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Background: Palmar/plantar osteochondral disease (POD) of the metacarpal/tarsal condyles is a common pathological finding in racehorses., Objective: To compare diagnoses, imaging details, and measurements of POD lesions between cone-beam computed tomography CT (CBCT), fan-beam CT (FBCT), and low-field magnetic resonance imaging (MRI) using macroscopic pathology as a gold standard., Study Design: Cross-sectional study., Methods: Thirty-five cadaver limbs from 10 horses underwent CBCT, FBCT, MRI, and macroscopic examination. CT and MR images were examined for presence of POD, imaging details of POD, and measurements of POD dimensions and areas. Imaging diagnoses, details, and measurements were compared with macroscopic examination and between modalities., Results: Forty-eight POD lesions were seen over 70 condyles. Compared with macroscopic examination the sensitivity and specificity of diagnosis were 95.8% (CI95 = 88%-99%) and 63.6% (CI95 = 43%-81%) for FBCT, 85.4% (CI95 = 74%-94%) and 81.8% (CI95 = 63%-94%) for CBCT, and 69.0% (CI95 = 54%-82%) and 71.4% (CI95 = 46%-90%) for MRI. Inter-modality agreement on diagnosis was moderate between CBCT and FBCT (κ = 0.56, p < 0.001). POD was identified on CT as hypoattenuating lesions with surrounding hyperattenuation and on MRI as either T1W, T2*W, T2W, and STIR hyperintense lesions or T1W and T2*W heterogeneous hypointense lesions with surrounding hypointensity. Agreement on imaging details between CBCT and FBCT was substantial for subchondral irregularity (κ = 0.61, p < 0.001). Macroscopic POD width strongly correlated with MRI (r = 0.81, p < 0.001) and CBCT (r = 0.79, p < 0.001) and moderately correlated with FBCT (r = 0.69, p < 0.001). Macroscopic POD width was greater than all imaging modality (p < 0.001)., Main Limitations: Effect of motion artefact in live horse imaging could not be assessed., Conclusions: All imaging modalities were able to detect POD lesions, but underestimated lesion size. The CT systems were more sensitive, but the differing patterns of signal intensity may suggest that MRI can detect changes associated with POD pathological status or severity. The image features observed by CBCT and FBCT were similar., (© 2023 The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.)

Background: Dorsoproximal osteochondral defects commonly affect the proximal phalanx, but information about diagnosis on computed tomography (CT) and magnetic resonance imaging (MRI) is limited. Objectives: To assess CT and MRI diagnoses of osteochondral defects, describe the lesions and compare sensitivity and specificity of the modalities using macroscopic pathology as gold standard. Study design: Cross‐sectional study. Methods: Thirty‐five equine cadaver limbs underwent standing cone‐beam CT (CBCT), fan‐beam CT (FBCT), low‐field MRI and pathological examination. CT and MR images were examined for proximal phalanx dorsomedial and dorsolateral eminence osteochondral defects. Defect dimensions were measured. Imaging diagnoses and measurements were compared with macroscopic examination. Results: Fifty‐six defects were seen over 70 potential locations. On CBCT and FBCT, osteochondral defects appeared as subchondral irregularity/saucer‐shaped defects. On MRI, osteochondral defects were a combination of articular cartilage defect on dorsal images and subchondral flattening/irregularity on sagittal images. Subchondral thickening and osseous short tau inversion recovery hyperintensity were found concurrent with osteochondral defects. Compared with pathological examination, the sensitivity and specificity of diagnosis were 86% (95% confidence interval [95% CI] 75%–93%) and 64% (95% CI 38%–85%) for FBCT; 64% (95% CI 51%–76%) and 71% (95% CI 46%–90%) for CBCT; and 52% (95% CI 39%–65%) and 71% (95% CI 46%–90%) for MRI. Sensitivity of all modalities increased with defect size. Macroscopic defect dimensions were strongly correlated with CBCT (r = 0.76, p < 0.001) and moderately correlated with FBCT and MRI (r = 0.65, p < 0.001). Macroscopic measurements were significantly greater than all imaging modality dimensions (p < 0.001), potentially because macroscopy included articular cartilage pathology. Main limitations: Influence of motion artefact could not be assessed. Conclusions: Osteochondral defects could be visualised using both CT and MRI with sensitivity increasing with defect size. Diagnostic performance was best using FBCT, followed by CBCT then MRI, but CBCT‐measured defect size best correlated with macroscopic examination. MRI provided useful information on fluid signal associated with defects, which could represent active pathology. [ABSTRACT FROM AUTHOR]

Simple Summary: Fractures of the third metacarpal/tarsal parasagittal groove and proximal phalanx sagittal groove are common in racehorses. It is important to detect precursor pathologies including fissures to prevent the propagation to fracture. This study aims to identify the imaging features and compare the diagnosis of fissures on cone-beam (CB) computed tomography (CT), fan-beam (FB) CT, and low-field magnetic resonance imaging (MRI) to histopathology associated with fissures. Fissures were characterised on CBCT and FBCT as hypoattenuating linear defects, striated hypoattenuating lines, or subchondral irregularity. Fissures were characterised on MRI as subchondral hypo-/hyperintense defects. The diagnostic sensitivity was highest in CBCT, followed by FBCT and MRI, while specificity was highest in MRI, followed by FBCT and CBCT. Fissures identified on CT were associated with histopathology of subchondral bone sclerosis, microcracks, and collapse. In conclusion, all modalities were able to identify fissures with sensitivity higher in CT and specificity higher in MRI. CT-identified fissures were associated with histopathological indications of fatigue bone injuries. Imaging features and histopathological features of fissures characterised in this study may help clinical identification and image interpretation of fissures in horses. Fissure in the third metacarpal/tarsal parasagittal groove and proximal phalanx sagittal groove is a potential prodromal pathology of fracture; therefore, early identification and characterisation of fissures using non-invasive imaging could be of clinical value. Thirty-three equine cadaver limbs underwent standing cone-beam (CB) computed tomography (CT), fan-beam (FB) CT, low-field magnetic resonance imaging (MRI), and macro/histo-pathological examination. Imaging diagnoses of fissures were compared to microscopic examination. Imaging features of fissures were described. Histopathological findings were scored and compared between locations with and without fissures on CT. Microscopic examination identified 114/291 locations with fissures. The diagnostic sensitivity and specificity were 88.5% and 61.3% for CBCT, 84.1% and 72.3% for FBCT, and 43.6% and 85.2% for MRI. Four types of imaging features of fissures were characterised on CT: (1) CBCT/FBCT hypoattenuating linear defects, (2) CBCT/FBCT striated hypoattenuated lines, (3) CBCT/FBCT subchondral irregularity, and (4) CBCT striated hypoattenuating lines and FBCT subchondral irregularity. Fissures on MRI appeared as subchondral bone hypo-/hyperintense defects. Microscopic scores of subchondral bone sclerosis, microcracks, and collapse were significantly higher in locations with CT-identified fissures. All imaging modalities were able to identify fissures. Fissures identified on CT were associated with histopathology of fatigue injuries. [ABSTRACT FROM AUTHOR]

Summary Background Objective Study design Methods Results Main limitations Conclusions Cone‐beam computed tomography (CBCT) and low‐field magnetic resonance imaging (MRI) are increasingly used in standing horses, so it is important to understand an efficient application of these imaging modalities.To compare CBCT and MRI findings in the metacarpo (MCP)/metatarsophalangeal (MTP) region of clinical patients imaged for diagnostic purposes.Retrospective study.The CBCT and MRI images of the MCP/MTP region from equine clinical patients undergoing both standing MRI and CBCT imaging for lameness localised to the fetlock region (2021–2023) were retrospectively reviewed. Presence, location and imaging features of lesions were compared between modalities using descriptive analysis.Imaging studies of 24 MCP/MTP regions from 22 horses were included. CBCT provided the assessment of subchondral bone integrity in palmar/plantar osteochondral disease, details of the length and associated attenuation changes of third metacarpal/tarsal parasagittal groove and proximal phalanx sagittal groove fissures, structural integrity and attenuation changes of subchondral and trabecular bone injuries, proximal phalanx dorsoproximal defects and anatomical and structural details of proximal sesamoid bone injuries. MRI provided the evaluation of short tau inversion recovery (STIR) hyperintensity associated with bone lesions and the extent of increased fluid accumulation in bone. CBCT revealed reduced joint space, indicating articular cartilage loss, while MRI showed joint distension and synovitis. MRI revealed generalised osseous STIR hyperintensity associated with septic arthritis. Soft tissue injuries were most identified by MRI except for heterotopic mineralisation most detected by CBCT.Imaging findings not verified by a gold standard.CBCT and MRI contributed different diagnostic information so optimal information was obtained by using both modalities. Standing CBCT showed changes in bone structure and attenuation but was limited in detecting soft tissue injuries. Standing MRI showed increased fluid accumulation in bone and soft tissue injuries but was limited in assessing structural details of bone injuries. [ABSTRACT FROM AUTHOR]