Two studies on Naviscan high-resolution breast PET scanner

The American Journal of Roentgenology published original research from two separate studies this month demonstrating continued clinical acceptance of  the Naviscan high-resolution breast PET scanner, otherwise known as a PEM scanner.  The first study concluded that breast radiologists can achieve a high level of diagnostic performance in interpreting PEM images after a 2-hour tutorial which can take months to achieve with MRI.  The second study established a standard lexicon for the evaluation of PEM images making it simple to share a diagnosis.

PEM scanners are high-resolution breast PET systems that can show the location as well as the metabolic phase of a lesion. This information is critical in determining whether a lesion is malignant and influences the course of treatment.  With increasing use of PEM imaging, there is a need for standardized terminology to describe findings seen on PEM, interpretation, and management recommendations, similar to the standardized classification that exists for other breast imaging modalities.  

The purpose of the interpretative skills study was to prospectively validate how easy it is to learn and standardize the interpretation of PEM by breast radiologists.  Thirty-six observers from 15 sites throughout the United States completed both PEM and MRI interpretive skills tasks.  All participants underwent a 2-hour training program for interpreting PEM images.  The median sensitivity and specificity for PEM assessment tasks were 100% and 83% respectively, compared to the median sensitively and specificity of MRI at 82% and 69% respectively. The results indicate that, with minimal training, experienced breast imagers showed high performance in interpreting PEM images.

"PEM interpretation is relatively simple," stated Dr. Priscilla Slanetz, Director of Breast Imaging Research and Education at Beth Israel Deaconess Medical Center, a participant in the study.  "Assessing for areas of focal uptake typically is straightforward and takes just 1-3 minutes at most. In comparison, interpreting breast MR can take anywhere between 5-20 minutes, depending upon the complexity of the case and the number of sequences acquired."

Complementing this study, the lexicon paper outlines a standardized terminology to report PEM findings, similar to the BI-RADS developed through the American College of Radiology used extensively for mammography, ultrasound, and breast MRI.  Twenty investigators reviewed 404 malignancies in 388 patients in the development of the PEM lexicon.  The most interesting finding was that category 3, "probably benign," had a substantially higher rate of malignancy when compared to other modalities demonstrating how PEM is more accurate and decisive at differentiating between malignant and benign lesions in what is called "specificity."  Ultimately, PEM's high specificity has been suggested to be able to reduce unnecessary biopsies.