Absence of thyroid stunning after diagnostic whole-body scanning with 185 MBq 131I.

UNLABELLED: There has been recent controversy regarding the optimal protocol for imaging and ablation of post-thyroidectomy patients. Several authors have suggested that a scanning dose of 185-370 MBq (5-10 mCi) (131)I may be capable of producing a stunning effect on thyroid tissue that may interfere with the uptake and efficacy of the subsequent ablation dose of radioiodine. The purpose of this study was to determine whether a 185-MBq (5 mCi) diagnostic dose of (131)I produces a visually apparent stunning effect 72 h before (131)I ablation therapy. METHODS: One hundred twenty-two consecutive post-thyroidectomy patients for differentiated thyroid carcinoma received a 185-MBq (5 mCi) diagnostic dose of (131)I followed by a whole-body diagnostic scan at 72 h. On the same day the diagnostic scan was completed, the patient was admitted to the hospital and received an (131)I ablation therapy dose of 5550 MBq (150 mCi) in most cases. A postablation, whole-body scan was obtained at 72 h and compared with the previous diagnostic scan for any visual evidence of stunning. RESULTS: No cases of visually apparent thyroid stunning were observed on any of the postablation scans with regard to the number of (131)I foci identified or the relative intensity of (131)I uptake seen. CONCLUSION: Diagnostic whole-body scanning can be performed effectively with a 185-MBq (5 mCi) dose of (131)I 72 h before radioiodine ablation without concern for thyroid stunning.

The clinical utility of quantitative cholescintigraphy: the significance of gallbladder dysfunction.

PURPOSE: Cholelithiasis is a common disorder occurring in over 20 million people in the United States and resulting in approximately 600,000 cholecystectomies annually. Although over 95% of biliary tract disease is caused by gallstones, the vast majority (>80%) of cholelithiasis cases are asymptomatic. The purpose of this study is to evaluate the utility of quantitative cholescintigraphy in detecting symptomatic biliary tract disease and predicting clinical relief after cholecystectomy. MATERIALS AND METHODS: Fifty-two patients with clinical symptoms of chronic cholecystitis were evaluated by cholescintigraphy with a gallbladder ejection fraction calculated after the intravenous administration of cholecystokinin. A gallbladder ejection fraction of > or =35% was considered a normal physiologic response. Forty-one of the patients subsequently underwent cholecystectomy, whereas the remaining 11 subjects were diagnosed and treated for non-biliary disorders that did not require cholecystectomies. After clinical follow-up including histopathological gallbladder findings, all subjects' final diagnoses were established and correlated with their quantitative cholescintigram study. RESULTS: Twenty-six of twenty-eight patients who had an abnormal quantitative cholescintigram demonstrated evidence of chronic cholecystitis by histopathologic criteria after cholecystectomy. Furthermore, 27 of these 28 patients (96%) experienced complete relief of their clinical symptoms after surgery. CONCLUSION: Functional cholescintigraphy is a safe, accurate, and useful test for detecting symptomatic gallbladder disease, and appears reliable in predicting symptomatic relief after cholecystectomy.

The diagnostic utility of dual phase Tc-99m sestamibi parathyroid imaging.

PURPOSE: Primary hyperparathyroidism is a disease of uncertain etiology that results from hypersecretion of parathyroid hormone (PTH) by the parathyroid gland. In most institutions, the preferred imaging protocol utilizes a dual-phase technique with Tc-99m sestamibi which is reported to be more sensitive than earlier protocols involving TI-201 with Tc-99m pertechnetate subtraction. The purpose of this study is to evaluate the accuracy and clinical utility of Tc-99m sestamibi dual-phase scintigraphy for localizing hyperfunctioning parathyroid tissue. MATERIALS AND METHODS: We retrospectively reviewed thirty-nine consecutive hyperparathyroid patients who received a dual-phase Tc-99m sestamibi parathyroid scan. Thirty-seven of the subjects subsequently underwent a bilateral neck exploration and parathyroidectomy. Each scan interpretation was then correlated with the histopathologic diagnosis and the patients' post-surgical clinical course. RESULTS: The sestamibi dual-phase imaging protocol correctly localized 21 of 25 parathyroid adenomas and identified 8 out of 10 cases of hyperplasia. Our overall sensitivity and specificity were 83% and 75%, respectively. In addition, four of the adenomas were successfully localized intraoperatively using a gamma probe. CONCLUSION: Parathyroid imaging with sestamibi appears to be superior to TI-201/Tc-99m pertechnetate subtraction based on the reported results of both techniques at various institutions. Dual-phase sestamibi imaging appears to be useful and cost-effective for presurgical localization of hyperfunctioning parathyroid tissue. In addition, sestamibi imaging in conjunction with an intraoperative probe is a very promising technique that has the potential to provide both localization information of a suspected parathyroid adenoma and to facilitate its surgical removal by reducing operation time.

Asymmetry of basal ganglia perfusion in Tourette's syndrome shown by technetium-99m-HMPAO SPECT.

UNLABELLED: Our study involved performing brain perfusion SPECT scans on Tourette's subjects to observe any common perfusion abnormalities involving the cerebral cortex or subcortical structures. METHOD: Six patients with Tourette's syndrome and nine normal control subjects underwent a brain SPECT study with 99mTc-HMPAO. Regions of interest were generated over the cerebral cortex, basal ganglia, thalamus and cerebellum to evaluate any relative perfusion abnormalities or asymmetry in the Tourette's subjects. RESULTS: Five of the six Tourette's subjects demonstrated a significant decrease in right basal ganglia activity which was not present in any of the normal control subjects. CONCLUSION: Our study suggests an etiology for Tourette's syndrome involving the right basal ganglia. Furthermore, brain SPECT may be useful in the evaluation of these patients if it proves to be sufficiently sensitive and specific in larger study populations.

The usefulness of the dynamic phase in pertechnetate thyroid imaging for solitary hypofunctioning nodules.

One hundred patients, each with a solitary thyroid nodule detected by clinical palpation, underwent three-phase Tc-99m pertechnetate thyroid imaging. The degree of perfusion of the thyroid nodule was classified as hypo-perfused, euperfused, or hyperperfused compared to the remainder of the gland by a consensus of three nuclear medicine physicians. The nodules were subsequently biopsied, and the degree of perfusion of the nodules was correlated with their histologic diagnosis. Twenty-two nodules were classified as hyperperfused, 64 as euperfused, and 14 as hypoperfused. Malignancy rates of the hyperperfused, euperfused, and hypoperfused nodules were 36%, 31% and 0%, respectively. This seems to indicate that malignant thyroid nodules demonstrate a degree of perfusion at least equal to or greater than the rest of the thyroid gland. Conversely, none of the hypoperfused nodules was found to be malignant. The perfusion phase of thyroid imaging may provide useful clinical information regarding possible malignancy of a thyroid nodule.

Effects of visual stimulation on the redistribution of iodine-123-IMP in the brain using SPECT imaging.

A study was performed to validate the assumption that redistribution and clearance of [123I]IMP localization in the brain are unaffected by changes in ambient light levels and visual stimulation occurring after radiopharmaceutical is administered and deposited in the brain. Serial SPECT and planar imaging studies were performed on six healthy, volunteer, adult male subjects under resting, nonactivation conditions. Studies were repeated 7 days later with each subject exposed to strobe light stimulation prior to delayed SPECT procedures at 3 hr. Redistribution and clearance of 123I-IMP in the brain were examined in cortical, subcortical, and cerebellar regions on transaxial slices for the two sets of serial procedures in each subject. Visual stimulation following the initial uptake of [123I]IMP did not affect the distribution or clearance of [123I]IMP in the brain, including the visual cortex, and therefore should not influence the interpretation of delayed SPECT images.