Live 4D-OCT denoising with self-supervised deep learning.

By providing three-dimensional visualization of tissues and instruments at high resolution, live volumetric optical coherence tomography (4D-OCT) has the potential to revolutionize ophthalmic surgery. However, the necessary imaging speed is accompanied by increased noise levels. A high data rate and the requirement for minimal latency impose major limitations for real-time noise reduction. In this work, we propose a low complexity neural network for denoising, directly incorporated into the image reconstruction pipeline of a microscope-integrated 4D-OCT prototype with an A-scan rate of 1.2 MHz. For this purpose, we trained a blind-spot network on unpaired OCT images using a self-supervised learning approach. With an optimized U-Net, only a few milliseconds of additional latency were introduced. Simultaneously, these architectural adaptations improved the numerical denoising performance compared to the basic setup, outperforming non-local filtering algorithms. Layers and edges of anatomical structures in B-scans were better preserved than with Gaussian filtering despite comparable processing time. By comparing scenes with and without denoising employed, we show that neural networks can be used to improve visual appearance of volumetric renderings in real time. Enhancing the rendering quality is an important step for the clinical acceptance and translation of 4D-OCT as an intra-surgical guidance tool.

A survey of acute pain service in Canadian teaching hospitals.

BACKGROUND: The first national survey to ascertain the prevalence, structure, and functioning of the APS in Canadian university affiliated hospitals was conducted in 1991. This is a follow-up survey to assess the current status of the APS in Canada. METHODS: We requested completion of a 26-question survey from lead personnel of the APS teams or Anesthesia departments of Canadian teaching hospitals. RESULTS: Among the 32 centers that were contacted, 21 (65.6%) responded. Of these respondents, 18 (85.7%) indicated that they have a structured APS (72.22% adults, 5.56% pediatrics, 22.22% mixed). Among the 18 centers with an APS, 16 of the services are led by an anesthesiologist. Eight centers (44.44%) have a regional anesthesia group, of which five (27.75%) have a regional anesthesia group that is distinct from the APS team. Nine centers (50%) offer ambulatory nerve catheter analgesia after discharge home. Fifteen centers (83.33%) use standardized order sets, and 13 centers (72.22%) use an electronic record for APS. More than 50% of the centers use intravenous lidocaine and ketamine as a part of their multimodal analgesia. CONCLUSION: Most Canadian teaching hospitals do have a functioning APS. This survey has the potential to generate research questions about the availability of standardized and advanced acute pain management in Canada's teaching hospitals.