Patients were required to fast for at least 6 h before PET/CT scan. 18F-FDG was given intravenously at a dose of 7.4 MBq/kg. After resting for 1 h, the PET/CT scan was performed using a Siemens Biograph 16HR PET/CT Scanner (Knoxville, TN, USA). The patient kept a supine position with elbows on the forehead in a full carbon flatbed. The scanning range was from the proximal thighs to the head. CT scanning was performed before PET acquisition. The parameters of CT scanning were as follows: 120 kV, 110 mA, slice thickness of 5 mm, rotation time of 0.5 s, and pitch of 1 mm. The PET scan duration was 2–3 min per bed for 6–8 beds. The PET images were reconstructed using the ordered subset maximum expectation iteration method after attenuation correction using CT images. More details have been described previously.22 (link)
SUV-T was defined as the maximum SUV (SUVmax) of the primary tumor, SUV-N was defined as SUVmax of the lymph nodes, and SUV NTR was defined as the lymph NTR of SUVmax. For multiple lymph nodes, SUVmax is defined as the highest SUVmax of the neck lymph nodes, regardless of the size of the lymph nodes.
SUV-T was defined as the maximum SUV (SUVmax) of the primary tumor, SUV-N was defined as SUVmax of the lymph nodes, and SUV NTR was defined as the lymph NTR of SUVmax. For multiple lymph nodes, SUVmax is defined as the highest SUVmax of the neck lymph nodes, regardless of the size of the lymph nodes.
