Is There a Role for Functional MRI for the Assessment of Extracapsular Extension in Prostate Cancer?

BACKGROUND/AIM: Exctracapsular extension (ECE) in prostate cancer has a high impact on treatment decision. MRI might predict presence of ECE non-invasively. PATIENTS AND METHODS: Triplanar T2w-sequences, DWI (diffusion weighted imaging) and DCE (dynamic contrast-enhanced imaging) of 34 patients with PCa were analyzed to prior prostatectomy. Sensitivity (SS) and specificity (SP) of T2w, apparent diffusion coefficient (ADC), plasma flow (PF) and mean transit time (MTT) normalized by PCa/normal tissue ratio for prediction of CI (capsular infiltration)/ECE were determined by area-under-the-receiver-operating-characteristics analysis. RESULTS: SS/SP for detecting ECE was 29/85. AUC (area under the curve) of ECE cases was 0.98/0.92/0.69 (cut-off-ratios 3.2/0.51/0.46), SS 93/100/86% and SP 95/80/50% for PF-/MTT-/ADC-ratios, respectively. PF- and MTT-ratios between CI and without CI/ECE differed significantly (PF, p<0.0001; MTT, p=0.0134) with SS/SP 84/89% for PF and SS/SP 52/100% for MTT-ratios. No significant differences regarding ADC-ratios were identified. CONCLUSION: ECE/CI can be assessed by quantitative DCE analysis with great diagnostic confidence and higher specificity than ADC.

Real-time sonoelastography compared to magnetic resonance imaging using four different modalities at 3.0 T in the detection of prostate cancer: strength and weaknesses.

OBJECTIVE: To compare the results of RTE with four different modalities at 3.0 T using endorectal and body phased array coil in the detection of PC. PATIENTS AND METHODS: Between May 2009 and July 2010, 50 patients with biopsy proven PC scheduled for radical prostatectomy (RP) were examined. All patients underwent RTE of the prostate and 3.0 T endorectal MRI. The investigators were unaware of the clinical data and of each others results. RESULTS: RTE detected PC in 46 (92%) and MRI in 42 (84%) of the patients. Depending on the analysis sensitivity was 44.1-58.9% for RTE and 36.7-43.1% for MRI. Specificity was 83.0-74.8% for RTE and 85.9-79.8% for MRI. Sensitivity was significantly higher for RTE (16-sectors: p=0.0348; 8-sectors: p=0.0002) and showed better results in the dorsal (RTE: 51.9%; MRT: 37.7%) and apical to middle (RTE: 66.7%-80.0%; MRI: 41.7%-60.0%) parts of the prostate. MRI showed better results in the base (MRI: 19.4%; RTE: 14.9%) and transitional zone (TZ) (MRI: 34.7%; RTE: 29.6%). Concerning capsular involvement the results were comparable with sensitivity and specificity of RTE being 79.2% and 80.0% compared to 80.8% and 70.0% of MRI. CONCLUSIONS: Concerning sensitivity RTE showed advantages in apical and middle parts whereas MRI may provide advantages in the glands' base and TZ. Both RTE and MRI have limitations particularly in basal and ventral parts. Most of the undetected tumours were of low tumour volume and Gleason Score. Considering capsular involvement both techniques showed comparable results.

Interscanner comparison of dynamic contrast-enhanced MRI in prostate cancer: 1.5 versus 3 T MRI.

PURPOSE: The aim of the study was the comparison of the diagnostic potential of dynamic contrast-enhanced magnetic resonance imaging to differentiate between prostate carcinoma and normal prostate tissue as well as prostatitis at 2 different field strengths: 1.5 versus 3 T. METHODS: Sixty-six patients with biopsy and/or prostatectomy of the prostate were included in the study. Magnetic resonance imaging was performed at 1.5 T in 20 patients with biopsy-proven prostate cancer (PC) and in 8 patients with prostatitis; at 3 T, we analyzed 27 patients with prostatectomy-proven PC and 11 patients with prostatitis. All examinations were performed using a combined body and endorectal coil protocol and a 2-dimensional TurboFLASH T1-weighted gradient echo sequence to calculate plasma flow (PF) and mean transit time (MTT) values. A total of 28 of 38 areas of normal prostate tissue, 20 of 27 areas of PC, and 8 of 11 prostatitis were analyzed at 1.5 or 3T. For the normalization, we calculated PC/normal and prostatitis/normal tissue ratios of PF and MTT for each patient. RESULTS: Prostate cancer showed higher PF (P < 0.0001) and shorter MTT (P < 0.0001) at 3 T and at 1.5 T (P < 0.0001 for PF and P = 0.0016 for MTT) compared with the normal tissue. In comparison with the normal tissue, prostatitis had a statistically significant higher PF at 1.5 T (P = 0.0156) but not at 3 T (P = 0.17) and no significantly shorter MTT values both at 3 (P = 0.15) and 1.5 T (P = 0.25). Sensitivity and specificity for differentiating PC from prostatitis with PF were 46% and 88% at 1.5 T (cutoff ratio, 2.3) and 89% and 73% at 3 T (cutoff ratio, 1.2), respectively. Sensitivity and specificity for MTT were 77% and 100% at 1.5 T (cutoff ratio, 0.7) and 70% and 100% at 3 T (cutoff ratio, 0.6), respectively. We found no significant relationship between the Gleason score and PF/MTT (P = 0.17/0.11 for 1.5 T and P = 0.23/0.18 for 3 T). CONCLUSIONS: The differentiation between PC and the normal tissue is possible with both field strengths. Prostate cancer can be better distinguished from prostatitis at 3 T compared with 1.5 T. The differentiation between prostatitis and the normal tissue is limited at both field strengths.

Ferumoxtran-10 MR lymphography for target definition and follow-up in a patient undergoing image-guided, dose-escalated radiotherapy of lymph nodes upon PSA relapse.

PURPOSE: Evaluation of the lymph node situation in patients with prostate cancer is essential for effective radiotherapy. Using magnet resonance imaging (MRI) of the lymph nodes with ferumoxtran-10 (MR lymphography), it is possible to detect lymph node metastasis. We present our initial experience with ferumoxtran-10 MR lymphography as the basis for image-guided, dose-escalated lymph node radiotherapy and for early follow-up after radiotherapy. PATIENTS AND METHODS: A patient with suspicion for lymph node metastasis after radical prostatectomy was examined with MR lymphography with the lymph node-specific contrast media ferumoxtran-10. Radiotherapy was performed as intensity-modulated radiotherapy with a total dose of 44 Gy to the whole lymphatic drainage, 60 Gy to the area of affected lymph nodes, 71 Gy to the prostate bed, and 75 Gy to the anastomosis region. 8 weeks after completion of radiotherapy, a follow-up MR lymphography with ferumoxtran-10 was performed. RESULTS: In the first MRI with ferumoxtran-10, 5 metastatic lymph nodes were found in the iliac region. The scan 8 weeks postradiotherapy no longer showed lymph nodes suspicious for metastases. PSA (prostate-specific antigen) decreased from 2.06 ng/ml pretherapeutically to 0.02 ng/ml at 2 weeks after treatment and was no longer detectable at 8 months after treatment. CONCLUSIONS: Lymph node staging with ferumoxtran-10 and subsequent dose escalation with intensity-modulated radiotherapy led to the elimination of positive lymph nodes and a decrease in the PSA value.

Value of multiparametric prostate MRI of the peripheral zone.

RATIONALE AND OBJECTIVES: MRI of the prostate offers the possibility to localize and stage prostate cancer and may improve detection of disease. Currently, T2-weighted images and spectroscopy are the most commonly used MRI techniques. To assess the value of prostate MRI and its different modalities in the process of diagnosis, the currently available MRI techniques were compared. MATERIALS AND METHODS: 16 patients were examined on a 1.5 T MR system. All patients underwent the same MR protocol using an endorectal coil: T2-weighted triplanar turbo-spin-echo (TSE), axial echo-planar diffusion-weighted imaging (DWI), 3D chemical-shift imaging MR spectroscopy (MRS) and axial dynamic-contrast-enhanced TurboFLASH (DCE). Parametric maps of the choline+creatine/citrate ratio (CC-CR), apparent diffusion coefficient (ADC) and plasma flow/mean transit time (PF/MTT) were calculated. Additionally, average time for reading and scanning were evaluated. As reference, biopsy results were used. RESULTS: Sensitivity/specificity were 50.0-85.7%/44.4-72.2% for the T2 weighted images, 78.6-100.0%/38.9-55.6% for the ADC maps, 71.4-85.7%/44.4-55.6% for the PF/MTT maps and 64.3-78.6%/50.0-77.8% for the CC-CR. Average scan and reading time were 8:46/1:54 min for T2, 1:28/3:17 min for DWI, 8:41/2:12 min for DCE and 11:36/3:47 for spectroscopy. CONCLUSION: We found no significant differences in accuracy between the modalities. We observed DWI to be advantageous in examination and reading compared to DCE and MRS, therefore it might be the preferred modality when a shortened protocol is needed.