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Journal of Thoracic Imaging:
doi: 10.1097/RTI.0000000000000059
Original Articles

Image Quality and Feasibility of an Ultralow-dose High-pitch Helical Triple–rule-out Computed Tomography Angiography Acquired in the Caudocranial Direction

Kligerman, Seth J. MD; White, Charles S. MD

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Purpose: The aim of this study was to assess the feasibility and image quality of a low-dose triple–rule-out (TRO) computed tomography (CT) angiogram on a second-generation dual-source CT scanner using a high-pitch helical acquisition.

Materials and Methods: Ten men (mean age 56.3 y, average body mass index 24.2) underwent TRO CT angiography using a high-pitch helical acquisition. Patients were imaged from the lung bases to the thoracic inlet in a caudocranial direction. A biphasic injection was administered at 6 mL/s. Study parameters including kVp, mAs, CT dose index volume, dose-length product, and effective dose were calculated. Image quality was independently assessed by 2 cardiothoracic radiologists using the following scale: 1—nondiagnostic; 2—moderately limited diagnostic ability; 3—mild limitation but diagnostic; 4—ideal. For each patient up to 23 structures were evaluated: 17 coronary segments, 3 pulmonary artery levels, 2 aortic sections, and the lung parenchyma. The unpaired t test and the Fisher exact test were used for comparison between patients scored at 80 and 100 kV.

Results: The average CT dose index volume, dose-length product, and effective dose for the TRO scans was 2.65, 81.9, and 1.39 mSv, respectively. Readers 1 and 2 scored 171/203 (83%) and 173/203 (84%) of the evaluated regions as ideal and 26/203 (12.8%) and 24/203 (11.8%) as being mildly limited, respectively. Each reader graded 6/203 (3.9%) as being moderately limited. No areas were nondiagnostic. Patients scanned at 80 kV had a significantly higher number of limited segments for readers 1 (P=0.0012) and 2 (P=0.0027).

Conclusions: Low-dose, high–image quality TRO scans can be effectively performed using a high-pitch helical acquisition.

© 2014 by Lippincott Williams & Wilkins


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