EFFECTS OF OBSERVER ON THE DIAGNOSTIC ACCURACY OF LOW‐FIELD MRI FOR DETECTING CANINE MENISCAL TEARS

Abstract

Low-field MRI (lfMRI) has become increasingly accepted as a method for diagnosing canine meniscal tears in clinical practice. However, observer effects on diagnostic accuracy have not been previously reported. In this study, 50 consecutive stifle joints with clinical and radiologic evidence of cranial cruciate ligament insufficiency were investigated by lfMRI and arthroscopy. Fifteen observers who had varying levels of experience and who were unaware of arthroscopic findings independently reviewed lfMRI studies and recorded whether lateral and medial meniscal tears were present. Diagnostic accuracy (sensitivity, specificity, positive (PPV) and negative predictive value (NPV)) was determined for each observer and median values were calculated for all observers, using arthroscopy as the reference standard. Interrater agreement was determined based on intraclass correlation coefficient (ICC) analysis. Observer level of experience was compared with diagnostic sensitivity and specificity using correlation analysis. Based on pooled data for all observers, median sensitivity, specificity, PPV, and NPV for lfMRI diagnosis of lateral meniscal tears were 0.00, 0.94, 0.05, and 0.94, respectively. Median sensitivity, specificity, PPV, and NPV for medial meniscal tears were 0.74, 0.89, 0.83, and 0.79, respectively. Interrater agreement for all menisci was fair (0.51). Menisci were less consistently scored as having no tears (ICC = 0.13) than those scored as having tears (ICC = 0.50). No significant correlations between observer experience and diagnostic sensitivity/specificity were identified. Findings indicated that the accuracy of lfMRI for diagnosing canine meniscal tears was poor to fair and observer-dependent. Future studies are needed to develop standardized and widely accepted lfMRI criteria for diagnosing meniscal tears.

Assessment of the usefulness of image reconstruction in the oblique and double-oblique sagittal planes for magnetic resonance imaging of the canine cranial cruciate ligament

“…The values of the angles differed considerably. The values of angles α were similar to those used by Böttcher et al (5) assuming 5° and 10°, respectively. No information was found in the available literature on the effect of a double-oblique cross-sectional plane on CCL imaging in dogs, so it was impossible to compare the value of the angle β with the results of other studies.…”

“…In the available literature, the authors used different coils depending on their device and test assumptions. Most often, these were rigid or flexible organ coils dedicated to limb imaging and included elbow (37), carpal (2), knee (5,32,40,43), and spinal (4) varieties, which were also solenoidal (44) or dual-phased array coils (8,15,46). The selection for this study of a dualphased array knee coil allowed for better image quality due to the higher SNR.…”

“…Currently, apart from the manufacturer's instructions, there are no guidelines regarding the positioning of the dog for knee imaging. In other articles, dogs were placed in the dorsal (2,5,12,23,24,32,40,43,44) lateral (4,11,36,37) or bridge position (15).…”

Effects of Stifle Flexion Angle and Scan Plane on Visibility of the Normal Canine Cranial Cruciate Ligament Using Low‐field Magnetic Resonance Imaging

“…A series of FSE T2‐weighted sequences were acquired in eight different planes for each of the stifle angles. Previous reports in veterinary medicine used either the patellar ligament or the tibial plateau as the anatomical landmark to plan the dorsal and axial planes . Because we were interested in the effect of stifle angle on the visibility of the cranial cruciate ligament regardless of the landmark used for planning, we decided to include scans based on both anatomical landmarks.…”

The Use of Small Field‐of‐view 3 Tesla Magnetic Resonance Imaging for Identification of Articular Cartilage Defects in the Canine Stifle: An Ex Vivo Cadaveric Study

“…To date, a modest number of reports have described the use of MRI for evaluation of articular cartilage in dogs. The majority of these reports use low field magnets and subjective image evaluation . Recent work in humans has led to the development of quantitative measures of cartilage degradation using MRI .…”