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Yu EY, Chandrasekharan P, Berzon R, Tay ZW, Zhou XY, Khandhar AP, Ferguson RM, Kemp SJ, Zheng B, Goodwill PW, Wendland MF, Krishnan KM, Behr S, Carter J, Conolly SM. Magnetic Particle Imaging for Highly Sensitive, Quantitative, and Safe in Vivo Gut Bleed Detection in a Murine Model. ACS NANO 2017; 11:12067-12076. [PMID: 29165995 PMCID: PMC5752588 DOI: 10.1021/acsnano.7b04844] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Gastrointestinal (GI) bleeding causes more than 300 000 hospitalizations per year in the United States. Imaging plays a crucial role in accurately locating the source of the bleed for timely intervention. Magnetic particle imaging (MPI) is an emerging clinically translatable imaging modality that images superparamagnetic iron-oxide (SPIO) tracers with extraordinary contrast and sensitivity. This linearly quantitative modality has zero background tissue signal and zero signal depth attenuation. MPI is also safe: there is zero ionizing radiation exposure to the patient and clinically approved tracers can be used with MPI. In this study, we demonstrate the use of MPI along with long-circulating, PEG-stabilized SPIOs for rapid in vivo detection and quantification of GI bleed. A mouse model genetically predisposed to GI polyp development (ApcMin/+) was used for this study, and heparin was used as an anticoagulant to induce acute GI bleeding. We then injected MPI-tailored, long-circulating SPIOs through the tail vein, and tracked the tracer biodistribution over time using our custom-built high resolution field-free line (FFL) MPI scanner. Dynamic MPI projection images captured tracer accumulation in the lower GI tract with excellent contrast. Quantitative analysis of the MPI images show that the mice experienced GI bleed rates between 1 and 5 μL/min. Although there are currently no human scale MPI systems, and MPI-tailored SPIOs need to undergo further development and evaluation, clinical translation of the technique is achievable. The robust contrast, sensitivity, safety, ability to image anywhere in the body, along with long-circulating SPIOs lends MPI outstanding promise as a clinical diagnostic tool for GI bleeding.
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Affiliation(s)
- Elaine Y Yu
- Department of Bioengineering, University of California , Berkeley, California 94720, United States
| | - Prashant Chandrasekharan
- Department of Bioengineering, University of California , Berkeley, California 94720, United States
| | - Ran Berzon
- Department of Bioengineering, University of California , Berkeley, California 94720, United States
| | - Zhi Wei Tay
- Department of Bioengineering, University of California , Berkeley, California 94720, United States
| | - Xinyi Y Zhou
- Department of Bioengineering, University of California , Berkeley, California 94720, United States
| | - Amit P Khandhar
- Lodespin Labs, LLC , Seattle, Washington 98103, United States
| | | | - Scott J Kemp
- Lodespin Labs, LLC , Seattle, Washington 98103, United States
| | - Bo Zheng
- Department of Bioengineering, University of California , Berkeley, California 94720, United States
| | | | - Michael F Wendland
- Department of Bioengineering, University of California , Berkeley, California 94720, United States
| | - Kannan M Krishnan
- Lodespin Labs, LLC , Seattle, Washington 98103, United States
- Department of Materials Science, University of Washington , Seattle, Washington 98195, United States
| | - Spencer Behr
- Department of Radiology and Biomedical Imaging, University of California San Francisco , San Francisco, California 94143, United States
| | - Jonathan Carter
- University of California San Francisco Medical Center , San Francisco, California 94143, United States
| | - Steven M Conolly
- Department of Bioengineering, University of California , Berkeley, California 94720, United States
- Department of Electrical Engineering and Computer Sciences, University of California , Berkeley, California 94720, United States
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Bogdanov Jr AA, Mazzanti M, Castillo G, Bolotin E. Protected Graft Copolymer (PGC) in Imaging and Therapy: A Platform for the Delivery of Covalently and Non-Covalently Bound Drugs. Am J Cancer Res 2012; 2:553-76. [PMID: 22737192 PMCID: PMC3381344 DOI: 10.7150/thno.4070] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 02/17/2012] [Indexed: 12/13/2022] Open
Abstract
Initially developed in 1992 as an MR imaging agent, the family of protected graft copolymers (PGC) is based on a conjugate of polylysine backbone to which methoxypoly(ethylene glycol) (MPEG) chains are covalently linked in a random fasion via N-ε-amino groups. While PGC is relatively simple in terms of its chemcial composition and structure, it has proved to be a versatile platform for in vivo drug delivery. The advantages of poly amino acid backbone grafting include multiple available linking sites for drug and adaptor molecules. The grafting of PEG chains to PGC does not compromise biodegradability and does not result in measurable toxicity or immunogenicity. In fact, the biocompatablility of PGC has resulted in its being one of the few 100% synthetic non-proteinaceous macromolecules that has suceeded in passing the initial safety phase of clinical trials. PGC is capable of long circulation times after injection into the blood stream and as such found use early on as a carrier system for delivery of paramagnetic imaging compounds for angiography. Other PGC types were later developed for use in nuclear medicine and optical imaging applications in vivo. Recent developments in PGC-based drug carrier formulations include the use of zinc as a bridge between the PGC carrier and zinc-binding proteins and re-engineering of the PGC carrier as a covalent amphiphile that is capabe of binding to hydrophobic residues of small proteins and peptides. At present, PGC-based formulations have been developed and tested in various disease models for: 1) MR imaging local blood circulation in stroke, cancer and diabetes; 2) MR and nuclear imaging of blood volume and vascular permeability in inflammation; 3) optical imaging of proteolytic activity in cancer and inflammation; 4) delivery of platinum(II) compounds for treating cancer; 5) delivery of small proteins and peptides for treating diabetes, obesity and myocardial infarction. This review summarizes the experience accumulated by various research groups that chose to use PGC as a drug delivery platform.
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Quiroga Gómez S, Pérez Lafuente M, Abu-Suboh Abadia M, Castell Conesa J. [Gastrointestinal bleeding: the role of radiology]. RADIOLOGIA 2011; 53:406-20. [PMID: 21924440 DOI: 10.1016/j.rx.2011.03.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 03/14/2011] [Accepted: 03/15/2011] [Indexed: 12/30/2022]
Abstract
Gastrointestinal bleeding represents a diagnostic challenge both in its acute presentation, which requires the point of bleeding to be located quickly, and in its chronic presentation, which requires repeated examinations to determine its etiology. Although the diagnosis and treatment of gastrointestinal bleeding is based on endoscopic examinations, radiological studies like computed tomography (CT) angiography for acute bleeding or CT enterography for chronic bleeding are becoming more and more common in clinical practice, even though they have not yet been included in the clinical guidelines for gastrointestinal bleeding. CT can replace angiography as the diagnostic test of choice in acute massive gastrointestinal bleeding, and CT can complement the endoscopic capsule and scintigraphy in chronic or recurrent bleeding suspected to originate in the small bowel. Angiography is currently used to complement endoscopy for the treatment of gastrointestinal bleeding.
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Affiliation(s)
- S Quiroga Gómez
- Servicio de Radiodiagnóstico, Hospital Universitari Vall d'Hebron, Barcelona, España.
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Tian M, Wen X, Jackson EF, Ng C, Uthamanthil R, Liang D, Gelovani JG, Li C. Pharmacokinetics and magnetic resonance imaging of biodegradable macromolecular blood-pool contrast agent PG-Gd in non-human primates: a pilot study. CONTRAST MEDIA & MOLECULAR IMAGING 2011; 6:289-97. [PMID: 21861289 DOI: 10.1002/cmmi.431] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2010] [Revised: 10/28/2010] [Accepted: 10/30/2010] [Indexed: 11/08/2022]
Abstract
The purpose of this study was to evaluate poly(L-glutamic acid)-benzyl-DTPA-Gd (PG-Gd), a new biodegradable macromolecular magnetic resonance imaging contrast agent, for its pharmacokinetics and MRI enhancement in nonhuman primates. Studies were performed in rhesus monkeys at intravenous doses of 0.01, 0.02 and 0.08 mmol Gd/kg. T(1)-weighted MR images were acquired at 1.5 T using fast spoiled gradient recalled echo and fast spin echo imaging protocols. The small-molecule contrast agent Magnevist was used as a control. PG-Gd in the monkey showed a bi-exponential disposition. The initial blood concentrations within 2 h of PG-Gd administration were much higher than those for Magnevist. The high blood concentration of PG-Gd was consistent with the MR imaging data, which showed prolonged circulation of PG-Gd in the blood pool. Enhancement of blood vessels and organs with a high blood perfusion (heart, liver, and kidney) was clearly visualized at 2 h after contrast injection at the three doses used. A greater than proportional increase of the area under the blood concentration-time curve was observed when the administered single dose was increased from 0.01 to 0.08 mmol/kg. By 2 days after PG-Gd injection, the contrast agent was mostly cleared from all major organs, including kidney. The mean residence time was 15 h at the 0.08 mmol/kg dose. A similar pharmacokinetic profile was observed in mice, with a mean residence time of 5.4 h and a volume of distribution at steady-state of 85.5 ml/kg, indicating that the drug was mainly distributed in the blood compartment. Based on this pilot study, further investigations on the potential systemic toxicity of PG-Gd in both rodents and large animals are warranted before testing this agent in humans.
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Affiliation(s)
- Mei Tian
- Department of Experimental Diagnostic Imaging, The University of Texas M D Anderson Cancer Center, Houston, TX 77030, USA.
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Laurent S, Burtea C, Vander Elst L, Muller RN. Synthesis and characterization of new low-molecular-weight lysine-conjugated Gd-DTPA contrast agents. CONTRAST MEDIA & MOLECULAR IMAGING 2010; 6:229-35. [PMID: 21861283 DOI: 10.1002/cmmi.422] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 09/04/2010] [Accepted: 07/07/2010] [Indexed: 11/10/2022]
Abstract
Various blood pool contrast agents (CAs), characterized by intravascular distribution, have been developed to assist contrast enhanced magnetic resonance angiography (MRA). Among these CAs, the DTPA derivatives conjugated to synthetic polypeptides, such as polylysine, represent attractive candidates for blood pool imaging. However, due to the presence of charged residues located on their backbone, these agents are retained in the kidneys and this compromises their long blood half-life. In order to overcome this major drawback of the polylysine compounds, two new low-molecular-weight CAs were synthesized in the present work by conjugating four or six 1-p-isothiocyanatobenzyl-DTPA moieties to tri- or penta-Lys peptides [(Gd-DTPA)(4) Lys(3) and (Gd-DTPA)(6) Lys(5)], respectively. All the -NH(2) groups of Lys were thus blocked by covalent conjugation to DTPA. The stability and relaxometric properties of these compounds, as well as their pharmacokinetic and biodistribution characteristics, were then evaluated. The half-life in blood of these new polylysine derivatives, as determined in rats, is twofold longer than that of Gd-DTPA. The compounds could thus be optimal blood pool markers for MRA, which typically uses fast acquisition times. The absence of positive molecular charge did not limit their retention in kidneys 2 h after administration. On the other hand, (Gd-DTPA)(4) Lys(3) is retained in kidneys to a lesser extent than (Gd-DTPA)(6) Lys(5) . Their moderate retention in blood and their higher stability and relaxivity in comparison with Gd-DTPA highlight these polylysine derivatives as optimal compared with previously developed polylysine compounds.
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Affiliation(s)
- Sophie Laurent
- Department of General, Organic and Biomedical Chemistry, NMR and Molecular Imaging Laboratory, University of Mons, Avenue Maistriau 19, Mendeleev Building, B-7000 Mons, Belgium
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Chiribiri A, Morton G, Nagel E. Gadofosveset injection for magnetic resonance angiography. ACTA ACUST UNITED AC 2010. [DOI: 10.2217/iim.10.39] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hood MN, Ho VB. Contrast Agents: Innovations and Potential Applications for Body MR Angiography. Magn Reson Imaging Clin N Am 2005; 13:189-203, vii. [PMID: 15760765 DOI: 10.1016/j.mric.2004.12.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Maureen N Hood
- Department of Radiology and Radiological Sciences, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814-4799, USA.
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Lefkovitz Z, Cappell MS, Lookstein R, Mitty HA, Gerard PS. Radiologic diagnosis and treatment of gastrointestinal hemorrhage and ischemia. Med Clin North Am 2002; 86:1357-99. [PMID: 12510457 DOI: 10.1016/s0025-7125(02)00080-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Major breakthroughs in catheter, guidewire, and other angiographic equipment currently allow interventional radiologists to diagnose massive life-threatening upper and lower GI hemorrhage and to stop the bleeding safely and effectively using superselective catheterization and microcoil embolization. Similarly, the interventional radiologist can treat acute intestinal ischemia safely and effectively with selective catheterization and papaverine administration and treat chronic mesenteric ischemia by percutaneous angioplasty and stent placement. A multidisciplinary approach, including the gastroenterologist, radiologist, and surgeon, is critical in managing GI bleeding and intestinal ischemia, particularly in patients at high risk or presenting as diagnostic dilemmas.
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Affiliation(s)
- Zvi Lefkovitz
- Department of Radiology, Mount Sinai Medical Center, Mount Sinai School of Medicine, New York, NY, USA
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Wassef W, Obando J, Sharma A. Upper Gastrointestinal Bleeding of Nonvariceal Origin in the ICU Setting. J Intensive Care Med 2001. [DOI: 10.1046/j.1525-1489.2001.00105.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Wassef W, Obando J, Sharma A. Upper Gastrointestinal Bleeding of Nonvariceal Origin in the ICU Setting. J Intensive Care Med 2001. [DOI: 10.1177/088506660101600301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Upper gastrointestinal bleeding (UGI) is a common medical emergency in the intensive care unit (ICU). Although it can be caused by a number of gastrointestinal disorders, its management usually follows a few simple management rules. Prior to endoscopy, the key to management is to resuscitate the patient, to determine the need for airway protection, and to assess the need for transfusions according to the American Society of Gastrointestinal Endoscopy guidelines. During endoscopy, the key to management is to recognize the cause of the bleeding and to achieve hemostasis. Following endoscopy, the key to management is to determine the need for medical therapy and to determine a proper disposition for the patient given his potential risk for rebleeding. Stress-related erosions syndrome (SRES) is a disease that usually develops in the ICU setting and is known to be associated with a high degree of morbidity and mortality. Although it is approached in the same fashion as other causes of UGI bleeding, patients tend to do better if they are recognized early and treated prophylactically. Criteria for proper patient selection and the recommended prophylactic therapy are reviewed.
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Affiliation(s)
- Wahid Wassef
- Division of Digestive Disease and Nutrition, UMass Memorial Health Care, University of Massachusetts Medical School, Worcester, MA
| | - Jorge Obando
- Division of Digestive Disease and Nutrition, UMass Memorial Health Care, University of Massachusetts Medical School, Worcester, MA
| | - Ashish Sharma
- Division of Digestive Disease and Nutrition, UMass Memorial Health Care, University of Massachusetts Medical School, Worcester, MA
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Lefkovitz Z, Cappell MS, Kaplan M, Mitty H, Gerard P. Radiology in the diagnosis and therapy of gastrointestinal bleeding. Gastroenterol Clin North Am 2000; 29:489-512. [PMID: 10836191 DOI: 10.1016/s0889-8553(05)70124-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Major breakthroughs in catheter and guidewire design as well as improvements in angiographic x-ray equipment currently allow interventional radiologists to diagnose massive life-threatening upper and lower GI hemorrhage and to stop the bleeding safely and effectively using superselective catheterization and microcoil embolization. For chronic or recurrent GI bleeding, when endoscopy is unrevealing or equivocal, barium studies, CT scanning, nuclear medicine studies, and angiography can help determine the cause of bleeding. A multidisciplinary approach, including the gastroenterologist, radiologist, and surgeon, is extremely helpful in managing GI bleeding, particularly in high-risk patients or patients presenting as diagnostic dilemmas.
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Affiliation(s)
- Z Lefkovitz
- Department of Radiology, Mount Sinai Medical Center, New York, USA
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Bogdanov AA, Lewin M, Weissleder R. Approaches and agents for imaging the vascular system. Adv Drug Deliv Rev 1999; 37:279-293. [PMID: 10837740 DOI: 10.1016/s0169-409x(98)00098-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Several classes of vascular imaging agents are described: (1) liposome-based blood cell mimetics; (2) plasma protein mimetics; (3) small molecules that bind to plasma proteins in the circulation. The characteristic features of the different agents are described and critically compared, including the advantages and potential pitfalls of each individual type.
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Affiliation(s)
- AA Bogdanov
- Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Bldg. 149, 13th St., Boston, MA 02129, USA
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Zaharchuk G, Bogdanov AA, Marota JJ, Shimizu-Sasamata M, Weisskoff RM, Kwong KK, Jenkins BG, Weissleder R, Rosen BR. Continuous assessment of perfusion by tagging including volume and water extraction (CAPTIVE): a steady-state contrast agent technique for measuring blood flow, relative blood volume fraction, and the water extraction fraction. Magn Reson Med 1998; 40:666-78. [PMID: 9797148 DOI: 10.1002/mrm.1910400504] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A new technique, CAPTIVE, that is a synthesis of arterial spin labeling (ASL) blood flow and steady-state susceptibility contrast relative blood volume imaging is described. Using a single injection of a novel, long half-life intravascular magnetopharmaceutical with a high tissue:blood susceptibility difference (deltachi) to deltaR1 ratio, changes in tissue transverse relaxivity (deltaR2 or deltaR2*) that arise from changes in blood volume were measured, while preserving the ability to measure blood flow using traditional T1-based ASL techniques. This modification permits the continuous measurement of both blood flow and blood volume. Also, because the contrast agent can be used to remove the signal from intravascular spins, it is possible to measure the first-pass water extraction fraction. Contrast-to-noise is easily traded off with repetition rate, allowing the use of non-EPI scanners and more flexible imaging paradigms. The basic theory of these measurements, several experimental scenarios, and validating results are presented. Specifically, the PaCO2-reactivity of microvascular and total relative cerebral blood volume (rCBV), cerebral blood flow (CBF), and the water extraction-flow product (EF) in rats with the new contrast agent MPEG-PL-DyDTPA is measured, and the values are concordant with those of previous literature. As an example of one possible application, continuous flow and volume measurements during transient focal ischemia are presented. It is believed that CAPTIVE imaging will yield a more complete picture of the hemodynamic state of an organ, and has further application for understanding the origins of the BOLD effect.
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Affiliation(s)
- G Zaharchuk
- Harvard-MIT Division of Health Sciences and Technology, Harvard Medical School and MIT, Boston, Massachusetts, USA
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Callahan RJ, Bogdanov A, Fischman AJ, Brady TJ, Weissleder R. Preclinical evaluation and phase I clinical trial of a 99mTc-labeled synthetic polymer used in blood pool imaging. AJR Am J Roentgenol 1998; 171:137-43. [PMID: 9648777 DOI: 10.2214/ajr.171.1.9648777] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
OBJECTIVE To obtain initial data on the safety and efficacy of a novel polymeric, synthetic blood pool contrast agent [O-monomethoxypoly(ethylene glycol)-O'succinyl]poly(N-epsilon-L-lysyl [99mTc]diethylenetriamine pentaacetate monoamide, we performed a preclinical evaluation and phase 1 clinical trial under an investigator-sponsored investigational new drug application. MATERIALS AND METHODS Methoxypoly(ethylene glycol)ethylenetriaminopentaacetic acid was formulated into a kit containing the polymer, stannous chloride, and a buffer. Kits were stored in frozen form for subsequent labeling with technetium-99m. Acute and subacute toxicity studies were carried out in rats and rabbits. Healthy human volunteers (n = 6) were then enrolled in a prospective, open-label phase 1 clinical study. RESULTS Animal studies showed no signs of acute or subacute toxicity at doses 280 times the proposed dose for humans. In the clinical trial with humans, no significant abnormalities of laboratory values, ECG findings, or hemodynamic parameters were seen. One volunteer experienced facial flushing and palpitations. Four volunteers showed typical blood pool biodistribution, with a blood half-life of 20.6 +/- 2.3 hr. At 24 hr after administration, 22.1% +/- 2.5% of the injected dose had been excreted through the kidneys. Two other volunteers showed a different biodistribution (primarily to liver and spleen), presumably associated with labeling instability. CONCLUSION Synthetic methoxypoly(ethylene glycol)-grafted polymers can have long circulation times in humans. Pharmaceuticals based on such polymers are expected to have clinical applications in cardiovascular imaging, gastrointestinal bleeding studies, and capillary leak imaging.
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Affiliation(s)
- R J Callahan
- Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown 02129, USA
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Abstract
Over the last 10 years, the most significant advancement in imaging of the acute abdomen has been the development of helical CT imaging. Rapid breath-hold imaging and improved intravascular opacification have enabled radiologists to obtain volumetric data that can be viewed in smaller slice increments. Helical data can also be analyzed utilizing multiplanar and three-dimensional techniques. With its proven ability to diagnose a wide variety of conditions, CT remains the diagnostic modality of choice for imaging the surgical abdomen. There have been considerable improvements in image resolution in US with improvements in transducer technology. Ultrasonography often serves as the first study in evaluating the pediatric or female patient with right lower quadrant or pelvic pain. Computed tomography may be necessary if US is not diagnostic. Despite these technical advances, plain film radiography should be the first imaging study for suspected cases of bowel perforation or obstruction. Magnetic resonance imaging continues to evolve, with improvements in hardware and software design that allow for faster imaging, but current levels of availability in the acute setting preclude its wider use. Whereas further imaging is not necessary for patients presenting with classic signs and symptoms of various acute abdominal diseases, the atypical patient often requires careful diagnostic imaging. Close consultation between the radiologist and surgeon leads to studies appropriately tailored to meet the diagnostic challenge at hand.
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Affiliation(s)
- H Gupta
- Department of Diagnostic Imaging, Brown University School of Medicine, Rhode Island Hospital, Providence, USA
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