T2’ Imaging of Native Kidneys and Renal Allografts – a Feasibility Study

Zusammenfassung

Ziel: Evaluation der Durchführbarkeit der T 2’-Bildgebung von nativen und transplantierten Nieren. Material und Methoden: Nach positivem Votum der lokalen Ethikkommission wurden 24 nierentransplantierte Patienten und 10 gesunde Freiwillige als Kontrollen in die Studie eingeschlossen. An einem 1,5 Tesla MR-Tomografen wurden T 2- und T 2*-Multiecho-Sequenzen angefertigt. Die Patienten wurden 2 Gruppen zugeordnet: Gruppe a), 8 Patienten mit guter (glomeruläre Filtrationsrate [GFR] über 40 ml/min) Transplantatfunktion und fehlenden Zeichen einer Abstoßungsreaktion oder einer Harnleiter-Obstruktion; Guppe b), 16 Patienten mit reduzierter Transplantatfunktion (glomeruläre Filtrationsrate (GFR) von 40 ml/min oder weniger). 2 verschiedene Bildgebungsprotokolle wurden getestet. Ergebnisse: Die mittleren T 2’-Relaxationszeiten der Gruppen a), b) und der gesunden Probanden waren jeweils 108,33 ms ± 13,34, 100,00 ms ± 1889 and 124,57 ms ± 651. Die Verringerung der T 2’-Werte in Gruppe b) war nicht statistisch signifikant. Es zeigten sich jedoch signifikante Korrelationen zwischen den T 2’-Werten und der glomerulären Filtrationsrate (GFR). Die Analyse der Reproduzierbarkeit ergab Variationskoeffizienten von 11,1 % (intraindividuell) und 11,3 % (interindividuell). Schlussfolgerung: Die Studienergebnisse weisen darauf hin, dass es sich bei der T 2’-Bildgebung um eine vielversprechende, kontrastmittelfreie Technik handelt, welche scheinbar Informationen über die Transplantatfunktion vorhält. Weitere Studien sind erforderlich, um die klinische Wertigkeit des Verfahrens für das Monitoring nierentransplantierter Patienten zu erforschen.

Abstract

Purpose: To evaluate the feasibility of T 2’ mapping in native kidneys and renal allografts. Materials and Methods: Following approval of the local ethics committee, 24 renal allograft recipients and 10 control subjects (healthy volunteers) were included in this study. Multi-echo T 2 and T 2* imaging was performed on a 1.5 Tesla scanner. Allograft recipients were assigned to two groups: group a), 8 patients with good (glomerular filtration rate of more than 40 ml/min) allograft function and no evidence of transplant rejection, transplant renal artery stenosis or ureteral obstruction; group b), 16 patients with deterioration of renal graft function (glomerular filtration rate (GFR) of 40 ml/min or less). Two different imaging protocols were tested. Results: The mean T 2’ relaxation parameters were 108.33 msec ± 13.34, 100.00 msec ± 18.89 and 124.57 msec ± 6.51 for groups a), b) and for control subjects, respectively. The reduction of T 2’ values in patient group b) was not statistically significant. However, significant correlations could be demonstrated between T 2’ values and the glomerular filtration rate (GFR) of renal allograft function. The reproducibility was tested and the coefficients of variation of T 2’ values in the cortex of transplanted kidneys were 11.1 % within subjects and 11.3 % between subjects. Conclusion: Our results indicate that T 2’ imaging is a promising non-enhanced technique, which seems to reveal information on transplant function. Further studies are required to determine the clinical value of T 2’ mapping for monitoring renal allograft recipients.

Key words

transplantation - kidney - BOLD - non-contrast-enhanced MRI - susceptibility - MR functional imaging

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