Visual rating of TTP/ASL.

Results of the visual qualitative analysis. As hypoperfusion in ASL occurred exclusively as part of ATDA and not isolated, for ASL only the categories ATDA and normal are presented.
Rows show imaging findings for ASL-CBF, columns show imaging findings for DSC-TTP. Patients rated uninterpretable were excluded. Of 14 patients with a TTP delay, 10 showed Arterial Transit Delay Artifacts in ASL (specificity: 71%; false negative rate: 29%). Out of 3 patients with normal findings in TTP, 1 showed ATDAs in ASL (false positive rate: 67%).
DSC-TTP: Dynamic Susceptibility Contrast - Time to Peak; ASL: Arterial Spin Labeling; ATDA: Arterial Transit Delay Artifact.