- Surgery is an important
part of cancer treatment and preoperative PET scan imaging is standard
diagnostic procedure nowadays
- PET scan detects cancer
nodules accurately in 90 percent cases but still has certain limitations
- New intraoperative
molecular imaging (IMI) using near infrared contrast found to improve
diagnosis of missed cancer nodules by making them glow
Combining preoperative PET
scan with intraoperative molecular imaging (IMI) could become a highly
effective method to increase diagnosis of very tiny 3 mm tumor nodules. It can
improve surgical outcome as well as patient prognosis, according to a recent
study conducted by scientists at the Abramson Cancer Center at the University of
Pennsylvania (ACC). The study findings have been published in Annals of
Imaging - What The ResearchTeam Has to Say
Cancer treatment and
diagnosis have advanced by leaps and bounds in the last two decades. Many
cancers are being diagnosed early by PET scan imaging and surgery remains one
of the mainstays of treatment.
‘Preoperative PET (positron emission tomography) scans combined with intraoperative molecular imaging prove to be highly effective in identifying tiny tumor nodules.’
In fact PET scan
imaging has a diagnostic
accuracy of 90 percent when it comes to cancer nodules. They do have certain
- PET scans are unable to
diagnose tumor nodules less than 1 cm
- Additionally, in some
cases, they cannot differentiate between cancer and benign inflammatory
- Most importantly,
preoperative PET scans do not always reflect the 'real-time' situation of
the patient's tumor during surgery which could have changed in the
The study team hoped to fill
in this gap and have successfully developed a new intraoperative intramolecular imaging (IMI) technique which when
combined with preoperative PET scanning significantly improved diagnostic
accuracy of cancer nodules.
Diagnostic Efficacy of PET Scan And IMI Combination In Identifying
For their study, the research team chose
50 patients undergoing surgery to remove lung nodules
to determine whether
preoperative PET scan and intra-operative IMI combined together, improved
diagnosis of cancer nodules.
- All of the patients had a pre-operative PET scan 30 days before
their procedure. These scans identified a total of 66 nodules.
- The team then conducted IMI
on these patients intraoperatively, using a near infrared contrast
agent dubbed OTL38 that makes tumor cells glow. Prior studies had found that IMI picks up cancer nodules
as tiny as 3 mm (or one-third the size of a shirt button).
- During surgery, IMI was able to correctly diagnose 60 of the 66
previously PET diagnosed nodules, or 91 percent. Additionally, IMI was
able to identify nine additional nodules that were undetected by the PET
scan or by traditional intraoperative monitoring.
- Overall, 75 nodules were identified between PET scan and IMI
- PET scan was accurate in determining cancer nodules in 51 patients
(68 percent). IMI was accurate in 68 nodules (91 percent)
- In patients evaluated in the above manner, adding IMI improved diagnosis by 30 percent. It also helped in
identifying cancer in about 10
percent patients that would have been normally missed on a CT or a PET
"Surgically removing tumors still leads to the best outcomes in
cancer patients, and this study shows intraoperative molecular imaging can
improve the surgeries themselves," said the study's lead author Jarrod D.
Predina, MD, MS, a post-doctoral research fellow in the Thoracic Surgery
Research Laboratory and the ACC's Center for Precision Surgery. "The more
we can improve surgeries, the better the outcomes for these patients will
Adds the study's senior author
Sunil Singhal, MD, the William Maul Measey Associate Professor in Surgical
Research and director of the ACC's Center for Precision Surgery,
"This shows the contrast agent is allowing us to remove more
cancer from the patient than we would have with PET imaging alone, especially
when we are looking at nodules 1 centimeter or smaller".
Emission Tomography (PET) Scanning
Positron emission tomography (PET) is a nuclear medicine functional
that is used to observe metabolic processes in the
body by studying the uptake of a
biologically active molecule such as fluoro deoxyglucose (FDG).
scanning has several medical applications including diagnosis of tumor and
metastasis and brain imaging to diagnose dementias among several others.
PET scanning is non-invasive
but patients are exposed to ionizing radiation.
of Current Study and Future Plans
Some of the takeaways and future plans based on the current study
include the following:
- It paves the way for future research involving OTL38 contrast
- This technology is now being tested in a formal, multi-center
clinical trial that will be the first Phase II study of molecular imaging
in the United States.
- The effectiveness of additional contrast agents, is
also being explored; some of the agents might be available in the clinical setting in a few months down
- These patients will also be followed up to find out if the
combined PET-IMI imaging improved surgeries and patient outlook. These
cancers can come back within five years in 25 to 30 percent of cases, and
the team hopes that their efforts reduce the incidence of recurrences.
In conclusion, should the results of this diagnostic modality be found
to significantly patient survival and surgical outcome, this could be a major
achievement and good news for doctors and patients worldwide.
- Positron emission tomography - (https://en.wikipedia.org/wiki/Positron_emission_tomography)