Tuesday, January 29, 2008

Stroke Treatment

I have been very interested in the recent advances in targeted therapy using ultrasound contrast agents (bubble technology). It has been known for a few years that micro bubbles filled with gas can be safely administered IV to image many organs in the body using conventional sonography and harmonic imaging.
The idea of filling these bubbles with other medications along with the gas, and adding proteins to allow the bubbles to target specific tumors or clots is not new, and research continues along these lines. I am hopeful that in the near future, Sonographers may be intimately involved in treatment as well as diagnosis of conditions likely to respond to this form of targeted delivery.
As an American, I am very disturbed by the FDA's decision to black box Definity and Optison; agents used to opacify the heart for wall motion abnormalities. In the EU, ultrasound contrast has been safely used for years for evaluating liver lesions, trauma, echocardiography, and vascular imaging. Contrast is only approved in the USA for LVO (left ventricular opacification). I find this extremely disturbing. Many cardiologists are protesting this black box warning because of flawed evidence concerning a very minor number of events where contrast was a party to the treatment or evaluation of the patient.
I register this protest because the potential life saving benefits that ultrasound contrast has to offer outweighs the potential negative side effects. The FDA has made a very poor case regarding the black box warning, and the ultrasound community is responding. The potential future benefits of contrast in the ED, and in routine imaging are limitless in my opinion.
Uses in the EU include:
* Trauma and organ damage with bleeding due to trauma
* Ischemia to almost any organ
* Perfusion surveillance (kidney transplants, etc)
* Torsed testicles or ovaries
* Lesion categorization in the liver and other organs
* Differentiation of clot from living tissue/tumor
These are routine uses in the EU. Why the hell is the USA balking at adding contrast to our vast arsenal of life saving drugs? My guess is political and financial manipulations. It is always about the money.
Here is an interesting discussion about one companies struggle to produce an agent with potential to treat stroke patients:
ImaRx Therapeutics, Inc. recently issued a progress report on its TUCSON (Transcranial Ultrasound in Clinical SONoLysis) United States Food and Drug Administration clinical trial involving patients with acute ischemic stroke. TUCSON is a randomized, placebo controlled clinical trial to evaluate the safety, tolerability and effectiveness of a ImaRx’s microbubble-based agent MRX-801. Administration of MRX-801 and ultrasound imaging is being used as an adjunctive therapy to the conventional method of administration of tissue plasminogen activator (tPA) for treatment of two different cohorts of patients with acute ischemic stroke.
Take care,
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