Young-Sun Kim MD, PRESENTER: Nothing to Disclose

Abstract: HTML Purpose: Low intensity line (LIL) on the surfaces of or between articular cartilages of knee can be seen on fast spin-echo MR image. It may mimic discoid meniscus when prominent. Purpose of this study is to know if LIL is true lesion or not, and to evaluate the relationship between visibility of LIL and degree of degeneration of knee joint. Methods and Materials: Retrospectively, we reviewed 148 knee MR of 145 patients (M:F=77:68, mean age=39.4) who have no pathology directly affecting articular cartilage other than osteoarthritis. We graded the visibility of LIL of medial and lateral compartment on fast spin-echo proton density-weighted image (0: invisible, 1: disrupted, 2: continuous, thin, irregular, 3: continuous, thick, smooth). Degrees of cartilage loss, spur formation, and meniscal degeneration were examined if they had any correlation with the visibility of LIL. In 28 patients who underwent arthroscopy, cartilage injury of medial knee was assessed with Outerbridge grading (0: normal, 1: softening or minimal irregularity, 2: fibrillation 3: exposure of subchondral bone). Sum of femoral and tibial scores were also correlated with visibility of medial LIL. Results: Lateral LIL showed better visibility than medial LIL (p<.05). The younger, the better visibility of LIL is noted (medial r=-.598, lateral r=-.515, p=.000). Male showed better visibility than female (medial 1.98±.97:1.31±1.19, p=.011, lateral 2.44±0.87:1.69±1.10, p=.004). The degrees of cartilage loss (medial r=-.619, lateral r=-.585, p=.000), spur formation (medial r=-.579, lateral r=-.421, p=.000), and meniscal degeneration (medial r=-.475, lateral r=-.317, p=.000) are correlated more strongly with the visibility of medial LIL than lateral LIL. Arthroscopy found no discoid meniscus. Arthroscopic grading of cartilage injury of medial knee had strong correlation with the visibility of LIL (r=-.717, p=.000). When we regarded the visibility of 0 and 1 on MR as the positivity for cartilage abnormality (Outerbridge 1~3), sensitivity, specificity, positive and negative predictive values were 75%, 83.3%, 85.7% and 71.4%, respectively. Conclusion: LIL should not be misinterpreted as discoid meniscus. Clear LIL on the surfaces of or between articular cartilages of knee on fast spin-echo MR represents healthy cartilage without any degree of degeneration, especially at the medial knee. Indistinct LIL may enable MR diagnosis of very early stage of osteoarthritis.       Questions about this event email: youngsunkim@hanyang.ac.kr

Kim MD, Y, Low Intensity Line on the Surfaces of Articular Cartilages of the Knee Joint on Fast Spin-Echo MR as a Sign of Healthy Cartilage: Arthroscopic Correlations.  Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL. http://archive.rsna.org/2003/3104392.html