12/21/2016. Siemens Medical Systems Research Agreement Philips Healthcare Research Agreement AAN and ASN Committees

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1 Joseph V. Fritz, PhD Nandor Pintor, MD Dent Neurologic Institute ASN 2017 Friday, January 20, 2017 Siemens Medical Systems Research Agreement Philips Healthcare Research Agreement AAN and ASN Committees MRI Internal source (protons) encode soft tissue character Tomographic Acquisition any Plane 3 Tesla, 80 mt/m, 200 T/m/s, min TR, min TE 4 W/kg, Magnetic force CT External source (x-ray) encode tissue density Tomographic Acquisition Axial Plan, MPR any Plane mm, 250ms rotation, dose reduction 3 millisieverts nature 50 msv annual limit CT Keep Similar to Background Reformating Dynamic / Functional Imaging Tissue Characterization Single Rotation for Full Volume (16cm) Multi-Spectral MRI Speed Artifact Reduction Functional and Metabolic Imaging Field Strength (SNR, Speed, Resolution) Parallel Receive and Transmit MRI Contrast or Non-Contrast 0.5 x 0.5 x 1 mm 3 Flow and Metal Artifacts Minutes Advances in fast dynamics, functional, artifact reduction CT Contrast (+pre if subtraction) 0.5 x 0.5 x 0.5 mm 3 Stent/Ca artifacts Seconds Advances in bone removal, dynamics 1

2 Radio/TV Xray Microwaves Visible Photoelectric Dominates Soft Tissue Attenuation Harder beam, More penetration Compton Dominates Dense Material Attenuation (Bone, Iodine) J. Nucl. Med. Technol. March 1, 2005 vol 33 no Stretch the Slinky Faster, less dose Blurred slices 2

3 Detector Dimension FoV / Matrix (eg 0.5mm in Brain) Single Rotation 320 detector row CT coverage Single Rotation 64 detector row CT coverage Single Rotation 160 detector row CT coverage 4 cm 8 cm 16 cm 3

4 Review Tissue HU Air Lung -500 Fat -100 to -50 Water 0 CSF +15 Blood +30to + 45 Muscle +1- to +40 Grey Matter +37 to +45 White Matter +20 to +30 SoftTissue, Contrast +100 to +300 Bone +700 (Cancerous) to (dense bone) 125 mas 200 mas CT Index: Radiation from the Tube (CTDI, in mgy) Increases with Current (ma), time (s, ma*s), Voltage (kv) Need less if Detector more sensitive, less overlap, etc -Length Product (DLP, in mgy*cm) Total Amount of Radiation The Body Multiply times Coverage in cm Peds: 2-5x more Effective on a Person in millisieverts(msv) Amount of Radiation Absorbed (IT IS CUMULATIVE) Multiply DLP/1000 by k-factor (2.2 in head, 5 in neck, 15 in body) egbackground < 3 msv; Professionals < 50 msv / Year Exam Effective Body (msv) Absorbed Organ (mgy) Annual Background* Chest x-ray Head CT Screening Mammo Abdomen CT 8 14 Chest CT CT Colonography 6 11 Chest-Ab-Pelv CT Cardiac CT Barium enema Neonatal AbdominalCT *99% less than 7 msv per year 4

5 Tube Modulation Detector Material Filtering 4 slice 16 Slice New Recon Methods 64 Slice ECG Modulation Filtering Dynamic 320 Slice, Active Collimation, Recon Iterative Reconstruction 256 Slice Innovations in Reconstruction Without With Iterative Recon CTDI mgy DLP mgy.cm Effective K CTDI mgy DLP mgy.cm Effective K msv msv Scan Mode Collimation Pitch kvp ma Rotation Time Scan Range CTDI mgy DLP mgy.cm Effective K Volume 0.5mm x 240 NA s 120mm msv Accessory Occipital Suture (31% dose compared to helical acquisition) Courtesy of Dr. Greenberg, Arkansas Children s Hospital 5

6 In direction of greatest attenuation 6

7 No temporal uniformity, rapid table movement Temporal uniformity, no table movement 7

8 rcbv rcbf MTT CBF = CBV MTT Scan Mode Collimation Pitch kvp ma Rotation Time Scan Range CTDI mgy DLP mgy.cm Effective K Dynamic 0.5mmx 320 * 80 maboost mm msv CBV = Autoregulation CBF = Low Flow TTP, Delay = Stenosis, Colateralization Tissue at risk: relative MTT optimal threshold of 145% Infarct core: absolute CBV optimal threshold 2.0 ml/100g Wintermark, Stroke. 2006; 37: MTT = vasodilation Courtesy Erin Angel, Toshiba 8

9 Differentiate Bone, Contrast CTA without bone removal Eliminate Calcification Artifact Metal Artifact Reduction Plaque Characterization Ratio of Detected HUs (RITRadiology.com) *AN Primak, et al, AJR:195, Nov 2010 Isotropic Voxels (Image in Any Plane) Wide detector array 320 x 0.5mm (640 x 0.25mm) Reduction Methods Faster Imaging Fast Gantry Rotation (0.25 s) Multiple X-ray Tubes Dynamic Imaging. Functional Assessment. Angio/Perfusion Artifact Reduction Multi-Energy 9