title: Effects of a high-pitch protocol and a hybrid iterative reconstruction algorithm on image quality of cerebral subtracted 3D CT angiography.
abstract: OBJECTIVE
  To evaluate the image quality and the radiation dose of 3D-computed tomography angiography (3D-CTA) with a high-pitch protocol and a hybrid iterative reconstruction (HIR).
  
  
  METHODS
  This was a prospective study and thirty patients were scanned at a 0.51-helical pitch with filtered back-projection (FBP, protocol-A), and 30 patients were scanned at a 0.91-helical pitch with FBP and HIR (protocol-B and C). The mean volume CT dose index (CTDI(vol)), image noise, and mean cerebral arterial and venous attenuation were compared between the three protocols. Two readers assessed image noise, arterial contrast and venous overlap.
  
  
  RESULTS
  The mean CTDI(vol) of protocol-B/C (38.9 mGy) was lower than that of protocol-A (49.7 mGy). Mean image noise of protocol-B [12.6 ± 1.3 Hounsfield units (HU)] was higher than that of protocol-A (10.3 ± 1.2 HU). There was no significant difference in arterial attenuation between protocol-A (327.5 ± 57.5 HU) and C (327.7 ± 59.4 HU). Venous attenuation of protocol-C (148.5 ± 50.4 HU) was lower than that of protocol-A (185.9 ± 50.6 HU). In qualitative analysis, the image noise of protocol-B was higher than that of protocol-A/C. Venous enhancement of protocol-B/C was more inconspicuous than that of protocol-A.
  
  
  CONCLUSIONS
  3D-CTA with a high-pitch protocol and HIR can reduce radiation dose while decreasing venous enhancement and image noise to an adequate level for diagnosis.
authors.affiliation: Diagnostic Radiology, Amakusa Medical Center, kameba 854-1, Amakusa, Kumamoto, 863-0046, Japan. iyamayuuji28@gmail.com.|Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto, 860-8556, Japan. iyamayuuji28@gmail.com.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Iyama
authors.affiliation: Diagnostic Radiology, Amakusa Medical Center, kameba 854-1, Amakusa, Kumamoto, 863-0046, Japan. kff00712@nifty.com.|Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto, 860-8556, Japan. kff00712@nifty.com.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakaura
authors.affiliation: Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto, 860-8556, Japan. masafkidoh@yahoo.co.jp.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kidoh
authors.affiliation: Diagnostic Radiology, Amakusa Medical Center, kameba 854-1, Amakusa, Kumamoto, 863-0046, Japan. nkiyo0ctls@yahoo.co.jp.
authors.forename: Naoto
authors.initials: N
authors.lastname: Kiyota
authors.affiliation: Department of Neurosurgery, Amakusa Medical Center, kameba 854-1, Amakusa, Kumamoto, 863-0046, Japan. syouzaburouuemura@gmail.com.
authors.forename: Shouzaburou
authors.initials: S
authors.lastname: Uemura
authors.affiliation: Department of Surgery, Amakusa Medical Center, kameba 854-1, Amakusa, Kumamoto, 863-0046, Japan. k-harada@amed.jp.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Harada
authors.affiliation: Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto, 860-8556, Japan. yama@kumamoto-u.ac.jp.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002533:Cerebral Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: 3D-computed tomography angiography; Head and neck; Hybrid iterative reconstruction; Imaging