Koji Nakaya1,2,3, Masahisa Onoguchi4, Yoshihiro Nishimura3, Keisuke Kiso3, Hideki Otsuka5, Yoshifumi Nouno3, Takayuki Shibutani1, Eisuke Yasuda2. 1. Department of Quantum Medical Technology, Graduate School of Medical Sciences, Kanazawa University, Ishikawa, Japan. 2. Department of Radiological Technology, Faculty of Health Science, Suzuka University of Medical Science, Mie, Japan. 3. Department of Radiology and Nuclear Medicine, National Cerebral and Cardiovascular Center Hospital, Osaka, Japan; and. 4. Department of Quantum Medical Technology, Graduate School of Medical Sciences, Kanazawa University, Ishikawa, Japan onoguchi@staff.kanazawa-u.ac.jp. 5. Department of Medical Imaging/Nuclear Medicine, Tokushima University Graduate School, Tokushima, Japan.
Abstract
Because it suppresses attenuation artifacts from the diaphragm, prone SPECT is suitable for evaluating the cardiac inferior wall. A solid-state dedicated cardiac camera allows upright imaging, which can also be used to avoid attenuation artifacts from the diaphragm. We compared prone and upright imaging for inferior wall evaluation using 201TlCl myocardial perfusion SPECT (MPS). Methods: The study targeted 45 patients. The prone imaging group included 23 subjects who underwent additional prone imaging because supine imaging indicated that the inferior wall had reduced uptake. The upright imaging group included 22 subjects who, in the past, had shown reduced uptake in the inferior wall during supine imaging. Using the MPS stress images and analysis software, we created a polar map showing the incorporation of the radioisotope throughout the whole of the myocardium; this polar map was then classified into 17 segments. The percentage uptake ratios of the inferior/anterior wall were calculated for the prone and upright acquisitions. These ratios were used as the ratio of percentage uptake in each segment of the anterior wall to percentage uptake in each segment of the inferior wall. In addition, 6 reviewers visually evaluated the uniformity within the inferior wall for both the prone and the upright imaging. Results: There was a significant difference in percentage uptake ratios between the prone and upright images in segments 4/1 (basal inferior/basal anterior; P < 0.05), 11/12 (mid inferolateral/mid anterolateral; P < 0.001), and 15/13 (apical inferior/apical anterior; P < 0.05). There were no significant differences between the prone and upright images in visual evaluations of uniformity within the inferior wall. Conclusion: In comparison with upright imaging, prone imaging has a higher rate of suppression of attenuation artifacts from the diaphragm. However, this difference does not seem to affect the images visually. Therefore, upright and prone imaging can be used interchangeably to evaluate the inferior wall.
Because it suppresses attenuation artifacts from the diaphragm, prone SPECT is suitable for evaluating the cardiac inferior wall. A solid-state dedicated cardiac camera allows upright imaging, which can also be used to avoid attenuation artifacts from the diaphragm. We compared prone and upright imaging for inferior wall evaluation using 201TlCl myocardial perfusion SPECT (MPS). Methods: The study targeted 45 patients. The prone imaging group included 23 subjects who underwent additional prone imaging because supine imaging indicated that the inferior wall had reduced uptake. The upright imaging group included 22 subjects who, in the past, had shown reduced uptake in the inferior wall during supine imaging. Using the MPS stress images and analysis software, we created a polar map showing the incorporation of the radioisotope throughout the whole of the myocardium; this polar map was then classified into 17 segments. The percentage uptake ratios of the inferior/anterior wall were calculated for the prone and upright acquisitions. These ratios were used as the ratio of percentage uptake in each segment of the anterior wall to percentage uptake in each segment of the inferior wall. In addition, 6 reviewers visually evaluated the uniformity within the inferior wall for both the prone and the upright imaging. Results: There was a significant difference in percentage uptake ratios between the prone and upright images in segments 4/1 (basal inferior/basal anterior; P < 0.05), 11/12 (mid inferolateral/mid anterolateral; P < 0.001), and 15/13 (apical inferior/apical anterior; P < 0.05). There were no significant differences between the prone and upright images in visual evaluations of uniformity within the inferior wall. Conclusion: In comparison with upright imaging, prone imaging has a higher rate of suppression of attenuation artifacts from the diaphragm. However, this difference does not seem to affect the images visually. Therefore, upright and prone imaging can be used interchangeably to evaluate the inferior wall.