Ji Hye Min, Presenter: Nothing to Disclose

Chan Kyo Kim MD, Abstract Co-Author: Nothing to Disclose

Ji Hyun Koo MD, Abstract Co-Author: Nothing to Disclose

Byung Kwan Park MD, Abstract Co-Author: Nothing to Disclose

Dongil Choi MD, Abstract Co-Author: Nothing to Disclose

Bohyun Kim MD, Abstract Co-Author: Nothing to Disclose

Ghee Young Kwon, Abstract Co-Author: Nothing to Disclose

To determine the optimal b value of 3-T diffusion-weighted MR imaging (DWI) in the prediction of localized prostate cancer, and to evaluate the utility of DWI under different b values in differentiating between the cancers and benign prostatic tissue.

80 consecutive patients with suspected prostate cancer underwent T2-weighted imaging (T2WI) and DWI at 3T using a phased-array coil, followed by radical prostatectomy. DWI was examined with single-shot echo-planar imaging sequence under different b values. Apparent diffusion coefficient (ADC) maps were generated by two b values (i.e., b= 0 and another b value of 300, 700, 1000 or 2000 s/mm2). For predicting the cancer location, the prostate was divided into 10 regions and based on the anatomical details of T2WI, ADC maps at b= 300 (ADC1), 700 (ADC2), 1000 (ADC3) and 2000 (ADC4) s/mm2 were analyzed independently by two blinded readers (experienced and less-experienced) using a five-point scale and the results were compared. ADC values were measured in benign and malignant tissues in the peripheral zone (PZ) or transition zone (TZ). The results at ADC maps of each b value were correlated with step-section histopathologic findings.

For predicting 102 prostate cancers, the sensitivity in the experienced reader was significantly greater at ADC3 (84.9%) than at ADC1 (35.1%), ADC2 (78%) or ADC4 (74.1%) (P< 0.01). However, the specificity was similar at all b values, with at least 92%. In the experienced reader, the area under the curve (Az) in order from ADC1 to ADC4 was 0.689, 0.877, 0.91 and 0.866, respectively and that of ADC3 showed a significant difference as compared with the others. In the less-experienced reader, the Az value of ADC2 (0.646), ADC3 (0.652) or ADC4 (0.636) was significantly greater than that of ADC1 (0.589) (P< 0.01). The mean ADC value of the cancers in order from ADC1 to ADC4 was 1.34 ± 0.33, 1.03 ± 0.23, 0.83 ± 0.21 and 0.68 ± 0.15 × 10-3mm2/s, respectively, which were significantly lower than that of benign PZ or TZ (P< 0.001).

For predicting the prostate cancer, the optimal b value for 3-T DWI was found to be 1000 s/mm2. Furthermore, 3-T DWI under different b values could differentiate the cancers and benign prostate tissue.

With the application of the optimal b value of 1000 s/mm2, 3-T DWI using a phased-array coil can improve the diagnostic performance for the evaluation of prostate cancer.

Min, J, Kim, C, Koo, J, Park, B, Choi, D, Kim, B, Kwon, G, Diffusion-weighted MR Imaging for the Evaluation of Prostate Cancer: Optimization of B Value at 3 T.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9013187.html