Research Article: Effect of reduced z-axis scan coverage on diagnostic performance and radiation dose of neck computed tomography in patients with suspected cervical abscess

Date Published: July 5, 2017

Publisher: Public Library of Science

Author(s): Jakob Weiss, Michael Maurer, Dominik Ketelsen, Mike Notohamiprodjo, Dominik Zinsser, Julian L. Wichmann, Konstantin Nikolaou, Fabian Bamberg, Ahmed E. Othman, Carlos Zaragoza.

http://doi.org/10.1371/journal.pone.0180671

Abstract

To evaluate the effect of reduced z-axis scan coverage on diagnostic performance and radiation dose of neck CT in patients with suspected cervical abscess.

Fifty-one patients with suspected cervical abscess were included and underwent contrast-enhanced neck CT on a 2nd or 3rd generation dual-source CT system. Image acquisition ranged from the aortic arch to the upper roof of the frontal sinuses (CTstd). Subsequently, series with reduced z-axis coverage (CTred) were reconstructed starting at the aortic arch up to the orbital floor. CTstd and CTred were independently assessed by two radiologists for the presence/absence of cervical abscesses and for incidental and alternative findings. In addition, diagnostic accuracy for the depiction of the cervical abscesses was calculated for both readers. Furthermore, DLP (dose-length-product), effective dose (ED) and organ doses were calculated and compared for CTred and CTstd, using a commercially available dose management platform.

A total of 41 abscesses and 3 incidental/alternative findings were identified in CTstd. All abscesses and incidental/alternative findings could also be detected on CTred resulting in a sensitivity and specificity of 1.0 for both readers. DLP, ED and organ doses of the brain, the eye lenses, the red bone marrow and the salivary glands of CTred were significantly lower than for CTstd (p<0.001). Reducing z-axis coverage of neck CT allows for a significant reduction of effective dose and organ doses at similar diagnostic performance as compared to CTstd.

Partial Text

Cervical abscesses can arise as a complication from various infectious and neoplastic diseases of the naso-pharyngeal area [1,2]. Contrast-enhanced CT imaging of the neck has become a well-established diagnostic tool to assess the primary focus and potential complications, such as venous thrombosis or mediastinitis [3,4]. For a reliable coverage of all possible abscess localizations and related complications, a scan range from the skull base to the aortic arch is recommended [5].

This retrospective study of routine clinical data was approved by the local ethic committee of the University of Tuebingen, which waived the requirement for written informed consent.

Contrast-enhanced neck CT was successfully performed in all patients (age 50.2±16.1 [range 22–92]; male 28; female 23) and all examinations were included in the final analysis. The mean scan range could be reduced significantly by approximately 24% for CTred as compared to CTstd (21.4±3.0 cm vs. 27.9±3.3 cm, respectively; p<0.001). An image example is provided in Fig 4. Further patient demographics are provided in Table 1. In this study, we evaluated the effect of a reduced z-axis scan coverage on diagnostic performance and radiation dose in patients with suspected cervical abscesses. Our results indicate that a reduced scan range allows for a significant reduction of effective dose and organ doses at similar diagnostic performance as compared to the standard coverage examination. In conclusion, our findings indicate that reducing z-axis coverage of neck CT allows for a significant reduction of effective dose and organ doses in patients with clinically suspected cervical abscess at similar diagnostic performance as compared to CTstd.   Source: http://doi.org/10.1371/journal.pone.0180671

 

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