Radiomics modelling in rectal cancer to predict disease-free survival: evaluation of different approaches.

BACKGROUND: Radiomics may be useful in rectal cancer management. The aim of this study was to assess and compare different radiomics approaches over qualitative evaluation to predict disease-free survival (DFS) in patients with locally advanced rectal cancer treated with neoadjuvant therapy. METHODS: Patients from a phase II, multicentre, randomized study (GRECCAR4; NCT01333709) were included retrospectively as a training set. An independent cohort of patients comprised the independent test set. For both time points and both sets, radiomic features were extracted from two-dimensional manual segmentation (MS), three-dimensional (3D) MS, and from bounding boxes. Radiomics predictive models of DFS were built using a hyperparameters-tuned random forests classifier. Additionally, radiomics models were compared with qualitative parameters, including sphincter invasion, extramural vascular invasion as determined by MRI (mrEMVI) at baseline, and tumour regression grade evaluated by MRI (mrTRG) after chemoradiotherapy (CRT). RESULTS: In the training cohort of 98 patients, all three models showed good performance with mean(s.d.) area under the curve (AUC) values ranging from 0.77(0.09) to 0.89(0.09) for prediction of DFS. The 3D radiomics model outperformed qualitative analysis based on mrEMVI and sphincter invasion at baseline (P = 0.038 and P = 0.027 respectively), and mrTRG after CRT (P = 0.017). In the independent test cohort of 48 patients, at baseline and after CRT the AUC ranged from 0.67(0.09) to 0.76(0.06). All three models showed no difference compared with qualitative analysis in the independent set. CONCLUSION: Radiomics models can predict DFS in patients with locally advanced rectal cancer.

DW-MRI predictive factors for radiation-induced vaginal stenosis in patients with cervical cancer.

AIM: To find diffusion-weighted (DW) magnetic resonance imaging (MRI) parameters predictive for radiation-induced vaginal stenosis (VS) in locally advanced cervical cancer (LACC) treated with neoadjuvant chemoradiation therapy (CRT). MATERIALS AND METHODS: Retrospective analysis of 43 patients with LACC who underwent 1.5 T DW-MRI before (baseline), after 2 weeks (early), and at the end of CRT (final). At MRI, vaginal length, thickness, width, and cervical tumour volume (TV) were measured. Vaginal signal intensity at DW-MRI was analysed at final MRI. CRT-induced VS was graded using Common Terminology Criteria for Adverse Events (CTCAE) v4.03. Correlations between DW-MRI and clinical data were made using Wilcoxon's test, Mann-Whitney test, Fisher's exact test, or chi-squared test as appropriate. Receiver operating characteristic (ROC) curves were generated for variables to evaluate diagnostic ability to predict CRT-induced VS using a logistic regression model. RESULTS: Asymptomatic vaginal toxicity (CTCAE Grade 1) was observed in 14 patients and symptomatic CRT-induced VS (CTCAE Grade ≥2) was detected in 29 patients. Baseline TV was higher in Grade 1 than in Grade ≥2 (p=0.013). Median vaginal length, thickness, and width decreased between baseline and final MRI in all patients (p<0.0001) without significant variances between CTCAE grades. Significant differences were observed in DW-MRI patterns (p<0.0001). In Grade ≥2, DWI showed signal loss of vaginal mucosa in 17 patients (63%) and diffuse restricted diffusion of vaginal wall in eight patients (30%). AUC was 0.938 (coefficient=4.72; p<0.001) for DWI and 0.712 (coefficient=-2.623×10 -5; p=0.004) for TV. CONCLUSIONS: This is the first study using DW-MRI for predicting CRT-induced VS. DWI is useful tool in patients with LACC after CRT for early prevention and management strategies for VS.

Photodynamic action of merocyanine 540 on Staphylococcus epidermidis biofilms.

Photodynamic treatment (PDT) has been proposed as a new approach for inactivation of biofilms associated with medical devices that are resistant to chemical additives or biocides. In this study, we evaluated the antimicrobial activity of merocyanine 540 (MC 540), a photosensitizing dye that is used for purging malignant cells from autologous bone marrow grafts, against Staphylococcus epidermidis biofilms. Effect of the combined photodynamic action of MC 540 and 532 nm laser was investigated on the viability and structure of biofilms of two Staphylococcus epidermidis strains, RP62A and 1457. Significant inactivation of cells was observed when biofilms were exposed to MC 540 and laser simultaneously. The effect was found to be light dose-dependent but S. epidermidis 1457 biofilm proved to be slightly more susceptible than S. epidermidis RP62A biofilm. Furthermore, significant killing of both types of cells was attained even when a fixed light dose was delivered to the biofilms. Confocal laser scanning microscope (CLSM) analysis indicated damage to bacterial cell membranes in photodynamically treated biofilms, while disruption of PDT-treated biofilm was confirmed by scanning electron microscopy (SEM).