Localizing prostate cancer in the presence of postbiopsy changes on MR images: role of proton MR spectroscopic imaging.
OBJECTIVE
To assess whether magnetic resonance (MR) spectroscopic imaging with MR imaging can improve prostate cancer localization in postbiopsy hemorrhage cases.


METHODS
Records of 175 patients with prostate cancer were retrospectively reviewed; 42 patients (135 hemorrhagic sites) had spatially correlated biopsy data. Patients underwent both phased-array coil-endorectal coil MR imaging and three-dimensional MR spectroscopic imaging within 180 days after transrectal ultrasound (US)-guided biopsy. High-signal-intensity hemorrhage on T1-weighted images and corresponding high- or low-signal-intensity areas on T2-weighted images and the metabolic ratio (choline + creatine)/citrate were recorded. Cancer was identified as a low-signal-intensity area at T2-weighted MR imaging or a metabolite ratio greater than 3 standard deviations above normal at MR spectroscopic imaging. MR imaging, spectroscopic, and biopsy findings were compared.


RESULTS
Forty-nine patients had postbiopsy hemorrhage. On T2-weighted images, a higher (P < .01) percentage of hemorrhagic sites demonstrated low signal intensity (80% [108 of 135 sites]), which is similar to the signal intensity seen with cancer. The addition of MR spectroscopic imaging to MR imaging resulted in a significant increase (P < .01) in the accuracy (52% to 75%) and specificity (26% to 66%) of tumor detection.


CONCLUSIONS
The addition of MR spectroscopic imaging to MR imaging significantly improves the ability to determine the presence of prostate cancer and spatial extent when postbiopsy changes hinder interpretation with MR imaging alone.
Kaji
Y
Y
Department of Radiology, University of California, San Francisco 94143-1290, USA.
Kurhanewicz
J
J
Hricak
H
H
Sokolov
D L
DL
Huang
L R
LR
Nelson
S J
SJ
Vigneron
D B
DB
D000368:Aged; D001706:Biopsy / Q000009:adverse effects*; D016022:Case-Control Studies; D006470:Hemorrhage / Q000209:etiology / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D011467:Prostate / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000473:pathology*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013997:Time Factors