Quantitative perfusion imaging with pulsed arterial spin labeling: a phantom study.
OBJECTIVE
Pulsed arterial spin labeling (PASL) is a magnetic resonance (MR) method for measuring cerebral blood flow. Although several validation studies for PASL in animals and humans have been reported, no reports have detailed the fundamental study of PASL using a flow phantom. We compared the true and theoretical flow rates in a flow phantom to confirm the analytical validity of quantitative perfusion imaging with Q2TIPS sequence.


METHODS
We built a flow phantom consisting of a 40-mm diameter plastic syringe filled with plastic beads and small plastic tubes 4 mm in diameter. Gd-DTPA-doped 8L water solution (0.1 mM) was circulated between the syringe and a tank through a plastic tube by a constant flow pump while the flow rate was adjusted between 0 and 2.61 cm/s. Q2TIPS sequence parameters were TI(1)=50 ms and TI(2)=1400 ms. Five imaging slices of 50 subtraction images were acquired sequentially in a distal-to-proximal direction using a single-shot echo planar imaging (EPI) technique. The theoretical flow rate calculated based upon the previously reported kinetic model for Q2TIPS was compared with the true flow rate.


RESULTS
A good linear relationship was observed between the theoretical, F', and true flow rates, F, in a flow rate range of 1.43 to 1.95 cm/s (F'=1.024*F-1.915, R(2)=0.902). The ratio of theoretical to true flow rate was 92 (+/-) 4%.


CONCLUSIONS
Flow rate was quantified with reasonable accuracy when the entire amount of labeled bolus within the phantom could be recovered. Our experiment confirmed the analytical validity of Q2TIPS and suggested that blood flow measurement may be feasible using the Q2TIPS pulse sequence and kinetic model of the PASL equation.
Noguchi
Tomoyuki
T
Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. tnogucci@radiol.med.kyushu-u.ac.jp
Yoshiura
Takashi
T
Hiwatashi
Akio
A
Togao
Osamu
O
Yamashita
Koji
K
Kobayashi
Kouji
K
Mihara
Futoshi
F
Honda
Hiroshi
H
D001783:Blood Flow Velocity; D002560:Cerebrovascular Circulation; D003287:Contrast Media / Q000008:administration & dosage; D017352:Echo-Planar Imaging / Q000295:instrumentation / Q000379:methods*; D005240:Feasibility Studies; D019786:Gadolinium DTPA / Q000008:administration & dosage; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000295:instrumentation / Q000379:methods*; D008954:Models, Biological; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D013113:Spin Labels
D003287:Contrast Media; D013113:Spin Labels; D019786:Gadolinium DTPA