Contrast Enhancement in Cardiovascular MDCT: Effect of Body Weight, Height, Body Surface Area, Body Mass Index, and Obesity
Kyongtae T. Bae1,
Brian A. Seeck2,
Charles F. Hildebolt3,
Cheng Tao1,
Fang Zhu1,
Masayuki Kanematsu4 and
Pamela K. Woodard3
1 Department of Radiology, University of Pittsburgh School of Medicine, 200
Lothrop St., Ste. 4895, Pittsburgh, PA 15213.
2 Division of Cardiology, Washington University School of Medicine, St. Louis,
MO.
3 Mallinckrodt Institute of Radiology, Washington University School of Medicine,
St. Louis, MO.
4 Department of Radiology, Gifu University School of Medicine, Gifu,
Japan.
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Fig. 1A —Transverse CT images are shown for patients having three body
sizes in whom different degrees of aortic attenuation were seen (image display
window width, 800 H; center, 200 H). 59-year-old woman weighing 55.8 kg and
having body mass index (BMI) of 21.1 and body surface area (BSA) of 1.59
m2 (aortic attenuation, 469 H).
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Fig. 1B —Transverse CT images are shown for patients having three body
sizes in whom different degrees of aortic attenuation were seen (image display
window width, 800 H; center, 200 H). 61-year-old man weighing 91.4 kg and
having BMI of 30.6 and BSA of 2.09 m2 (aortic attenuation, 379
H).
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Fig. 1C —Transverse CT images are shown for patients having three body
sizes in whom different degrees of aortic attenuation were seen (image display
window width, 800 H; center, 200 H). 59-year-old man weighing 154.0 kg and
having BMI of 42.4 and BSA of 2.85 m2 (aortic attenuation, 172
H).
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Fig. 3 —Plot of aortic attenuation (H) versus height (cm). Moderately
strong inverse correlation existed between aortic attenuation and body weight
(r = –0.47, p < 0.001). This indicates aortic
attenuation is reduced in taller patients. Regression formula (aortic
attenuation [H] = 882–3.3 height [cm]) indicates that, for each 10-cm
increase in height, there is decrease in enhancement of 33 H in aortic
attenuation. + = low-body mass index (BMI) group (BMI < 30), o = high-BMI
group (BMI  30). Ninety-five percent CIs (dotted fitting lines)
are fit to regression line (solid fitting line).
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Fig. 5 —Plot of aortic attenuation (H) versus body surface area (BSA)
(m2). Strongest inverse correlation (r = –0.74,
p < 0.001) existed between aortic attenuation and BSA (estimated
with Mosteller formula [42]).
This indicates aortic attenuation is reduced as BSA increases. Regression
formula was aortic attenuation (H) = 674–171.4 BSA (m2)
(p < 0.001). + = low–body mass index (BMI) group (BMI <
30), o = high-BMI group (BMI 30), Ninety-five percent CIs (dotted
fitting lines) are fit to regression line (solid fitting
line).
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Fig. 6 —Ninety-five percent mean diamond plots of aortic attenuation
(H) for low- and high-body mass index (BMI) groups. Mean aortic attenuation of
low-BMI group (352.6 ± 59.1 H) was significantly higher (p
< 0.001) than that of high-BMI group (286.2 ± 55.5 H). + = low-BMI
group (BMI < 30), o = high-BMI group (BMI 30). Horizontal line is
grand mean. Heights of diamonds represent 95% CIs and widths of diamonds are
proportional to sample sizes.
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Fig. 7 —Plot of aortic attenuation (H) versus body weight (kg) with
bivariate fits for low- and high-body mass index (BMI) groups. Regression
formula of aortic attenuation versus body weight was aortic attenuation (H) =
586–3.1 weight (kg) (p < 0.001) for low-BMI group (+,
solid fitting line) and aortic attenuation (H) = 485–1.9 weight
(kg) (p < 0.001) for high-BMI group (o, dotted fitting
line). Regression slope (H/kg) of high-BMI group (1.9 [2.6–1.1, 95%
CI]) was less steep than that for low-BMI group (3.1 [4.4–1.8]), but 95%
CIs overlap. So that regression lines can be better seen, 95% CIs are not
included in figure.
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Fig. 8 —Plot of aortic attenuation (H) versus body surface area (BSA)
(m2) with bivariate fit of low- and high-body mass index (BMI)
groups. Regression formulas of aortic attenuation versus BSA were aortic
attenuation (H) = 706–187 BSA (m2) (p < 0.001)
for low-BMI group (+, solid fitting line) and aortic attenuation (H)
= 627–151.0 BSA (m2) (p < 0.001) for high-BMI
group (o, dotted fitting line). Note that these two regression lines
are more closely approximated than two regression lines in
Figure 7. This suggests that
discrepancy between high- and low-BMI groups in decline rate of aortic
attenuation was less pronounced with BSA than with body weight.
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Copyright © 2008 by the American Roentgen Ray Society.
= –0.74, p < 0.001). This
indicates aortic attenuation is reduced in heavier patients. Regression
formula (aortic attenuation [H] = 520–2.2 weight [kg]) indicates that
1.0 mL/kg (e.g., 75 mL for a 75-kg patient) of 350 mg I/mL contrast medium is
required to achieve aortic attenuation of 355 H. + = low-body mass index (BMI)
group (BMI < 30), o = high-BMI group (BMI 