Absolute cerebral blood flow measured by dynamic susceptibility contrast MRI: a direct comparison with Xe-133 SPECT

Abstract

Absolute regional cerebral blood flow (CBF) was measured in ten healthy volunteers, using both dynamic susceptibility-contrast (DSC) magnetic resonance imaging (MRI) and Xe-133 SPECT within-4 h. After i.v. injection of Gd-DTPA-BMA (0.3 mmol/kg b.w.), the bolus was monitored with a Simultaneous Dual FLASH pulse sequence (1.5 s image), providing one slice through brain tissue and a second slice through the carotid artery. ConcentrationC(t)x − (1 TE) ln[S(t)/S(0)] was related to CBF asC(t)=CBF [AIF(t)⊗R(t)], where AIF is the arterial input function andR(t) is the residue function. A singular-value-decomposition-based deconvolution technique was used for retrieval ofR(t). Absolute CBF was given by Zierler’s area-to-height relation and the central volume principle. For elimination of large vessels (ELV), all MRI-based CBF values exceeding 2.5 times the mean CBF value of the slice were excluded. A correction for partial-volume effects (CPVE) in the artery used for AIF monitoring was based on registration of signal in a phantom with tubes of various diameters (1.5–6.5 mm), providing an individual concentration correction factor applied to AIF data registered in vivo. In the Xe-133 SPECT investigation, 3000–4000 MBq of Xe-133 was administered intravenously, and CBF was calculated using the Kanno-Lassen algorithm. When ELV and CPVE were applied. DSC-MRI showed average CBF values from the entire slice of 43±10 ml/(min 100 g) (small-artery AIF) and 48±17 ml (min 100 g) (carotid-artery AIF) (mean±S.D.,n=10). The corresponding Xe-133-SPECT-based CBF was 33±6 ml (min 100 g) (n=10). The relationships of CBF(MRI) versus CBF(SPECT) showed good linear correlation (r=0.74–0.83).