QUANTIFICATION OF THE VOLUME OF ARTICULAR-CARTILAGE IN THE METACARPOPHALANGEAL JOINTS OF THE HAND - ACCURACY AND PRECISION OF 3-DIMENSIONALMR-IMAGING

OBJECTIVE. Cartilage loss is central to the development of joint failu re in arthritis, However, radiographic assessment of cartilage loss is highly unreliable. This study examined the accuracy and reproducibili ty of a noninvasive technique for quantifying the volume of articular cartilage in the metacarpophalangeal joints of the hand by use of thre e-dimensional (3D) MR imaging. SUBJECTS AND METHODS. Eight metacarpoph alangeal joints (four normal, one rheumatoid arthritic, and three norm al cadaveric) each were imaged three times with a 1.5-T clinical MR im aging scanner with a small partial volume coil and a fat-saturated 3D spoiled gradient-echo sequence optimized for delineating articular car tilage. The volumes of cartilage over the metacarpal and phalangeal su rfaces were quantified by summing the voxels within segmented 3D recon structions of the images. Cartilage volumes in the three cadaver joint s also were estimated by scraping cartilage off the articular surfaces and measuring water displacement in graduated cylinders. These values were used as the gold standard for assessing the accuracy of cartilag e volume quantification by MR imaging. RESULTS. The fat-saturated sequ ence discriminated the articular cartilage from adjacent joint structu res with high contrast and high spatial resolution, Cartilage volumes determined by MR imaging for the different subjects ranged from 115 mu l to 222 mu l for metacarpal cartilage and from 34 mu l to 86 mu l fo r proximal phalangeal cartilage. Accuracy errors for quantifying carti lage volume by MR imaging were -1.8% (95% confidence interval, -3.5% t o -0.7%) for metacarpal cartilage and 9.1% (4.3% to 14.7%) for proxima l phalangeal cartilage. Reproducibility errors were 5.2% (95% confiden ce interval, 2.9% to 7.6%) and 9.9% (5.4% to 15.1%), respectively. CON CLUSION. Fat-suppressed T1-weighted 3D MR imaging provides sufficient contrast and spatial resolution to allow accurate and reproducible qua ntification of articular cartilage volume in the metacarpophalangeal j oints of the hand. This technique may be useful for monitoring cartila ge loss in patients with arthritis.