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Acad Radiol. 2018 Aug;25(8):1075-1086. doi: 10.1016/j.acra.2017.12.012. Epub 2018 Feb 15.

Image Quality on Dual-energy CTPA Virtual Monoenergetic Images: Quantitative and Qualitative Assessment.

Author information

1
Department of Radiology, NYU Langone Health, 660 First Avenue, New York, NY 10016. Electronic address: bari.dane@nyumc.org.
2
Department of Radiology, NYU Langone Health, 660 First Avenue, New York, NY 10016.
3
Siemens Healthineers, Malvern, PA.
4
Fordham University, Bronx, New York.

Abstract

RATIONALE AND OBJECTIVES:

This study aims to determine the optimal photon energy for image quality of the pulmonary arteries (PAs) on dual-energy computed tomography (CT) pulmonary angiography (CTPA) utilizing low volumes of iodinated contrast.

MATERIALS AND METHODS:

The study received institutional review board exemption and was Health Insurance Portability and Accountability Act compliant. Adults (n = 56) who underwent dual-energy CTPA with 50-60 cc of iodinated contrast on a third-generation dual-source multidetector CT were retrospectively and consecutively identified. Twelve virtual monoenergetic kiloelectron volt (keV) image data sets (40-150 keV, 10-keV increments) were generated with a second-generation noise-reducing algorithm. Standard regions of interest were placed on main, right, left, and right interlobar pulmonary arteries; pectoralis muscle; and extrathoracic air. Attenuation [mean CT number (Hounsfield unit, HU)], noise [standard deviation (HU)], signal to noise (SNR), and contrast to noise ratio were evaluated. Three blinded chest radiologists rated (from 1 to 5, with 5 being the best) randomized monoenergetic and weighted-average images for attenuation and noise. P <.05 was considered significant.

RESULTS:

Region of interest mean CT number increased as keV decreased, with 40 keV having the highest value (P < .001). Mean SNR was highest for 40-60 keV (P <.05) (14.5-14.7) and was higher (P <.05) than all remaining energies (90-150 keV) for all vessel regions combined. Contrast to noise ratio was highest for 40 keV (P <.001) and decreased as keV increased. SNR was highest at 60 and 70 keV, only slightly higher than 40-50 keV (P <.05). Reader scores for 40-50 keV were greater than other energies and weighted-average images (P <.05).

CONCLUSIONS:

Kiloelectron volt images of 40-50 keV from the second-generation algorithm optimize attenuation on dual-energy CTPA and can potentially aid in interpretation and avoiding nondiagnostic examinations.

KEYWORDS:

CT pulmonary angiography; Monoenergetic; dual-energy CT; monochromatic; pulmonary embolism

PMID:
29398436
DOI:
10.1016/j.acra.2017.12.012
[Indexed for MEDLINE]

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