Can We Perform CT of the Appendix with Less Than 1 mSv? A De-escalating Dose-simulation Study
- 116 Downloads
To systematically explore the lowest reasonably achievable radiation dose for appendiceal CT using an iterative reconstruction (IR) in young adults.
We prospectively included 30 patients who underwent 2.0-mSv CT for suspected appendicitis. From the helical projection data, 1.5-, 1.0- and 0.5-mSv CTs were generated using a low-dose simulation tool and the knowledge-based IR. We performed step-wise non-inferiority tests sequentially comparing 2.0-mSv CT with each of 1.5-, 1.0- and 0.5-mSv CT, with a predetermined non-inferiority margin of 0.06. The primary end point was the pooled area under the receiver-operating-characteristic curve (AUC) for three abdominal and three non-abdominal radiologists.
For the abdominal radiologists, the non-inferiorities of 1.5-, 1.0- and 0.5-mSv CT to 2.0-mSv CT were sequentially accepted [pooled AUC difference: 2.0 vs. 0.5 mSv, 0.017 (95% CI: -0.016, 0.050)]. For the non-abdominal radiologists, the non-inferiorities of 1.5- and 1.0-mSv CT were accepted; however, the non-inferiority of 0.5-mSv CT could not be proved [pooled AUC difference: 2.0 vs. 1.0 mSv, -0.017 (-0.070, 0.035) and 2.0 vs. 0.5 mSv, 0.045 (-0.071, 0.161)].
The 1.0-mSv appendiceal CT was non-inferior to 2.0-mSv CT in terms of diagnostic performance for both abdominal and non-abdominal radiologists; 0.5-mSv appendiceal CT was non-inferior only for abdominal radiologists.
• For both abdominal and non-abdominal radiologists, 1.0-mSv appendiceal CT could be feasible.
• The 0.5-mSv CT was non-inferior to 2.0-mSv CT only for expert abdominal radiologists.
• Reader experience is an important factor affecting diagnostic impairment by low-dose CT.
KeywordsAppendicitis Prospective studies Tomography, X-ray computed ROC curve Sensitivity and specificity
Area under the receiver-operating-characteristic curve
We thank Kyung Hwa Han in Yonsei University College of Medicine for her advice on sample size calculation.
Compliance with ethical standards
The scientific guarantor of this publication is Kyoung Ho Lee.
Conflict of interest
One of the co-authors (Amar C. Dhanantwari) is an employee of Philips. He contributed to imaging processing regarding radiation dose simulation and manuscript editing, but did not interfere with the medical interpretation proposed in this study. Otherwise, there are no conflicts of interest to declare.
Statistics and biometry
One of the authors has significant statistical expertise.
Written informed consent was obtained from all subjects (patients) in this study.
Institutional Review Board approval was obtained.
• diagnostic study
• performed at one institution
- 9.Mei K, Kopp FK, Bippus R et al (2017) Is multidetector CT-based bone mineral density and quantitative bone microstructure assessment at the spine still feasible using ultra-low tube current and sparse sampling? Eur Radiol. https://doi.org/10.1007/s00330-017-4904-y
- 14.Ahn S (2014) LOCAT (Low-dOse Computed tomography for Appendicitis Trial) comparing clinical outcomes following low- vs standard-dose computed tomography as the first-line imaging test in adolescents and young adults with suspected acute appendicitis: study protocol for a randomized controlled trial. Trials 15:28CrossRefPubMedPubMedCentralGoogle Scholar
- 20.Rosai J, Ackerman LV (2011) Appendix. In: Rosai J (ed) Rosai and Ackerman's surgical pathology. Mosby, St. Louis, pp 714–718Google Scholar
- 32.United Nations Scientific Committee on the Effects of Atomic Radiation. Sources and effects of ionizing radiation. Medical radiation exposures, annex A (2008) Report to the General Assembly with annexes. United Nations, New YorkGoogle Scholar
- 35.Solomon J, Marin D, Roy Choudhury K, Patel B, Samei E (2017) Effect of radiation dose reduction and reconstruction algorithm on image noise, contrast, resolution, and detectability of subtle hypoattenuating liver lesions at multidetector CT: filtered back projection versus a commercial model-based iterative reconstruction algorithm. Radiology 284:777–787CrossRefPubMedPubMedCentralGoogle Scholar