The effect of gadolinium contrast media on radioiodine uptake by the thyroid gland.

OBJECTIVE: Patients with thyroid cancer may require detailed anatomic imaging before 131I therapy. Imaging by contrast-enhanced CT is contraindicated because it may result in saturation of tissues with iodine, decreasing the avidity of thyroid or thyroid cancer cells to subsequent radioiodine for extended intervals. Gadolinium-enhanced MRI offers an alternative to CT for detailed anatomic imaging. However, it is not known whether gadolinium contrast affects uptake of iodine by the thyroid gland since lanthanides affect ion transport in a variety of ways. The objective of this project was to determine whether the gadolinium MRI contrast injection alters thyroid uptake of radioiodine. METHODS: Radioiodine uptake by the thyroid gland was measured at 6 h and 24 h after the oral administration of 100 microCi 123I-Na-I. Three to seven days later, a standard dose (20 mL) of Magnevist (gadolinium DTPA) was administered intravenously. Another capsule of 100 microCi 123I Na-I immediately was given orally, and 6-h and 24-h radioiodine uptake by the thyroid gland was again measured and compared to baseline values. RESULTS: There was no statistically significant difference in uptake of radioiodine uptake by the thyroid gland between baseline values and those acquired immediately after the administration of Magnevist. CONCLUSION: Contrast-enhanced MRI may be safely performed before contemplated determinations of thyroid uptake of radioiodine, 131I therapy for hyperthyroidism, and postsurgical 131I imaging and therapy for well-differentiated thyroid cancer.

A double-blind study of perioperative steroid requirements in secondary adrenal insufficiency.

BACKGROUND: Patients treated long-term with supraphysiologic doses of glucocorticoids experience secondary adrenal insufficiency and are routinely given large doses of steroids in the perioperative period to prevent hypotension. Because the dose of steroids required to prevent hypotension is not known, we conducted a randomized, double-blind study to determine whether patients treated long-term with glucocorticoids actually require increased steroids in the perioperative period. METHODS: Patients who had been taking at least 7.5 mg prednisone daily for several months and had secondary adrenal insufficiency as defined by adrenocorticotropic hormone testing formed the study population. Patients were randomized to two groups. One group received perioperative injections of saline solution alone; the other received perioperative saline solution and cortisol. All patients received their usual daily prednisone dose throughout the study. RESULTS: Six patients were in the steroid-treated group and 12 were in the saline-treated group. Most subjects underwent major operations such as joint replacements, abdominal operations, and miscellaneous other procedures. Two patients had hypotension, one in each group. Hypotension resolved with volume replacement in both patients. The average pulse rates and blood pressures were similar in both groups during the perioperative period. CONCLUSIONS: Patients with secondary adrenal insufficiency do not experience hypotension or tachycardia caused by inadequate glucocorticoid levels when given only their daily dose of steroids for surgical procedures.

Detection of bile leakage from traumatic right hepatic duct laceration with technetium-99m DISIDA cholescintigraphy.

A woman was admitted to the hospital after blunt abdominal trauma. Initial ultrasound was equivocal but suggested a localized hepatic laceration. The patient was discharged but returned three weeks later with ascites and mild pain in the right upper abdominal quadrant. Hepatobiliary imaging identified a large bile leak originating from the porta hepatis but showed no evidence of parenchymal injury. No hepatic injury was found at surgery, but a laceration of the right hepatic duct was identified. Hepatobiliary imaging is the procedure of choice in diagnosing bile leaks from the extrahepatic biliary system.

Familial extra-adrenal pheochromocytoma. A new syndrome.

Pheochromocytomas in the same anatomic site, the right renal hilum, occurred in a family over three successive generations. For two patients in the latter two generations, scintigraphy with iodine 131-tagged metaiodobenzylguanidine (MIBG) showed tumors only in the region of the right renal hilum, thus indicating that they were primary lesions. At surgery, except for lymph node metastases noted microscopically in one patient, tumors were found only near the right renal hilum. The adrenal glands seemed normal on inspection, palpation, and computed tomography. In another family, a mother and son had primary pheochromocytomas arising from the urinary bladder. We suggest that primary extra-adrenal pheochromocytoma is a syndrome in which specific genetic abnormalities determine sites of tumor development.

Portrayal of pheochromocytoma and normal human adrenal medulla by m-[123I]iodobenzylguanidine: concise communication.

The radiopharmaceutical m-[131I]iodobenzylguanidine (I-131 MIBG), which is readily taken up by adrenergic vesicles, produces scintigraphic images of pheochromocytomas in man but rarely visualizes normal adrenal glands. Iodine-123 has many potential advantages over I-131 as a radiolabel for MIBG, including shorter half-life, freedom from beta emissions, and increased gamma-camera efficiency. In this study, diagnostic doses of MIBG labeled with I-131 and I-123, with nearly equivalent radiation dosimetry, were compared as imaging agents in eight patients with known or suspected pheochromocytoma. Images of superior quality were obtained with I-123 MIBG, and lesions not visualized using I-131 MIBG were portrayed. In addition, the normal adrenal medullae were visualized on the I-123 MIBG scintigrams in six out of eight patients.

Radiopharmaceutical treatment of malignant pheochromocytoma.

Apart from relieving effects of secreted catecholamines, treatments of malignant pheochromocytoma have achieved little success. When the radiopharmaceutical, meta-[131I] iodobenzylguanidine (I-131 MIBG ), was found to concentrate in some malignant pheochromocytomas, we calculated that this agent could impart therapeutic doses of radiation to these tumors. We therefore treated five patients with two to four doses of I-131 MIBG prepared in high specific activity, 8-11 Ci/mmol. Individual doses were given at 3- to 10-mo intervals and in 97- to 197-mCi amounts. Two patients exhibited subjective and objective benefits. Their tumors declined in size (to 28% and 30% of original volumes) and in hormone secretion (to 50% or less of baseline rates). The other three patients manifested few symptoms before treatment and showed few or no objective improvement afterward. The tumors of the patients who responded to I-131 MIBG (a) appeared to be more rapidly growing, (b) received more cumulative rads, and (c) were more predominantly in soft tissues (in contrast to bone) than those in the patients who obtained little benefit. No toxic effects were encountered during the treatments, and only minor and temporary untoward responses were seen later.