Simultaneous PET/MRI in stroke: a case series

Area of Science:

• Neurology
• Radiology
• Nuclear Medicine

Background:

• Systemic thrombolysis for stroke is time-sensitive, with a critical window often exceeding 4.5 hours post-onset.
• Previous prospective studies using MRI-guided thrombolysis beyond this window failed to meet primary endpoints.
• Limited accuracy of MRI in quantifying critical hypoperfusion was identified as a potential reason for these failures.

Observation:

• This study reports the first simultaneous use of [(15)O]H2O-positron emission tomography (PET) and MRI in stroke patients and an ovine model.
• Discrepancies were noted between the simultaneous PET and MRI measurements.
• These observed discrepancies may explain the current limitations of MRI in assessing stroke severity.

Findings:

• Simultaneous [(15)O]H2O-PET/MRI provides complementary information regarding cerebral blood flow and tissue perfusion.
• MRI underestimated the extent of critical hypoperfusion compared to PET in certain cases.
• PET/MRI demonstrated potential for more accurate assessment of ischemic penumbra.

Implications:

• [(15)O]H2O-PET/MRI may overcome the limitations of MRI alone in identifying critically hypoperfused brain tissue.
• This combined imaging approach could significantly improve patient stratification for thrombolysis therapy in stroke.
• Future clinical trials may benefit from incorporating advanced imaging techniques like PET/MRI for optimized treatment selection and improved outcomes.