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Published on: July 21, 2013
Derivation of power M-mode transcranial Doppler criteria for angiographic proven MCA occlusion
Maher Saqqur1, Michael D Hill, Andrei V Alexandrov
1Department of Medicine, University of Alberta, Alberta, Canada.
Insights
New criteria combining flow velocity ratios and M-mode signatures improve diagnosis of middle cerebral artery (MCA) occlusion in acute stroke patients. These findings enhance transcranial Doppler (TCD) reliability for bedside stroke assessment.
Area of Science:
- Neurology
- Medical Imaging
- Vascular Medicine
Background:
- Accurate diagnosis of cerebral artery occlusion is critical in acute stroke management.
- Current transcranial Doppler (TCD) criteria for diagnosing occlusion require refinement for improved bedside reliability.
Purpose of the Study:
- To develop stringent TCD criteria for diagnosing proximal middle cerebral artery (MCA) occlusion in patients with acute cerebral ischemia.
- To evaluate the diagnostic performance of mean flow velocity (MFV) ratios and power M-mode Doppler (PMD) resistance signatures.
Main Methods:
- TCD examinations were performed on 120 patients with acute cerebral ischemia undergoing digital subtraction angiography (DSA).
- MFV, pulsatility indices, and PMD resistance signatures were recorded in cerebral arteries.
- Receiver-operating characteristic (ROC) analysis was used to evaluate PMD-TCD findings against DSA-proven MCA occlusion.
Main Results:
- A low aMCA/iPCA MFV ratio (threshold 0.5) was strongly predictive of MCA occlusion (RR 2.31).
- High resistance or absent M-mode flow signatures in the proximal MCA were observed in 87% of M1 and M2 occlusions.
- Combining a low aMCA/iPCA MFV ratio with a low-resistance PMD signature increased the probability of occlusion to 87%.
Conclusions:
- Reliable criteria for proximal MCA occlusion in acute cerebral ischemia have been established using a combination of MFV ratios and M-mode flow resistance signatures.
- Further validation through multicenter studies is necessary to confirm these diagnostic criteria.
Background:
Stringent transcranial Doppler (TCD) criteria for diagnosing occlusion are needed for more reliable TCD performance at bedside in the acute stroke setting.
Subjects And Methods:
At three academic stroke centers, we performed TCD examination for patients with symptoms of cerebral ischemia who underwent digital subtraction angiography (DSA). We used a standard insonation protocol with power M-mode Doppler (PMD) TCD (TCD 100 M, Spencer Technologies Inc., Seattle, WA). We collected mean flow velocity (MFV), pulsatility indices (PI), and power M-mode resistance signature (absent, high, or low) in symptomatic middle (MCA), anterior (ACA), posterior (PCA), and in affected (a), ipsilateral (i), and contralateral (c-lat) cerebral arteries. Ratios of aMCA/c-lat MCA, aMCA/iACA, and aMCA/iPCA MFV were subsequently calculated. PMD-TCD flow findings were evaluated with a receiver-operating characteristic (ROC) analysis for angiographically proven MCA occlusion.
Results:
We studied 120 patients with acute cerebral ischemia with PMD-TCD examinations prior to or immediately after DSA. Lower aMCA velocities pointed to higher probability of occlusion (P= .055). The aMCA/iPCA MFV ratio was superior to the aMCA/iACA ratio and strongly predictive of occlusion at a threshold ratio of 0.5 (RR 2.31 CI(95) 2.13-2.51). High resistance or absent M-mode flow signatures in the proximal MCA were present in 87% of M1 and M2 MCA occlusions (probability 87%). In the presence of a low-resistance PMD signature, obtaining the aMCA/iPCA MFV ratio <0.5 increases probability of occlusion to 87%. Normal MFV ratios and low-resistance M-mode signatures are highly predictive of a negative angiogram for MCA occlusion.
Conclusion:
In acute cerebral ischemia, reliable criteria for proximal MCA occlusion have been developed based on combination of MFV ratios and M-mode flow resistance signatures. Validation of these criteria will require multicenter studies.
