Metabolic PET/CT guided lung lesion biopsies - impact on diagnostic accuracy and rate of sampling error

Abstract

CT-guided fine needle aspiration (FNA) of lung lesions is subject to sampling errors. Current study assesses whether information provided by FDG-PET/CT will decrease the false negative rate and thus improve the accuracy and of CT-guided FNA. Methods: Data of 311 consecutive patients with lung nodules who underwent FDG-PET/CT and CT-guided FNA within an interval of less than 30 days were retrospectively assessed. An in-house developed software co-registered CT images used to guide FNA (CT-FNA) with corresponding PET/CT data. The quality of registration was rated on a scale of 1(excellent) to 5 (mis-registration). Only cases scored 1-2 were further evaluated. The software provided the highest Standard Uptake Value (SUV) within the lesion and at the location of the tip of the aspirating needle. The distance (mm) between the tip and the area with the highest SUV within the lesion was measured. The mean distance from the tip of the needle to the focus with the highest SUV as well as the mean difference between the SUV_max in the whole lesion and at the needle tip were calculated and compared for cases with true positive (TP) and false negative (FN) FNA results. Anatomic and metabolic parameters of lesions included in these two groups were also compared. Results: There were 267 patients (86%) with score 1 and 2 registration quality of CT-FNA and CT-PET/CT images, including 179 TP studies (67%), 5 false positive (FP, 2%), 49 true negative (TN, 18%) and 34 FN (13%) FNA results. The distance between the location of the needle tip and the focus with the highest SUV in the lesion was significantly greater in the FN group (15.4 ±14mm) as compared to the TP group (5.9 ± 13.4mm, p<0.001). The SUV_max at the location of the aspirating needle tip were significantly higher in the TP group, 6.4 ± 6.4, as compared to the FN group, 4 ± 4.7, p<0.05. Conclusion: Present results demonstrate a relationship between the degree of metabolism at the site of tissue sampling aspiration in lung lesions and the accuracy of FNA results. Anatomo-metabolic based FNA guidance using information provided by both FDG-PET and CT may improve the accuracy of histological examinations, decrease the rate of FN results and thus increase the probability of achieving a definitive diagnosis.