Diffusion-weighted MRI in prostate cancer detection: evaluation of its performance with pathohistological correlation

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1 Diffusion-weighted MRI in prostate cancer detection: evaluation of its performance with pathohistological correlation Poster No.: C-2155 Congress: ECR 2012 Type: Scientific Exhibit Authors: T. Rieden, A. Revizonskaya, S. Kulikauskas, M. Arefiev, E. Bulanova; Moscow/RU Keywords: DOI: Neoplasia, Surgery, Biopsy, MR, MR-Diffusion/Perfusion, Oncology, Genital / Reproductive system male, Tissue characterisation /ecr2012/C-2155 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 9

2 Purpose Prostate cancer treatment and its prognoses are highly correlated with stage of the disease, so its early detection is crucial [1-5]. The aim of our study was to evaluate the diagnostic performance of pre-biopsy high b-value diffusion-weighted imaging (DWI) and its combined use with T2WI in prostate cancer detection and localization in patients with elevated PSA-levels. We also assessed the added value of fusing T2WI and high b- value DWI images for detection and localization of prostate cancer as they were shown to improve the sensitivity and accuracy of prostate cancer detection [6]. Methods and Materials We prospectively evaluated 56 patients (mean age 67±5,4 years) with elevated serum prostate specific antigen (PSA) levels (4,0>ng/mL), who were referred to MRI studies before prostate biopsy (Fig. 1 on page 2). Standard MRI protocol included 2D T2 weighted images in axial, sagittal and coronal planes, axial STIR for better lymph nodes detection and axial DWI. High b-value DWI (b value = 1000 s/mm²) was performed on 1,5T Toshiba machine with surface coil using half reconstruction algorithm (slice thickness 6/3mm) without breath-holding during the acquisition. Image evaluation consisted of three reading protocols: first standard MRI (T2 WI+STIR) were evaluated, then evaluation was repeated using standard MRI+DWI images and finally T2WI+DWI fusion images were assessed. On fusion images areas of hyperintensity (red-to-yellow color scale) were considered as prostate cancer sites. Apparent diffusion coefficient (ADC) values were calculated in 60 of 68 sites of suspected tumor visible on DWI and T2WI. The ADC values in benign tissues (PZ and TZ of the gland) were also calculated. All the patients underwent 12-core prostate biopsy which was the reference standard. Images for this section: Page 2 of 9

3 Fig. 1: Flowchart of the study design Page 3 of 9

4 Results Mean value of PSA level in 56 patients was 12,8±7,2 ng/ml. In 50 patients (89,3% of patients) 68 sites of suspected cancer were found. 6 patients (10,7% of patients) were diagnosed with benign prostatic hyperplasia (BPH). 33 sites (48,5%) were localized in transition zone (TZ), 23 (33,9%) in peripheral zone (PZ), 12 (17,6%) in both zones. Histologically prostate cancer was proven in 39 of 50 patients (78%) with suspected cancer, mean PSA level 13,8±8,6 ng/ml. The median Gleason score was 6,6. Cancer cells were found in 54 of 68 sites (79,4%): 23 sites (42,6%) were localized in TZ, 19 (35,2%) - in PZ, 12 (22,2%) - in both zones. Table 1 and Fig. 2 on page 5 show the comparison of cancer sites distribution in different zones of prostate gland found on MRI and biopsy studies. Method Total cancer suspected sites MRI Localization of the sites Transition zone Peripheral zone Both zones findings Biopsy findings Table 1. Comparison of cancer sites distribution in different zones of prostate gland found by MRI and biopsy studies. MRI+DWI showed better diagnostic performance that T2WI with some cancer sites not visible on T2WI but clearly distinguished on DWI images and ADC maps (Fig. 3 on page 5 and Fig. 4 on page 6). Among 14 of false-positive sites 10 were localized in transition and 4 in peripheral zone; in all of them histological pattern of BHP was found. Furthermore, in 12 sites of 14 falsepositives (8 - TZ, 4 - PZ) prostatic intraepithelial neoplasia (PIN) was diagnosed (8 of 11 patients with non-proven cancer, mean PSA level 10,5±4,2 ng/ml). In some of them focal area suspicious for neoplastic lesion on ADC map was very small, so it was difficult to measure ADC value correctly because of insufficient ROI square (Fig. 5 on page 7). ADC values were measured in 60 of 68 sites suspected for prostate cancer (88,2%), its mean value was 0,81x10-3 mm²/s (0,42x10-3 mm²/s - 1,2x10-3 mm²/s). For 14 noncancer sites mean ADC value was 1,18x10-3 mm²/s (0,79x10-3 mm²/s - 1,5x10-3 mm²/ Page 4 of 9

5 s). As today PIN is considered a pre-malignant lesion DWI with either separate or fused images showed 100% sensitivity, 75% specificity and 96,4% accuracy. Fusion images didn't significantly improve the performance of standard MRI+DWI, but they were helpful in more precise localization of the cancer sites which were not clearly visible on T2WI alone (Fig. 6 on page 7). Images for this section: Fig. 2: Comparison of cancer sites distribution in different zones of prostate gland found by MRI and biopsy studies. Page 5 of 9

6 Fig. 3: A 60-year-old male with suspected prostate cancer and baseline PSA level 5,37 ng/ml. a. Axial T2-weighted MRI shows a focal hypointense lesion in the left peripheral zone of the prostate gland. b. Axial diffusion-weighted MRI shows a focal hyperintense lesion in the left PZ. c. On the axial ADC map a focal area with a low ADC (0.75x10 ³mm²/ s) was seen in the corresponding site (a,b). d. Histopathological study confirmed a cancer focus in the left PZ - Gleason score 7 (3+4). Page 6 of 9

7 Fig. 4: A 64-year-old male with suspected prostate cancer and baseline PSA level 51 ng/ml. a. Axial T2WI shows heterogeneous TZ of prostate gland without clearly defined tumor. b. Axial diffusion-weighted MRI shows a focal hyperintense lesion in the middle TZ of the prostate gland. c. On the axial ADC map a focal area with a low ADC (0.75x10 ³mm²/s) was seen in the corresponding site (b). d. Histologically proven prostate cancer, Gleason score at biopsy was 5 (2+3). Fig. 5: A 67-year-old male with suspected cancer and baseline PSA level 5.0 ng/ml. a. On axial T2-weighted MRI TZ of prostate gland looks heterogeneous without clearly defined lesion. b. Axial diffusion-weighted MRI shows a focal hyperintense lesion in the left TZ. c. On the axial ADC map a focal hypointense lesion with an ADC value approximately 1.2x10 ³mm²/s was seen at the corresponding site (b). d. Histologically prostatic intraepithelial neoplasia (PIN) was diagnosed. Page 7 of 9

8 Fig. 6: A 85-year-old male with suspected cancer and baseline PSA level 20 ng/ml. a. Axial T2WI shows a focal hypointense lesion in the left TZ of the prostate gland. b. Axial DWI shows a focal hyperintense lesion in the left TZ. c. On the axial ADC map a focal area with a low ADC (0.72x10 ³mm²/s) was seen in the corresponding site (a,b). d. Fusion T2WI+DWI (red-to-yellow scale) image shows successful registration of two images using fusion software and the area of signal change seen on two images (a+b). Page 8 of 9

9 Conclusion Pre-biopsy DWI with high b-value improves diagnostic performance of MRI in prostate cancer detection and localization with higher accuracy in peripheral zone; it can show additional sites to be carefully histologically examined. Fusion T2WI+DWI imaging is helpful for better localization of suspected tumor sites. References 1. Jemal A, Siegel R, Ward E, Hao Y, Xu J, Thun MJ. Cancer statistics, CA Cancer J Clin 2009;59: Schumacher M.C, Burkhard F.C, Thalmann G.N, Fleischmann A, Studer U.E. Good outcome for patients with few lymph node metastases after radical retropubic prostatectomy. Eur Urol 2008, 54: M. Mullerad, H. Hricak, L. Wang et al. Prostate cancer: detection of extracapsular extension by genitourinary and general body radiologists at MR imaging. Radiology Vol. 232, # 1: M. Noguchi, T.A. Stamey, J.E. Neal, C.E. Yemoto. An analysis of 148 consecutive transition zone cancers: clinical and histological characteristics. J. Urol Vol. 163, N.6.: Lim H.K., Kim J.K., Kim K.A., Cho K.S.. Prostate Cancer: Apparent Diffusion Coefficient Map with T2-weighted Images for Detection - A Multireader Study. Radiology 2009; 250: Andrew B. Rosenkrantz, Lorenzo Mabbelli, Xiangtian Kong et al. Prostate Cancer: Utility of Fusion of T2-Weighted and high b-value DWI for peripheral zone tumor detection and localization. J. of MRI : Personal Information Contact information: tatyanarieden@gmail.com Page 9 of 9