FIG 3. Example of a false-positive result. The same color scale is used to display quantitative rCBF images calculated by using the IMP autoradiographic method at resting state and with the acetazolamide challenge. This patient had a symptomatic occluded ICA on the right side. After the administration of acetazolamide, the patient’s rCBF in the MCA territory increased by 10.3 mL/100 g/min on the right side and by 26.4 mL/100 g/min on the contralateral side. This increase was asymmetrical, with the qualitative assessment defining rCVR as reduced (AI_Hem change = -28.3), although %_Hem on the occluded side, as determined quantitatively, showed a normal flow response of 31.0%.