SENSITIVITY OF LOW‐FIELD T2^* IMAGES FOR DETECTING THE PRESENCE AND SEVERITY OF HISTOPATHOLOGIC MENISCAL LESIONS IN DOGS

Abstract

The sensitivity of low-field magnetic resonance (MR) T2 images for predicting the presence of meniscal lesions was determined in 12 dogs with naturally-occurring cranial cruciate ligament rupture and three control dogs, using histopathology as the reference standard. Previously published grading systems were used to grade the severity of meniscal lesions on MR images, gross inspection and histopathology. Focal areas of increased signal intensity were detected in 11/12 symptomatic dogs and 3/3 control dogs. Lesions mimicking meniscal tears (pseudotears) were identified at junctions between meniscal margins and adjacent connective tissue in control dogs and dogs with naturally occurring disease. Histopathologic lesions were present in all menisci of both symptomatic and control dogs, including the menisci from two affected dogs that appeared grossly normal but were removed and submitted based on MR imaging findings. Histopathologic lesions identified included hyaline cartilage metaplasia and changes in the amount of ground substance and cellularity. The sensitivity of MR imaging for detecting the presence of meniscal histopathologic lesions was 90% in symptomatic dogs and 91% in control dogs. However, agreement between severity scores for the different tests was poor. Low-field MR imaging is a sensitive test for predicting the presence but not severity of meniscal histopathologic lesions in dogs with naturally-occurring cranial cruciate ligament rupture. Findings also supported previous studies indicating that histopathologic lesions can be present in dogs with grossly normal menisci. An improved grading system for comparing MR images and histopathologic severity of meniscal lesions in dogs is needed.

EFFECTS OF OBSERVER ON THE DIAGNOSTIC ACCURACY OF LOW‐FIELD MRI FOR DETECTING CANINE MENISCAL TEARS

“…Effects of individual observer performance on diagnostic accuracy have rarely been reported in veterinary medicine . Published studies have mainly focused on effects of MRI technique on diagnostic accuracy for detecting canine meniscal tears …”

Comparison of High-field and Low-field Magnetic Resonance Imaging of Stifle Joint Disorders in Dogs

“…Whereas Harper et al (2011), using low-field MRI, successfully detected 90% of medial meniscus tears. In the second study T2*-weighted GE sequences were used, which allowed an increase in the identification of meniscal lesions, especially histopathological changes.…”

“…Among them the following may be mentioned: dorsal recumbency with extended (Baird et al 1999, Martig et al 2006 or flexed hindlimbs (Bottcher et al 2010, Tremolada et al 2014, lateral recumbency with various flexion angles of the stifle (Barrett et al 2009, Podadera et al 2014, or even in sternal recumbency (Harper et al 2011). Pujol et al (2011 reported that lateral recumbency with the stifle flexed at 145 o changed the tension of the cranial cruciate ligament and improved its visibility.…”

“…The incidence of meniscal lesions associated with cranial cruciate ligament rupture is 48-77.3%. Most often it affects the medial meniscus and appears as bucket handle tear (Flo and DeYoung 1978, Bennett and May 1991, Baird et al 1999, Bottcher et al 2010, Harper et al 2011). Bennett and May (1991) reported that damage was rarely observed in the lateral meniscus.…”

“…It is the highest grade of meniscal lesion characterized by complex changes of signal. Furthermore, to confirm meniscal lesions they have to be visualized in two different planes (Harper et al 2011).…”