title: Reduced-dose CT protocol for the assessment of cerebral vasospasm.
abstract: BACKGROUND
  Despite the increased radiation dose, multimodal CT including noncontrast CT (NCT), CT angiography (CTA), and perfusion CT (PCT) remains a useful tool for the diagnosis of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). The aim of this study was to assess the radiation dose and the image quality between a standard-dose and a reduced-dose multimodal CT protocol.
  
  
  METHODS
  The study group consisted of 26 aSAH patients with a suspicion of DCI on clinical examination and transcranial doppler. Two different CT protocols were used: a standard-dose protocol (NCT 120 kV, 350 mAs; CTA 100 kV, 250 mAs; PCT 80 kV, 200 mAs) from August 2011 to October 2013 (n = 13) and a reduced-dose protocol (NCT 100 kV, 400 mAs; CTA 100 kV, 220 mAs; PCT 80 kV, 180 mAs) from November 2013 to May 2014 (n = 13). Dose-length product (DLP), effective dose, volume CT dose index (CTDI), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and overall image quality were determined for each examination.
  
  
  RESULTS
  The overall image quality was judged as good or excellent in all cases. The reduced-dose protocol allowed a 15 % decrease in both the median total DLP (2438 vs 2898 mGy cm, p < 0.0001) and the effective dose as well as a significant decrease in median CTDI of 23, 31, and 10 % for NCT, CTA, and CTP, respectively. This dose reduction did not result in significant alteration of SNR (except for NCT) or CNR between groups.
  
  
  CONCLUSIONS
  The present study showed that the reduced-dose multimodal CT protocol enabled a significant reduction of radiation dose without image quality impairment.
authors: Department of Neuroradiology, Université Lille Nord de France, Hôpital Roger Salengro, CHRU de Lille, Avenue Emile-Laine, 59037, Lille cedex, France. bricout.nicolas@gmail.com.
authors: N
authors: N
authors: Bricout
authors: Department of Neuroradiology, Université Lille Nord de France, Hôpital Roger Salengro, CHRU de Lille, Avenue Emile-Laine, 59037, Lille cedex, France.
authors: L
authors: L
authors: Estrade
authors: Department of Neuroradiology, Université Lille Nord de France, Hôpital Roger Salengro, CHRU de Lille, Avenue Emile-Laine, 59037, Lille cedex, France.
authors: F
authors: F
authors: Boustia
authors: Department of Neuroradiology, Université Lille Nord de France, Hôpital Roger Salengro, CHRU de Lille, Avenue Emile-Laine, 59037, Lille cedex, France.
authors: E
authors: E
authors: Kalsoum
authors: Department of Neuroradiology, Université Lille Nord de France, Hôpital Roger Salengro, CHRU de Lille, Avenue Emile-Laine, 59037, Lille cedex, France.
authors: J P
authors: JP
authors: Pruvo
authors: Department of Neuroradiology, Université Lille Nord de France, Hôpital Roger Salengro, CHRU de Lille, Avenue Emile-Laine, 59037, Lille cedex, France.
authors: X
authors: X
authors: Leclerc
mesh_terms: D000328:Adult; D000368:Aged; D002533:Cerebral Angiography / Q000379:methods / Q000592:standards*; D005260:Female; D005602:France; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods / Q000592:standards*; D017410:Practice Guidelines as Topic; D011829:Radiation Dosage; D000069079:Radiation Exposure / Q000032:analysis*; D011835:Radiation Protection / Q000379:methods / Q000592:standards*; D011874:Radiometry / Q000592:standards; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000592:standards*; D020301:Vasospasm, Intracranial / Q000150:complications / Q000000981:diagnostic imaging*
keywords: Cerebral perfusion; Computed tomography; Radiation dose; Vasospasm