MR imaging of the ankle at 3 Tesla and 1.5 Tesla: protocol optimization and application to cartilage, ligament and tendon pathology in cadaver specimens

Abstract

The objective of this study was to optimize ankle joint MR imaging in volunteers at 1.5 Tesla (T) and 3.0 T, and to compare these optimized sequences concerning image quality and performance in assessing cartilage, ligament and tendon pathology in fresh human cadaver specimens. Initially our clinical ankle protocol consisting of T1-weighted (-w), fat-saturated (fs) T2-w, and short tau inversion-recovery fast spinecho (FSE) sequences was optimized at 1.5 T and 3.0 T by two radiologists. For dedicated cartilage imaging, fs-intermediate (IM)-w FSE, fs spoiled gradient echo, and balanced free-precession steady-state sequences were optimized. Using the optimized sequences, thirteen cadaver ankle joints were imaged. Four radiologists independently assessed these images concerning image quality and pathology. All radiologists consistently rated image quality higher at 3.0 T (all sequences p<0.05). For detecting cartilage pathology, diagnostic performance was significantly higher at 3.0 T (ROC-values up to 0.93 vs. 0.77; p<0.05); the fs-IM FSE sequence showed highest values among the different sequences. Average sensitivity for detecting tendon pathology was 63% at 3.0 T vs. 41% at 1.5 T and was significantly higher at 3.0 T for 2 out of 4 radiologists (p<0.05). Compared to 1.5 T, imaging of the ankle joint at 3.0 T significantly improved image quality and diagnostic performance in assessing cartilage pathology.

3.0 T MR imaging of the ankle: Axial traction for morphological cartilage evaluation, quantitative T2 mapping and cartilage diffusion imaging—A preliminary study

“…In the literature, the accuracy in the detection of cartilage lesions of the knee has been reported to be as high as 87% at 1.5 T and 90% at 3.0 T [21]. For MR imaging of the ankle, sensitivity in detection of cartilage lesions varied between 50% at 1.5 T and 75% at 3.0 T [5,6]. A slightly higher sensitivity was found for MR arthrography (MRA) and computed tomography arthrography (CTA) [22].…”

“…Best results were obtained for coronal T1-w MR images with a driven equilibrium pulse. Barr et al reported, that compared to 1.5 T, 3.0 T significantly improved image quality and diagnostic performance in assessing ankle cartilage pathology [6]. IMfs or T2-w fs sequences have been reported to show the best diagnostic performance in the assessment of ankle cartilage [6,24].…”

“…Due to relatively thin cartilage layers surface discrimination and evaluation is challenging [6]. The lack of separation between the surfaces complicates segmentation of the individual tibial and talar cartilage for quantitative MR imaging [7].…”

Modern Cartilage Imaging of the Ankle

“…The distinction between acute and chronic osteochondral lesions is difficult using X-ray and is often only possible taking into account the mechanism and time of the incident. An MRI is indispensable for more extensive diagnosis [9,10].…”

“…Due the small thickness of the cartilage layer, partial volume effects, particularly in the edge region, are possible. According to studies, the sensitivity of the cartilage lesion image varies from 50 % at 1.5 Tesla and 75 % at 3 Tesla field strength [10]; improvements in diagnostic power can be expected as the technology is developed further. In the clinical setting of most institutions, a routine ankle protocol is used that requires high-resolution sequences suitable for the assessment of articular cartilage.…”