Iqon spectral

CT examinations were performed without administration of intravenous or oral contrast medium on one of our six multidetector CT scanners (SOMATOM Force, SOMATOM Definition Flash, SOMATOM Definition Edge; Siemens, Forchheim, Germany; GE Discovery, GE Revolution; VCT, Boston, MA, USA; IQon Spectral, Philips, Best, the Netherlands). Patients were scanned in supine position, with head first and the arms straight beside the body and hands placed over the upper thighs. The field of view was adapted to the patient’s circumference.
WBLDCT imaging parameters per used device are depicted in Table 1.Table 1

Whole-body CT imaging parameters per device

Device	No. of slices per rotation	Tube voltage (kVp)	Tube current modulation parameters	Collimation width	Rotation time (s)	Pitch
Revolution CT, GE	256	120	20 (noise index)	80 mm	0.5	0.992
Discovery CT750, GE	64	120	20 (noise index)	40 mm	0.5	0.984
Definition Edge, Siemens	128	120	70 (quality reference mAs)	38.4 mm	0.5	1
Definition Flash, Siemens	128	120	70 (quality reference mAs)	38.4 mm	0.5	1
SOMATOM Force, Siemens	192	120	70 (quality reference mAs)	57.6 mm	0.5	1
IQon, Philips	128	120	12 (dose right index)	40 mm	0.5	1.171

The CT scans were performed on a Brilliance iCT 256, an IQon-spectral and a Brilliance 64 scanner (Philips Healthcare, Best, The Netherlands). CT examination was performed with a tube voltage of 120 kV and a reference tube current of 127 mAs, 116 mAs, and 102 mAs for the three scanners respectively. A gantry rotation time of 0.4 s, 0.27 s and 0.4 s respectively and a detector collimation of: 128 × 0.625 mm, 64 × 0.625 mm, and 64 × 0.625 mm respectively. For the unenhanced phases, images were displayed in the axial plane as 5 mm-thick sections with 4 mm increments. The portal venous phase images were displayed in axial, coronal, and sagittal plane, with 5 mm-thick slices and 4 mm increments. A B (abdominal) kernel at iDose level 3 was used to reconstruct the images. The scan range was the upper abdomen for the unenhanced phase. For the portal venous phase the range was set 1 cm superior of the diaphragm to the lower pelvis.
Bolus tracking was used to determine imaging timing, by measuring a circular region of interest (ROI) in the abdominal aorta. Delay post-threshold (150 HU) before scanning was set at 90 s for the portal venous phase.

All patients underwent unenhanced and dual-phase contrast-enhanced CT using three CT scanners (Definition flash, Siemens, Forchheim, Germany/ in Guangzhou; IQon Spectral, Philips Healthcare, Amsterdam, Netherlands/ in Guangzhou; Aquilion One 750W, Canon, Tokyo, Japan/ in Zhuhai). Imaging parameters were: tube voltage 120 kV, tube current 250 mA, section interval 5 mm, section thickness 5 mm, and matrix 512 mm × 512 mm. After conventional unenhanced imaging, 100–120 ml iopromide (Ultravist 370, Bayer Schering Pharma, Germany) was injected into the median cubital vein via a pump injector (MEDRADStellant CT, Ulrich Medical, Ulm, Germany) at 3–4 ml/s. The AP scan was triggered by aortic enhancement. The VP scan started at a delay of 60 s from the beginning of contrast injection.
One radiologist (LH) with 18 years of experience analyzed the CT images to ensure the renal masses had < 25% enhancing tissue (i.e. lesions were cystic masses), confirm the Bosniak class (Version 2019), and determine the size of the CRMs.