Presentation
Transient (30 minute) left hemiparesis for investigation. No residual deficit.
Patient Data
Generalized reduction in signal intensity within the right ICA and intra-cranial branches as compared with the left ICA and basilar artery. Further assymetrical luminal narrowing in the distal right ICA below the skull base.
Luminal narrowing of the right ICA origin on B mode with high velocities and spectral broadening consistent with turbulent flow and more normal velocities and spectra distally.
Case Discussion
Time of flight MRA relies on unsaturated protons entering the scan plane to produce signal. If inflow is reduced substantially by a proximal stenosis them the protons within the scan plane are not rapidly refreshed thus saturated reducing the signal intensity. This is therefore a good sign of significant proximal stenosis even though the actual stenosis may not be seen.