Recent Administration of Iodinated Contrast Renders Core Infarct Estimation Inaccurate Using RAPID Software

Scatterplot of CTP-measured core infarct volume versus postoperative core infarct volume as measured by MR imaging or CT for the recent IV contrast group (red) and the contrast-naïve group (blue) with lines of best fit. For the same preoperative CTP-measured core, the postoperative core infarct is greater in the recent IV contrast group, suggesting that recent IV contrast underestimates CTP-measured core infarct volume at presentation.

A 56-year-old man who presented to an outside hospital with a right MCA syndrome and ELVO confirmed on CTA. Last known well was approximately 11 hours before imaging at our institution. A, NCCT demonstrates loss of gray-white matter differentiation, in keeping with acute infarct, involving the right insula as well as the frontal and temporal opercula. B, CTA confirms a right M1 segment (yellow circle) occlusion. C, DWI reveals an extensive area of acute infarct correlating with the areas of hypoattenuation on the NCCT. TICI 3 reperfusion was achieved within 60 minutes of the CTP study, and the MR imaging was obtained later in the day.

CTP with RAPID postprocessing from the same patient as in Fig 3 suggests no core infarct (lack of pink color-coding and an rCBF of <30% volume of 0 mL) with a large area of ischemic penumbra (green color-coding with time-to-maximum [Tmax] of >6 seconds of 129 mL).

A 67-year-old man who presented directly to our institution (no recent IV contrast) with a left MCA syndrome and last known well approximately 8 hours before imaging. A and B, NCCT demonstrates hypoattenuation involving a large volume of the left MCA and anterior cerebral artery territories. C, CTA demonstrates a internal carotid terminus occlusion with involvement of the carotid terminus and A1 and M1 segments.

CTP imaging with RAPID postprocessing from the same patient as in Fig 5 suggests an extensive area of core infarct (pink color-coding and an rCBF of <30% volume of 234 mL) corresponding to the large volume of hypoattenuation on NCCT. Tmax indicates time-to-maximum.