title: Improved T2* imaging without increase in scan time: SWI processing of 2D gradient echo.
abstract: OBJECTIVE
  2D gradient-echo imaging is sensitive to T2* lesions (hemorrhages, mineralization, and vascular lesions), and susceptibility-weighted imaging is even more sensitive, but at the cost of additional scan time (SWI: 5-10 minutes; 2D gradient-echo: 2 minutes). The long acquisition time of SWI may pose challenges in motion-prone patients. We hypothesized that 2D SWI/phase unwrapped images processed from 2D gradient-echo imaging could improve T2* lesion detection.
  
  
  METHODS
  2D gradient-echo brain images of 50 consecutive pediatric patients (mean age, 8 years) acquired at 3T were retrospectively processed to generate 2D SWI/phase unwrapped images. The 2D gradient-echo and 2D SWI/phase unwrapped images were compared for various imaging parameters and were scored in a blinded fashion.
  
  
  RESULTS
  Of 50 patients, 2D gradient-echo imaging detected T2* lesions in 29 patients and had normal findings in 21 patients. 2D SWI was more sensitive than standard 2D gradient-echo imaging in detecting T2* lesions (P < .0001). 2D SWI/phase unwrapped imaging also improved delineation of normal venous structures and nonpathologic calcifications and helped distinguish calcifications from hemorrhage. A few pitfalls of 2D SWI/phase unwrapped imaging were noted, including worsened motion and dental artifacts and challenges in detecting T2* lesions adjacent to calvaria or robust deoxygenated veins.
  
  
  CONCLUSIONS
  2D SWI and associated phase unwrapped images processed from standard 2D gradient-echo images were more sensitive in detecting T2* lesions and delineating normal venous structures and nonpathologic mineralization, and they also helped distinguish calcification at no additional scan time. SWI processing of 2D gradient-echo images may be a useful adjunct in cases in which longer scan times of 3D SWI are difficult to implement.
authors.affiliation: Department of Radiology, Lucile Packard Children's Hospital, Stanford University, Palo Alto, California.
authors.forename: S
authors.initials: S
authors.lastname: Soman
authors.forename: S J
authors.initials: SJ
authors.lastname: Holdsworth
authors.forename: P D
authors.initials: PD
authors.lastname: Barnes
authors.forename: J
authors.initials: J
authors.lastname: Rosenberg
authors.forename: J B
authors.initials: JB
authors.lastname: Andre
authors.forename: R
authors.initials: R
authors.lastname: Bammer
authors.forename: K W
authors.initials: KW
authors.lastname: Yeom
mesh_terms: D000293:Adolescent; D000465:Algorithms; D001921:Brain / Q000473:pathology*; D001927:Brain Diseases / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007223:Infant; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult