The Value Of Diffusion Weighted Imaging At3.0T Mr In The Diagnosis Of Prostate Cancer And The Exploration In New Technique

Part I:Prostate Cancer:Comparison of Tumor Visibility and Diagnostic Efficacy on T2WI, Diffusion-Weighted Images and the Apparent Diffusion Coefficient Map and the relationship between the ADC and gleason scoreObjective:The purpose of our study was to compare the visibility and diagnostic efficacy of prostate cancer on T2WI, diffusion-weighted imaging(DWI) and the apparent diffusion coefficient (ADC) map, and investigate the relationship between the ADC and Gleason score.Materials and methods:In this retrospective study,115patients (70patients with prostate cancer and45with benign lesions) underwent preoperative MRI, including DWI(b values0,1,000s/mm2). Two observers reviewed the images with reference to a10-core biopsy. The visibility of cancer on T2WI, DWI and ADC map were compared on a per-site of biopsy basis and a per-patient basis, and the relationship between visibility and gleason score were also investigated. The ADC value of the visible cancer foci and the normal tissue were measured and compared, and the relationship between the ADC value and Gleason score were assessed. The T2WI, DWI images and ADC maps were also compared in terms of the sensitivity and specificity in identification of prostate cancer on the per-site of biopsy and a per-patient basis.Results:For276positive site of biopsy in70patients, the percentage of visible cancer on T2WI (85.1%) was higher than DWI (62.3%) and ADC map (69.1%)(all p<0.05). The percentage of visible cancer with lower Gleason score (3+3,3+4) was lower than the cancer with higher score (all p<0.05). But on a per-patient basis, The percentage of visible cancer were all relatively higher (87.1%,84.2%,84.2%) on T2WI, DWI and ADC map, and no significant differences were found among them. The ADC value of prostate cancer(0.86±0.11×10-3mm2/s)was significantly lower than normal peripheral zone(PZ)(1.73±0.31×10-3mm2/s) and central gland (CG)(1.35±0.16×10-3mm2/s)(P<0.05), and an inverse relationship between the ADC and the Gleason score were abserved (P<0.05). On a per-site basis, the sensitivity of T2WI in detection of prostate were highest (69.2%)(DWI60.7%, ADC63.4%), but the specificity (69.8%)and accuracy (68.1%)were significantly lower than DWI (92.7%,79.6%) and ADC map (94.6%,82.3%)(P<0.05), while the positive predictive value (PPV) and negative predictive value(NPV) were similar among the three methods. However, on a per-patient basis, the sensitivity, specificity, PPV, NPV and accuracy of T2WI (74.3%,66.7%,77.6%,66.7%,71.3%) were significantly lower than DWI (82.9%,86.6%,90.6%,76.4,84.3%) and ADC map (84.3%,91.1%,93.6%,78.8%,87.0%)Conclusion:Given a remarkable proportion of tumors invisible on the ADC map and DWI images, the diagnosis of prostate with DWI/ADC only may miss some lesions and underestimated the volume of tumor. However, the ADC value and DWI images feature of cancer were significantly different from the normal tissue, and a relatively higher specificity, specificity were obtained on a per-patient basis, suggesting that it may play a greater role in the screening and differentiating of caner from benign lesions. The inverse relationship between the tumor ADC value and the Gleason score may also contribute to the assessment of the aggressiveness of prostate cancer. Part II:The Value of Diffusion Weighted Imaging in the Diagnosis of Prostate Organ-confined Cancer:Compared with Dynamic Contrast Enhanced MRIObjective:To assess the value of diffusion weighted imaging (DWI)image, signal and ADC value in the diagnosis of prostate organ-confined cancer on3.0T MRI, and compared to Dynamic Contrast Enhanced MRI(DCE-MRI)Materials and methods:The T2WI,DCE-MRI,DWI images and ADC maps of38patients with prostate organ-confined caner in peripheral zone(PZ) and25in central gland (CG),25patients with prostatitis,21with BPH were analyzed, the ADC value, signal to noise ratio(SNR) of lesions were measured, and a semi-quantitative score of the lesion base on the feature of DWI image were performed. The Signal-time (S-T) curve and time to peak enhancement(TTP) were also obtained. The prostate cancer and benign lesions were compared in term of ADC value, SNR, DWI score, S-T curve and TTP, and the diagnostic efficacy of the above method and the combination of them were evaluated.Results:33prostate cancer in PZ and29in CG,34chronic prostatitis and35BPH lesion were included. The ADC value of prostatitis(1.27±0.18×10-3mm2/s) was higher than PZ cancer (0.92±0.14×10-3mm2/s), and the value of BPH(1.07±0.16×10-3mm2/s) was higher than CG cancer (0.84±0.12×10-3mm2/s)(p<0.05), while the SNR of prostatitis(23.6±6.1) was significantly lower than PZ cancer (29.4±7.4),BPH(26.6±4.1) were lower than CG cancer (30±6.5)(p<0.05)。The specificity, specificity for ADC value to differentiate PZ cancer from prostatitis were90.1%and85.3%,the AUC (area under ROC curve)was0.95,which was significantly higher than DCE-MRI,DWI semi-quantitative score and SNR (0.80,0.79,0.72)(p<0.05)。The sensitivity, specificity for ADC value to distinguish CG cancer from BPH were 82.8%and74.3%,the AUC (0.8) was significantly higher than DWI semi-quantitative score and SNR (0.64,0.62)(p<0.05).The AUC of DCE-MRI (0.75) was lower than ADC but did not reach a significant difference (p>0.05). The combination of these method could further improve the diagnostic efficacy(sensitivity97.0%, specificity85.3%in PZ lesions with AUC of0.97, CG sensitivity93.1%, specificity74.3%in CG lesions with AUC of0.82), the AUCs were both significantly higher than DCE-MRI, DWI semi-quantitative score and SNR (p<0.05)。Conclusion:ADC value on3.0T MRI yielded a relatively higher accuracy in the differentiation of prostate organ-confined caner and benign lesions. The diagnostic efficacy of ADC value was significantly higher than DCE-MRI, DWI semi-quantitative score and SNR in differentiating PZ caner from prostatisis, and higher than DWI semi-quantitative score and SNR in differentiating CG caner from BPH. Therefore, the ADC value could serve as a major index of the diagnosis, meanwhile, the combination of the DCE-MRI, DWI and ADC value and produce a higher accuracy than separate use of these methods Part III:Multi-b Value Biexponential Diffusion Weighted Imaging of Normal Prostate Tissue, Prostate Cancer and Benign Lesions:Compared with Monoexponential Diffusion Weighted ImagingObjective:To obtain biexponential apparent diffusion parameters of different prostate tissue and compare with monoexponential apparent diffusion coefficient (ADC) in differentiating prostate cancer from benign lesionsMaterial and Methods:Eleven healthy volunteers and35patients with pathologically confirmed prostate cancer,27with benign prostatic hyperplasia (BPH) and25with prostatitis underwent diffusion-weighted imaging with10b-factors from0to3000s/mm2.underwent a conventional (b-factors0,1000s/mm2) and a10b-factors (0to3000s/mm2) diffusion-weighted imaging (DWI). The monoexponential ADC value and biexponential parameters fast ADC (ADCf), fraction of ADCf (f), slow ADC (ADCs) value for prostate cancer, BPH, prostatitis and normal tissue were calculated and compared. Receiver operating characteristic (ROC) analysis was performed for those parameters.Results:Biexponential and monoexponential parameters were obtained for42prostate cancer,34BPH,32prostatitis and98normal PZ tissue and93normal CG tissue.The ADC value of normal PZ tissue(1.69±0.28×10-3mm2/s) was significantly higher than CG (1.36±0.12×10-3mm2/s)(p<0.01), and prostate cancer tissue had remarkablely lower ADC(0.84±0.12×10-3mm2/s) than the other tissue, while the ADC value of prostatitis (1.42±0.23×10-3mm2/s)was lower than PZ (p<0.01),and BPH (1.22±0.22×10-3mm2/s)lower than CG (p<0.01).The f and ADCs (×10-3mm2/s) were higher in PZ than CG (68.7±9.8%Vs54.2±6.1%, and1.51±0.36vs.0.82±0.21, both P<0.01), but no significant difference was observed in the ADCf (×10-3mm2/s)(3.80±0.43vs.3.77±0.64, P>0,01). Prostate cancer tissue had lower ADC(0.84±0.12×10-3mm2/s), ADCf (3.80±0.43×10-3mm2/s, f, and ADCs than the other tissues (all p<0.01).Prostatitis tissue exhibited a lower ADCf (3.06±0.49×10-3mm2/s), ADCs (0.91±0.29×10-3mm2/s) and smallerf (59.8±9.2%) than peripheral zone (p<0.01). BPH showed a lower ADCf (3.29±0.62×10-3mm2/s) than central gland(p<0.01), but no difference in f and ADCs (p>0.01).The ADCf demonstrated comparable accuracy with ADC in differentiating cancer from BPH[area under the curve (AUC)0.91Vs0.86], the sensitivity and specificity were88.3%and72.6%,88.2%and77.3%, respectively. The AUC of ADCf and ADC were similar in differentiating cancer and prostatitis (0.96Vs0.94)(both p>0.05), with the the sensitivity and specificity93.5%and89.3%,90.3%and93.2%, respectively, but the AUC of f and ADCs in differentiating cancer from BPH (0.73and0.76) and prostatitis (0.87and0.82) were significantly lower than ADC (all p<0.05). The sensitivity and specificity of the combination of all the biexponential parameterswere higher than the separate use of these parameters, both in the differentiating cancer from BPH(93.2%and81.8%) and (100%,88.7%)Conclusion:The biexponential DWI provided additional tissue characterization parameters for different prostate tissue and ADCf yielded comparable accuracy with ADC in identification of prostate cancer. The ADCf yielded comparable accuracy with ADC in identification of prostate cancer, and the combination of the biexponential parameter could further improve the diagnostic efficacy. Part Ⅳ:Differentiation of Central Gland Cancer from Benign Prostatic Hyperplasia by Using the Monoexponetial and Biexponential Diffusion Weighted ImagingObjective:To analyze and commpared the monoexponetial and biexponential diffusion weighted imaging (DWI) parameters of prostate cancer, stromal hyperplasia (SH), and glandular hyperplasia (GH) and to determine the role of these parameters in differentiation of central zone (CG) cancer from benign hyperplasia.Materials and Methods:nineteen patients with cancer in CG,20with cancer in PZ and BPH simultaneitily, underwent preoperative monoexponetial, biexponential Echo Planar Imaging (EPI) DWI. The monoexponetial DWI was performed with two b values of0,1000s/mm2, and the biexponential DWI with ten b value from0to3000s/mm2. All the cancer and hyperplastic foci on MR images were localized on the basis of histopathologic correlation. Data of21SH nodules,26GH nodules(obtained from the CG of PZ cancer patients, and23foci of cancer in CG were analyzed, the apparent diffusion coefficient (ADC)of the monoexponetial DWI, the fast apparent diffusion coefficient (ADCf), slow apparent diffusion coefficient (ADCs)value and the fraction of ADCf(f) of biexponential DWI for all the lesions were calculated. Receiver operating characteristic (ROC) analysis was performed for differentiation of CG cancer from SH and GH foci.Result:The ADC differed significantly in the three tissue, the ADC value of SH (1.06±0.15×10-3mm2/s) was significantly higher than cancer(p<0.05)but lower than GH(p<0.02).The areas under the ROC curve (AUCs) of ADC were1.00and0.80, respectively, for differentiation of carcinoma from GH and SH. A cuttoff of1.0offer a sensitivity of73.7%.specificity of84.21%for CA and SH,100%and90%for cancer and GH. However,a remarkable overlap was observed between the ADC value of SH and cancer. The ADCf of cancer (1.99±0.35×10-3mm2/s) was significantly lower than the GH and SH (3.11±0.30×10-3mm2/s)(p<0.02), but no significant difference was found between the GH and SH. The ADCfyielding a comparable AUCs(1.00, p>0.05) with ADC for differentiation of cancer from GH and a higher AUCs (0.92)compared with ADC(p<0.05) for differentiation of cancer from SH. A cuttoff of2.5offer a sensitivity of84.21%, specificity of90.00%for CA and SH,100%and90%for Cancer and GH.ADCs (1.12±0.21×10-3mm2/s) and f (61.1%±8.7%) were significantly higher in GH than cancer (0.53%±0.17,47.7%±6.1%)(p<0.02), revealed AUCs of0.97and0.90in differentiation of cancer from GH, and the sensitivity and specificity of for CA and GH were85%and85%,85%and100%respectively, the ADCs of SH (0.79±0.21×10-3mm2/s) was significantly higher than cancer(p<0.02) but the f (47.7±6.1%) were close to cancer(p>0.02), offering a relatively lower AUCs (0.56and0.68) in differentiation of cancer from SH, and the sensitivity and specificity of for CA and SH were65%and56.4%,68.4%and60%,respectively.Conclusion:Both the monoexpontial and biexponetial DWI could potentially improve the detection and differentiation of prostate cancer in CG, and the ADCf in the biexponetial model offered a better accuracy to differentiate cancer from SH compared with the ADC.