title: Resistance index measured by Doppler ultrasound as a predictor of graft function after kidney transplantation.
abstract: BACKGROUND
  Doppler ultrasound (US) has become the primary imaging technique for the evaluation of renal transplants. It provides information about the intrarenal resistance index (RI). A high RI is seen in every form of graft dysfunction. In this article, we review the utility of sonography, particularly the intrarenal RI measured early after renal transplant, as a predictor of acute and chronic clinical outcome in patients.
  
  
  RESULTS
  RI is a valuable marker to determine graft function and related vascular complications. It reveals a strong correlation with serum creatinine levels measured days after transplant. Its elevation is typical for acute tubular necrosis and can be used to predict its duration. An RI >1 (absent end-diastolic flow) seen in the first weeks after transplant is associated with impaired renal graft recovery. In addition, it is an early predictor of chronic allograft nephropathy (even correlated with biopsy results), which will allow a change in therapy.
  
  
  CONCLUSIONS
  RI measured serially in the early period after kidney transplantation is a valuable marker for determining renal graft function. It is also useful for demonstrating various types of graft dysfunction; however, it cannot differentiate between them. In recent studies, extrarenal factors in kidney transplantation (eg, recipient's age) may significantly influence RI in the recipient, demonstrating that RI depends on the vascular characteristics of the recipient and not on the graft itself.
authors.affiliation: Organ and Tissues Transplant Group, School of Medicine at the National University of Colombia, Bogotá, Columbia. Electronic address: hernancano123@gmail.com.
authors.forename: H
authors.initials: H
authors.lastname: Cano
authors.affiliation: Organ and Tissues Transplant Group, School of Medicine at the National University of Colombia, Bogotá, Columbia.
authors.forename: D A
authors.initials: DA
authors.lastname: Castañeda
authors.affiliation: Organ and Tissues Transplant Group, School of Medicine at the National University of Colombia, Bogotá, Columbia.
authors.forename: N
authors.initials: N
authors.lastname: Patiño
authors.affiliation: Organ and Tissues Transplant Group, School of Medicine at the National University of Colombia, Bogotá, Columbia.
authors.forename: H C
authors.initials: HC
authors.lastname: Pérez
authors.affiliation: Organ and Tissues Transplant Group, School of Medicine at the National University of Colombia, Bogotá, Columbia.
authors.forename: M
authors.initials: M
authors.lastname: Sánchez
authors.affiliation: Organ and Tissues Transplant Group Chief, Kidney Transplant Surgeron at San Ignacio Hospital, Bogotá, Colombia.
authors.forename: E
authors.initials: E
authors.lastname: Lozano
authors.affiliation: Radiologist, Fundación Cardio Infantil, Bogotá, Colombia.
authors.forename: M C
authors.initials: MC
authors.lastname: Pérez
mesh_terms: D051799:Delayed Graft Function / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006084:Graft Rejection / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006085:Graft Survival / Q000502:physiology; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016030:Kidney Transplantation; D007683:Kidney Tubular Necrosis, Acute / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000503:physiopathology; D018608:Ultrasonography, Doppler