PET Scans Used To
Detect HIV Progression

By Patricia Reaney

LONDON (Reuters) - A scanning technique can track the progression of HIV and could lead to new treatment options and the development of the next generation of anti-AIDS drugs, scientists said on Friday.
Positron emission tomography (PET) scans are usually used to identify cancerous tumors, but researchers in the United States believe the technology could play an important role in the battle against AIDS by identifying the impact of the virus on lymph nodes which could be treated with radiotherapy or surgery.
Dr C. David Pauza and scientists at the University of Maryland Biotechnology Institute in Baltimore Maryland took whole body PET scans of 15 HIV patients and found fairly distinct sites of immune response during different stages of the illness.
"We believe that if we identify those sites clearly during HIV infection we encourage people to consider these types of interventions," Pauza said in an interview, referring to surgery or radiotherapy.
During early disease, lymph nodes in the head and neck were activated, according to the PET scans, but in later stages the virus stimulated an immune response in areas of the torso and later in the bowel.
HIV/AIDS is treated with antiretroviral drugs. Surgery or radiotherapy would open up a new approach to the illness that has affected 42 million people worldwide.
"We are not aware that it has ever been tried," said Pauza, who reported his findings in The Lancet medical journal.
"We think it is appropriate to consider these approaches and also appropriate to learn from the cancer models because cancer is a disease of chronic cell activation and growth and in some ways, even though HIV is triggered by a virus, it has some similarities," he added.
In cancer patients, PET scans measure the activity of cancerous cells, while in HIV it picks up levels of immune system reaction.
David Schwartz and Sujatha Iyengar, of the Johns Hopkins University Bloomberg School of Hygiene and Public Health who also used PET scans to track HIV progression, said lymph node removal could give patients an opportunity for a break in antiretroviral treatment.
"Although many systemic sites from which latent virus could be re-activated would be left, re-activation might not occur for months or years after removal of the active nodes, thereby allowing extended interruption of treatment," Schwartz said in a separate study published in The Lancet.
Pauza also suggested that with the pattern of progression detected with the PET scans it could be possible to develop a prognostic tool for HIV, new drugs for patients in whom existing therapies have failed, or other illnesses.
"One thing we discovered as we were going through this work is that there was a substantial amount of undiagnosed cancer associated with HIV. We observed a number of patients with lymphoma," he added.
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