Diffusion Weighted Imaging At 3 Tesla In The Evaluation Of Metastatic Prostate Cancer Aggressiveness

Backgrounds and Objective: Prostate cancer(PCa) is one of the leading causes of cancer-related deaths around the world, and newly diagnosed cases accounts for second among the total number of cancer in men. Numerous studies have confirmed the clinical utility of diffusion weighted imaging(DWI) in numerous cancer imaging. In our recent study, we found that DWI play a major role in muti-parametic MRI, and ADC is a functional parameter in evalution of prostate cancer. The interaction between metastatic features and MRI findings of PCa is unknown. The presence of circulation tumor cells(CTCs) in PCa and its correlation with ADC value has not yet been reported. We also wanted to know whether DWI can be useful to detect the early metastatic PCa. Therefore, the first objective of this study was to investigate the presence of CTCs in PCa and look for its correlation with ADC and tumor grade. We further investigate the clinical utility of DWI in metastatic PCa through CTCs, ADC and PSA. This might bring a new diagnostic foundation and be helpful to guide the therapy strategies of PCa.Materials and Methods: This study was divided into three parts: The first part of study was detecting the presence of CTCs expression in peripheral blood of prostate disease patients and look for a clear correlation with the ADC and Gleason's score. Between 2013 and 2014, we studied a series of 18 prostate disease patients, who underwent CTC evaluation and underwent DWI(b value 0 to 1000s/mm2) at 3.0T on the same day, followed by target biopsy within 48 hrs of MRI.The imaging studies were evaluated independentlyby four observers. Spearman's test was used to analyze correlation between CTC values with ADC value of restricted lesion and Gleason grade. The second part of this study was investigated the ADC of metastatic PCa through DWI and its possible relationships in vivo. Multi b values Single-Shot Echo-Planar Imaging DWI and Readout-Segmented DWI(RS-DWI) were performed to analyze the quality of images. Next, PCa patients were divided into 3 groups: primary cancer, PCa with lymph node metastasis, PCa with bone metastasis.ADC values(b=800,1000s/mm2) were calculated to analyze the relationship of tumors.Comprasion of three groups were evaluated and Pearson test was used to analyze correlation in groups of restricted lesion using ADC values. In third part of this study we included 27 ECT confirmed bone metastatic PCa patients, who underwent whole body diffusion-weighted imaging(WB-DWI). All the patients were followed up for more than 6 months. Four readers(first had 4 years experience in reading prostate imaging,second with 3 years experience in Musculoskeletal imaging, 3rd 5 year residence with PET imaging and fourth reader with more than 5 years experience in prostate pathology imaging) were blinded to the record of the number and location of metastatic lesions. The bones of whole body were divided into four anatomical regions,namely group A(skull),group B( cervical, thoracic and lumbar spine), group C(sternum, collarbone, shoulder blades, rib cages and the double upper limb bone), group D(pelvis, sacrum, coccyx bone and the double lower limbs bone); The Chi-square test was used to detect the difference of the two methods in four regions; Pearson analyses were used to compare the diagnostic consistency between WB-DWI and 18F-FDG PET/CT.Results: In CTCs counting and immunohistochemistry was found: Five patients were diagnosed BPH(5/18) and 13 PCa(12/18). Gleason scores included 4+4=8(n=5), 4+3=7(n=3) and 3+3=6(n=4). The numbers of CTCs in four groups were 44,71,41,22, respectively. Spearman analysis of ADC and the standardized CTCs have a positive correlation(r =0.961, P =0.0386), while pathology finding and the standardized CTCs have high correlation(r=0.931, P=0.0687). Nighty patients with PCawere enrolled in the secondpart. The imaging studies were evaluated independently by two observers and confirmed by a senior observer. MRI findings include metastatic lymph nodes(n=52), bone metastatis(n=36); Clinical data include T3(n=51) and T4(n=39) stage of tumors. Comparasion of ADC values depicted from metastatic bone and tumor was no significant difference(P>0.05), while the metastatic lymph node have significant difference(P<0.05) with PCa. Pearson analysis PCa and suspicious lymph node have a positive correlation(r=0.714, P=0.000) in RS-DWI(b=800s/mm2), the correlation of PCa and metastatic bone tumors was significantly(r=0.47, P=0.036) proved in mutil b DWI(b=1000s/mm2), while there was no significant difference in bone tumors and lymph node.Of twenty-seven patients, index lesions were characterized in 7 patients on WB-MRI and 18F-FDG PET/CT, five were influenced by the distortions in conventional MRI; Total number of lesions in WB-DWI with 18F-FDG PET/CT, 846 and 796 respectively.The Chi-square test shown there was no significant difference in distribution between four groups(?2 =2.438,P = 0.487).There was a significant correlation between WB-DWI and 18F-FDG PET/CT(r = 0.941, P = 0.000), including anatomic GA(r = 0.834, P = 0.079), GB(r = 0.972,P = 0.005), GC(r = 0.99,P = 0.001), GD(r = 0.798,P = 0.105), respectively;Conclusion: This study was first detected CTCs, ADC, Gleason score and correlation in PCa. PCa can promote lower ADC values and high risk tumor promoting CTCs proliferation and metastasis. DWI plays an all-round role in predicting and evaluating the metastasis of PCa.