Dynamic and static 99mTc-ECD SPECT imaging of subacute cerebral infarction: comparison with 133Xe SPECT.
99mTc-ethylcysteinate dimer (99mTc-ECD) SPECT imaging reportedly fails to show reflow hyperemia in patients with subacute stroke. This study attempts to determine the clinical usefulness of dynamic 99mTc-ECD SPECT in evaluating regional blood flow in subacute cerebral infarction and the kinetic behavior of 99mTc-ECD in infarct areas.


METHODS
133Xe and consecutive dynamic and static 99mTc-ECD SPECT studies were performed on 24 patients with cortical infarction in the middle cerebral artery territory 13-15 d after the onset of a stroke. Image contrast between infarct and contralateral control areas on 99mTc-ECD tomograms (ECD uptake ratio) was compared with that on cerebral blood flow (CBF) images obtained using 133Xe inhalation (CBF ratio).


RESULTS
In all cases, ECD uptake ratios from static images were lower than CBF ratios. This tendency was obvious when CBF in the infarct area increased above the normal control value, and no significant correlation was found between ECD uptake ratios from static images and CBF ratios. Only in the infarct areas with CBF below the normal control value, however, was a significant correlation between the two maintained (r = 0.795; P = 0.0011). A very strong correlation was found between CBF ratios and ECD uptake ratios on both the first dynamic scan (36 s after injection) (r = 0.991; P < 0.0001) and the second dynamic scan (72 s after injection) (r = 0.945; P < 0.0001). The correlation coefficient decreased in a time-dependent manner, with no significant correlation observed after the fourth dynamic scan (144 s after injection). On the other hand, significant correlations were observed on all dynamic scans only in the infarct areas with CBF below the control value.


CONCLUSIONS
Super-early images of dynamic 99mTc-ECD SPECT provide a close imaging contrast with CBF and reveal reflow hyperemia in areas with irreversible changes produced by subacute stroke, which static 99mTc-ECD SPECT images fail to show. Decreased retention of the tracer in the infarct areas with hyperperfusion causes an underestimation of CBF on static 99mTc-ECD SPECT images. Given these results, we believe that dynamic 99mTc-ECD SPECT is an effective clinical tool to evaluate regional blood flow in subacute cerebral infarction.
Ogasawara
K
K
Department of Neurosurgery and High-Technology Medical Research Center, Iwate Medical University, Morioka, Japan.
Ogawa
A
A
Ezura
M
M
Konno
H
H
Doi
M
M
Kuroda
K
K
Yoshimoto
T
T
D000328:Adult; D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging; D003545:Cysteine / Q000031:analogs & derivatives; D005260:Female; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods; D014980:Xenon Radioisotopes
D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D014980:Xenon Radioisotopes; C059659:technetium Tc 99m bicisate; D003545:Cysteine