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George, Elizabeth

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George

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Elizabeth

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George, Elizabeth
Author's Publications: search.filters.isAuthorOfPublication.f0f4a8f2-1a7c-4aa4-8e1f-739681447ac8

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    Contrast inhomogeneity in CT angiography of the abdominal aortic aneurysm
    (Elsevier BV, 2016) George, Elizabeth; Giannopoulos, Andreas A.; Aghayev, Ayaz; Rohatgi, Saurabh; Imanzadeh, Amir; Antoniadis, Antonios P.; Kumamaru, Kanako; Chatzizisis, Yiannis; Dunne, Ruth Mary; Steigner, Michael; Hanley, Michael; Gravereaux, Edwin; Rybicki, Frank John; Mitsouras, Dimitrios
    Background If undetected, infrarenal Abdominal Aortic Aneurysm (AAA) growth can lead to rupture, a high-mortality complication. Some AAA patients exhibit inhomogeneous luminal contrast attenuation at first-pass CT angiography (CTA). This study assesses the association between this observation and aneurysm growth. Methods Sixty-seven consecutive pre-repair AAA CTAs were included in this retrospective study. The “Gravitational Gradient” (GG), defined as the ratio of the mean attenuation in a region-of-interest placed posteriorly to that in a region-of-interest placed anteriorly within the lumen of the aortic aneurysm on a single axial slice, and the maximum aneurysm diameter were measured from each CT data set. “AAA Contrast Inhomogeneity” was defined as the absolute value of the difference between the GG and 1.0. Univariate and multivariate logistic regression was used to assess the association of aneurysm growth >0.4 and >1.0 cm/year to AAA Contrast Inhomogeneity, aneurysm diameter, patient characteristics and cardiovascular co-morbidities. Results AAA Contrast Inhomogeneity was not correlated to aneurysm diameter (p=0.325). In multivariable analysis that included initial aneurysm diameter and AAA Contrast Inhomogeneity, both factors were significantly associated with rapid aneurysm growth (initial diameter: p=0.0029 and 0.011, and, AAA Contrast Inhomogeneity: p=0.045 and 0.048 for growth >0.4 cm/year and >1 cm/year respectively). Conclusions AAA Contrast Inhomogeneity is a common observation in first-pass CTA. It is associated with rapid aneurysm growth, independent of and incremental to aneurysm diameter.
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    Accuracy and reproducibility of automated, standardized coronary transluminal attenuation gradient measurements
    (Springer Nature, 2014) Chatzizisis, Yiannis; George, Elizabeth; Cai, Tianrun; Fulwadhva, Urvi P; Kumamaru, Kanako; Schultz, Kurt; Fujisawa, Yasuko; Rassi, Carlos; Steigner, Michael; Mather, Richard T.; Blankstein, Ron; Rybicki, Frank John; Mitsouras, Dimitrios
    Purpose Coronary Computed Tomography Angiography (CCTA) contrast opacification gradients, or Transluminal Attenuation Gradients (TAG) offer incremental value to predict functionally significant lesions. This study introduces and evaluates an automated gradients software package that can potentially supplant current, labor-intensive manual TAG calculation methods. Methods All 60 major coronary arteries in 20 patients who underwent a clinically indicated single heart beat 320×0.5 mm detector row CCTA were retrospectively evaluated by two readers using a previously validated manual measurement approach and two additional readers who used the new automated gradient software. Accuracy of the automated method against the manual measurements, considered the reference standard, was assessed via linear regression and Bland-Altman analyses. Inter- and intra-observer reproducibility and factors that can affect accuracy or reproducibility of both manual and automated TAG measurements, including CAD severity and iterative reconstruction, were also assessed. Results Analysis time was reduced by 68% when compared to manual TAG measurement. There was excellent correlation between automated TAG and the reference standard manual TAG. Bland-Altman analyses indicated low mean differences (1 HU/cm) and narrower inter- and intra-observer limits of agreement for automated compared to manual measurements (25% and 36% reduction with automated software, respectively). Among patient and technical factors assessed, none affected agreement of manual and automated TAG measurement. Conclusion Automated 320×0.5 mm detector row gradient software reduces computation time by 68% with high accuracy and reproducibility.
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    Reduced Radiation Exposure for Face Transplant Surgical Planning Computed Tomography Angiography
    (Public Library of Science, 2013) Schultz, Kurt; George, Elizabeth; Mullen, Katherine; Steigner, Michael; Mitsouras, Dimitrios; Bueno, Ericka M.; Pomahac, Bohdan; Rybicki, Frank John; Kumamaru, Kanako
    Objective: To test the hypothesis that wide area detector face transplant surgical planning CT angiograms with simulated lower radiation dose and iterative reconstruction (AIDR3D) are comparable in image quality to those with standard tube current and filtered back projection (FBP) reconstruction. Materials and Methods The sinograms from 320-detector row CT angiography of four clinical candidates for face transplantation were processed utilizing standard FBP, FBP with simulated 75, 62, and 50% tube current, and AIDR3D with corresponding dose reduction. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured at muscle, fat, artery, and vein. Image quality for each reconstruction strategy was assessed by two independent readers using a 4-point scale. Results: Compared to FBP, the median SNR and CNR for AIDR3D images were higher at all sites for all 4 different tube currents. The AIDR3D with simulated 50% tube current achieved comparable SNR and CNR to FBP with standard dose (median muscle SNR: 5.77 vs. 6.23; fat SNR: 6.40 vs. 5.75; artery SNR: 43.8 vs. 45.0; vein SNR: 54.9 vs. 55.7; artery CNR: 38.1 vs. 38.6; vein CNR: 49.0 vs. 48.7; all p-values >0.19). The interobserver agreement in the image quality score was good (weighted κ = 0.7). The overall score and the scores for smaller arteries were significantly lower when FBP with 50% dose reduction was used. The AIDR3D reconstruction images with 4 different simulated doses achieved a mean score ranging from 3.68 to 3.82 that were comparable to the scores from images reconstructed using FBP with original dose (3.68–3.77). Conclusions: Simulated radiation dose reduction applied to clinical CT angiography for face transplant planning suggests that AIDR3D allows for a 50% reduction in radiation dose, as compared to FBP, while preserving image quality.