The first official document outlining the appropriate use of PET/CT in cancer patients, released in May, aims to help physicians and technologists follow standardized guidelines. But it's unlikely to quell the debate over who should interpret the hybrid exams.
Last year, a joint working group reached consensus on key issues related to training requirements for radiologists interpreting the PET portion of a PET/CT exam and for nuclear medicine physicians reading the CT component. But disagreements remain (Journal of Nuclear Medicine 2005;46[7]:1225-1239).
"Both sides are concerned about the ability of the other to become qualified in their specialty," said Dr. Lincoln L. Berland, president of the Society of Computed Body Tomography and Magnetic Resonance and a member of the joint working group.
For stakeholders, the impasse focuses on CT training rather than PET. Both sides have agreed on minimum requirements to interpret PET/CT (150 supervised PET/CT interpretations, 500 supervised CT interpretations), but they disagree on what can be interpreted under those conditions.
The American College of Radiology considers this training adequate for interpreting CT performed for anatomic localization, but not for interpreting CTs acquired for diagnostic purposes. The latter tests are medically indicated with a protocol optimized for the indication and billable charge. The SNM considers the training sufficient for interpreting CT studies regardless of protocol.
"A nuclear medicine physician should be able to interpret any CT done concurrently with PET. A CT is a CT. Increasing the current or giving contrast to the patient makes it easier to interpret, not more difficult," said Dr. Dominique Delbeke, lead author of the document, "Procedure guideline for tumor imaging with 18F-FDG PET/CT 1.0," published in the Journal of Nuclear Medicine in May.
The guidelines at least give nuclear medicine physicians some clout when approaching their local credentialing committee, said Delbeke, director of nuclear medicine and the PET Center at Vanderbilt University Medical Center. At many small hospitals that have mobile PET/CT scanners running once or twice a week, radiologists read the combined studies. If they are board certified, they are entitled to read PET. The converse is not true for nuclear physicians. Their board certification does not currently include diagnostic CT training, although it does address training in correlative imaging (CT, MRI, ultrasound, etc.).
"Right now, a radiologist-without any additional training-can interpret the combined PET/CT study. That is a disservice to the patient and to the technology," Delbeke said. "Both the nuclear medicine and the radiology communities agree on that point, and this is why PET/CT guidelines are necessary."
The ACR is developing a PET/CT guideline, but it will not be ready until 2007, said spokesperson Shawn Farley. The current guideline for performing and interpreting CT underwent a five-year review at the association's meeting in May, but no provisions had been added for PET/CT. Whether that changes in 2007 remains to be seen. But nuclear medicine proponents say it is time the ACR recognized PET/CT as a new type of imaging.
The existing ACR guidelines define CT by region of the body, such as brain, head and neck, chest, abdomen and pelvis, genitourinary, and musculoskeletal. PET/CT, and its corollary SPECT/CT, is a whole-body scan. CT training in body regions for nuclear physicians interpreting PET/CT does not make sense, Delbeke said. The ACR must devise a different concept for whole-body oncology CT, but making such a change requires time.
"I believe there will be more discussion and the situation will change," she said. "These guidelines are the first step in making necessary changes related to a new technology."
