Another Imaging Agent to be Submitted to FDA

Authors make the case for  68Ga DOTATOC PET/CT 

The September issue of the Journal of Nuclear Medicine features a research study and perspective article in support of an application to the Food and Drug Administration (FDA) for approval of  68Ga DOTATOC PET/CT, another new imaging agent to assess NETs in scans. Authors found 68Ga DOTATOC superior to decades-old methods for disease staging, treatment planning, and identifying unknown primary sites.

The study, however, did not compare 68Ga DOTATOC  to 68Ga DOTATATE, which was approved by FDA in June 2016.  An application for 68Ga DOTATOC would ask FDA to approve an additional imaging agent for NETs.

Advocacy for expanding options in imaging

Josh Mailman, a member of NETRF Board of Directors, and President, NorCal CarciNET Community, wrote an invited perspective introducing a meta-analysis of 68Ga DOTATOC by Dr. Michael Graham. Josh first underwent a PET/CT scan with 68Ga DOTATOC in 2008 in Europe (where it is was available). “DOTATOC and other targeted peptides will give clinicians new tools to work with in the management of NET patients,” wrote Mailman. “More tools will continue to increase access for patients to undergo diagnostic imaging and improved outcomes.”

68Ga-Dotatoc PET/CT exam of a neuroendocrine tumor; in the CT alone (top) there is no indicator for any lesion

68Ga DOTATOC is one of a few imaging agents that help radiologists “see” NETs on PET/CT scans.  It is injected in advance of a patient’s scan so it can bind to tumor receptors. Many of the typical imaging agents used in PET/CT scans don’t work with NETs.

A deep dive into data

Lead investigator Michael Graham, M.D., Ph.D., and colleagues in the Division of Nuclear Medicine, Department of Radiology, University of Iowa, evaluated published data on 68Ga-DOTATOC to see if it was more effective than 111In-octreotide, which has been used for more than two decades. Their search of medical journals identified 468 articles, which they narrowed down to 17 studies. Graham then analyzed the findings of each study to see if they came to similar conclusions.

Graham found alignment among the 17  studies. “The results that have been reported are remarkably consistent and there is little question that this agent is safe, effective, and more accurate than 111In-octreotide, the standard for the past 22 years,” he wrote.

Significant benefits identified

Graham’s analysis found 68Ga-DOTATOC effective in multiple ways:

  • Accurately detecting NETs when they are there (and not detecting them when they were not there, also called false positive results) (overall sensitivity and specificity of 93%)
  • Detecting an unknown primary tumor site in patients with extensive metastatic disease (overall success rate of 44%)
  • Helping tailor treatment to an individual’s disease (51% of doctors changed patients’ treatment plans based on test results)

Data showed 68Ga-DOTATOC to be less effective in identifying NETs in unusual/complex cases, when the diagnosis of NETs had not been established, or when other tests were inconclusive. Many of the studies included in Graham’s analysis were conducted outside the U.S. The studies analyzed were published between 2001 and 2015.

68Ga-DOTATOC also offers improved convenience for patients. It takes considerably less time, only a few hours, compared to a few days for 111In-octreotide. In addition, it does not require the use of laxatives.

Both Graham and Mailman concluded,  “68Ga-DOTATOC appears to be an excellent imaging agent to assess patients with a known NET and frequently leads to a change in management.” The University of Iowa is expected to submit an application to FDA for approval.

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I had a Gallium 68 Scan and it didn’t show any more than a CT scan. The doctor also explained you cannot measure the carcinoid size on a Gallium 68 because the image is blurry due to the carcinoid putting out too much energy. What are the benefits of using the Gallium 68 over a CT if you cannot measure the carcinoid image or is my understanding incorrect?

Josh’s response is spot-on. The CT scan alone cannot tell if a lesion is a NET or another type of tumor. The Octreoscan has been the “gold standard” for distinguishing a NET from a non-NET lesion. Now, there’s a more sensitive NET imaging tool, the Ga68 scan…it’s approximately 10 times as sensitive as the Octreo Scan in detecting NET’s. It’s true that one also needs the CT imaging to accurately measure the size of lesions; the CT’s edge detection is more precise than that of a nuclear image.

For a great percentage of those with NETs Ga68 Dotaxxx imaging will result in more information than previously shown with prior imaging. That being said there is no one perfect scan and you will need to work with your doctor, radiology and nuclear medicine departments to determine the best imaging routine for your particular case. You may wish to view the following video from Dr. Tom Hope on imaging for NETS that goes into great detail with examples from the SNMMI 2017 patient education day in Denver. As the Iowa data suggests and other centers around the world have… Read more »


I have had two net spot scans that showed activity. I get an injection shot every 28 days. What else should the doctor be ordering?

Another Imaging Agent to be Submitted to FDA