title: Diffusion weighted imaging and diffusion tensor imaging in the evaluation of transplanted kidneys.
abstract: OBJECTIVE
  The aim of this study is to investigate the relation between renal indexes and functional MRI in a population of kidney transplant recipients who underwent MR with diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) of the transplanted graft.
  
  
  METHODS
  Study population included 40 patients with single kidney transplant. The patients were divided into 3 groups, on the basis of creatinine clearance (CrCl) values calculated using Cockcroft-Gault formula: group A, including patients with normal renal function (CrCl ≥ 60 mL/min); group B, which refers to patients with moderate renal impairment (CrCl > 30 but <60 mL/min); and, finally, group C, which means severe renal deterioration (CrCl ≤ 30 mL/min). All patients were investigated with a 1.5 Tesla MRI scanner, acquiring DWI and DTI sequences. A Mann-Whitney U test was adopted to compare apparent diffusion coefficients (ADCs) and fractional anisotropy (FA) measurements between groups. Receiver operating characteristic (ROC) curves were created for prediction of normal renal function (group A) and renal failure (group C). Pearson correlation was performed between renal clearance and functional imaging parameter (ADC and FA), obtained for cortical and medullar regions.
  
  
  RESULTS
  Mann-Whitney U test revealed a highly significant difference (p < 0.01) between patients with low CrCl (group C) and normal CrCl (group A) considering both medullar ADC and FA and cortical ADC. Regarding contiguous groups, the difference between group B and C was highly significant (p < 0.01) for medullar ADC and significant (p < 0.05) for cortical ADC and medullar FA. No difference between these groups was found considering cortical FA. Analyzing groups A and B, we found a significant difference (p < 0.05) for medullar both ADC and FA, while no difference was found for cortical ADC and FA. Strongest Pearson correlation was found between CrCl and medullar ADC (r = 0.65). For predicting normal renal function or severe renal impairment, highest values of AUC were observed using medullar ADC cut-off values (respectively 0.885 and 0.871); medullar FA showed also high accuracy (respectively 0.831 and 0.853).
  
  
  CONCLUSIONS
  DWI and DTI are promising tools for non-invasive monitoring of renal function; medullar ADC proved to be the best parameter for renal function assessment.
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Via Santa Sofia 78, 95123 Catania, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Palmucci
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Via Santa Sofia 78, 95123 Catania, Italy.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Cappello
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Via Santa Sofia 78, 95123 Catania, Italy.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Attinà
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Via Santa Sofia 78, 95123 Catania, Italy.
authors.forename: Pietro Valerio
authors.initials: PV
authors.lastname: Foti
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Via Santa Sofia 78, 95123 Catania, Italy.
authors.forename: Rita Olivia Anna
authors.initials: RO
authors.lastname: Siverino
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Via Santa Sofia 78, 95123 Catania, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Roccasalva
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Via Santa Sofia 78, 95123 Catania, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Piccoli
authors.affiliation: Vascular Surgery and Organ Transplant Unit, Department of Surgery, Transplantation and Advanced Technologies, University Hospital "Policlinico-Vittorio Emanuele", Via Santa Sofia 78, 95123 Catania, Italy.
authors.forename: Nunziata
authors.initials: N
authors.lastname: Sinagra
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Via Santa Sofia 78, 95123 Catania, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Milone
authors.affiliation: Vascular Surgery and Organ Transplant Unit, Department of Surgery, Transplantation and Advanced Technologies, University Hospital "Policlinico-Vittorio Emanuele", Via Santa Sofia 78, 95123 Catania, Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Veroux
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Via Santa Sofia 78, 95123 Catania, Italy.
authors.forename: Giovanni Carlo
authors.initials: GC
authors.lastname: Ettorre
keywords: ADC, apparent diffusion coefficient; AUC, area under the curve; CrCl, creatinine clearance; DTI, diffusion tensor imaging; DWI, diffusion weighted imaging; Diffusion tensor imaging; Diffusion weighted MRI; FA, fractional anisotropy; Kidney transplantation; Magnetic resonance imaging; ROC, receiver operating characteristic curve; ROI, region of interest