The significance of BOLD MRI in differentiation between renal transplant rejection and acute tubular necrosis.
BACKGROUND
Blood oxygen level-dependent MRI (BOLD MRI) can be used to assess intra-renal oxygen bioavailability by measuring the R2(*) level, which reflects tissue deoxyhaemoglobin levels. This study was designed to identify the significance of BOLD MRI in differentiation of acute rejection (AR) and acute tubular necrosis (ATN) in patients within 6 months after kidney transplantation.


METHODS
Eighty-two patients with normal graft function and 28 patients with biopsy-proven AR (n = 21) or ATN (n = 7) were enrolled. Patients with normal functioning allograft underwent BOLD MRI within 2 to 3 weeks post-transplantation, while patients with AR and ATN underwent BOLD MRI within 6 days before or after kidney transplant biopsy. Cortical R2(*) (CR2(*)) and medullary R2(*) (MR2(*)) levels were measured.


RESULTS
The mean CR2(*) level was significantly higher in the ATN group (15.25 +/- 1.03/s) compared to the normal group (13.35 +/- 2.31/s, P = 0.028) and AR group (12.02 +/- 1.72/s, P = 0.001). There was a significant difference also between the AR group and normal group on CR2(*) levels (P = 0.013). The mean MR2(*) level was significantly lower in the AR group (14.02 +/- 2.68/s) compared to the normal group (16.66 +/- 2.82/s, P < 0.001) and ATN group (19.47 +/- 1.62/s, P < 0.001). There was also a significant difference between the ATN group and normal group on MR2(*) levels (P = 0.011). There were no correlations between characteristics such as patient age, post-operation time, post-biopsy time, Scr level, HB level, urine output volume, MAP level, CNI trough concentration and R2(*) levels, except between MAP level and CR2(*) level (P = 0.029).


CONCLUSIONS
BOLD MRI could be a valuable method to discriminate between AR and ATN by measuring tissue oxygen bioavailability in early kidney allograft dysfunction.
Han
Fei
F
Kidney Disease Center, The First Affiliated Hospital, College of Medicine, Zhejiang University, People's Republic of China.
Xiao
Wenbo
W
Xu
Ying
Y
Wu
Jianyong
J
Wang
Qidong
Q
Wang
Huiping
H
Zhang
Minming
M
Chen
Jianghua
J
D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D006084:Graft Rejection / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000098:blood supply / Q000503:physiopathology; D016030:Kidney Transplantation / Q000009:adverse effects* / Q000473:pathology* / Q000502:physiology; D007683:Kidney Tubular Necrosis, Acute / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood* / Q000378:metabolism
D006454:Hemoglobins; C100003:deoxyhemoglobin; D010100:Oxygen