Absolute quantification of cerebral blood flow in normal volunteers: correlation between Xe-133 SPECT and dynamic susceptibility contrast MRI.
OBJECTIVE
To compare absolute cerebral blood flow (CBF) estimates obtained by dynamic susceptibility contrast MRI (DSC-MRI) and Xe-133 SPECT.


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)).


CONCLUSIONS
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).
Knutsson
Linda
L
Center for Medical Imaging and Physiology, MR division, Lund University Hospital, Lund, Sweden. Linda.Knutsson@med.lu.se
Börjesson
Siv
S
Larsson
Elna-Marie
EM
Risberg
Jarl
J
Gustafson
Lars
L
Passant
Ulla
U
Ståhlberg
Freddy
F
Wirestam
Ronnie
R
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology / Q000473:pathology; D002560:Cerebrovascular Circulation; D003287:Contrast Media / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014980:Xenon Radioisotopes / Q000494:pharmacology*
D003287:Contrast Media; D014980:Xenon Radioisotopes