SESSION TITLE: Imaging Posters
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 28, 2015 at 01:30 PM - 02:30 PM
PURPOSE: Integrated Positron Emission Tomography/Computed Tomography (PET-CT) is a well-validated modality for assessing pulmonary mass lesions and specifically for estimating the risk of malignancy. Tuberculosis (TB) is known to cause false positive PET-CT findings. We aimed to investigate the utility of PET-CT in the evaluation of pulmonary mass lesions and nodules in a high TB prevalence setting.
METHODS: All patients referred for the evaluation of an apparent solitary pulmonary nodule or mass and who underwent PET-CT scanning over a 3-year period were included. The PET-CT findings, including maximum standardized uptake value (SUVmax), were compared to the gold standard (tissue or microbiological diagnosis). The sensitivity, specificity, positive and negative predictive values and diagnostic accuracy for malignant disease were calculated according the SUVmax cut-off of 2.5 and according to a proposed cut-off value obtained from a ROC curve.
RESULTS: Forty-nine patients (60.1+/-10.2 years, 29 males) were included, of whom 30 had malignancy. Using an SUVmax cut-off of 2.5, PET-CT had a sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy for malignancy 93.3%, 36.8%, 70.0%, 77.8% and 71.4% respectively. After a ROC curve analysis, a suggested SUVmax cut-off of 5.0 improved the specificity to 78.9% and the diagnostic accuracy to 86.7%, with only a small reduction in sensitivity to 90.0%.
CONCLUSIONS: The diagnostic accuracy of PET-CT in the evaluation of pulmonary mass lesions using the conventional SUVmax cut-off of 2.5 was reduced in a TB endemic area. An SUVmax cut-off of 5.0 has a higher specificity and diagnostic accuracy for malignancy, with a comparable sensitivity.
CLINICAL IMPLICATIONS: The reduced specificity for malignancy of PET-CT in TB endemic areas can be significantly improved by using an optimised threshold for SUVmax. PET-CT is still a valuable adjunct in the assessment of patients with a pulmonary mass lesion on presentation, provided other clinical and radiological evidence are integrated in the assessment. Further research on integrating various SUVs with clinical and radiological prediction scores in high TB prevalence settings is needed.
DISCLOSURE: The following authors have nothing to disclose: Coenraad Koegelenberg, Rudolf du Toit, Jane Shaw, Florian von Groote-Bidlingmaier, James Warwick, Elvis Irusen
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