SPOTRIAS Project 2
IMPACT -Infarct Modeling through Perfusion Assessment by CT
Overview
An ischemic stroke occurs when an artery in the brain is blocked by a blood clot. By the time the patient is evaluated, some of the tissue fed by the blocked vessel is dead, while other tissue is damaged but has the potential to recover if blood flow is restored. Medications which can restore the flow by dissolving the clot carry a risk of causing hemorrhage, and are currently used only in a very small percentage of stroke patients. In order to decide whether the risks involved in dissolving the clot are justified, a physician must be able to predict what tissue is irreversibly damaged, how much brain tissue could be saved by restoring flow, and what that would mean for the patient’s ability to function.
Purpose
The purpose of this work is to develop an accurate way to make this prediction using CT scanning, a technology that is widely available in hospitals throughout the country.
Enrollment
A total of 500 individuals with acute ischemic stroke will be enrolled at the Massachusetts General and Brigham and Women’s Hospitals in Boston.
Procedures
In patients who have suffered acute ischemic stroke, a CT scan evaluation of the blood flow to the brain (a study called “CT perfusion”) will be performed at the time of initial evaluation. Further imaging will be used to show where blood flow has been restored at 24 hours after the event, and to see where brain tissue eventually recovers and where it dies. These results will be compared to the patients’ long-term clinical status. This will help decide exactly how CT perfusion can best be used to evaluate the brain after a stroke, and turn CT perfusion into a more precise and useful decision-making tool for physicians who treat stroke patients.
Example
These are images from a CT perfusion study. There is an area of decreased cerebral blood volume (yellow arrow), which represents tissue that is irreversibly damaged. There is a larger area of decreased cerebral blood flow and increased mean transit time (green arrows), which represents tissue that is oxygen deficient, but not yet irreversibly damaged. The mismatch between these areas represents tissue which may be saved by re-establishing flow through the blocked vessel, and is thus a potential target for therapy.
Inclusion & Exclusion Criteria
Inclusion Criteria
- Age > 18 years
- Acute symptomatic supratentorial infarct
- CTP performed at admission (within 9 hours of symptom onset)
Exclusion Criteria
- Creatinine > 1.5
- Pre-existing chronic renal disease
- History of allergic reaction or other contraindication to contrast dye
- Clinical signs of congestive heart failure on examination or CXR
- Positive pregnancy test (pre-menopausal women only)
- Unstable angina, enzyme or EKG evidence of cardiac ischemia*
- Subject has proven alternate etiology for stroke-like symptom (e.g. ICH, SAH, subdural hematoma, meningitis, seizure, multiple sclerosis, tumor)
- Acute symptomatic infratentorial ischemia
* applies only to those patients who would receive a CTA/CTP for study-specific research purposes
References
Shetty SK. Lev MH. CT perfusion in acute stroke. [Review] [135 refs] Neuroimaging Clinics of North America. 15(3):481-501, ix, 2005 Aug.
PMID: 16360585 [PubMed - indexed for MEDLINE]
Wintermark M. Flanders AE. Velthuis B. Meuli R. van Leeuwen M. Goldsher D. Pineda C. Serena J. van der Schaaf I. Waaijer A. Anderson J. Nesbit G. Gabriely I. Medina V. Quiles A. Pohlman S. Quist M. Schnyder P. Bogousslavsky J. Dillon WP. Pedraza S. Perfusion-CT assessment of infarct core and penumbra: receiver operating characteristic curve analysis in 130 patients suspected of acute hemispheric stroke. Stroke. 37(4):979-85, 2006 Apr.
PMID: 16514093 [PubMed - indexed for MEDLINE]
Schaefer PW. Roccatagliata L. Ledezma C. Hoh B. Schwamm LH. Koroshetz W. Gonzalez RG. Lev MH. First-pass quantitative CT perfusion identifies thresholds for salvageable penumbra in acute stroke patients treated with intra-arterial therapy. American Journal of Neuroradiology. 27(1):20-5, 2006 Jan.
PMID: 16418350 [PubMed - indexed for MEDLINE]