Prostate cancer detection with MRI: is dynamic contrast-enhanced imaging necessary in addition to diffusion-weighted imaging?
OBJECTIVE
To assess the feasibility of using magnetic resonance imaging for prostate cancer detection without using a contrast material.


METHODS
T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced imaging (DCEI) were performed using a phased-array coil at 1.5 T. These examinations were performed in 178 patients with elevated serum prostate-specific antigen levels ( > 4.0 ng/mL) before systematic needle biopsy. Two radiologists independently evaluated images from DWI, DCEI, and a combination of the two techniques by referring to a T2WI image and by using a predefined confidence scale for cancer detection. The right and left halves of the peripheral zone and the central gland were separately rated. The diagnostic performance (A < sub > z < /sub > ) of each technique was assessed by analyzing their associated area under the receiver operating characteristic curves. The results of a biopsy served as a reference standard.


RESULTS
Prostate cancer was detected in 72 (40.4%) of the 178 patients. For the entire prostate, the diagnostic performances of DWI (Az = 0.848) (P < 0.001) and the combined technique (Az = 0.845) (P < 0.001) were significantly more accurate than that of DCEI (Az = 0.746). DWI (74.8%) (P < 0.001) and the combined technique (72.9%) (P < 0.001) were significantly more sensitive than DCEI (52.8%). The numbers of cancer lesions that were interpreted using only DWI or DCEI were 83 (26.1%) and 13 (4.1%) of the 318 study lesions, respectively.


CONCLUSIONS
DWI and the combined technique are more accurate and sensitive than DCEI in the detection of prostate cancer; however, DWI and DCEI play complementary roles in the accurate detection of prostate cancer.
Iwazawa
Jin
J
Department of Radiology, Nissay Hospital, Osaka, Japan. iwazawa.jin@nissayhp.or.jp
Mitani
Takashi
T
Sassa
Seitaro
S
Ohue
Shoichi
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D016001:Confidence Intervals; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005240:Feasibility Studies; D019786:Gadolinium DTPA; D006801:Humans; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods; D015588:Observer Variation; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000473:pathology*; D011856:Radiographic Image Enhancement; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D003287:Contrast Media; D017430:Prostate-Specific Antigen; D019786:Gadolinium DTPA