| Part I The Diagnostic Value of Diffusion Weighted MR Imaging in Prostate CancerPURPOSE:To evaluate the diagnostic value of diffusion weighted MR imaging in prostate cancer using 3.0T MR.MATERIALS AND METHODS:Seventy-four patients with suspected prostate cancer underwent DWI (b=0,800) using 3.0 T MR. The apparent diffusion coefficient (ADC) values of all patients were measured by a radiologist unaware of the pathological results. The mean values of the low-value region in ADC map in bilateral peripheral zones (PZs) were measured respectively and recorded as the low-ADC values. The PZs were divided into positive group (with prostate cancer) and negative group (with no evidences of cancer) according to the pathological results of transrectal ultrasound (TRUS)-guided biopsy. The low-ADCs were compared between the positive group and the negative group, as well as between the well-differentiated cancer (Gleason Score 2-6) and the poor-differentiated cancer (Gleason Score 7-10) using t test (SPSS 17.0). A P value of less than 0.05 was considered to indicate a statistically significant difference.RESULTS:In the 74 patients,146 PZs were pathologically examined,50 PZs were classified into negative group (15 with nomoral tissue,28 with BPH,7 with inflammation), and 96 PZs were classified into positive group (17 with well-differentiated cancer,79 with poor-differentiated cancer). The low-ADC was 0.92x10-3±0.22×10-3mm2/s for the positive group and 1.48×10-3±0.28×10-3mm2/s for the negative group, significant difference was noted between the two groups (t=12.27, P=0.00). In addition, statistical difference of low-ADC were also noted between the PZs with well-differentiated cancer (1.04×10-3±0.20x10-3 mm2/s) and the PZs with poor-differentiated cancer (0.89x10-3±0.21×10-3 mm2/s) (t=2.60, P=0.01), as well as between the PZs with well-differentiated cancer and the negative group (t=5.91, P=0.00). The area under the ROC curve was 0.95 (P=0.00); the best threshold of low-ADC for the diagnosis of prostate cancer was 1.15×10-3mm/s, the diagnostic sensitivity and specificity were of 85.4%and 92.0%, respectively.CONCLUSION:The values of low-ADC in PZS are useful in diagnosing prostate cancer. The low-ADC less than 1.15×10-3 mm2/s is a preferable threshold to differentiate prostate cancer from non-cancerous tissue in our study. PartⅡThe Diagnostic Value of MR Spectroscopic Imaging in Prostate CancerPURPOSE:To evaluate the diagnostic value of body coil acquired MR spectroscopy imaging in prostate cancer using 3.0T MR.MATERIALS AND METHODS:Fourty-one patients with suspected prostate cancer underwent body coil acquired MRS using 3.0T MR. The CC/Ci values were measured by a radiologist unaware of the pathological results. The mean values of the CC/Ci in the hot region of the CC/Ci map of bilateral PZs were calculated respectively, and recorded as the high-CC/Ci of the identical sides. The PZs were divided into positive group (with prostate cancer) and negative group (with no evidence of cancer) according to the result of TRUS-guided biopsy. The high-CC/Ci values were compared between the positive group and the negative group, as well as between the benign prostate hyperplasia (BPH) and the inflammation using SPSS 17.0. A P value of less than 0.05 was considered to indicate a statistically significant difference.RESULTS:In 41 patients,80 PZs were pathologically confirmed. Thirty-one PZs were classified into negative group, including BPH (n=19), inflammation (n=6), and nomal tissue (n=6). Forty-nine were classified into positive group (Gleason score 2-6, 3 cases; Gleason score 7-10,46 cases). The high-CC/Ci value was 1.75±1.78(median±interquartile range, IQR)for the positive group and 0.65±0.32 for the negative group, there was significant difference between them (P=0.00). There was no statistica difference (P=0.61) of high-CC/Ci values between the BPH (0.78±0.32) and the inflammation (0.65±0.23). The area under the ROC curve was 0.93 (P=0.00); when the threshold of CC/Ci was 0.98, the diagnostic sensitivity and specificity were of 91.8%and 93.5%, respectively.CONCLUSION:Body coil acquired MRS using 3.0T MR is useful in predicting the positive of prostate cancer in TRUS-guided aspiration. The ratio of CC/Ci higher than 0.98 is a preferable threshold in differentiating prostate cancer from non-cancerous tissue in our study. PartⅢThe Characteristics of Prostate Cancer in Dynamic Contrast-Enhanced MR ImagingPURPOSE:To investigate the enhancing characteristics of prostate cancer, and to evaluate the diagnostic value of dynamic contrast-enhanced MR imaging (DCE-MRI) in prostate cancer using 3.0T MR.MATERIALS AND METHODS:Fourty-four patients with suspected prostate cancer underwent DCE-MRI. The image was analyzed for both PZs by a radiologist unaware of the pathological results with Functiontoll (ADW 4.2). The shapes of signal intensity-time (SI-T) curve were defined as type A (persistently and slowly ascending curve), type B (slowly ascending followed with plateau curve), type C (rapidly ascending followed with plateau curve), and type D (rapidly ascending followed with descending curve). The calculated indexes include the whole enhancement degree (SIpeak%) and the relative maximum slope (Rmax). The PZs were divided into positive group (with prostate cancer) and negative group (with no evidence of cancer) according to the results of TRUS-guided biopsy. The styles of SI-T curve of the positive group and the negative group were analyzed, respectively; and enhancement indexes were compared between these two groups as well as between well-differentiated cancer and poor-differentiated cancer using SPSS 17.0. Differences with a P value less than 0.05 were considered statistically significant.RESULTS:In 44 patients,87 PZs were phathologically proved,34 were classified into negative group (4 with nomoral tissue,21 with BPH,9 with inflamation), and 53 were classified into positive group (7 with good-differentiated cancer,46 with poor-differentiated cancer). The most common styles of SI-T curve in positive group were type C (49.06%) and type D (32.08%). The most common style of SI-T curve in negative group was type D (70.59%). The SIpeak% and Rmax were 2.04±0.52 and 35.09±15.79 for positive group; and were 1.38±0.55,17.39±9.69 for negative group. There were significant differences between these two groups (P=0.00, P=0.00). In addition, SIpeak%and Rmax were 1.55±0.54,21.20±14.97 for the well-differentiated cancer and 2.12±0.48,37.20±14.95 for the poor-differentiated cancer, significant differences were noted between them (P=0.01, P=0.01).CONCLUSION:DCE-MRI is helpful in differentiation diagnosis of prostate cancer. The early rapidly increase of SI observed in SI-T curve is common in prostate cancer, and the persistently and slowly ascending of SI observed in SI-T curve is common in non-cancerous tissue. Part VI Diffusion-Weighted MR Imaging in Assessment of Tumor Response to Radiotherapy in Patients with Prostate CancerPURPOSE:To investigate the changes of diffusion-weighted MR imaging in PZs after intensity modulated radiotherapy (IMRT) in patients with prostate cancer using 3.0 T MR, and assess the value of DWI in monitoring the response to radiotherapy and early predicting the prognosis of patients.MATERIALS AND METHODS:Twenty-three patients with histopathologically proven prostate cancer received IMRT in our hospital from Apr 2008 to Jun 2009. All patients accepted the TRUS-guided biopsy, among the 46 PZs,33 were proved cancer (8 good-differentiated cancer,25 poor-differentiated cancer), and 13 had no evidences of cancer. DWI (b=0,800) was performed within one month before and within 2 months after the radiotherapy using 3.0T MR. The ADC were measured at 3 consecutive slices in both PZs respectively, before and after the radiotherapy. The ADC change was calculated by the post-radiotherapy ADC minus the pre-radiation ADC. Clinic follow-up were performed after radiotherapy till to Mar 2010, patients had diseases progression or biometablic relapse were defined as poor-effect, or else were defined as goog-effect.RESULTS:There were 138 slices of ADC in 46 PZs measured. In the clinic follow-up after radiotherapy till to Mar 2010,4 patients were defined as poor-effect, the others (n=19) were defined as goog-effect. There was no statistica difference (P=0.39) between the good-effect group and the poor-effect group in the pre-radiation ADC (1.42x10-3±0.20×10-3mm2/s vs 1.39x10-3±0.19×10-3mm2/s). However, there was significant difference between them (P=0.00) in the post-radiotherapy ADC (1.53x10-3±0.10×10-3mm2/s vs 1.39×10-3 mm2/s±0.09×10-3 mm2/s). The ADC changes had significant differences (P=0.03) between the good-effect group (95% confidence interval,0.07 x10-3-0.14×10-3 mm2/s) and the poor-effect group (95% confidence interval,-0.07×10-3mm2/s-0.10×10-3mm2/s). In addition, there was no significant difference between the non-cancerous PZs and cancerous PZs in the post-radiotherapy ADC (1.53×10-3±0.11×10-3mm2/s vs 1.50×10"3±0.11×10-3mm2/s, P=0.18).CONCLUSION:The increase of ADC values of PZs after radiotherapy was markedly in prostate cancer patient with better effect. The DWI has potential value for monitoring response to radiation and early predicting the prognosis in patients with prostate cancer.
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