Subregional Anatomical Distribution of T2 Values of Articular Cartilage in Asymptomatic Hips

Abstract

Objective:A standardized definition of normative T2 values across the articular surface of the hip must be defined in order to fully understand T2 values for detecting early degeneration. Therefore, in this article, we seek to lay foundational methodology for reproducible quantitative evaluation of hip cartilage damage using T2 mapping to determine the normative T2 values in asymptomatic individuals.Design:Nineteen prospectively enrolled asymptomatic volunteers (age 18-35 years, males 10, females 9, alpha angle 49.3º ± 7.2º) were evaluated with a sagittal T2 mapping sequence at 3.0 T magnetic resonance imaging. Acetabular and femoral cartilage was manually segmented directly on the second echo of the T2 mapping sequence by 3 raters, twice. Segmentations were divided into 12 subregions modified from the geographic zone method. Median T2 values within each subregion were compiled for further analysis and interrater and intrarater reliability was assessed.Results:In the femur, the posterior-superior subregion was significantly higher (P ≤ 0.05) than those in the posterior-inferior and anterior-inferior subregions. In the acetabulum, the anterior-inferior subregion was significantly higher (P ≤ 0.001) than in the anterior-superior, middle, and posterior-inferior subregions. T2 values of the posterior-superior subregion were significantly higher (P ≤ 0.05) than the anterior-superior, middle, and posterior-inferior subregions. Interrater agreement was generally fair to good.

Automated analysis of hip joint cartilage combining MR T2 and three‐dimensional fast‐spin‐echo images

“…The acetabular and femoral cartilage plates were manually segmented on the second echo of the T2 mapping sequence (Ho et al ) on a slice‐by‐slice basis for all MR examinations. Two musculoskeletal‐trained radiologists (with 13 and 11 years experience, respectively) performed T2 map segmentations to compare inter‐rater T2 values.…”

Automated segmentation and quantitative analysis of the hip joint from magnetic resonance images

“…(Used with permission from (Chandra et al 2015b;Ho et al 2014) 6.3 Cartilage thickness measurement illustrated on an example 2D slice overlaid with manual cartilage contours. The example slice is assumed to go through the estimated center of the femoral head.…”

“…Another MR dataset provided by the Steadman Philippon Research Institute (SPRI) (Vail, Colorado, USA) as per Chandra et al (2015b);Ho et al (2014), was used in this chapter to obtain the prior information of clinically-defined anatomical subregions for the individual femoral and acetabular cartilage plates. This dataset consists of 24 anonymized volunteers (12 males and 12 females, aged 23-34 years, body masses 53-151 kg) enrolled in an asymptomatic study after subjective scoring, objective clinical examinations and radiological evaluation using the Hip Osteoarthritis MRI Scoring System (HOAMS) (Roemer et al 2011).…”

“…In this chapter, the center of the femoral head is firstly estimated using a joint locator (Nishii et al 2004) and serves as a reference landmark for measuring the cartilage thickness at each vertex of the BCI surface, which aims to mitigate PVE since the cartilage surface is intersected perpendicularly with the line from the femoral Figure 6.2: (a) Partitioned regions with associated regional descriptors for the (top) acetabular and (bottom) femoral cartilages of the hip joint based on manual landmarks (red dots), which were illustrated using a 3D innominate bone volume from the left-side hip joint and a bone volume of proximal femur from the right-side hip joint, respectively; (b) Example manual cartilage segmentation overlaid on both the (left) 3D SPACE and (right) T2 echo as slices of the 3D image volume. (Used with permission from (Chandra et al 2015b;Ho et al 2014)) head center (Mechlenburg et al 2007). At each BCI vertex, a one-directional grey-value profile with the sampling spacing of 0.125 mm is extracted from the voxelization of cartilage segmentations along the direction from the femoral head center to this vertex (see Figure 6.3).…”

“…The subregional analyses of the cartilage morphology deliver advanced surrogate measures to detect small changes of the cartilage initialized in independent subregions, particularly within the weight-bearing region. These partitioned subregion volumes of the cartilage can automatically offer the extracted ROIs for biochemical evaluation using advanced MR technologies such as dGEMRIC (Siversson et al 2014), T2 mapping (Chandra et al 2015b;Ho et al 2014), T1ρ (Rakhra et al 2012). Ideally, these developments can greatly help to obtain a thorough morphological and biochemical patterns of cartilage degeneration within the hip joint, which is significantly important for diagnosis and intervention of hip OA at a very early stage.…”