Abdominal CT Perfusion: Effects of Breath Control Technique

Abdominal CT Perfusion: Effects of Breath Control Technique Poster No.: C-0068 Congress: ECR 2014 Type: Scientific Exhibit Authors: T. Yoshikawa, T. Kanda, Y. Ohno, Y. Fujisawa, N. Negi, M. 1 1 2 1 1 1 3 1 1 1 2 Nishio, H. Koyama, K. Sofue, K. Sugimura ; Kobe/JP, Tokyo/ 3 JP, Otawara-Shi/JP Keywords: Hemodynamics / Flow dynamics, Technology assessment, Contrast agent-intravenous, Computer Applications-3D, CTQuantitative, Spleen, Pancreas, Liver DOI: 10.1594/ecr2014/C-0068 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 16

Aims and objectives BACKGROUND CT Perfusion (CTP) is reportedly useful for evaluation of liver damage or severity of hepatic fibrosis associated with chronic liver disease, prediction of tumor response to therapies, and evaluation of hepatic perfusion changes after surgical or radiological interventions. This method is also reportedly useful for evaluation of various diseases and conditions in other upper abdominal organs, such as pancreas, spleen, and stomach. However, some problems still remain with using this method. One of them is need for relatively long breathholding. Moreover, respiration-related motion artifacts also pose a significant problem. In some previous reports, abdominal CTP was performed under breathing without assessment of validity. Assessments for these issues are essential for effective routine clinical use of this technique. PURPOSE To assess effects of breath control technique on CT perfusion values in the abdomen Methods and materials Patients 115 patients, who were highly suspected to have intrathoracic malignancies, (male: 69, female: 39, mean age: 70.6 years old) underwent upper abdominal routine CT and CTP for preoperative assessment. All subjects gave their informed consent. 4 patients who had metastatic liver tumors were excluded from the study population because this study was aimed to assess subjects without pathological condition in the abdominal organs. 3 patients were excluded because a 20-gauge catheter could not be placed properly in the peripheral vein. Page 2 of 16

The remaining 108 patients, who did not have any indications of pathologic conditions in the upper abdomen constituted the study population and were randomly divided into two groups; breathholding group and free breathing group. Demographic features and scan parameters (FOV, CTDI, and DLP) for CT perfusion were recorded and compared. Imaging Techniques A 320 detector-row CT (Aquilion ONE, Toshiba Medical Systems, max. cranio-caudal coverage:16cm) was used. Dynamic scans were conducted 7 to 120 secs after injection of contrast medium (CM) under breathholdings or free breathing (fig. 1). The center of the scan volume was set at hepatic hilum. Scanning conditions: 80kV, 210mA Reconstruction: 0.5 mm thk x 320 slices Injection dose and rate of CM: 30ml, 5ml/sec Saline chaser: 25ml, 5ml/sec Pre- and post-contrast abdomino-pelvic scans were also acquired with additional contrast medium injection of 70ml. Misregistration Compensation & Compensation Length The CT images were then transferred to a prototype workstation (Toshiba Medical Systems), and prototype software was used for analysis. Respiratory misregistrations were compensated for first manually and then automatically with the software before perfusion analysis (fig. 2). Maximum length of manual compensation (mm) (usually z-direction) was recorded for each patient and compared between the groups (figs. 3-6). Perfusion Analysis Hepatic arterial and portal perfusion (HAP and HPP, ml/min/100ml), arterial perfusion fraction (APF, %), mean transit time (MTT, s), and distribution volume (DV, ml/100ml) were calculated using dual-input maximum slope (dms), deconvolution (ddc), and compartment model (dcm) methods using the same ROIs. Arterial perfusions (AP), MTT, and DV of pancreas, spleen, gastric wall were also calculated using single-input MS, DC, and CM (sms, sdc, scm) methods. Page 3 of 16

Oval ROIs for perfusion measurement were placed by two experienced radiologists, who made a consensus opinion, on the right liver and spleen at the level of the splenic hilum and on pancreatic body and gastric fundus on the perfusion maps and made as large as possible while avoiding large vessels and ducts. The values were compared between the groups. Images for this section: Fig. 1 Page 4 of 16

Fig. 2 Page 5 of 16

Fig. 3 Page 6 of 16

Fig. 4 Page 7 of 16

Fig. 5 Page 8 of 16

Fig. 6 Page 9 of 16

Results There was no significant difference in demographic features or scan parameters (fig. 7). Mean manual compensation length had a trend toward larger in free breathing group (13.5 ± 7.7) than breathhold (11.3 ± 7.9) (fig. 7). HAP with dcm (p<0.05) and HPPs with dms, ddc (p<0.05), and dcm (<0.005) were significantly lower in breathhold group (fig. 8). MTTs in the liver with ddc (<0.0001) and dcm (<0.0005) were significantly higher in breathhold group (fig. 8). There was no significant difference in pancreatic, splenic, or gastric perfusion values (figs. 9-11). Images for this section: Page 10 of 16

Fig. 7 Fig. 8 Page 11 of 16

Fig. 9 Page 12 of 16

Fig. 10 Page 13 of 16

Fig. 11 Page 14 of 16

Conclusion DISCUSSION Our results show that even after careful compensations for respiratory misregistrations, CT perfusion values in the liver are affected by breath control technique. Changes in portal perfusion values were possibly due to structure distortions, which made vessel tracking process in analysis difficult. CM transit time changes might be caused by intra-thoracic or inferior vena caval pressure changes. The effects of breath control technique are similar among the commonly-used three analytic methods. These changes in perfusion values should be considered in clinical use, and breath control technique should be the same throughout serial examinations. LIMITATIONS Our sample size was relatively small which restricts statistical significance, so that further studies with a larger population are needed to verify our results. We only evaluated patients without abdominal diseases. Liver stiffness can increase in proportion to severity of chronic diffuse diseases. Motion-related motion may be different between normal liver and cirrhotic one. Perfusion measurements of focal diseases such as tumors can be more affected by respiration-related motions because they are smaller in size. Further studies limited to one specific disease or condition are needed. Even with a 320-detector row CT, the cranio-caudal scanning range is limited to 16 cm, which means that the entire liver of a significant proportion of our subjects could not be covered and this may have also affected our results. CONCLUSION Even after careful compensations for respiratory misregistrations, CT perfusion values in the liver are affected by breath control technique. When measuring hepatic portal perfusion or contrast medium transit time, breathhold technique is recommended. Page 15 of 16

Personal information References 1. 2. 3. 4. 5. Lee SM, Lee HJ, Kim JI, Kang MJ, Goo JM, Park CM, Im JG. Adaptive 4D volume perfusion CT of lung cancer: effects of computerized motion correction and the range of volume coverage on measurement reproducibility. AJR Am J Roentgenol. 2013;200(6):W603-9. Jensen NK, Lock M, Fisher B, Kozak R, Chen X, Chen J, Wong E, Lee TY. Prediction and reduction of motion artifacts in free-breathing dynamic contrast enhanced CT perfusion imaging of primary and metastatic intrahepatic tumors. Acad Radiol. 2013;20(4):414-22. Kandel S, Meyer H, Hein P, Lembcke A, Rueckert JC, Rogalla P. Comparison of free breathing versus breath-hold in perfusion imaging using dynamic volume CT. Insights Imaging. 2012;3(4):323-8. Piper J, Ikeda Y, Fujisawa Y, Ohno Y, Yoshikawa T, O'Neil A, Poole I. Objective evaluation of the correction by non-rigid registration of abdominal organ motion in low-dose 4D dynamic contrast-enhanced CT. Phys Med Biol. 2012;57(6):1701-15. Chandler A, Wei W, Anderson EF, Herron DH, Ye Z, Ng CS. Validation of motion correction techniques for liver CT perfusion studies. Br J Radiol. 2012;85(1016):e514-22. Page 16 of 16