Reflux of CT contrast into the IVC: Defining boundaries between pathologic and iatrogenic reflux
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Date
2014-06-01
Authors
Fudge, Thomas
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Abstract
Background: Reflux of intravenous contrast into the inferior vena cava (IVC) or hepatic veins
seen on contrast enhanced computed tomography (CT) studies has been linked to right-sided
heart disease including tricuspid regurgitation (TR), pulmonary hypertension, and right
ventricular systolic dysfunction (RVSD). Current CT protocols call for increasingly faster contrast
injection rates, which have led to relatively frequent visualization of the reflux sign.
Objective: Assess the clinical role of reflux at high contrast injection rates while correcting for
right ventricular function obtained by pocket-sized echocardiography (PSE).
Methods: Patients having undergone contrast enhanced CT examination at rates of 3-6 ml/sec
were recruited to undergo a limited PSE examination. Presence and severity of IVC reflux on CT,
was compared to right ventricular fractional area change (< 35% = RVSD), TR, IVC diameter
and IVC collapse during sniff test.
Results: 86 patients underwent PSE. IVC reflux incidence was 79% (68/86), with 38 patients
exhibiting reflux to the suprahepatic level, and 30 having significant reflux (hepatic level). There
were no statistically significant differences between varying injection rates and RVSD. There
was a significant difference favoring greater reflux with RVSD when injection rates were
combined (P = 0.0393). In those with significant reflux, higher injection rates were linked to
higher Hounsfield units within the hepatic veins for both normal and RVD, but the population size
was too small to draw significance.
Conclusion: Although population numbers were too low for statistical significance, we believe
that faster injection rates play a major role in the incidence and severity of IVC reflux. Further
research is needed to understand the clinical significance of this sign.
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Keywords
reflux of CT, IVC