T1 ρ and T2 mapping for the determination of articular cartilage denaturalization with osteonecrosis of the femoral head: A prospective controlled trial.

BACKGROUND

In the future, biochemical MRI might provide a valuable noninvasive quantitative analysis of the biochemical composition of cartilage in osteonecrosis of the femoral head (ONFH).

PURPOSE: To investigate the diagnostic performance of T1 ρ and T2 mapping in cartilage denaturalization with ONFH and to determine the correlation between T1 ρ and T2 mapping and the Association Research Circulation Osseous (ARCO) stage.

STUDY TYPE: Prospective.

SUBJECTS: Forty-seven patients with ONFH (stage I to III according to the ARCO criteria) and 24 volunteers (control group) were recruited for the prospective study.

SEQUENCE: Conventional MRI, multiple echo recalled gradient echo (MERGE), and T1 ρ and T2 mapping sequences.

ASSESSMENT: Pseudocolor images and MERGE images were combined in the AW4.5 workstation. The region of interest (ROI) of the hip cartilage was 4-6 mm². The sagittal T1 ρ and T2 mapping values were calculated by the two first authors.

STATISTICAL TESTS: One-way analysis of variance (ANOVA), LSD t-tests, Pearson correlation analysis, and receiver operator characteristic (ROC) curves. The significance level was set at P < 0.05.

RESULTS

The T1 ρ and T2 mapping values of the ONFH group were significantly higher than the values of the control group (P = 0.000). Regarding the assessment of the severity of ARCO staging, both T1 ρ (r = 0.66, P = 0.004) and T2 mapping (r = 0.501, P = 0.002) were positively associated with disease severity. The T1 ρ values were positively correlated with the T2 mapping values (r = 0.381, P = 0.000). The areas under the curve (AUC) for the T1 ρ and T2 mapping values were 0.822 and 0.791, respectively. The diagnostic sensitivity and specificity were 72.34% and 70.83% for T1 ρ mapping and 72.34% and 58.33%, respectively, for T2 mapping.

DATA

CONCLUSION

Both T1 ρ and T2 mapping performed well in diagnosing the cartilage denaturalization in ARCO stage I-III ONFH patients. T1 ρ mapping had a higher diagnostic sensitivity and specificity than T2 mapping.

LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:760-767.