Real-time Validation of Transcranial Doppler Criteria in Assessing Recanalization
Diogo C. Haussen, MD
Tsivgoulis et al. validated the utilization of transcranial Doppler (TCD) for the assessment of recanalization of large vessel acute ischemic strokes. This was achieved by comparing TCD to digital substraction angiography (DSA) during endovascular revascularization procedures. The authors evaluated time-linked DSA-TCD images from 96 angiographic runs during intra-arterial reperfusion procedures in 62 consecutive acute stroke patients.
Ultrasonographic recanalization (according to the Thrombolysis in Brain Ischemia – TIBI transcranial Doppler flow scale) was directly compared to angiographic recanalization (according to the thrombolysis in myocardial ischemia – TIMI score). The study’s main finding is that TCD could accurately predict reperfusion. The inter-rater reliability for evaluation of TIBI grades in the study was excellent. TCD had a sensitivity of 88%, specificity of 89%, and overall accuracy of 89% compared to DSA for the diagnosis of complete recanalization. When considering partial recanalization, the numbers were even more impressive. Moreover, the study found that complete recanalization by TCD was independently correlated with higher likelihood of good functional outcome at three months. The authors, however, do not provide a multivariate analysis for partial recanalization.
In the report, TCD was used by identifying the worst detectable residual flow-signals at a constant angle with transtemporal insonation. It is interesting that the authors were able to manage the difficult task of performing continuous TCD monitoring in agitated and uncooperative patients with large vessel occlusion.
In summary, the study comes timely considering that scarce data is available regarding the accuracy of TCD for detecting recanalization compared to DSA – or even MRA or CTA. It is a very well designed and executed study that encompassed a large sample size and included patients with occlusion in diverse intracranial locations (hence, enhancing its validity). It defines the precision of TCD in determining the arterial status during large vessel occlusion strokes, and promotes the utilization of this valuable – and possibly underutilized – tool.