title: Assessment of renal allograft fibrosis by acoustic radiation force impulse quantification--a pilot study.
abstract: Chronic allograft nephropathy characterized by interstitial fibrosis and tubular atrophy is a major cause of renal transplant failure. Acoustic radiation force impulse (ARFI) quantification is a promising noninvasive method for assessing tissue stiffness. We evaluated if the method could reveal renal transplant fibrosis. In a prospective study, 30 adult renal transplant recipients were included. ARFI quantification, given as shear wave velocity (SWV), of the renal cortex was performed by two observers. SWV was compared to grade of fibrosis (0-3) in biopsies. The median SWV was 2.8 m/s (range: 1.6-3.6), 2.6 m/s (range: 1.8-3.5) and 2.5 m/s (range: 1.6-3) for grade 0 (n = 12), 1 (n = 10) and grades 2/3 (n = 8) fibrosis respectively. SWV did not differ significantly in transplants without and with fibrosis (grade 0 vs. grade 1, P = 0.53 and grade 0 vs. grades 2/3, P = 0.11). The mean intraobserver coefficient of variation was 22% for observer 1 and 24% for observer 2. Interobserver agreement, expressed as intraclass correlation coefficient was 0.31 (95% CI: -0.03 to 0.60). This study does not support the use of ARFI quantification to assess low-grade fibrosis in renal transplants. ARFI quantification in its present stage of development has also high intra- and interobserver variation in renal transplants.
authors.affiliation: Department of Radiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway. trygve.syversveen@rikshospitalet.no
authors.forename: Trygve
authors.initials: T
authors.lastname: Syversveen
authors.forename: Knut
authors.initials: K
authors.lastname: Brabrand
authors.forename: Karsten
authors.initials: K
authors.lastname: Midtvedt
authors.forename: Erik H
authors.initials: EH
authors.lastname: Strøm
authors.forename: Anders
authors.initials: A
authors.lastname: Hartmann
authors.forename: Jarl A
authors.initials: JA
authors.lastname: Jakobsen
authors.forename: Audun E
authors.initials: AE
authors.lastname: Berstad
mesh_terms: D000328:Adult; D000368:Aged; D054459:Elasticity Imaging Techniques; D005260:Female; D005355:Fibrosis; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging / Q000473:pathology*; D007674:Kidney Diseases / Q000000981:diagnostic imaging / Q000473:pathology; D016030:Kidney Transplantation / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects