ASSESSMENT OF WHOLE-BRAIN VASODILATORY CAPACITY WITH ACETAZOLAMIDE CHALLENGE AT 1.5 T USING DYNAMIC CONTRAST IMAGING WITH FREQUENCY-SHIFTEDBURST

PURPOSE: To determine whether whole-brain acetazolamide-induced change s in regional cerebral blood volume (rCBV) can be assessed on a conven tional gradient 1.5-T MR system using 3-D dynamic susceptibility contr ast-enhanced MR imaging, METHODS: A 3-D frequency-shifted (FS) burst t echnique was used to assess the intravascular first pass of contrast a gent, Changes in rCBV were calculated in 40 volunteers before and afte r acetazolamide (n = 30) or saline (n = 10) injection using customized analysis software on an independent workstation. A single-section gra dient-echo technique with better spatial resolution was used in one ad ditional volunteer to examine the effect of partial volume averaging o n calculation of absolute rCBV, RESULTS: A statistically significant i ncrease in rCBV (gray matter = 23%, white matter = 32.5%) was noted af ter acetazolamide compared with saline. Baseline fractional CBVs were 22% +/- 3% for gray matter and 12% +/- 2% for white matter. Partial vo lume averaging was probably responsible for a systematic but linear ov erestimation of absolute rCBV. CONCLUSION: Acetazolamide-induced chang es in rCBV can be assessed using 3-D dynamic susceptibility contrast-e nhanced MR imaging with FS-burst on a conventional gradient 1.5-T MR s ystem. Values obtained with this technique overestimate absolute rCBV but are systematically biased and can be used for intersubject and int rasubject ratio comparisons.