technetium-tc-99m-bicisate and Reperfusion-Injury

It is unclear from recent clinical trials whether thrombolytic agents are capable of facilitating reperfusion and metabolic recovery over time or whether a beneficial effect is counteracted by an increase in the risk of brain hemorrhage. We studied the effect of thrombolytic treatment on metabolic recovery after reperfusion and clinical outcome.. Patients were prospectively studied with (99m)Tc-ethyl cysteinate dimer single photon emission computed tomography ((99m)Tc-ECD-SPECT) before treatment with recombinant tissue plasminogen activator (rTPA; 0.9 mg/kg IV; n=26) or placebo (n=26) 6 to 8 hours after treatment and at 7+/-1 days. Activity deficits were graded, compared between the treatment groups, and correlated with clinical outcome and the incidence of brain hemorrhage. Metabolic recovery of ischemic brain tissue was defined as a 25% decrease on the SPECT graded scale.. Patients with metabolic recovery (n=28) had a better chance of being functionally unimpaired 3 months after stroke than patients without recovery (n=24) (OR 4.5, 95% CI 1.09 to 18.89) and had smaller infarcts on follow-up CT (36+/-38 versus 167+/-162 mL), regardless of whether metabolic recovery was observed within 6 to 8 hours of treatment or at 7 days. None of the 28 patients with metabolic recovery had a fatal parenchymal hemorrhage versus 5 of 24 patients without recovery (P=0.016). Treatment did not affect the incidence of brain tissue metabolic recovery.. Brain tissue metabolic recovery after ischemic stroke was associated with a beneficial effect on clinical outcome and was not facilitated by treatment with 0.9 mg of intravenous rTPA.

Topics: Aged; Brain; Brain Ischemia; Cysteine; Female; Fibrinolytic Agents; Follow-Up Studies; Humans; Male; Middle Aged; Organotechnetium Compounds; Radiopharmaceuticals; Reperfusion Injury; Stroke; Thrombolytic Therapy; Tissue Plasminogen Activator; Tomography, Emission-Computed, Single-Photon; Treatment Outcome

We present a case of subacute middle cerebral artery infarct, which demonstrates restricted diffusion on MRI and reperfusion hyperemia in the posterior half of the lesion on angiography. Tc-99m ethyl cysteinate dimer (ECD) SPECT obtained shortly after the MRI failed to demonstrate perfusion defects in the regions demonstrating reperfusion hyperemia on angiography, underestimating the true size of the infarct. Crossed cerebellar diaschisis is, however, present. SPECT studies obtained over the following weeks demonstrated gradual enlargement of the lesion to approximate the MRI signal changes over a 19-day period. The case presented demonstrates retention of ECD in the infarcted brain. Several studies have demonstrated that Tc-99m ECD uptake is dependent on preserved brain tissue function because tracer retention requires enzymatic esterase activity, rather than the passive, nonenergy dependent trapping of Tc-99m hexamethylpropyleneamine oxime. Hence, infarcted areas undergoing reperfusion hyperemia are unlikely to demonstrate ECD uptake. This report illustrates that MRI diffusion weighted imaging may be more accurate in demonstrating the full extent of reperfused infarcts earlier than Tc-99m ECD SPECT. SPECT in this case failed to demonstrate reduced uptake in reperfused regions of the infarct. Also, crossed cerebellar diaschisis may serve as an early marker of extensive neuronal dysfunction.

Topics: Adult; Brain Ischemia; Cysteine; Diagnostic Errors; Diffusion Magnetic Resonance Imaging; False Negative Reactions; Female; Humans; Hyperemia; Organotechnetium Compounds; Radiopharmaceuticals; Reperfusion Injury; Severity of Illness Index; Stroke; Tomography, Emission-Computed, Single-Photon