[en] Highlights: • The prostate-specific antigen density (PSAD) was calculated for the TZ (TZPSAD). • TZPSAD may be a better surrogate marker for cancer aggressiveness than PSAD. • A TZPSAD threshold of 0.22 ng/ml² may help in risk stratification. - Abstract: Purpose: To compare the correlation of transition zone prostate-specific antigen density (TZPSAD) versus whole gland (WG) density (PSAD) with Gleason score.

[en] To assess interreader agreement of manual prostate cancer lesion segmentation on multiparametric MR images (mpMRI). The secondary aim was to compare tumor volume estimates between MRI segmentation and transperineal template saturation core needle biopsy (TTSB). We retrospectively reviewed patients who had undergone mpMRI of the prostate at our institution and who had received TTSB within 190 days of the examination. Seventy-eight cancer lesions with Gleason score of at least 3 + 4 = 7 were manually segmented in T2-weighted images by 3 radiologists and 1 medical student. Twenty lesions were also segmented in apparent diffusion coefficient (ADC) and dynamic contrast enhanced (DCE) series. First, 20 volumetric similarity scores were computed to quantify interreader agreement. Second, manually segmented cancer lesion volumes were compared with TTSB-derived estimates by Bland-Altman analysis and Wilcoxon testing. Interreader agreement across all readers was only moderate with mean T2 Dice score of 0.57 (95%CI 0.39–0.70), volumetric similarity coefficient of 0.74 (0.48–0.89), and Hausdorff distance of 5.23 mm (3.17–9.32 mm). Discrepancy of volume estimate between MRI and TTSB was increasing with tumor size. Discrepancy was significantly different between tumors with a Gleason score 3 + 4 vs. higher grade tumors (0.66 ml vs. 0.78 ml; p = 0.007). There were no significant differences between T2, ADC, and DCE segmentations. We found at best moderate interreader agreement of manual prostate cancer segmentation in mpMRI. Additionally, our study suggests a systematic discrepancy between the tumor volume estimate by MRI segmentation and TTSB core length, especially for large and high-grade tumors.

[en] 

Purpose

The purpose of our study was to retrospectively evaluate and categorize temporal changes in MRI appearances of the prostate in patients who underwent focal therapy with MRI follow-up.

Methods

The Institutional Review Board approved this retrospective study and waived the requirement for informed consent. Thirty-seven patients (median age 61; 48–70 years) with low-to-intermediate-risk, clinically organ-confined prostate cancer underwent focal ablation therapy from 2009 to 2014. Two radiologists reviewed post-treatment MRIs (n = 76) and categorized imaging features blinded to the time interval between the focal therapy and the follow-up MRI. Inter-reader agreement was assessed (kappa) and generalized linear regression was used to examine associations between an imaging feature being present/absent and days between ablation and MRI.

Results

Inter-reader agreement on MRI features ranged from fair to substantial. Edema was found present at earlier times after ablation (median 16–25 days compared to MRIs without edema, median 252–514 days), as was rim enhancement of the ablation zone (18–22.5 days vs. 409–593 days), a hypointense rim around the ablation zone on T2-weighted images (53-57.5 days vs. 279–409 days) and the presence of an appreciable ablation cavity (48.5–60 days vs. 613–798 days, all p < 0.05). Enhancement of the ablation zone/scar (553–731 days vs. 61.5–162 days) and the formation of a T2-hypointense scar were found to be present on later MRI scans (514–553 days vs. 29–32 days, one reader).

Conclusions

The MRI appearance of the prostate after focal ablation changes substantially over time. Identification of temporal patterns in the appearance of imaging features should help reduce image interpretation variability and errors when assessing post-therapeutic scans.

[en] To investigate the effects of androgen-deprivation therapy (ADT) on MRI parameters and evaluate their associations with treatment response measures. The study included 30 men with histopathologically confirmed prostate cancer who underwent MRI before and after initiation of ADT. Thirty-four tumours were volumetrically assessed on DW-MRI (n = 32) and DCE-MRI (n = 18), along with regions of interest in benign prostatic tissue, to calculate apparent diffusion coefficient (ADC) and transfer constant (K^trans) values. Changes in MRI parameters and correlations with clinical parameters (change in prostate-specific antigen [PSA], treatment duration, PSA nadir) were assessed. Prostate volume and PSA values decreased significantly with therapy (p < 0.001). ADC values increased significantly in tumours and decreased in benign prostatic tissue (p < 0.05). Relative changes in ADC and absolute post-therapeutic ADC values differed significantly between tumour and benign tissue (p < 0.001). K^trans decreased significantly only in tumours (p < 0.001); relative K^trans changes and post-therapeutic values were not significantly different between tumour and benign tissue. The relative change in tumour ADC correlated significantly with PSA decrease. No changes were associated with treatment duration or PSA nadir. Multi-parametric MRI shows significant measurable changes in tumour and benign prostate caused by ADT and may help in monitoring treatment response. (orig.)

[en] Highlights: • Prostate MRIs from different institutions of 80 patients were manually, voxel-wise segmented. • Six readers (2 trainees, 2 radiologists, 2 researchers) performed the segmentations. • Variability was highest in the apex, lower in the base, and lowest in the midgland. - Abstract: Purpose: To evaluate the interreader variability in prostate and seminal vesicle (SV) segmentation on T2w MRI.

[en] 

Purpose

To assess the value of diffusion-weighted MRI in the pre-therapeutic evaluation of pediatric renal cortical tumors.

Methods

This IRB-approved, retrospective multi-center study included 122 pediatric patients with 130 renal tumors, who underwent MRI including DWI before neoadjuvant chemotherapy and nephrectomy. Two radiologists independently assessed each tumor volumetrically, and apparent diffusion coefficient (ADC) values were calculated on a voxel-wise basis, including parameters derived from histogram and texture analysis.

Results

Inter-reader agreement was excellent (ICC 0.717–0.975). For both readers, patients with locally aggressive tumor growth (SIOP 3 stage) or with metastases (M1) had significantly lower 12.5th-percentile ADC values (p ≤ 0.028) compared to those with lower-stage tumors, and the parameter energy differed significantly between patients with M1 and those with M0 status (p ≤ 0.028). Contrast and homogeneity differed significantly between benign nephroblastomatosis and malignant nephroblastoma (p ≤ 0.045, both readers). As compared to all other subtypes, the blastemal subtype demonstrated significantly higher skewness (p ≤ 0.022, both readers) and the diffuse anaplastic subtype demonstrated significantly higher 75th-percentile ADC values (p ≤ 0.042, both readers).

Conclusions

Diffusion-weighted MRI may be of value in identifying benign nephroblastomatosis and assessing nephroblastoma subtypes. Therefore, further research is warranted to assess its value in risk stratification for pediatric patients with renal tumors in the future.

[en] To compare morphological and functional MRI metrics and determine which ones perform best in assessing response to neoadjuvant chemoradiotherapy (CRT) in rectal cancer. This retrospective study included 24 uniformly-treated patients with biopsy-proven rectal adenocarcinoma who underwent MRI, including diffusion-weighted (DW) and dynamic contrast-enhanced (DCE) sequences, before and after completion of CRT. On all MRI exams, two experienced readers independently measured longest and perpendicular tumour diameters, tumour volume, tumour regression grade (TRG) and tumour signal intensity ratio on T2-weighted imaging, as well as tumour volume and apparent diffusion coefficient on DW-MRI and tumour volume and transfer constant K"t"r"a"n"s on DCE-MRI. These metrics were correlated with histopathological percent tumour regression in the resected specimen (%TR). Inter-reader agreement was assessed using the concordance correlation coefficient (CCC). For both readers, post-treatment DW-MRI and DCE-MRI volumetric tumour assessments were significantly associated with %TR; DCE-MRI volumetry showed better inter-reader agreement (CCC=0.700) than DW-MRI volumetry (CCC=0.292). For one reader, mrTRG, post-treatment T2 tumour volumetry and assessments of volume change made with T2, DW-MRI and DCE-MRI were also significantly associated with %TR. Tumour volumetry on post-treatment DCE-MRI and DW-MRI correlated well with %TR, with DCE-MRI volumetry demonstrating better inter-reader agreement. (orig.)

[en] Purpose: To assess response of locally advanced rectal carcinoma to chemoradiation with regard to mucinous status and local tumor invasion found at pretherapeutic magnetic resonance imaging (MRI). Methods and Materials: A total of 88 patients were included in this prospective study of patients with advanced mrT3 and mrT4 carcinomas. Carcinomas were categorized by MRI as mucinous (mucin proportion >50% within the tumor volume), and as nonmucinous. Patients received neoadjuvant chemoradiation consisting of 50.4 Gy (1.8 Gy/fraction) and 5-fluorouracil on Days 1 to 5 and Days 29 to 33. Therapy response was assessed by comparing pretherapeutic MRI with histopathology of surgical specimens (minimum distance between outer tumor edge and circumferential resection margin = CRM, T, and N category). Results: A mucinous carcinoma was found in 21 of 88 patients. Pretherapeutic mrCRM was 0 mm (median) in the mucinous and nonmucinous group. Of the 88 patients, 83 underwent surgery with tumor resection. The ypCRM (mm) at histopathology was significantly lower in mucinous carcinomas than in nonmucinous carcinomas (p ≤ 0.001). Positive resection margins (ypCRM ≤ 1 mm) were found more frequently in mucinous carcinomas than in nonmucinous ones (p ≤ 0.001). Treatment had less effect on local tumor stage in mucinous carcinomas than in nonmucinous carcinomas (for T downsizing, p = 0.012; for N downstaging, p = 0.007). Disease progression was observed only in patients with mucinous carcinomas (n = 5). Conclusion: Mucinous status at pretherapeutic MRI was associated with a noticeably worse response to chemoradiation and should be assessed by MRI in addition to local tumor staging to estimate response to treatment before it is initiated.

[en] To determine the appearance of rectal cancer on MRI after oxaliplatin-based chemotherapy (ICT) and make a preliminary assessment of MRI's value in predicting response to total neoadjuvant treatment (TNT). In this IRB-approved, HIPAA-compliant, retrospective study between 1 January 2010-20 October 2014, pre- and post-ICT tumour T2 volume, relative T2 signal intensity (rT2SI), node size, signal intensity and border characteristics were assessed in 63 patients (65 tumours) by three readers. The strength of association between the reference standard of histopathological percent tumour response and tumour volume change, rT2SI and lymph node characteristics was assessed with Spearman's correlation coefficient and Wilcoxon's rank sum test. Cox regression was used to assess association between DFS and radiological measures. Change in T2 volume was not associated with TNT response. Change in rT2SI showed correlation with TNT response for one reader only using selective regions of interest (ROIs) and borderline correlation with response using total volume ROI. There was a significant negative correlation between baseline and post-ICT node size and TNT response (r = -0.25, p = 0.05; r = -0.35, p = 0.005, readers 1 and 2, respectively). Both baseline and post-induction median node sizes were significantly smaller in complete responders (p = 0.03, 0.001; readers 1 and 2, respectively). Change in largest baseline node size and decrease in post-ICT node signal heterogeneity were associated with 100% tumour response (p = 0.04). Nodal sizes at baseline and post-ICT MRI correlated with DFS. In patients undergoing post-ICT MRI, tumour volume did not correlate with TNT response, but decreased lymph node sizes were significantly associated with complete response to TNT as well as DFS. Relative T2SI showed borderline correlation with TNT response. (orig.)