title: Simultaneous imaging of radiation-induced cerebral microbleeds, arteries and veins, using a multiple gradient echo sequence at 7 Tesla.
abstract: BACKGROUND
  The purpose of this study was to implement and evaluate the utility of a multi-echo sequence at 7 Tesla (T) for simultaneous time-of-flight (TOF) MR-angiography (MRA) and susceptibility-weighted imaging (SWI) of radiation-induced cerebral microbleeds (CMBs), intracranial arteries, and veins.
  
  
  METHODS
  A four-echo gradient-echo sequence was implemented on a 7T scanner. The first echo was used to create TOF-MRA images, while the remaining echoes were combined to visualize CMBs and veins on SWI images. The sequence was evaluated on eight brain tumor patients with known radiation-induced CMBs. Single-echo images were also acquired to visually and quantitatively compare the contrast-to-noise ratio (CNR) of small- and intermediate-vessels between acquisitions. The number of CMBs detected with each acquisition was also quantified. Statistical significance was determined using a Wilcoxon signed-rank test.
  
  
  RESULTS
  Compared with the single-echo sequences, the CNR of small and intermediate arteries increased 7.6% (P < 0.03) and 9.5% (P = 0.06), respectively, while the CNR of small and intermediate veins were not statistically different between sequences (P = 0.95 and P = 0.46, respectively). However, these differences were not discernible by visual inspection. Also the multi-echo sequence detected 18.3% more CMBs (P < 0.008) due to higher slice resolution.
  
  
  CONCLUSIONS
  The proposed 7T multi-echo sequence depicts arteries, veins, and CMBs on a single image to facilitate quantitative evaluation of radiation-induced vascular injury.
authors.affiliation: The UC Berkeley-UCSF Graduate Program in Bioengineering, University of California San Francisco, San Francisco, California, USA.|Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Bian
authors.affiliation: Global Applied Science Laboratory, GE Healthcare, Menlo Park, California, USA.
authors.forename: Suchandrima
authors.initials: S
authors.lastname: Banerjee
authors.affiliation: Global Applied Science Laboratory, GE Healthcare, San Francisco, California, USA.
authors.forename: Douglas A C
authors.initials: DA
authors.lastname: Kelly
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Hess
authors.affiliation: The UC Berkeley-UCSF Graduate Program in Bioengineering, University of California San Francisco, San Francisco, California, USA.|Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.
authors.forename: Peder E Z
authors.identifier: http://orcid.org/0000-0003-4183-3634
authors.initials: PE
authors.lastname: Larson
authors.affiliation: Department of Neurological Surgery, University of California San Francisco, San Francisco, California, USA.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Chang
authors.affiliation: The UC Berkeley-UCSF Graduate Program in Bioengineering, University of California San Francisco, San Francisco, California, USA.|Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.|Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, USA.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Nelson
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.
authors.forename: Janine M
authors.initials: JM
authors.lastname: Lupo
mesh_terms: D000328:Adult; D001930:Brain Injuries / Q000209:etiology / Q000473:pathology; D002536:Cerebral Arteries / Q000473:pathology*; D002543:Cerebral Hemorrhage / Q000209:etiology / Q000473:pathology*; D002550:Cerebral Veins / Q000473:pathology*; D017352:Echo-Planar Imaging / Q000379:methods; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011832:Radiation Injuries / Q000209:etiology / Q000473:pathology*; D020266:Radiotherapy, Conformal / Q000009:adverse effects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: 7T; SWI; TOF-MRA; microbleeds; multi-echo; radiation effects