{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,7,30]],"date-time":"2025-07-30T12:35:22Z","timestamp":1753878922990,"version":"3.41.2"},"reference-count":22,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2025,6,7]],"date-time":"2025-06-07T00:00:00Z","timestamp":1749254400000},"content-version":"vor","delay-in-days":37,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Journal of Neuroimaging"],"published-print":{"date-parts":[[2025,5]]},"abstract":"<jats:title>ABSTRACT<\/jats:title><jats:sec><jats:title>Background and Purpose<\/jats:title><jats:p>M2 middle cerebral arterial (MCA) occlusions present a greater radiological challenge when compared to more proximal occlusions and additional signs aiding detection could be helpful. We routinely image patients with a dual\u2010phase CT angiography (CTA) protocol, encompassing a bolus\u2010tracked arterial\/early and then delayed\u2010phase (40\u2010s post contrast injection) acquisition. We screened a 12\u2010month period of our local thrombectomy database as a preliminary investigation into additional signs that can be gleaned to aid M2 occlusion diagnosis when imaged using this technique.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>We reviewed the CTA and digital subtraction angiographic (DSA) imaging in 10 consecutive patients with M2 MCA occlusions who subsequently underwent thrombectomy.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>All patients showed the presence of hyperattenuating M3 and M4 vessels distal to the occlusion on delayed\u2010phase but not early\u2010phase CTA (despite venous opacification evident on the latter). Compared to the contralateral side, attenuation values were significantly elevated in these vessels (202.3 [23.9] vs. 108.5 [16.4] Hounsfield units [HU]; 95% confidence interval [CI] of difference: 69.7\u2013117.9, <jats:italic>p<\/jats:italic>\u00a0&lt;\u00a00.0001). Eight of 10 patients also showed associated ipsilateral hyperattenuating cortical veins; the attenuation difference compared to contralateral cortical veins was 263.5 (58.3) vs. 151 (16.7) HU, 95% CI: 69.0\u2013156.0, <jats:italic>p<\/jats:italic> = 0.0005. Collateral appearance and washout were much brisker on DSA suggesting that the signs on delayed\u2010phase CTA represent the retrograde accumulation of contrast material distal to the occlusion after multiple contrast passes with slowed resultant venous flow accounting for an accumulation on the venous side.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>An additional phase at 40\u2010s displays hyperattenuating distal arteries and cortical veins that could aid in occlusion detection.<\/jats:p><\/jats:sec>","DOI":"10.1111\/jon.70060","type":"journal-article","created":{"date-parts":[[2025,6,8]],"date-time":"2025-06-08T05:33:28Z","timestamp":1749360808000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Hyperattenuating Collateral Arteries and Accompanying Cortical Veins as Auxiliary Signs of M2 Occlusion on Dual\u2010Phase CTA"],"prefix":"10.1111","volume":"35","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7744-2833","authenticated-orcid":false,"given":"Alex","family":"Mortimer","sequence":"first","affiliation":[{"name":"Department on Interventional Neuroradiology North Bristol NHS Trust  Bristol UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Richard","family":"Flood","sequence":"additional","affiliation":[{"name":"Department on Interventional Neuroradiology North Bristol NHS Trust  Bristol UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sophie","family":"Dunkerton","sequence":"additional","affiliation":[{"name":"Department on Interventional Neuroradiology North Bristol NHS Trust  Bristol 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