title: Corticomedullary differentiation of the kidney: evaluation with noncontrast-enhanced steady-state free precession (SSFP) MRI with time-spatial labeling inversion pulse (time-SLIP).
abstract: OBJECTIVE
  To assess whether noncontrast-enhanced steady-state free precession (SSFP) magnetic resonance imaging (MRI) with time-spatial labeling inversion pulse (Time-SLIP) can improve the visibility of corticomedullary differentiation of the normal kidney.
  
  
  METHODS
  A series of noncontrast-enhanced SSFP MRI with Time-SLIP were performed in 20 patients by using various inversion times (TIs); 500-1800 msec in increments of 100 msec. In-phase (IP) and opposed-phase (OP) MR images were also obtained. The signal intensity (SI) of the renal cortex and medulla was measured to calculate corticomedullary contrast ratio (SI of cortex/medulla). Additionally, the visibility of corticomedullary differentiation was visually categorized using a four-point scale.
  
  
  RESULTS
  In SSFP with Time-SLIP, corticomedullary contrast ratio was highest with TI of 1200 msec in eight subjects (40%), followed by 1100 msec in seven (35%) and 1000 msec in three (15%). The corticomedullary contrast ratio in SSFP with optimal Time-SLIP (4.93 ± 1.25) was significantly higher (P < 0.001) than those of IP (1.46 ± 0.12) and OP (1.43 ± 0.14). The visibility of corticomedullary differentiation was significantly better (P < 0.001) in SSFP images with Time-SLIP (averaged grade = 4.0) than in IP images (averaged grade = 2.63) and OP images (averaged grade = 2.05).
  
  
  CONCLUSIONS
  SSFP MRI with Time-SLIP can improve the visibility of renal corticomedullary differentiation without using contrast agents.
authors.affiliation: Department of Radiology, Kawasaki Medical School, Kurashiki, Japan. ponbon@med.kawasaki-m.ac.jp
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kanki
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Ito
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Tamada
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Noda
authors.forename: Akira
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Daigo
authors.initials: D
authors.lastname: Tanimoto
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Sato
authors.forename: Atsushi
authors.initials: A
authors.lastname: Higaki
mesh_terms: D000328:Adult; D000465:Algorithms; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007672:Kidney Cortex / Q000033:anatomy & histology*; D007679:Kidney Medulla / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels; D055815:Young Adult
chemical_list: D003287:Contrast Media; D013113:Spin Labels