Aiming for the ideal: Standardizing cancer FDG PET/CT imaging

Now that hybrid PET/CT systems are thoroughly mainstream, standardization of practice has moved into the spotlight. A thorough F-18 FDG PET/CT oncological report should include much more than just what meets the eye, according to the authors of a comprehensive review published in the May issue of The Journal of Nuclear Medicine.

Ryan D. Niederkohr, MD, senior physician at Kaiser Permanente Medical Center in Santa Clara, Calif., and colleagues, outlined a blow-by-blow of the fine print that should be included in every F-18 FDG PET/CT imaging study.

The authors estimated that the number of PET/CT systems in the U.S. has spiked from about 200 scanners in 2001 to more than 2,000 in 2010. The number of PET examinations performed also swelled over seven times what it was in 2001 from approximately 250,000 scans to more than 1.7 million in less than a decade.

“At some institutions, PET/CT is now the most frequently performed nuclear medicine imaging study, surpassing myocardial perfusion imaging among others,” wrote Niederkohr et al. “This dramatic increase in PET/CT volume highlights the growing clinical acceptance and importance of hybrid anatomic and functional imaging.”

PET/CT cancer screening with F-18 FDG has become an important tool in the oncologist’s arsenal. This research was conducted to optimize the benefits and avoid the pitfalls of sparse reporting and confusing terminology.

“The interpretative report rendered by an imaging physician is the only tangible manifestation of the physician’s expertise,” wrote the authors. “The content of this report not only influences patient management and clinical outcomes but also serves as legal documentation of services provided. To ensure that PET/CT reports are consistently of high quality, we suggest that institutions standardize the structure and language of their reports, taking into consideration the essential elements discussed in this paper.”

These elements included essential information that was noted as missing from more than 40 percent of reports--study indication, time of tracer injection, patient treatment history and comparative detail regarding past imaging studies. Clinical histories should include tumor type and location and a summary of treatment, both previous and ongoing, including surgeries, radiation treatments or cycles of chemotherapy. Referring physicians’ clinical questions should be clearly stated, using language that complies with regulatory bodies such as the Centers for Medicare and Medicaid Services, which tends to respond best to reports that define initial treatment strategies and updates as that strategy changes.

Radiotracer usage should be outlined with the radiopharmaceutical's name, administration information including method of administration, precise dosage, route of administration, timing in relation to scanning and uptake data. Recommended guidelines from several organizations such as SNMMI, EANM and ACR suggest testing and reporting blood glucose levels. 

The CT technique used should be included, especially whether the CT component was optimized using full tube current with intravenous or oral contrast or by comparison if CT was used only for attenuation correction or structural localization using a low radiation dose method or without contrast. Any adverse reactions should be specified in the report indicating symptoms and subsequent treatment. Any unorthodox or investigational methods should be detailed in the report.

Readers should look for and compare current imaging studies with prior studies and reports. This includes not only previous PET and PET/CT studies but also CT and MR scans. “Results in the literature have shown that comparison with prior imaging improves diagnostic accuracy,” explained the researchers.

Findings of any oncological FDG PET/CT study should start with positive or negative PET indications that immediately address the clinical question at hand and the most prominent presentation of disease, followed by relevant CT indications.

Researchers noted that the impression is perhaps the most important piece of the puzzle and that referring physicians often lead with their impression followed by PET/CT findings. This study recommended that all impressions be both succinct and comprehensive.

“The impression should allow the reader to clearly identify whether the PET/CT findings are normal or abnormal, and it should answer the specific clinical questions raised by the referring physician,” noted the authors. “The impression should provide a clear diagnosis or a brief list of differential diagnoses with level of likelihood.”

One thing that many imaging professionals may not know is that an increasing number of institutions allow patients full access to imaging reports, making it salient to avoid any unnecessarily hyperbolic language, “(e.g., dramatic increase or too numerous to count), which is generally unhelpful and might provoke unnecessary patient anxiety,” added the researchers.