Introduction to Neuroradiology Chis. lee MID Professor of radiology and Neurosurgery Director of International education USC Keck School of Medicine University of Southern California
Introduction to Neuroradiology Chi S. Zee, MD Professor of Radiology and Neurosurgery Director of International Education USC Keck School of Medicine University of Southern California
Objectives Introduction to basics of X-ray ct and mri Imaging Basic overview of hemorrhage stroke, vascular malformation and intracranial tumors Introduction to MRI, CT and angiographic evaluation of the aforementioned pathologies o Introduction to advance imaging modalities such as diffusion, perfusion, MRA, MRV, MR spectroscopy and functional imaging
Objectives • Introduction to basics of X-ray, CT and MRI imaging • Basic overview of hemorrhage, stroke, vascular malformation and intracranial tumors. • Introduction to MRI, CT and angiographic evaluation of the aforementioned pathologies • Introduction to advance imaging modalities such as diffusion, perfusion, MRA, MRV, MR spectroscopy and functional imaging
Magnetic Resonance Imaging MR uses strong magnetic fields to generate Rages, If the body is exposed to a strong field, the free protons will align with the field and resonate at a certain frequency Then a radio frequency pulse can be applied, knocking the protons off axis. As the protons return to baseline they release signal which can be turned into images Each tissue has T1 and t2 properties with different recovery times
Magnetic Resonance Imaging • MR uses strong magnetic fields to generate images. • If the body is exposed to a strong field, the free protons will align with the field and resonate at a certain frequency. • Then a radio frequency pulse can be applied, knocking the protons off axis. As the protons return to baseline they release signal which can be turned into images. • Each tissue has T1 and T2 properties with different recovery times
TI weighted image---high signal Fat Blood (methemoglobin) High concentration of protein
T1 weighted image---high signal • Fat • Blood (methemoglobin) • High concentration of protein
可 weighted image- low signa‖ o Fluid Edema Ai o Calcification o Flowing blood
T1 weighted image--- low signal • Fluid • Edema • Air • Calcification • Flowing blood
T2 Weighted image---high signal o Fluid Edema o Fat Blood (extracellular methemoglobin
T2 weighted image---high signal • Fluid • Edema • Fat • Blood (extracellular methemoglobin)
T2 Weighted image---low signal Air Calcification 月 owing blood o Very high concentration of protein Fungus o Metal
T2 weighted image---low signal • Air • Calcification • Flowing blood • Very high concentration of protein • Fungus • Metal
Tissue Contrast parameter on MR Imaging TI relaxation time 丁2 relaxation time Proton density Diffusion of water
Tissue Contrast Parameter on MR Imaging • T1 relaxation time • T2 relaxation time • Proton density • Diffusion of water
FLAIr IMAGING A heavily T2 weighted image with suppression of CSF signal intensity A 180 degree pulse with an inversion time of 2500 ms tailored to null CSF signal o Greater conspicuity of lesions at the csf-brain interface
FLAIR IMAGING • A heavily T2 weighted image with suppression of CSF signal intensity • A 180 degree pulse with an inversion time of 2500 ms tailored to null CSF signal • Greater conspicuity of lesions at the CSF-brain interface
Diffusion Weighted Imaging Diffusion of water is random---isotropic White matter tracts---anisoptropic, or directional Highly sensitive to motion o Intracellular water(restricted water)is not susceptible to the diffusion gradients Mobile water loses signal intensity due to dephasing
Diffusion Weighted Imaging • Diffusion of water is random---isotropic • White matter tracts---anisoptropic, or directional • Highly sensitive to motion • Intracellular water (restricted water) is not susceptible to the diffusion gradients • Mobile water loses signal intensity due to dephasing
