Joy and Luck of Fixing a Leech

A group of researchers have used microCT to examine and describe a new species of leech, which they named after Amy Tan (the author of Joy Luck Club). The most important part is kind of buried in the Science Daily piece.

For objects smaller than a human, CT has horrible soft tissue contrast. MRI has significantly better soft tissue contrast, regardless of the size of the sample. However, microCT has better spatial resolution compared to preclinical or ‘microMRI’ if you will. This group used a microCT that is not intended for live specimen and can reach 5 micron resolution.

The research presented here is a fantastic example of how science works, i.e., building on previous work, especially if it is in a different area. For those of you who remember high school biology, you probably had to dissect a frog or something from a jar. That stinky liquid is formaldehyde, which is what preserves the specimen. It’s known as a fixative. So this group looked at fixatives that are typically used in scanning electron microscopy. One of them was osmium tetroxide, which binds the metal osmium to give better contrast. The recipe that worked best was using AFA (alcohol, formalin (which is a variant of formaldehyde), and acetic acid) as the primary fixative, followed by osmium tetroxide.

Unlike the BaSO4 method I wrote about earlier, this method involves soaking the sample for several hours (6-12).

The other key part is in the visualization and image analysis tools. Identifying the various internal organs uses a tool called segmentation. Sometimes it’s automated and sometimes you have to do it manually.

Since I’m heading out to walk my dog, I’ll keep this short and give you a few links if you wish to read more.

Medical Imaging 101 pt 2: CT

http://goo.gl/IHaFw

Fast CT from GE Healthcare

https://goo.gl/AV6Z59

BaSO4, X-ray Contrast

https://goo.gl/O3GBgU

Medical visualization, it’s what I see and do

http://goo.gl/PrwLx6

GE phoenix v|tome|x s scanner

https://goo.gl/aOsbv2

edit

Here’s the Science Daily article.

http://www.sciencedaily.com/releases/2016/01/160121130702.htm

Full article here:

1. Michael Tessler, Amalie Barrio, Elizabeth Borda, Rebecca Rood-Goldman, Morgan Hill, Mark E. Siddall. Description of a soft-bodied invertebrate with microcomputed tomography and revision of the genusChtonobdella(Hirudinea: Haemadipsidae). Zoologica Scripta, 2016; DOI: 10.1111/zsc.12165

http://dx.doi.org/10.1111/zsc.12165

h/t rasha kamel 

http://www.youtube.com/watch?v=QnRCxFKroXA