ASSESSMENT OF RESIDUAL TUMOR VIABILITY IN THYMIC CARCINOMA BY SEQUENTIAL TL-201 SPECT - COMPARISON WITH CT AND BIOPSY FINDINGS

We present a case of Tl-201 accumulating thymic carcinoma, in which se quential CT scans demonstrated a steady decrease in tumor volume. The presence of a residual mass on CT scans after the completion of therap y presented the clinical dilemma of whether or not a viable tumor rema ined. Sequential Tl-201 SPECT images demonstrated a marked decrease in tumor uptake. At 2 wk after therapy, no significant accumulation of T l-201 in the region of the residual mass was observed, indicating a la ck of viable tumor. A biopsy specimen revealed no tumor cells. Sequent ial histopathologic findings were correlated well with the findings of Tl-201 SPECT lather than those of CT. Thallium-201 SPECT is of great clinical value in assessing tumor viability in the course of therapy.