Aortic and hepatic contrast enhancement with abdominal 64-MDCT in pediatric patients: effect of body weight and iodine dose.

OBJECTIVE The purpose of our study was to retrospectively evaluate the effect of body weight and iodine dose on aortic and hepatic contrast enhancement in pediatric patients who underwent 64-MDCT of the abdomen and pelvis. MATERIALS AND METHODS Eighty-seven consecutive pediatric patients (50 boys and 37 girls; median age, 12.1 years; age range, 3.8-17.6 years) underwent standard abdominopelvic CT with a 64-MDCT scanner. Contrast medium (350 mg I/mL) was injected using a power injector at 2 mL/s followed by 15-20 mL of saline flush. According to our CT protocol, the volume of administered contrast medium was approximately 1.8 mL/kg of body weight, up to the maximum volume of 80 mL. CT scanning was initiated 60 seconds after the start of the contrast medium injection. CT attenuations of the aorta and liver were measured. For each patient, the injected contrast medium iodine mass per body weight index (g I/kg) (hereafter, iodine mass body index) was calculated. Linear regression analysis was performed between iodine mass body index and aortic and hepatic attenuations. RESULTS A wide range of patient weights (19-82 kg; mean, 48.6 kg [95% CI, 45.3-51.9 kg]) and contrast volumes (30-80 mL; median, 80.0 mL) were observed. The median attenuations were 149.0 HU (141.0-160.0 HU) for the aorta and 113.5 HU (109.5-120.0 HU) for the liver. Moderately high correlations were observed between iodine mass body index and aortic (Spearman's rho [r(s)] = 0.60 [0.45-0.72]; p < 0.001) and hepatic (r(s) = 0.60 [0.42-0.70]; p < 0.001) attenuations. The regression formulae for aortic attenuation (58.4 + 176.3 x iodine mass body index [p < 0.001]) and hepatic attenuation (58.7 + 108.5 x iodine mass body index [p < 0.001]) indicate that 1.5 and 1.8 mL/kg (350 mg I/mL) of contrast media are required to achieve 116 and 127 HU, respectively, of contrast-enhanced attenuation in the liver. CONCLUSION In our study, using abdominal 64-MDCT in pediatric patients, we found that approximately 1.5 mL/kg, or 0.525 g I/kg, yields 116 HU of hepatic attenuation or 50-55 HU of hepatic enhancement.

[1]  C. Beam,et al.  Contrast material for combined abdominal and pelvic CT: can cost be reduced by increasing the concentration and decreasing the volume? , 1993, AJR. American journal of roentgenology.

[2]  T. Murakami,et al.  Effects of injection rates of contrast material on arterial phase hepatic CT. , 1998, AJR. American journal of roentgenology.

[3]  W A Kalender,et al.  Bolus geometry and dynamics after intravenous contrast medium injection. , 1984, Radiology.

[4]  B. Herts,et al.  Power injection of contrast media using central venous catheters: feasibility, safety, and efficacy. , 2001, AJR. American journal of roentgenology.

[5]  Katsuyoshi Ito,et al.  Hepatic enhancement in multiphasic contrast-enhanced MDCT: comparison of high- and low-iodine-concentration contrast medium in same patients with chronic liver disease. , 2004, AJR. American journal of roentgenology.

[6]  S S Sagel,et al.  Dynamic contrast-enhanced CT of the liver: comparison of contrast medium injection rates and uniphasic and biphasic injection protocols. , 1993, Radiology.

[7]  J. Heiken,et al.  Dynamic incremental CT: effect of volume and concentration of contrast material and patient weight on hepatic enhancement. , 1995, Radiology.

[8]  K. Bae,et al.  Peak contrast enhancement in CT and MR angiography: when does it occur and why? Pharmacokinetic study in a porcine model. , 2003, Radiology.

[9]  J A Brink,et al.  Aortic and hepatic peak enhancement at CT: effect of contrast medium injection rate--pharmacokinetic analysis and experimental porcine model. , 1998, Radiology.

[10]  C. Reinhold,et al.  Effect of rate of contrast medium injection on hepatic enhancement at CT. , 1996, Radiology.

[11]  J C Gardner,et al.  Hepatic helical CT: effect of reduction of iodine dose of intravenous contrast material on hepatic contrast enhancement. , 1995, Radiology.

[12]  D. Frush,et al.  From the RSNA refresher courses. Challenges of pediatric spiral CT. , 1997, Radiographics : a review publication of the Radiological Society of North America, Inc.

[13]  P. Taroni,et al.  Does iodine concentration affect the diagnostic efficacy of biphasic spiral CT in patients with hepatocellular carcinoma? , 2005, Abdominal Imaging.

[14]  R C Nelson,et al.  Contrast-enhanced spiral CT of the liver: effect of different amounts and injection rates of contrast material on early contrast enhancement. , 1994, AJR. American journal of roentgenology.

[15]  M Kormano,et al.  Dynamic contrast enhancement of the upper abdomen: effect of contrast medium and body weight. , 1983, Investigative radiology.

[16]  K. Bae,et al.  Test-bolus versus bolus-tracking techniques for CT angiographic timing. , 2005, Radiology.

[17]  M. Tillich,et al.  High-Concentration Contrast Media in Multiphasic Abdominal Multidetector-Row Computed Tomography: Effect of Increased Iodine Flow Rate on Parenchymal and Vascular Enhancement , 2005, Journal of computer assisted tomography.

[18]  M. Ambrosino,et al.  Pediatric hepatic CT: An injection protocol , 2005, Pediatric Radiology.

[19]  M. Tublin,et al.  Effect of injection rate of contrast medium on pancreatic and hepatic helical CT. , 1999, Radiology.

[20]  Charles F Hildebolt,et al.  Effect of patient weight and scanning duration on contrast enhancement during pulmonary multidetector CT angiography. , 2007, Radiology.

[21]  K. Bae,et al.  Scan and contrast administration principles of MDCT , 2005, European radiology.

[22]  K. Takeshita.  Prediction of maximum hepatic enhancement on computed tomography from dose of contrast material and patient weight: proposal of a new formula and evaluation of its accuracy. , 2001, Radiation medicine.

[23]  T. Chambers,et al.  Hepatic CT enhancement. Part I. Alterations in the volume of contrast material within the same patients. , 1994, Radiology.

[24]  T. Shimizu,et al.  Helical CT of the liver with computer-assisted bolus-tracking technology: scan delay of arterial phase scanning and effect of flow rates. , 2000, Journal of computer assisted tomography.

[25]  M Takahashi,et al.  Multiple-phase helical CT of the liver for detecting small hepatomas in patients with liver cirrhosis: contrast-injection protocol and optimal timing. , 1996, AJR. American journal of roentgenology.

[26]  D. Frush.  Technique of pediatric thoracic CT angiography. , 2005, Radiologic clinics of North America.

[27]  Nico Mollet,et al.  Intravenous contrast material administration at 16-detector row helical CT coronary angiography: test bolus versus bolus-tracking technique. , 2004, Radiology.

[28]  P. Dean,et al.  Hepatic CT contrast enhancement: effect of dose, duration of infusion, and time elapsed following infusion. , 1980, Investigative radiology.

[29]  K. Awai,et al.  Effect of contrast material injection duration and rate on aortic peak time and peak enhancement at dynamic CT involving injection protocol with dose tailored to patient weight. , 2004, Radiology.

[30]  J. Ellis,et al.  Aortic enhancement during abdominal CT angiography: correlation with test injections, flow rates, and patient demographics. , 1999, AJR. American journal of roentgenology.

[31]  S. Seltzer,et al.  A contrast agent delivery nomogram for hepatic spiral CT. , 1997, Journal of computer assisted tomography.

[32]  Y. Yamashita,et al.  16-MDCT aortography with a low-dose contrast material protocol. , 2006, AJR. American journal of roentgenology.

[33]  Kazuo Awai,et al.  Effect of contrast injection protocol with dose tailored to patient weight and fixed injection duration on aortic and hepatic enhancement at multidetector-row helical CT , 2003, European Radiology.

[34]  M. Kanematsu,et al.  Optimizing Scan Delays of Fixed Duration Contrast Injection in Contrast-Enhanced Biphasic Multidetector-Row CT for the Liver and the Detection of Hypervascular Hepatocellular Carcinoma , 2005, Journal of computer assisted tomography.

[35]  M M Walkey,et al.  Dynamic hepatic CT: how many years will it take 'til we learn? , 1991, Radiology.

[36]  M Takahashi,et al.  Abdominal helical CT: evaluation of optimal doses of intravenous contrast material--a prospective randomized study. , 2000, Radiology.

[37]  H. Forman,et al.  Hepatic spiral CT: reduction of dose of intravenous contrast material. , 1995, Radiology.

[38]  Y. Yamashita,et al.  Pancreas: patient body weight tailored contrast material injection protocol versus fixed dose protocol at dynamic CT. , 2007, Radiology.

[39]  N. Obuchowski,et al.  Use of contrast material for spiral CT of the abdomen: comparison of hepatic enhancement and vascular attenuation for three different contrast media at two different delay times. , 1995, AJR. American journal of roentgenology.

[40]  D. DeLong,et al.  Optimizing contrast-enhanced abdominal CT in infants and children using bolus tracking. , 1999, AJR. American journal of roentgenology.

[41]  T. Chambers,et al.  Hepatic CT enhancement. Part II. Alterations in contrast material volume and rate of injection within the same patients. , 1994, Radiology.

[42]  D. Frush,et al.  Effect of scan delay on hepatic enhancement for pediatric abdominal multislice helical CT. , 2001, AJR. American journal of roentgenology.

[43]  L. Berland,et al.  Comparison of contrast media injection rates and volumes for hepatic dynamic incremented computed tomography. , 1988, Investigative radiology.

[44]  E. Fishman,et al.  Dose Requirements for a Nonionic Contrast Agent for Spiral Computed Tomography of the Liver in Rabbits , 1994, Investigative radiology.

[45]  L L Berland,et al.  Effect of varying rates of low-osmolarity contrast media injection for hepatic CT: correlation with indocyanine green transit time. , 1992, Radiology.

[46]  U Joseph Schoepf,et al.  CT of coronary artery disease. , 2004, Journal of thoracic imaging.

[47]  E. Fishman,et al.  Quantitative and qualitative evaluation of volume of low osmolality contrast medium needed for routine helical abdominal CT. , 2001, AJR. American journal of roentgenology.