Ultrasound Imaging (Contrast Agents and Therapy) - PowerPoint Presentation

1. Ultrasound Imaging(Contrast Agents and Therapy)BIOE 477/598DP

2. High echogenicity Low attenuation Low blood solubility Low diffusivity Ability to traverse pulmonary system Lack of biological effects in repeat exposuresIdeal Characteristics of an Ultrasound Probe

3. Contrast Agents and Their Distribution Relative to the Vascular Endothelial Cells

4. Diagram illustrating development stage of microbubbles, nanobubbles, and nanodroplets for diagnostic and therapeutic purposes. HIFU = high-intensity focused ultrasound; KDR = kinase domain receptor.

5. Laplace PressureIs the pressure difference between two sides of a curved surface Arises from surface tension γ of the interface For spheres, Young-Laplace equation reduces to the second equation Smaller droplets have nonnegligible extra pressure Commonly used for air bubbles in water or oil bubbles in water

6. Lindner JR. Microbubles in medical imaging: current applications and future directions. Nat Rev Drug Discov. 2004 Jun;3(6):527-32. Microbubbles Response to USMicrobubbles volumetrically oscillate due to continuous changes in the external pressure caused by an acoustic sound wave. At high pressure amplitudes, microbubbles collapse violently, producing water jetting and shock waves, and other inertial phenomena.

7. A slow motion capture of interial cavitations of micro bubblesRight frame: Image using both tissue and contrast agent fundamental frequency backscatter Left frame: the fundamental tissue signal has been filtered leaving the higher harmonic signal corresponding only to the contrast agent and, subsequently, the blood flow of the liver.Contrast harmonic image of liver in vivo

8. Lindner JR. Microbubles in medical imaging: current applications and future directions. Nat Rev Drug Discov. 2004 Jun;3(6):527-32. Acoustic Properties of Microbubbles

9. Non Linear Response of the Microbubble

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11. Microbubble Contrast AgentsNameManufacturerShellGasMean Size (µm)AlbunexMolecular BiosystemsAlbuminAir4.3OptisonMallinckrodt/AmershamAlbuminOctafluoropropane2-4.5DefinityBristol-Myers SquibbLipid/surfactantOctafluoropropane1.1-3.3ImagentImacorLipid/surfactantN2/perfluorohexane6.0SonovueBracco DiagnosticsLipidSulphur hexafluoride2-3LevovistSchering AGLipid/GalactoseAir2-4

12. Bubbles coalescing in the extravascular space become detectable by US due to their micron sized collectionsOrthotopically implanted human breast adenocarcinoma xenograft (MDA-MB-231 cells) in nude mouse imaged following intravenous administration of 5×107 VEGFR2-targeted probe. Scale bar =3 mmUltrasonic Molecular Imaging of Tumor Angiogenesis in Breast Cancer

13. AlbunexAir-filled sonicated albumin MBs (MBI, San Diego, California)1994: First ultrasound CA approved for use in USAlbumin shell designed to prevent outward diffusion of air from MBsSubstantial loss of gas volume occurred during transit to systemic circulation following intravenous injectionMarkedly decreased contrast enhancement and short duration of clinically useful contrast

14. Newer AgentsNewer agents designed to improve intravascular stabilityModifications in shell and gas content“Air-tight” polymer shells or lipid-galactose stabilized shells designed to minimize outward diffusion of gasUse of gases less prone to outward diffusion than airInert high-molecular-mass gases with low diffusion coefficients and low solubility in water (low Ostwald coefficient); result in prolonged lifespan of MBs

15. OptisonTMPerflutren Protein-Type A Injectable MicrospheresGE Healthcare, Buckinhamshire, UKOctafluoropropaneManufacturer has voluntarily suspended marketing since 2005http://www.amershamhealth-us.com/optison/monograph/om03-02.htmlOptison with RBCsStructural Formula

16. DefinityFDA approval in 2001Bristol-Myers Squibb Medical Imaging, Billerica, MA$65 million in sales in 2006More than 2 million patients dosed

17. How Do We Make These Bubbles?

18. SEM photograph of MBs (50 000×)

19. Subcutaneous human ovarian adenocarcinoma xenograft tumor (arrows) imaged with targeted contrast-enhanced ultrasound imaging after intravenous injection of integrin-targeted (A) and MB- (control) (B). Imaging signal obtained after MB-targeted injection was substantially higher than that obtained after control injection.

20. The prepared nanoparticles in vitro released the drug steadily for 72 hours without occurrence of burst release.DocetaxelMBs Loaded with Chemotherapeutics

21. Influence of ultrasound exposure on tumor temperatureAfter ultrasound exposure, the tumor temperature increased steadily in a time dependent manner.The growth curve of hepatocellular carcinoma xenografts.The tumor volume increased persistently in model group, while in all the docetaxel treated groups, the tumor volume increment was inhibited, especially in the GDN+UE group.

22. Bubble diameter (2r) (µm) (Pa) (atm)10002880.002843.0960000.9470.39600009.474The Laplace pressure is the pressure difference between the inside and the outside of a curved surface. The pressure difference is caused by the surface tension of the interface between liquid and gas.The Laplace pressure is determined from the Young–Laplace equation given as where  R1   and  R2   are the radii of curvature and    is the surface tension. Laplace Pressure

23. Phase-change contrast agents (PCCAs) Consist of perfluorocarbons (PFCs) that are initially in liquid form, but can then be vaporized with acoustic energy. Exposing pre-formed PFC micro bubbles to decreased ambient temperature and increased ambient pressure results in condensation of the gaseous core. The decreased size results in an increased Laplace pressure, which serves to preserve the particle.

24. Phase-change contrast agents (PCCAs) Exposing pre-formed PFC micro bubbles to decreased ambient temperature and increased ambient pressure results in condensation of the gaseous core. The decreased size results in an increased Laplace pressure, which serves to preserve the particle in the PCCAs take advantage of the volumetric increase that occurs during vaporization. Microscale droplets limited to flow in the vascular space have been proposed for a number of techniques, including temporary occlusion of blood vessels and enhancing cavitation activity. PCCAs manufactured with diameters in the 100-nm range may be able to diffuse out by EPR before phase-transitionContrast-enhanced extravascular imaging, cell-specific targeting, drug delivery, and therapy via ultrasound.

25. A microscale droplet of MBs exposed to a 0.25 µs pulse at approximately 0.55 MPa vaporizes to form a gas bubble approximately 5-fold larger

26. Bright field (a, c) and fluorescence (b, d) microscopy illustrating that the shell is preserved when DiI-labeled DFB microbubbles (a, b) are condensed to the liquid state (c, d), the shell is preserved through the change in volume.

27. Schematic illustration of drug transfer from nanodroplets through microbubbles into cells under the action of ultrasound.PFP/PEG-PLLA microbubbles in a plasma clot before (A) and after sonication for 1 min by 1-MHz, 3.4 W/cm2 (B) and 90-kHz, 2.8 W/cm2 ultrasound (C) at room temperature.Therapy with PCCA

28. Fig. 2A. PEG-PCL nanodroplets inserted in PBS through a 18 G needle (left) or 26 G needle (right). Bubbles formed when nanoemulsion is injected through a thin needle are visualized as bright spots (indicated by arrows in the right panel); bubbles rise to the sample surface while droplets precipitate to the bottom of a test tube.Fig. 2B. PEG-PCL nanodroplets injected in the agarose gel through a 18 G (left) or 26 G (right) needle. Injection through the thin needle results in immediate formation of very bright bubbles whose size and brightness increase with time; the brightness of the droplets also increases with time suggesting a post-injection droplet-to-bubble transition.

29. Photographs of a mouse bearing two ovarian carcinoma tumors (A) - immediately before and (B) - three weeks after the treatment; a mouse was treated by four systemic injections of nanodroplet-encapsulated PTX, nbGEN (20 mg/kg as PTX) given twice weekly; the right tumor was sonicated by 1-MHz CW ultrasound (nominal output power density 3.4 W/cm2, exposure duration 1 min) delivered 4 hours after the injection of the drug formulation. Ultrasound was delivered through a water bag coupled to a transducer and mouse skin by Aquasonic coupling gel.

30. Effective regression of the ovarian carcinoma tumor treated by nbGEN/ultrasound combination. The first photograph was taken before the start of the treatment, the second – two weeks later, i.e. immediately after the last treatment of the first treatment round. The third photograph was taken one week after the completion of the first treatment round. Normalized tumor growth/regression curve for the mouse.

31. Bubble-mediated Gene Delivery

32. US and Bubble-mediated Drug Delivery Through BBB

33. Ultrasound and pH Dually Responsive Polymer Vesicles for Anticancer Drug DeliveryUpon ultrasound radiation, the disruption and re-self-assembly lead to smaller vesicle. Upon decreasing the solution pH, the shrinkage of vesicles by the recrystallization of PTMA chains surpasses the swelling of vesicles by the partial protonation of DEA, leading to smaller vesicles. Further decreasing the solution pH will lead to the complete protonation of DEA and finally the disassembly of vesicles. Both ultrasound radiation and decreasing pH can lead to faster drug release.

34. A) Recanalization was observed in angiograms taken post-HIFU treatment. 2/4 (50%) of animals treated with 415 W power, exhibited recanalization when compared to post-stroke angiograms. There was no damage or leakage from the vessel apparent on the angiogram. B) Post-treatment H&E showed no evidence of tissue damage or hemorrhage due to HIFU in the region of sonication or in the surrounding brain tissue. Scale bar = 500 µm. C) Prussian blue staining was used to detect small fragments of the disrupted iron-loaded blood clots. doi:10.1371/journal.pone.0042311.g003

35. Intravital fluorescence images of subcutaneous pancreatic tumors before and after FUS treatment

36. (A) and (B) – two coronal slices in the 19F MR images superimposed on the low resolution proton anatomic images of a pancreatic tumor bearing mouse. A 2% PFCE nanoemulsion stabilized with PEG-PCL copolymer was systemically injected every two hours, 200 μl each. Four injections were given, for a total of the PFCE dose of 2 mmol/kg. Images were recorded an hour after the last nanodroplet injection (seven hours after the start). (C)- Multiple liver metastases (arrows) are revealed at the necropsy of the mouse (indicated by long thing arrows). Transparent large tumor is indicated by a thick arrow. Organs could be displaced at necropsy.

37. Dramatic regression of a breast cancer MDA MB231 tumor treated by four systemic injections of paclitaxel loaded 1% PFCE/0.25% PEG-PCL nanoemulsion and focused 1-MHz CW ultrasound applied for 60 s

38. FDA “Black Box” WarningIssued on October 10, 2007Post-marketing reports of 11 deaths 1-12 hours following administration of perflutren-based contrast agents10 patient deaths following Definity injection and 1 death following Optison injection4 patient deaths temporally related to contrast injectionPerflutren-based compounds contraindicated for use in patients with: 1. Acute coronary syndromes 2. Acute myocardial infarction 3. Worsening or clinically unstable heart failurehttp://www.fda.gov/cder/drug/InfoSheets/HCP/microbubbleHCP.htm

39. Safety DataAdverseExperiencePlacebo (n=42)5 ul/kg(n=85)10ul/kg(n=85)All Perflutren (n=169)Headache3 (7%)4 (5%)5 (6%)9 (5%)Dizziness1 (2%)2 (2%)1 (1%)3 (2%)Back Pain003 (4%)3 (2%)Nausea02 (2%)1 (1%)3 (2%)Flushing002 (2%)2 (1%)Chest pain002 (2%)2 (1%)Pruritis01 (1%)1 (1%)2 (1%)Rash01 (1%)1 (1%) 2 (1%)Sweating01 (1%)1 (1%) 2 (1%)IV Site Pain1 (2%)1 (1%)01 (1%)Fatigue1 (2%)1 (1%)0 1 (1%)Kitzman DW, Goldman ME, Gilliam LD, Cohen JL, Aurigemma GP, Gottdiener JS. Efficacy and safety of the novel ultrasound contrast agent perflutren (definity) in patients with suboptimal baseline left ventricular echocardiographic images. Am J Cardiol. 2000 Sep 15;86(6):669-74.

40. Safety DataNo clinically significant change in physical examination, vital signs, electrocardiographic tracings, or chemistry or hematology laboratory valuesAdverse event rates similar across treatment groups30 of 169 patients (18%) in the combined perflutren-treated group (15% in the 5 ml/kg group and 20% in the 10 ml/kg group)6 of 42 placebo-treated patients (14%)Headache was most frequently reported adverse event (9 of 169 patients who received perflutren (5%) and 3 of 42 patients who received placebo (7%)Kitzman DW, Goldman ME, Gilliam LD, Cohen JL, Aurigemma GP, Gottdiener JS. Efficacy and safety of the novel ultrasound contrast agent perflutren (definity) in patients with suboptimal baseline left ventricular echocardiographic images. Am J Cardiol. 2000 Sep 15;86(6):669-74.

41. “Pseudocomplication”Main ML, Goldman JH, and Grayburn PA. Thinking outside the “Box”—the ultrasound contrast controversy. J Am Coll Cardiol 2007; 50 (25): 2434-2437.Complications occurring after a medical procedure may be due to either the procedure itself or due to progression of the underlying disease stateMajor cardiovascular events are more likely to occur in patients who are “ill enough” to require diagnostic testingEchocardiography often the test of choice (or the only test available) for critically ill patients (shock, hypotension, tamponade, etc.)Association of adverse events following contrast administration does not establish causality