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Iterative Reconstruction Designed for Brain CT: A Correlative Study With Filtered Back Projection for the Diagnosis of Acute Ischemic Stroke

Iyama, Yuji MD*†; Nakaura, Takeshi MD*†; Oda, Seitaro MD; Kidoh, Masafumi MD; Utsunomiya, Daisuke MD; Yoshida, Morikatsu MD*†; Yuki, Hideaki MD; Hirata, Kenichiro MD; Funama, Yoshinori PhD; Harada, Kazunori MD§; Awai, Kazuo MD; Hirai, Toshinori MD; Yamashita, Yasuyuki MD

Journal of Computer Assisted Tomography: November/December 2017 - Volume 41 - Issue 6 - p 884–890
doi: 10.1097/RCT.0000000000000626
Neuroradiology

Objectives The objective of this study is to evaluate the usefulness of iterative model reconstruction designed for brain computed tomography (CT) (IMR-Neuro) for the diagnosis of acute ischemic stroke.

Methods This retrospective study included 20 patients with acute middle cerebral artery infarction who have undergone brain CT and 20 nonstroke patients (control). We reconstructed axial images with filtered back projection (FBP) and IMR-Neuro (slice thickness, 1 and 5 mm). We compared the CT number of the infarcted area, the image noise, contrast, and the contrast to noise ratio of the infarcted and the noninfarcted areas between the different reconstruction methods. We compared the performance of 10 radiologists in the detection of parenchymal hypoattenuation between 2 techniques using the receiver operating characteristic (ROC) techniques with the jackknife method.

Results The image noise was significantly lower with IMR-Neuro [5 mm: 2.5 Hounsfield units (HU) ± 0.5, 1 mm: 3.9 HU ± 0.5] than with FBP (5 mm: 4.9 HU ± 0.5, 1 mm: 10.1 HU ± 1.4) (P < 0.01). The contrast to noise ratio was significantly greater with IMR-Neuro (5 mm: 2.6 ± 2.1, 1 mm: 1.6 ± 1.3) than with FBP (5 mm: 1.2 ± 1.0; 1 mm: 0.6 ± 0.5) (P < 0.01). The value of the average area under the receiver operating curve was significantly higher with IMR-Neuro than FBP (5 mm: 0.79 vs 0.74, P = 0.04; 1 mm: 0.76 vs 0.69, P = 0.04).

Conclusions Compared with FBP, IMR-Neuro improves the image quality and the performance for the detection of parenchymal hypoattenuation with acute ischemic stroke.

From the *Diagnostic Radiology, Amakusa Medical Center, Kameba 854-1, Amakusa, Kumamoto 863-0046, Japan; †Department of Diagnostic Radiology, Graduate School of Medical Sciences, and ‡Faculty of Life Sciences, Department of Medical Physics, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto 860-8556, Japan; §Department of Surgery, Amakusa Medical Center, Kameba 854-1, Amakusa, Kumamoto 863-0046, Japan; ∥Department of Diagnostic Radiology, Graduate School of Medical Sciences, Institute of Biomedical and Health Sciences, Hiroshima University, Kasumi 1-2-3, Minamiku, Hiroshima, Hiroshima 860-8556, Japan; and ¶Department of Diagnostic Radiology, Graduate School of Medical Sciences, Miyazaki University, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan.

Received for publication December 9, 2016; accepted February 21, 2017.

Correspondence to: Takeshi Nakaura, MD, Diagnostic Radiology, Amakusa Medical Center, Kameba 854-1, Amakusa, Kumamoto 863-0046, Japan (e-mail: kff00712@nifty.com).

The authors declare no conflict of interest.

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