title: Optimizing functional MR urography: prime time for a 30-minutes-or-less fMRU.
abstract: BACKGROUND
  Current protocols for functional MR urography (fMRU) require long scan times, limiting its widespread use.
  
  
  OBJECTIVE
  Our goal was to use pre-defined criteria to reduce the number of sequences and thus the examination time without compromising the morphological and functional results.
  
  
  METHODS
  The standard fMRU protocol in our department consists of eight sequences, including a 17-min dynamic post-contrast scan. Ninety-nine children and young adults (43 male, 56 female, mean age 7 years) were evaluated with this protocol. Each sequence was retrospectively analyzed for its utility and factors that affect its duration.
  
  
  RESULTS
  Mean scan time to perform the eight sequences, without including the variable time between sequences, was 40.5 min. Five sequences were categorized as essential: (1) sagittal T2 for planning the oblique coronal plane, (2) axial T2 with fat saturation for the assessment of corticomedullary differentiation and parenchymal thickness, (3) coronal 3-D T2 with fat saturation for multiplanar and 3-D reconstructions, (4) pre-contrast coronal T1 with fat saturation to ensure an appropriate scan prior to injecting the contrast material and (5) the coronal post-contrast dynamic series. Functional information was obtained after 8 min of dynamic imaging in the majority of children. The coronal fat-saturated T2, coronal T1, and post-contrast sagittal fat-saturated T1 sequences did not provide additional information. Because of the effects of pelvicalyceal dilation and ureteropelvic angle on the renal transit time, prone position is recommended, at least in children with high-grade pelvicalyceal dilation.
  
  
  CONCLUSIONS
  Comprehensive fMRU requires approximately 19 min for sequence acquisition. Allowing for time between sequences and motion correction, the total study time can be reduced to about 30 min. Four pre-contrast sequences and a shortened post-contrast dynamic scan, optimally with the child in prone position, are sufficient.
authors: Department of Radiology, The Children's Hospital of Philadelphia, 34th Street and Civic Center Boulevard, Philadelphia, PA, 19104, USA, jorge.delgado.londono@gmail.com.
authors: Jorge
authors: J
authors: Delgado
authors: Maria A
authors: MA
authors: Bedoya
authors: Melkamu
authors: M
authors: Adeb
authors: Robert H
authors: RH
authors: Carson
authors: Ann M
authors: AM
authors: Johnson
authors: Dmitry
authors: D
authors: Khrichenko
authors: Douglas A
authors: DA
authors: Canning
authors: Kassa
authors: K
authors: Darge
mesh_terms: D000465:Algorithms; D002648:Child; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors; D014567:Urography / Q000379:methods*; D014570:Urologic Diseases / Q000175:diagnosis*