Ex vivo comparison of 3 Tesla magnetic resonance imaging and multidetector computed tomography arthrography to identify artificial soft tissue lesions in equine stifles

Abstract

Objective: To determine the diagnostic performance of computed tomographic arthrography (CTA) and 3 Tesla magnetic resonance imaging (MRI) for detecting artificial meniscal, meniscotibial ligament (MTL) lesions and cruciate ligament (CL) lesions in horses.

Study design: Ex vivo controlled laboratory study.

Animals: Nineteen stifles from adult horses.

Methods: Stablike defects (n = 84) (16 mm long, 10 mm deep) were created in the menisci (n = 35), CLs (n = 24), and MTLs (n = 25) via arthroscopy prior to MRI and CTA (80 mL contrast at 85 mg/mL per joint). Two radiologists, unaware of the lesions, reached a consensus regarding the presence of lesions, based on 2 reviews of each study. Sensitivity and specificity of MRI and CTA were determined using arthroscopy as a reference and compared with McNemar's tests.

Results: The sensitivity and specificity of MRI (41% and 86% respectively) and CTA (32% and 90% respectively) did not differ (P = .65). The sensitivity (MRI: 24%-50%; CTA:19%-40%) and specificity (MRI: 75%-92%; CTA 75%-100%) of imaging modalities did not differ when detecting lesions of the menisci, MTLs, and CLs (P = .1-1.0). The highest sensitivities were achieved when MTLs were evaluated with MRI (50%) and CLs with both modalities (40%).

Conclusions: The diagnostic performance of CTA was comparable with that of MRI, with a low to moderate sensitivity and high specificity.

Clinical significance: Computed tomographic arthrography should be considered as an adjunct to diagnose CL injuries. This is important for equine clinicians, as the CL cannot be visualized adequately using basic imaging techniques preoperatively.

FIGURE 1

Arthroscopic image of an experimental lesion created in the cranial cruciate ligament (asterisk) via a cranial approach to the lateral femorotibial joint. Abbreviations: LFC, lateral femoral condyle; T, lateral tibial condyle

FIGURE 2

Arthroscopic image of an experimental lesion created in the medial cranial meniscotibial ligament (asterisk) via a cranial approach to the medial femorotibial joint. Abbreviation: MFC, medial femoral condyle

FIGURE 3

Arthroscopic image of an experimental lesion created in the cranial horn of the lateral meniscus (asterisk) via a cranial approach to the lateral femorotibial joint. Abbreviations: LFC, lateral femoral condyle; T, lateral tibial condyle

FIGURE 4

Images A (transverse computed tomographic image), B (sagittal plane computed tomographic image) and C (3D‐T2‐weighted high‐resolution dorsal plane magnetic resonance image) showing a true positive lesion in the cranial meniscotibial ligament (arrowhead) and cranial horn of the lateral meniscus (arrow) in a cadaveric equine stifle. There is a clear linear infiltration of contrast medium/synovial fluid.Note the extravasation of contrast medium/synovial fluid cranial and lateral to the femorotibial joint (x). The long digital extensor tendon is marked by the asterisk

FIGURE 5

Images A (sagittal computed tomographic (CT) image) and B (corresponding T2‐weighted high‐resolution magnetic resonance image (MRI) show a true positive lesion in the caudal cruciate ligament in a cadaveric equine stifle. The caudal cruciate ligament is faintly outlined with contrast medium on CT and shows an abnormal shape with a bulging midportion and thinner distal portion with both modalities (arrows). With CT, the midportion appears mildly hyperdense and, with MRI, an increased signal intensity with mild linear infiltration is seen. The proximal portion is not well delineated on CT and the borders appear mildly irregular on MRI