Quantitative mapping of acute and chronic PCL pathology with 3 T MRI: a prospectively enrolled patient cohort.

BACKGROUND: The diagnosis of incomplete acute and chronic posterior cruciate ligament (PCL) tears can be challenging with conventional magnetic resonance (MR) imaging, particularly for injuries in which the ligament appears continuous as occurs with chronic PCL tears that have scarred in continuity. Quantitative mapping from MR imaging may provide additional useful diagnostic information in these cases. The purpose of this study was to assess the feasibility of quantifying transverse relaxation time (T2) mapping values at 3 Tesla (T) in a prospectively enrolled patient cohort with chronic PCL tears. METHODS: Twelve subjects with acute or chronic functionally torn PCL, confirmed on clinical exam and posterior knee stress radiographs (with 8 mm or more of increased posterior tibial translation), were enrolled prospectively over a span of 4 years (age: 28-52 years, injury occurred 2 weeks to 15 years prior). Unilateral knee MR images were acquired at 3 T, including a multi-echo spin-echo T2 mapping scan in the sagittal plane. For the six subjects with a continuous PCL on MR imaging the PCL was manually segmented and divided into proximal, mid and distal thirds. Summary statistics for T2 values in each third of the ligament were compiled. RESULTS: Across the six patient subjects with a continuous ligament, the mean T2 for the entire PCL was 36 ± 9 ms, with the highest T2 values found in the proximal third (proximal: 41 ms, mid 30 ms, distal 37 ms). The T2 values for the entire PCL and for the proximal third subregion were higher than those recently published for asymptomatic volunteers (entire posterior cruciate ligament: 31 ± 5 ms, proximal: 30 ms, mid: 29 ms, distal: 37 ms) with similar methodology. CONCLUSION: Mean T2 values were quantified for acute and chronic PCL tears in this prospectively enrolled patient cohort and were higher than those reported for asymptomatic volunteers. This novel approach of using quantitative mapping to highlight injured areas of the posterior cruciate ligament has potential to provide additional diagnostic information in the challenging case of a suspected posterior cruciate ligament tear which appears continuous, including chronic tears that have scarred in continuity and may appear intact on conventional magnetic resonance imaging.

Regional variation of ankle and hindfoot cartilage T2 mapping values at 3 T: A feasibility study.

OBJECTIVE: To develop a method for T2 mapping of the entire tibiotalar/hindfoot articular surfaces and to examine regional T2 variation in asymptomatic volunteers, establishing necessary methods for future T2 mapping work in patients with ankle/hindfoot injury. MATERIALS AND METHODS: Twenty-six asymptomatic volunteers (11 female/13 male, aged 23-64 years in final analysis) underwent sagittal T2 mapping. Tibiotalar and hindfoot cartilage surfaces were segmented by two raters. The tibiotalar joint cartilage was divided into subregions to assess T2 variation across the joint. The articular surface and subregion mean T2 values were compared using Tukey post hoc pairwise comparisons to test for statistical significance. RESULTS AND CONCLUSION: Mean ankle/hindfoot cartilage T2 ranged from 37 ± 3 to 47 ± 7 ms. Tibial plafond mean T2 was significantly different from the middle and posterior subtalar cartilage T2 (both articular surface comparisons resulted in P < .05). Talar dome mean T2 was significantly different from the posterior calcaneal-side and talar-side subtalar cartilage, and middle calcaneal-side subtalar cartilage (P < .05 for all comparisons). Tibial plafond middle versus lateral, anterior versus middle, middle versus posterior, and anterior versus posterior subregion T2 values were significantly different (P < .05 for all comparisons). Talar dome medial versus middle, middle versus lateral, anterior versus middle, and middle versus posterior subregion T2 values were significantly different (P < .05 for all comparisons). Ankle/hindfoot joint cartilage T2 mapping and segmentation was found to be feasible for all cartilage surfaces except the anterior subtalar joint facet. Mean T2 differed significantly between ankle/hindfoot joint and subregion cartilage in asymptomatic volunteers.

Quantitative mapping of glenohumeral cartilage in asymptomatic subjects using 3 T magnetic resonance imaging.

OBJECTIVE: The purpose of this study was to develop quantitative T2 mapping methodology in asymptomatic shoulders for the entire mappable region of the glenohumeral cartilage in the coronal and sagittal planes, to assess the feasibility and limitations of the development of a diagnostic tool for future application in symptomatic patients. MATERIALS AND METHODS: Twenty-one asymptomatic volunteers underwent sagittal and coronal glenohumeral T2 mapping, as the spherical geometry of the humeral head obviates the need to evaluate the entire glenohumeral cartilage in a single plane. The humeral head cartilage orthogonal to the mapping plane was manually segmented in the sagittal and coronal planes, whereas the glenoid cartilage was segmented in the coronal plane. Cartilage T2 summary statistics were calculated and coverage in each mapping plane was qualitatively assessed. RESULTS: The mean ± standard deviation of the glenoid cartilage T2 was 38 ± 2 ms. The coronal and sagittal mapping planes captured different regions of the humeral head with some overlap: inferior-medial to superior-lateral versus superior/superior-lateral to anterior-lateral and posterior-lateral respectively. The mean humeral head cartilage T2 in the coronal plane was 41 ± 3 ms, which was significantly different (p < 0.05) from the sagittal plane mean of 34 ± 2 ms. CONCLUSION: This study measured characteristic glenoid and humeral head cartilage T2 values over the area mappable with two planes. Importantly, this study demonstrated that two-dimensional mapping in a single plane or two combined planes cannot capture the entirety of the semi-spherical humeral head cartilage. This highlights the need for three-dimensional T2 mapping techniques in the shoulder.