COMPARISON OF F-18 FLUORODEOXYGLUCOSE POSITRON-EMISSION-TOMOGRAPHY AND TC-99M METHOXYISOBUTYLISONITRILE SCINTIMAMMOGRAPHY IN THE DETECTION OF BREAST-TUMORS

The aim of this study was to compare, in breast cancer patients, the d iagnostic accuracy of positron emission tomography (PET) using fluorin e-18 fluorodeoxyglucose (FDG) and scintimammography (SMM) using techne tium-99m methoxyisobutylisonitrile (MIBI). A total of 20 patients (40 breasts with 22 lesions) were evaluated serially with MIBI and, on the following day, with FDG, For SMM, planar and single-photon emission t omography imaging in the prone position was performed starting at 10 m in following the injection of MIBI (740 MBq), For PET, scans were acqu ired 45-60 min after the injection of FDG (370 MBq) and attentuation c orrection was performed following transmission scans. Results from SMM and PET were subsequently compared with the histopathology results, T rue-positive results were obtained in 12/13 primary breast cancers (me an diameter=29 mm, range 8-53 mm) with both FDG and MIBI. False-negati ve results were obtained in two local recurrences (diameter <9 mm) wit h both FDG and MIBI. In benign disease, FDG and MIBI did not localize three fibrocystic lesions, two fibroadenomas and one inflammatory lesi on (true-negative), but both localized one fibroadenoma (false-positiv e). Collectively, the results demonstrate a sensitivity of 92%. and a specificity of 86%, for primary breast cancer regardless of whether FD G or MIBI was used. In contrast to MIBI scintigraphy, FDG PET scored t he axillae correctly as either positive (metastatic disease) or negati ve (no axillary disease) in all 12 patients. The tumour/non-tumour rat io for MIBI was 1.97 (range 1.43-3.1). The mean standard uptake value (SUV) for FDG uptake was 2.57 (range 0.3-6.2). The diagnostic accuracy of SMM was equivalent to that of FDG PET for the detection of primary breast cancer, For the detection of in situ lymph node metastases of the axilla, FDG seems to be more sensitive than Tc-99m-MIBI.