Published online before print September 16, 2005, 10.1148/radiol.2372041387
Object-specific Attenuation Correction at SPECT/CT in Thorax: Optimization of Respiratory Protocol for Image Registration1
Daisuke Utsunomiya, MD,
Takeshi Nakaura, MD,
Tsuyoshi Honda, MD,
Shinya Shiraishi, MD,
Seiji Tomiguchi, MD,
Koichi Kawanaka, MD,
Shoji Morishita, MD,
Kazuo Awai, MD,
Hisao Ogawa, MD and
Yasuyuki Yamashita, MD
1 From the Departments of Diagnostic Radiology (D.U., T.N., S.S., S.T., K.K., S.M., K.A., Y.Y.) and Cardiovascular Medicine (T.H., H.O.), Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan. From the 2003 RSNA Annual Meeting. Received August 10, 2004; revision requested October 14; revision received January 18, 2005; accepted February 16.
Address correspondence to D.U., Diagnostic Imaging Center, Saiseikai Kumamoto Hospital, 5-3-1 Chikami, Kumamoto-shi, Kumamoto 861-4193, Japan (e-mail: d-utsunomiya{at}skh.saiseikai.or.jp).
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Figure 1a. (a) Schematic and (b) photograph of SPECT/CT system. Position of the SPECT scanner adjacent to the multi–detector row CT scanner (MDCT) enables movement of the patient with a simple extension of the table from the CT scanner into the gantry-free SPECT scanner.
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Figure 1b. (a) Schematic and (b) photograph of SPECT/CT system. Position of the SPECT scanner adjacent to the multi–detector row CT scanner (MDCT) enables movement of the patient with a simple extension of the table from the CT scanner into the gantry-free SPECT scanner.
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Figure 2. Flowchart shows process in which CT images are used to correct attenuation on SPECT images. MLEM = maximum likelihood expectation maximization.
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Figure 3. Left: Coronal SPECT image. Right: Coronal SPECT/CT fusion image with grid overlay that shows the three reference points used to determine image registration error. Error was measured as the distance between the reference point on the SPECT image and that on the CT image, with regard to the following parameters: vertical displacement of the diaphragmatic dome (1); lateral displacement of the heart border (2); and lateral displacement of the chest wall border (3). Double white lines with opposing arrows indicate the limits of displacement.
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Figure 4a. Final attenuation-corrected short-axis cardiac sections obtained with SPECT/CT in a 32-year-old man by using three respiratory protocols and internal landmarks for registration. (a) Image acquired during postinhalation breath hold shows severe artifact that suggests decreased radiotracer uptake in the inferior wall (arrows). (b, c) Images acquired during postexhalation breath hold (b) and during free breathing (c) show no artifact.
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Figure 4b. Final attenuation-corrected short-axis cardiac sections obtained with SPECT/CT in a 32-year-old man by using three respiratory protocols and internal landmarks for registration. (a) Image acquired during postinhalation breath hold shows severe artifact that suggests decreased radiotracer uptake in the inferior wall (arrows). (b, c) Images acquired during postexhalation breath hold (b) and during free breathing (c) show no artifact.
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Figure 4c. Final attenuation-corrected short-axis cardiac sections obtained with SPECT/CT in a 32-year-old man by using three respiratory protocols and internal landmarks for registration. (a) Image acquired during postinhalation breath hold shows severe artifact that suggests decreased radiotracer uptake in the inferior wall (arrows). (b, c) Images acquired during postexhalation breath hold (b) and during free breathing (c) show no artifact.
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Figure 5a. Final attenuation-corrected short-axis cardiac sections obtained with SPECT/CT in a 60-year-old man during postinhalation breath hold. (a) Image obtained with registration based on external markers shows severe artifact (arrows) suggestive of decreased radiotracer uptake in the inferior wall. (b) Image obtained with registration based on internal landmarks shows no artifact.
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Figure 5b. Final attenuation-corrected short-axis cardiac sections obtained with SPECT/CT in a 60-year-old man during postinhalation breath hold. (a) Image obtained with registration based on external markers shows severe artifact (arrows) suggestive of decreased radiotracer uptake in the inferior wall. (b) Image obtained with registration based on internal landmarks shows no artifact.
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Figure A1. Transverse CT image of SPECT phantom. Cylinder A contains water and 201Tl; cylinders B, C, and D, diluted contrast material with different iodine concentrations and 201Tl.
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Figure A2. Attenuation-corrected SPECT/CT image, obtained by using low-current CT in the same phantom as in Figure A1, shows uniform attenuation in cylinders A–D.
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Copyright © 2005 by the Radiological Society of North America.
