A rapid, novel method of volumetric assessment of MRI-detected subchondral bone marrow lesions in knee osteoarthritis

Abstract

Purpose: To assess reliability and validity of a semi-automated quantitative method for osteoarthritis (OA)-related bone marrow lesion (BML) assessment in the femur and tibia.

Methods: In a cross-sectional study of subjects with knee OA, we examined concurrent criterion and clinical validation of a novel method of semi-automated quantitative BML measurement. The primary outcome was total segmented BML volume in femoral and tibial medial and lateral knee compartments. Criterion validation was examined through comparison of BML volumes with Whole-Organ Magnetic Resonance Imaging Score (WORMS) scoring. Clinical validation was examined via associations of tibial and femoral BML volume with the Western Ontario and McMaster University OA Index weight-bearing pain questions.

Results: Among the 115 subjects, mean age was 62 years, mean BMI 30.4 (kg/m(2)), 84% were white and 52% male. The intra-class correlation coefficients (ICC) for intra-reader reliability was 0.96 and 0.97 for inter-reader reliability. Significant Spearman's correlations were found between segmented BML volume and WORMS BML scoring for tibial medial (0.75) and lateral (0.73) compartments, and for femoral medial (0.72) and lateral (0.88) compartments. Significant positive associations were found between weight-bearing pain and total femoral BML volume (P < 0.003), but not total tibial BML (P < 0.101).

Conclusion: We have documented a moderately strong correlation between a novel measurement method of femoral and tibial BML volume and semi-quantitative WORMS scores, providing evidence of criterion validity. The hypothesis that weight-bearing pain was associated with BML volume was confirmed for total femoral BML volume but not total tibial BML volume. The lack of association between tibial BML volume and pain requires further investigation.

Causes of subchondral signal alterations of the knee joint, not due to osteoarthritis

(a) Subchondral Insufficiency Fracture - Sagittal IW fat-suppressed MRI shows a subtle subchondral irregular hypointense line (arrowheads) of the medial femoral condyle which represents subchondral insufficiency fracture surrounded by an extensive hyperintensity bone marrow edema (arrows). Also there is a large heterogeneous hyperintensity of the medial tibial plateau (thin arrows) typical for osteoporosis in this 59-year-old woman. Note there is a small joint effusion. (b) Traumatic Bone Marrow Secondary to Transient Lateral Subluxation of the Patella - Sagittal IW fat-suppressed MRI shows moderate hyperintensity of the lateral femoral condyle (arrows) distant from the subchondal bone and typical for traumatic bone marrow secondary to transient lateral subluxation of the patella. Note there is also a grade 1 medial collateral ligament sprain

Causes of subchondral signal alterations of the knee joint, not due to osteoarthritis

(a) Subchondral Insufficiency Fracture - Sagittal IW fat-suppressed MRI shows a subtle subchondral irregular hypointense line (arrowheads) of the medial femoral condyle which represents subchondral insufficiency fracture surrounded by an extensive hyperintensity bone marrow edema (arrows). Also there is a large heterogeneous hyperintensity of the medial tibial plateau (thin arrows) typical for osteoporosis in this 59-year-old woman. Note there is a small joint effusion. (b) Traumatic Bone Marrow Secondary to Transient Lateral Subluxation of the Patella - Sagittal IW fat-suppressed MRI shows moderate hyperintensity of the lateral femoral condyle (arrows) distant from the subchondal bone and typical for traumatic bone marrow secondary to transient lateral subluxation of the patella. Note there is also a grade 1 medial collateral ligament sprain

Figure 1. BML semi-automated segmentation. (a) software presents hyperintense areas in green based on gray-scale thresholding, (b) reader selects areas of subchondral OA related BML-green changes to red (2 mouse clicks in this case), (c) appearance of final segmented BML

Figure 2. Box and whisker plots showing mean, median, lower and upper quartiles, and outliers of BML volume from semi-automated quantitative assessment, by WORMS scores, for femoral (a) lateral compartment, and (b) medial compartment

Figure 3. Box and whisker plots showing mean, median, lower and upper quartiles, and outliers of BML volume from semi-automated quantitative assessment, by WORMS scores, for tibial (a) lateral compartment, and (b) medial compartment