title: Diffusion tensor imaging of the human kidney: Does image registration permit scanning without respiratory triggering?
abstract: To investigate if image registration of diffusion tensor imaging (DTI) allows omitting respiratory triggering for both transplanted and native kidneys
  
  
  
  Nine kidney transplant recipients and eight healthy volunteers underwent renal DTI on a 3T scanner with and without respiratory triggering. DTI images were registered using a multimodal nonrigid registration algorithm. Apparent diffusion coefficient (ADC), the contribution of perfusion (FP ), and the fractional anisotropy (FA) were determined. Relative root mean square errors (RMSE) of the fitting and the standard deviations of the derived parameters within the regions of interest (SDROI ) were evaluated as quality criteria.
  
  
  
  Registration significantly reduced RMSE in all DTI-derived parameters of triggered and nontriggered measurements in cortex and medulla of both transplanted and native kidneys (P < 0.05 for all). In addition, SDROI values were lower with registration for all 16 parameters in transplanted kidneys (14 of 16 SDROI values were significantly reduced, P < 0.04) and for 15 of 16 parameters in native kidneys (9 of 16 SDROI values were significantly reduced, P < 0.05). Comparing triggered versus nontriggered DTI in transplanted kidneys revealed no significant difference for RMSE (P > 0.14) and for SDROI (P > 0.13) of all parameters. In contrast, in native kidneys relative RMSE from triggered scans were significantly lower than those from nontriggered scans (P < 0.02), while SDROI was slightly higher in triggered compared to nontriggered measurements in 15 out of 16 comparisons (significantly for two, P < 0.05).
  
  
  
  Registration improves the quality of DTI in native and transplanted kidneys. Diffusion parameters in renal allografts can be measured without respiratory triggering. In native kidneys, respiratory triggering appears advantageous. J. Magn. Reson. Imaging 2016;44:327-334.
authors: Department of Clinical Research and Radiology, University of Bern, Bern, Switzerland.
authors: Maryam
authors: M
authors: Seif
authors: Department of Nephrology, Hypertension and Clinical Pharmacology, University Hospital of Bern, Switzerland.
authors: Laila Yasmin
authors: LY
authors: Mani
authors: Institute for Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland.
authors: Huanxiang
authors: H
authors: Lu
authors: Department of Clinical Research and Radiology, University of Bern, Bern, Switzerland.
authors: Chris
authors: C
authors: Boesch
authors: Institute for Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland.
authors: Mauricio
authors: M
authors: Reyes
authors: Department of Nephrology, Hypertension and Clinical Pharmacology, University Hospital of Bern, Switzerland.
authors: Bruno
authors: B
authors: Vogt
authors: Department of Clinical Research and Radiology, University of Bern, Bern, Switzerland.
authors: Peter
authors: P
authors: Vermathen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000465:Algorithms; D016477:Artifacts; D056324:Diffusion Tensor Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods*; D007668:Kidney / Q000000981:diagnostic imaging* / Q000601:surgery; D016030:Kidney Transplantation; D008875:Middle Aged; D015203:Reproducibility of Results; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013382:Subtraction Technique; D055815:Young Adult
keywords: DTI; diffusion; kidney; motion correction; nonrigid image registration; respiratory triggering