Table 2 -.

Recommendations for refinement of ischemic core estimation and optimizing imaging acquisition and processing

Diffusion MRI	CT perfusion	Non-contrast CT
• Understanding temporary lesion reversal – is this an opportunity for cerebroprotection to prevent secondary injury?	Re-calibration against a refined diffusion MRI definition of core (requires contemporaneous CTP and MRI which has practical challenges) versus follow-up infarct volume in patients with rapid and complete reperfusion	Improved detection of subtle Hounsfield unit changes • High quality image acquisition • Judicious use of iterative reconstruction • Further exploration of dual energy acquisitions • Artificial Intelligence detection of subtle changes
Recognition of gradient of tissue injury (non-dichotomous tissue fate)	Maps with probabilistic information indicating the degree of confidence in tissue status may aid interpretation Artificial intelligence with multiparametric input +/− clinical variables is likely to outperform single parameter thresholds	Standardization of assessment of hemorrhagic transformation across CT and MRI modalities
Technical pitfalls to consider in analysis of apparent diffusion lesion reversal: • Initial infarct edema followed by atrophy • Co-registration inaccuracy • White versus grey matter differences	Technical pitfalls to consider in analysis of apparent CTP core salvage:  • temporary diffusion lesion reversal if follow-up imaging reference is DWI obtained <24h  • relative insensitivity of non-contrast CT to infarction if used as follow-up reference  • Co-registration inaccuracy  • White versus grey matter differences