How to publish diagnostic imaging studies: Common mistakes and recommendations

Diagnostic performance of ultrasonography, bursography and standing magnetic resonance to detect navicular intrabursal pathology in horses with foot pain

BACKGROUND

Navicular intrabursal pathology (NIP) is a common cause of forelimb lameness in horses. An accurate diagnosis of which structure is involved is essential for therapy and prognosis.

OBJECTIVES

The study aimed to compare the diagnostic performance of ultrasonography, bursography and standing magnetic resonance (MRI) imaging as diagnostic tools of the proximal NIP using bursoscopy as the gold standard.

STUDY DESIGN

Prospective blinded study.

METHODS

A total of 21 feet from 17 horses were included. The feet underwent ultrasonography, followed by MRI, and thereafter bursography and bursoscopy. The images were interpreted blindly to document the presence or absence of the podotrochlear lesions. The lesions of interest were dorsal fibrillations (DF) and splits of deep digital flexor tendon (DDFT), adhesions and fibrocartilage defect (FD) of the navicular bone. The accuracy, specificity, sensitivity, positive predictive values and negative predictive values were calculated. Furthermore, the kappa test was used to calculate the inter-observer agreement.

RESULTS

Bursoscopy revealed lesions in 95% (20/21) of the feet. Eighteen DF and 11 split lesions in the DDFT, 19 FD and 8 adhesions were identified. MRI showed accuracy of 94% (17/18, 95% CI 76.2%-99.9%) for DF and 81% (9/11, 95% CI 63.6%-97%) for split lesions in the DDFT, whereas the accuracy for FD was 58% (11/19; 95% CI 36.1%-80.8%). Adhesions with MRI were predicted correctly in only 37.5% (3/8; 95% CI 43%-85.4%) of the feet. Bursography showed with MRI similar accuracy regarding the adhesions. Bursography had accuracy for FD of 68% (13/19; 95% CI 52.8%-91.8%) and DDFT lesions were detected in 85% (17/20, 95% CI 34%-78.2%) of the feet. Ultrasonography predicted DDFT lesions in 65% (13/20, 95% CI 63.6%-96.9%) of the feet, whereas its adhesions' accuracy was 25% (2/8, 95% CI 14.5%-56.9%). The inter-observer agreement was the lowest for ultrasonography compared to MRI and bursography.

CONCLUSIONS

A combination of ultrasonography and bursography can be an alternative to standing MRI when the latter is not an option or is used as complementary tests.

Imaging and Gross Pathological Appearance of Changes in the Parasagittal Grooves of Thoroughbred Racehorses

Simple Summary

Early detection of racehorses at risk of stress fracture is key to reducing the number of horses with catastrophic fractures while racing. Bone changes are often visible in the limbs of Thoroughbred racehorses in work, particularly in the fetlock region. However, it is currently unknown whether some of these changes indicate an impending fracture or are a healthy adaptation to high-speed exercise. This study looks at imaging and gross changes in a specific area (parasagittal grooves (PSGs) of the cannon bone) and the utility of X-ray, computed tomography (CT) and magnetic resonance imaging (MRI) to detect the changes. All fetlock joints were assessed from twenty horses that died during racing or training, including horses with and without fetlock fracture. Overall, X-ray was poor for detecting PSG changes. Some PSG changes on CT and MRI were common in Thoroughbred racehorses and possibly represent normal bone adaptation when seen in clinical cases. However, certain CT and MRI findings were more prevalent in horses with a fracture, possibly indicating microdamage accumulation and increased risk of fracture. Bilateral advanced imaging is recommended in clinical cases of suspected fetlock pathology.

Abstract

(1) Background: Parasagittal groove (PSG) changes are often present on advanced imaging of racing Thoroughbred fetlocks and have been suggested to indicate increased fracture risk. Currently, there is limited evidence differentiating the imaging appearance of prodromal changes in horses at risk of fracture from horses with normal adaptive modelling in response to galloping. This study aims to investigate imaging and gross PSG findings in racing Thoroughbreds and the comparative utility of different imaging modalities to detect PSG changes. (2) Methods: Cadaver limbs were collected from twenty deceased racing/training Thoroughbreds. All fetlocks of each horse were examined with radiography, low-field magnetic resonance imaging (MRI), computed tomography (CT), contrast arthrography and gross pathology. (3) Results: Horses with fetlock fracture were more likely to have lateromedial PSG sclerosis asymmetry and/or lateral PSG lysis. PSG lysis was not readily detected using MRI. PSG subchondral bone defects were difficult to differentiate from cartilage defects on MRI and were not associated with fractures. The clinical relevance of PSG STIR hyperintensity remains unclear. Overall, radiography was poor for detecting PSG changes. (4) Conclusions: Some PSG changes in Thoroughbred racehorses are common; however, certain findings are more prevalent in horses with fractures, possibly indicating microdamage accumulation. Bilateral advanced imaging is recommended in racehorses with suspected fetlock pathology.

Furosemide administration onehour before bone scintigraphy examination in horses does not improve the image quality or reduce the radiation dose rate

This prospective, cross-sectional, pilot study aimed to investigate the effects of furosemide as a diuretic on the image quality of bone scintigraphy performed using ^99m Tc-HDP and to investigate the impact of furosemide on the radiation dose rate. Thirty-one horses undergoing bone scintigraphy were included. The horses were divided into the control (n = 14) and furosemide group (n = 17), which received 1 mg/kg furosemide intravenously 1 h post ^99m Tc-HDP administration. The image quality was assessed subjectively and semi-quantitatively. The bone-to-soft tissue (B:S) ratio was calculated from the counts per pixel of regions of interest (ROI) positioned over the left radial diaphysis (bone ROI) and its caudal soft tissue area (soft tissue ROI). The radiation rate dose (μSv/h) of both groups was measured at 0, 3, 6, 12, 18, and 24 h post ^99m Tc-HDP administration at a distance of 0, 30, and 100 cm from the head, kidney, and pelvis. The results showed no significant differences in the B:S ratio or the radiation dose rate observed between the groups. However, the radiation dose rate decreased by 56% at 3 h post ^99m Tc-HDP administration and keeping a distance of 30 cm reduced the radiation dose rate by 65%. Administering furosemide does not improve the image quality or reduce the radiation dose rate. The authors recommend commencing with bone scintigraphy 3 h post ^99m Tc-HDP administration and keeping at least a distance of 30 cm from the horse to reduce the staff radiation dose.