CT liver perfusion in patients with hepatocellular carcinoma: can we modify acquisition protocol to reduce patient exposure?

OBJECTIVES: To investigate the potential of decreasing the number of scans and associated radiation exposure involved in CT liver perfusion (CTLP) dynamic studies for hepatocellular carcinoma (HCC) assessment. METHODS: Twenty-four CTLP image datasets of patients with HCC were retrospectively analyzed. All examinations were performed on a modern CT system using a standard acquisition protocol involving 35 scans with 1.7 s interval. A deconvolution-based or a standard algorithm was employed to compute ten perfusion parametric maps. 3D ROIs were positioned on 33 confirmed HCCs and non-malignant parenchyma. Analysis was repeated for two subsampled datasets generated from the original dataset by including only the (a) 18 odd-numbered scans with 3.4 s interval and (b) 18 first scans with 1.7 s interval. Standard and modified datasets were compared regarding the (a) accuracy of calculated perfusion parameters, (b) power of parametric maps to discriminate HCCs from liver parenchyma, and (c) associated radiation exposure. RESULTS: When the time interval between successive scans was doubled, perfusion parameters of HCCs were found unaffected (p > 0.05) and the discriminating efficiency of parametric maps was preserved (p < 0.05). In contrast, significant differences were found for all perfusion parameters of HCCs when acquisition duration was reduced to half (p < 0.05), while the discriminating efficiency of four parametric maps was significantly deteriorated (p < 0.05). Modified CTLP acquisition protocols were found to involve 48.5% less patient exposure. CONCLUSIONS: Doubling the interscan time interval may considerably reduce radiation exposure from CTLP studies performed for HCC evaluation without affecting the diagnostic efficiency of perfusion maps generated with either standard or deconvolution-based mathematical model. KEY POINTS: • CT liver perfusion for HCC diagnosis/assessment is not routinely used in clinical practice mainly due to the associated high radiation exposure. • Two alternative acquisition protocols involving 18 scans of the liver were compared with the standard 35-scan protocol. • Increasing the time interval between successive scans to 3.4 s was found to preserve the accuracy of computed perfusion parameters derived with a standard or a deconvolution-based model and to reduce radiation exposure by 48.5%.

Editor's Choice - Systematic Review and Meta-Analysis of the Impact of Institutional and Surgeon Procedure Volume on Outcomes After Ruptured Abdominal Aortic Aneurysm Repair.

OBJECTIVE: To investigate whether there is a correlation between institutional or surgeon case volume and outcomes in patients with ruptured abdominal aortic aneurysm (rAAA). DATA SOURCES: The Healthcare Database Advanced Search interface developed by the National Institute of Health and Care Excellence was used to search MEDLINE, Embase, CINAHL, and CENTRAL. REVIEW METHODS: The systematic review complied with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines with the protocol registered in PROSPERO (CRD42020213121). Prognostic studies were considered comparing outcomes of patients with rAAA undergoing repair in high and low volume institutions or by high and low volume surgeons. Pooled estimates for peri-operative mortality were calculated using the odds ratio (OR) and 95% confidence intervals (CI), applying the Mantel-Haenszel method. Analysis of adjusted outcome estimates was performed with the generic inverse variance method. RESULTS: Thirteen studies reporting a total of 120 116 patients were included. Patients treated in low volume centres had a statistically significantly higher peri-operative mortality than those treated in high volume centres (OR 1.39; 95% CI 1.22 - 1.59). Subgroup analysis showed a mortality difference in favour of high volume centres for both endovascular aneurysm repair (EVAR; OR 1.61, 95% CI 1.11 - 2.35) and open repair (OR 1.50, 95% CI 1.25 - 1.81). Adjusted analysis showed a benefit of treatment in high volume centres for open repair (OR 1.68, 95% CI 1.21 - 2.33) but not for EVAR (OR 1.42, 95% CI 0.84 - 2.41). Differences in peri-operative mortality between low and high volume surgeons were not statistically significant for either EVAR (OR 1.06, 95% CI 0.59 - 1.89) or open surgical repair (OR 1.18, 95% CI 0.87 - 1.63). CONCLUSION: A high institutional volume may result in a reduction of peri-operative mortality following surgery for rAAA. This peri-operative survival advantage is more pronounced for open surgery than EVAR. Individual surgeon caseload was not found to have a significant impact on outcomes.

CT coronary angiography in asymptomatic male patients with high atherosclerosis risk: Is it justified?

PURPOSE: To study the necessity of coronary artery screening with computerized tomography coronary angiography (CTCA) in asymptomatic male patients. MATERIAL AND METHODS: A total of 226 asymptomatic male patients aged over 50 years were included in this prospective study, according to a clinical protocol approved by the Heraklion University Hospital's Ethics Committee. All participants had at least 3 or more known atherosclerosis risk factors. All patients had none or normal noninvasive cardiological tests in the past and had no contraindications for CTCA. All patients gave their informed consent after being notified regarding contrast medium and radiation dose risks. RESULTS: Significant stenoses were found in 52 asymptomatic males (23%). Out of them, 38 male patients underwent invasive coronography and 14 patients were lost in follow-up. In 18 patients, no lesions were found (47.4%). In the other 20 (52.6%) patients, 28 lesions were found. Stent placement was performed in 11 patients, bypass surgery was proposed in 3 patients, and in another 6 patients conservative treatment was suggested. Patients with findings in CTCA were more likely to have a family history of coronary artery disease, compared to patients with normal CTCA (P < 0.05 by using Fischer's Exact Test). Sensitivity of CTCA for significant stenosis was 74.3% with a specificity of 62%. CONCLUSION: CTCA may be used to screen for clinically significant coronary artery disease (CAD) in asymptomatic male patients, particularly those with positive family history or potentially high-risk patients with >3 risk factors for CAD.