KEIGO NARITA

Last Updated :2022/12/01

Affiliations, Positions
Hiroshima University Hospital(Medical), Assistant Professor
E-mail
yuttfagchiroshima-u.ac.jp

Basic Information

Educational Backgrounds

  • Hiroshima University, Graduate School of Biomedical & Health Sciences , Japan, 2017/10, 2021/03

Affiliated Academic Societies

  • Japan Radiological Society

Educational Activity

Course in Charge

  1. 2022, Undergraduate Education, Intensive, Practice of Medicine I

Research Activities

Academic Papers

  1. Deep learning reconstruction of drip-infusion cholangiography acquired with ultra-high-resolution computed tomography, Abdominal Radiology, 45(9), 2698-2704, 202009
  2. Deep learning reconstruction improves image quality of abdominal ultra-high-resolution CT, EUROPEAN RADIOLOGY, 6163-6171, 20190411
  3. Diagnostic value of deep learning reconstruction for radiation dose reduction at abdominal ultra-high-resolution CT, EUROPEAN RADIOLOGY, 31(7), 4700-4709, 202107
  4. Advanced CT techniques for assessing hepatocellular carcinoma, RADIOLOGIA MEDICA, 126(7), 925-935, 202107

Invited Lecture, Oral Presentation, Poster Presentation

  1. Radiation dose reduction at abdominal ultra-high-resolution CT with deep learning reconstruction, Narita K, Nakamura Y, Higaki T, Akagi M, Honda Y, Awai K, RSNA2020, 2020/12/02, Without Invitation, English, Radiological Society of North America, Chicago, Illionis, USA (Web), Ultra-high-resolution computed tomography, U-HRCT, involves a smaller detector element and tube focus size than conventional CT. It yields images of higher spatial resolution. However, due to its smaller detectors, higher radiation doses are required especially for abdominal U-HRCT because the noise is higher than on conventional CT scans. On the other hand, deep learning reconstruction, DLR, the first commercialized deep-learning reconstruction tool, introduces deep convolutional neural networks that are trained on a teaching dataset of ideal model-based iterative reconstruction, MBIR, images into the reconstruction flow. The image quality of abdominal CT scans has been reported to be better on U-HRCT images subjected to DLR than MBIR and hybrid-IR. The purpose of this study was to identify the method that allowed for the greatest radiation dose reduction while preserving the diagnostic value. Total 72 patients who underwent hepatic dynamic CT acquired with U-HRCT were included in this study. Of these 36 patients were scanned with standard radiation dose (SD group) and other 36 patients were scanned with lower radiation dose (LD group). Lower dose was defined as 70% of the standard dose. The patients’ age, sex, and body mass index (BMI) were matched between two groups. Hepatic dynamic CT images during hepatic arterial phase (HAP) and equilibrium phase (EP) were scanned in super-high-resolution mode. The SD HAP- and EP images were reconstructed with hybrid-IR; the LD HAP- and EP images with hybrid-IR, MBIR, and DLR. The SD hybrid-IR images were used as the reference standard. For image analysis, the standard deviation of the attenuation measured in the paraspinal muscle was used as image noise. And two board-certified radiologists ranked the HAP and EP images for overall image quality according to a five point scale. For statistical analysis, equivalence and potential superiority of LD images compared with the reference standard images, SD hybrid-IR images, were assessed. The image noise was lower and the subjective overall image quality score were higher on LD DLR- than the reference SD hybrid IR images. All criteria for superiority were fulfilled on LD-DLR images in both the HAP and EP. Therefore, DLR appears as an essential reconstruction method for abdominal U-HRCT because DLR can maintain the image quality even with radiation dose reduction. The image noise was higher on LD hybrid-IR- and lower on LD MBIR images than the reference SD hybrid IR images. The quality score for both LD hybrid-IR- and LD MBIR images was neither superior nor equivalent to the reference images. Taken together, we suppose that neither hybrid-IR nor MBIR may allow for a radiation dose reduction at abdominal U-HRCT without compromising the image quality. In conclusion, the radiation dose for abdominal U-HRCT can be reduced by 30% without degradation of image quality when DLR is applied to the acquired images.
  2. Utility of iterative noise reduction for gadoxetic acid-enhanced hepatobiliary-phase magnetic resonance imaging., Narita K, Nakamura Y, Higaki T, Nishihara T, Bito Y, Awai K, RSNA2020, 2020/11, Without Invitation, English