The Diagnostic Value of Technetium 99m Pertechnetate Salivary Gland Scintigraphy in Patients With Certain Salivary Gland Diseases

PATHOLOGY

The Diagnostic Value of Technetium 99m Pertechnetate Salivary Gland Scintigraphy in Patients With Certain Salivary Gland Diseases Chuan-Bin Wu, MS,* Hong Xi, MS,y Qing Zhou, DDS, PhD,z and Liang-Mei Zhang, MSx Purpose:

To evaluate the diagnostic value of technetium 99m pertechnetate salivary gland scintigraphy in patients with certain salivary gland diseases.

Materials and Methods:

We evaluated 47 patients: 25 with chronic obstructive parotitis, 12 with sialolithiasis, and 10 with Sj€ ogren syndrome. All of the patients underwent preoperative 99mTc-pertechnetate salivary gland scintigraphy. Patients with chronic obstructive parotitis also underwent ultrasonography, sialography, and sialoendoscopy; patients with sialolithiasis also underwent ultrasonography and computed tomography; and patients with Sj€ ogren syndrome also underwent ultrasonography and sialography. We made comparisons between 99mTc-pertechnetate salivary gland scintigraphy and the other aforementioned diagnostic tests to investigate the role of 99mTc-pertechnetate salivary gland scintigraphy in diseases of the salivary glands.

In patients with chronic obstructive parotitis, 99mTc-pertechnetate salivary gland scintigraphy showed reduced excretion by the affected glands, whereas uptake was nearly normal. Among patients with sialolithiasis, 99mTc-pertechnetate salivary gland scintigraphy showed reduced excretion by the affected glands and decreased uptake in 5 patients. In patients with Sj€ ogren syndrome, 99mTc-pertechnetate salivary gland scintigraphy showed a decrease in both excretion and uptake by the 4 glands.

Results:

Conclusions: Technetium 99m pertechnetate salivary gland scintigraphy played a substantial role in the diagnosis and differential diagnosis of salivary gland diseases. Ó 2015 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 73:443-450, 2015

Technetium 99m pertechnetate salivary gland scintigraphy plays a substantial role in the diagnosis of diseases that affect the salivary glands through the use of radionuclide-labeled compounds. This easy, noninvasive, and accurate method assesses the functional state of and degree of injury to the gland, resulting in highly valuable clinical information.1 Salivary gland diseases include non-neoplastic salivary gland diseases and neoplastic salivary gland

diseases.2 The former include sialadenitis, sialolithiasis, Sj€ ogren syndrome, and other similar disorders, whereas the latter comprise benign and malignant tumors. Different physical and chemical examinations, including ultrasonography, sialography, computed tomography, and magnetic resonance imaging, are commonly used to diagnose various salivary gland diseases.3 However, 99mTc-pertechnetate salivary gland scintigraphy has rarely been used to evaluate

*Resident, Department of Oral and Maxillofacial Surgery, School

Medical University, Shenyang 110002, Liaoning Province, PR China;

of Stomatology, China Medical University, Shenyang, China.

e-mail: [email protected]

yResident, Department of Pediatric Dentistry, School of

Received May 15 2014

Stomatology, Jilin University, Changchun, China. zProfessor, Department of Oral and Maxillofacial Surgery, School

Ó 2015 American Association of Oral and Maxillofacial Surgeons

of Stomatology, China Medical University, Shenyang, China.

0278-2391/14/01490-6

Accepted September 18 2014

xResident, Department of Oral and Maxillofacial Surgery, School

http://dx.doi.org/10.1016/j.joms.2014.09.013

of Stomatology, China Medical University, Shenyang, China. Address correspondence and reprint requests to Dr Zhou: Department of Oral and Maxillofacial Surgery, School of Stomatology, China

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SALIVARY GLAND SCINTIGRAPHY

FIGURE 1. Technetium 99m pertechnetate salivary gland scintigraphy. The radioactivity in the left parotid gland diminished slightly 20 minutes after stimulation with vitamin C, showing poor excretion and ductal system obstruction. Wu et al. Salivary Gland Scintigraphy. J Oral Maxillofac Surg 2015.

salivary gland function4-6; the role of this method in the diagnosis of diseases of the salivary gland has been neglected. We included 47 patients with salivary gland diseases in our study, and all of the patients underwent 99mTc-pertechnetate salivary gland scintigraphy, as well as routine preoperative examinations, to determine the diagnostic value of 99m Tc-pertechnetate salivary gland scintigraphy.

Materials and Methods Institutional review board approval was obtained from the our institution, and all participants signed an informed consent agreement. We selected 47 patients with salivary diseases for our study from December 2010 to December 2013 at the Department of Oral and Maxillofacial Surgery, School of Stomatology, China Medical University, Shenyang, China. Among the patients, 25 had parotitis, 12 had sialolithiasis, and 10 had Sj€ ogren syndrome. The patients ranged in age from 21 to 70 years, with a mean age of 51 years. The disease duration

ranged from 3 months to 3 years, with a mean length of 19 months. All of the patients underwent preoperative 99mTc-pertechnetate salivary gland scintigraphy. Patients with chronic obstructive parotitis (COP) underwent ultrasonography, sialography, and sialoendoscopy; patients with sialolithiasis underwent ultrasonography and computed tomography; and patients with Sj€ ogren syndrome underwent ultrasonography and sialography. Patients with COP received ductal dilation and irrigation with the aid of sialendoscopy under local anesthesia. Stones were removed under local anesthesia in 7 patients with sialolithiasis, and the stone and gland were excised under general anesthesia in the remaining 5 patients. The 10 patients with Sj€ ogren syndrome were referred to the rheumatology clinic. SALIVARY GLAND SCINTIGRAPHY

The patient was positioned supine with the chin raised. After intravenous injection of approximately

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FIGURE 2. Sialography. Expansion into the ducts occurred, indicating a diagnosis of chronic obstructive parotitis (same patient presented in Fig 1). Wu et al. Salivary Gland Scintigraphy. J Oral Maxillofac Surg 2015.

370 MBq (10 mCi) of 99mTc-pertechnetate, salivary gland scintigraphy was performed for 30 minutes with single photon emission computed tomography (e-cam 9550; Siemens Medical Solutions, Malvern, PA), using a low-energy, high-sensitivity, parallelhole collimator at 1 minute per frame. Vitamin C, 0.2 g, was administered orally at 20 minutes to stimulate salivary gland excretion. The patient’s head was fixed during scintigraphy. Images were recorded in a 64  64 matrix. The energy window around the 140-keV photopeak of 99mTc was 20%. Regions of interest (ROIs) of each parotid and submandibular gland were drawn manually, with background ROIs painted over the brain. Data were digitally stored and plotted on separate time-activity curves for each salivary gland after manual selection of the glands. The uptake ratio at 15 minutes (UR15) was defined as [(Salivary gland count at 15 minutes – Background count)/Net counts of tracer]  1000&. The excretion fraction (EF) was defined as (1 – Minimum salivary count after stimulation/Maximum salivary count before stimulation)  100%.

FIGURE 3. Sialendoscopy. A mucous plug was found in the ductal lumen (same patient presented in Fig 1). Wu et al. Salivary Gland Scintigraphy. J Oral Maxillofac Surg 2015.

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SALIVARY GLAND SCINTIGRAPHY

FIGURE 4. Technetium 99m pertechnetate salivary gland scintigraphy. The left submandibular gland displayed a low level of radioactivity before and after stimulation, showing poor uptake and excretion, resulting in loss of salivary function. Thus it was determined that the gland should be removed based on quantitative indicators. Wu et al. Salivary Gland Scintigraphy. J Oral Maxillofac Surg 2015.

Results CHRONIC OBSTRUCTIVE PAROTITIS

In patients with COP, 99mTc-pertechnetate salivary gland scintigraphy showed reduced excretion by the affected glands and uptake was approxi-

mately normal (Fig 1). Sialography indicated expansion or stenosis in the ductal system (Fig 2), and sialendoscopy showed engorgement of the duct wall with a mucous plug in some cases (Fig 3). The stones were not visible using preoperative ultrasonography.

FIGURE 5. Technetium 99m pertechnetate salivary gland scintigraphy. The right parotid gland was unresponsive to vitamin C stimulation. In addition, the radioactivity continued to increase, showing a large decrease in secretion. Wu et al. Salivary Gland Scintigraphy. J Oral Maxillofac Surg 2015.

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FIGURE 6. Computed tomography. The stone was evident on the left side of the submandibular gland (same patient presented in Fig 4). Wu et al. Salivary Gland Scintigraphy. J Oral Maxillofac Surg 2015.

SIALOLITHIASIS

Uptake and excretion by the glands were substantially decreased in 5 patients with sialolithiasis (Fig 4), and the patients agreed to undergo removal of both the stones and the glands. In the remaining 7 patients, 99mTc-pertechnetate salivary gland scintigraphy showed normal or slightly reduced uptake and substantially reduced excretion (Fig 5); the stones were removed with the aid of sialendoscopy. Ultrasonography and radiographic imaging showed stones of various sizes in the affected glands (Fig 6). € SJOGREN SYNDROME

Among patients with Sj€ ogren syndrome, 99mTcpertechnetate salivary gland scintigraphy showed both decreased uptake and excretion by the 4 glands (Fig 7). Sialography showed punctate to round sialectasia (Fig 8).

Discussion Common non-neoplastic salivary gland diseases include sialadenitis, sialolithiasis, and Sj€ ogren syndrome. Specific examinations are used to diagnose the various diseases. Technetium 99m pertechnetate salivary gland scintigraphy is a noninvasive treatment. Through active transport, ductal cells can

concentrate massive amounts of 99mTcO4 and secrete it into the lumen; it is subsequently exported into the mouth with saliva.7 With this technique, quantitative indicators to assess salivary gland function and morphologic data can be obtained. Technetium 99m pertechnetate salivary gland scintigraphy can be used to determine the location, morphology, and size of the gland. In addition, the amount of accumulated 99mTcO4 reflects both uptake by the gland and excretion by the duct.8 During scintigraphy, both parotid glands and both submandibular glands were evaluated. All 4 glands were examined concomitantly in each patient. After scintigraphy, the uptake ratio at 15 minutes (UR15), excretion fraction (EF), and time-activity curves were evaluated. The radioactivity in the ROI typically increases before vitamin C stimulation and decreases after stimulation. Among the 25 patients with COP, 34 parotid glands were affected. Among the 12 patients with sialolithiasis, 12 submandibular glands were affected. Among the 10 patients with Sj€ ogren syndrome, 20 parotid glands and 20 submandibular glands were affected. By use of 99mTc-pertechnetate salivary gland scintigraphy, salivary gland uptake, excretion, and acid reactive functionality were clearly and accurately characterized to provide valuable information for clinical diagnosis. This method is safe in terms of chemistry,

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SALIVARY GLAND SCINTIGRAPHY

FIGURE 7. Technetium 99m pertechnetate salivary gland scintigraphy. The uptake ratio at 15 minutes (UR15) and excretion fraction (EF) showed abnormal uptake and excretion, respectively, by the 4 salivary glands. These results were indicative of an autoimmune disease (ie, Sj€ ogren syndrome). Wu et al. Salivary Gland Scintigraphy. J Oral Maxillofac Surg 2015.

biology, and radiation dosimetry, and it avoids potential damage resulting from radionuclide injection through venipuncture.9 Thus far, sialadenitis has shown great marks for both diagnosis and treatment; with sialendoscopy, it is possible to visually diagnose and treat sialadenitis.10,11 In our group all 25 patients underwent preoperative 99mTc-pertechnetate salivary gland scintigraphy that showed normal uptake and decreased excretion. Accordingly, we were able to diagnose COP. Sialography showed different extents of expansion and stenosis within the ductal system, thereby supporting the diagnosis of COP. However, sialography is not suitable for all patients: It is an inconvenient technique for patients with suppurative sialadenitis; it cannot be used in patients who are allergic to iodine; and it is painful for some patients, which could potentially interrupt the procedure. In these situations 99mTc-pertechnetate salivary gland scintigraphy can be used as an alternative to classic radiographic sialography for the diagnosis of COP.

Among the salivary gland stones, the submandibular glands are the most common location for salivary stone formation, accounting for roughly 80 to 92%, and the incidence of parotid gland stones ranges from 6 to 19%.12 Routine treatments are used for calculi.13-15 Calculi with a diameter less than 7 mm were excised under sialendoscopy, whereas laser lithotripsy was used to remove blocks individually for larger calculi. In some cases both the gland and the stone were removed simultaneously to simplify the procedure. It is appropriate to excise the gland when it is not functional, but excising glands with normal function should be avoided. Quantitative methods are needed to assess whether the gland is worth saving. Technetium 99m pertechnetate salivary gland scintigraphy plays a substantial role in evaluating gland function. In our series uptake and excretion were poor because of long-term stimulation induced by inflammation in 5 patients. For these patients, it was appropriate to remove both the gland and stone. For the other 7 patients, only the stone was removed.

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FIGURE 8. Sialography. Punctate to round sialectasia was found on both sides of the parotid glands (same patient presented in Fig 7). Wu et al. Salivary Gland Scintigraphy. J Oral Maxillofac Surg 2015.

Patients with Sj€ ogren syndrome complain of swelling and discomfort due to the affected glands, making it difficult to distinguish this condition from sialadenitis. Routine examinations such as sialography and labial gland biopsy can be used to diagnose the condition, but these techniques can be painful and have not been widely accepted.16,17 However, 99mTcpertechnetate salivary gland scintigraphy can be used to distinguish this condition. Sialadenitis affects the glands in either a unilateral or a bilateral manner and is rarely observed in all 4 glands. Thus Sj€ ogren syndrome is likely when all 4 glands are affected. Sialography showed punctate to round sialectasia. Technetium 99m pertechnetate salivary gland scintigraphy is a sensitive method for the diagnosis of patients with Sj€ ogren syndrome, which is consistent with the observations of Markusse et al,18 who argued that a diagnosis of abnormal excretion is dependent on sufficient concentrations and that abnormal uptake occurs before excretion. Sialography cannot distinguish between issues related to uptake and excretion, further showing the advantages of 99mTc-pertechnetate salivary gland scintigraphy. In addition, 99mTcpertechnetate salivary gland scintigraphy can be used to assess gland morphology and function, providing

valuable information for clinical diagnosis. Compared with sialography, 99mTc-pertechnetate salivary gland scintigraphy is noninvasive, safe, and easy; in addition, it causes little pain and is convenient for patients. In conclusion, 99mTc-pertechnetate salivary gland scintigraphy represents an effective method to distinguish salivary gland diseases. It does not interfere with other techniques and is easily performed.

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