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Patlak plots of Gd‐DTPA MRI data yield blood–brain transfer constants concordant with those of 14 C‐sucrose in areas of blood–brain opening
The blood‐to‐brain transfer rate constant (K i ) of Gd‐DTPA was determined in MRI studies of a rat model of transient cerebral ischemia. The longitudinal relaxation rate, R 1 , was estimated using repeated Look‐Locker measurements. A model‐independent analysis of ΔR 1 , the Patlak plot, produced map...
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Published in: | Magnetic resonance in medicine 2003-08, Vol.50 (2), p.283-292 |
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Main Authors: | , , , , , , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The blood‐to‐brain transfer rate constant (K
i
) of Gd‐DTPA was determined in MRI studies of a rat model of transient cerebral ischemia. The longitudinal relaxation rate, R
1
, was estimated using repeated Look‐Locker measurements. A model‐independent analysis of ΔR
1
, the Patlak plot, produced maps of K
i
for Gd‐DTPA and the distribution volume of the mobile protons (V
p
) with intravascular‐Gd changed R
1
's. The K
i
's of Gd‐DTPA were estimated in regions of interest with blood–brain barrier (BBB) opening (regions of interest, ROIs) and compared to those of
14
C‐sucrose determined shortly thereafter by quantitative autoradiography. The K
i
's for both Gd‐DTPA and sucrose were much higher than normal within the ROIs (n = 7); linear regression of K
i
for Gd‐DTPA vs. K
i
for sucrose yielded a slope of 0.43 ± 0.11 and r
2
= 0.72 (
P
= 0.01). Thus, K
i
for Gd‐DTPA varied in parallel with, but was less than, K
i
for sucrose. In the ROIs, mean V
p
was 0.071 ml g
−1
and much higher than mean vascular volume estimated by dynamic‐contrast‐enhancement (0.013 ml g
−1
) or mean V
p
in contralateral brain (0.015 ml g
−1
). This elevated V
p
may reflect increased capillary permeability to water. In conclusion, K
i
can be reliably calculated from Gd‐DTPA‐MRI data by Patlak plots. Magn Reson Med 50:283–292, 2003. © 2003 Wiley‐Liss, Inc. |
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ISSN: | 0740-3194 1522-2594 |
DOI: | 10.1002/mrm.10524 |