Scintillation camera scanning of the salivary glands.

Abstract

It has been known for many years that -1 iodine, bromine, rhenium, and other elements of Periodic Group VII are selectively concentrated by the thyroid gland, salivary glands, and gastric mucosa as iodide, bromide, and perrhenate (1, 2). It was not surprising that technetium 99m, a member of the Seventh Periodic Group introduced as a brain scanning agent by Harper (3), is also concentrated by these organs as pertechnetate. This last is an excellent scanning agent because the short six-hour half-life and the absence of beta emissions make possible larger administered doses with less radiation to the patient's tissue than commonly used brain scanning agents. In addition, its low-energy gamma (140 keV) simplifies collimator design and increases detector efficiency. This agent has been so successful in brain scanning that only recently has attention been turned to the possibility of its use in those other organs in which it is selectively concentrated. We have recently developed a functional and morphological method of examination of the salivary glands using the Anger camera2 and 99mTc pertechnetate. Our findings in 90 patients form the basis for this report. Method 99mTc as pertechnetate is eluted from the resin column of the 99Mo-99mTc generator,3 using 25 ml of pyrogen-free isotonic saline. Immediately after intravenous injection of 10 mCi99mTc pertechnetate, a frontal view of the salivary glands is obtained, centering over the tip of the nose with the crystal perpendicular to the canthomeatal line or with a 5 to 10° caudal angulation of the crystal, utilizing the lowenergy 4,000-hole collimator. Counts of 400,000 are obtained in one or two minutes with an intensity setting of 480. Further frontal examinations are performed at three-minute intervals for ten to twenty minutes until adequate visualization of the salivary glands occurs. When adequate visualization in the frontal position is obtained, oblique views are taken. The pinhole collimator, which has a higher degree of resolution than the low-energy collimator, is then used to obtain an enlarged image of the salivary glands. For these views centering is over the zygomatic arch in the 45 to 60° oblique position, with the neck moderately extended. The detector is positioned so that its face is 3 to 5 cm from the skin. The view obtained includes the parotid and submaxillary gland. Counts of 150,000 are obtained in three and one-half to five minutes with the intensity setting increased to 530. After views with the pinhole collimator are obtained for optimum anatomic detail, a frontal examination is performed with the 4,000-hole low-energy collimator. This is followed by stimulation of the salivary glands with lemon to promote emptying. Five minutes after stimulation frontal views are obtained to determine adequacy and symmetry of emptying, and restimula-tion is performed if necessary.