Diagnostic Performance of Dual-Energy CT for Detecting Painful Hip Prosthesis Loosening.

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 (94% [82 of 87 examinations; 95% CI: 87, 98] and 93% [85 of 91 examinations; 95% CI: 86, 97] vs 84% [73 of 87 examinations; 95% CI: 74, 91] and 91% [83 of 91 examinations; 95% CI: 83, 96], respectively; P < .001) and reader 2 (92% [80 of 87 examinations; 95% CI: 84, 97] and 95% [86 of 91 examinations; 95% CI: 88, 98] vs 80% [70 of 87 -examinations; 95% CI: 71, 88] and 91% [83 of 91 examinations; 95% CI: 83, 96], respectively; P = .001), with better interobserver agreement (κ, 0.88 [95% CI: 0.81, 0.95] vs 0.78 [95% CI: 0.69, 0.88]). Conclusion Dual-energy CT showed better diagnostic performance than conventional radiography in diagnosing hip prosthesis loosening. See also the editorial by Lutz in this issue. © RSNA, 2021.

Identification of pulmonary embolism: diagnostic accuracy of venous-phase dual-energy CT in comparison to pulmonary arteries CT angiography.

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.

Identification of bone marrow edema around the ankle joint in non-traumatic patients: Diagnostic accuracy of dual-energy computed tomography.

OBJECTIVES: To evaluate the diagnostic accuracy of DECT in the identification of BME of the ankle in non-traumatic patients. METHODS: This prospective institutional review board approved study included 40 consecutive patients (21 males and 19 females, mean age 56.8 years, SD = 11.37) that were examined using DECT and MRI in the period between April 2019 and January 2020. Two radiologists (7 and 16 years of experience) evaluated the presence of BME on DECT mages. Diagnostic accuracy values for diagnosing BME on a per-patient and on a per-partition basis analysis were calculated for DECT images by two readers (R1 and R2, with 16 and 7 years of experience, respectively), using MRI as a gold-standard for diagnosis. Inter-observer agreements were calculated with k-statistics. A p-value of <0.05 was considered as statistically significant. RESULTS: MRI depicted BME in 29/40 patients (72.50%) and in 43/240 partitions (17.91%). The consensus reading by R1 and R2 of DECT images allowed us to achieve 89.7% sensitivity (26/29 patients) and 81.8% specificity (9/11 patients). Regarding the partitions-basis analysis, BME was depicted by DECT in 39/43 partitions (90.69% sensitivity), and ruled out in 189/197 partitions (95.93% specificity). Sensitivity and specificity for the most involved partitions (talar dome) were both 95%. The inter-observer agreement for patients' analysis was substantial (k = 0.697), whereas for the partitions' analysis, it ranged from substantial (k = 0.724) to near perfect (k = 0.950). CONCLUSIONS: DECT can accurately diagnose BME of the ankle in a cohort of non-traumatic patients.

Role of diffusion tensor imaging of sciatic nerve in symptomatic patients with inconclusive lumbar MRI.

OBJECTIVE: To assess fractional anisotropy (FA) of sciatic nerve roots within the pelvis by using diffusion tensor imaging (DTI) in patients suffering from sciatica with inconclusive lumbar MRI. METHODS: This IRB-approved prospective study included 32 consecutive subjects (11 males and 21 females; mean age 32.2 years) between September 2019 and February 2020. All patients underwent DTI (TR/TE 5800/97 ms; b = 1000; slice thickness 3,5 mm; directions = 20) on a 1.5 T scanner (Siemens Aera). Seventeen patients were symptomatic, whereas 15 patients served as control group. DTI data were analyzed by two radiologists (25 and 11 years of experience, respectively) blinded to clinical data. Each radiologist placed two ROIs on the nerve roots at three different levels. Diagnostic accuracy values of FA numbers were calculated by using receiver operator curves (ROC) and relative area under the curve (AUC), by using clinical findings as standard of reference. Inter-observer agreement was calculated with k-statistics. Paired T-test and Mann-Whitney test were used for comparison accordingly to data distribution. A value of p < 0.05 was considered statistically significant. RESULTS: Among the 17 symptomatic patients, FA values were significantly lower in the affected side at all levels (p < 0.05). The FA ratio (FA affected side/FA unaffected side) of symptomatic patients was significantly lower compared to control group at level 1 (p = 0.0005) and level 2 (p = 0.0006). Using a threshold of 0.90 for level 1 and 0.73 for level 2, 76 % and 71 % sensitivity and 100 % and 87 % specificity were achieved, respectively. CONCLUSION: DTI can quantitatively demonstrate sciatic nerve roots impairment within the pelvis.