Rectilinear thyroid scanning as a predictor of malignancy.

Rectilinear scan findings were correlated with the surgically documented size, location, and histology of thyroid carcinoma in 67 patients. At the site of the carcinoma, 36 (54%) had hypofunction, associated with a palpable abnormality in all but one patient; 16 (24%) had an abnormality on palpation but not on scanning; 11 (16%) had both a normal clinical examination and a normal scan, associated with a benign abnormality in another part of the thyroid; and four (6%) had a patchy uptake. A literature review established that use of the gamma camera with pinhole collimator does not increase the specificity of carcinoma predictability, despite the enhanced sensitivity. The scan may still be used in evaluating the clinically solitary nodule that is not obviously malignant. However, unless that module is hyperfunctioning, clinical criteria rather than appearance of the scan should contribute most to the decision of whether to treat surgically.