Ultravist

All the patients, who had fasted at least eight hours prior to the MDCT gastrography, received 10 mg of butyl scopolamine (Buscopan, Boehringer Ingelheim, Seoul, Korea) intravenously to decrease bowel peristalsis and to facilitate hypotonia, and they received 6 g of effervescent granules (Top, Taejoon Pharmaceuticals, Kyungkido, Korea) with 10 mL of water to achieve gastric distension just before CT. CTG was performed using a 16-MDCT scanner (Somatom Sensation 16, Siemens, Erlangan, Germany). The CT parameters included 16×0.75 mm detector configuration, 120 kVp, 120 mAs, 15 mm/sec table feed and 1-mm reconstruction with a 30% overgap. After ensuring adequate gastric distension on the scanogram, the arterial and delayed phase scans were obtained from the diaphragmatic dome to the lower edge of the stomach. The portal phase scans were obtained from the diaphragmatic dome to the symphysis pubis.
Triphasic CT scans were performed during the arterial phase (start of delay: 30 seconds) with the patient in the LPO position, during the portal phase (72 seconds) with the patient in the supine position and during the delayed phase (150 seconds) with the patient in the prone position after injection of 120 mL of nonionic contrast material (Ultravist; Schering, Berlin, Germany) at 4 mL/sec via the antecubital vein by using a 18-gauge needle and an automatic injector. The LPO position was performed by placing a pillow at the patient's back.

Four hundred seventy-two patients who underwent macroscopically complete surgical resection (EPP, P/D, and eP/D) (21 (link)) and had diagnostic quality preoperative imaging scans within 30 days prior to surgery were included in the study. For patients who had completed neoadjuvant chemotherapy, the scan following the last cycle was used. Of these, 303 patients (64.1%) underwent CT scans on the Sensation 64-MDCT scanner (Siemens Medical Solutions, Erlangen, Germany) with 120 kVp, 0.6 mm collimation, high-speed mode, a pitch equivalent of a 1.5-slice interval of 5 mm, and reconstructed in a slice thickness of 5 mm. Intravenous contrast consisting of 55 mL of contrast material (Ultravist 370 [iopromide], Bayer HealthCare, Berlin, Germany [formerly Schering]) was administered intravenously to 197 (41.7%) patients at 4 mL/s using an automated power injector.
For the remaining 169 (35.8%) patients, diagnostic quality CT scans were obtained for anatomic correction as part of an integrated PET-CT study (Discovery ST system, GE Healthcare, Chicago, USA) using 140 kVp and 75 mA, and reconstructed with 3.75 mm slice thickness at 3.25 mm intervals. No intravenous contrast was administered. The metabolic information from PET-CT studies was not considered in the current analysis.
Analysis of CT images was accomplished by an experienced thoracic radiologist (RRG). Qualitative and quantitative assessment of each scan was performed using barcoded data collection forms and following a standardized protocol. The CT images were analyzed qualitatively using the AJCC Cancer Staging Manual (7th ed.) (20 ). Each individual AJCC classification criterion defining T2–T4, N1–N3, and M1 was assessed for each patient, scored on a case report form as either involved or not involved by tumor, and compared with corresponding pathological assessment. Clinical stage was determined based on published stage groupings (20 ) and compared with pathological stage.
Quantitative analysis was performed on a PACS workstation. Volumetric assessment of the tumor was performed using Vitrea Enterprise suite 6.0 (Vital, MN) by semiautomatic segmentation of tumor area on serial axial images using Hounsfield thresholding (default 20–80) with manual correction to exclude pleural fluid and normal adjacent tissue, and integration across images (Figure 1, A–E) (12 (link),14 (link)). The integrated measurement caliper was used to quantify interlobular fissural thickening at its maximum thickness evident on axial CT images (Fmax) (Figure 1, F–I).

The DECT images were created via a 64-slice dual-source multi-detector CT scanner (Somatom Definition Flash; Siemens Healthcare, Forchheim, Germany). One mL/kg body weight iopromide (Ultravist 370 mg/mL; Bayer Schering Pharma, Berlin, Germany) was administered into the right antecubital vein with a flow rate of 5 mL/s, followed by 60 mL saline. A bolus tracking technique was used to pinpoint the area of interest (ROI) in the left ventricle (CARE-bolus; Siemens Healthcare). The data collection procedure was initiated at a predetermined time interval specified by a single ROI system with a trigger threshold of 200 Hounsfield units (HU) in the left ventricular blood pool. Data collection commenced eight seconds after triggering, with arterial phase data being gathered. Retrospective ECG pulsing with a low-pitch ECG-gated scan was used as the scan mode (a prospective protocol could not be applied due to the artifacts during the dual-energy protocol). All patients in the retrospective procedure received ECG dosage modulation. The CT dose index volume and the dosage-length product of all the scans were recorded.
Patients were encouraged to adopt the deep-inspiration breath-hold technique during the procedure, and the scan was conducted craniocaudally from the subcarinal level to the diaphragm. The limits of the reconstruction window of the initial axial pictures were set at 75% (end of diastolic phase) and 45% for the cardiac cycle (end of systolic phase).
For the myocardial evaluation, the high- (140 kV) and low-voltage (80 kV) information was reconstructed via a dual-energy convolution core (D30f) with a temporal resolution of 140 milliseconds and a thickness of 1.5 mm, with 1 mm increments utilized to maximize the signal-to-noise ratio. Next, the final data were analyzed using a three-material decomposition software platform (Syngo Multimodality Workplace; Siemens, Erlangen, Germany).