SUPERIORITY OF SPET TO PLANAR IMAGING IN THE DETECTION OF COLORECTAL CARCINOMAS WITH IN-111 MONOCLONAL-ANTIBODIES

The aim of this study was to assess the contribution of single photon emission tomography (SPET) to planar imaging of colorectal carcinoma i n patients being evaluated with In-111-labelled monoclonal antibodies CYT-103 (OncoScint CR/OV) or IVP ZCE 025. Planar and SPET scans from 1 10 colorectal carcinoma patients were scored individually as follows: 1=negative, 2=equivocal, 3=positive. The planar and SPET images identi fied 67 and 93 of 113 documented lesions, respectively. The planar and SPET findings were concordant in 55 patients. SPET converted planar f indings from 1 to 3 in 11 patients and from 2 to 3 in 21 patients. SPE T provided a better definition of the extent of the tumour in 21 patie nts. Both imaging tests were true-negative in five patients, and faile d to detect tumours in six patients. We strongly recommended SPET in a ll patients undergoing immunoscintigraphy, since it identified tumours missed on planar scans in 35% of patients and provided additional inf ormation regarding tumour burden in 23% of patients.