Improved accuracy of bone marrow edema detection in patients with hip pain using dual-energy computed tomography: Optimization of blended material density images combining water-calcium and water-hydroxyapatite

Rationale and Objectives: This study aimed to optimize newly developed blended material density (MD) images, compare them with conventional water-calcium (Ca) and water-hydroxyapatite (HAP) images, and identify the most suitable MD images for detecting bone marrow edema (BME). Materials and Methods: We retrospectively analyzed the data of 24 patients (47 hips) who underwent dual-energy computed tomography (DECT) and magnetic resonance imaging (MRI) within one week of experiencing hip pain between April 2022 and March 2024. DECT was performed using a single-source fast-kV switching system and two material decomposition algorithms to generate 9 blended MD images by adjusting the mixing ratios of waterCa and water-HAP (water-9Ca:1HAP to water-1Ca:9HAP). The optimal blended MD image was identified using the area under the curve (AUC) from the receiver operating characteristic (ROC) analysis. Radiologists and orthopedic surgeons visually assessed the concordance between the three types of MD images and MRI findings using a five-point scale. Results: Among the 24 patients, 19 (79.2 %) were diagnosed with BME through MRI. Among the blended MD images, water-2Ca:8HAP demonstrated the highest diagnostic accuracy (AUC: 0.980), significantly outperforming water-Ca (AUC: 0.909, P <0.01) and water-HAP (AUC: 0.898, P = 0.01). At a cut-off value of 969 mg/cm(3), water-2Ca:8HAP achieved a sensitivity of 100.0 % and specificity of 91.8 %. Visual assessments further confirmed the highest concordance with MRI findings (both P < 0.01). Conclusion: The blended MD image using water-2Ca:8HAP demonstrated superior diagnostic performance compared to conventional images, offering a promising tool for improved BME detection.