An inception-based deep multiparametric net to classify clinical significance MRI regions of prostate cancer.

Objective.Multi-parametric magnetic resonance imaging (MP-MRI) has played an important role in prostate cancer diagnosis. Nevertheless, in the clinical routine, these sequences are principally analyzed from expert observations, which introduces an intrinsic variability in the diagnosis. Even worse, the isolated study of these MRI sequences trends to false positive detection due to other diseases that share similar radiological findings. Hence, the main objective of this study was to design, propose and validate a deep multimodal learning framework to support MRI-based prostate cancer diagnosis using cross-correlation modules that fuse MRI regions, coded from independent MRI parameter branches.Approach.This work introduces a multimodal scheme that integrates MP-MRI sequences and allows to characterize prostate lesions related to cancer disease. For doing so, potential 3D regions were extracted around expert annotations over different prostate zones. Then, a convolutional representation was obtained from each evaluated sequence, allowing a rich and hierarchical deep representation. Each convolutional branch representation was integrated following a special inception-like module. This module allows a redundant non-linear integration that preserves textural spatial lesion features and could obtain higher levels of representation.Main results.This strategy enhances micro-circulation, morphological, and cellular density features, which thereafter are integrated according to an inception late fusion strategy, leading to a better differentiation of prostate cancer lesions. The proposed strategy achieved a ROC-AUC of 0.82 over the PROSTATEx dataset by fusing regions ofKtransand apparent diffusion coefficient (ADC) maps coded from DWI-MRI.Significance.This study conducted an evaluation about how MP-MRI parameters can be fused, through a deep learning representation, exploiting spatial correlations among multiple lesion observations. The strategy, from a multimodal representation, learns branches representations to exploit radio-logical findings from ADC andKtrans. Besides, the proposed strategy is very compact (151 630 trainable parameters). Hence, the methodology is very fast in training (3 s for an epoch of 320 samples), being potentially applicable in clinical scenarios.

Multimodal Contrastive Supervised Learning to Classify Clinical Significance MRI Regions on Prostate Cancer.

Clinically significant regions (CSR), captured over multi-parametric MRI (mp-MRI) images, have emerged as a potential screening test for early prostate cancer detection and characterization. These sequences are able to quantify morphology, micro-circulation, and cellular density patterns that might be related to cancer disease. Nonetheless, this evaluation is mainly carried out by expert radiologists, introducing inter-reader variability in the diagnosis. Therefore, different deep learning models were proposed to support the diagnosis, but a proper representation of prostate lesions remains limited due to the non-alignment among sequences and the dependency of considerable amounts of labeled data for learning. The main limitation of such representation lies in the cross-entropy minimization that only exploits inter-class variation, being insufficient data augmentation and transfer learning strategies. This work introduces a Supervised Contrastive Learning (SCL) strategy that fully exploits the inter and intra-class variability of prostate lesions to robustly represent MRI regions. This strategy extracts lesion sample tuples, with positive and negative labels, regarding a query lesion. Such tuples are involved into an easy-positive, and semi-hard negative mining to project samples that better update the deep representation. The proposed learning strategy achieved an average ROC-AVC of 0.82, to characterize prostate cancer in MRI, using only the 60% of the available annotated data. Clinical relevance - A robust learning scheme that properly finds representations in limited data scenarios to classify clinically significant MRI regions on prostate cancer.

An online deep convolutional polyp lesion prediction over Narrow Band Imaging (NBI).

Polyps, represented as abnormal protuberances along intestinal track, are the main biomarker to diagnose gastrointestinal cancer. During routine colonoscopies such polyps are localized and coarsely characterized according to microvascular and surface textural patterns. Narrow-band imaging (NBI) sequences have emerged as complementary technique to enhance description of suspicious mucosa surfaces according to blood vessels architectures. Nevertheless, a high number of misleading polyp characterization, together with expert dependency during evaluation, reduce the possibility of effective disease treatments. Additionally, challenges during colonoscopy, such as abrupt camera motions, changes of intensity and artifacts, difficult the diagnosis task. This work introduces a robust frame-level convolutional strategy with the capability to characterize and predict hyperplastic, adenomas and serrated polyps over NBI sequences. The proposed strategy was evaluated over a total of 76 videos achieving an average accuracy of 90,79% to distinguish among these three classes. Remarkably, the approach achieves a 100% of accuracy to differentiate intermediate serrated polyps, whose evaluation is challenging even for expert gastroenterologist. The approach was also favorable to support polyp resection decisions, achieving perfect score on evaluated dataset.Clinical relevance- The proposed approach supports observable hystological characterization of polyps during a routine colonoscopy avoiding misclassification of potential masses that could evolve in cancer.