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Reflux of Contrast Medium into the Inferior Vena Cava
on Computerized Tomographic Pulmonary Angiography
Alerting for Cardiac Diseases
Poster No.:
C-0702
Congress:
ECR 2012
Type:
Scientific Exhibit
Authors:
G. Aviram, D. Cohen, A. Steinvil, S. Berliner, O. Rogowski; TelAviv/IL
Keywords:
Hemodynamics / Flow dynamics, Diagnostic procedure, CTAngiography, Thorax, Cardiac
DOI:
10.1594/ecr2012/C-0702
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Purpose
The aim of the present study was to investigate the prevalence, severity, associated
diagnoses and eventual prognostic significance of reflux of contrast medium into the IVC
in a large cohort of patients who underwent CTPA.
The number of computerized tomographic pulmonary angiographic (CTPA) examinations
performed for evaluating patients presenting with acute dyspnea has been growing
exponentially during recent years, with a relatively low prevalence (sometimes even
less than 10%) of findings consistent with the suspected diagnosis of acute pulmonary
1
embolism (PE) .
Reflux of contrast medium from the right atrium to the inferior vena cava (IVC) and hepatic
veins during the first pass of the injected bolus of contrast medium is often present on
CTPA. Only a few preliminary small series have described this finding in association with
right heart failure
2-5
.
The aim of the present study was to investigate the prevalence, severity, associated
diagnoses and eventual prognostic significance of reflux of contrast medium into the IVC
in a large cohort of patients who underwent CTPA.
We considered that these imaging findings might serve as a pathophysiological marker
of right heart dysfunction, thus tapping information obtained by the radiologist to help
explain the patient's clinical presentation.
Images for this section:
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Fig. 1: Example of a severe refulx of contrast on CT pulmonary angiography
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Methods and Materials
Study population
We evaluated 1065 consecutive CTPA studies performed in 1027 patients between
January 1, 2007 and January 7, 2008.
The patients' chartsgender and age, were reviewed for the reason for referral to
CTPA scan, final diagnoses during the index hospitalization, background and co-morbid
conditions. Information on mortality was collected from the database of the country's
Ministry of Internal Affairs.
CT Acquisition
All study patients were scanned by a multi-detector CT scanner with 16 or 64 detector
rows, according to our routine non-electrocardiographic (ECG)-gated PE protocol , with
injections of contrast medium comprised of 80-100 mL of iodinated contrast material
at rates of 3-4 mL/sec. All scans were obtained in a caudal-cranial direction covering
the chest from the lung bases to the thoracic inlet at end-of-inspiration during a single
breath#hold.
CT Assessment
The CT scans were reviewed by two radiologists who were unaware of the patient's
clinical history, results of other imaging techniques, and outcome.
The severity of reflux of contrast medium into the IVC and the hepatic veins was graded
5
from the axial images on a scale of 1-6 as described by Groves et al . (Fig. 2-7): 1 = no
reflux into the IVC, 2 = a trace of reflux into the IVC only, 3 = reflux into the IVC but not the
hepatic veins, 4 = reflux into the IVC and opacifying the proximal hepatic veins, 5 = reflux
into the IVC and opacifying mid#part of the hepatic veins, and 6 = reflux into the IVC
and opacifying the distal hepatic veins. These six grades of reflux were reduced to three
groups for statistical analyses: no reflux (grade 1), mild reflux (grades 2-3) and extensive
reflux (grades 4-6). Grading of reflux of contrast medium into the IVC was performed
separately by the two radiologists in the first 500 consecutive CTPA in order to assess
interobserver variation.
Statistical Analysis
Data were summarized as mean±standard deviation (SD) for continuous variables, and
as number of individuals for categorical variables. These clinical data and mortality
data were correlated with the severity of reflux. Kappa was calculated in order to
measure agreement between the two independent observers for grading the extent of
reflux. Comparison of frequencies between the groups of reflux grades was by chi-
Page 4 of 16
square statistics. Univariate and multivariate logistic regression models were used to
calculate the odds ratio (OR) for having extensive reflux in each diagnosis. We used
Cox proportional hazard models to evaluate the hazard ratios (HR) of severe reflux for
the outcome of mortality. All the above analyses were considered significant at P<0.05
(two-tailed). The SPSS statistical package was used to perform all statistical evaluations
(SSPS Inc., Chicago, IL, USA).
Images for this section:
Fig. 2: Reflux grade 1 = no reflux into the IVC
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Fig. 3: Reflux grade 2 = a trace of reflux into the IVC only
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Fig. 4: reflux grade 3 = reflux into the IVC but not the hepatic veins
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Fig. 5: Reflux grade 4 = reflux into the IVC and opacifying the proximal hepatic veins
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Fig. 6: Reflux grade 5 = reflux into the IVC and opacifying mid part of the hepatic veins
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Fig. 7: Reflux grade 6 = reflux into the IVC and opacifying the distal hepatic veins
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Results
The final study group included 967 CTPA scans of 367 males (38%) and 600 females
(62%) whose mean age was 62±20 years (range 17-103).
The two most common reasons for referral were symptoms of dyspnea and/or low oxygen
saturation (763 CTPA, 76.1%) and chest pain (116 CTPA, 11.6%).
PE was diagnosed in 17% of patients, while infection and oncologic diseases were the
most frequent acute final diagnoses, (Table 1).
There were 480 patients (49.6%) with no evidence of reflux (grade 1), 310 (32.1%) with
mild reflux (grade 2-3), and 177 (18.3%) with extensive reflux into the IVC and the hepatic
veins (grade 4-6).
Tables 2-4 present the number and percentage of the individuals with each grade of
reflux and the age-adjusted odds ratio (OR) and 95% confidence interval (CI) for having
extensive reflux for each diagnosis. Advanced age, most cardiac diagnoses and obesity
were associated with an increased prevalence and odds for having extensive reflux. On
the other hand, none of the pulmonary diagnoses were associated with extensive reflux,
while an oncologic diagnosis was associated with low prevalence of reflux.
Table 5 presents the multivariate logistic regression model: pulmonary hypertension, a
history of congestive heart failure (CHF), chronic atrial fibrillation (CAF), and acute PE
had significant independent associations with extensive reflux.
Three-hundred fifty-nine (37.1%) patients died during a median follow-up of 40 months
(range 0-50 months) following the performance of the CTPA scan.
Mortality analysis using Cox proportional hazard models revealed that a reflux grade of
4-6 was associated with increased mortality, with a crude HR (95% CI) of 1.42 (1.10 1.83), P=0.007.
The multivariate analysis, however, showed that this association was non-significant
following adjustment for age. As such, a grade 4-6 reflux is not an independent predictor
of mortality, but rather a finding which is associated with morbidity that is more prevalent
in older patients.
Interobserver agreement between the two readers for reflux grading was good
(kappa=0.77).
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Images for this section:
Table 1: The baseline characteristics of the study cohort, including final diagnoses during
the index hospitalization, background and co-morbid conditions
Table 2: Reflux grade and odds ratio for extensive reflux according to age, gender and
PE status
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Table 3: Reflux Grade According to Patients' Cardiac Diagnoses
Table 4: Reflux Grade According to Patients' Non-Cardiac Diagnoses
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Table 5: Logistic Regression for Extensive Reflux of Age, Gender, Obesity and
Pulmonary Embolism Status
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Conclusion
Pulmonary hypertension, CHF, CAF, and PE emerged as being the most frequent
diagnoses associated with the highest grade of reflux.
The common denominator of all these diagnoses is the possible existence of congestion
at the entrance to the right atrium.
The primary contribution of the present study is the singling out of cardiac conditions as
the main determinants of contrast medium reflux into the IVC as opposed to a relatively
large number of other clinical conditions, including pulmonary diseases, which can be
encountered in a population of patients who have signs and symptoms justifying their
referral to CTPA
We postulate that the contrast column created by the reflux to the IVC can serve as a
radio-physiological measure similar to jugular venous pressure assessment on physical
examination. As such, it can alert clinicians to the presence of congestion at the entrance
to the right atrium which is producing the backflow of contrast material into the IVC.
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Personal Information
Corresponding author: Galit Aviram, MD, Department of Radiology, Tel Aviv Medical
Center, 6 Weizman Street, Tel Aviv 64239, Israel. Telephone: +972#3#6973504, Fax:
+972#3#6974659, E#mail: [email protected]
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