Optimal Brain 99mTc-Ethyl Cysteinate Dimer SPECT Imaging and Analysis to Detect Misery Perfusion on 15O PET Imaging in Patients With Chronic Occlusive Disease of Unilateral Major Cerebral Artery

Purpose: Misery perfusion is defined as marginally sufficient cerebral blood supply relative to cerebral metabolic demand. The aim of the present study was to determine the optimal brain Tc-99m-ethyl cysteinate dimer (ECD) SPECT imaging and analysis to detect misery perfusion on O-15 PET imaging in patients with chronic occlusive disease of unilateral internal carotid or middle cerebral artery (MCA). Methods: For 97 patients, cerebral blood flow, cerebral metabolic rate of oxygen, and oxygen extraction fraction were measured using O-15 PET; Tc-99m-ECD SPECT was performed using dynamic scanning with a scan duration of 10 minutes each for 50 minutes after tracer administration. A region of interest was placed in the bilateral MCA territories and in the bilateral cerebellar hemispheres in all standardized images using a 3-dimensional stereotaxic region-of-interest template and affected-to-contralateral asymmetry ratio in the MCA territory (AR(MCA)) and contralateral-to-affected asymmetry ratio in the cerebellar hemisphere (AR(cbl)) were calculated. Results: The AR(MCA) or AR(cbl) on Tc-99m-ECD SPECT with a scan time of 20 to 30 minutes after tracer administration (AR(MCA20-30) or AR(cbl20-30)) was correlated with AR(MCA) on PET cerebral blood flow (r = 0.654) or AR(MCA) on PET cerebral metabolic rate of oxygen (r = 0.576), respectively, more strongly than with other scan times. The area under the receiver operating characteristic curve for detecting abnormally elevated AR(MCA) on PET oxygen extraction fraction was significantly greater for AR(cbl20-30)/AR(MCA20-30) (0.947) than for AR(MCA20-30) alone (0.780) (difference between areas, 0.167; P = 0.0001) on Tc-99m-ECD SPECT. Conclusions: Combination of asymmetries in the cerebellar and cerebral hemispheres on Tc-99m-ECD SPECT in a scan time of 20 to 30 minutes after tracer administration optimally detects misery perfusion in unilateral internal carotid artery or MCA occlusive disease.