Challenges and Adjunctive Use of CT Perfusion (CTP) in Acute Stroke: Pitfalls, False Negatives, and Diagnostic Clues for Stroke Mimics.

PURPOSE OF REVIEW: Computed tomography perfusion (CTP) has become an important tool for tissue-based assessment in acute ischemic stroke, particularly in patients considered for reperfusion therapy beyond conventional time windows. This review summarizes common pitfalls, diagnostic blind spots, and adjunctive uses of CTP. RECENT FINDINGS: Although CTP supports patient selection for endovascular thrombectomy in the extended window, automated core-penumbra estimates are vulnerable to technical and interpretive error. Major pitfalls include overestimation of ischemic core (ghost infarct core) and underestimation of core (perfusion scotoma). Negative automated maps do not exclude small deep infarcts or posterior circulation stroke, and perfusion abnormalities may also occur in stroke mimics. CTP should not be interpreted in isolation. Its greatest clinical value lies in integration with non-contrast CT, CT angiography, perfusion parameter maps, and clinical assessment.