Diagnostic Accuracy of MRI/MRSI for Patients with Persistently High PSA Levels and Negative TRUS-Guided Biopsy Results
Cathleeyakorn Bhatia MD*, Sith Phongkitkarun MD*, Dechaphol Booranapitaksonti MD**, Wachira Kochakarn MD**, Panas Chaleumsanyakorn MD***
Affiliation : * Department of Radiology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University ** Department of Surgery, Faculty of Medicine, Ramathibodi Hospital, Mahidol University *** Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University
Objective : To prospectively evaluate the accuracy of transrectal ultrasonographic (TRUS)-guided biopsies
by using combined magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI)
in patients with persistently high prostate-specific antigen (PSA) levels and negative TRUS-guided biopsy
results.
Materials and Methods : Twenty-one patients (age range 50-77 years, average 61.4 years) with negative TRUS
biopsy were enrolled. Suspicious areas were identified by discrete low signal intensity in T2 on standard MRI.
MRSI was interpreted by using spectral approach and given score of 1 (benign) to 5 (malignant). Suspicious
voxels were localized for guided TRUS biopsy. All patients underwent sextant TRUS biopsies with up to four
additional biopsies targeted at suspicious sites. Diagnostic accuracy of MRI/MRSI in patient-by-patient and
voxel-by-core were analyzed.
Results : Prostate cancer was detected in 2 of 21 patients (9.5%). The sensitivity, specificity, PPV, NPV, and
accuracy of combined MRI/ MRSI for detection of prostate cancer were 100%, 84%, 40%, 100%, and 86%,
respectively. The site of positive biopsy correlated correctly with voxels were 80%, 85%, 21%, 99% and 85%
on sensitivity, specificity, PPV, NPV and accuracy, respectively.
Conclusion : MRI/ MRSI have the potential to guide biopsy to cancer foci in patients with persistently high
PSA levels and prior negative TRUS biopsy results.
Keywords : Prostate cancer, Magnetic resonance imaging, Spectroscopic imaging, Transrectal ultrasonography
