Dual-energy CT for detection of traumatic bone bruises in the knee joint

To evaluate the diagnostic performance of dual-energy computed tomography (DECT) in detecting traumatic bone marrow lesions in patients with acute knee injury. Between August 2011 and June 2012, 22 patients presenting with an acute knee injury, including 4 patients who were referred for bilateral knee trauma, underwent DECT (80 kVp and 140 kVp) and MR imaging. DECT data were postprocessed using a three-dimensional, color-coded, virtual non-calcium technique (VNC). DECT data were graded by 2 blinded independent readers using a four-point system (1 = distinct bone marrow lesion, 2 = less distinct bone marrow lesion, 3 = equivocal, 4 = none) for 6 femoral and tibial regions and 2 patellar regions. Routine MR knee imaging served as the reference standard. MR images showed bone bruises in 81 of 364 regions. The overall sensitivity, specificity, positive predictive value, and negative predictive value of DECT for bone bruises were 65.4%, 98.2%, 91.4%, and 90.8%, respectively, for Reader 1 and 70.3%, 93.6%, 76.0%, and 91.7%, respectively, for Reader 2. In particular, tibial bone bruises could be found more easily with better sensitivity (80.2%). The color-coded VNC technique with reconstructions from the DECT maybe helpful in detecting traumatic bone bruises with moderate sensitivity and excellent specificity compared to MR imaging.