Impact of Fusion of Indium-111 Capromab Pendetide Volume Data Sets with Those from MRI or CT in Patients with Recurrent Prostate Cancer

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Abstract
OBJECTIVE. Our goal was to evaluate the impact of image fusion on the interpretation of indium-111 Prosta-Scint SPECT scans. MATERIALS AND METHODS. Sixty-seven consecutive patients referred for rising prostate-specific antigen (PSA) levels after initial therapy for primary prostate cancer underwent SPECT 96 hr after infusion of 111In Prosta-Scint, with simultaneous technetium-99m blood pool imaging. Volume data sets from the SPECT scans were then fused with those from CT and MR images of the pelvis using a 3D landmark-based warping program. The SPECT scans were initially interpreted without benefit of MRI or CT fusion. The fused Prosta-Scint MRI-CT volumes were reevaluated by a nuclear radiologist and an MRI radiologist. Independent reviews before and after fusion were available in these patients. Validation of results after fusion was performed through correlation with PSA changes after radiation therapy. RESULTS. Six patients with sites that could not be evaluated and three without their original Prosta-Scint scanning reports were excluded; thus, 58 patients were studied clinically. Seventy-four of 161 prefusion-positive sites were found to be negative after fusion. These 74 sites subsequently were identified primarily as showing bowel, vessel, or marrow uptake after fusion. In two patients, nodal disease was identified although the review before perfusion indicated none. Twenty-five patients previously thought to have nodal disease appeared to have only local disease after fusion. After local radiation therapy, PSA levels decreased in 12 of 25 patients, increased in five, and were unavailable in eight. CONCLUSION. Although Prosta-Scint SPECT alone can help in the proper management of recurrent prostate cancer, fusion with MRI-CT of the pelvis can improve the specificity of the examination.