Clinical magnetic resonance image quality of the equine foot is significantly influenced by acquisition system

Abstract

Background Investigation of image quality in clinical equine magnetic resonance (MR) imaging may optimise diagnostic value. Objectives To assess the influence of field strength and anaesthesia on image quality in MR imaging of the equine foot in a clinical context. Study design Analytical clinical study. Methods Fifteen equine foot studies (five studies per system) were randomly selected from the clinical databases of three MR imaging systems: low‐field standing (LF St), low‐field anaesthetised (LF GA) and high‐field anaesthetised (HF GA). Ten experienced observers graded image quality for entire studies and seven clinically important anatomical structures within the foot (briefly, grade 1: textbook quality, grade 2: high diagnostic quality, grade 3: satisfactory diagnostic quality, grade 4: non‐diagnostic). Statistical analysis assessed the effect of anaesthesia and field strength using a combination of the Pearson chi‐square test or Fisher’s exact test and Mann‐Whitney test. Results There was no difference in the proportion of entire studies of diagnostic quality between LF St (90%, 95% CI 78%‐97%) and LF GA (88%, 76‐95%, P = .7). No differences were evident in the proportion of diagnostic studies or median image quality gradings between LF St and LF GA when assessing individual anatomical structures (both groups all median grades = 3). There was a statistically significant difference in the proportion of entire studies of diagnostic quality between LF GA and HF GA (100%, 95% CI lower bound 94%, P = .03). There were statistically significant differences in median image quality gradings between LF GA (all median grades = 3) and HF GA (median grades = 1 (5/7 structures) or 2 (2/7 structures) for all individual anatomical structures (all P < .001). The reasons reported for reduced image quality differed between systems. Main limitations Randomised selection of cases from clinical databases. Individual observer preferences may influence image quality assessment. Conclusions Field strength is a more important influencer of image quality than anaesthesia for magnetic resonance imaging of the equine foot in clinical patients.

Assessment of Magnetic Resonance Imaging Artefacts Caused by Equine Anaesthesia Equipment: A Cadaver Study

“…Nonetheless, scoring was performed by a specialist veterinary radiologist with extensive experience specifically in equine imaging, who was unaware of group assignment. The presence of artefacts was also graded utilising a subjective scoring system adapted from a previously published scoring system [3], and detailed definitions were provided for each grade. Thirdly, some other factors possibly affecting scan quality were not fully controlled or recorded, such as temperature and activity in adjacent rooms.…”

“…Advantages are particularly evident when investigating lameness that affects the equine foot, where the hoof capsule limits the diagnostic value of conventional imaging modalities [2,3]. In addition, when compared to computed tomography (CT), low-field MRI systems (LFMRI) have been shown to produce higher anatomic visualisation scores of structures like the distal sesamoidean impar ligament, synovial structures, and the distal deep flexor tendon (DDFT) [4].…”

“…Equine MRI is commonly conducted in the standing horse to avoid the potential risks of general anaesthesia [2,6]. However, patients are sometimes anaesthetised for acquisition of images, particularly for regions proximal to the foot (more susceptible to pendulous sway motion) in order to reduce movement artefacts [1,3]. Anaesthesia of the equine patient for MRI presents multiple challenges, some of which are specifically related to this imaging modality.…”

When radiography and ultrasonography are not enough: the use of computed tomography and magnetic resonance imaging for equine lameness cases

“…14,15 Higher magnet strength has several clinically relevant advantages, including decreased scan times, increased resolution, larger field of view, availability of specialized sequences (eg, to evaluate articular cartilage), and overall improved image quality. 5,[16][17][18] These factors can translate into increased anatomic visibility, greater diagnostic ability, and higher diagnostic confidence in the findings. [18][19][20] One recent study 17 comparing low-field standing, low-field general anesthesia, and high-field general anesthesia MRI examinations of the equine foot found that image quality was better in high-field scans than in either type of low-field scan, indicating that higher field strength itself led to improved image quality rather than the use of general anesthesia.…”

“…5,[16][17][18] These factors can translate into increased anatomic visibility, greater diagnostic ability, and higher diagnostic confidence in the findings. [18][19][20] One recent study 17 comparing low-field standing, low-field general anesthesia, and high-field general anesthesia MRI examinations of the equine foot found that image quality was better in high-field scans than in either type of low-field scan, indicating that higher field strength itself led to improved image quality rather than the use of general anesthesia. Other studies 18,[21][22][23][24] have shown higher detail and/or greater lesion detection in a variety of tissue types with high-field MRI than with low-field MRI in the foot, fetlock region, proximal metacarpus, and carpus.…”