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Absolute quantification of cerebral blood flow in normal volunteers: correlation between Xe-133 SPECT and dynamic susceptibility contrast MRI.

Knutsson L, Börjesson S, Larsson EM, Risberg J, Gustafson L, Passant U, Ståhlberg F, Wirestam R

Center for Medical Imaging and Physiology, MR division, Lund University Hospital, Lund, Sweden. Linda.Knutsson@med.lu.se

PURPOSE: To compare absolute cerebral blood flow (CBF) estimates obtained by dynamic susceptibility contrast MRI (DSC-MRI) and Xe-133 SPECT. MATERIALS AND METHODS: CBF was measured in 20 healthy volunteers using DSC-MRI at 3T and Xe-133 SPECT. DSC-MRI was accomplished by gradient-echo EPI and CBF was calculated using a time-shift-insensitive deconvolution algorithm and regional arterial input functions (AIFs). To improve the reproducibility of AIF registration the time integral was rescaled by use of a venous output function. In the Xe-133 SPECT experiment, Xe-133 gas was inhaled over 8 minutes and CBF was calculated using a biexponential analysis. RESULTS: The average whole-brain CBF estimates obtained by DSC-MRI and Xe-133 SPECT were 85 +/- 23 mL/(min 100 g) and 40 +/- 8 mL/(min 100 g), respectively (mean +/- SD, n = 20). The linear CBF relationship between the two modalities showed a correlation coefficient of r = 0.76 and was described by the equation CBF(MRI) = 2.4 . CBF(Xe)-7.9 (CBF in units of mL/(min 100 g)). CONCLUSION: A reasonable positive linear correlation between MRI-based and SPECT-based CBF estimates was observed after AIF time-integral correction. The use of DSC-MRI typically results in overestimated absolute perfusion estimates and the present study indicates that this trend is further enhanced by the use of high magnetic field strength (3T).

Published 1 October 2007 in J Magn Reson Imaging, 26(4): 913-20.
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