title: Diffusion-weighted MR imaging of kidneys in renal artery stenosis.
abstract: OBJECTIVE
  The purpose of our study was to evaluate perfusion and diffusion of kidneys in renal artery stenosis (RAS) and any correlation between stenosis and ADC values and whether this imaging modality may be a noninvasive complementary assessment technique to MR angiography before interventional procedures.
  
  
  METHODS
  Twenty consecutive patients suspected of having renal artery stenosis were evaluated with renal MR angiography to exclude stenosis and were then included in the study. Transverse DW multisection echo-planar MR imaging was performed. In the transverse ADC map, rectangular regions of interest were placed in the cortex on 3 parts (upper, middle, and lower poles) in each kidney. ADCs of the kidneys were calculated separately for the low, average, and high b-values to enable differentiation of the relative influence of the perfusion fraction and true diffusion. The ADC values of 39 kidneys (13 with renal artery stenosis and 26 normal renal arteries) were compared, and the relationship between stenosis degree and ADC values was calculated.
  
  
  RESULTS
  RAS was detected in 11 of 20 (55%) patients with MRA. Thirteen of 39 kidneys demonstrated RAS, and 26 were normal. The ADClow (1.9+/-0.2 versus 2.1+/-0.2; P=.020), ADCaverage (1.7+/-0.2 versus 1.9+/-0.1; P=.006), and ADChigh (1.8+/-0.2 versus 2.0+/-0.1; P=.012) values were significantly lower in patients with kidneys with arterial stenosis than that in patients with kidneys with normal arteries. Statistical analysis revealed that stenosis degree correlated strongly with ADClow (r=-.819; P=.001), ADCaverage (r=-.754; P=.003), and ADChigh (r=-.788; P=.001). The ADClow, ADCaverage, and ADChigh values were significantly lower in patients with kidneys with arterial stenosis than that in patients with kidneys with normal arteries.
  
  
  CONCLUSIONS
  We think that DW MR imaging of kidneys with RAS can help determine the functional status of a renal artery stenosis.
authors.affiliation: Baskent University Medical School, Department of Radiology, Ankara, Turkey. drerkany@yahoo.com
authors.forename: Erkan
authors.initials: E
authors.lastname: Yildirim
authors.forename: Ismail
authors.initials: I
authors.lastname: Kirbas
authors.forename: Mehmet
authors.initials: M
authors.lastname: Teksam
authors.forename: Elif
authors.initials: E
authors.lastname: Karadeli
authors.forename: Hakan
authors.initials: H
authors.lastname: Gullu
authors.forename: Ismail
authors.initials: I
authors.lastname: Ozer
mesh_terms: D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D012078:Renal Artery Obstruction / Q000175:diagnosis*; D012079:Renal Circulation