Quantitative Findings of PET Indicate NHL Response
Patients with non-Hodgkins lymphoma (NHL) generally undergo positron emission tomography (PET) to determine response to treatment with chemotherapy. Response is determined with visual interpretation of scans. A new study from a French research team indicates that a quantitative index to evaluate scans provides additional information. Findings were published in the Journal of Nuclear Medicine.
Just over ninety patients participated in the trial, all had diffuse large B-cell lymphoma (DLBCL). Patients underwent PET imaging with F-FDG-PET scanning both before commencing chemotherapy and after receiving two cycles of treatment (midpoint of the regimen). The research team compared the standardized uptake value (SUV) to visual analysis of images.
Areas with the most intense levels of uptake had quantification of maximum SUV (SUVmax) and mean SUV (SUVmean), both values were normalized to body surface area and body weight. Tumor-to-normal ratios were also computed for those areas of intensity. These factors, as well as changes in those levels across time, were used to predict event-free survival (EFS) and overall survival. Findings with SUV data were compared to the visual assessments using ROC analysis and Kaplan-Meier curves for survival analysis.
The accuracy of PET findings using visual analysis to predict EFS was 65.2 percent. The two year estimate was 51 percent in the PET-positive group and 79 percent in the PET-negative group; this finding was highly statistically significant.
67.5 percent was determined as the optimal cutoff point based on ROC analysis. The two year EFS determined with quantitative PET was 21 percent in patients who had a SUVmax reduction less than 67.5; it was 79 percent among those with a SUVmax reduction greater than 67.5 percent.
The authors noted that quantitative assessment of PET scans provides clinicians with additional information about response to first-line chemotherapy in patients with NHL. This imaging modality provides visualization of metabolic activity and chemical function not captured with other imaging modalities.
October 31, 2007 Related topics: Imaging, Diagnostic, Radiology, Hematology & Oncology