Neuroscience 2000 Abstract
| Presentation Number: | 490.7 |
|---|---|
| Abstract Title: | Absolute cerebral MTT with perfusion MRI. |
| Authors: |
DeLucia-Deranja, E.*1
; Tudorica, A.1
; Patlak, C.1
; Li, H.1
; Hospod, F.1
; Newman, G.1
1Department of Pharmacology, SUNY at Stony Brook, Stony Brook, NY |
| Primary Theme and Topics |
H. Other Systems of the CNS - 101. Brain metabolism and blood flow |
| Session: |
490. Cognition: methods and models I Slide |
| Presentation Time: | Tuesday, November 7, 2000 2:30 PM-2:45 PM |
| Location: | Room 262 |
| Keywords: | BLOOD FLOW, MTT, MRI, PERFUSION |
There is still no practical, theoretically sound method for directly measuring cerebral mean transit time (MTT) from MRI data 1,2. We have derived a novel theory for measuring MTT suitable for perfusion MRI data and tested this theory in dogs. The theory shares the assumptions of the central volume theorem for an inert, intravascular tracer but also assumes that the system can be described by a single mean path with a single MTT for each ROI. After fitting the perfusion data for tissue and artery to a gamma variate function, it can be shown that MTT is found by solving the non-linear equation (1 - exp(- MTT / tart)) / (MTT / tart) = tart)/ ttis, where the peak in the arterial curve is at time t art, the peak in the tissue curve is at time (ttis+ ΔAT) and ΔAT is the difference in contrast arrival times between artery and tissue. Male, 15 kg, purpose-bred hounds (n = 6) were anesthetized with IV acepromazine and pentobarbital. MRI sequences were acquired on a 1.5 T Picker Edge and included single shot echo planar T2*-weighted images over 45-60 sec during and after IV bolus injection of gadodiamide. Among the 22 experiments, TR ranged from 300 - 1000 msec (TE 52 msec) and contrast dosage from 25 to 150 μmol / kg. Unfiltered arterial and tissue ROIs were analyzed on a pixel by pixel basis using interactive software to minimize volume averaging. Effects of Dose and TR were compared by MANOVA. MTT ranged from 1.7 to 5.6 sec with a mean ± SE of 3.2 ± 0.2 sec. There were no significant effects of either TR or Dose on MTT. This theory permits MTT to be calculated directly using tart, ttis and ΔAT from the fitted arterial and tissue gamma variate curves. No deconvolution is necessary. Assuming a reasonable estimate of 4% for CBV, this MTT would yield a CBF value of 74.8 ml/100g/min, which correlates well with prior CBF measurements in the dog 3. 1. JCereb Blood Flow Metab 1998; 18:425. 2. MRM 1993;29:553. 3. Anesth Analg 1991;72:75.
Supported by Marconi Medical Systems and our MR Research Center.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2000 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2000. Online.
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