Abstract
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Objectives Detecting and staging prostate cancer by common urological and imaging techniques is still inadequate leading to unnecessary false negative needle biopsies and, where the result is positive, often to a less than ideal choice of therapy. This study was conducted to investigate the improvement in the rate of detection of local tumor foci and tumor staging by combining the high detection rate of PET with radiolabelled choline and the high local resolution of T2-weighted endorectal MRI.
Methods Open, prospective, controlled, single-arm, single-treatment, single center design (EudraCT-No. 2006-003933-33). Patients with prostate cancer confirmed by needle biopsy, scheduled for radical prostatectomy, obtained a FEC-PET and endorectal MRI in identical position (modular table system, software fusion by Na-22-PET/MRI-landmarks, bladder catheter). After radical prostatectomy on the next day, the entire organ was histologically reconstructed in holoptical sections followed by lesion based correlation with FEC-PET/MRI, PET and MRI separately. FEC pos. lesions were considered to be malignant in PET analysis.
Results In 38 patients FEC-PET/MRI had a lesion based ppv/sensitivity/specificity/accuracy of 86%/66%/69%/67%, MRI 83%/48%/69%/53%, PET 69%/71%/0% (due to study design)/54%; in patients with Gleason >6: PET/MRI 96%/87%/80%/86%, MRI 96%/73%/80%/74%, PET 84%/90%/0%/77%; sensitivity for lesions >5mm PET/MRI 84%, MRI 67%, PET 85%. PET/MRI prediction of organ confirmed tumor stage (T2a-c): 61%; T3a (microfocal&extensive): 33%; T3a (extensive): 100% (n=5); pT3b: 71%.
Conclusions FEC-PET/MRI demonstrates a high positive prediction of prostate cancer foci and should be the method of choice for planning needle biopsies. Cancer foci above the scanner's spatial resolution as well as the more aggressive tumors >Gleason 6 are identified reliably. The clinically important extensive extracapsular tumor growth and the infiltration of seminal vesicles were predicted correctly in almost all cases. Microfocal capsular infiltration designates the limit of this method