Computer Vision News - February 2023

43 RnR-ExM Robust Non-rigid Registration... Expansion microscopy is a technique to image small tissue samples that would not otherwise be visible on a microscopic level. A gel polymer is used to expand the sample, similar to how diapers expand when wet. “ Expansion microscopy is really novel, but it also presents some interesting challenges when it comes to registration, ” Emma tells us. “ The labs do multi-round imaging , where the same tissue sample is stained multiple times and sometimes over multiple days. When this happens, it can deform, lose staining intensity, and become noisier when you image it. We thought this would lend itself to a good challenge. ” The organizers have provided diverse data for participants to register generated from the Boyden lab , including C. elegans, zebrafish, and mouse data. These animals are considered model organisms in the biology community. The project aims to develop a benchmark data set for expansion microscopy image registration , which could be used in tandem with developing new registration methods. There are already benchmark datasets for other medical imaging modalities, such as MRI and CT, but to the team’s knowledge, none have been developed to date for expansion microscopy. An ideal result from this challenge, Emma reveals, would be to see many different approaches to registering the microscopy images , including learning- based and traditional optimization-based approaches, as well as runtimes for each and a quantitative assessment of how they compare against each other. This work involves massive data, so accuracy alone is not enough. “ We’re asking participants to submit runtimes on a purely honor-code basis, ” she reveals. “ The time it takes to register the images doesn’t necessarily affect the registration quality. It’s a small part of the experiment but can be super time- consuming. Five hundred volumes might need to be registered from all the different staining grounds for a single experiment. Finding methods to reduce the time it takes to do this step is important. ” With the window for submission of results opening shortly, does Emma have any last- minute tips for participants? Donglai Wei