Contrast enhancement for whole-body screening using multidetector row helical CT: comparison between uniphasic and biphasic injection protocols.
OBJECTIVE
To investigate which is more suitable for whole-body screening with multidetector row CT (MDCT) during one breathhold, a uniphasic or biphasic injection protocol for contrast material.


METHODS
Sixty patients received a volume of 1.7 mL x weight (kg) with iopamidol 300 mg iodine/mL. The patients were randomized into two injection protocols: A) a fixed injection rate of 2.0 mL/sec with a 70 sec delay, B) administration of 80% of the contrast material in 40 sec, then administration of the remaining 20% in 20 sec with an 80 sec delay. A helical scan from the apex of the lung to the base of the pelvic cavity was performed during one breathhold. CT attenuation values of the thoracic aorta, pulmonary artery, abdominal aorta, portal vein, superior vena cava (SVC), suprarenal and infrarenal inferior vena cava (IVC), liver, and pancreas were measured. Two radiologists visually assessed the degree enhancement of the IVC. In addition, the two radiologists visually assessed artifacts caused by contrast material in the subclavian vein and SVC using a four-point scale.


RESULTS
Enhancement of the SVC in protocol A was significantly better than that in protocol B (p=0.04). Enhancement of the infrarenal IVC and liver in protocol B was significantly better than that in protocol A (p<0.01, p<0.01). Renal enhancement in protocol B was significantly better than that in protocol A (p=0.02). In all patients with both protocols A and B, enhancement of the suprarenal IVC was visually graded as acceptable or good. In all patients with protocol B, enhancement of the infrarenal IVC was graded as acceptable or good. In only 2/3 of patients with protocol A, enhancement of the infrarenal IVC was graded as acceptable or good. There was no significant difference in artifacts in the subclavian vein between the two protocols (p=0.77). Artifacts in the SVC in protocol B were significantly fewer than those in protocol A (p<0.01).


CONCLUSIONS
Protocol B was more suitable for whole-body screening than protocol A, because of better enhancement of the liver and infrarenal IVC and fewer artifacts in the SVC.
Awai
Kazuo
K
Department of Diagnostic Radiology, Kumamoto University Graduate School of Medical Sciences, 1-1-1 Honjyo, Kumamoto 860-8556, Japan.
Imuta
Masanori
M
Utsunomiya
Daisuke
D
Nakaura
Takeshi
T
Shamima
Sultana
S
Kawanaka
Koichi
K
Hori
Shinichi
S
Yamashita
Yasuyuki
Y
D016477:Artifacts; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007275:Injections, Intravenous / Q000379:methods*; D007479:Iopamidol / Q000008:administration & dosage; D007668:Kidney / Q000000981:diagnostic imaging; D008099:Liver / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013350:Subclavian Vein / Q000000981:diagnostic imaging; D013997:Time Factors; D036542:Tomography, Spiral Computed / Q000379:methods; D014683:Vena Cava, Superior / Q000000981:diagnostic imaging
D003287:Contrast Media; D007479:Iopamidol