Dual-phase FDG-PET: delayed acquisition improves hepatic detectability of pathological uptake

Abstract

Acquisition of delayed images improved the hepatic detection of pathological FDG uptake.

Use of Dual-Point Fluorodeoxyglucose Imaging to Enhance Sensitivity and Specificity

“…57 In a series of 95 consecutive patients previously treated for neoplastic disease and with suspected liver metastases, a DP PET/CT was acquired (1 and 2 hours after FDG injection). Thirty-seven of 95 patients (38.9%) presented liver lesions at both PET/CT scans, whereas there were 2 (2.2%) only at the second PET/CT.…”

Detection of Hepatic Metastases Using Dual-Time-Point FDG PET/CT Scans in Patients with Colorectal Cancer

“…Recently, there have been several attempts to enhance the detection rate of malignant lesions with dual-time-point FDG PET scans [13][14][15][16][17][18][19][20][21][22][23][24]. According to previous studies, tumor tissue shows gradual accumulation of FDG, suggesting that the contrast between tumor and normal background tissue on delayed PET imaging could be higher than that on routine PET imaging [13,14,25].…”

“…Based on this characteristic of malignant lesions, dual-time-point FDG PET imaging demonstrated improved tumor detection in patients with lung cancer [15], breast cancer [16], gallbladder carcinoma [17], and thymic tumor [18]. Furthermore, there have been several studies to improve the detection of liver tumors using a dual-time-point PET scan [19][20][21][22][23][24], suggesting that a dualtime-point PET scan was useful for the detection of hepatic metastases. However, it is not clear which parameter of a dual-time-point scan is the most useful for the clinical identification of hepatic metastases.…”

Accuracy of early and delayed FDG PET-CT and of contrast-enhanced CT in the evaluation of lung nodules: a preliminary study on 30 patients

“…False-positive results of PET examination include, on the other hand, some benign pulmonary conditions such as tuberculosis and sarcoidosis due to monocytes increased turnover [16], which lowers PET positive predictive value (PPV). Dual-time-point PET acquisition has been proposed to discriminate between benign and malignant processes [16], in the evaluation of suspected secondary liver lesions [17] and in distinguishing between benign and malignant lung nodules [18,19]. A lesion is likely to be malignant if the SUV increases over time, whereas it is likely to be benign if the SUV is stable or decreases ≤10% [19].…”

“…D'altro canto esiste la possibilità di falsi positivi in PET per reperti polmonari benigni, come tubercolosi e sarcoidosi, a causa dell'aumentato turn-over monocitario espresso [16], che possono inficiare il valore predittivo positivo della metodica. È stata dunque proposta la PET con metodica di acquisizione dual-time per migliorare la performance nella diagnosi differenziale fra processi benigni e maligni [16], ad esempio in caso di sospette lesioni secondarie epatiche [17] e dei noduli polmonari benigni e maligni [18,19]: una lesione ha maggiore probabilità di essere maligna se il valore di SUV aumenta nel tempo mentre è tendenzialmente benigna se tale valore rimane stabile o si riduce al di sotto del 10% [19]. Studi eseguiti sia in vitro che in vivo mostrano che le cellule maligne tendono ad accumulare il 18 F-FDG nel tempo con incremento di SUV fino al 10%, mentre le cellule del sistema monocito-macrofagico mostrano SUV stabile o decrescente (≤10%) [16].…”