Micro- and Macroscale Assessment of Posterior Cruciate Ligament Functionality Based on Advanced MRI Techniques

Abstract

T2 mapping assesses tissue ultrastructure and composition, yet the association of imaging features and tissue functionality is oftentimes unclear. This study aimed to elucidate this association for the posterior cruciate ligament (PCL) across the micro- and macroscale and as a function of loading. Ten human cadaveric knee joints were imaged using a clinical 3.0T scanner and high-resolution morphologic and T2 mapping sequences. Emulating the posterior drawer test, the joints were imaged in the unloaded (δ0) and loaded (δ1) configurations. For the entire PCL, its subregions, and its osseous insertion sites, loading-induced changes were parameterized as summary statistics and texture variables, i.e., entropy, homogeneity, contrast, and variance. Histology confirmed structural integrity. Statistical analysis was based on parametric and non-parametric tests. Mean PCL length (37.8 ± 1.8 mm [δ0]; 44.0 ± 1.6 mm [δ1] [p < 0.01]), mean T2 (35.5 ± 2.0 ms [δ0]; 37.9 ± 1.3 ms [δ1] [p = 0.01]), and mean contrast values (4.0 ± 0.6 [δ0]; 4.9 ± 0.9 [δ1] [p = 0.01]) increased significantly under loading. Other texture features or ligamentous, osseous, and meniscal structures remained unaltered. Beyond providing normative T2 values across various scales and configurations, this study suggests that ligaments can be imaged morphologically and functionally based on joint loading and advanced MRI acquisition and post-processing techniques to assess ligament integrity and functionality in variable diagnostic contexts.

UTE-T2* versus conventional T2* mapping to assess posterior cruciate ligament ultrastructure and integrity—an in-situ study

“…To assess and quantify regional differences within the PCL, the PCL was further divided into three subregions for additional region-of-interest analysis. To this end, the length of the PCL was automatically determined using 3D centerlines, and the PCL was divided into thirds as published before ( 18 , 22 ) ( Figure 1 ). For the PCL partial and PCL complete conditions, the transected ligament portions (i.e., the transection sites) were manually excluded from the segmentation outlines ( Figure 1B,1C ).…”

“…In their pilot study of six patients with morphologically continuous, yet functionally insufficient PCLs, they found higher T2 relaxation times as compared to asymptomatic volunteers ( 16 ). Other studies consolidated the scientific evidence and investigated T2 mapping of the PCL in the context of osteoarthritis ( 17 ) and loading ( 18 ).…”

Lorentzian-Corrected Apparent Exchange-Dependent Relaxation (LAREX) Ω-Plot Analysis—An Adaptation for qCEST in a Multi-Pool System: Comprehensive In Silico, In Situ, and In Vivo Studies

“…Histological preparation: Following the MRI examination, the specimens were subjected to a standard histological procedure [58]. For this purpose, the IVDs and adjacent vertebrae were decalcified and fixed in Ossa fixona (Diagonal, Münster, Germany), dehydrated, and embedded in paraffin.…”

Evaluation of Sodium Relaxation Times and Concentrations in the Achilles Tendon Using MRI

“…As pathologies such as tendinopathy or tendon rupture are characterized by less orderly arranged collagen structures and increased water content, they can be measured using 1 H T 2 and ultra short echo time (UTE) T 2 * mapping [3,[13][14][15][16]. Other techniques such as chemical exchange saturation transfer (CEST), T 1 ρ, and 23 Na imaging indicate promising results to assess biochemical components such as PG and GAG content [17][18][19][20].…”