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Published on: September 25, 2019
Recognizing false ischemic penumbras in CT brain perfusion studies
Alan C Best1, Natasha R Acosta, Jennifer E Fraser
1Department of Radiology, University of Colorado Health Sciences Center, 12401 E 17th Ave, Aurora, CO 80045, USA. Alan.best@UCDenver.edu
Summary
Computed tomography (CT) perfusion imaging helps identify ischemic penumbra for acute stroke treatment. Radiologists must correlate CT perfusion parameters with other imaging and clinical data to avoid misinterpreting benign conditions as penumbra, preventing treatment errors.
Area of Science:
- Radiology
- Neurology
- Medical Imaging
Background:
- Computed tomography (CT) is crucial for acute stroke diagnosis and treatment decisions.
- CT perfusion imaging provides key parameters like time to peak enhancement, mean transit time, and cerebral blood volume.
- Accurate differentiation between ischemic penumbra and infarcted tissue is vital due to the risks of thrombolytic therapy.
Purpose of the Study:
- To highlight the role of CT perfusion in acute stroke assessment.
- To discuss potential pitfalls in interpreting CT perfusion parameters, leading to false penumbra identification.
- To emphasize the importance of correlating CT perfusion findings with other diagnostic modalities.
Main Methods:
- Utilizing CT perfusion imaging with intravenous iodinated contrast material.
- Analyzing parameters such as time to peak enhancement, mean transit time, and cerebral blood volume.
- Correlating CT perfusion findings with unenhanced head CT, angiography, CT angiography, and diffusion-weighted MRI.
Main Results:
- A delay in peak enhancement or increased mean transit time with normal/slightly abnormal cerebral blood volume may suggest ischemic penumbra.
- Five potential causes of false penumbras were identified: upstream flow restriction, evolving ischemia, vascular dysregulation, patient positioning, and Circle of Willis variants.
- Each cause of false penumbra presents a distinct imaging pattern.
Conclusions:
- Accurate interpretation of CT perfusion requires awareness of conditions that mimic ischemic penumbra (benign oligemia).
- Correlation with clinical history and other imaging techniques is essential to avoid misdiagnosis.
- Familiarity with false penumbra patterns enhances diagnostic confidence and prevents treatment errors in acute stroke management.
