A three‐dimensional quantitative method to measure meniscus shape, position, and signal intensity using MR images: A pilot study and preliminary results in knee osteoarthritis

Abstract

This pilot study presents a technique for three-dimensional and quantitative analysis of meniscus shape, position, and signal intensity and compares results in knees with (n 5 20) and without (n 5 11) radiographic osteoarthritis. 3-T MR images with 2mm section thickness were acquired using a proton density-weighted, fat-suppressed, coronal, fast spinecho sequence. Segmentation of the tibial, femoral, and external surface of the medial meniscus and the tibial joint surface was performed. Three-dimensional parameters were computed to describe the shape, position, and signal intensity of the entire meniscus and three subregions (body, anterior, and posterior horn). Key results included a greater size (i.e., volume, surface areas, and thickness), increased medial extrusion (i.e., greater extrusion distance, greater meniscal area uncovered by tibial surface), and elevated signal intensity of the medial meniscus in osteoarthritis than in nonosteoarthritis knees, particularly in the meniscus body. These results need to be confirmed in larger cohorts, preferably under weight-bearing conditions. Magn Reson Med 63:1162-1171, 2010. V C 2010 Wiley-Liss, Inc.Key words: meniscus; osteoarthritis; extrusion; coverageThe meniscus plays an important role in normal knee function by providing a higher degree of joint conformity (congruity) and by distributing loads over a wider area (1). Meniscal pathology (i.e., extrusion and tears) is frequent in the general population, even among asymptomatic individuals, and becomes more common with increasing age (2). Meniscal pathology has also been associated with knee pain (3-6) and osteoarthritis (OA) progression, specifically with increased rates of cartilage loss (7-12). These findings have generally relied on semiquantitative scoring of the meniscus (4,13), and only few studies have utilized quantitative measures of meniscus position (subluxation) or shape (14-16).Gale et al. (14) used coronal fat-saturated proton density and T 2 -weighted images to investigate the relationship between meniscal extrusion (subluxation) and joint space narrowing in 233 participants with symptomatic knee OA and in 58 asymptomatic controls. They determined the degree of extrusion to the nearest millimeter in the image where the greatest distance between the most peripheral aspect of the meniscus and the border of the tibia (excluding osteophytes) was observed. The OA participants displayed more extrusion of the medial meniscus (MM) than controls (5.1 versus 2.8mm; P ¼ 0.001). Modest degrees of meniscal extrusion were common in controls, but severe degrees (>7mm) were unique to OA cases. Hunter et al. (15) explored the role of meniscal tears (semiquantitative scoring (13)), extrusion, and height as risk factors for cartilage loss in 257 subjects. Extrusion and height were measured quantitatively in the coronal MR image showing the maximal medial tibial spine volume and in two sagittal images, one through the medial and one through the lateral tibia. Meniscal coverage and height were smaller in knees with men...

Automated Image Analysis of High-field and Dynamic Musculoskeletal MRI

“…Previous studies have used MR imaging to study the morphology of the meniscus in relation with knee OA [Wirth 2010]. The volume, subluxation and tibial-coverage area of the meniscus have been established as important biomarkers of disease progression, with significant differences identified across patients with variably advanced knee OA [Wenger 2013, Blöcker 2013].…”

“…New developments in quantitative magnetic resonance (MR) imaging have generated considerable clinical interest for the design of methods to study the morphology and biochemical composition of the medial meniscus (MM), lateral meniscus (LM) and PCL in relation to knee injuries and OA [Wirth 2010, Wenger 2013, as well as for the assessment of in-vivo 3D knee kinematics using dynamic MR imaging (e.g., contact mechanisms between cartilages [Borotikar 2012]). These measurements offer avenues to study early pathophysiological changes associated with pre-osteoarthritic degeneration (e.g., reorganisation of the extracellular matrix of the meniscus affecting normal function [Juras 2014, Zarins 2010); assess the structural integrity of the menisci and ligaments post-surgery (e.g., healing properties of the tissues [Chu 2014, Biercevicz 2014a); or investigate abnormal bone tracking or contact mechanisms in PFPS [Pal 2013] or in ligament-deficient patients [Barrance 2006] for predicting subsequent risks of cartilage wear.…”

“…The MM and LM in MR images of knee joints with confirmed rOA are often visibly torn, macerated or substantially destructed [Bennett 2002, Chan 1991 with OA development [Wirth 2010, Blöcker 2014. Quantitative biochemical MR analyses such as T 1ρ -, T 2 -and T * 2 -mapping, on the other hand, may provide clinical information regarding meniscal tissue health that can influence treatment decision and prognosis in injury states (e.g., the meniscus may have an inferior ability to heal when repaired).…”

“…In recent years, several fully-quantitative MR analysis methods have been proposed to study the burden of knee OA and monitor progression [Wirth 2010], allowing the identification of a number of important morphological factors of the knee menisci (mainly volume, subluxation and tibial-coverage) associated with knee rOA [Blöcker 2013, Hwang 2012, Wenger 2013] (for extensive review, see Section 3.1.1). Besides quantifying the morphology of the MM and LM, several studies have suggested that T 1ρ -, T 2 -and T * 2 -mapping of the menisci were sensitive to the increased water content and mobility within the tissues which may result from the deterioration of the collagen network or proteoglycan loss.…”

“…Previous clinical studies relied on the manual or semi-automated segmentation of the menisci in the MR images to extract these important quantitative measurements (e.g., [Wirth 2010, Chu 2014). …”