| Objective:To study the predictive value of proton MR spectro-scopy of prefrontal in the elderly after abdominal surgery who will suffer from POCD.Methods:We selected 48 patients aged at least 65 years (ASAⅡ-Ⅲ) who accepted gastrointestinal tract surgery, MMSE screening of elderly patients eligible for the study cases, and selected 40 healthy aged subjects as control group. The 48 patients were accepted 1.5T superconducting MRI system with single voxel 1H-MRS examination in 1 day before and 7days after surgery, using STEAM sequence, selected parts of the same symmetry bilateral prefrontal regions of interest, ensure that the same subjects and different left and right side consistency between subjects. After the scan was completed, spectral curve,metabolite N-acetyl aspartate (NAA),choline (Cho),creatine (Cr) and the integral value were displayed in the screen. The ratios of NAA/Cr and Cho/Cr were compared between the two groups. All patients were received neuropsychological tests 1 day before and 7 days after the surgery (healthy control group two measurements separated by 7 days). Elderly patients and healthy controls were assessed using the same set of neuropsy-chological tests. The test battery included sensitive tests from the Wechsler Adult Memory Scale and Wechsler Adult Intelligence Scale, Trail Making Test (Part A)and the Grooved Pegboard Test.We use the Z score's method that ISPOCD recommended to identify postoperative cognitive dysfunction.An SD unit for each test was calculated from the healthy first scores. For patients, We compared changes in performance for each test from baseline(first session) to 7 days after surgery, and divided the result by the control-group SD to obtain a Z score for each test. Large positive Z scores showed a deterioration in cognitive function.We defined a composite Z score from all of the Z scores. Patients had cognitive dysfunction when two Z scores in individual tests or the combined Z score were 1.96 or more. We assigned all patients to POCD group or non-POCD group according to the results of neuropsychological tests. The differences in the prefrontal 1H-MRS NAA/Cr and Cho/Cr values, and analysis the predictive value of 1H-MRS detection in prefrontal to post-operative cognitive dysfunction in the elderly after abdominal surgery cognitive dysfunction on postopera-tive predictive value.Result:48 elderly patients participated in the whole process of this study, and we found cognitive dysfunction in 14(29.2%) of patients on 7th day postoperative. In the control group, all subjects completed twice neuropsychological tests, and 5%(in 2 of 40 subjects) of participants had scores that showed cognitive dysfunction. We chose the neuropsy-chological tests false positive rate of 5%. NAA/Cr,Cho/Cr of the left prefrontal were no signifinantly diffenrence compared to the right in POCD group or non-POCD; before and after surgery, there were no signifinantly diffenrence of NAA/Cr,Cho/Cr in POCD group or non-POCD group; the NAA/Cr of the bilateral prefrontal lobe between the elderly of POCD and non-POCD group were signifinantly difference(P<0.05) before and after operation, the NAA/Cr ratio was lower in the left ((1.41±0.35<1.68±0.30) and right (NAA/Crl.42±0.33<1.62±0.32) sides of POCD subjects before surgery,a decrease in the NAA/Cr radio was foud in the left (1.40±0.38<1.67±0.31) and right (1.43±0.28<1.66±0.29) sides of POCD subjects after surgery; Cho/Cr ratio between the two groups no significant difference (P>0.05).Conclusion:1 The incidence of cognitive dysfunction was 29.2% in 7days after abdominal surgery in elderly patients.2 The prefrontal NAA/Cr values of 1H-MRS detection in POCD patients decreased significantly than non-POCD. Preoperative prefrontal 'H-MRS detection is sensitive to predict for POCD in elderly after abdominal surgery. |
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