PURPOSE: To determine whether the human retinal oxygenation response (deltaPO2) to a hyperoxic provocation is abnormal in patients with type I diabetes. METHODS: Magnetic resonance imaging (MRI) was used to measure deltaPO2 during 100% oxygen breathing in patients with type I diabetes who had either no clinically detectable retinopathy (n = 5) or mild to moderate background diabetic retinopathy (BDR; n = 5) and in age-matched healthy control subjects (n = 7). RESULTS: Both the patients with diabetes and the control subjects exhibited a significant (P < 0.05) increase in the preretinal vitreous signal intensity on changing from room air breathing to oxygen inhalation (i.e., 5 minutes). However, only diabetic patients demonstrated significant (P < 0.05) increases in deltaPO2 between measurements made at 5 minutes of oxygen inhalation and measurements at longer durations of hyperoxia (15, 25, and 35 minutes). Furthermore, deltaPO2 was significantly (P < 0.05) greater in patients with diabetes than in control subjects, but there was no significant difference in deltaPO2 (P > 0.05) between patients with diabetes, with or without retinopathy. Age and deltaPO2 correlated significantly (P < 0.05) in control subjects but not in patients with diabetes. In control subjects, deltaPO2 was relatively uniform panretinally, whereas in the diabetic group, changes in oxygenation response were spatially inhomogeneous. CONCLUSIONS: These results demonstrate, for the first time, that MRI deltaPO2 detects a significant supernormal retinal oxygenation response in patients with type I diabetes, even before the appearance of retinopathy. This study raises the possibility of using MRI measurements of deltaPO2 to monitor therapeutic efficacy in human trials.
PURPOSE: To determine whether the human retinal oxygenation response (deltaPO2) to a hyperoxic provocation is abnormal in patients with type I diabetes. METHODS: Magnetic resonance imaging (MRI) was used to measure deltaPO2 during 100% oxygen breathing in patients with type I diabetes who had either no clinically detectable retinopathy (n = 5) or mild to moderate background diabetic retinopathy (BDR; n = 5) and in age-matched healthy control subjects (n = 7). RESULTS: Both the patients with diabetes and the control subjects exhibited a significant (P < 0.05) increase in the preretinal vitreous signal intensity on changing from room air breathing to oxygen inhalation (i.e., 5 minutes). However, only diabeticpatients demonstrated significant (P < 0.05) increases in deltaPO2 between measurements made at 5 minutes of oxygen inhalation and measurements at longer durations of hyperoxia (15, 25, and 35 minutes). Furthermore, deltaPO2 was significantly (P < 0.05) greater in patients with diabetes than in control subjects, but there was no significant difference in deltaPO2 (P > 0.05) between patients with diabetes, with or without retinopathy. Age and deltaPO2 correlated significantly (P < 0.05) in control subjects but not in patients with diabetes. In control subjects, deltaPO2 was relatively uniform panretinally, whereas in the diabetic group, changes in oxygenation response were spatially inhomogeneous. CONCLUSIONS: These results demonstrate, for the first time, that MRI deltaPO2 detects a significant supernormal retinal oxygenation response in patients with type I diabetes, even before the appearance of retinopathy. This study raises the possibility of using MRI measurements of deltaPO2 to monitor therapeutic efficacy in human trials.
Authors: Rod D Braun; Marius Gradianu; Kerry S Vistisen; Robin L Roberts; Bruce A Berkowitz Journal: Invest Ophthalmol Vis Sci Date: 2007-03 Impact factor: 4.799
Authors: Kathryn Richdale; Peter Wassenaar; Katharine Teal Bluestein; Amir Abduljalil; John A Christoforidis; Titus Lanz; Michael V Knopp; Petra Schmalbrock Journal: J Magn Reson Imaging Date: 2009-11 Impact factor: 4.813