The application study of dual-energy CT nonlinearblending technique in pulmonary angiography

Objective This study aimed to explore the feasibility of enhancing image quality in computed tomography(CT) pulmonary angiography (CTPA) and reducing radiation dose using the nonlinear blending (NLB)technique of dual-energy CT.Methods A total of 61 patients scheduled for CTPA were enrolled, and 30 patients underwent dual-energyscanning. Nonlinear blending images (NLB group) and three groups of linear blending images (LB group,80 kV group, and 140 kV group) were reconstructed after scanning;31 patients underwent single-energyscanning (120 kV group). The CT values and standard deviations of the pulmonary trunk, left and rightpulmonary arteries, and ipsilateral back muscle at the bifurcation level of the left and right pulmonaryarteries were measured. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the fivegroups were calculated. The subjective image quality of the five groups was assessed. The radiation dosesof the dual- and single-energy groups were recorded and calculated.Results The CNR and SNR values of blood vessels in the NLB group were significantly higher than thosein the LB, 140 kV, and 80 kV groups (CNR of pulmonary artery trunk: t = 3.50, 4.06, 7.17, all P < 0.05;SNRof pulmonary trunk: t = 3.76, 4.71, 6.92, all P < 0.05). There were no statistical differences in the CNR andSNR values between the NLB group and 120 kV group (P > 0.05). The effective radiation dose of the dualenergygroup was lower than that of the single-energy group (t = –4.52, P < 0.05). The subjective scores ofimages in the NLB group were the highest (4.28 ± 0.74).Conclusion The NLB technique of dual-energy CT can improve the image quality of CTPA and reducethe radiation dose, providing more reliable imaging data for the clinical diagnosis of pulmonary embolism.

Could the number of CT angiograms be reduced in emergency department patients suspected of pulmonary embolism?

BACKGROUND:This study was undertaken to identify the prevalence of pulmonary embolism(PE) in the emergency department(ED) of an urban teaching hospital and also to test a Bayesian model in estimating the number of CT pulmonary angiography(CTA) expected to be performed in an emergency department.METHODS:The data for this study was obtained through a retrospective review of electronic medical records for all ED patients suspected of PE who underwent chest CTA or ventilation perfusion scanning(V/Q) between 2009 and 2010.The data is presented as means and standard deviation for continuous variables and percentages with 95%confidence intervals(95%CI) for proportions.The prevalence of PE was used as pre-test probability in the Bayesian model.Post-test probability was obtained using a Fagan nomogram and likelihood ratios for CTA.RESULTS:A total of 778 patients(560 females) with mean age of 50 years(range 18-98 years)were enrolled(98.3%underwent chest CTA and 1.7%underwent V/Q scan).A total of 69 patients had PE,rendering an overall prevalence of 8.9%(95%CI,7.1%to 11.1%) for PE.We calculated that132 CTA's per year could be avoided in our institution,without compromising safe exclusions of PE(keeping post-test probability of PE below 2%).CONCLUSIONS:Despite differences in our patient populations and /or study designs,the prevalence of PE in our institution is about average compared to other institutions.Our proposed model for calculating redundant chest CTA is simple and can be used by institutions to identify overuse of CTA.

Value of CT pulmonary arteriography and venography in the evaluation of venous thromboembolism in a multiracial Asian population

Background There is increasing evidence that CT pulmonary arteriography and venography allow a better diagnostic yield for deep vein thrombosis （DVT） in suspected acute pulmonary embolism （PE）. The aim was to investigate the value for using such an approach in a multiracial Asian population. Methods A total of 135 consecutive subjects with clinically suspected PE in various clinical settings （postoperative in 23 subjects） were referred and evaluated for venous thromboemboUsm using CT pulmonary arteriography and venography in a tertiary hospital, Malaysia. The distribution of DVT was assessed based on the frequency rate of thrombosis in a particular anatomical region （inferior vena cava, pelvic, femoral and popliteal）. Results In 130 subjects, excluding 5 subjects having poor images, both DVT and PE were detected in 11.5% （15/130） subjects and DVT alone was detected in 6.9% （9/130） subjects giving a combined rate of venous thromboembolism of 18.4%. A history of malignancy was significantly associated with positive scans, P=0.02. It was found that left pelvic veins （18.2%） and left femoral veins （19.5%） were more commonly thrombosed in this population. Conclusion CT pulmonary arteriography and venography is a useful technique in the evaluation of venous thromboembolism in a multi-racial Asian population.

Clinical study on high-resolution CT and pulmonary function in severe acute respiratory syndrome patients during recovery phase

Severe acute respiratory syndrome (SARS) is an acute respiratory infectious disease caused by a novel coronavirus, firstly broke out in November 2002 in Guangdong and prevailed quickly in Beijing, Hong Kong, Taiwan and other regions of China. It was one of the most potential pandemic diseases and had affected more than 20 other countries.^(1,2) There have been a lot of resear-ches^(2-7) in terms of its etiology, epidemiology, pathogenesis, clinical characteristics, diagnostics, treatment and prevention, vaccines and so on.Along with control of the epidemic situation, a great number of SARS patients were in the recovery phase, therefore, we undertook a half-year follow-up investigation on their clinical, laboratory and image situations.