https://sites.uw.edu/eradsite/trauma-radiology-reference-resource/tutorials/

Presenter: Jon A. Jacobson, MD FACR Link: https://us02web.zoom.us/rec/share/wF4yHXiZxiBBnZepcSrfefAPRh0mY6agpGCkitb-UaQiATCnrAh6QpT5YaJyAEiI.1qvAGvS2dzS8ZOA5

https://www.ajronline.org/doi/10.2214/AJR.18.19712

Hi Guys, here a quick example of different settings in PD- and intermediate weighted spin echo sequences for MSK radiology and their influence on the cartilage appearance: 3 Sequences done on the same Patient with following TR/TE-timings: 1: TR2400 TE42 (classic intermediate weighted) 2: TR1650 TE42 (experimental "hybrid" sequence just as an example) 3: TR 1650 TE17 (classic proton weighed images) This gives besides a good review also an overview of the different settings in a table: Systematic review of techniques in cartilage imaging - ScienceDirect Following source explaines in detail why you got darker parts in your healthy cartilage close to the subchondral plate. Proteogycanes interact with the protons bound in the hyaline cartilage and accelerate their T2-decay. If you start receiving signals with a TE grater 20-30 you will miss their signals (aleady gone) and the region appears darker. Interpretation of Cartilage Damage at Routine Clinical MRI: How to Match Arthroscopic Findings | RadioGraphics (rsna.org) By the way: The article concludes, that the most precise type of imaging is PD-Sequences for cartilage when compared to finding during surgery. But the images from our patient show also the downside of true PD-Sequences: More magic angle artifacts and "perseveration" of minimal degenerative features in the images (compare the meniscal structures). Turning down the TR from 2400 to 1650 (image 1 vs 2) has no significant influence in my opinion. Changing TE from 42 to 17 therefore gives a very homogenious cartilage signal in this healthy patient. At the femurcondyle you can appreciate residual signal loss very close to the subchondral plate even in the image 3, that could not be erased. Hope that's a help to some of you understanding the different appearance of cartilage in different Sequences or different MRI machines with alternating setting.