British Journal of Oral Surgery (1983) 21,268-276 @ 1983 The British Association of Oral and Maxillofacial Surgeons
SIMULTANEOUS COMPUTED TOMOGRAPHY AND SIALOGRAPHY OF THE PAROTID AND SUBMANDIBULAR GLANDS D. WIESENFELD, M.D.Sc., F.D.S.R.C.P.S.,‘* M. M. &RGUSON, B.Sc., M.B.Ch.B., F.D.S.R.C.P.S.’ and N. C. MCIVIILLAN, M.B. Ch.B., D.M.R.D.'
B.D.S.,
‘Department of Oral Medicine and Pathology, Glasgow Dental Hospital and School, 378 Sauchiehall Street, Glasgow, G2 3JZ. ‘Department of Radiology, The Royal Infirmary, Glasgow, G4 OSF. Summary. A technique of simultaneous computed tomography and sialography of the parotid and submandibular glands is described and the examination of 14patients reported. Tumours were diagnosed in six cases and in the remaining eight cases inflammatory lesions were found. Sialographic enhancement offered definite advantages in localisation of lesions and examination of the tumour-normal tissue interface compared with either CT. or sialography alone.
Introduction Tumours and inflammatory lesions of the partoid and submandibular glands may present as facial swelling or asymmetry. In approaching the problem of the diagnosis of these masses, there are three major questions to be answered. Firstly, whether the mass is intra- or extra-glandular. Secondly, whether it is benign or malignant, and thirdly, in the case of parotid gland lesions, whether it lies deep or superficial to the facial nerve. A number of diagnostic techniques have been described for the investigation of salivary gland masses, including sialography, computed tomography (C.T.), combined computed tomography/sialography, scintiscanning and ultrasonography. In the past, the radiological visualisation of tumours associated with the parotid and submandibular glands has been limited to sialography (Meine & Woloshin, 1970). Sialography can aid in the identification of intrinsic masses, which appear as space occupying lesions, but it does not identify extraglandular lesions, nor reliably distinguish between benign and malignant tumours, or accurately localise lesions within the parotid gland. Tomographic assessment of sialograms may increase the accuracy of localisation of parotid gland lesions, in comparison with conventional sialography (Kushner & Weber, 1978). Computerised tomography, (Houndsfield, 1973), is a relatively new diagnostic technique which allows parts of the body to be viewed from multiple planes. Each tomogram represents a cross section through the body, and there is no superimposition. Details of soft tissue are demonstrated, and it is possible to differentiate between specific tissue densities such as fat, blood, tumour or calcified tissue. The parotid and submandibular glands can be demonstrated in this manner, and the technique has been used to identify the absence of the parotid glands in a case of parotid gland aplasia (Wiesenfeldet al., 1983). Parotid and paraparotid tumours may also be identified, due to the differential soft tissue attenuation of tumour and normal (Received
*Present Address: Department CM16 6TN.
4 May 1982; accepted
24 August 1982)
of Oral & Maxillofacial Surgery, St. Margarets Hospital, Epping, Essex
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tissue, (Golding, 1982). The site of origin of these tumours, however, is difficult to identify, as is the nature of the margin with normal salivary gland tissue. A technique has been described where C.T. was carried out following sialography of the parotid gland, (Carter et al., 1978). The radio-opaque medium was retained within the parotid gland during computed tomography, clearly demonstrating the outline of the gland and a ‘mixed tumour’ deep within the gland. In a more extensive review of the technique (Carteretal., 1981) C.T./sialography was also carried out on the submandibular gland. Tumours were better evaluated by this technique than by C.T. or sialography alone. The technique of C.T. immediately following parotid gland sialography has been further reported, (Som & Biller, 1980). In this study 18 patients were examined. Ethiodol (iodised oil fluid injection) was used as a contrast medium, and injected under fluoroscopic control until there was adequate filling. The patients were then transferred to the C.T. Scanner. They were able to diagnose the location of the mass as parotid (nine patients), parapharyngeal (five patients) or involving both the parotid gland and surrounding soft tissues (four patients). The relationship of the lesions to the course of the facial nerve was not described. It was suggested that if the lesions were of parotid origin, a transparotid surgical approach should be used, but that if the lesions were parapharyngeal in origin then a transsubmandibular surgical approach could be used. In 7 patients the tumours were diagnosed as malignant and in 11 patients as benign. A further seriesof 36patients has beenassessed, (Stoneetal, 1981). In thesecases parotid sialography using aqueous contrast media (60 per cent.-76 per cent. meglumine diatrizoate) was carried out at the same time as C.T. scanning. Nine patients were examined for inflammatory disease, 4 for disease extrinsic to the parotid gland and 23 for suspected parotid tumours. In the inflammatory lesions, there was patchy irregular filling. Of the remaining 27 patients, 10 had enlarged lymph nodes only, with no evidence of salivary gland disease. Thirteen patients had intraparotid tumours, 9 of these were benign and 4 malignant. Only 6 of the 9 benign tumours showed a sharply circumscribed, round contrast defect within the gland. Of the malignant lesions, 2 of the 4 cases showed contrast defects with irregular and indistinct margins, and a loss of associated fascial planes, an appearance thought to be suggestive of malignancy. CT. accurately predicted the relationship of the facial nerve to the tumours in all 13 patients, and in the 4 patients with lesions extrinsic to the parotid gland, the relationship of the tumour to the parotid was well demonstrated. In these previous studies, the technique of C.T./sialography has been able accurately to identify whether a tumour was present, and whether the lesions were intraor extraglandular in origin. The identification of the lesions as benign or malignant is less clear, with some tumours not having the supposedly typical characteristics. The relationship of the lesions to the facial nerve is reported as being predictable on the basis of C.T./sialography. However, the landmarks used for predicting the course of the facial nerve may be variable or distorted due to the tumour. Patients and Method
Fourteen patients are included in this study, all of the patients were referred for further investigation of parotid and submandibular lesions. Five patients had submandibular lesions, and nine patients parotid lesions. Continuous infusion pressure monitored sialography (Fergusonet al., 1977) using a water soluble medium, Conray 420 (sodium iothalamate injection B.P. 70 percent W/V) was initially carried out on
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12 patients. The patients then had the sialography repeated with an oily medium, Lipiodol Ultra Fluid (iodised oil fluid injection) or Conray 420, after they had been placed on the scanner. The cannulae were maintained in place during C.T. scanning
Fig. 1 Figure l-Post-irradiation fibrosis of the parotid gland. (A) C.T./Sialogram after the infusion of 2.0 mls Conray 420, appearance suggestive of inadequate filling. (B) C.T./sialogram after the infusion of 0.4 ml Lipiodol ultrafluid, ductal detail can be visualised. (C) C.T./sialogram after the infusion of 1.5 ml Lipiodol ultra fluid demonstraing gland outline and filling defect. There is no evidence of residual tumour deep to the parotid gland.
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and medium infused continuously. All scans were obtained with an E.M.I. 5005 C.T. scanner in the axial projection, at 0.5 to 1.0 centimetre intervals, beginning at the margin of the external auditory canal in the case of parotid, and at the angle of mouth, in the case of submandibular glands. Scanning was continued until the inferior margin of the gland had been reached. Two of the patients had C.T. scanning, prior to the introduction of contrast medium into the glands, to more fully evaluate the diagnostic benefit of sialographic enhancement. Results Three patients had Conray 420 used as contrast medium during C.T. scanning. This material had inadequate density for visualisation of the gland, despite infusion of 0.2 ml/min for ten minutes, the appearance suggested inadequate filling (Fig. 1A) although from conventional sialographic studies the ductal system was known to be well filled. Lipiodal ultra fluid had adequate density for visualisation. After infusion at 0.2 ml/min for 2 minutes, the ductal detail can be visualised (Fig. 1B). Scanning at this stage gives clear representation of small filling defects, which may be obscured with over-filling. Further scans are then taken once 1 .Oml-l .5 ml of media have been infused. This amount of filling demonstrates the gland outline and the relationship to larger intrinsic lesions and external structures clearly (Fig. 1C). Masses were demonstrated in 6 patients, 5 related to the parotid gland and 1 to the submandibular gland. The submandibular lesions was extraglandular, and of the parotid lesions, 2 were extraglandular and 3 intraglandular. Of the 5 patients examined for lesions in the submandibular region (Table I), 4 patients had no mass demonstrated, suggesting that the palpable mass was an enlarged or sclerotic submandibular gland. Two of these patients subsequently had their glands removed, with histology confirming the C.T. diagnosis. The other two patients remain well and were not operated upon. The submandibular mass in patient five (Fig. 2) was well circumscribed and discrete. It lay lateral to the submandibular gland which was
Fig. 2 Figure 2-Hodgkin’s lymphoma. (A) C.T. scan showing tumour in the submandibular space. (B) C.T./sialogram, clearly demonstrating relationship of tumour to the submandibular gland which is displaced medially.
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Table I Results of submandibular Patients
Clinical Problem
1 2 3 4 5
Right Submandibular Left Submandibular Left Submandibular Left Submandibular Left Submandibular
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Mass Mass Mass Mass Mass
C.T./Sialography
Diagnosis
Enlarged Gland Normal Gland Enlarged Gland Enlarged Gland Extraglandular Mass
Sialadenitis Sialadenitis Sialadenitis Sialadenitis Hodgkin’s Lymphoma
displaced tnedially. Enhancement with sialographic media more clearly demonstrated the relationship of the lesion to the gland. At surgery it was found to be Hodgkin’s lymphoma. Ten patients were examined for parotid lesions (Table II). Three intraglandular tumours were identified, all of these lesions being superficial to the facial nerve, although it was difficult to predict the location of one of these tumours on the basis of the C.T. scan (Fig. 3). Two of the tumours were found to be benign (Fig. 4) when examined histologically, and the third was a low grade adenocarcinoma despite its
Fig. 3 Figure 3-Pleomorphic
adenoma of the parotid gland. The tumour lies superficial to the facial nerve.
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Table II Results of parotid scans Patient 6 7
8 9 10 11 12 13 14
Clinical Problem
C.T./Sialography
Diagnosis
Right Parotid Mass Left Parotid Mass Left Parotid Mass Left Parotid Swelling Pharyngeal Carcinoma-Post Left Parotid Swelling Left Parotid Swelling Left Parotid Swelling Bilateral Parotid Swelling
Filling Defect Filling Defect Filling Defect Medial Mass Filling Defect Medial Mass No Mass No Mass No Mass
Adenolymphoma Adenocarcinoma Pleomorphic Adenoma Pharyngeal Carcinoma Radiation Fibrosis Liposarcoma Sialadentis Inflammatory Exocrinopathy Sialosis
Irradiation
Fig. 4 Figure 4-Adenolymphoma of the parotid gland. (A)-(D) C.T./sialogram, 10 mm scans, demonstrating the changing shape of the tumour vertically through the gland. Figure (A) is superior, Fig. (D) is inferior.
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apparent ‘benign’ appearance on C.T. scan, with smooth regular margins (Fig. 5). The postero-anterior sialogram in this case showed draping and displacement of the ducts by the tumour. Both of the extraglandular lesions arose in the pharynx. One patient had a squamous cell carcinoma of the lateral wall of pharynx which had displaced and
Fig. 5 Figure 5--Adenocarcinoma of the parotid gland. (A) P:A. sialogram with draping and displacement of the ducts by the tumour. (B) C.TJsialogram, showing well circumscribed lesion within the parotid.
Fig. 6 Figure bparapharyngeal
liposarcoma C.T./sialogram, shows dumb-bell shaped lesion displacing the parotid gland, and narrowing the pharynx.
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invaded the parotid gland. The second lesion had arisen over some months; displaced the parotid gland laterally and narrowed the pharynx (Fig. 6). At operation it was found to be a parapharyngeal liposarcoma. In the four remaining parotid scans, no mass was demonstrated; one patient had post irradiation fibrosis of the parotid gland, following treatment for a pharyngeal carcinoma (Fig. 1). He wasexamined for any evidence of tumour recurrence in the parapharyngeal space. The diagnoses in the inflammatory exocrinopathy and sialosis other patients were sialadenitis, respectively. Discussion The previously described technique of Parotid and Submandibular C.T./sialography has been modified by the use of continuous-infusion pressure monitored sialography, simultaneously with computed tomography. Of the 14 patients examined, 6 were found to have intra- and extra-salivary gland masses. In all cases the relationship of the mass to the salivary gland was clearly demonstrated. Two of the tumours were benign, and four malignant. Both of the benign tumours were intraglandular parotid in origin, and had radiological features consistent with their benign nature, well circumscribed with smooth margins. Of the 4 malignant tumours, 2 were parapharyngeal in origin, 1 intra-parotid, and the Hodgkin’s lymphoma arose lateral to the submandibular gland. One of the tumours showed features suggestive of malignancy with irregular margins and outline. The other three, a parapharyngeal liposarcoma, an intraglandular adenocarcinoma of the parotid and the Hodgkin’s lymphoma had radiological features supposedly indicative of benign lesions. The relationship of the facial nerve to the mass was correctly predicted in 4 of the 5 parotid tumours. In one case where the tumour was in the posterior part of the parotid gland, the relationship to the facial nerve was unclear (Fig. 5). At surgery it was found to lie superficial to the nerve. Further studies are currently under way on the anatomy of the facial nerve in relation to computed tomography. In the eight cases where no mass was identified, the investigation was considered useful in ruling out the presence of a neoplasm. The value of this technique in diagnosing inflammatory lesions is not yet fully clear, although it seems that other techniques such as conventional sialography, and scintiscanning have advantages. C.T./sialography should not be considered as a primary investigation for inflammatory lesions, as the appearances of patchy irregular filling caused by fibrosis and inflammation may mimic some of the appearances associated with intraglandular malignancy. In these cases the sialographic appearance of sialectasis together with main duct irregularities will suggest the true nature of the lesion.
The authors are pleased to acknowledge the co-operation of Dr J. G. Duncan, Consultant Radiologist at the Glasgow Royal Infirmary, and the willing assistance of the radiography staff at the Glasgow Royal Infirmary and the Glasgow Dental Hospital. We are indebted to the Consultant Surgeons at Canniesbum Hospital, the Dental Hospital, Monklands District and General Hospital and the Victoria Infirmary for co-operating in this study. References Carter, B. L., Hammerschlag,
S. B. & Wolpert, S. M. (1978). Comouterised scanning in otorhinolarynLaryn&ogy, 24, 21. ’ . Carter, B. L., Karmody, C. S., Blickman, J. R. & Panders, A. K. (1981). Computed tomography and sialography: 2 Pathology. Journal of Computer Assisted Tomography, 5, 46. gology. Advances in O&Rhino
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Ferguson, M. M., Evans, A. & Mason, W. N. (1977). Continuous infusion pressure-monitored sialography. International Journal of Oral Surgery, 6, 84. Golding, S. (1982). Computed tomography in the diagnosis of Parotid gland tumours. British Journal of Radiology, 55, 182.
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G. N. (1973). Computerised
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Kushner, D. C. &-Weber, A. L. (1978). Sialography of salivary gland tumours with fluoroscopy and tomography. American Journal of Roentgenology, 130,941. Meine, F. J. & Woloshin, H. J. (1970). Radiological diagnosis of salivary gland tumours. Radiological Clinics of North America, 8, 475.
Som, P. M. & Biller, H. F. (1980). The Combined C.T-Sialogram. Radiology, 135, 387. Stone, D. N., Mancuso, A. A., Rice, D. & Hanafee, W. N. (1981). Parotid C.T. Sialography. Radiology, 138, 393.
Wiesenfeld, D., Ferguson, M. M., Allan, C. J., McMillan, N. C. & Scully, C. (1983). Bilateral Parotid gland aplasia. British Journal of Oral Surgery, (In Press).