Does Perfusion Computed Tomography Facilitate Clinical Decision Making for Thrombolysis in Unselected Acute Patients with Suspected Ischaemic Stroke?

Abstract

Background: Despite use in clinical practice and major positive trials of thrombolysis, non-contrast computed tomography (NCCT) is not sensitive for identifying penumbral tissue in acute stroke. This study evaluated how physiological imaging using CT perfusion (CTP) could add to the diagnostic utility of an NCCT and inform clinical decisions regarding thrombolysis. Methods: Forty imaging datasets containing NCCT and CTP were retrospectively identified from a cohort of consecutive acute stroke patients. Two sets of observers (n = 6) and a neuroradiologist evaluated the images without knowledge of clinical symptoms. Inter-observer agreement was calculated using the ĸ statistic for identifying acute ischaemic change on NCCT: perfusion abnormalities (namely cerebral blood volume, cerebral blood flow and time to peak), and penumbral tissue on perfusion maps obtained by two image processing algorithms. Results: Inter-rater agreement was moderate (ĸ = 0.54) for early ischaemic change on NCCT. Perfusion maps improved this to substantial for cerebral blood volume (ĸ = 0.67) and to almost perfect for time to peak (ĸ = 0.87) and cerebral blood flow (ĸ = 0.87). The agreement for qualitative assessment of penumbral tissue was substantial to perfect for images obtained using the two different perfusion algorithms. Overall, there was a high rate of decision to thrombolyse based on NCCT (81.25%). CTP strengthened the decision to thrombolyse based on NCCT in 38.3% of cases. It negatively influenced the decision in 14.6% of cases, this being significantly more common in experienced observers (p = 0.02). Conclusions: We demonstrate that the qualitative evaluation of CTP produces near perfect inter-observer agreement, regardless of the post-processing method used. CTP is a reliable, accessible and practical imaging modality that improves confidence in reaching the appropriate diagnosis. It is particularly useful for less experienced clinicians, to arrive at a physiologically informed treatment decision.

Stroke Mimics Treated with Thrombolysis: Further Evidence on Safety and Distinctive Clinical Features

“…In our experience, not only in the HaNDL case, but also in the migraine patient, this technique yielded conflicting results. Despite some studies claiming its utility to assess SM, for example in encephalitis [24], a word of caution should be given when interpreting the results of these perfusion studies, which may be helpful but also misleading in the acute stroke settings [25]. …”

Diagnostic Accuracy of CT Perfusion Imaging for Detecting Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

“…Furthermore, CTP can be used to determine the extent and potential reversibility of ischemia. This may be helpful in selecting patients who are likely to benefit from thrombolytic therapy [2,3,4,5,6]. …”

A novel clinical and imaging based score for predicting outcome prior to endovascular treatment of acute ischemic stroke

“…CT perfusion has demonstrated good inter-rater reliability in other investigations38 and is easy to interpret, making it ideal for many practitioners 31. In most clinical settings, candidacy for treatment is decided by the clinician quickly reviewing perfusion imaging to evaluate salvageable ischemic tissues.…”