Dependent contrast layering sign on CT in patients irrespective of cardiac dysfunction and its clinical implications: A preliminary retrospective study

Purpose: CT findings of contrast layering in dependent areas of the central venous system and solid organs have been reported in the literature to be associated with imminent cardiac arrest. However, no systematic research has explored the association of this distinctive CT finding with cardiac arrest and mortality. Therefore, we investigated the radiological manifestations of dependent layering of contrast in various vascular structures and organs and its clinical implications.
Methods: A computerized search of radiological database was conducted using keywords “layering contrast” between January 2008 and January 2022. After reviewing CT scans of 226 patients that met the keyword criteria, 21 patients who exhibited the dependent contrast layering sign (DCLS) in vascular structures and organs were included in the final study population. Clinical data such as cardiac arrest within 2 hours, in-hospital mortality, and shock index ≥ 0.9 were collected. Number of involved structures in each patient is also investigated. Statistical significance and frequency regarding the association between radiologic findings and clinical data were analyzed.
Results: The distribution of DCLS across anatomical structures reveals IVC is involved in 90.5% of patients and followed by hepatic vein (80.9%), liver parenchyma and right atrium. Cardiac arrest within 2 hours is significantly more common in patients with DCLS in right atrium (p=0.02, odds ratio = 21.6) and liver parenchyma (p=0.01, odds ratio = 24.8). DCLS in liver parenchyma is associated with the highest rate of in-hospital mortality (4 of 7, 57.1%). The total number of involved structures (p=0.01) and the number of common structures (p=0.001) are significantly higher in patients with cardiac arrest within 2 hours.
Conclusions: The presence of DCLS in the right atrium and liver, as well as the larger number of involved structures, are significantly associated with impending cardiac arrest. Thus, it may offer additional insights for both radiologists and clinicians and aid in prompt initiation of resuscitative interventions before the onset of cardiac arrest. Nevertheless, larger prospective studies are warranted to validate the clinical relevance of DCLS across various vascular structures and organs.