Delayed Tc-Tetrofosmin scintigraphy is a highly sensitive and specific method for characterizing solitary thyroid nodules, while color Doppler has a low sensitivity but relatively high specificity in differentiating benign from malignant thyroid lesions.

The aim of this study was to evaluate the potential of Tc-99m citrate as a new tumor-localizing agent in palpable breast masses. Scintimammography was performed in 43 female patients. Of these, 10 women (group A) were considered to be healthy with no palpable breast masses, and the remaining 33 patients (group B) had palpable breast masses. All patients with palpable breast masses underwent fine-needle aspiration cytology and subsequent biopsy within 2 weeks of the study. Nine patients had a primary malignant lesion of the breast, whereas 24 patients had benign disease. The patients with breast cancer underwent surgery, and subsequently a histopathologic diagnosis was made. Sensitivity, specificity, and accuracy values obtained in our study were 87%, 100%, and 90%, respectively. Scintimammograms were performed in these patients up to 24 hours. Initial uptake at 1 and 3 hours was noted in all the breast masses. However, benign masses did not show persistence of tracer uptake at 24 hours, whereas those that were malignant continued to show persistent radionuclide concentration. Thus, the uptake and outflow pattern seemed to differentiate benign breast disease from breast cancer. The study shows the potential of Tc-99m citrate for imaging and evaluating breast masses.

Pancake kidney is an extremely rare renal anomaly resulting from abnormal renal ascent and subsequent fusion. The authors describe a patient with pancake kidneys detected on a Tc-99m DTPA scan. The case reported depicts the scintigraphic findings in such a patient having a pancake kidney.

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The authors present a prospective analysis of Tc-99m MDP and Tc-99m citrate scintigraphy in 108 patients with known malignant or degenerative benign bone disease. Of 108 patients, 59 (group A) had malignant bone disease. The other 49 patients (group B) had degenerative benign bone disease for which the results of Tc-99m MDP scans were positive. In both groups the Tc-99m citrate scan was performed 1 week after the Tc-99m MDP scan. The Tc-99m citrate/Tc-99m MDP lesion-to-background radioisotope uptake ratio (RUR) was calculated for each lesion 3 hours after radionuclide administration. The mean RUR for the malignant lesions was 1.0 +/- 0.484; for the benign lesions, the RUR was 0.29 +/- 0.250. Static imaging was also done for 10 lesions each from the malignant and benign groups at 1, 3, and 24 hours to study the kinetics of Tc-99m citrate. Time-activity curves for malignant lesions showed that the RUR remained high for 24 hours, whereas benign lesions showed a drastic decrease at 3 and 24 hours compared with the 1-hour images. The ratio of Tc-99m citrate to Tc-99m MDP is a promising parameter to differentiate malignant from benign degenerative lesions seen as areas of increased activity on Tc-99m MDP bone scans. The sensitivity and specificity of this technique were 97.8% and 95%, respectively.