title: Volume-rendered multidetector CT angiography: noninvasive follow-up of patients treated with renal artery stents.
abstract: OBJECTIVE
  The purpose of our study was to evaluate the role of multidetector CT (MDCT) angiography with volume rendering for estimating the patency of renal artery stents.
  
  
  METHODS
  In 16 patients, 16 renal artery stents were evaluated with MDCT renal angiography and digital subtraction angiography (DSA). CT data were evaluated using multiplanar volume reformations and the volume-rendering algorithm with three different volume-rendered parameter settings (low-to-high, high-to-low, and high-low-high opacity transfer functions: VR(LH), VR(HL), and VR(VE), respectively). Targeted images of each stent were rendered in paraaxial and paracoronal planes and were interactively interpreted. The overall restenosis severity was measured on postprocessed paraaxial and paracoronal images and compared with that obtained on DSA using linear regression analysis. Image quality and lumen delineation on rendered images were also compared using Wilcoxon's signed rank test.
  
  
  RESULTS
  Eight restenoses were identified on DSA. Correlations between restenosis severity measured with DSA and those measured with MDCT were significant (p < 0.001). Volume rendering with VR(HL) allowed the best correlation with DSA (reviewer 1, r(2) = 0.86; reviewer 2, r(2) = 0.94) and was significantly better than multiplanar volume reformations (p = 0.028). Overall image quality was high with all rendering techniques and with no significant differences (p > 0.59, for all comparisons). Stent lumen was well delineated with volume-rendering modalities; however, VR(HL) was significantly better than VR(LH) (p = 0.033).
  
  
  CONCLUSIONS
  Volume-rendered MDCT angiography enabled high-quality three-dimensional reproducible evaluation of the patency of implanted renal artery stents. Volume rendering with VR(HL) achieved the best performance.
authors.affiliation: Department of Radiology, Innsbruck University Hospital, Anichstrasse 35, 6020 Innsbruck, Austria.
authors.forename: Ammar
authors.initials: A
authors.lastname: Mallouhi
authors.forename: Michael
authors.initials: M
authors.lastname: Rieger
authors.forename: Benedikt
authors.initials: B
authors.lastname: Czermak
authors.forename: Martin C
authors.initials: MC
authors.lastname: Freund
authors.forename: Peter
authors.initials: P
authors.lastname: Waldenberger
authors.forename: Werner R
authors.initials: WR
authors.lastname: Jaschke
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015901:Angiography, Digital Subtraction; D017546:Angioscopy; D003287:Contrast Media; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012008:Recurrence; D012077:Renal Artery / Q000000981:diagnostic imaging* / Q000473:pathology; D012078:Renal Artery Obstruction / Q000000981:diagnostic imaging* / Q000473:pathology / Q000628:therapy; D015607:Stents; D014057:Tomography, X-Ray Computed / Q000379:methods; D014654:Vascular Patency
chemical_list: D003287:Contrast Media