Slide 1BME 501 Lecture Notes – Apr 30Diagnosing CV Pathologies:Diagnosing CV Pathologies: RadiographyDiagnosing CV Pathologies: Ultrafast Computed TomographyDiagnosing CV Pathologies: Ultrafast Computed TomographyDiagnosing CV Pathologies: Ultrafast Computed TomographyDiagnosing CV Pathologies: CV Magnetic Resonance ImagingDiagnosing CV Pathologies: CV Magnetic Resonance ImagingDiagnosing CV Pathologies: CV Magnetic Resonance ImagingDiagnosing CV Pathologies: CV Magnetic Resonance ImagingDiagnosing CV Pathologies: CV Magnetic Resonance ImagingDiagnosing CV Pathologies: Quantum DotsDiagnosing CV Pathologies: Quantum DotsDiagnosing CV Pathologies: Quantum DotsDiagnosing CV Pathologies: Quantum DotsNanotechnology:Nanotechnology: Detecting Cardiac Necrosis INanotechnology: Detecting Cardiac Necrosis IINanotechnology: Promoting Cardiac Cell GrowthNanotechnology: Alternatives to Drug-Eluting StentsBME 501Advanced Topics in Biomedical SystemsSpring 2014Dr. Kay1BME 501 Lecture Notes – Apr 30BME Applications forCardiovascular Pathologies•Diagnosing CV Pathologies•NanotechnologyDiagnosing CV Pathologies:•Heart poses unique challenges for imaging•Need high temporal resolution to accurately image heart perpetually in motion•Need high spatial resolution to accurately image small structures of heartDiagnosing CV Pathologies:Radiography•Uses X-rays to view non-uniformly composed material•Beam of X-rays projected toward object•Density and composition of each region determine how much of beam absorbed•X-rays that pass all the way through object are captured on other side by detector •Detector gives 2D representation of all structures superimposed on one anotherDiagnosing CV Pathologies:Ultrafast Computed TomographyIndications•Diagnosis of suspected coronary artery disease•Follow-up for coronary artery bypass graft (CABG)•Evaluation of valvular abnormalities and cardiac massesContraindications•Pregnancy •Allergy to/inability to handle iodine in contrast agent•Arrhythmias, tachycardia, coronary artery stentsDiagnosing CV Pathologies:Ultrafast Computed TomographyProcedure•Patient injected with intravenous contrast agent (iodine-based)•Patient lies on motorized table and moved through short, circular chamber•Multiple X-rays taken as X-ray source rotates around patient•X-ray sensors move to remain positioned opposite the X-ray source•One full rotation usually consists of 20-30 imaging eventsDiagnosing CV Pathologies:Ultrafast Computed TomographyProcedure•Data processed to construct cross-sectional or 3D images •Multiple rows of detectors allow for multiple cross-sections to be captured simultaneously•Sub-second rotation combined with multi-slice capture provide high temporal and spatial resolution•EKG-gating allows correlation of CT data with phases of cardiac cycleDiagnosing CV Pathologies:CV Magnetic Resonance ImagingIndications•Initial evaluation and follow-up of congenital heart disease–Assessment of shunt size–Evaluation of abnormal structures of heart•Diagnosis and follow-up of acquired heart disease–Planning stenting of aortic aneurysm–Assessment of vasculature of heart–Assessment of ventricular function and mass–Detection of coronary artery disease–Detection/assessment of MI & myocardial viabilityDiagnosing CV Pathologies:CV Magnetic Resonance Imaging•Non-invasive•Uses radio waves, magnets, and computer processer•Does not use ionizing radiation, does not carry risk of causing cancer•Creates both still and moving pictures of heart and major blood vesselsDiagnosing CV Pathologies:CV Magnetic Resonance ImagingProcedure•Patient placed within long tube of MRI scanner•Strong, stable magnetic field generated around area to be imaged•Three gradient magnets produce lower strength, variable fields for specific regions•Multiple radiofrequency coils transmit radio waves into specific regions of patient’s bodyDiagnosing CV Pathologies:CV Magnetic Resonance ImagingProcedure•Hydrogen atoms are abundant in the human body •When strong magnetic field applied, hydrogen atoms line up in direction of the field•Hydrogen protons line up pointing at patient’s feet or head (about 50:50)•Hydrogen-specific radiofrequency (RF) pulse is directed toward body-region of interestDiagnosing CV Pathologies:CV Magnetic Resonance ImagingProcedure•Unmatched hydrogen protons absorb energy from RF pulse and spin in different direction•The RF pulse forces them to spin at particular frequency, in particular direction•The three gradient magnets turn on and off rapidly to alter main magnetic field on local level•When RF pulse turned off, hydrogen protons return to resting state by releasing energy that is picked up by detection coils of machineWith targeted contrast, areas of infarction appear bright white (fat around heart also appears white)2.1 nm 7.5 nmDiagnosing CV Pathologies:Quantum Dots•Nanocrystals made of semiconductor material on order of 1-10 nm•So small that certain quantum phenomena become dominant•Act like artificial atoms–Can have a few electrons or several thousand–Energy levels are quantized due to confinement of electronsDiagnosing CV Pathologies:Quantum DotsProperties•Quantum confinement allows only for discrete energy levels•Energy levels depend on size of quantum dotsDiagnosing CV Pathologies:Quantum DotsFabrication•Self-assembly: quantum dots nucleate spontaneously when material is grown on a substrate not lattice matched•Viral assembly: genetically engineered bacteriophage viruses direct construction of quantum dots•Electrochemical assembly: ionic reaction at an electrolyte-metal interface results in spontaneous assembly of nanostructures•Laser production: laser directed at solid object generates quantum dotsDiagnosing CV Pathologies:Quantum DotsBio-Imaging Applications•Tagging of biomolecules allows for–Tracing drug-delivery–Locating tumors/abnormal tissues–Identifying metabolic abnormalities–Tracking movements of molecules in live cells•Advantages vs. organic dyes–Longer life (minimal degradation)–Can emit whole spectrum–Brighter–Useful at multiple scalesNanotechnology:•Engineered functional systems at the molecular scale•Altering scale alters properties of material•Risks–Nanoparticles readily absorbed into body–Reactivity increased–Toxicity unknownNanotechnology:Detecting Cardiac Necrosis I•Dying cardiac cells release specific proteins into