First evaluations of PET/MRI in gynaecological malignancies

Objectives To assess and to compare the diagnostic accuracy of PET/CT and PET/MRI in primary and metastatic gynaecological malignancies.

Methods 13 patients (mean age: 64) with primary and recurrent gynaecological diseases underwent a contrast-enhanced tri-modality PET/CT-MRI examination (PET/CT D 690 and 3T MRI 750W). Patients were first injected with an average of 320 MBq F18-FDG and then rested for 30 minutes. Then, a full diagnostic, contrast-enhanced MRI of the abdomen and pelvis was acquired with the following sequences: coronal T2 SSFSE pelvis, axial T2 SSFSE liver, axial T1 LaveFlex whole abdomen, axial diffusion pelvis, sagittal/axial T2 propeller pelvis, sag/axial T1 LavaFlex post contrast whole abomden. After the MRI, patients were transferred on a dedicated shuttle to the PET/CT. Here, a standard PET/CT with /without intravenous contrast media was acquired. All data were evaluated on a commercially available workstation and can be displayed as PET, CT, PET/CT and PET/MRI. PET/MRI and PET/CT were evaluated concerning detection and conspicuity of the primary tumor, lymph node metastases and distant metastases. Readers also evaluated if the PET/MRI revealed relevant additional information compared to PET/CT.

Results Concerning the primary tumour, the PET/CT was superior in 2 , PET/MRI in 5 cases, concerning lymph nodes PET/CT was superior in 2 , PET/MRI in 2 cases, in abdominal metastases PET/CT was superior in 2 , PET/MRI in none. PET/CT overall showed additional relevant additional information in 9 cases concerning distant metastases, PET/MRI showed relevant additional information in 3 cases concerning the primary tumour.

Conclusions PET/MRI shows mainly advantages concerning the evaluation of the pimary tumor/local pelvic situation while the PET/CT has advantages concerning distant metastases. PET/MRI with whole body imaging has to be evaluated concerning the differences in distant metastases detection.