RADIONUCLIDE ANGIOGRAPHY IN EVALUATION OF COLD SOLITARY THYROID-NODULES - IMPROVED DIAGNOSTIC-ACCURACY USING FLOW AND WASHOUT ANALYSIS

Radionuclide thyroid angiography was performed in 252 patients with hy pofunctioning thyroid nodules to evaluate differences in vascular flow and washout patterns in benign and malignant disease. Time activity c urves of Tc-99m pertechnetate flow through the cold nodules were gener ated using region of interest software. Retention ratios of counts in the nodule at 2 minutes after radionuclide administration versus those at peak activity were derived. Patients subsequently underwent surgic al excision and histopathologic examination. One hundred forty-four of the 204 benign nodules were avascular with absent radionuclide flow t hrough the nodule. Fifty-six benign nodules were vascular with a prolo nged radionuclide washout pattern with retention ratios ranging from 0 .60-0.92. Forty-six of the 48 malignant nodules displayed increased pe rfusion with rapid radionuclide washout with retention ratios ranging from 0.28-0.48. Four benign nodules exhibited a similar flow and washo ut pattern, Radionuclide thyroid angiography with vascular flow and wa shout analysis appears to be a useful technique to differentiate betwe en benign and malignant thyroid nodules with a high degree of sensitiv ity and specificity.