Thrombus Permeability Is Associated With Improved Functional Outcome and Recanalization in Patients With Ischemic Stroke
Authors: Santos Emilie M.M. , Marquering Henk A. , den Blanken Mark D. , Berkhemer Olvert A. , Boers Anna M.M. , Yoo Albert J. , Beenen Ludo F. , Treurniet Kilian M. , Wismans Carrie , van Noort Kim , Lingsma Hester F. , Dippel Diederik W.J. , van der Lugt Aad , van Zwam Wim H. , Roos Yvo B.W.E.M. , van Oostenbrugge Robert J. , Niessen Wiro J. , Majoie Charles B. , Fransen Puck S.S. , Beumer Debbie , van den Berg Lucie A. , Schonewille Wouter J. , Vos Jan Albert , Nederkoorn Paul J. , Wermer Marieke J.H. , van Walderveen Marianne A.A. , Staals Julie , Hofmeijer Jeannette , van Oostayen Jacques A. , Lycklama à Nijeholt Geert J. , Boiten Jelis , Brouwer Patrick A. , Emmer Bart J. , de Bruijn Sebastiaan F. , van Dijk Lukas C. , Kappelle L. Jaap , Lo Rob H. , van Dijk Ewoud J. , de Vries Joost , de Kort Paul L.M. , van den Berg Jan S.P. , van Hasselt Boudewijn A.A.M. , Aerden Leo A.M. , Dallinga René J. , Visser Marieke C. , Bot Joseph C.J. , Vroomen Patrick C. , Eshghi Omid , Schreuder Tobien H.C.M.L. , Heijboer Roel J.J. , Keizer Koos , Tielbeek Alexander V. , den Hertog Heleen M. , Gerrits Dick G. , van den Berg-Vos Renske M. , Karas Giorgos B. , Sprengers Marieke E.S. , Jenniskens Sjoerd F.M. , van den Berg René , Koudstaal Peter J. , Boiten Jelis , van Dijk Ewoud J. , Wermer Marieke J.H. , Flach H. Zwenneke , Steyerberg Ewout W. , Brown Martin M. , Liebig Thomas , Stijnen Theo , Andersson Tommy , Mattle Heinrich P. , Wahlgren Nils , Koudstaal Peter J. , van der Heijden Esther , Ghannouti Naziha , Fleitour Nadine , Hooijenga Imke , Lindl-Velema Annemieke , Puppels Corina , Pellikaan Wilma , Janssen Kirsten , Aaldering Nicole , Elfrink Marjan , de Meris Joke , Geerlings Annet , van Vemde Gina , de Ridder Ans , Greebe Paut , de Bont-Stikkelbroeck José , Struijk Willy , Simons Tiny , Messchendorp Gert , van der Minne Friedus , Bongenaar Hester , Bodde Karin , Licher Silvan , Boodt Nikki , Ros Adriaan , Venema Esmee , Slokkers Ilse , Ganpat Raymie-Jayce , Mulder Maxim , Saiedie Nawid , Heshmatollah Alis , Schipperen Stefanie , Vinken Stefan , van Boxtel Tiemen , Koets Jeroen , Boers Merel , Borst Jordi , Jansen Ivo , Kappelhof Manon , Lucas Marit , Geuskens Ralph , Barros Renan Sales , Dobbe Roeland , Csizmadia Marloes 
Published: February 2016

Background and Purpose—
Preclinical studies showed that thrombi can be permeable and may, therefore, allow for residual blood flow in occluded arteries of patients having acute ischemic stroke. This perviousness may increase tissue oxygenation, improve thrombus dissolution, and augment intra-arterial treatment success. We hypothesize that the combination of computed tomographic angiography and noncontrast computed tomography imaging allows measurement of contrast agent penetrating a permeable thrombus, and it is associated with improved outcome.

Methods—
Thrombus and contralateral artery attenuations in noncontrast computed tomography and computed tomographic angiography images were measured in 184 Multicenter Randomized Clinical trial of Endovascular treatment of acute ischemic stroke in the Netherlands (MR CLEAN) patients with thin-slice images. Two quantitative estimators of the thrombus permeability were introduced: computed tomographic angiography attenuation increase (Δ) and thrombus void fraction (ε). Patients were dichotomized as having a pervious or impervious thrombus and associated with outcome, recanalization, and final infarct volume.

Results—
Patients with Δ≥10.9 HU (n=81 [44%]) and ε≥6.5% (n=77 [42%]) were classified as having a pervious thrombus. These patients were 3.2 (95% confidence interval, 1.7–6.4) times more likely to have a favorable outcome, and 2.5 (95% confidence interval, 1.3–4.8) times more likely to recanalyze, for Δ based classification, and similarly for ε. These odds ratios were independent from intravenous or intra-arterial treatment. Final infarct volume was negatively correlated with both perviousness estimates (correlation coefficient, −0.39 for Δ and −0.40 for ε).

Conclusions—
This study shows that simultaneous measurement of thrombus attenuation in noncontrast computed tomography and computed tomographic angiography allows for quantification of thrombus perviousness. Thrombus perviousness is strongly associated with improved functional outcome, smaller final infarct volume, and higher recanalization rate.