Evaluation of metabolite?s changes in visual cortex in diabetic retinopathy by mr-spectroscopy

PURPOSE: To evaluate metabolite?s changes in the visual cortex of diabetic patients with nonproliferative or proliferative diabetic retinopathy by MR spectroscopy.MATERIAL AND METHODS: 15 patients with presbyopia (group 1), 15 patients with diabetes who didn?t have diabetic retinopathy (group 2), 15 patients with nonproliferative diabetic retinopathy (NPDR) (group 3), 15 patients with proliferative diabetic retinopathy (PDR) (group 4) were included in the study. Furthermore, diabetic patients was divided into two groups according to HbA1c levels (Group A: 20 patients, HbA1c <8%; Group B: 20 patients, HbA1c>8%). In the all of cases? left visual cortex, amounts of N-acetyl-aspartate (NAA), choline (Cho) and creatine (Cr) were measured by MR spectroscopy. NAA/Cr, Cho/Cr and NAA/Cho ratios were calculated. Furthermore, all cases? CBC and biochemical parameters were evaluated.RESULTS: The mean NAA/Cr, Cho/Cr and NAA/Cho ratios were 1.72±0.33, 0.70±0.13, 2.53±0.88, respectively in the visual cortex of group 1. The mean NAA/Cr, Cho/Cr and NAA/Cho ratios were 1.65±0.22, 0.65±0.09, 2.56±0.51, respectively in the visual cortex of group 2. The mean NAA/Cr, Cho/Cr and NAA/Cho ratios were 1.59±0.31, 0.72±0.14, 2.29±0.75, respectively in the visual cortex of group 3. The mean NAA/Cr, Cho/Cr and NAA/Cho ratios were 1.49±0.17, 0.68±0.12, 2.22±0.46, respectively in the visual cortex of group 4. There was no statistically significant difference for NAA/Cr, Cho/Cr, NAA/Cho ratios between group 1, 2, 3 and 4 (p>0.05). The mean NAA/Cr, Cho/Cr and NAA/Cho ratios were 1.70±0.21, 0.65±0.10, 2.62±0.57, respectively in the visual cortex of group A. The mean NAA/Cr, Cho/Cr and NAA/Cho ratios were 1.46±0.20, 0.73±0.12, 2.05±0.42, respectively in the visual cortex of group B. There were a statistically significant difference for NAA/Cr and NAA/Cho ratios between group A and B (P<0.05). There was no statistically significant difference for Cho/Cr ratio between group A and B (P>0.05).CONCLUSION: There are a decrease in the NAA/Cr and NAA/Cho ratios in the visual cortex while diabetic retinopathy progresses. But, these decreases aren?t statistically significant. While HbA1c levels increases the NAA concentration decreases in the visual cortex which indicates neuronal loss. The metabolite?s changes in the visual cortex is associated with acute events rather chronic events.