Study of ~(99m)Tc-ECD brain SPECT imaging with acetazolamide and its application in cerebrovascular diseases

Objective To develop a routine procedure of the acetazolamide (ACZ) test,to obtain the normal values of cerebral blood flow (CBF) response to ACZ,to enhance the sensitivity and accuracy of detecting ischemic cerebral vascular disease and to find criteria for evaluation of CBF reserve. Methods Brain 99m Tc ECD CBF and SPECT studies before and after (lg,i. v.,20min postinjection) were performed on 6 normal subjects,32 cases with TIA or RIND and 11 cases with small infarcts. CT was performed on all patients and MRI,TCD or DSA on some of them. Image analysis:(1)Three types of response to were defined visually: type A (poor response),low focal CBF appearing after ACZ(type A 1) or low focal CBF increasing in size (type A 2);type B (good response),normal or low focal CBF and type C, with no change after ACZ. (2)Semiquantitative analysis:① Measurement of the peak time of carotid arteries and hemispheres and also the △% of hemispheric CBF per global CBF derived from the time activity curve of radionuclide cerebral angiography (RNCA);②Measurement of the rCBF increase and the uptake ratio (UR) of the affected/unaffected areas and hemispheres before and after ACZ. Results (1)Normal values there were no differences between the peak times△% of hemispheric CBF per global CBF of both sides. The mean △% after was 25.07%±8.09%. The UR of all regions was0.90.(2)42% of the TIA patients had occlusive cerebrovascular disease,as detected by RNCA. This result correlated well with that of TCD and DSA. (3)The detection rate of TIA was increased from 59.37% (baseline) to 87.15% (after ACZ) and that of small infarcts from 73% to 90%. (4)The vascular reserve was poor in type A patients and their therapeutic effect was also poor. The vascular reserve in type B patients was good and the therapeutic effect of this type was good too. (5)Hypoperfusion in the thalamus and (or) cerebellum in patients with small infarcts all recovered to normal perfusion after injection. Conclusion ACZ test is a safe reliable interventional modality of cerebral perfusion SPECT imaging. In cerebrovascular disease,it is useful to evaluate the cerebral vascular reactivity of the patients and the visual type of respone may be helpful to decide the therapeutic plan and to predict the therapeutic effect on these patients.