The accuracy of ischemic core perfusion thresholds varies according to time to recanalization in stroke patients treated with mechanical thrombectomy: A comprehensive whole-brain computed tomography perfusion study

Abstract

Computed tomography perfusion (CTP) allows the estimation of pretreatment ischemic core after acute ischemic stroke. However, CTP-derived ischemic core may overestimate final infarct volume. We aimed to evaluate the accuracy of CTP-derived ischemic core for the prediction of final infarct volume according to time from stroke onset to recanalization in 104 patients achieving complete recanalization after mechanical thrombectomy who had a pretreatment CTP and a 24-h follow-up MRI-DWI. A range of CTP thresholds was explored in perfusion maps at constant increments for ischemic core calculation. Time to recanalization modified significantly the association between ischemic core and DWI lesion in a non-linear fashion ( p-interaction = 0.018). Patients with recanalization before 4.5 h had significantly lower intraclass correlation coefficient (ICC) values between CTP-predicted ischemic core and DWI lesion ( n = 54; best threshold relative cerebral blood flow (rCBF) < 25%, ICC = 0.673, 95% CI = 0.495–0.797) than those with later recanalization ( n = 50; best threshold rCBF < 30%, ICC = 0.887, 95% CI = 0.811–0.935, p = 0.013), as well as poorer spatial lesion agreement. The significance of the associations between CTP-derived ischemic core and clinical outcome at 90 days was lost in patients recanalized before 4.5 h. CTP-derived ischemic core must be interpreted with caution given its dependency on time to recanalization, primarily in patients with higher chances of early recanalization.

The ischemic penumbra: From concept to reality

“…92 A DT of > 2 s was also shown to accurately represent the penumbra, and when associated with CBF < 40% was shown to represent the core, but subsequently DT > 3 s and core < 30% has been shown to be more specific (Figure 2(c)). 8,9 A caveat is the time-dependence of the core threshold, which was well known from animal studies 7 but has been documented in man only recently, 10,11,93,94 pointing to the need to adjust the core threshold to time elapsed since stroke onset if a more accurate picture of the physiological situation is desired. To objectively select patients who can benefit from thrombolysis and fasten the process, automated measurement of MTT, Tmax, and CBF were developed, through a mathematical processing called deconvolution, with several variations.…”

Deep learning-based identification of acute ischemic core and deficit from non-contrast CT and CTA

“…8 Some studies have investigated the variations of CTP threshold selection according to the time to recanalization in stroke patients. [9][10][11] The parameter maps calculated from computed tomographic perfusion (CTP) images can be used to segment the ischemic core and deficit regions. According to the RAPID (iSchemaView, Stanford, CA) definition, a reduction in cerebral blood flow (CBF) to below 30% of normal brain tissue is associated with ischemic core, 12,13 while the prolonged time-to-maximum (Tmax) of the tissue residue function to more than 6 s is associated with deficit area.…”

Ensemble learning accurately predicts the potential benefits of thrombolytic therapy in acute ischemic stroke

“…Stroke is one of the leading causes of death worldwide, and almost half of stroke deaths result from ischemic stroke (1). Thrombolytic therapy, a procedure used for ischemic stroke, aims to recanalize the occluded vessel and reperfuse the ischemic tissue (2). However, as noted by Dr. Lyden, the decision to use thrombolytic therapy is "among the most difficult treatment decisions in medicine, given the risks involved and the compressed time frame available" (3).…”

“…Calculate the MDI for all features by Eq. [2], and then sort the results from large to small. The first K features are taken as the most important K features of the model.…”