Abstract
Objective The purpose of this observational study was to establish normative data for the canine
menisci using magnetic resonance imaging (MRI).
Methods Ten fresh stifles from five normal male Beagles were obtained from animals with no
known lameness. Conventional MRI and ultrashort echo time (UTE) imaging were performed
and T2* values calculated. Five stifles were assessed histologically.
Results The caudal horn of the medial meniscus had significantly prolonged T2* values (4.6 ± 1.27 ms; p = 0.002) as compared with the cranial horn of the medial meniscus (3.25 ± 0.86 ms),
and the cranial (3.06 ± 0.54 ms) and caudal (3.64 ± 0.72 ms) horns of the lateral
meniscus. Histology demonstrated normal tibial, femoral, interior and peripheral meniscal
margins, and normal cellularity. The medial meniscus was noted to be obliquely oriented
to the scan plane compared with the relatively perpendicular orientation of the lateral
meniscus as compared with the bore of the magnet in a limb-extended orientation.
Clinical Significance Variability of MRI UTE T2* is seen in the normal canine meniscus, with prolongation of the caudal horn, medial
meniscus. Prolongation may be due to magic angle effects, as the medial meniscus of
the Beagle is not perpendicular to the axis of the main magnetic field. Canine meniscal
injury is a common sequela to cruciate tear, and detecting meniscal damage is important
for directing patient care. The non-invasive quantitative MRI technique of UTE imaging
can be used for the evaluation of collagen orientation, while acknowledging inherent
regions of prolongation.
Keywords
meniscus - MRI - UTE - T2* - canine
