Abdominal Multidetector CT in Patients with Varying Body Fat Percentages: Estimation of Optimal Contrast Material Dose

Hiroshi Kondo, MD Masayuki Kanematsu, MD Satoshi Goshima, MD Yuhei Tomita, RT Toshiharu Miyoshi, RT Atsushi Hatcho, RT Noriyuki Moriyama, MD Minoru Onozuka, PhD YoshimuneShiratori, MD Kyongtae T. Bae, MD, PhD

Purpose: To determine if contrast material dose for abdominal mul­tidetector computed tomography (CT), as determined by using body weight (BW), overestimates the amount of contrast material required in heavier patients.

Materials and Methods: Institutional review committee approval and patients writ­ten informed consent were obtained. CT images of the abdomen were obtained by using 2 mL per kilogram of BW of intravenous contrast material (300 mg/mL iodine) in­jected at 4 mL/sec in 161 consecutive patients (age range, 28-90 years; mean age, 63 years; 95 men, 66 women). CT scans were initiated 45 and 150 seconds after aortic en­hancement increased by 50 HU. The patients were divided into low (37-54 kg) and high (55-75 kg) BW groups. The AHU/J, where AHU is change in CT number and I is iodine dose in grams, and adjusted maximum hepatic enhance­ment (AHU/[I/kg]) were assessed for correlation with BW, body mass index (BMI), and body fat percentage (BFP) by using linear regression.

Results: AHU/I correlated (P

Conclusion: Excessive contrast material may inadvertently be given in heavier patients when the dose is determined by patient BW. Contrast material dose may need to be tailored in individual patients by using BFP.