Simulation of aortic peak enhancement on MDCT using a contrast material flow phantom: feasibility study.

OBJECTIVE The objective of our study was to develop a flow phantom simulating aortic peak enhancement after the injection of contrast material on CT and to investigate the validity of the flow phantom by comparing the time-enhancement curves obtained for the flow phantom and humans. MATERIALS AND METHODS We developed a flow phantom simulating the enhancement pattern of the aorta after the injection of contrast material. In protocols 1, 2, and 3 of the phantom study, 90, 102, and 150 mL of iohexol, respectively, was administered over 35 sec. In protocol 4, 102 mL of iohexol was administered over 25 sec. In phantom protocols 1', 2', and 3', the dose and contrast injection duration were the same as in protocols 1, 2, and 3; however, saline (10 mL) was injected during the 20 sec after contrast delivery. In the human study, 20 patients were randomized into four groups: Groups A, B, and C received 1.5, 1.7, and 2.5 mL of iohexol per kilogram of body weight, respectively, over 35 sec; and group D received 1.7 mL/kg over 25 sec. In patient groups A, B, C, and D, phantom protocols 1, 2, 3, and 4 were used, respectively. Single-level serial CT scans were obtained using a 16-MDCT scanner on the simulated and real aortas after the injection of contrast material. Time-enhancement curves of simulated and real aortas were generated, and aortic peak times and aortic peak enhancement values were calculated. RESULTS Aortic peak enhancement and aortic peak times in protocols 1-4 and 1'-3' of the phantom study were 2-8% larger and 6-18% longer, respectively, than in the corresponding patient study. The shape of the time-enhancement curves before aortic peak time in protocols 1-3 and 1'-3' of the phantom study closely resembled that of the corresponding patient study. After the aortic peak time, the shape of time-enhancement curves in protocols 1, 2, and 3 of the phantom study was different from the corresponding patient study; however, it was similar in phantom protocols 1'-3' and the corresponding patient study. In all four phantom protocols, the difference between maximal and minimal aortic peak enhancement was less than the SD of the corresponding patient study. CONCLUSION The level of peak aortic enhancement and the time to peak aortic enhancement were similar in the phantom and human studies when we used our different contrast injection protocols for MDCT.

[1]  A. Leung,et al.  Computed tomographic angiography: historical perspective and new state-of-the-art using multi detector-row helical computed tomography. , 1999, Journal of computer assisted tomography.

[2]  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.

[3]  T. Mosher,et al.  Thoracic spiral CT: delivery of contrast material pushed with injectable saline solution in a power injector. , 1997, Radiology.

[4]  J P Heiken,et al.  Multiphasic injection method for uniform prolonged vascular enhancement at CT angiography: pharmacokinetic analysis and experimental porcine model. , 2000, Radiology.

[5]  T. Winter,et al.  Using a saline chaser to decrease contrast media in abdominal CT. , 2003, AJR. American journal of roentgenology.

[6]  J A Brink,et al.  Aortic and hepatic contrast medium enhancement at CT. Part II. Effect of reduced cardiac output in a porcine model. , 1998, Radiology.

[7]  Y. Yamashita,et al.  Prediction of aortic peak enhancement in monophasic contrast injection protocols at multidetector CT: phantom and patient studies , 2007, Radiation Medicine.

[8]  Filippo Cademartiri,et al.  Non-invasive 16-row multislice CT coronary angiography: usefulness of saline chaser , 2004, European Radiology.

[9]  D. Fleischmann,et al.  Accuracy of Predicting and Controlling Time-Dependent Aortic Enhancement from a Test Bolus Injection , 2001, Journal of computer assisted tomography.

[10]  D. Fleischmann,et al.  Mathematical analysis of arterial enhancement and optimization of bolus geometry for CT angiography using the discrete fourier transform. , 1999, Journal of computer assisted tomography.

[11]  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.

[12]  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.

[13]  G. Rubin,et al.  Techniques for performing multidetector-row computed tomographic angiography. , 2001, Techniques in vascular and interventional radiology.

[14]  M. Prokop.  Protocols and future directions in imaging of renal artery stenosis: CT angiography. , 1999, Journal of computer assisted tomography.

[15]  G. Rubin.  CT angiography of the thoracic aorta. , 2003, Seminars in roentgenology.

[16]  M. Tillich,et al.  Abdominal Multidetector Row Computed Tomography: Reduction of Cost and Contrast Material Dose Using Saline Flush , 2003, Journal of computer assisted tomography.

[17]  P. Colletti.  Cardiac imaging 2006. , 2006, AJR. American journal of roentgenology.

[18]  M. Prokop.  Multislice CT angiography. , 2000, European journal of radiology.

[19]  C. Némoz,et al.  Using thoracic helical CT to assess iodine concentration in a small volume of nonionic contrast medium during vascular opacification: a prospective study. , 2000, AJR. American journal of roentgenology.

[20]  J A Brink,et al.  Aortic and hepatic contrast medium enhancement at CT. Part I. Prediction with a computer model. , 1998, Radiology.

[21]  K. Bae,et al.  Uniform vascular contrast enhancement and reduced contrast medium volume achieved by using exponentially decelerated contrast material injection method. , 2004, Radiology.

[22]  R. Schoellnast,et al.  Improvement of parenchymal and vascular enhancement using saline flush and power injection for multiple-detector-row abdominal CT , 2004, European Radiology.

[23]  Yuji Itai,et al.  Contrast-Enhanced CT With Saline Flush Technique Using Two Automated Injectors: How Much Contrast Medium Does It Save? , 2002, Journal of computer assisted tomography.

[24]  Y. Shibamoto,et al.  Comparison of 2 Contrast Materials With Different Iodine Concentrations in 3-Dimensional Computed Tomography Angiography of the Hepatic Artery at Multi-Detector-Row Computed Tomography: A Randomized Study , 2007, Journal of computer assisted tomography.

[25]  G D Rubin,et al.  Improved uniformity of aortic enhancement with customized contrast medium injection protocols at CT angiography. , 2000, Radiology.

[26]  G D Rubin,et al.  Helical CT Angiography of the Thoracic Aorta , 1997, Journal of thoracic imaging.

[27]  R W Günther,et al.  Reduction of contrast material dose and artifacts by a saline flush using a double power injector in helical CT of the thorax. , 2000, AJR. American journal of roentgenology.