SESSION TYPE: Imaging Posters
PRESENTED ON: Wednesday, October 24, 2012 at 01:30 PM - 02:30 PM
PURPOSE: We explored the role of dual-time point FDG-PET-CT (DTP PET/CT) scan in the differentiation of benign and malignant lung and mediastinal lesions in our area, which is endemic for histoplasmosis and has a high prevalence of sarcoidosis.
METHODS: We studied a sample of 72 consecutive patients who underwent DTP PET/CT scan for intrathoracic lesions. Information was collected on demographics, initial and delayed SUV max values of lesions, final diagnosis and the modalities with which the diagnosis was made. Clinical criteria to diagnose benign lesions were defined as stability or regression of the lesion on follow up after two years of initial detection. Sensitivity, specificity, predictive values and likelihood ratio and retention index were calculated using standard methods.
RESULTS: Of the 72 patients who underwent DTP PET/CT, 63 (87%) had increased in SUV uptake in delayed scan at one hour after initial scan (delayed). Among the patients with increased delayed uptake, 51 (80%) had malignant lesion and 12 (20%) had non-malignant lesions. Of the remaining 9 patients whose SUV max decreased on delayed scan, all of them had non-malignant lesions. The increased SUV on delayed scan was 100% sensitive in diagnosis of cancer but was only 42% specific. The positive predictive value was 80% whereas the negative predictive value was 100%. Likelihood ratio for positive test was 1.75.
CONCLUSIONS: All the lesions with decreased SUV max in delayed PET scan were non-malignant. This was true for both lung and mediastinal lesions. This could be a very helpful diagnostic finding in areas with high prevalence of benign conditions such as histoplasmosis and sarcoidosis. Multiple invasive diagnostic modalities could be prevented in a significant percentage of patients, with attendant decrease in morbidity, as well as health care costs.
CLINICAL IMPLICATIONS: With its high sensitivity for malignancy and high negative predictive value, DTP PET/CT can provide important information on the need and extent of further evaluation and treatment in patients presenting with intrathoracic lesions.
DISCLOSURE: The following authors have nothing to disclose: Dipen Kadaria, David Archie, Amado Freire, Muhammad Zaman
No Product/Research Disclosure InformationUniversity of Tennessee HSC, Memphis, TN