Figure 6. Data showing the potential utility of multi-modal quantitative functional neuroimaging for detecting altered hemodynamic relationships following stroke.

(A) Activation maps in response to a unilateral joystick task for controls (n=11) and chronic stroke patients (n=11) following middle cerebral artery (MCA) territory ischemic stroke. In controls, activation is largest in the hemisphere contralateral (cont) to the moved hand; in patients movement always occurred with the paretic hand, yet activation is less well localized to primary motor cortex, consistent with remapping of motor function to new cortical regions. A block-averaged time course for (B) a control subject and (C–D) two different chronic MCA-territory stroke patients. Gray areas depict the stimulus period. For the control, a robust BOLD change (P<0.05) is observed with normal cerebral blood flow-weighted (CBFw) (P<0.05) and cerebral blood volume-weighted (CBVw) (P<0.05) reactivity. Alternatively, despite similar stroke types (right MCA territory; residual bilateral steno-occlusion), Patient A (Fugl-Meyer=37) is less-impaired than Patient B (Fugl-Meyer=51). In Patient A, CBF reactivity is maintained throughout motor cortex (red curve) by large autoregulatory increases in CBV (green curve), but negligible CBF reactivity is observed in Patient B. The BOLD response, which is negative or negligible in both patients, cannot explain the differences in motor function. Data demonstrate how multi-modal imaging can be used to explain differences in motor impairment for similar stroke extensions. Additional information in a larger patient cohort can be found in (Blicher et al., 2012).