MR imaging truncation artifacts can create a false laminar appearance in cartilage

OBJECTIVE. The purpose of this study was to investigate the laminar appearance of cartilage on MR images. MATERIALS AND METHODS. Theoretical modeling of truncation artifacts was used to predict spatial patterns and associated intensity Variations in MR imaging. A numerical simulation of a ring model was used to show truncation artifacts as a function of the angle in the image plane for unequal in-plane resolutions. MR imaging of 10 cadaveric human patellae at several resolutions used an imaging protocol that produced high-contrast images of cartilage. The high-resolution image of each MR imaging set was reduced in resolution by low-pass filtering and compared with the acquired images of equivalent resolution. Variable-resolution images of the patella of a healthy human volunteer were also acquired. RESULTS. Truncation artifacts from opposing cartilage edges can create false laminae and artifactual intensities. The resulting geometric variations can alter the apparent width of the cartilage as well. The intensity variations produced by truncation artifacts can be as much as 22% of the actual intensity. The most pronounced artifactual trilaminar appearance occurs when cartilage thickness exceeds the image resolution by a factor of 4. Truncation artifacts vary as a function of the angle in the imaging plane for unequal resolutions in the two directions. CONCLUSION. Truncation artifacts can produce an artifactual laminar appearance in cartilage and alter the apparent cartilage width.