# Does Low-Field MRI Tenography Improve the Detection of Naturally Occurring Manica Flexoria Tears in Horses?

## TL;DR

This study compares different imaging techniques for detecting manica flexoria tears in horses and finds that low-field MRI tenography performs similarly to contrast radiography.

## Contribution

The study evaluates the diagnostic performance of MRIt in detecting MF tears in horses and compares it with other modalities.

## Key findings

- MRIt and contrast radiography showed equal sensitivity (71%) and perfect specificity (100%) for detecting MF tears.
- MRI and ultrasonography had lower sensitivity (57%) but MRI had higher specificity (100% vs. 33%).
- MRIt did not improve diagnostic performance over contrast radiography but provided lesion laterality information.

## Abstract

Diagnosing digital flexor tendon sheath (DFTS) pathologies, particularly manica flexoria (MF) tears, can be challenging with standard imaging modalities. Standing DFTS MRI tenography (MRIt) may improve the pre-operative diagnosis of MF lesions. This study aimed to assess the diagnostic performance of ultrasonography, contrast radiography, native MRI, and MRIt for detecting naturally occurring MF lesions in horses undergoing tenoscopy. Ten horses with a positive DFTS block, ultrasonographic and contrast radiographic examination, MRI, MRIt, and tenoscopy were included. Two radiologists retrospectively evaluated the images and recorded whether an MF lesion was present. Sensitivity and specificity were calculated for each modality using tenoscopy as the reference, and the values were compared using McNemar’s tests. MF lesions were identified with equal frequency using the MRIt and contrast radiography, both showing a sensitivity of 71% and a specificity of 100%. The MRI and ultrasonography detected MF lesions with the same sensitivity of 57.1%, but the MRI demonstrated higher specificity compared to ultrasonography (100% and 33%). There was no statistically significant difference between the imaging modalities for detecting MF lesions (p = 1). Specifically, MRIt and contrast radiography each detected five out of seven MF lesions, while MRI and ultrasonography each detected four out of seven lesions. MRIt did not enhance the diagnostic performance of low-field MRI to diagnose naturally occurring MF tears in horses. Furthermore, neither the MRI nor MRIt demonstrated superiority over contrast tenography, except in the diagnosis of lesion laterality. Compared with ultrasonography, which exhibited a rather low specificity, both MRI and MRIt may better distinguish an intact from a torn MF.

Diagnosing digital flexor tendon sheath (DFTS) pathologies, particularly manica flexoria (MF) tears, can be challenging with standard imaging modalities. Standing low-field MRI tenography (MRIt) may improve the detection rate of MF tears. This study aimed to compare ultrasonography, contrast radiography, pre-contrast MRI, and MRIt to detect naturally occurring MF lesions in horses undergoing tenoscopy. Ten horses with a positive DFTS block, which underwent contrast radiography, ultrasonography, MRI, MRIt, and tenoscopy were included. Two radiologists evaluated the images and recorded whether an MF lesion was present and determined the lesion side. Sensitivity and specificity were calculated for each modality using tenoscopy as a reference. MRIt and contrast radiography detected MF lesions with the same frequency, both showing 71% sensitivity and 100% specificity. Pre-contrast MRI and ultrasonography detected MF lesions with a lower sensitivity (57%); however, the MRI (100%) demonstrated a higher specificity than ultrasonography (33%). Adding contrast in MRI changed the sensitivity from (4/7 lesions) 57% to (5/7 lesions) 71%, with a constant high specificity (100%). MRIt diagnoses MF tears with a similar sensitivity to contrast radiography, with the same specificity, but with the added benefit of lesion laterality detection. The combined advantages of the anatomical detail of the T1 sequence and the post-contrast hyperintense appearance of the fluid may help diagnose MF tears and identify intact MFs. However, this needs to be substantiated in a larger number of cases.