Imagine a new world of detecting and diagnosing diseases sooner—even before any symptoms are present. Consider the possibility of receiving individualized, targeted molecular, cellular or genetic medical treatment as soon as possible and of undergoing scanning that can quickly tell your doctor whether your treatment is working. Continued advances in positron emission tomography (PET) imaging are key to this future, according to Simon R. Cherry, professor of biomedical engineering at the University of California, Davis.
"Earlier detection of diseases and of the effect of treatment on them is the main impetus in advancing PET technology," says Cherry, who offered predictions about PET's growing importance in the November issue of the Journal of Nuclear Medicine.
In the far future, individuals may be able to take a simple—as yet undeveloped—annual blood and/or urine test to screen protein or metabolite levels that could indicate common diseases, said the author of "The 2006 Henry N. Wagner Lecture: Of Mice and Men (and Positrons)—Advances in PET Imaging Technology." Since nearly all diseases alter the body's biochemical processes, "this type of test could allow a doctor to compare a patient's results with those from previous years and flag a beginning disease process," added the director of the UC Davis Center for Molecular and Genomic Imaging.
"Once a change is noted, it will be critical to localize and visualize the disease and monitor how it responds to therapy. This is where PET technology offers powerful opportunities," he said. With PET's molecular imaging ability—the ability to "photograph" biological targets or pathways—doctors will be able to detect molecular changes that could provide valuable information about treating and even preventing the onset of Alzheimer's or other brain disorders, cancers and heart disease. "PET's diagnostic ability in the future will tell us something about the precise molecular makeup of disease in a specific person," added Cherry, who originally presented his technological predictions at this past June's annual meeting of SNM, the largest organization dedicated to the practice, science and technology of molecular imaging and therapy and nuclear medicine.
PET imaging is an invaluable way to gather medical information that would otherwise be unavailable, require surgery or necessitate more expensive diagnostic tests. It is used today to effectively point to many of the most common cancers, heart diseases and neurological diseases using positron-emitting radiopharmaceuticals in patients and tracking the activity distribution with a special camera. While the PET scanner measures the location of radioactive substances in the body, a computer translates the information into images.
"Major advances in technology have clearly improved image quality, increased the range of clinical applications and contributed to more widespread use of PET," noted Cherry. "We will continue to see major advances and improvements in PET technology for some time to come," he predicted. In addition, PET will continue to help researchers bridge or "translate" research on drugs from initial studies with animals through to clinical trials with people.
While the outside appearance of PET scanners may not have changed much over the past 15 years, there has been a revolution in its technologies and methods, said Cherry. Major advances in PET include the use of whole-body imaging, three-dimensional imaging, new scintillator materials, iterative reconstruction algorithms, combined PET/computed tomography (CT) imaging and preclinical PET.
Cherry foresees that additional advances will come with
Looking ahead, Cherry envisions that integrating whole-body PET with MRI could revolutionize the profession, possibly offering significant diagnostic benefits. "Patients could benefit greatly from harnessing the combination of these two powerful technologies," said Cherry. The future of PET/MRI is on hold until researchers master the technological complexity of combining PET detectors with relatively high magnetic fields and overcome economic considerations (this technique will initially be expensive in a financially restricted health care setting).
"The 2006 Henry N. Wagner Lecture: Of Mice and Men (and Positrons)—Advances in PET Imaging Technology" appears in the November issue of the Journal of Nuclear Medicine, which is published by SNM, an international scientific and professional organization of more than 16,000 physician, technologist and scientist members. For more information, please visit SNM's Web site at http://www.snm.org.
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