Accupaque 350

CT imaging acquisitions were performed on a 256-row multidetector CT system (Revolution CT, GE Healthcare), with patients lying on their back, arms raised above their head, in a single breath-hold. Cardiac ECG-gated non-contrast images were first acquired to compute the aortic valve calcium score (these series were not analyzed as part of this study). In a second step, ECG-gated CT angiography of the carotid arteries, aorta, and iliac arteries was performed in the craniocaudal direction, following 100 mL of 350 mg/mL of iodinated contrast medium (Accupaque 350, GE Healthcare) injected into an antecubital vein (on the right side whenever possible). Images were analyzed by two radiologists, with any disagreement resolved by consensus or with the help of a third senior radiologist. Interrater variability for superior mesenteric artery (SMA) stenosis assessment has been evaluated previously (7 (link)). Data were prospectively collected in a dedicated file.

The outcome was the presence of an IPAL related to the PRI. Every patient had a total body or thoraco-abdominal CT scan including contrast enhanced arterial sequences as part of the emergency management. Arterial sequences were obtained after intra-venous injection of 120 ml of Accupaque™ 350 (Iohexol, GE Healthcare AG, Opfikon, Switzerland) diluted with sodium chloride. A region of interest (ROI) was placed on the aorta to exactly define the arterial phase, which was followed by venous series in all cases, and sometimes by late acquisitions if deemed necessary. Some patients additionally had angiography and embolization if needed. All the vascular images were reviewed by one of the authors (SB, board-certified radiologist), and every IPAL was noted and precisely described in terms of localization.

Patients were examined on a commercially available spectral detector DECT scanner (IQon Spectral CT, Philips Healthcare) in a head first, supine position. All scans were performed after intravenous administration of 100 ml iodine-based contrast agent with a flow rate of 3.0 ml/s (Accupaque 350, GE Healthcare). Contrast administration was followed by a saline flush of 30 ml. Bolus tracking in the descending thoracic aorta indicated portal venous phase with a delay of 50 s after surpassing a threshold of 150 HU. Tube voltage was 120 kV, the tube current was modulated by DoseRight 3D-DOM (Philips Healthcare). The collimation was 64 × 0.625 mm and the pitch 0.671.

The CT scanners used for imaging were a Canon Aquilion 64 (64 slice), an Aquilion Prime (80 slice), an Aquilion One (320 slice) (Canon Medical Systems, Ōtawara, Japan), and a GE Lightspeed VCT (GEL) scanner. Iodine-containing contrast agents such as Accupaque 350 (GE Healthcare, Chicago, Ill, USA) and Ultravist 370 (Bayer Vital GmbH, Leverkusen, Germany) were used in weight-adapted doses. The standard examination algorithm consisted of an initial arterial examination of the upper abdomen 40 s after the start of the machine contrast injection and a subsequent venous phase of the abdomen and pelvis 120 s after contrast injection.

Spinal cords (n = 4 for each group) were contrasted prior to scanning with incubation in Accupaque-350 (GE Healthcare, Munich, Germany) diluted 1:2 in PBS for 48 h. The spinal cords were then placed on 2 mm thick and 4 mm wide extruded polystyrene boards (XPS) and fixed using parafilm. The mounted spinal cords were placed upright and evenly spaced around the inner wall of a cylindrical sample holder with 19 mm diameter and held in place with pieces of XPS boards. Up to four spinal cord samples were scanned at the same time. Scans were performed at 70 kVp with 85 μA and a 0.5 mm Al Filter. A total of 3,400 projections/180° were integrated 4 times for 650 ms and averaged. The scans were reconstructed to an isotropic resolution of 6 μm. Approximately 21 mm of spinal length was scanned with the lesion epicenter positioned in the center of the scan.
The scans were converted to DICOM slices and evaluated using Fiji (ImageJ v1.53a; Schindelin et al., 2012 (link)). The spinal cords were rotated and aligned on the Z-Axis of the image using the rotate function of TransformJ (version 2016/01/09). The images were cropped to the XY extent of the spinal cord and in the Z direction to at least 5 mm above and below the lesion epicenter. Due to damage during tissue manipulation, a rat of the sham group was excluded.