Presentation on theme: "Multimodality Imaging (MRI, PET, CT, etc..) Jonathan Dyke, Ph.D. Assistant Research Professor of Physics in Radiology Citigroup Biomedical Imaging Center."— Presentation transcript:
Multimodality Imaging (MRI, PET, CT, etc..) Jonathan Dyke, Ph.D. Assistant Research Professor of Physics in Radiology Citigroup Biomedical Imaging Center Weill Cornell Medical College Sackler Institute for Developmental Psychobiology Summer Lecture Series July 9, 2009
Advantages: 1)CT completely eliminates the superimposition of images of structures outside the area of interest. 2) because of the inherent high-contrast resolution of CT, differences between tissues that differ in physical density by less than 1% can be distinguished. 3)data from a single CT imaging procedure consisting of either multiple contiguous or one helical scan can be viewed as images in the axial, coronal, or sagittal planes, depending on the diagnostic task. This is referred to as multiplanar reformatted imaging. In the ED it’s FAST!
CT Radiation Dose Diagnostic Advantage Vs. Increased Risk Cancer Assumes linear relationship between radiation dose and cancer risk (Controversial). Risk for pediatric patients developing cancer from CT scan is greater than adults. ~ 500 in every 600,000 scans. “CT is an extremely valuable tool, and nobody should hesitate to undergo CT when it is indicated.”
Roy, C.S., and Sherrington, C.S. 1890. On the regulation of the blood supply of the brain. J. Physiol. 11:85-108. 100 years pass….. Ogawa, S., Lee, T.M., Nayak, A.S., and Glynn, P. 1990. Oxygenation-sensitive contrast I magnetic resonance image of rodent brain at high magnetic fields. Magn. Reson. Med. 14:68-78.
Oxyhemoglobin is diamagnetic Deoxyhemoglobin is paramagnetic Neuronal activity->Less deoxyhemoglobin Less susceptibility difference between capillary vessel and brain tissue Longer T 2 * Signal increase in T 2 * Sequence How big an increase are we talking about? How does BOLD really work?
Blood Oxygen Level Dependent Signal Source: Buxton book Ch 17
Clinical Apps: Improving clinical procedures, e.g. presurgical planning for brain tumors Direct: Mapping of functional properties of adjacent tissue Indirect: Understanding of likely consequences of a treatment Understanding cognition Studying brain development Investigating brain physiology ** Henning – Minimally Conscious State
DCE-MRI & ANGIOGENESIS What role does neovasculature fill in tumor growth? (Goldman,1907) How far from a vessel can a tumor cell survive? (Thomlinson & Gray,1955) Does DCE produce any physiologically significant parameters?
Pharmacokinetic Modeling of Tracer Kinetics (Kety, 1951) v e dC e (t) = K trans (C p (t)-C e (t)) dt Cp
k ep Interstitial Lesion k el K in k 12 Plasma Intravascular Brix/Hoffman 2 Compartment Model Gd-DTPA 0.1 mM/kg