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AJNR - American Journal of Neuroradiology

Published ahead of print on July 18, 2008
doi: 10.3174/ajnr.A1080

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American Journal of Neuroradiology 29:e65, September 2008
© 2008 American Society of Neuroradiology

Letter

Intracranial Stent Restenosis Diagnosed on Routine Duplex Follow-Up Investigation

K. Gröschel^a, S. Schnaudigel^a, J.H. Buhk^a, M. Knauth^a and A. Kastrup^a

^a University of Göttingen
Göttingen, Germany

We read with great interest the article of Turk et al,¹ in which the authors describe their experience with restenoses after intracranial stent placement. In this article, most of the restenoses were diagnosed by means of conventional intra-arterial digital subtraction angiography (DSA) on routine follow-up investigations. Although DSA is currently the gold standard for detecting intracranial adjacent or in-stent restenosis (ISR), we would like to point out that less-invasive techniques for follow-up investigations should be considered, especially in patients with an increased risk for ISR, such as young and female patients.¹ With respect to these techniques, we would like to report the following case.

A 48-year-old currently asymptomatic woman was seen in our institutional neurovascular clinic for a routine duplex follow-up investigation. Three months before presentation, a symptomatic intracranial stenosis of the right middle cerebral artery had been treated with an intracranial stent. The indication for the stent placement had been recurrent symptoms despite dual antiplatelet therapy (aspirin and clopidogrel).

Transcranial duplex sonography revealed a blunted Doppler signal intensity with flattened systolic flow acceleration at the distal end of the stent (Fig 1A). CT angiography (Fig 1B) corroborated this finding showing a compromised arterial filling distal to the stent but failed to depict the stent lumen. Subsequent DSA (Fig 1C) documented bilateral stenoses on both sides of the stent.

View larger version (60K): [in this window] [in a new window]   Fig 1. A, Transcranial duplex sonography of the right middle cerebral artery showing compromised flow velocities distal to stent in a depth of 48 mm. B, CT angiography demonstrates a reduced filling at the distal part of the stent. C, Finally, intra-arterial digital subtraction angiography reveals bilateral restenoses on both sides of the stent (black arrows).

This case illustrates that ISR can be assessed noninvasively with transcranial duplex sonography. A typical finding of an intracranial stenosis on transcranial Doppler sonography is mean flow velocity flow acceleration >100 cm/s.² However, within high-grade or tandem stenoses, as in our patient, reduced blood flow velocities can be found. These can then be graded according to the thrombolysis in myocardial ischemia flow grades.³

Patients with intracranial stents require close follow-up. If the anatomy of the temporal bone window allows sufficient transcranial insonation, noninvasive Doppler or duplex sonography should be considered as the primary technique to screen for ISR. However, in some cases, there will still be a need to confirm abnormal findings with additional imaging techniques. Whether traditional CT angiography, MR angiography, or flat-panel-detector angiographic CT⁴ is sufficient in this scenario is still under debate.

References

1. Turk AS, Levy EI, Albuquerque FC, et al. Influence of patient age and stenosis location on Wingspan in-stent restenosis. AJNR Am J Neuroradiol 2008;29:23–27. Epub 2007 Nov 7[Abstract/Free Full Text]

2. Feldmann E, Wilterdink JL, Kosinski A, et al. The Stroke Outcomes and Neuroimaging of Intracranial Atherosclerosis (SONIA) trial. Neurology 2007;68:2099–106[Abstract/Free Full Text]

3. Demchuk AM, Burgin WS, Christou I, et al. Thrombolysis in brain ischemia (TIBI) transcranial Doppler flow grades predict clinical severity, early recovery, and mortality in patients treated with intravenous tissue plasminogen activator. Stroke 2001;32:89–93[Abstract/Free Full Text]

4. Benndorf G, Strother CM, Claus B, et al. Angiographic CT in cerebrovascular stenting. AJNR Am J Neuroradiol 2005;26:1813–18[Abstract/Free Full Text]

This Article Figures Only Full Text (PDF) All Versions of this Article: ajnr.A1080v1 ajnr.A1080v2 29/8/e65    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Gröschel, K. Articles by Kastrup, A. Search for Related Content PubMed PubMed Citation Articles by Gröschel, K. Articles by Kastrup, A.