TY - JOUR
T1 - Hemodialysis increases apparent diffusion coefficient of brain water in nephrectomized rats measured by isotropic diffusion-weighted magnetic resonance imaging
AU - Galons, Jean Philippe
AU - Trouard, Ted
AU - Gmitro, Arthur F.
AU - Lien, Yeong Hau H.
PY - 1996/8/1
Y1 - 1996/8/1
N2 - The nature of brain edema in dialysis disequilibrium syndrome (DDS) was investigated by diffusion-weighted magnetic resonance imaging ((DWI). DWI was performed on normal or bilaterally nephrectomized rats before, and immediately after, hemodialysis. Hemodialysis was performed with a custom- made dialyzer (surface area 150 cm2) against a bicarbonate-buffered bath for 90 min with or without 70 mM urea. Hemodialysis with non-urea bath decreased plasma urea by 21 mM, and plasma osmolality by 22 mos-mol/kg H2O, and increased brain water content by 8.0% (all P < 0.05), while hemodialysis with urea bath did no affect plasma urea, osmolality, or brain water content. Three sets of axial DWI images of the brain were obtained at different gradient weighing factors with an in-plane resolution of 0.39 mm2. The apparent diffusion coefficient (D(app)) of the brain water was not affected by bilateral nephrectomy, or by hemodialysis in normal rats. In nephrectomized rats, brain D(app) was significantly increased after dialysis with non-urea bath (1.15 ± 0.08 vs. 0.89 ± 0.07 x 10-9m2/sec, P < 0.01). No significant changes of brain water D(app) could be observed after dialysis with urea bath. The increased D(app) associated with DDS indicates that brain extracellular water increases and/or intracellular water decreases after hemodialysis. Our results strongly suggest that the brain edema induced by hemodialysis in uremic rats is due to interstitial edema rather than cytotoxic edema. Furthermore, our results support a primary role for the 'reverse urea effect' in the pathogenesis of brain edema in DDS. DWI may be a useful diagnostic tool for DDS in patients with end-stage renal disease.
AB - The nature of brain edema in dialysis disequilibrium syndrome (DDS) was investigated by diffusion-weighted magnetic resonance imaging ((DWI). DWI was performed on normal or bilaterally nephrectomized rats before, and immediately after, hemodialysis. Hemodialysis was performed with a custom- made dialyzer (surface area 150 cm2) against a bicarbonate-buffered bath for 90 min with or without 70 mM urea. Hemodialysis with non-urea bath decreased plasma urea by 21 mM, and plasma osmolality by 22 mos-mol/kg H2O, and increased brain water content by 8.0% (all P < 0.05), while hemodialysis with urea bath did no affect plasma urea, osmolality, or brain water content. Three sets of axial DWI images of the brain were obtained at different gradient weighing factors with an in-plane resolution of 0.39 mm2. The apparent diffusion coefficient (D(app)) of the brain water was not affected by bilateral nephrectomy, or by hemodialysis in normal rats. In nephrectomized rats, brain D(app) was significantly increased after dialysis with non-urea bath (1.15 ± 0.08 vs. 0.89 ± 0.07 x 10-9m2/sec, P < 0.01). No significant changes of brain water D(app) could be observed after dialysis with urea bath. The increased D(app) associated with DDS indicates that brain extracellular water increases and/or intracellular water decreases after hemodialysis. Our results strongly suggest that the brain edema induced by hemodialysis in uremic rats is due to interstitial edema rather than cytotoxic edema. Furthermore, our results support a primary role for the 'reverse urea effect' in the pathogenesis of brain edema in DDS. DWI may be a useful diagnostic tool for DDS in patients with end-stage renal disease.
KW - brain edema
KW - nuclear magnetic resonance
KW - uremia
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U2 - 10.1172/JCI118847
DO - 10.1172/JCI118847
M3 - Article
C2 - 8698867
AN - SCOPUS:0029862108
SN - 0021-9738
VL - 98
SP - 750
EP - 755
JO - Journal of Clinical Investigation
JF - Journal of Clinical Investigation
IS - 3
ER -