Usefulness of diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance imaging in the diagnosis of prostate transition-zone cancer.
BACKGROUND
Conventional T2-weighted (T2-WI) magnetic resonance imaging (MRI) has poor sensitivity for prostate transition-zone (TZ) cancer detection.


OBJECTIVE
To retrospectively evaluate the clinical value of diffusion-weighted MRI (DW-MRI) and dynamic contrast-enhanced MRI (DCE-MRI) in combination with T2-WI for the diagnosis of TZ cancer.


METHODS
Twenty-six TZ cancers in 23 patients with at least one tumor (tumor size >10 mm) located predominantly in the TZ were included in the study. Sixteen peripheral-zone (PZ) cancers in 12 patients with PZ cancer but without TZ cancer (control group) were selected by step-section pathologic maps. All patients underwent MRI and radical prostatectomy. MRI was obtained by a 1.5T superconducting system with a phased-array coil. Imaging sequences were T2-WI with fat saturation (FST2-WI), DW-MRI (single-shot echoplanar image, b=0 and 1000 s/mm(2), apparent diffusion coefficient [ADC] map findings), and DCE-MRI (3D fast spoiled gradient recalled [SPGR], contrast medium [0.2 mmol/kg], total injection time 5 s, image acquisition 30, 60, and 90 s). Sensitivity, specificity, accuracy, and positive predictive value (PPV) for the diagnosis of TZ cancer were evaluated in four protocols: A) FST2-WI alone, B) FST2-WI plus DW-MRI, C) FST2-WI plus DCE-MRI, D) FST2-WI plus DW-MRI plus DCE-MRI.


RESULTS
Sensitivity, specificity, accuracy, and PPV in protocol A (FST2-WI alone) were 61.5%, 68.8%, 64.3%, and 76.2%, respectively. FST2-WI plus DW-MRI (protocol B) improved the sensitivity, specificity, accuracy, and PPV. In FST2-WI plus DW-MRI plus DCE-MRI (protocol D), the number of true-negative lesions increased and false-positive lesions decreased, and the sensitivity, specificity, accuracy, and PPV were 69.2%, 93.8%, 78.6%, and 94.7%, respectively. There was a significant difference between protocols A and D (P<0.05).


CONCLUSIONS
Adding DW-MRI to FST2-WI in the diagnosis of prostate TZ cancer increased the diagnostic accuracy. The addition of DCE-MRI may be an option to improve the specificity and PPV of diagnosing TZ cancer with FST2-WI and DW-MRI.
Yoshizako
T
T
Department of Radiology, Shimane University Faculty of Medicine, Shimane, Japan. yosizako@med.shimane-u.ac.jp
Wada
A
A
Hayashi
T
T
Uchida
K
K
Sumura
M
M
Uchida
N
N
Kitagaki
H
H
Igawa
M
M
D000230:Adenocarcinoma / Q000175:diagnosis* / Q000601:surgery; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D011467:Prostate / Q000473:pathology / Q000601:surgery; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000601:surgery; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D003287:Contrast Media; D019786:Gadolinium DTPA