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Oncology-Clinical Diagnosis: Solid TumorsClinical Diagnosis-Solid Tumors Posters |
1 Department of PET; 2 Department of Diagnostic Radiology, Kinki University School of Medicine, Osaka-Sayama, Osaka, Japan
1532
Objectives: In FDG PET/CT studies, standardized uptake values (SUV) tend to be underestimated for small lesions due to the partial volume. The purpose of this study was to evaluate the impact of a correction method using count recovery coefficients (RCs) on maximum SUV (SUVmax) in the assessment of lymph node (LN) metastasis in lung cancer.
Methods: To compute RCs, an image phantom containing FDG solution was imaged with the scanner. Thirty-two patients with confirmed lung cancer underwent PET/CT as a preoperative staging test and then surgical resection. LNs of 
10 mm in diameter on CT of which SUVmax could be measured were assessed in the study. SUVmax of LNs was corrected for the size with a RC method. 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: Forty-six hilar and mediastinal LNs were included and histopathologically confirmed:21 positive LNs (diameter:15.3±4.2 mm, SUVmax:4.9±2.7) and 25 negative LNs (diameter:12.5±2.6 mm, SUVmax:2.0±0.5). In the discrimination of LN metastasis, the LN size on CT demonstrated the area under the ROC curve (Az) of 0.70 and cutoff of 13 mm, while SUVmax and cSUVmax gave Az of 0.94 and 0.89, cutoff of 2.84 and 2.48. All 6 falsely negative LNs on CT were correctly diagnosed as positive with either SUVmax or cSUVmax.
Conclusions: Assessment with SUVmax and cSUVmax showed better diagnostic accuracy for LN status as compared to the size criteria alone on CT. The partial volume correction enhanced low SUVmax in smaller lesions and made it more recognizable.
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