Does intravenous contrast improve the diagnostic yield of fluorodeoxyglucose positron-emission tomography/computed tomography in patients with head-and-neck malignancy

In the present time, iodinated contrast agents are increasingly being used in the computed tomography (CT) component of positron-emission tomography (PET) study with the assumption that contrast-enhanced CT (CECT) will provide better diagnostic yield, although the utility of this procedure is still being debated. The aim of the study was to evaluate the effect of contrast CT on the diagnostic yield of PET-CT scan in patients with head-and-neck malignancies. In a prospective study, 204 patients (140 males and 64 females) of head-and-neck malignancies underwent contrast-enhanced and non enhanced fluorodeoxyglucose (FDG)-PET-CT for various clinical indications following informed consent. After a plain CT scan, CECT was done using iodinated contrast iopromide-370 at a dose of 1 ml/kg intravenously. After CECT acquisition, FDG-PET acquisition was done and images were reconstructed to obtain whole-body PET/CT and PET-CECT images. Both the modalities could detect similar number of primary lesions (n = 127), lymph nodal lesions (n = 118), and metastatic involvement (n = 55) with no significant difference between SUV_max. However, conspicuity of primary tumors and lymph nodal architecture was significantly better delineated with CECT, leading to better interpreter confidence. CECT data as part of the combined PET-CT examination provide precise anatomic localization and delineation of the primary tumor in comparison to non enhanced PET-CT. However, no significant diagnostic changes are noted in the nodal and metastatic staging. (author)