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Background: Revisions of hip prostheses are increasing, and conventional radiography (CR) is a primary tool for managing complications. However, dual-energy CT (DECT) with virtual monoenergetic imaging is capable of reducing periprosthetic metal artifacts compared with standard CT.Purpose: To compare the diagnostic performance of DECT and CR in detecting hip prosthesis loosening, using surgery as a reference for diagnosis. Materials and Methods:This retrospective single-center study conducted between January 2018 and October 2020 included consecutive patients with unilateral painful hip prostheses. Two independent readers (with 15 years and 4 years of experience) who were blinded to clinical findings evaluated CR and DECT images. At imaging, diagnosis of loosening prosthesis was made for periprosthetic radiolucency greater than or equal to 2 mm wide or the presence of two or more secondary findings, including periprosthetic osteolysis, angulation of the implant, fracture, or abnormal periosteal reaction. For each reader and for each imaging parameter, sensitivity and specificity were calculated. The diagnostic performance of each imaging tool was compared by using the McNemar test. Interobserver agreements were calculated with Cohen κ statistics. Statistical software was used.Results: Overall, 178 patients (mean age ± standard deviation, 74 years ± 20; 96 men) were included (121 undergoing surgery, 57 follow-up). Overall, 87 of 178 patients (49%) were diagnosed with a loosened prosthesis. DECT had higher sensitivity and specificity than CR for both reader 1

Objectives To evaluate the diagnostic accuracy of venous-phase dual-energy computed tomography (VP-DECT) in the identification of PE compared with standard CT pulmonary angiography (CTPA). Methods This prospective IRB-approved study included 61 consecutive oncology patients (35 females, 26 males, mean age 66.91 years) examined by CTPA and VP-DECT. DECT data were post-processed on a SyngoVia workstation to obtain monoenergetic images (MEI+). The diagnosis of PE was based on the presence of any vascular perfusion defects. DECT images were evaluated independently by two radiologists (8 and 16 years of experience). A consensus reading of CTPA images (two senior radiologists, 18 and 24 years of experience) represented the reference for diagnosis. The diagnostic accuracy values of VP-DECT on a per-patient and per-lobe basis were assessed. Interobserver agreement was calculated using k-statistics. A value of p < 0.05 was considered statistically significant. Results Thirty of 61 patients (49.18%) were diagnosed with PE by CTPA, with 57/366 lobes being involved (15.57%). The sensitivity and specificity of the per-patient analysis of VP-DECT images were 90.0% (27/30) and 100% (31/31) respectively, for both readers. As concerns the per-lobe analysis, the sensitivity ranged from 100% for the right lower lobe to 50% for the left upper lobe for reader 1, and from 100% for the left upper lobe to 69.23% for the lingula for reader 2. The interobserver agreement ranged from 0.8671 (patients' analysis) to 0.6419 (lobes' analysis). Conclusion VP-DECT could be considered an accurate imaging tool for diagnosing PE in a selected, high-prevalence population, compared with CTPA. Key Points • With regard to the patients' analysis, venous-phase DECT sensitivity and specificity in diagnosing pulmonary embolism were 90% and 100%, respectively, for both readers.• With regard to the lobes' analysis, the sensitivity ranged from 100 to 50%, for reader 1, and from 100 to 69.23%, for reader 2, respectively. • The sensitivity and specificity of lung perfusion maps obtained from venous DECT were 73.33% and 67.74% as concerns the patients' analysis and 71.92% and 75.72% as regards the lobes' analysis, respectively.

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