Identification of bone marrow edema of the knee: diagnostic accuracy of dual-energy CT in comparison with MRI

Background To assess the diagnostic accuracy of dual-energy computed tomography (DECT) in diagnosing bone marrow edema (BME) of the knee in traumatic and non-traumatic patients. Methods This prospective IRB approved study included 33 consecutive patients (20 males, 13 females; mean age of 52.2 years) evaluated with DECT (80 and 150 kV) and MRI within 6 days. Two experienced radiologists qualitatively and quantitatively evaluated DECT images. The accuracy values were calculated by using receiver operator curves (ROC) and area under the curve (AUC), using MRI as the reference standard. Inter-observer and intra-observer agreement were calculated with k -statistics. A p < 0.05 was considered statistically significant. Results MRI depicted BME in 25/33 patients (75.7%). The sensitivity, specificity, PPV, NPV, and accuracy of per-partition qualitative analysis were 92.9, 92.9, 78.2, 97.9, and 92.9%, for reader 1, and 88.2, 93.9, 79.8, 96.6, and 92.6%, for reader 2, respectively. The inter-observer agreement was substantial ( k = 0.793) and the intra-observer agreement was near-perfect ( k = 0.844). At the quantitative analysis, a significant difference ( p < 0.001) was depicted between the density values of positive (mean 3.6 ± 25.3 HU) and negative cases (mean − 72.2 ± 45.1 HU). By using − 15 HU cutoff to identify BME, sensitivity, specificity, PPV, NPV, and accuracy of DECT were 84.7, 93.6, 78.2, 95.7, and 91.6%, respectively. Conclusion DECT can accurately identify BME of the knee.