Light speed vct

All CT images were obtained using Siemens SOMATOM Definition Flash, Siemens SOMATOM Definition AS, Siemens SOMATOM Sensation 16, GE Optima CT660, GE Revolution CT, GE Bright Speed Elite, GE light speed VCT, and TOSHIBA CT64-TSX-01A64. The CT protocols were as follows: 120 kVp; tube current, 150–200 mAs with automatic tube current modulation. The section thickness ranged between 0.7 mm and 1.5 mm, and the image size was 512 × 512 pixels. The detailed protocol and contrast materials are summarized in Table E1. Three patients received solely non-enhanced CT scan due to renal function impairment, while the other patients received both non-enhanced and enhanced CT scan. Contrast enhanced images were obtained after intravenous administration of contrast medium (injection dose 60-120 mL at a rate of 1.5-3 ml/s) followed by a 20 ml saline flush. Contrast enhanced images were obtained 90s after contrast agent administration. All images were reconstructed into 5-mm sections.

Patients underwent contrast-enhanced CT with a biphasic pancreas protocol consisting of arterial or pancreatic phase and portal venous phase acquisitions. As CT scans were not all from the same institution, the exact contrast bolus volume, timing, and injection rate varied over the time period. In addition, there was inconsistent timing related to variation in CT protocols during the arterial/pancreatic phase imaging. This resulted in variable enhancement of the tumour and background pancreas. As a result, in many cases, the tumour was inconsistently visualized on the arterial/pancreatic phase. The portal phase was consistent in timing and enhancement of background tissue across the entire cohorts. For these reasons, all pancreatic cancer boundaries were drawn on the portal venous phase of acquisition as this phase was most consistent across all exams. CT images were reconstructed with 5 mm and 2 mm intervals for the first cohort and second cohort, respectively. Detector width was 40 mm and kV was 120 kVp for the portal phase for both cohorts. Examination was performed on a 64 row multidetector helical CT (first cohort: GE Medical Systems, LightSpeed VCT, second cohort: Toshiba, Aquilion).