Molecular Imaging Technologies: from Cells to Humans Arion Chatziioannou Ph.D. Crump Institute for Molecular Imaging Department of Molecular & Medical Pharmacology David Geffen School of Medicine at UCLA Imaging Technologies PET SPECT sp pace CT MRI ti time Information Content Tag specific information, relevant to the state of the process Imaging can not only visualize, but quantitate the relevant process Molecular Imaging Targets/Probes MAb, Fragments Receptor Mapping Hormones Drugs and Ligands Peptides Accumulation via Phosphorylation [18F]FDG glut 4 Enzyme Activity: Inhibition, Conc., Synthesis Internalization Hexocinase DNA Accumulation via AA Transport or Protein Synthesis AAT Reporter Gene DNA Accumulation via DNA-Synthesis mRNA Oligonucleotides mRNA Binding mRNA Reporter Probe Molecular Imaging Probes Bioluminescence Imaging Luciferase (enzyme) + Luciferin (substrate) + energy Light Firefly Fi fl controls l production d i off both luciferase and luciferin Given an excess off substrate Gi b t t thousands of photons can be produced per enzyme The Imaging g g Chamber CCD Chip Optical Filter wheel Shutter Ω ~ 1% QE ~90% Lens and Aperture Illuminator Heated Sample Stage Electronics Depth (mm) Standard Images are composed of two datasets Photographic g p + Luminescent Overlay y Optical p and PET Imaging g g Anterior view Posterior view • Human metastatic melanoma tumor model • triple fusion protein (luminescence, (luminescence fluorescence fluorescence, PET) PET Sensitivity • No collimators necessary: 100% efficiency possible • Stopping power of 1cm LSO ~30% P(A, B) = P(A)∩P(B) = P(A)*P(B) • • • Coincidence C i id stopping t i iis ~10% 10% Solid angle is ~50% In practice 5-10% sensitivity 9 8 7 6 5 4 3 2 1 0 Sensitivity % 1997 2000 Year 2004 2007 Dynamic Range The range of activities encompasses >10 log orders e±/sec 1 pCi • • 100 103 106 1 nCi High Sensitivity Cell cultures have uptakes on the order of pCi/cell (0.1 e±/sec) Ph Phosphorylation h l ti – assays have h on the order of (0.1 e±/sec) 1 μCi • • 109 1 mCi High Hi h Flexibility Fl ibilit Probe synthesis produces >mCi of activity (~108 e±/sec) In-vivo imaging >1nCi Different technologies completely cover this large spectrum. Microfluidics Operation Mechanism of a Pressure-Driven Valve Valve open Valve close Pressure Flow microfluidics: Chemical Synthesis Biological Assays Cell cultures M.A. Unger, H. P. Chou, T. Thorsen, A. Scherer, S. R. Quake, Science 2000, 288, 113. Direct Beta Detection Detector Cross-section Key Parameters: 1. Thin substrate allows detection of low energy betas 2. Thick detector will absorb more energy from incoming betas PSAPD Detection Limits, Linearity microfluidic chip PSAPD Cell Culture and FDG Uptake ~72 Cells A549 cell line microfluidic chip array Loading of FDG solution into Cell Chambers Movie plays x6 faster than real time Cell Culture System: Sensitivity ~80 cells 3-5 cells Activity per c cell (pCi/Cell) 350 300 250 200 150 100 50 0 1 cell 2 cells 3-5 cells N cells Number of Cells 1 cell Intracellular FDG concentration: 25nmol • 20 minute acquisition, 1mCi/cc FDG • System S t can quantify tif the th FDG uptake t k off 1 cell ll Translational Molecular Imaging Molecular In vitro Clinic In vivo Small Animal PET Systems Si Siemens Phili Philips GE Medical Mediso Gamma Medica Comecer Oxford Positron Results (volumetric projections) Negative control • HSV-tk positive mouse Time lapse movies of the tracer distribution Results - Time Activity Curves 7000 Heart 6000 Kidney Activity Coronal slices through individual framesBladder of the time lapse movie for 5000 Liver the HSV-tk positive mouse 4000 3000 2000 1000 0 0 50 100 150 Time (sec) 200 250 300 Conclusions • Molecular Imaging “Seeks to advance our understanding of biology and medicine through noninvasive i i in i vivo i investigation i ti ti off cellular ll l molecular l l events involved in normal and pathologic processes” (Society of Molecular Imaging) • Requires a mutually educating collaborative environment that includes biologists, physicists, chemists mathematicians, chemists, mathematicians physicians and clinicians • Physicists and engineers provide expertise in the development p and usage g of state of the art imaging g g tools for biologists • Devise and develop new tools that will answer important biological questions M Phelps E Hoffman S Cherry S Gambhir H Herschman N Satyamurthy T Ribas J Czernin O Witte W Weber P Michel J Heath L Wu J Barrio G Small S Devos D I Mellinghoff C Radu T Graeber H Tseng A Wu C Shen M Van Dam C Wu H Huang D Stout R Silverman R Sumida J Edwards W Lladno A Liu D Truong V Dominguez and R Taschereau G Alexandrakis D Prout F Rannou YC Chun Y Shao P Ray F Berger V Kenanova T Olafsen PL Chow Y Tai N Vu Z Tak For Yu J Shu J Cho Q Bao A Douraghy N Karakatsanis A Loening L i B Bai also Siemens Preclinical Solutions Radiation Monitoring Devices NIH – NCI, NIBIB, DOE, JCCC