Computed Tomography Attenuation Values of the High-Attenuating Crescent Sign Can Discriminate Between Rupture,
Tatsuo Ueda1, Hiromitsu Hayashi1, Takahiro Ando1
1Department of Radiology, Nippon Medical School Hospital.
Insights
The high-attenuating crescent (HAC) sign
Area of Science:
- Radiology
- Vascular Surgery
- Medical Imaging
Background:
- The high-attenuating crescent (HAC) sign on computed tomography (CT) can indicate impending aortic aneurysm (AA) rupture.
- The precise relationship between HAC sign CT attenuation values and the severity of AA remains unclear.
Purpose of the Study:
- To compare CT attenuation values of the HAC sign in patients with ruptured, impending ruptured, and non-ruptured AA.
- To determine if HAC sign CT values can predict AA rupture risk.
Main Methods:
- Retrospective analysis of 76 patients with HAC sign-associated AA.
- Measurement of HAC sign (H) and aortic lumen (A) CT attenuation values and calculation of the H/A ratio.
- Comparison of H and H/A ratios across rupture, impending rupture, and non-rupture groups.
Main Results:
- Both H and H/A ratios were significantly higher in rupture and impending rupture groups compared to the non-rupture group (P<0.001).
- The H/A ratio was significantly higher in the rupture group than in the impending rupture group (P=0.038).
- Optimal cut-offs for predicting impending rupture were identified as 50.3 Hounsfield units for H (AUC=0.875) and 1.3 for H/A ratio (AUC=0.909).
Conclusions:
- Elevated HAC sign CT attenuation values and H/A ratios are associated with increased risk of AA rupture.
- These CT-derived metrics can aid in differentiating between ruptured, impending ruptured, and non-ruptured AA.
Background:
Although the high-attenuating crescent (HAC) sign can indicate aortic aneurysm (AA) impending rupture, the relation of its computed tomography (CT) value to the aneurysmal status remains unclear. This study compared the HAC sign CT-attenuation values among rupture, impending rupture, and non-rupture AA cases.
Methods And Results:
This included 76 patients (mean age: 77.0 years) diagnosed with HAC sign-associated AA between January 2005 and July 2015. The CT-attenuation values of the HAC sign (H) and aortic lumen (A) using region-of-interest methodology were measured and the H/A ratio was calculated. The study classified patients into the rupture group (R-G, n=36), impending rupture group (IR-G, n=16), and non-rupture group (NR-G, n=24); the H and the H/A ratio were compared among them. Additionally, the H and the H/A ratio cut-offs between the IR-G and NR-G groups were evaluated. The H and the H/A ratio were significantly higher in the R-G and IR-G than in the NR-G (both P<0.001); the H/A ratio was significantly higher in the R-G than in the IR-G (P=0.038). The optimal cut-off for H between the IR-G and NR-G was 50.3 Hounsfield units (area under the curve [AUC]=0.875; sensitivity=87.5%; specificity=87.5%), and that for the H/A ratio was 1.3 (AUC=0.909; sensitivity=91.7%; specificity=87.5%).
Conclusions:
Among patients with AA, the H and the H/A ratio were significantly higher in cases of rupture and impending rupture than in those of non-rupture.
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