Experience in imaging medullary thyroid carcinoma using 99mTc (V) dimercaptosuccinic acid (DMSA)

99mTc (V) dimercaptosuccinic acid (DMSA) is a new tumor imaging agent that has been successfully used to image patients with medullary thyroid carcinoma (MTC). Since 1986, studies have been performed in 32 patients with histologically proven MTC at Guy's Hospital, London, England. Five patients with primary tumor were studied prior to surgery, four patients were studied after successful removal of the primary tumor, and 26 patients with biochemical evidence of recurrence were studied. Eight patients were studied serially to assess progression of disease, and four patients were studied before and after surgery. Twenty-one of the 26 patients with disease had positive scans with four false-negative scans and three true negative scans. One patient had a false-positive scan (sensitivity 80%, specificity 75%). Two of the false-negative scans were obtained in patients with moderate but stable elevations of calcitonin but no other evidence of recurrence. One false-negative scan was obtained in a patient who was discovered on screening to have an abnormal pentagastrin response, and a small 1 cm tumor was subsequently removed. Uptake in local neck recurrence was frequently intense, but uptake at sites of bone metastases was less marked. 99mTc (V) DMSA is an inexpensive radiopharmaceutical which produces good quality images and has been shown to have an acceptable sensitivity and specificity in the follow-up of patients with MTC and thereby contributes significantly to the management of these patients.