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Assessment of whole-brain vasodilatory capacity with acetazolamide challenge at 1.5 T using dynamic contrast imaging
J R Petrella1, C DeCarli, M Dagli
1Laboratory of Diagnostic Radiology Research, National Institutes of Health, Bethesda, Md 20892, USA.
Purpose:
To determine whether whole-brain acetazolamide-induced changes in regional cerebral blood volume (rCBV) can be assessed on a conventional gradient 1.5-T MR system using 3-D dynamic susceptibility contrast-enhanced MR imaging.
Methods:
A 3-D frequency-shifted (FS) burst technique was used to assess the intravascular first pass of contrast agent. Changes in rCBV were calculated in 40 volunteers before and after acetazolamide (n = 30) or saline (n = 10) injection using customized analysis software on an independent workstation. A single-section gradient-echo technique with better spatial resolution was used in one additional volunteer to examine the effect of partial volume averaging on calculation of absolute rCBV.
Results:
A statistically significant increase in rCBV (gray matter = 23%, white master = 32.5%) was noted after acetazolamide compared with saline. Baseline fractional CBVs were 22% +/- 3% for gray matter and 12% +/- 2% for white matter. Partial volume averaging was probably responsible for a systematic but linear overestimation of absolute rCBV.
Conclusion:
Acetazolamide-induced changes in rCBV can be assessed using 3-D dynamic susceptibility contrast-enhanced MR imaging with FS-burst on a conventional gradient 1.5-T MR system. Values obtained with this technique overestimate absolute rCBV but are systematically biased and can be used for intersubject and intrasubject ratio comparisons.