Major salivary gland masses: comparison of MR imaging and CT

Computed tomography (CT) and magnetic resonance (MR) imaging studies were done prospectively in 21 unselected patients in whom 28 major salivary glands had pathologic changes. Blinded and final readings were used to establish the relationship of the lesion to the plane of the facial nerve (parotid masses), whether the lesion was intrinsic to the gland, and whether the lesion was aggressive. In the blinded reading, CT was superior to MR imaging in eight instances; in the final reading, however, with clinical information available, CT was superior in four cases of inflammatory salivary gland "masses." CT and MR imaging provided the same diagnostic information in all cases of salivary gland neoplasms. T1- and T2-weighted images proved of equal value in detection of salivary gland lesions, and use of both provided no additional specificity. In most cases, T1-weighted images alone provided the information necessary for surgical management. MR imaging is a reasonable first choice if a neoplasm is likely; the potential for improved tissue contrast at the margins of a tumor may be particularly useful. If a mass may be of inflammatory origin, contrast material-enhanced CT is a more reasonable first choice.

CT sialography and conventional sialography in the investigation of parotid masses

In a 3-year period computed tomography (CT), both plain and in combination with sialography, and conventional sialography were used in 59 patients who had or were suspected of having salivary gland tumors, with special regard to attenuation in different tumors and the tumor borders. The diagnostic information obtained with CT sialography and conventional sialography was evaluated. The most valuable advantage of parotid CT sialography is the possibility of demonstrating the tumor and its actual size and relationship to the surrounding structures. The differentiation between benign and malignant tumors must be based mainly on clinical investigation and fine-needle biopsy. Conventional sialography may be an important complement to CT sialography because of its ability to illustrate the morphology of the finest ducts.

[Digital subtraction dacryocystography and sialography]

Fourteen examinations of the tear ducts and 21 sialograms were performed using digital subtraction and conventional techniques. In nine of the former and 15 of the latter, digital subtraction produced better results, in the remainder conventional technique was equally good. The advantages of digital subtraction are due to the removal of superimposed structures of the skull. Dose measurements at the level of the lens of the eye showed a greatly reduced radiation dose when using digital subtraction, as compared with conventional dacryocystography. Digital subtraction techniques with pulsed radiation and the ability to perform pixel shift is an optimal method for performing radiological examinations of the tear ducts and salivary glands.

[Present status and place of sialography]

Roentgenography without contrast media and sialography, as well as the basic facts concerning the radiodiagnostic of the salivary gland, are all discussed with regard to the most current equipment, examination techniques, the positioning of patients, and the problems involved in contrast media. The technique used in more than 4,000 sialograms is recommended. The diagnostic value of this method is illustrated by means of representative patient series: sialolithiasis, inflammatory disorders, and tumors. The limitations of the method are demonstrated and complementary examinations shown.

Experimental sialography: the effects of retrograde infusion of radiographic contrast media on salivary gland morphology and function. A review article

An experimental model for sialography, involving retrograde infusion of contrast medium into the rat submandibular gland under continuous pressure monitoring, was developed. Morphologic alterations induced during infusion of water- and lipid-soluble radiographic contrast media and the distribution of the media were examined with light and electron microscopy. An uneven distribution of the media throughout the tissue and variations in the degree of the alterations in different parts of the gland were seen at all stages of filling. The changes primarily consisted of dilation of the luminal system, which successively became more pronounced as infusion continued. Infusion of the lipid-based medium consistently resulted in more severe alterations, including changes in the acini. Tracer studies showed that the water-soluble medium leaked out through the intercellular spaces and to the surrounding tissue, whereas the lipid-based medium appeared to be confined to the luminal space. Ductal filling with either medium resulted in a relatively fast recovery; after prolonged infusion, recovery was slower and additional alterations occurred. The acini showed confluence of secretory granules and vacuole formation. After infusion of the lipid-based compound, autophagic vacuoles and granulomatous alterations developed. Prolonged infusion with either medium resulted in atrophy of the parenchyma and connective tissue proliferation in some glands. An inflammatory infiltrate was present in all glands during the recovery period. Functional alterations, primarily consisting of a decrease in flow rate, were noted after prolonged infusion. The increase in intraluminal pressure induced during infusion was most likely the primary cause of the alterations. In addition, the presence of contrast medium contributed to the long-term effects of the procedure.

CT sialography: utilising acinar filling

The technique of computed tomographic sialography (CTS) has been demonstrated to be valuable in the diagnosis of masses of the major salivary glands. Forty-one CT sialograms were performed in 35 patients using acinar glandular filling with oily contrast material. Twenty-two mass lesions and seven cases of inflammatory disease were identified. There were two instances of mild parotitis following the procedure. CTS performed with this technique was found to be a safe, accurate method for evaluating salivary gland masses.

[Comparative study of Hexabrix and Lipiodol UF in sialography]

Many new lipid- and water-soluble contrast media can be used in sialography, the three main criteria of choice being the cost, the quality of filling, particularly of the parenchyma, and its evacuation and clinical tolerance. Duroliopaque possesses very similar physicochemical properties to those of Lipiodol UF, but a sufficiently satisfactory filling of the parenchyma is not obtained. Comparison of Lipiodol UF and Hexabrix in parotid and submaxillary contrast imaging showed good clinical tolerance for both products, but improved parenchymatous filling with Lipiodol UF. However, the more effective glandular evacuation with Hexabrix makes this the product most suitable at the present time for morphologic exploration of salivary glands.

Digital subtraction ductography

Digital subtraction techniques used in the examination of eight patients with salivary and nasolacrimal disease are described. Pleomorphic adenoma, ductal stricture, extrinsic masses, parotid-otic fistula, and a radiolucent calculus were demonstrated. The procedures are more easily performed than film techniques, and pathology is better demonstrated by digital ductography than on a film examination. Image subtraction, reregistration, and window manipulation allowed clear demonstration of ducts about the head and neck, overcoming limitations imposed by inherently high object contrast. Digital subtraction ductography is an important nonvascular application of digital imaging technology.

Sialography and CT-sialography in the diagnosis of parotid masses

Parotid masses were evaluated by sialography and CT-sialography in 22 patients. Nineteen were benign tumors and one a metastasis. All were identified by CT. Two patients with sialoadenitis were misinterpreted at CT. All benign tumors appeared as lobulated, sharply marginated masses, embedded in displaced glandular parenchyma. The metastasis was lobulated, irregular and located within the gland. With sialography, 17 tumors were identified and 3 small superficial tumors overlooked. Both patients with sialoadenitis were diagnosed by sialography. CT-sialography is recommended in patients with suggested parotid masses, and sialography in suggested inflammatory disease.

[Instrument for probe fixation in parotid gland sialography]

An instrument is described for fixing the cannula used for sialography of the submandibular gland. Dislocation of the probe and early discharge of contrast medium can be avoided.

[Current status of serial sialography and sialoscintigraphy in the diagnosis of salivary gland diseases]

Sialographic investigation of enlarged salivary glands contribute to the important decision whether a secretion blockage is caused by a stone, chronic inflammation, sialoadenosis, or a tumour. The results of sialographic investigations have been much improved by the method described by Brands and Schnepper (1967) of specific serial sialography using a single-shot and fast-repeating camera, under fluoroscopic control. The success rate of the sialographic diagnosis on 141 patients in the ENT Department of Saarland University Hospital was 80%. The fact that in four cases spaces, occupying lesions were falsely interpreted or undetected leads to the conclusion that where a tumour is suspected negative sialography should be followed by further diagnostic steps. Scintigraphy of the salivary glands with 4 mCi 99mTechnetium Pertechnetate produces extra information which clearly increases diagnostic accuracy. However, experience to date shows that it is not an alternative to serial sialography but rather a supporting diagnostic method.

Choice of contrast medium in sialography

Contrast media used for sialography were originally developed for other medical applications. Therefore, it was considered desirable to investigate the properties of these substances for use in sialography. Eleven radiopaque substances were selected, and their properties for sialography were studied. An in vitro study was made to determine their contrast qualities and their rate of evacuation after the sialographic examination. In animal experiments the possible harmful effects of the media on salivary gland tissues were studied. Moreover, the effects of the radiopaque material on the extraglandular tissues--which are important in understanding the consequences of spilling into these tissues--were investigated. The results of this study were compared with data from the literature. Conray 80, Amipaque 440, Lipiodol UF, Myodil, and Duroliopaque appear to be the media most suited for sialography, provided glandular overfilling is avoided. A prolonged clinical study is advised for a further selection from these agents.

[Current role of sialography]

Computed tomography, ultrasonography and nuclear medicine are morphological techniques widely accepted in clinical practice. They are used together with plain film and sialography in the study of salivary glands pathology. In comparison with these techniques, the efficacy of sialography in different diseases is discussed and the diagnostic value of CT-sialography related to sialography alone is analyzed.

Digital subtraction sialography

Digital subtraction sialography seems to provide a better display of glandular anatomy and pathological changes of parotid and submandibular gland. Further comparative studies are however necessary to better evaluate this simple and fast procedure.

[A combined method of sialography and CT scan of the parotid gland]

Computed tomography (CT) of parotid gland was performed on 40 patients, immediately following sialography. The results of the combined CT-sialography were compared with those of sialography alone and are presented here. We have come to the conclusion that the main indication for this method, in the study of the parotid gland, is the mass-pathology, particularly situated in deep-lobe and in the pharyngo-maxillary space.

Panoramic sialography: an alternative technique

Pantomographic sialography, referred to in this paper as panoramic sialography, was performed on 30 out of 51 patients. In 21 patients, it proved to be a good alternative technique to conventional sialography whilst in the other nine patients it was the principal method used to study the salivary glands. The techniques employed in this study for both conventional and panoramic methods are described. The radiation dose delivered to the patients was similar for both techniques. Water soluble contrast medium, Conray (325), was used in all cases.

Parotid CT sialography

Computed tomographic (CT) scanning of the parotid gland during the injection of water-soluble contrast medium allows precise mapping of the gland's parenchyma and of any filling defects or extrinsic masses. Thirty-six patients were examined in this way. The most valuable information that was gained was the differentiation of extrinsic and intrinsic tumors and an accurate appraisal of the location of the facial nerve with respect to intrinsic parotid lesions. In the majority of patients the diagnosis of benign or malignant tumor is suggested by the patterns of tumor growth. Inflammatory disease shows diminution in the amount of parotid parenchyma in relationship to interstitial tissues, but the appearance is not sufficiently characteristic for definitive diagnosis.