Improved Detection of Anterior Circulation Occlusions: The “Delayed Vessel Sign” on Multiphase CT Angiography

Fellows’ Journal Club

The authors evaluated 23 distal anterior circulation occlusions during a 2-year period. Ten M1-segment occlusions and 10 cases without a vessel occlusion were also included. There was significant improvement in the sensitivity of detection of distal anterior circulation vessel occlusions, overall confidence, and time taken to interpret with multiphase CTA compared with single-phase CTA. The delayed vessel sign is a reliable indicator of anterior circulation vessel occlusion, particularly in cases involving distal branches.

Abstract

Figure 1 from paper
Multiphase CTA and follow-up MR imaging of an 83-year-old woman presenting with acute right upper limb weakness and dysphasia. A, Axial MIP of the first phase demonstrates subtle paucity of vessels in the distribution of the left MCA compared with the right side. B, Axial MIP of the second phase demonstrates the delayed vessel sign (long arrow). There is delayed enhancement of the distal left MCA via pial collateral vessels (short arrows). This vessel is not seen on the first phase due to the presence of an M2 vessel occlusion. C, Axial MIP of the third phase also demonstrates the “delayed” left MCA vessel (long arrow). D, DWI b=1000 image 2 weeks postpresentation demonstrates a recent infarct (arrow) in the same left MCA territory.

BACKGROUND AND PURPOSE

Multiphase CTA, a technique to dynamically assess the vasculature in acute ischemic stroke, was primarily developed to evaluate collateral filling. We have observed that it is also useful in identifying distal anterior circulation occlusions due to delayed anterior circulation opacification on multiphase CTA, an observation we term the “delayed vessel sign.” We aimed to determine the usefulness of this sign by comparing multiphase CTA with single-phase CTA.

MATERIALS AND METHODS

All 23 distal anterior circulation occlusions during a 2-year period were included. Ten M1-segment occlusions and 10 cases without a vessel occlusion were also included. All patients had follow-up imaging confirming the diagnosis. Initially, the noncontrast CT and first phase of the multiphase CTA study for each patient were blindly evaluated (2 neuroradiologists, 2 radiology trainees) for an anterior circulation occlusion. Readers’ confidence, speed, and sensitivity of detection were recorded. Readers were then educated on the “delayed vessel sign,” and each multiphase CTA study was re-examined for a vessel occlusion after at least 14 days.

RESULTS

There was significant improvement in the sensitivity of detection of distal anterior circulation vessel occlusions (P < .001), overall confidence (P < .001), and time taken to interpret (P < .001) with multiphase CTA compared with single-phase CTA. Readers preferred MIP images compared with source images in >90% of cases.

CONCLUSIONS

The delayed vessel sign is a reliable indicator of anterior circulation vessel occlusion, particularly in cases involving distal branches. Assessment of the later phases of multiphase CTA for the delayed vessel sign leads to a significant improvement in the speed and confidence of interpretation, compared with single-phase CTA.

Read this article: http://bit.ly/2h5aqxw

Improved Detection of Anterior Circulation Occlusions: The “Delayed Vessel Sign” on Multiphase CT Angiography
Tags:         
jross
Jeffrey Ross • Mayo Clinic, Phoenix

Dr. Jeffrey S. Ross is a Professor of Radiology at the Mayo Clinic College of Medicine, and practices neuroradiology at the Mayo Clinic in Phoenix, Arizona. His publications include over 100 peer-reviewed articles, nearly 60 non-refereed articles, 33 book chapters, and 10 books. He was an AJNR Senior Editor from 2006-2015, is a member of the editorial board for 3 other journals, and a manuscript reviewer for 10 journals. He became Editor-in-Chief of the AJNR in July 2015. He received the Gold Medal Award from the ASSR in 2013.

Leave a Reply