SAN FRANCISCOA highly sensitive photon sensor has
shown promise as a means of detecting early, subtle responses to neoadjuvant
therapy among patients with soft tissue sarcomas, investigators from the
Dana-Farber Cancer Institute reported at the 37th Annual Meeting of the
American Society of Clinical Oncology (ASCO).
The new modality, known as dynamic infrared imaging (or DIRI),
is based on infrared-detection technology developed for the "Star
Wars" missile defense system (see box).
Sarcomas often present with complex morphology that is
difficult to evaluate on CT or MRI, said presenter Milos Janicek, MD, PhD.
Dynamic infrared imaging, he said, "is a very sensitive, rapid, and
precise method" of monitoring infrared emission data from the tumor site
or adjacent soft tissues that can show changes in blood perfusion. He noted
that the prognostic significance of metabolic and perfusion changes in sarcomas
"is very intriguing."
The Dana-Farber researchers are using the BioScan System
(OmniCorder Technologies, Stony Brook, NY), which consists of a digital
infrared camera that "counts" photons (electromagnetic radiation)
emitted from tissues and organs, and sophisticated computer software that
analyzes changes in the photon flux to map patterns of blood perfusion in
tissues (see Figure 1). The results can be viewed on a monitor or
printed out as hard copy.
The device has been cleared for marketing by the FDA for use as
adjunct diagnostic screening for detection of breast cancer and diseases
affecting the blood perfusion or reperfusion of tissue or organs.
How It Works
Cancer cells produce a variety of vasoactive substances such as
nitrous oxide, which lead to increased blood flow in tissues surrounding the
cancer. The sensor detects the infrared energy (photons) emitted from the body,
thus "seeing" the minute changes in tissue blood perfusion or
reperfusion caused by cancer metabolic activity.
Production of vasoactive substances and tissue mediators begins
earlier than measurable mass, which is detected by
x-ray or CT.
The BioScan System is sensitive to changes in infrared photon
flux that are equivalent to temperature changes of less than .009 of a degree
centigrade and has a speed of more than 200 frames per second. A typical
digital infrared exam takes about 20 seconds.
George Demetri, MD, medical director of the Center for Sarcoma
and Bone Oncology at Dana-Farber, and one of the study authors, said that
infrared imaging may be particularly useful in measuring responses to new
antiangiogenesis agents under study. Because of its safety, speed, and low
cost, dynamic infrared imaging can be performed frequently in studies of new
Dr. Janicek suggested that antiangiogenic effects are not
specific to so-called antiangiogenic agents, but, rather, may be common to
large groups of therapies that may have a toxic effect on the newly formed
blood vessels. "Here, digital infrared imaging might make a powerful
contribution due to its ability to monitor perfusion-related changes linked to
tissue physiology and cell growth or death," he said.
Dr. Demetri stressed that the technique documents blood vessel
oscillations, as opposed to simply heat. "Our normal blood vessels are
oscillating up and down in a certain way, and it turns out that tumor blood
vessels go through that rhythm in a very confused and very different way,
registering a very different pattern that can be seen with digital infrared
imaging," Dr. Demetri said. "It has nothing to do with temperature.
The temperature of two parts of the body might be exactly the same, but the
pattern of oscillation is very different."
The Dana-Farber researchers performed 27 sets of CT scans,
FDG-glucose PET scans, and digital infrared images (at baseline and at 1-month
intervals) in 14 patients with soft tissue sarcomas receiving a variety of drug
treatments. On digital infrared imaging, tumor masses were identified as areas
of increased heat distribution and increased modulation (or oscillation) of
temperature (blood vessel oscillations).
Sarcomas were selected for the study, many of them large but
often relatively superficial. It was assumed that lesions relatively close to
the surface of the body would be more likely to register changes on infrared
Visual examination of digital infrared images correctly
suggested clinical progression or regression of tumors after treatment in 75%
of lesions, Dr. Janicek said. "For those tumors that responded to
treatment, there was decreasing temperature modulation between baseline and
rescanning 1 month later, whereas progressive tumors showed statistically
significant increases in modulation," he said (see Figure 2).
Dr. Janicek noted that baseline temperature did not predict
response. "All tumors show similar warmer temperature, compared with
background," he said. Temperature modulation, however, may have prognostic
potential, since baseline modulation was greater for those tumors that
subsequently responded to treatment, he said (see Figure 3).
Long Follow-up Planned
He concluded that infrared imaging could add information on the
biology of the tumor. "It monitors tumors with a noninvasive,
easy-to-reproduce approach, provides both quantitative and qualitative
assessment, and may even have predictive value at baseline, allowing for
selection of patients," Dr. Janicek said.
He noted that patients will be followed for several years in
order to correlate the prognostic information from the infrared images with
The discussant for the sarcoma session, Douglas L. Fraker, MD,
University of Pennsylvania, called the new technique "an important way to
look at tumors."
Instead of giving neoadjuvant therapy and seeing if patients
respond, Dr. Fraker said, physicians might be able to predict a response by
looking at the temperature modulation in the tumor before treatment. Another
method to accomplish this may be by looking at tumor hypoxia, he commented.
In an interview, Mark Fauci, MBA, president and CEO of
OmniCorder, said that the BioScan System is being tested in a variety of other
settings, including use during brain surgery to "see" blood perfusion
changes around the margins of brain lesions and in response to stimulus of
different areas of the brain.
Overcoming ‘Brain Shift’
At the Mayo Clinic, Rochester, Minnesota, he said, surgeons are
investigating digital infrared imaging as a means of overcoming the problem of
"brain shift" during lengthy surgeries. Once the skull is opened, the
brain and thus the location of the tumor may shift by centimeters, rendering
the preoperative MRI data on tumor location imprecise, he said.
"The bottom line," Mr. Fauci said, "is that
cancer therapy monitoring is only one of many applications that we’re working