THE EFFECT OF MAGNETIZATION-TRANSFER IN MENISCAL FIBROCARTILAGE

Magnetic resonance imaging of the knee was performed in 28 patients (a ges 15-72 years), using a 1.5-T unit. Volume gradient echo (3D GRASS) acquisition with and without presaturation off-resonance RF pulse was used to evaluate magnetization transfer (MT) effects, determined by pl acing regions of interest on muscle, fat, hyaline, and fibrocartilage; the percent change in signal intensity was calculated and compared us ing a paired two-sample t test. An in vitro study of the normal menisc us from a cadaver containing a scalpel cut extending to an articular s urface was performed to observe the relative improvement in contrast i n the presence of a small meniscal defect. MR imaging of the specimen was performed using an Omega CSI 2.0-T system (General Electric Medica l Systems, Fremont, CA). Analysis of clinical images resulted in signa l loss, compared to that of the identically timed and tuned non-MT ima ges of 47 +/- 5, 8 +/- 5, 49 +/- 5, and 57 +/- 7% for muscle, fat, art icular cartilage and fibrocartilage, respectively. Application of MT i mproved the depiction of the artificially introduced meniscal defect. Meniscal fibrocartilage demonstrates significant MT effect after appli cation of off-resonance RF presaturation, which may improve visualizat ion of meniscal defects.