Tobias Franiel

Diffusion-weighted Endorectal MR Imaging at 3 T for Prostate Cancer: Tumor Detection and Assessment of Aggressiveness

PURPOSE To assess the incremental value of diffusion-weighted (DW) magnetic resonance (MR) imaging over T2-weighted MR imaging at 3 T for prostate cancer detection and to investigate the use of the apparent diffusion coefficient (ADC) to characterize tumor aggressiveness, with whole-mount step-section pathologic analysis as the reference standard. MATERIALS AND METHODS The Internal Review Board approved this HIPAA-compliant retrospective study and waived informed consent. Fifty-one patients with prostate cancer (median age, 58 years; range, 46-74 years) underwent T2-weighted MR imaging and DW MR imaging (b values: 0 and 700 sec/mm(2) [n = 20] or 0 and 1000 sec/mm(2) [n = 31]) followed by prostatectomy. The prostate was divided into 12 regions; two readers provided a score for each region according to their level of suspicion for the presence of cancer on a five-point scale, first using T2-weighted MR imaging alone and then using T2-weighted MR imaging and the ADC map in conjunction. Areas under the receiver operating characteristic curve (AUCs) were estimated to evaluate performance. Generalized estimating equations were used to test the ADC difference between benign and malignant prostate regions and the association between ADCs and tumor Gleason scores. RESULTS For tumor detection, the AUCs for readers 1 and 2 were 0.79 and 0.76, respectively, for T2-weighted MR imaging and 0.79 and 0.78, respectively, for T2-weighted MR imaging plus the ADC map. Mean ADCs for both cancerous and healthy prostatic regions were lower when DW MR imaging was performed with a b value of 1000 sec/mm(2) rather than 700 sec/mm(2). Regardless of the b value used, there was a significant difference in the mean ADC between malignant and benign prostate regions. A lower mean ADC was significantly associated with a higher tumor Gleason score (mean ADCs of [1.21, 1.10, 0.87, and 0.69] × 10(-3) mm(2)/sec were associated with Gleason score of 3 + 3, 3 + 4, 4 + 3, and 8 or higher, respectively; P = .017). CONCLUSION Combined DW and T2-weighted MR imaging had similar performance to T2-weighted MR imaging alone for tumor detection; however, DW MR imaging provided additional quantitative information that significantly correlated with prostate cancer aggressiveness.

Areas suspicious for prostate cancer: MR-guided biopsy in patients with at least one transrectal US-guided biopsy with a negative finding--multiparametric MR imaging for detection and biopsy planning.

PURPOSE To prospectively investigate the incremental value of multiparametric magnetic resonance (MR) imaging compared with standard T2-weighted imaging for biopsy planning. MATERIALS AND METHODS The study was approved by the institutional review board; informed consent was obtained. Consecutive patients underwent T2-weighted imaging supplemented with multiparametric 1.5-T MR imaging, consisting of hydrogen 1 ((1)H) MR spectroscopy, diffusion-weighted (DW) imaging, and contrast material-enhanced MR imaging. Quantitative parameters were calculated: (choline plus creatine)-to-citrate ratio, apparent diffusion coefficient, and volume transfer constant and exchange rate constant. The prostate was divided into 20 standardized areas. Each area was classified as benign, inconclusive, or suspicious at T2-weighted imaging, followed by quantitative evaluation of all inconclusive and suspicious areas with multiparametric MR imaging. MR-guided biopsy was performed in lesions classified as suspicious for cancer with at least one of the techniques after transfer to three-dimensional T2-weighted images. Diagnostic parameters were calculated on a per-lesion and per-patient basis for all combinations of T2-weighted imaging with multiparametric MR imaging. RESULTS Fifty-four patients had a median of two prior transrectal ultrasonographic biopsies with negative findings. Each patient had a median of three suspicious lesions. Prostate cancer was demonstrated in 21 of 54 patients. Biopsy was performed in 178 lesions; 53 were positive for prostate cancer. Detection rates and test negative results, respectively, were as follows: T2-weighted imaging, 70% and 50%; T2-weighted imaging and (1)H MR spectroscopy, 81% and 32%; T2-weighted imaging and contrast-enhanced MR imaging, 83% and 29%; T2-weighted imaging and DW imaging, 85% and 30%; T2-weighted imaging, (1)H MR spectroscopy, and contrast-enhanced MR imaging, 91% and 13%; T2-weighted imaging, (1)H MR spectroscopy, and DW imaging, 94% and 15%; T2-weighted imaging, DW imaging, and contrast-enhanced MR imaging, 94% and 13%; T2-weighted imaging, (1)H MR spectroscopy, DW imaging, and contrast-enhanced MR imaging, 100% and 0%. CONCLUSION Only the combination of T2-weighted imaging with all three multiparametric techniques depicts all identifiable prostate cancers; a double combination with DW imaging and (1)H MR spectroscopy or contrast-enhanced MR imaging misses 6%, while reasonably reducing the number of areas needing biopsy.

PI-RADS-Klassifikation: Strukturiertes Befundungsschema für die MRT der Prostata

PURPOSE To flesh out the ESUR guidelines for the standardized interpretation of multiparametric magnetic resonance imaging (mMRI) for the detection of prostate cancer and to present a graphic reporting scheme for improved communication of findings to urologists. MATERIALS AND METHODS The ESUR has recently published a structured reporting system for mMRI of the prostate (PI-RADS). This system involves the use of 5-point Likert scales for grading the findings obtained with different MRI techniques. The mMRI includes T2-weighted MRI, diffusion-weighted imaging, dynamic contrast-enhanced MRI, and MR spectroscopy. In a first step, the fundamentals of technical implementation were determined by consensus, taking into account in particular the German-speaking community. Then, representative images were selected by consensus on the basis of examinations of the three institutions. In addition, scoring intervals for an aggregated PI-RADS score were determined in consensus. RESULTS The multiparametric methods were discussed critically with regard to implementation and the current status. Criteria used for grading mMRI findings with the PI-RADS classification were concretized by succinct examples. Using the consensus table for aggregated scoring in a clinical setting, a diagnosis of suspected prostate cancer should be made if the PI-RADS score is 4 or higher (≥ 10 points if 3 techniques are used or ≥ 13 points if 4 techniques are used). Finally, a graphic scheme was developed for communicating mMRI prostate findings. CONCLUSION Structured reporting according to the ESUR guidelines contributes to quality assurance by standardizing prostate mMRI, and it facilities the communication of findings to urologists.

Evaluation of normal prostate tissue, chronic prostatitis, and prostate cancer by quantitative perfusion analysis using a dynamic contrast-enhanced inversion-prepared dual-contrast gradient echo sequence.

Objective:To quantify independent pharmacokinetic parameters for differentiation of prostate pathology. Material and Methods:Twenty-seven patients with biopsy-proven prostate cancer (PSA: 1.4–16.1 ng/mL) underwent magnetic resonance imaging with a new dynamic contrast-enhanced, inversion-prepared dual-contrast gradient echo sequence (T1/T2*-weighted, 1.65 seconds temporal resolution) using a combined endorectal/body phased-array coil at 1.5 Tesla. Perfusion, blood volume, mean transit time, delay, and dispersion were calculated using a sequential 3-compartment model. Twenty-three patients underwent prostatectomy. For histologic correlation a pathologist mapped areas of normal prostate tissue, chronic prostatitis, and prostate cancer (total of 63 areas) on histologic sections corresponding to the magnetic resonance imaging planes. Results:Compared with normal prostate tissue, low-grade cancer (Gleason score ≤6) only showed higher perfusion (1.01 mL/cm3/min vs. 0.26 mL/cm3/min, P = 0.050), whereas high-grade cancer showed higher perfusion (1.21 mL/cm3/min vs. 0.26 mL/cm3/min, P ≤ 0.001), higher blood volume (1.44% vs. 0.95%, P = 0.005), shorter mean transit time (3.55 seconds vs. 4.40 seconds, P = 0.019), shorter delay (10.15 seconds vs. 13.36 seconds, P = 0.015), and smaller dispersion (8.56 seconds vs. 12.11 seconds, P = 0.020). High-grade cancer showed higher perfusion than chronic prostatitis (1.21 mL/cm3/min vs. 0.90 mL/cm3/min, P = 0.041). Chronic prostatitis showed higher perfusion (0.90 mL/cm3/min vs. 0.26 mL/cm3/min, P = 0.006), higher blood volume (1.53% vs. 0.95%, P = 0.046), shorter delay (11.42 seconds vs. 13.36 seconds, P = 0.015), and smaller dispersion (10.49 seconds vs. 12.11 seconds, P = 0.020) than normal prostate tissue. There were no statistically significant differences between low-grade and high-grade cancer or between low-grade cancer and chronic prostatitis. Conclusion:The pharmacokinetic parameters investigated, especially perfusion, allow statistically significant in situ differentiation of normal prostate tissue from cancer and chronic prostatitis and of high-grade cancer from chronic prostatitis.

Assessment of PI-RADS v2 for the Detection of Prostate Cancer

PURPOSE To evaluate the diagnostic performance and inter-reader reliability of the multiparametric magnetic resonance imaging (mpMRI) based prostate imaging reporting and data system (PI-RADS) version 1 and version 2 for the assessment of prostate cancer. MATERIAL AND METHODS A cohort of 82 patients underwent endorectal mpMRI at 1.5T. Patients had at least one lesion with a PI-RADS v1 assessment category of ≥3 and were selected for targeted in-bore MR-guided biopsy in a subsequent session. The results of the histopathological workup were used as reference standard. All lesions were retrospectively evaluated according to PI-RADS v2 by an experienced and unexperienced blinded reader. Diagnostic performance was compared by analyzing the area under the Receiver Operating Characteristics Curve (AUC). The weighted kappa method was used to calculate inter-reader reliability. RESULTS Targeted MR-guided biopsy was performed in 136 lesions and revealed 39 malignant lesions in 31 patients. AUC values increased for the experienced reader (PI-RADS v1 0.79; PI-RADS v2 0.83) and unexperienced reader (PI-RADS v1 0.70; PI-RADS v2 0.83). When excluding the cases of low grade cancer (Gleason score=3+3), AUC values increased further for the experienced reader (PI-RADS v1 0.88; PI-RADS v2 0.91) and unexperienced reader (PI-RADS v1 0.78; PI-RADS v2 0.90). Specificity at the selected threshold of a PI-RADS v1/v2 assessment category ≥4 improved for both readers. Inter-reader agreement increased from κ=0.55 in PI-RADS v1 to κ=0.68 in v2. CONCLUSION PI-RADS v2 improved diagnostic performance for the assessment of suspicious intraprostatic lesions identified in PI-RADS v1 for both readers and led to higher inter-reader reliability. These results suggest that PI-RADS v2 is a reliable and replicable reporting system for the assessment of prostate cancer.

Evaluation of the prostate imaging reporting and data system for the detection of prostate cancer by the results of targeted biopsy of the prostate.

PurposeThe purpose of this study was to evaluate the magnetic resonance prostate imaging reporting and data system (PI-RADS) for the detection of prostate cancer by the results of magnetic resonance imaging (MRI)–guided biopsy of the prostate as a reference standard. Patients and MethodsIn 55 patients who had undergone MRI-guided biopsy of the prostate, we retrospectively matched every biopsy core with the corresponding lesion in previously acquired endorectal multiparametric MRI including T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced MRI (DCE-MRI) at 1.5 T. Two readers blinded to the results of the biopsy evaluated each biopsied lesion according to the PI-RADS scoring system. The results of the targeted biopsy were used as a reference standard. Receiver operating characteristic analysis was performed for statistical analysis. ResultsA total of 113 lesions in the 55 patients were evaluated; 30 lesions were malignant. When evaluated according to the criteria of the PI-RADS scoring system, DCE-MRI revealed a lower area under the receiver operating characteristic curve (AUC) (0.76) compared with T2WI (0.88; P = 0.06) and DWI (0.93; P = 0.004). A sum score combining T2WI, DWI, and DCE-MRI yielded an AUC of 0.93, whereas a sum score combining only T2WI and DWI yielded an AUC of 0.95. In central gland lesions, T2WI showed a numerically higher AUC compared with DWI (0.98 and 0.95), whereas, in peripheral zone lesions, DWI was superior (AUC of 0.93 and 0.73; P = 0.04). An approach assigning a PI-RADS score for T2WI to central gland lesions and for DWI to peripheral zone lesions yielded an AUC of 0.96 and was numerically superior compared with any sequence alone and sum scores combining T2WI and DWI as well as T2WI, DWI, and DCE-MRI. ConclusionsThe PI-RADS scoring system shows a good diagnostic performance for the detection of prostate cancer when using a sum score. However, DCE-MRI does not seem to add significant value when evaluated according to the recommended criteria. Assigning a score for T2WI to central gland lesions and for DWI to peripheral zone lesions might be sufficient for stratification of patients for further diagnostic workup.

Prostate MR Imaging: Tissue Characterization with Pharmacokinetic Volume and Blood Flow Parameters and Correlation with Histologic Parameters

PURPOSE To prospectively determine whether pharmacokinetic magnetic resonance (MR) imaging parameters correlate with histologic mean vessel density (MVD), mean vessel area (MVA), and mean interstitial area (MIA) and whether these parameters enable differentiation of prostate cancer, chronic prostatitis, and normal prostate tissue. MATERIALS AND METHODS This study was approved by the institutional review board, and informed consent was obtained from all patients. Thirty-five patients with biopsy-proved prostate cancer were examined with a dynamic contrast material-enhanced inversion-prepared dual-contrast gradient-echo sequence (temporal resolution, 1.65 seconds) at 1.5 T to calculate blood volume, interstitial volume, and blood flow. These parameters were correlated with MVD, MVA, and MIA in 95 areas (prostate cancer, n = 36; chronic prostatitis, n = 27; normal prostate tissue, n = 32). For each MR area, five 1-mm(2) squares (original magnification, x100) of the matching histologic area were analyzed. The Wilcoxon signed-rank test was used for statistical analysis. RESULTS Blood volume correlated poorly with MVD (Spearman correlation coefficient, 0.252; P = .014) but did not correlate at all with MVA (P = .759). Interstitial volume did not correlate with MIA (P = .507). Blood volume differed between patients with prostate cancer and those with a normal prostate (1.49% vs 0.84%, respectively; P < .001). Interstitial volume differed between patients with chronic prostatitis and those with a normal prostate (39.00% vs 22.59%, respectively; P = .022). Blood flow differed between patients with prostate cancer and those with a normal prostate (0.97 mL/[cm(3) x min(-1)] vs 0.34 mL/[cm(3) x min(-1)], respectively; P < .001), between patients with prostate cancer and those with chronic prostatitis (0.97 mL/[cm(3) x min(-1)] vs 0.60 mL/[cm(3) x min(-1)], respectively; P = .026), and between patients with chronic prostatitis and those with a normal prostate (0.60 mL/[cm(3) x min(-1)] vs 0.34 mL/[cm(3) x min(-1)], respectively; P = .023). CONCLUSION Blood volume and interstitial volume did not reliably correlate with the histologic parameters. Only blood flow enabled differentiation of prostate cancer, chronic prostatitis, and normal prostate tissue.

MRI before and after external beam intensity-modulated radiotherapy of patients with prostate cancer: The feasibility of monitoring of radiation-induced tissue changes using a dynamic contrast-enhanced inversion-prepared dual-contrast gradient echo sequence

PURPOSE To identify and quantify suitable pharmacokinetic MRI parameters for monitoring tissue changes after external beam intensity-modulated radiotherapy of prostate cancer. MATERIAL AND METHODS Six patients with biopsy-proven prostate cancer (initial PSA, 6.0-81.4 ng/ml) underwent MRI at 1.5 T using a combined endorectal/body phased-array coil and a dynamic contrast-enhanced inversion-prepared dual-contrast gradient echo sequence (T1/T2(*)w; 1.65 s temporal resolution). MRI was performed before and immediately after radiotherapy, at 3 months and at 1 year. Perfusion, blood volume, mean transit time, delay, dispersion, interstitial volume, and extraction coefficient were calculated in prostate cancer and normal prostate for all four time points using a sequential 3-compartment model. RESULTS Prostate cancer and normal prostate tissue showed a statistically significant decrease in perfusion (p=0.006, p=0.001) and increase in extraction coefficient (p=0.004, p<0.001). For prostate cancer, there was also a decrease in vascular volume (p=0.034). The other parameters investigated showed no statistically significant changes. Statistically significant differences between prostate cancer and normal prostate tissue were only observed before radiotherapy, when prostate cancer showed significantly higher perfusion (1.84 vs. 0.12 ml/cm(3)min, p=0.028) and a smaller extraction coefficient (0.42 vs. 0.64, p=0.028). CONCLUSIONS Two pharmacokinetic parameters, perfusion and extraction coefficient, appear to be suitable candidates for monitoring the response to percutaneous intensity-modulated radiotherapy of prostate cancer.

Effect of butylscopolamine on image quality in MRI of the prostate

AIM To evaluate the impact of butylscopolamine on the quality of magnetic resonance imaging (MRI) images of the prostate. MATERIAL AND METHODS Eighty-two MRI examinations of the prostate were retrospectively analysed. MRI was performed with a combined endorectal/body phased-array coil including proton density-weighted (PD) sequence, T1-weighted turbo spin-echo (TSE)-sequence, and T2-weighted TSE-sequences. Forty milligrams of butylscopolamine was administered intramuscularly in 31 patients (im-group) and intravenously in 30 patients (iv-group). Twenty-one patients did not receive premedication with butylscopolamine (ø-group). Overall image quality, delineation of the bowel wall, and visualization of the prostate, neurovascular bundle, and pelvic lymph nodes were evaluated qualitatively using a five-point scale (from 1=excellent to 5=non-diagnostic/structure not discernible). Motion artefacts within the endorectal coil were quantified by baseline adjusted signal intensities inside the endorectal coil area. RESULTS Delineation of the bowel wall using the PD-sequence was significantly improved after both intramuscular and intravenous butylscopolamine administration (ø-group: 3.6+/-0.7; im-group: 2.9+/-0.7; iv-group: 2.9+/-0.7; p=0.001). However, there were no significant differences in motion artefacts measured within the endorectal coil (ø-group: 1.18+/-0.14; im-group: 1.15+/-0.11; iv-group: 1.12+/-0.06; p=0.39). There were also no significant differences in qualitative assessment of visualization of the prostate, neurovascular bundle, pelvic lymph nodes, and of overall image quality between the study groups. CONCLUSION : In conclusion, butylscopolamine had only a small effect on image quality and is not mandatory for MRI of the prostate.

The value of ADC, T2 signal intensity, and a combination of both parameters to assess Gleason score and primary Gleason grades in patients with known prostate cancer

Background The ability to non-invasively analyze tumor aggressiveness is an important predictor for individual treatment stratification and patient outcome in prostate cancer (PCA). Purpose To evaluate: (i) whether apparent diffusion coefficient (ADC), the T2 signal intensity (SI), and a combination of both parameters allow for an improved discrimination of Gleason Score (GS) ≥7 (intermediate and high risk) and GS <7 (low risk) in PCA; and (ii) whether ADC may distinguish between 3 + 4 and 4 + 3 PCA (primary Gleason grades [pGG]). Material and Methods Prostatectomy specimens of 66 patients (mean age, 63 ± 5.6 years; 104 PCA foci) with a preceding multiparametric 1.5 T endorectal coil magnetic resonance imaging (MRI) were included. ADC (b values = 0, 100, 400, 800 s/mm2), standardized T2 (T2s), and the ADC/T2s ratio were tested for correlation with GS applying multivariate analysis. ADC cutoff values were calculated for prediction of GS and pGG, and logarithm of the odds (LOGIT) was used to express the probability for GS and pGG. Diagnostic accuracy was assessed by ROC analysis. Results We found an almost linear negative relationship of ADC for GS ≥7 (P = 0.002). The effect of ADC for GS ≥7 (adjusted odds ratio = 0.995) was almost identical for peripheral and transition zone PCA (P = 0.013 and P < 0.001, respectively). ADC showed an AUC of 78.9% for discrimination between GS <7 and GS ≥7. An ADC cutoff of <1.005 × 10−3 mm2/s indicated a GS ≥7 (90.5% sensitivity, 62.5% specificity). Within the group of GS = 7 PCA, an ADC > 0.762 × 10−3 mm2/s indicated a pGG of 3 (AUC = 69.6%). Conclusion T2s and the ADC/T2s ratio do not provide additional information regarding prediction of GS. ADC values have a good discriminatory power to distinguish tumors with GS ≥7 from GS <7 and to predict pGG in GS = 7 PCA.