Evaluation of a body mass index-adapted protocol for low-dose 64-MDCT coronary angiography with prospective ECG triggering.
OBJECTIVE
Because an increase in body mass index (weight in kilograms divided by height squared in meters) confers higher image noise at coronary CT angiography, we evaluated a body mass index-adapted scanning protocol for low-dose 64-MDCT coronary angiography with prospective ECG triggering.


METHODS
One hundred one consecutively registered patients underwent coronary CTA with prospective ECG triggering with a fixed contrast protocol (80 mL of iodixanol, 50-mL saline chaser, flow rate of 5 mL/s). Tube voltage (range, 100-120 kV) and current (range, 450-700 mA) were adapted to body mass index. Attenuation was measured, and contrast-to-noise ratio was calculated for the proximal right coronary artery and left main coronary artery. Image noise was determined for each patient as the SD of attenuation in the ascending aorta.


RESULTS
Body mass index ranged from 18.2 to 38.8, and mean effective radiation dose from 1.0 to 3.2 mSv. There was no correlation between body mass index and image noise (r = 0.11, p = 0.284), supporting the validity of the body mass index-adapted scanning protocol. However, body mass index was inversely correlated with vessel attenuation (right coronary artery, r = -0.45, p < 0.001; left main coronary artery, r = -0.47, p < 0.001) and contrast-to-noise ratio (right coronary artery, r = -0.39, p < 0.001; left main coronary artery, r = -0.37, p < 0.001).


CONCLUSIONS
Use of the proposed body mass index-adapted scanning parameters results in similar image noise regardless of body mass index. Increased bolus dilution due to larger blood volume may account for the decrease in contrast-to-noise ratio and vessel attenuation in patients with higher body mass index, but the contrast bolus was not adapted to body mass index in this study.
Tatsugami
Fuminari
F
Department of Medical Radiology and the Cardiovascular Center, University Hospital Zurich, Raemistrasse 100, NUK C 32, CH-8091 Zurich, Switzerland.
Husmann
Lars
L
Herzog
Bernhard A
BA
Burkhard
Nina
N
Valenta
Ines
I
Gaemperli
Oliver
O
Kaufmann
Philipp A
PA
D000328:Adult; D000368:Aged; D015992:Body Mass Index; D002985:Clinical Protocols; D003287:Contrast Media / Q000008:administration & dosage; D017023:Coronary Angiography / Q000379:methods*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014283:Triiodobenzoic Acids / Q000008:administration & dosage
D003287:Contrast Media; D014283:Triiodobenzoic Acids; C044834:iodixanol