FEASIBILITY FOR MAPPING CARTILAGE T1 RELAXATION TIMES IN THE DISTAL METACARPUS3/METATARSUS3 OF THOROUGHBRED RACEHORSES USING DELAYED GADOLINIUM‐ENHANCED MAGNETIC RESONANCE IMAGING OF CARTILAGE (dGEMRIC): NORMAL CADAVER STUDY

Abstract

Osteoarthritis of the metacarpo/metatarsophalangeal joints is one of the major causes of poor performance in horses. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) may be a useful technique for noninvasively quantifying articular cartilage damage in horses. The purpose of this study was to describe dGEMRIC characteristics of the distal metacarpus3/metatarsus3 (Mc3/Mt3) articular cartilage in 20 cadaver specimens collected from normal Thoroughbred horses. For each specimen, T1 relaxation time was measured from scans acquired precontrast and at 30, 60, 120, and 180 min post intraarticular injection of Gd-DTPA(2-) (dGEMRIC series). For each scan, T1 relaxation times were calculated using five regions of interest (sites 1-5) in the cartilage. For all sites, a significant decrease in T1 relaxation times occurred between precontrast scans and 30, 60, 120, and 180 min scans of the dGEMRIC series (P < 0.0001). A significant increase in T1 relaxation times occurred between 60 and 180 min and between 120 and 180 min post Gd injection for all sites. For sites 1-4, a significant increase in T1 relaxation time occurred between 30 and 180 min postinjection (P < 0.05). Sites 1-5 differed significantly among one another for all times (P < 0.0001). Findings from this cadaver study indicated that dGEMRIC using intraarticular Gd-DTPA(2-) is a feasible technique for measuring and mapping changes in T1 relaxation times in equine metacarpo/metatarsophalangeal joint cartilage. Optimal times for postcontrast scans were 60-120 min. Future studies are needed to determine whether these findings are reproducible in live horses.

Recent advances in articular cartilage evaluation using computed tomography and magnetic resonance imaging

“…There are few equine studies implementing dGEMRIC . In one study, dGEMRIC was used to predict metacarpophalangeal joint cartilage thickness with high accuracy and repeatability, except at sites in contact with proximal phalanx cartilage .…”

Use of contrast media in computed tomography and magnetic resonance imaging in horses: Techniques, adverse events and opportunities

“…Intraarticular administration is less common due to off-label designations in man but is generally accepted at~2-4 mmol/L [96,235]. In horses, dGEMRIC is used [233,[238][239][240][241], although thin cartilage in the metacarpophalangeal joint reduces segmentation accuracy due to volume averaging [242] and long acquisition times remain a challenge [233]. Use of dGEMRIC includes a 90 min delay to allow sufficient diffusion into articular cartilage, while exercise, joint loading and cartilage thickness influence uptake [236,237].…”

“…Use of dGEMRIC includes a 90 min delay to allow sufficient diffusion into articular cartilage, while exercise, joint loading and cartilage thickness influence uptake [236,237]. In horses, dGEMRIC is used [233,[238][239][240][241], although thin cartilage in the metacarpophalangeal joint reduces segmentation accuracy due to volume averaging [242] and long acquisition times remain a challenge [233]. A recently developed cationic agent shows better penetration at 10% the dose of an anionic GCM and holds promise for improved dGEMRIC techniques [243].…”

Letter to the Editor

“…Recently, two studies aiming to validate quantitative MR imaging of the articular cartilage of the equine fetlock were published in Veterinary Radiology and Ultrasound . Delayed gadolinium‐enhanced magnetic resonance imaging and T2 mapping of cartilage have the potential to quantify parameters of cartilage degeneration and I am pleased to see that these modalities are now being introduced in veterinary imaging.…”

“…The second paper from the same authors, entitled “Feasibility for mapping cartilage T1 relaxation times in the distal metacarpus3/metatarsus3 of Thoroughbred racehorses using delayed Gadolinium‐enhanced magnetic resonance imaging of cartilage (dGEMRIC): Normal cadaver study,” also suffers from a lack of spatial resolution. The situation is a bit more complex than in the previous manuscript since the authors here are not investigating linear distance measurements but T1 relaxation measurements.…”