Neuroimaging Lecture

8. What is a MRI? MRI stands for magnetic resonance imaging. A MRI scanner has a magnetic field that is frequently up to 60,000 times as strong as Earth’s magnetic field! MRI equipment is expensive. 1.5 tesla scanners often cost between $1 million and $1.5 million USD. 3.0 tesla scanners often cost between $2 million and $2.3 million USD. Construction of MRI suites can cost up to $500,000 USD, or more, depending on project scope. Dangers of MRI's Video: http://www.youtube.com/watch?v=_lBxYtkh4ts

17. Pooley, R. A. Radiographics 2005;25:1087-1099 T1-weighted contrast In the brain T 1 -weighted scans provide good gray matter/white matter contrast , in other words put simply, T1 Weighted Images highlights fat deposition. Types of MRI images: T1WI

18. Pooley, R. A. Radiographics 2005;25:1087-1099 T2-weighted contrast Types of MRI images: T2WI T2 images are particularly well suited to edema as they are sensitive to water content (edema is characterized by increased water content). In other words, put more simply, T2 weighted images light up liquid on the images being visualized .

19. Magnetic Resonance Angiography (MRA) is a group of techniques based on Magnetic Resonance Imaging (MRI) to image blood vessels . MRA generates pictures of the arteries to evaluate them for stenosis (abnormal narrowing) or aneurysms (vessel wall dilatations, at risk of rupture). A variety of techniques can be used to generate the pictures, such as administration of a paramagnetic contrast agent ( gadolinium, Gd ). Types of MRI images: Magnetic resonance angiography (MRA) Magnetic Resonance Angiography: Maximum intensity projection of an MRA covering from the top of the heart to just below the circle of Willis MRA showing the circle of Willis in the brain.

20. Material to read latter-T 1 vs T 2 MRI: Tissue Appearance WT FAT H2O MUSC LIG BONE T1 B D I D D Proton Density I I I D D T2 I B I D D

21. Material to read latter-T 1 vs T 2 MRI: Tissue Appearance

32. Wilson’s disease Das SK and Ray K (2006) Wilson's disease: an update Nat Clin Pract Neurol 2: 482 – 493 10.1038/ncpneuro0291 Hyperintensities due to copper deposition in the bilateral basal ganglia and thalami shown by T2-weighted MRI of the brain

33. Radiology: Glioblastoma is usually seen as a grossly heterogeneous mass . R ing enhancement surrounding a necrotic center is the most common presentation, but there may be multiple rings. Characterized by irregular ring-enhancement surrounding a central non-enhancing region of necrosis . Note the shaggy inner-margin of the ring, and the remarkable variation in its thickness. The small foci of internal enhancement represent islands of living tumor within the regions of necrosis . Surrounding vasogenic edema can be impressive, and adds significantly to the mass effect. Glioblastoma multiforme ( GBM) Axial Gd Enhanced T1W MRI Axial T2W MRI

34. MRI appearance two months after whole brain radiation (small lesions gone and large lesion much smaller) Metastatic brain tumors

37. Multiple sclerosis (MS) Axial Gd Enhanced T1W MR Axial T2W MR MRI imaging of the brain Gd enhanced helps diagnose MS. Typical MS white matter lesions are bright lesions on T2-weighted image (left image), especially in the corpus callosum and periventricular regions. T2W axial T2W sagittal