PD06-11 REPRODUCIBILITY OF SUPRASPINAL RESPONSES TO AUTOMATED, REPETITIVE BLADDER FILLING - AN FMRI STUDY

Abstract

INTRODUCTION AND OBJECTIVES: Recent functional magnetic resonance imaging (fMRI) studies revealed supraspinal networks in response to bladder filling involved in perception and processing of bladder distension. However, reproducibility of blood-oxygenation-level dependent (BOLD) signal changes during bladder filling has not been proven yet. Therefore, our aim was to investigate BOLD signal changes in response to bladder filling to provide evidence for repeatability using a standardized filling paradigm, i.e. a magnetic resonance (MR)compatible and MR-synchronized infusion-drainage system. METHODS: 20 right-handed healthy subjects, 10 women and 10 men, mean age 39 years (range 22-54) with no history of urinary urgency and/or urinary incontinence were included. Visit 1: After catheterization and bladder pre-filling with body warm saline until persistent desire to void, we performed in a 3T MR scanner automated, repetitive bladder filling of 100mL body warm saline over 15s, i.e. block design study. Visit 2: Within 8 weeks from visit 1, a second MR scan was performed in the same manner. Using SPM8, BOLD signal changes during bladder filling were compared to rest, i.e. pre-filled condition. For within-group whole-brain (WB) analysis, a voxel-threshold was set at p<0.001 using the false discovery rate (FDR) correction to adjust for multiple comparisons. Differences between both visits were investigated using a paired t test. In addition, regions of interest (ROI) were defined using the Wake Forrest University Pickatlas and included as a mask in order to restrict the voxel-by-voxel statistical analysis (familywise error (FWE)-correction) to pre-specified brain areas. RESULTS: Within-group WB analysis revealed activation in the following brain areas for visit 1: bilateral prefrontal gyrus (PFG); anterior cingulate cortex (ACC), mid and posterior cingulate cortex; left insula; hippocampus; temporal and parietal gyrus; and for visit 2: bilateral PFG; ACC; bilateral insula; bilateral basal ganglia. No statistical differences in BOLD signal changes were detected between both visits. ROI analyses, a more sensitive approach, detected reproducibility of BOLD signal changes in the following areas: PFG, ACC and insula. CONCLUSIONS: This study confirms that automated, repetitive bladder filling of body warm saline using a MR-compatible and MRsynchronized infusion-drainage system shows reproducible BOLD signal changes in specific areas, known from previous neuroimaging studies to be involved in supraspinal lower urinary tract control.