The rs-fMRI study of effects of fornix and hippocampus-related brain function after the transcallosal interforniceal approach

Abstract

Background: The tumors in third ventricle are common intracranial tumors in children, characterized by various pathological types and difficult to be removed. The transcallosal interforniceal approach is often used for these tumors. The separation of bilateral fornix causes multiple surgical complications. In the past, complications could only be assessed by clinical feature and traditional imaging, lack of quantitative data to support. Resting-state functional magnetic resonance imaging (rs-fMRI) can assess brain functional connectivity between local regions and different regions in quiet state. The changes of ReHo, ALFF, fALFF and brain function connections (DMN and Hippocampus as ROI) can be used to evaluate the effects caused by operation.

Objective: To evaluate the effects of brain function caused by operation.

Methods: 9 children patients with tumors in third ventricle were randomly selected in Yuquan hospital, and scanned by rs-fMRI before and after operation. ReHo, ALFF, fALFF and function connections (DMN and Hippocampus as ROI) were chosen to analyze rs-fMRI data.

Results: The results of ReHo, ALFF, fALFF and brain function connections (DMN and Hippocampus as ROI) showed that: (1) Compared with preoperative state, ReHo decreased in left superior frontal gyrus in 1 month after operation, while increased in right middle occipital gyrus, right middle temporal gyrus, and left posterior central gyrus. In 2 months after operation, ReHo decreased in left superior temporal gyrus and right precentral gyrus compared with that in 1 month after operation. (2) Compared with preoperative state, ALFF decreased in left middle frontal gyrus and increased in left superior temporal gyrus in 1 month after operation; ALFF decreased in right fusiform gyrus and right supramarginal gyrus, while increased in left parahippocampal gyrus and left caudate nucleus in 2 months after operation. When compared with these in 1 month after operation, ALFF decreased in right fusiform gyrus and left precentral gyrus in 2 months after operation. (3) Compared with preoperative state, fALFF decreased in left superior frontal gyrus in 1 month after operation, and decreased in left middle frontal gyrus in 2 months after surgery. (4) The connections of DMN showed that enhanced connections of bilateral middle frontal gyrus and other regions in 1 month after operation, which restored to preoperative state in 3 months after operation. (5) There were changes of connections between bilateral hippocampus and related brain regions without any interruption occurred. The effects of approach can disappear in 3 months after operation.

Conclusions: The short-term effects of ReHo, ALFF and fALFF in brain regions of children patients can recover to preoperative state with time. The operation did not interrupt the connections between DMN and hippocampus related brain areas. The effects of surgery can restore to the preoperative state in 3 months after operation.

Keywords: Resting-state functional magnetic resonance imaging; The third ventricle; Transcallosal interforniceal approach; Tumor.