Prediction of acute embolic stroke outcome after local intraarterial thrombolysis: value of pretreatment and posttreatment 99mTc-ethyl cysteinate dimer single photon emission computed tomography.

The aim of this study was to investigate the efficacy of pre- and posttreatment 99mTc-ethyl cysteinate dimer (99mTc-ECD) single photon emission computed tomography (SPECT) for predicting the ischemic outcome of embolic middle cerebral artery occlusion after treatment with local intraarterial thrombolysis. The authors examined 28 patients with a moderately ischemic area (ratio of affected regional activity to cerebellar activity (A/C ratio) of 0.4 to 0.7) determined using pretreatment SPECT, and with complete recanalization within 6 hours. Posttreatment dynamic and static SPECT studies were performed immediately after thrombolysis. The extent of the affected area outlined on pretreatment SPECT was used for the posttreatment SPECT images, and A/C ratios were calculated. The relative retention ratio of 99mTc-ECD in the affected area was also analyzed using posttreatment dynamic SPECT. Fourteen patients either without infarction or with small subcortical and basal ganglial infarction, 11 patients with medium or large cortical infarction, and 3 patients with hemorrhage were identified by follow-up computed tomography. Ischemic outcome correlated with the relative retention ratio of 99mTc-ECD more closely than either the pre- or posttreatment A/C ratios. In particular, a threshold value for the development of hemorrhage was distinct only in the relative retention ratio of 99mTc-ECD. Pretreatment 99mTc-ECD SPECT did not always predict the occurrence of hemorrhagic transformation, whereas dynamic 99mTc-ECD SPECT performed immediately after thrombolysis allowed clear identification of patients at risk for hemorrhagic transformation.