[en] Changes of canine brain T₁s measured in right and left white (W-T₁) and gray (G-T₁) matter, thalamus (T-T₁), and caudate nucleus (C-T₁) in coronal view with a head coil was studied in anesthesized and automatically ventilated 11 mongrel dogs (9.2±2.2 kg) using 0.1 T MR imager (Mark-J, Siemens-Asahi Meditech) before and every 30 minutes after infusion of distilled water warmed at 37degC into abdominal cavity (192±50 ml/kg) up to 120 minute later. Hemolysis (2→85 mg/dl: before→after 120 min) increased in association with total protein (5.9→8.0 g/dl) while sodium (147→122 mEq/l) and osmolarity (302→263 mOsm/kg) decreased. G-T₁ (388→394 ms) and W-T₁ (287→305 ms) did not change significantly, but T-T₁ prolonged early (331→349 ms) at 60 min (p<0.05) and C-T₁ (356→376 ms) did at 90 min (p<0.05). T-T₁ (363 ms) and C-T₁ (382 ms) elongated from initial each T₁ significantly (p<0.01) 7% and 6% at 120 min, respectively. Basal nuclei, especially thalamus, in canine brain became edematous at the early stage of hyponatremic hypoosmosis induced by peritoneal dialysis with water. (author)