Dynamic Susceptibility Contrast MRI Perfusion
by Dr. Jeffrey M. Pollock, MD
How it works: Dynamic Susceptibility Contrast or DSC is a method of measuring cerebral blood flow, or blood flow to the brain. The technique requires intravenous contrast delivered through an automated power injector attached to an IV. The scanner creates an image showing multiple cerebral perfusion parameters including cerebral blood flow, mean time to enhance, and negative enhancement integral or cerebral blood volume. These techniques are most beneficial to patients with vascular stenosis, stroke, and brain tumors.
Equipment: Our MRI suite uses the latest Phillips 3.0 tesla magnets coupled with a state of the art Phillips Clinical Cerebral perfusion software package. Processing is performed by the technologist as soon as the scan is completed and images are available for immediate interpretation.
Benefits: DSC perfusion gives the most thorough evaluation of cerebral blood flow. In addition to flow, the technique gives other parameters such as blood volume and transit time that allow the neuroradiologist to more accurately depict the true state of the brain perfusion. These additional parameters have been thoroughly studied with regard to stroke and tumor evaluation (http://radiology.rsna.org/content/247/2/490.long).
Stroke and TIA: The perfusion parameters can show brain tissue at risk of stroke before the stroke has occurred. The best example of this is a patient with a transient ischemic attack or TIA . These patient's have brief stroke like symptoms and but may have a normal MRI. DSC perfusion can reveal subtle perfusion changes that could allow possible therapeutic interventions to prevent a future stroke.
Tumors: Cerebral blood volume correlates with the tumor grade or how malignant the tumor is. Brain tumors are frequently heterogeneous when looked at under the microscope. Perfusion can help guide the neurosurgeon to obtain the most accurate biopsy sample of the tumor to optimize therapy after surgery. Perfusion can also help distinguish a brain metastasis, primary brain tumors, and an infectious process prior to surgery.
Exam Preparation: The technologist will interview you prior to scan to make sure you have no contraindications to being in the MRI scanner. Patients with braces or other metal near the head or neck may not be suitable for DSC because of the artifacts the metal can cause. Patients who have kidney problems may not be able to get MRI contrast without being consented by a radiologist. If you think you have problems with your kidneys please let the technologist and scheduler know. Blood lab values may be obtained prior to the MRI scan to determine if you can receive MRI contrast safely. Patients will be given an IV prior to entering the MRI scanner.
What to expect: DSC perfusion alone takes approximately 2 minutes of scanner time. While the contrast is being injected, the scanner is dynamically acquiring images through the brain. It is very important to remain very still during this portion of the examination. The study is done in conjunction with routine anatomic imaging.
Jeffrey M. Pollock, MD
Associate Professor of Neuroradiology