Contributions of dynamic venous blood volume versus oxygenation level changes to BOLD fMRI

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• 作者：Xiaopeng Zong ; Tae Kim ; ^{tak19@pitt.edu} ; Seong-Gi Kim
• 关键词：CBV ; BOLD ; BOLD undershoot ; Cerebral arterial blood volume ; Cerebral venous blood volume ; Venous oxygenation level
• 刊名：NeuroImage
• 出版年：2012
• 期刊代码：83_10538119
• 类别：neu
• 出版时间：1 May, 2012
• 卷：60
• 期：4
• 页码：2238-2246
• 文件大小：792 K

摘要

Blood-oxygenation-level-dependent (BOLD) fMRI has contributions from venous oxygenation and venous cerebral blood volume (CBV) changes. To examine the relative contribution of venous CBV change (螖CBV_v) to BOLD fMRI, BOLD and arterial CBV changes (螖CBV_a) to a 40-s forepaw stimulation in six 伪-chloralose anesthetized rats were measured using a magnetization transfer-varied fMRI technique, while total CBV change (螖CBV_t) was measured with injection of iron oxide nanoparticles. 螖CBV_v was obtained by subtracting 螖CBV_a from 螖CBV_t. We observed a fast 螖CBV_a response with a time constant of 2.9 卤 2.3 s and a slower 螖CBV_v response with a time constant of 13.5 卤 5.7 s and an onset delay of 6.1 卤 3.3 s. These results are consistent with earlier studies under different anesthesia and stimulus, supporting that fast CBV_a and slow CBV_v responses are generalizable. Assuming the observed post-stimulus BOLD undershoot is at least partly explained by the 螖CBV_v contribution, the relative contribution of the 螖CBV_v- and oxygenation-change-related components to the BOLD response was estimated. The relative 螖CBV_v contribution increases with time during stimulation; whereby it is < 0.14 during initial 10 s and reaches a maximum possible value of ~ 0.45 relative to the oxygenation contribution during the 30-40 s period after stimulus onset. Our data indicates that the contribution of venous oxygenation change to BOLD fMRI is dominant for short stimulations.