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Original Research

Appropriate Patient Selection at Abdominal Dual-Energy CT Using 80 kV: Relationship between Patient Size, Image Noise, and Image Quality

Published Online:Dec 1 2010https://doi.org/10.1148/radiol.10092016

Abstract

Abdominal CT at 80 kV can be performed with acceptable image quality when careful attention is paid to CT acquisition techniques, patient size, and organ of interest.

Purpose

To determine the computed tomographic (CT) detector configuration, patient size, and image noise limitations that will result in acceptable image quality of 80-kV images obtained at abdominal dual-energy CT.

Materials and Methods

The Institutional Review Board approved this HIPAA-compliant retrospective study from archival material from patients consenting to the use of medical records for research purposes. A retrospective review of contrast material–enhanced abdominal dual-energy CT scans in 116 consecutive patients was performed. Three gastrointestinal radiologists noted detector configuration and graded image quality and artifacts at specified levels—midliver, midpancreas, midkidneys, and terminal ileum—by using two five-point scales. In addition, an organ-specific enhancement-to-noise ratio and background noise were measured in each patient. Patient size was measured by using the longest linear dimension at the level of interest, weight, lean body weight, body mass index, and body surface area. Detector configuration, patient sizes, and image noise levels that resulted in unacceptable image quality and artifact rankings (score of 4 or higher) were determined by using multivariate logistic regression.

Results

A 14 × 1.2-mm detector configuration resulted in fewer images with unacceptable quality than did the 64 × 0.6-mm configuration at all anatomic levels (P = .004, .01, and .02 for liver, pancreas, and kidneys, respectively). Image acceptability for the kidneys and ileum was significantly greater than that for the liver for all readers and detector configurations (P < .001). For the 14 × 1.2-mm detector configuration, patient longest linear dimensions yielding acceptable image quality across readers ranged from 34.9 to 35.8 cm at the four anatomic levels.

Conclusion

An 80-kV abdominal CT can be performed with appropriate diagnostic quality in a substantial percentage of the population, but it is not recommended beyond the described patient size for each anatomic level. The 14 × 1.2-mm detector configuration should be preferred.

© RSNA, 2010

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Article History

Received October 29, 2009; revision requested December 18; revision received April 19, 2010; accepted May 20; final version accepted July 7.
Published online: Dec 2010
Published in print: Dec 2010