, and a general ab sence of cystic areas points toward a pleomor phic adenoma. As sonography is unable to visu alize nerves, it is not possible to establish reli ably the relationship of parotid tumours to the facial nerve. To a certain degree, though, parot id tumours can be assigned to the “superficial” or “deep” portion of the gland (Fig. 334). Fig. 333. Warthin‘s tumor of the left parotid gland, axial and longitudinal planes GP = parotid gland Fig. 334. Adenoma of the right “deep” part of the parotid gland next to the mandibular ramus, axial plane GP = parotid gland MM = masseter muscle UK = mandible 52 • Modern Management Preserving the Salivary Glands • BENIGN NONEPITHELIAL TUMOURS OF THE SALIVARY GLANDS Lymphangiomas and hemangiomas (Fig. 330) show similar sonomorphologic characteristics, making their clear differentiation impossible. At examination, loosely connected, alveolar, structural patterns composed partially of hypo echogenic and hyperechogenic areas can be detected (Fig. 335). Sonography allows to as sess the depth of penetration and the extension of this mass into the respective salivary gland and into the periglandular soft tissue regions. Intra and extraglandular lipomas (Fig. 336) appear as sharply demarcated, ovoid masses Fig. 335. Haemangioma of the parotid gland, axial plane GP = parotid gland MM = masseter muscle UK = mandible Fig. 336. Superficial lipoma of the right parotid gland, axial view GP = parotis gland UK = mandible 53 • Chapter 3. Diagnostic And Imaging Methods • with hypoechogenic, homogeneous reflection patterns. A lipoma shows a more hypoechogen ic reflection pattern than the remaining paren chyma of the salivary gland, but its echo tex ture is more hyperechogenic than that of the other types of intraglandular tumours and ex hibits a linear, hyperechogenic feathery texture. MALIGNANT TUMOURS OF THE SALIVARY GLANDS An unclear margin and an inhomogeneous echo texture are signs of malignant development of salivary malignant tumours (Fig. 334—341). However, these sonographic indications are Fig. 337. Metastasis of a squamous cell carcinoma of the right parotid gland, axial plane GP = parotid gland UK = mandible Fig. 338. Lymphoepithelial carcinoma of the left parotid gland, longitudinal plane GP = parotid gland 54 • Modern Management Preserving the Salivary Glands • Fig. 339. Squamous cell carcinoma of the right parotid gland, axial plane GLP = parotid gland Fig. 340. Mucoepidermoidcarcinoma, axial plane left parotid gland UK = mandible GLP = parotid gland sometimes absent, so that in the preoperative stage, a definite statement as to the benign or malignant character of tumour development cannot be made with ultimate certainty. Sono graphically it is possible to describe the relation between invasive tumour growth and the sur rounding tissue, but it is impossible to detect malignant invasion of the facial nerve. If malig nancy is suspected by ultrasound FNA, it may be helpful to classify the tumour more ade quately in the preoperative staging. If the tu mour margins cannot be precisely imaged by 55 • Chapter 3. Diagnostic And Imaging Methods • sonography — especially when the tumour has reached bone structures — diagnostic imaging of the patient should be expanded to include CT and/or MRI examinations at all costs. SUMMARY Sonography has established itself as the pri mary imaging technique in the diagnosis of sal ivary gland diseases. A sonographic examina tion is generally sufficient to diagnose sialolithiasis. If chronic sialadenitis or sialade nosis is suspected and if sonographic findings turn out to be insufficient, a conventional sia lography or nowadays sialoscopy may be re quired in specific cases. Histologic clarification is imperative once the presence of a mass has been established. In the event that the exten sion and relationship of the tumour to its sur roundings cannot be determined sonographi cally, a subsequent CT or MRI examination should be performed. COLOUR DOPPLER SONOGRAPHY OF SALIVARY GLANDS The regular Bscan is a wellestablished tool in diagnosing diseases of salivary glands. In tu mours located in the salivary glands it is of great interest to noninvasively acquire clini cal information such as growth and invasive ness and to establish an accurate diagnosis prior to surgery. Before the benefits of sophisticated ultrasound workups were available, this was performed on a regular basis by correlating sim ple sonomorphological criteria such as the echofree regions with specific histological en tities. 34 Colourcoded duplex sonography is a com bination between Bscan sonography, a pulsed Doppler system and the colourcoded represen tation of perfused areas. The main principle of colourcoded duplex sonography is a shift of transduceremitted frequency, which is caused by reflection from the floating erythrocytes. Fig. 341. Rhabdomyosarcoma, axial plane right parotid gland UK = mandible GP = parotid gland MM = masseter muscle 56 • Modern Management Preserving the Salivary Glands • The speed and direction at which the erythro cytes approach and move away from the trans ducer, provides the information necessary for the function of the duplex sonography. The di rection of the blood flow is normally coded with blue and red. Qualitatively the assessment of the colour distribution gives information about the vascularization of tumour masses. Quantitatively the measurement of certain pa rameters allows statements concerning blood flow and circulation resistance. Over the last few years colour Doppler sonography has be come a wellestablished part of ENT diagnos tic armamentarium, particularly in the frame work of preoperative assessment of tumours and cervical lymph nodes. 35, 36—38 Since the im plementation of colour Doppler sonography data on colour Doppler characteristics like the blood flow parameters “pulsation index” and “resistance index” have become available for various types of parotid tumour masses. 39 However, no unequivocal differences have been observed between the investigated tumour groups e.g. adenolymphomas, pleomorphic ad enomas and squamous cell carcinomas of the parotid gland. Other studies devoted to quan titative aspects of vascularization 40, 41 mostly found increased vascularization in malignant parotid tumours as compared to benign parot id tumours. The option of using Doppler signalenhancing agents to achieve improved visualization of tu mour vascularization has provided new possibili ties for characterizing masses and pathologies. (Figs. 342, 343) Analysis of microvascular ization and timedependent changes after ad ministration of Doppler signalenhancing agent are promising new tools to determine whether these changes are typical of certain types of parotid gland tumours. 42, 43 (Figs. 342, 343) Fig. 342. Colordoppler image of intraglandular abscess formation, left parotid gland, axial plane 57 • Chapter 3. Diagnostic And Imaging Methods • COMPUTED TOMOGRAPHY AND MAGNETIC RESONANCE IMAGING Salivary glands: In the assessment of tumour lesions of the salivary glands, computed tomog raphy and magnetic resonance tomography are used to determine the localisation as well as the extent of such lesions and also to distinguish between primary tumours of the salivary sys tem and those originating from different tissues or affecting the glands from the outside. If a tumourous lesion of the salivary glands is suspected, magnetic resonance imaging should be chosen as first choice imaging meth od. Following the intravenous administration of GadoliniumDTPA, healthy gland tissue al ways responds with a significant increase in sig nal intensity. The facial nerve, which does not show signal enhancement after i. v. contrast, can usually be visualized as a low signal struc ture within the parotid gland. Similar to this, the excretory ducts of all salivary glands usu ally display low signal and thus can also be well identified. Examinations in at least two imaging planes are obligatory, the transversal images are used to assess the surface of the glands and their re lationship towards surrounding structures, whereas the coronal planes are used to deter mine the extension of a lesion towards the skull base and the topographic relationship towards the cervical vessels. Computed tomography shows less soft tis sue resolution than magnetic resonance imag ing does, and thus is only the second choice in order to distinguish between different soft tis sue changes and characteristics. However, in case of infiltration of tumours into osseous structures as the ascending mandible, the condylus head or the skull base, computed to mography is most suitable to demonstrate the extent and the location of bone destruction. Inflammatory changes of the salivary glands usually will not require CT or MRI imaging. Still, complications as for example abscesses may justify the use of CT or MRI. In acute sialadenitis, MRsialography might be used. Small concrements in the excretory duct or within the gland itself can be defined as signal Fig. 343. Colordoppler image of distal wharton’s duct facilitating differentiation between duct and neighbouring vascular structures, left axial oblique plane

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Название: Glands Описание: Буклет к конференции по хирургии (отоларингология) Тэги: glands