HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JNM Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Weber, B. Articles by Buck, A. Search for Related Content PubMed PubMed Citation Articles by Weber, B. Articles by Buck, A.

Constant-Infusion H₂¹⁵O PET and Acetazolamide Challenge in the Assessment of Cerebral Perfusion Status

¹ Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
² Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland

View larger version (12K): [in a new window]   FIGURE 1. Normalized response of Ctiss to a rectangular flow change (A) and a more physiologic flow change (B). In A, flow was assumed to change from 50 to 100 and back to 50 mL/min/100 mL. In B, the curves were calculated as follows: First, the calculated cerebellar time course of CBF after ACZ of 1 patient was approximated by the equation CBFsim = CBFbase + CBF(1 – e–ln2/Txt), where baseline CBF (CBFbase) = 50 mL/min/100 g, CBF = 50 mL/min/100 g, and time (T) = 165 s. Simulated CBF (CBFsim) was then assumed to be true CBF (CBFtrue). CBFtrue and a constant ca were fed into Equation 1 to calculate a simulated time course of Ctiss (Ctiss sim). Ctiss sim was then back-converted to CBFc values using the equilibrium equation, Equation 4. For display purposes, all values were normalized to baseline and expressed as a percentage. The deviation of CBFc from CBFtrue is, at maximum, 13% (2 min after ACZ).

View larger version (69K): [in a new window]   FIGURE 2. Assessment of cerebral perfusion status of patient 1, with left-sided internal carotid artery stenosis. Images at top demonstrate placement of VOIs. Images on left represent the mean H215O concentration of 5 consecutive 1-min frames in transaxial slices through the territory of the middle cerebral artery. On right are parametric images in which CBF is calculated voxel by voxel. Although perfusion is symmetric at baseline, the increase in the territory of the left middle cerebral artery is reduced after ACZ. The subtraction image was filtered using a 3-dimensional gaussian kernel of 10 mm in full width at half maximum. The reduced increase of CBF is more evident on the parametric images.

View larger version (35K): [in a new window]   FIGURE 3. Tissue time–activity curves for patients 1–4, with stenosis of the internal carotid artery. The graphs on the left demonstrate the tissue time–activity curves normalized to the mean of the cerebellum. The graphs on the right demonstrate the time course of CBFc.

View larger version (37K): [in a new window]   FIGURE 4. Tissue time–activity curves for patients 5–10, with moyamoya disease. The graphs on the left demonstrate the tissue time–activity curves normalized to the mean of the cerebellum. The graphs on the right demonstrate the time course of CBFc. MCA = middle cerebral artery.

View larger version (30K): [in a new window]   FIGURE 5. Time course of the ratio CBFcortex/CBFcerebellum for the 10 patients.

View larger version (30K): [in a new window]   FIGURE 6. Bland–Altman plot of the reproducibility of the baseline scans. Two differences were analyzed: scan 2 – scan 1 (•) and scan 4 – scan 3 (). The differences are presented as the percentage of the mean of the 2 scans. The horizontal line is the mean difference of all data points, and the shaded area represents mean ± 2 SDs.