复旦大学上海医学院：《医学影像学》PPT教学课件_神经系统 Introduction to Neuroradiology.

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