Comparison of high-resolution C-arm cone-beam CT imaging and conventional 3D rotational angiography for the better microvascular visualization

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1 Comparison of high-resolution C-arm cone-beam CT imaging and conventional 3D rotational angiography for the better microvascular visualization Poster No.: C-1040 Congress: ECR 2016 Type: Scientific Exhibit Authors: Y. Tachibana, T. Ishida, K. Amakawa, M. Mori, S. Tateishi, H. ohura, R. Miyajima, S. Orita, T. Tsumoto; Keywords: DOI: Fistula, Arteriovenous malformations, Aneurysms, Computer Applications-3D, Arterial access, Cone beam CT, Catheter arteriography, Neuroradiology brain, Interventional vascular, Head and neck /ecr2016/C-1040 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. Page 1 of 16

2 Aims and objectives As high-resolution 3D imaging C-arm cone-beam computed tomography (CBCT) has been further developed in interventional radiology, it has become possible to provide more precise information on the microvasculature. Recently, high resolution C-arm cone beam CT (HRCBCT) was developed to visualize the microvasculature and evaluate the stent lumen (Vaso CT, Philips Healthcare, Best, Netherlands). However, few reports have focused on the advantages of HRCBCT imaging over conventional 3D rotational angiography (3DRA). The purpose of this study was to reveal the optimal 3D imaging for microvascular visualization by comparison of the quality of images using HRCBCT and 3DRA. Methods and materials Scanning and image reconstruction Image quality phantoms were scanned using HRCBCT and 3DRA in the same field of view (FOV; 8 inches) and same size matrix for evaluation of a feasible approach. Both systems were equipped with the same angiography system with a flat panel detector (Allura Clarity FD 20/20, Philips Healthcare, Best, Netherlands), and the acquisition protocols and postprocessing algorithms were embedded in the system (Fig.1). The HRCBCT imaging was conducted at a rate of 30 frames/s, total rotation time of 20 s, focus size of 0.4 mm, 620 frames total, 240 angle using a 1,024 1,024 pixel matrix detector with an 8-in FOV, and a fixed 80 kv tube voltage. The conventional 3DRA imaging was conducted at a rate of 30 frames/s, total rotation time of 4.1 s, focus size of 0.7 mm, 120 frames total, 240 angle using a 1,024 1,024 pixel matrix detector with an 8-in FOV and an 88 kv tube voltage. Then, HRCBCT images were reconstructed using stent mode as an optimal kernel, voxel size of and maximum spatial resolution matrix, and 3DRA images were reconstructed in very sharp mode as an optimal kernel, voxel size of 512 3, and maximum spatial resolution matrix using a 3D workstation (Xtravision; Philips Healthcare). Finally, these images were rendered with a slice thickness of 5.0 mm using Ziostation2 (Ziosoft, Japan) at the medical imaging workstation for evaluation of the following four image qualities. Page 2 of 16

3 Modulation transfer function Modulation transfer function (MTF) was measured using a laboratory-made 20 cm diameter water phantom with a 0.2 mm# copper wire at the center. Each signal value of rendered images was measured by ImageJ, which is a Java-based application for analyzing images, and the MTF was obtained by the wire method (Fig. 2). Noise power spectrum A Catphan phantom (Phantom Laboratory, Salem, NY) was used for measurement of the noise power spectrum (NPS). The phantom consisted of various cylindrical sections (modules), each of which was designed for a specific test. For this study, module CTP712 (uniformity section) was used. Each signal value of rendered images at the phantom center was measured, and the NPS was obtained by a one-dimensional method using numerical slit scanning (slit method) with five slit traces using a 1 30 pixel virtual slit by ImageJ (Fig. 3). Signal-to-noise ratio The signal-to-noise ratio (SNR) was calculated from the MTF and NPS. We defined it as SNR=(MTF 2 #NPS) 1/2. Contrast intensity Contrast intensity was measured using a laboratory-made 20 cm diameter water phantom that has 2 mm diameter silicon tubes filled with diluted contrast medium (Omnipaque 300; Iohexol, 300 mgi/ml) placed at the center of the phantom (Fig. 4). The dilution factors of the tubes were: 1 (100% undiluted contrast medium), 1/2 (50% concentration), 1/3(33%), 1/5 (20%), 1/7 (14.3%), 1/10(10%). Signal values of the tubes in rendered images were measured using Ziostation2. Images for this section: Page 3 of 16

4 Fig. 1: This figure shows the angiography system with the flat panel detector (Allura Clarity FD 20/20, Philips Healthcare, Best, Netherlands) and experimental configuration for MTF, NPS, and contrast intensity. Page 4 of 16

5 Fig. 2: Modulation transfer function (MTF) was measured using a laboratory-made 20 cm diameter water phantom with a 0.2 mm# copper wire at the center. Page 5 of 16

6 Fig. 3: signal value of rendered images at the phantom center was measured, and the NPS was obtained by a one-dimensional method. Page 6 of 16

7 Fig. 4: Contrast intensity was measured using a laboratory-made 20 cm diameter water phantom that has 2 mm diameter silicon tubes filled with diluted contrast medium. Page 7 of 16

8 Results Modulation transfer function The results of the MTF on HRCBCT images and 3DRA images are shown in Fig. 5. The MTF values of HRCBCT images were superior to those of 3DRA images in the high frequency range. Each 10% point of the modulation-transfer-function (10% MTF) was 2.23 cycles/mm and 1.81 cycles/mm, respectively. The 10% MTF of HRCBCT images were 1.23 times higher than 3DRA images. Noise power spectrum The results of the NPS on HRCBCT images and 3DRA images are shown in Fig. 6. Although both NPS declined with increasing frequency, the graphic form of the NPS from HRCBCT images was quite different from that from 3DRA images. The NPS of 3DRA images was considerably higher than that of HRCBCT in the low frequency range, but this was reversed in the high frequency range. Signal-to-noise ratio The results of the SNR on HRCBCT images and 3DRA images are shown in Fig. 7. The HRCBCT image showed a higher SNR than the 3DRA image in all spatial frequency domains. Contrast intensity The contrast intensities of HRCBCT and 3DRA images are shown in Fig. 8. The contrast intensity of the HRCBCT images was constantly higher than that of the 3DRA images depending on the concentration of contrast medium, 1.3 times at maximum. Images for this section: Page 8 of 16

9 Fig. 5: The results of the MTF on HRCBCT images and 3DRA images Page 9 of 16

10 Fig. 6: The results of the NPS on HRCBCT images and 3DRA images Page 10 of 16

11 Fig. 7: The results of the SNR on HRCBCT images and 3DRA images Page 11 of 16

12 Fig. 8: The results of contrast intensity on HRCBCT images and 3DRA images Page 12 of 16

13 Conclusion The HRCBCT images had higher resolution than 3DRA images in terms of MTF, and SNR showed better visibility. Furthermore, HRCBCT images had higher contrast intensity than 3DRA (Fig. 9).To validate the advantages of HRCBCT imaging over 3DRA, clinical images of one case using both imaging systems are shown. An unruptured aneurysm at the bifurcation of the left MCA main stem (M1) and secondary trunks (M2) of a 66- year-old woman are shown in Fig. 10. The microvasculature of the cerebral arteries and derived from an unruptured aneurysm were more visible in the HRCBCT images than in 3DRA images. In conclusion, HRCBCT provides more precise images than 3DRA and is optimal 3D imaging for microvascular visualization. Images for this section: Fig. 9: The phantom images used for evaluation of the MTF, NPS, and contrast intensity. Page 13 of 16

14 Fig. 10: One cases of clinical images compared with HRCBCT and 3DRA Page 14 of 16

15 Personal information Yuji Tachibana, Radiological Technologist, Kyushu Medical Center, Department of Radiology, Clinical Reserch Institute, Fukuoka, Japan, References 1. Thomas F Flood. Quantitative analysis of high-resolution, contrast-enhanced, conebeam CT for the detection of intracranial in-stent hyperplasia, neurintsurg N.V. Patel, M.J. Gounis, A.K. Wakhloo, N. Noordhoek, J. Blijd, D. Babic, D. Takhtani, S.-K. Lee, A. Norbash, Contrast-Enhanced Angiographic Cone-Beam CT of Cerebrovascular Stents: Experimental Optimization and Clinical Application, AJNR Am J Neuroradiol 2011;32: Rossmann.K. Point Spread-Function, Line Spread Function, and Modulation Transfer Function, Radiology 93: , A.Kayugawa, M.Ohkubo, S.WADA. Accurate determination of CT point-spreadfunction with high precision. Jouenal of Applied Clinical Medical Physics , Boedeker.KL, Cooper.VN, McNitt-Gray. MF. Application of the noise power spectrum in modern diagnostic MDCT, part #.Measurement of noise power spectra and noise equivalent quanta, Phys. Med. Biol. 2007; 52(14): Page 15 of 16

16 6. Boedeker,K, McNitt-Gray. Application of the noise power spectrum in modern diagnostic MDCT, part #.Noise power spectra and signal to noise, Phys. Med. Biol. 2007; 52(14): Samei.E. Performance of Digital Radiographic Detectors: Quantification and Assessment Method, Advances in Digital Radiography: RSNA Categorical Course in Diagnostic Radiology Physics 2003;pp T.Hara, K.Ichikawa, S.Sanada, Y.Ida. Image quality dependence on in-plane positions and directions for MDCT images, Eur. J. Radiology. July 2010 volume75, Issue 1, Pages Page 16 of 16