Ryan Kohlbrenner

Quantitative Radiology: Automated CT Liver Volumetry Compared With Interactive Volumetry and Manual Volumetry

OBJECTIVE The purpose of this study was to evaluate automated CT volumetry in the assessment of living-donor livers for transplant and to compare this technique with software-aided interactive volumetry and manual volumetry. MATERIALS AND METHODS Hepatic CT scans of 18 consecutively registered prospective liver donors were obtained under a liver transplant protocol. Automated liver volumetry was developed on the basis of 3D active-contour segmentation. To establish reference standard liver volumes, a radiologist manually traced the contour of the liver on each CT slice. We compared the results obtained with automated and interactive volumetry with those obtained with the reference standard for this study, manual volumetry. RESULTS The average interactive liver volume was 1553 ± 343 cm(3), and the average automated liver volume was 1520 ± 378 cm(3). The average manual volume was 1486 ± 343 cm(3). Both interactive and automated volumetric results had excellent agreement with manual volumetric results (intraclass correlation coefficients, 0.96 and 0.94). The average user time for automated volumetry was 0.57 ± 0.06 min/case, whereas those for interactive and manual volumetry were 27.3 ± 4.6 and 39.4 ± 5.5 min/case, the difference being statistically significant (p < 0.05). CONCLUSION Both interactive and automated volumetry are accurate for measuring liver volume with CT, but automated volumetry is substantially more efficient.

Patient Radiation Dose Reduction during Transarterial Chemoembolization Using a Novel X-Ray Imaging Platform

PURPOSE To evaluate radiation dose reduction in patients undergoing transarterial chemoembolization with the use of a new image acquisition and processing platform. MATERIALS AND METHODS Radiation-dose data were obtained from 176 consecutive chemoembolization procedures in 135 patients performed in a single angiography suite. From January 2013 through October 2013, 85 procedures were performed by using our institutions standard fluoroscopic settings. After upgrading the x-ray fluoroscopy system with an image acquisition and processing platform designed to reduce image noise and reduce skin entrance dose, 91 chemoembolization procedures were performed from November 2013 through December 2014. Cumulative dose-area product (CDAP), cumulative air kerma (CAK), and total fluoroscopy time were recorded for each procedure. Image quality was assessed by three interventional radiologists blinded to the x-ray acquisition platform used. RESULTS Patient radiation dose indicators were significantly lower for chemoembolization procedures performed with the novel imaging platform. Mean CDAP decreased from 3,033.2 dGy·cm(2) (range, 600.3-9,404.1 dGy·cm(2)) to 1,640.1 dGy·cm(2) (range, 278.6-6,779.9 dGy·cm(2); 45.9% reduction; P < .00001). Mean CAK decreased from 1,445.4 mGy (range, 303.6-5,233.7 mGy) to 971.7 mGy (range, 144.2-3,512.0 mGy; 32.8% reduction; P < .0001). A 20.3% increase in mean total fluoroscopy time was noted after upgrading the imaging platform, but blinded analysis of the image quality revealed no significant degradation. CONCLUSIONS Although a small increase in fluoroscopy time was observed, a significant reduction in patient radiation dose was achieved by using the optimized imaging platform, without image quality degradation.

Catheter directed interventions for acute deep vein thrombosis

Venous thromboembolism (VTE) is an extremely common form of vascular disease and impacts a great number of patients worldwide. Acute deep vein thrombosis (DVT) is a subset of VTE and is traditionally been treated with anticoagulation. There is good quality data which suggests the use of catheter directed interventions for the treatment of acute DVT with the aim of reducing post-thrombotic syndrome (PTS). The present review will discuss the various therapies available for acute DVT, focusing on catheter directed interventions, ranging from traditional anticoagulation to the most novel forms of aspiration thrombectomy.

SU‐C‐18C‐06: Radiation Dose Reduction in Body Interventional Radiology: Clinical Results Utilizing a New Imaging Acquisition and Processing Platform

PURPOSE To quantify the patient radiation dose reduction achieved during transarterial chemoembolization (TACE) procedures performed in a body interventional radiology suite equipped with the Philips Allura Clarity imaging acquisition and processing platform, compared to TACE procedures performed in the same suite equipped with the Philips Allura Xper platform. METHODS Total fluoroscopy time, cumulative dose area product, and cumulative air kerma were recorded for the first 25 TACE procedures performed to treat hepatocellular carcinoma (HCC) in a Philips body interventional radiology suite equipped with Philips Allura Clarity. The same data were collected for the prior 85 TACE procedures performed to treat HCC in the same suite equipped with Philips Allura Xper. Mean values from these cohorts were compared using two-tailed t tests. RESULTS Following installation of the Philips Allura Clarity platform, a 42.8% reduction in mean cumulative dose area product (3033.2 versus 1733.6 mGycm∧2, p < 0.0001) and a 31.2% reduction in mean cumulative air kerma (1445.4 versus 994.2 mGy, p < 0.001) was achieved compared to similar procedures performed in the same suite equipped with the Philips Allura Xper platform. Mean total fluoroscopy time was not significantly different between the two cohorts (1679.3 versus 1791.3 seconds, p = 0.41). CONCLUSION This study demonstrates a significant patient radiation dose reduction during TACE procedures performed to treat HCC after a body interventional radiology suite was converted to the Philips Allura Clarity platform from the Philips Allura Xper platform. Future work will focus on evaluation of patient dose reduction in a larger cohort of patients across a broader range of procedures and in specific populations, including obese patients and pediatric patients, and comparison of image quality between the two platforms. Funding for this study was provided by Philips Healthcare, with 5% salary support provided to authors K. Pallav Kolli and Robert G. Gould for time devoted to the study. Data acquisition and analysis was performed by the authors independent of the funding source.

TH‐C‐304A‐10: Computer‐Aided Measurement of Liver Volumes in CT by Means of Fast‐Marching and Level‐Set Segmentation

Purpose: Measuring the liver volume by manual tracing of the liver boundary on arterial‐phase CTimages is time‐consuming. Our purpose was to develop an automated liver extraction scheme based on a 3D level‐set segmentation technique for measuring liver volumes. Material and Methods: Hepatic CT scans of eighteen prospective liver donors were obtained under a liver transplant protocol. We developed an automated liver segmentation scheme for volumetry of the liver in CT. Our scheme consisted of five steps. First, a 3D anisotropic smoothing filter was applied to CTimages for removing noise while preserving the structures in the liver, followed by an edge enhancement filter and a nonlinear gray‐scale enhancement filter for enhancing the liver boundary. By using the boundary‐enhanced image as a speed function, a 3D fast‐marching algorithm generated an initial surface that roughly estimated the shape of the liver. A 3D level‐set segmentation algorithm refined the initial surface so as to fit the liver boundary more accurately. Automated volumes were compared to manually determined liver volumes. Results: The mean liver volume obtained with our scheme was 1598 cc (range: 1002–2415 cc), whereas the mean manual volume was 1535 cc (range: 1007–2435 cc). The mean absolute difference between automated and manual volumes was 128 cc (9.5%). The two volumetrics reached an excellent agreement (the intra‐class correlation coefficient was 0.89) with no statistically significant difference (P=0.13). The processing time by the automated method was 2–5 min. per case (Intel, Xeon, 2.7 GHz), whereas that by manual segmentation was approximately 50–60 min. per case. Conclusion:CTliver volumetrics based on an automated scheme agreed excellently with manual volumetrics, and required substantially less completion time. Our automated scheme provides an efficient and accurate way of measuring liver volumes in CT; thus, it would be useful for radiologists in their measurement of liver volumes.