Automatic individualized contrast medium dosage during hepatic computed tomography by using computed tomography dose index volume (CTDI(vol)).

ABSTRACT

PURPOSE: To compare hepatic parenchymal contrast media (CM) enhancement during multi-detector row computed tomography (MDCT) and its correlation with volume pitch-corrected computed tomography dose index CTDI(vol)) and body weight (BW). MATERIAL AND METHODS: One hundred patients referred for standard three-phase thoraco-abdominal MDCT examination were enrolled. BW was measured in the CT suite. Forty grams of iodine was administered intravenously (iodixanol 320 mg I/ml at 5 ml/s or iomeprol 400 mg I/ml at 4 ml/s) followed by a 50-ml saline flush. CTDI(vol) presented by the CT equipment during the parenchymal examination was recorded. The CM enhancement of the liver was defined as the attenuation HU of the liver parenchyma during the hepatic parenchymal phase minus the attenuation in the native phase. RESULTS: Liver parenchymal enhancement was negatively correlated to both CTDI(vol) (r = -0.60) and BW (r = -0.64), but the difference in correlation between those two was not significant. CONCLUSION: CTDI(vol) may replace BW when adjusting CM doses to body size. This makes it potentially feasible to automatically individualize CM dosage by CT. KEY POINTS • CTDI vol is related to liver CM enhancement in the parenchymal phase. • CTDI vol provides comparable information to body weight (BW). • CTDI vol may be used when automatically adjusting CM dose for patient size.