Can Dual-Energy Computed Tomography Be Used to Identify Early Calcium Crystal Deposition in the Knees of Patients With Calcium Pyrophosphate Deposition?

Objective To assess the ability of dual-energy computed tomography (DECT) in identifying early calcium crystal deposition in menisci and articular cartilage of the knee, depending on the presence/absence of chondrocalcinosis seen on conventional CT. Methods One hundred thirty-two knee DECT scans from patients with suspected crystal-associated arthropathy were reviewed and assigned to a calcium pyrophosphate deposition (CPPD) group (n = 50) or a control group (n = 82). Five DECT attenuation parameters were measured in preset regions of interest (ROIs) in menisci and articular cartilage and compared between groups using linear mixed models with adjustment for confounders. Subgroup analysis, excluding ROIs with chondrocalcinosis seen on conventional CT, was performed. Results In both menisci and articular cartilage, and for all 5 DECT attenuation parameters, calcified ROIs in CPPD patients showed significantly higher values than ROIs in controls (P <= 0.036). Conversely, noncalcified ROIs in CPPD patients were comparable with those in controls (P >= 0.09). While specific DECT parameters yielded good accuracy (area under the curve [AUC] 0.87-0.88) in differentiating calcified ROIs in CPPD patients from ROIs in controls, DECT failed to distinguish between noncalcified ROIs in CPPD patients and controls (AUC 0.58-0.59). Conclusion While DECT has the potential to characterize knee intraarticular mineralization, this technique cannot yet accurately identify early calcium crystal deposition that is not visible as chondrocalcinosis on conventional CT.