Sj. Erickson et al., HYALINE CARTILAGE - TRUNCATION ARTIFACT AS A CAUSE OF TRILAMINAR APPEARANCE WITH FAT-SUPPRESSED 3-DIMENSIONAL SPOILED GRADIENT-RECALLED SEQUENCES, Radiology, 201(1), 1996, pp. 260-264
PURPOSE: To investigate the cause of the trilaminar appearance within
hyaline cartilage observed on magnetic resonance (MR) images obtained
with a fat-suppressed three-dimensional spoiled gradient-recalled sequ
ence. MATERIALS AND METHODS: The knees of three asymptomatic volunteer
s were imaged with a fat-suppressed, three-dimensional, spoiled gradie
nt-recalled sequence. The field of view, number of phase-encoding step
s, and phase-encoding direction were varied. On each image, the thickn
ess of the patellar and trochlear cartilage was measured in millimeter
s and divided by the pixel dimension, which effectively expressed the
thickness as the number of pixels. Finally, the number of pixels was c
ompared with the number of alternating hyperintense and hypointense li
nes depicted. RESULTS: The number of truncation lines increased as pix
el dimension was reduced by either decreasing the field of view or inc
reasing the number of phase-encoding steps. The accuracy for predictin
g more that three lines with use of an anteroposterior phase-encoding
direction varied between 83% and 92%. The appearance of the cartilage
was altered when phase- and frequency-encoding directions were exchang
ed, but truncation lines were still evident. CONCLUSION: The trilamina
r appearance depicted within hyaline cartilage on MR images obtained w
ith this sequence is predominantly attributable to truncation artifact
rather than to histologic zonal anatomy.