Assessment of lymph node metastasis esophageal cancer with SUV correction based on count recovery on 18F-FDG PET/CT

Objectives The aim of this study was to evaluate the diagnostic ability of standardized uptake values (SUV) on PET and size on CT in the assessment of lymph node (LN) metastases in patients with esophageal cancer, to evaluate the usefulness of partial volume effect correction for SUV using count recovery coefficients (RCs).

Methods To compute RCs, a NEMA image phantom containing FDG solution was imaged with the scanner. Thirty-five patients with confirmed esophageal cancer underwent PET/CT as a preoperative staging test. LNs of ≥5mm in diameter of which SUV max could be measured were included in the study. SUVmax of LNs was corrected for size with a RC method considering background SUV. Size on CT, SUVmax, and corrected SUVmax (cSUVmax) of LNs on PET/CT were correlated with histopathology, and analyzed with a ROC method to determine the diagnostic significance.

Results Sixty-eight LNs were included and histopathologically determined; 38 positive LNs (diameter of 11.0±5.1 mm, SUVmax of 4.0±2.9) and 30 negative LNs (8.0±1.8 mm, SUVmax of 1.7±0.4). To depict metastasis, the LN size on CT demonstrated the area under the ROC curve (Az) of 0.70 and cutoff value of 8.6 mm, while SUVmax and cSUVmax gave Az of 0.84 and. 0.82, cutoff of 2.00 and 2.15, respectively.

Conclusions Assessment with SUVmax and cSUVmax showed higher diagnostic ability for LN status than the size criteria alone on CT. However, SUVmax was slightly better than cSUVmax on this condition of scanner parameters.