Optimal sampling of MRI slices for the assessment of knee cartilage volume for cross-sectional and longitudinal studies

The accuracy of MRI in diagnosing and classifying acute traumatic multiple ligament knee injuries

Background

Magnetic resonance imaging (MRI) is widely used for the evaluation of knee injuries, however, the accuracy of MRI in classifying multiple ligament knee injuries (MLKIs) remains unknown. This study aimed to investigate the accuracy of MRI in diagnosing and classifying acute traumatic MLKIs, we hypothesize that MRI had high accuracy in detecting and classifying MLKIs.

Methods

The clinical data of 97 patients who were diagnosed with acute traumatic MLKIs and managed by multi-ligament reconstruction between 2012 and 2020 were retrospectively reviewed. The MR images were read by two experienced radiologists and results were compared with intraoperative findings, which were considered as the reference for the identification of injured structures. The value of MRI in detecting injuries of anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), lateral collateral ligament (LCL), and meniscus was evaluated by calculating the sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio, and kappa coefficients analysis. The value of MRI in classifying MLKIs was evaluated by calculating the agreement between MRI and intraoperative findings.

Results

For detecting the specific injured structures in MLKIs, MRI had high sensitivity (90.7% for ACL, 90.4% for PCL, and moderate specificity (63.6% for ACL, 50% for PCL) in detecting cruciate ligament injuries, moderate sensitivity (79.1% for MCL, 55.6% for LCL) and specificity (46.7% for MCL, 68.4% for LCL) in detecting collateral ligament injuries, fair sensitivity (61.5%) and low specificity (39.4%) in the diagnosis of injuries to the meniscus. For classifying the MIKIs, MRI had a moderate agreement with intraoperative findings in classifying KD-V (kappa value = 0.57), poor agreement in the KD-I (kappa value = 0.39) and KD-IIIM (kappa value = 0.31), meaningless in the KD-II and KD-IIIL (kappa value < 0). The overall agreement between MRI and intraoperative findings in classifying MLKIs was poor (kappa value = 0.23).

Conclusions

MRI is valuable in early detection and diagnosis of acute MLKIs, however, the accuracy of MRI in classifying MLKIs is limited. The management of MLKIs should be based on intraoperative findings, physical examinations, and comprehensive imaging results.

Equivalence and precision of knee cartilage morphometry between different segmentation teams, cartilage regions, and MR acquisitions

OBJECTIVE

To compare precision and evaluate equivalence of femorotibial cartilage volume (VC) and mean cartilage thickness over total area of bone (ThCtAB.Me) from independent segmentation teams using identical Magnetic Resonance (MR) images from three series: sagittal 3D Dual Echo in the Steady State (DESS), coronal multi-planar reformat (DESS-MPR) of DESS and coronal 3D Fast Low Angle SHot (FLASH).

DESIGN

Nineteen subjects underwent test-retest MR imaging at 3 T. Four teams segmented the cartilage using prospectively defined plate regions and rules. Mixed models analysis of the pooled data were used to evaluate the effect of acquisition, team and plate on precision and Pearson correlations and mixed models were used to evaluate equivalence.

RESULTS

Segmentation team differences dominated measurement variability in most cartilage regions for all image series. Precision of VC and ThCtAB.Me differed significantly by team and cartilage plate, but not between FLASH and DESS. Mean values of VC and ThCtAB.Me differed by team (P < 0.05) for DESS, FLASH and DESS-MPR. FLASH VC was 4-6% larger than DESS in the medial tibia and lateral central femur, and FLASH ThCtAB.Me was 5-6% larger in the medial tibia, but 4-8% smaller in the medial central femur. Correlations between DESS and FLASH for VC and ThCtAB.Me were high (r = 0.90-0.97), except for DESS vs FLASH medial central femur ThCtAB.Me (r = 0.81-0.83).

CONCLUSIONS

Cartilage morphology metrics from different image contrasts had similar precision, were generally equivalent, and may be combined for cross-sectional analyses if potential systematic offsets are accounted for. Data from different teams should not be pooled unless equivalence is demonstrated for cartilage metrics of interest.

Responsiveness and reliability of MRI in knee osteoarthritis: a meta-analysis of published evidence

OBJECTIVE

To summarize literature on the responsiveness and reliability of MRI-based measures of knee osteoarthritis (OA) structural change.

METHODS

A literature search was conducted using articles published up to the time of the search, April 2009. 1338 abstracts obtained with this search were preliminarily screened for relevance and of these, 243 were selected for data extraction. For this analysis we extracted data on reliability and responsiveness for every reported synovial joint tissue as it relates to MRI measurement in knee OA. Reliability was defined by inter- and intra-reader intra-class correlation (ICC), or coefficient of variation, or kappa statistics. Responsiveness was defined as standardized response mean (SRM) - ratio of mean of change over time divided by standard deviation of change. Random-effects models were used to pool data from multiple studies.

RESULTS

The reliability analysis included data from 84 manuscripts. The inter-reader and intra-reader ICC were excellent (range 0.8-0.94) and the inter-reader and intra-reader kappa values for quantitative and semi-quantitative measures were all moderate to excellent (range 0.52-0.88). The lowest value (kappa=0.52) corresponded to semi-quantitative synovial scoring intra-reader reliability and the highest value (ICC=0.94) for semi-quantitative cartilage morphology. The responsiveness analysis included data from 42 manuscripts. The pooled SRM for quantitative measures of cartilage morphometry for the medial tibiofemoral joint was -0.86 (95% confidence intervals (CI) -1.26 to -0.46). The pooled SRM for the semi-quantitative measurement of cartilage morphology for the medial tibiofemoral joint was 0.55 (95% CI 0.47-0.64). For the quantitative analysis, SRMs are negative because the quantitative value, indicating a loss of cartilage, goes down. For the semi-quantitative analysis, SRMs indicating a loss in cartilage are positive (increase in score).

CONCLUSION

MRI has evolved substantially over the last decade and its strengths include the ability to visualize individual tissue pathologies, which can be measured reliably and with good responsiveness using both quantitative and semi-quantitative techniques.

Non-invasive in vivo quantification of the medial tibial cartilage thickness progression in an osteoarthritis rabbit model with quantitative 3D high resolution micro-MRI

OBJECTIVE

To develop a quantitative non-invasive in vivo three-dimensional (3D) high resolution (HR) micro-magnetic resonance imaging (microMRI) protocol to measure the medial tibial cartilage thickness (MT.ThC) in the normal rabbit and in the anterior cruciate ligament transection (ACLT) rabbit model of osteoarthritis and quantify the progression of MT.ThC.

METHODS

The left knee of 10 control and 40 operated rabbits was imaged in vivo with a 7T microMRI system at 3 and 5 months after ACLT. A 3D fast low angle short (FLASH) fat-suppressed MRI protocol was implemented leading to 44x176 microm(3) spatial resolution and to 44 microm(3) isotropic voxel after cubic interpolation. Semi-automatic MT.ThC measurements were made in 3D, in four different locations, in vivo and longitudinally in both groups. At 5 months, gross macroscopy, visual analogical evaluation of the cartilage and histology were compared to the MR-based MT.ThC.

RESULTS

At 3 and 5 months, the MT.ThC measured in the minimum interbone distance area was the thinnest MR-based MT.ThC. It was significantly lower in the operated group and among the four evaluated MT.ThC, it was the most discriminative between the normal and the operated groups (P<0.05). The MT.ThC measured in the minimum interbone distance area was also the most sensitive to change in the operated group (66.4% MT.ThC loss, P=0.003) while no significant changes were observed in the control group.

CONCLUSION

Quantitative 3D HR microMRI allowed for non-invasive longitudinal MT.ThC measurements in four different locations in both the normal and the operated rabbits. We concluded the MT.ThC measured in the minimum interbone distance area reflected the severity of the disease and was the most effective to measure the progression of the medial tibial cartilage destruction.

Quantitative MRI of cartilage and bone: degenerative changes in osteoarthritis

Magnetic resonance imaging (MRI) and quantitative image analysis technology has recently started to generate a great wealth of quantitative information on articular cartilage and bone physiology, pathophysiology and degenerative changes in osteoarthritis. This paper reviews semiquantitative scoring of changes of articular tissues (e.g. WORMS = whole-organ MRI scoring or KOSS = knee osteoarthritis scoring system), quantification of cartilage morphology (e.g. volume and thickness), quantitative measurements of cartilage composition (e.g. T2, T1rho, T1Gd = dGEMRIC index) and quantitative measurement of bone structure (e.g. app. BV/TV, app. TbTh, app. Tb.N, app. Tb.Sp) in osteoarthritis. For each of these fields we describe the hardware and MRI sequences available, the image analysis systems and techniques used to derive semiquantitative and quantitative parameters, the technical accuracy and precision of the measurements reported to date and current results from cross-sectional and longitudinal studies in osteoarthritis. Moreover, the paper summarizes studies that have compared MRI-based measurements with radiography and discusses future perspectives of quantitative MRI in osteoarthritis. In summary, the above methodologies show great promise for elucidating the pathophysiology of various tissues and identifying risk factors of osteoarthritis, for developing structure modifying drugs (DMOADs) and for combating osteoarthritis with new and better therapy.

Magnetic resonance imaging (MRI) of articular cartilage in knee osteoarthritis (OA): morphological assessment

OBJECTIVE

Magnetic resonance imaging (MRI) is a three-dimensional imaging technique with unparalleled ability to evaluate articular cartilage. This report reviews the current status of morphological assessment of cartilage with quantitative MRI (qMRI), and its relevance for identifying disease status, and monitoring progression and treatment response in knee osteoarthritis (OA).

METHOD

An international panel of experts in MRI of knee OA, with direct experience in the analysis of cartilage morphology with qMRI, reviewed the existing published and unpublished data on the subject, and debated the findings at the OMERACT-OARSI Workshop on Imaging technologies (December 2002, Bethesda, MA) with scientists and clinicians from academia, the pharmaceutical industry and the regulatory agencies. This report reviews (1) MRI pulse sequence considerations for morphological analysis of articular cartilage; (2) techniques for segmenting cartilage; (3) semi-quantitative scoring of cartilage status; and (4) technical validity (accuracy), precision (reproducibility) and sensitivity to change of quantitative measures of cartilage morphology.

RESULTS

Semi-quantitative scores of cartilage status have been shown to display adequate reliability, specificity and sensitivity, and to detect lesion progression at reasonable observation periods (1-2 years). Quantitative assessment of cartilage morphology (qMRI), with fat-suppressed gradient echo sequences, and appropriate image analysis techniques, displays high accuracy and adequate precision (e.g., root-mean-square standard deviation medial tibia=61 microl) for cross-sectional and longitudinal studies in OA patients. Longitudinal studies suggest that changes of cartilage volume of the order of -4% to -6% occur per annum in OA in most knee compartments (e.g., -90 microl in medial tibia). Annual changes in cartilage volume exceed the precision errors and appear to be associated with clinical symptoms as well as with time to knee arthroplasty.

CONCLUSIONS

MRI provides reliable and quantitative data on cartilage status throughout most compartments of the knee, with robust acquisition protocols for multi-center trials now being available. MRI of cartilage has tremendous potential for large scale epidemiological studies of OA progression, and for clinical trials of treatment response to structure modifying OA drugs.