Report from AMI: PET/CT attains slight edge over PET for lymphoma staging

March 23, 2005

PET/CT may boost physician confidence, but the fusion imaging technique is basically equivalent to PET alone for staging or restaging lymphoma.

PET/CT may boost physician confidence, but the fusion imaging technique is basically equivalent to PET alone for staging or restaging lymphoma.

Dr. Carina Mari Aparici, chief resident of nuclear medicine at Stanford University, came to this conclusion after evaluating the staging and restaging of Hodgkin's and non-Hodgkin's lymphoma for vatious cross-sectional modalities. She presented results from her study of 167 patients Tuesday at the Academy of Molecular Imaging meeting in Orlando.

Aparici found that PET/CT had a slight though statistically insignificant edge over PET alone. Radiologists interpreting the results correctly staged 92% of the cases based on PET/CT. For PET alone, accuracy was 90%.

The radionuclide procedures outperformed the protocols involving CT alone by a wide margin. Radiologists who read noncontrast CT scans were able to attain only a 42% accuracy rate. Only 27% of the cases were correctly staged when the radiologists based their findings on contrast-enhanced CT scans.

Overall, staging and restaging contributed to patient management changes in 117 cases. The PET/CT studies correctly led the reader to 99% of those recommendations. PET alone would have correctly pointed to 98% of the revised plans. Nonenhanced and contrast-enhanced CT would have led to correct calls in 45% and 2% of the cases, respectively.

The few differences between PET/CT and PET findings stemmed from PET's inability to identify retrocrural and costophrenic lymph nodes that changed the stage of a patient, Aparici said. PET/CT was more capable than PET alone at differentiating between brown fat and active lesions in two cases.

"Better staging leads to better treatment," Aparici said. Although the performance of PET/CT and PET was nearly identical, Aparici gave PET/CT an edge over PET alone because it offers the reader anatomic information that cannot be seen on PET images.

"We think it is going to improve the management of these patients," she said.