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Thứ Sáu, 8 tháng 3, 2013

New Ultrasound Applications Detects Early Response to Pancreatic Cancer Therapy


New Ultrasound Applications Detects Early Response to Pancreatic Cancer Therapy

By Medimaging International staff writers
Posted on 06 Mar 2013

In a recent study, investigators utilized dynamic contrast enhanced-perfusion imaging (DCE-PI) and ultrasonic molecular imaging (USMI) to gauge response to therapy for pancreatic cancer.

The research was published in the January 2013 issue journal Technology in Cancer Research and Treatment. Paul Dayton, PhD, University of North Carolina (UNC) Lineberger Comprehensive Cancer Center (Chapel Hill, USA), and senior author of the study, said, “What we found is that using two noninvasive technologies, we can detect response to therapy earlier than by relying on tumor volume changes. Having new noninvasive, inexpensive technologies available to measure response to therapy earlier during the course of treatment would be a significant advance in the ability to tailor a person’s treatment to improve outcomes.”

Dr. Dayton, a UNC associate professor of biomedical engineering, worked with Jen Jen Yeh, M.D, an associate professor of surgery and pharmacology, to assess the imaging technologies on human pancreatic cancer in a preclinical model. Both investigators are members of the Lineberger Comprehensive Cancer Center.

USMI has the ability to depict noninvasively the biologic processes at the cellular and molecular levels. It accomplishes this with the use of targeted contrast agents, which are markers that bind to specific proteins expressed on cancer cells within the body. These contrast agents enable a conventional ultrasound system to identify signals from cancer cells that would otherwise be undetectable.

Ultrasound DCE-PI is a technique used noninvasively to track the blood flow in the microcirculation. Because growing tumors require abnormally increased blood flow, alterations in blood vessel structure or density can provide data regarding tumor malignancy. The researchers employed a drug that suppresses a protein specific to tumors. They then used the imaging applications to gauge the response of two different tumors, one known to respond to the drug therapy, and a second known not to respond. The findings indicated that USMI was able to detect molecular signs of tumor response to therapy after only two days.

A change in blood flow in the tumor was seen to detect response after day 14 using DCE-PI. Over the same period, standard volume measurements were not able to detect therapeutic response, and prior studies suggested that volume measurements do not become indicative of response until approximately 28 days. Therefore, these modalities revealed a substantial improvement in the early identification of tumor response to therapy, using contrast enhanced ultrasound imaging.

The contrast agents for USMI currently in clinical trials in Europe for cancer imaging, however, they are not yet available in the United States.
Related Links:
University of North Carolina Lineberger Comprehensive Cancer Center

Thứ Sáu, 1 tháng 3, 2013

Microbubbles improve myocardial remodelling after infarction

Microbubbles improve myocardial remodelling after infarction


Researchers at Bonn University Hospital demonstrate that ultrasound can ameliorate the sequelae of a myocardial infarction .



Scientists from the Bonn University Hospital successfully tested a method in mice allowing the morphological and functional sequelae of a myocardial infarction to be reduced. Tiny gas bubbles are made to oscillate within the heart via focused ultrasound - this improves microcirculation and decreases the size of the scar tissue. The results show that the mice, following myocardial infarction, have improved cardiac output as a result of this method, as compared to untreated animals. The study is now being presented in the professional journal PLOS ONE.





Every year in Germany, approximately 280,000 people suffer a myocardial infarction; more than 52,000 die as a result. Due to an occluded vessel, parts of the heart muscle no longer have sufficient circulation and the tissue dies off. These regions are not replaced by new heart muscle cells but instead by scar tissue – this generally causes the pump function of the heart to decrease following an infarction. Scientists from the Bonn University Hospital have now successfully tested a new method on mice with which scar tissue can be reduced and cardiac output increased.



Microbubbles are made to oscillate within the heart



“There are attempts to treat the scar tissue with gene therapy or stem cells - by contrast, we have chosen a physical approach to treatment,“ reports Adj. Professor Dr. med. Alexander Ghanem from the Department of Cardiology of the Bonn University Hospital. The researchers injected a total of 17 mice which had previously had a myocardial infarction with microscopically small, gas-filled bubbles in the bloodstream. Once the microbubbles reached the heart, they were made to vibrate there using focused ultrasound. “Through this mechanical stimulation, the circulation of the area of the infarction is improved - and the scar shrinks,“ says the cardiac specialist.



Treated animals demonstrate ameliorated post-infarction remodelling



The scientists compared the results of the mice treated with the microbubbles to those of a control group. Two weeks after the myocardial infarction, there was expected worsening of heart function in the control group due to the maturing of the scar tissue. In contrast, the mice treated with the microbubbles did not develop any cardiac insufficiency. Jonas Dörner, the first author of the study, summarizes the results: “The pumping function was significantly better in the treated animals as compared to the control group; there was also a significantly smaller amount of decayed heart muscle tissue.” Along with the Department of Cardiology, the Departments of Cardiac Surgery and Anesthesiology and the Institute of Physiology took part in the investigations.



Ultrasound treatment stimulates growth hormones



The scientists sought the causes of the positive treatment success which is, however, unexplained to date. Following ultrasound treatment of the mice, it was demonstrated that the amount of the body’s own growth hormones significantly increased in the heart. “This is evidently the reason why the scar formation decreased as a result of the oscillating microbubbles,“ says Dr. Ghanem. The scientists now hope that humans will also be able to eventually be treated with the microbubble-ultrasound method, however further investigations are still needed. “Potentially, all patients who have had an acute myocardial infarction are eligible for this follow-up treatment,“ explains the cardiologist of the Bonn University Hospital. Interestingly, microbubbles are already used as a diagnostic contrast agent.



Patent for novel ultrasound method filed



The study, conducted with support from the BONFOR funding program of the Medical Faculty of Bonn University and the German Heart Foundation [Deutsche Herzstiftung e.V.], gave rise to a patent application. “Together with the company Philips Medical, we developed a novel ultrasonic probe which enables a standardized impulse discharge in the heart,“ reports the cardiologist. The special feature is that two ultrasound sources linked together are contained in one hybrid ultrasonic probe: one with low frequency for the focused stimulation of the microbubbles in the target organ and one with higher frequency for imaging. In this way, it can be very precisely determined where the scar tissue and the microbubbles are located. “This study demonstrates again that university research inspires technological developments in medicine,“ says Dr. Ghanem.



Publication: Ultrasound-mediated stimulation of microbubbles after acute myocardial infarction and reperfusion ameliorates left-ventricular remodelling in mice via improvement of borderzone vascularisation, PLOS ONE, DOI: 10.1371/journal.pone.0056841, Internet: Internet