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Correlation of cerebrovascular reserve assessed by acetazolamide-stress SPECT with collaterals on arterial spin-labeling MRI in patients with carotid occlusive disease1Department of Radiology, Seoul Veterans Hospital, Seoul, Korea, Republic of
Synopsis
We evaluated the correlation between cerebrovascular reserve (CVR) on acetazolamide-stress single photon emission computed tomography (SPECT) brain scans and collaterals on arterial spin-labeling (ASL) magnetic resonance imaging (MRI) in internal carotid artery (ICA) stenosis.With acetazolamide stress SPECT, the 21/74 (28%) patients showed evidence of decreased CVR. In 7/53 (13%) of the normal CVR group and 10/21 (48%) of the reduced CVR from the SPECT results, ASL showed ATA in ipsilateral to the stenosis. Significant relationship was observed between reduced CVR group and ATA showing group in ICA stenosis patients on ASL brain perfusion (p=0.004).
Purpose
We evaluated the correlation between cerebrovascular reserve (CVR) on acetazolamide-stress single photon emission computed tomography (SPECT) brain scans and collaterals on arterial spin-labeling (ASL) magnetic resonance imaging (MRI) in internal carotid artery (ICA) stenosis.Methods
74 patients with ICA stenosis (>70%) underwent pulsed ASL brain perfusion scan and SPECT brain perfusion scan in the resting and after acetazolamide challenge. We observed the presence of intracranial collaterals, which are manifested by arterial transit artifact (ATA), on ASL. CVR based on rest-SPECT and acetazolamide-stress SPECT was calculated. With acetazolamide stress SPECT, the 74 patients were grouped as either showing or not showing evidence of decreased CVR. We assessed the relationship between reduced CVR and intracranial collaterals shown as ATA on ASL.Results
In 17/74 (23%) of the ICA stenosis patients, ASL showed ATA in ipsilateral to the stenosis. With acetazolamide stress SPECT, the 21/74 (28%) patients showed evidence of decreased CVR. In 7/53 (13%) of the normal CVR group and 10/21 (48%) of the reduced CVR from the SPECT results, ASL showed ATA in ipsilateral to the stenosis. Significant relationship was observed between reduced CVR group and ATA showing group in ICA stenosis patients on ASL brain perfusion (p=0.004).Discussion
In response to a decrease in local perfusion pressure, there is recruitment of flow from both circle of Willis and leptomeningeal anastomoses, which compensate for the lack of anterograde flow. The eventual failure of collateral pathways is thought to lead to infarct growth and is ultimately responsible for the decreasing efficacy of stroke therapy with time. On ASL, late-arriving flow appears as serpiginous high ASL signal within cortical vessels, which has been termed ATA. ATA with ASL imaging is a region compatible with collateral flow, showing multiple serpiginous high signal intensity structures. ATA was seen frequently in a small group of acute ischemic stroke patients and was associated with tissue survival and improved clinical outcome. Also, patients with chronic hypoperfusion with ATA had good CVR in response to acetazolamide. In our study, statistically significant positive correlation was noted between normal CVR group and ICA stenosis patients with ATA. Patients who had decreased CVR on acetazolamide-challenged SPECT brain studies showed increased dependence on leptomeningeal collaterals.Conclusion
Our results suggest that ICA stenosis patients who had reduced CVR on brain SPECT showed increased dependence on intracranial collaterals shown as ATA on ASL brain scans.Acknowledgements
No acknowledgement found.References
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Figures
Figure 1. 72-year-old male, severe stenosis of the right proximal cervical ICA.
Multiple serpiginous high signal intensity (red) structures were seen in the right frontotemporal area on pulsed ASL with right proximal cervical ICA stenosis patient, and on acetazolamide stress SPECT image, there was reduced CVR change in the right frontotemporal area.
Figure 2. 79-year-old male, severe stenosis of the right proximal cervical ICA.
No ATA in the right frontotemporal area were seen on pulsed ASL with right proximal cervical ICA stenosis patient, and on acetazolamide stress SPECT image, there was no CVR change in the right frontotemporal area.
