Dual-Energy CT for Detection of Traumatic Bone Bruises in the Knee Joint

Abstract

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. This paper was supported by Wonkwang university in 2012.Purpose: To evaluate the diagnostic performance of dual-energy computed tomography (DECT) in detecting traumatic bone marrow lesions in patients with acute knee injury. Materials and Methods: 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. Results: 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%). Conclusion: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.

Good interrater reliability of a new grading system in detecting traumatic bone marrow lesions in the knee by dual energy CT virtual non-calcium images

“…The difference in CT value of the bone marrow between the BMLpositive and BML-negative areas is the main factor influencing the results of VNCa image diagnosis [14][15][16]. In our study, this difference was significant, which allowed the BMLs to be found on VNCa images.…”

“…If this value was not suitable, the calcium residue or the false negative BMLs will present on VNCa images. The Rel.CM value set to 1.45 is suitable in dual energy subtraction of calcium for firstgeneration dual-source CT, which has been affirmed in previous studies [14,15]. For efficient evaluation of BMLs, we used multiplanar reformation images with the adjusted windows setting and carefully measured the CT value of the bone marrow.…”

“…Wang [19] and Bierry et al [20] also applied the VNCa technique in patients with spinal fracture, and showed that VNCa images can be used to detect bone marrow abnormalities after vertebral fractures. Pache [14] and Seo et al [15] used VNCa images to detect post-traumatic bone marrow abnormalities using a four-grading system in patients without obvious bone fracture in the knee joint and both obtained satisfactory results. However, these studies all did not evaluation the consistency of grading of traumatic BMLs between VNCa and MR images.…”

“…First, it involves relatively high-dose X-ray radiation [14][15][16], which needs to be properly reduced during clinical application. Second, since the first-generation dual-source CT has relatively small field of view in dual-energy imaging, it is sometimes difficult to include both knee joints simultaneously.…”

“…Virtual non-calcium (VNCa) image of the bone joint can display the bone marrow by means of subtracting of calcium using dual-energy algorithm [14][15][16][17]. Because of edema and hemorrhage after trauma, bone marrow has an increased CT value with higher density compared to normal bone marrow.…”