such as "Introduction", "Conclusion"..etc
Like most treatments, laser therapy can benefit from image guidance. A
Houston-based company has developed an MRI-guided system that has been
tested and is now FDA-approved.
Laser induced thermal therapy (LITT) destroys unhealthy tissue, like
cancer, with the intense heat supplied from a laser. The laser light is
channeled through an optical fiber that can be inserted practically
anywhere in the body. One of the biggest challenges in LITT is that the
target cannot get too hot, otherwise it will char - thus preventing
further laser light from penetrating into the tissue.
To avoid this, physicians have traditionally measured the
temperature at some point near the target using a thermometer-like
probe. But real-time imaging could provide a non-invasive means to
monitor the temperature throughout the target region. In particular,
MRI provides a sensitive temperature probe. The frequency of the MRI
signal, which depends on the magnetic properties of water molecules,
shifts as the temperature of the corresponding tissue changes.
Using this effect, Visualase, Inc., has developed a closed-loop MRI
guided LITT system that provides the user with a temperature map of the
target region and calculates the corresponding dose (i.e. the
likelihood that cells in some region will die from the applied heat).
If nearby healthy tissue is receiving too much heat, or if the
temperature is approaching the charring temperature, the user can
respond by changing the laser power or shutting it off, which helps to
increase both the safety and efficacy of the procedure.
Trials of the system were independently performed on canines by R.
Jason Stafford from the University of Texas M.D. Anderson Cancer
Center, and his collaborators. Several LITT lesions were made in the
brain, spine and prostate with MRI guidance. The results showed that
the machine's calculated dose matched up well with a post-operation
assessment. Initial safety studies have also been performed in human
patients and the device has recently received FDA approval. Stafford
thinks MRI-guided LITT will provide a less invasive alternative to
conventional surgery. He is currently working to improve the real-time
targeting and heat delivery.
The research was described in the talk, "Closed-Loop Guidance of
Laser Induced Thermal Therapy Using MRI," presented July 31, 2008 at
the 50th meeting of the American Association of Physicists in Medicine.
Source : American Institute of Physics. August 2008.
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