Imeron 400 mct

Prior to the ablation procedure, all patients underwent transthoracic and transesophageal echocardiography to exclude possible LA thrombus formation. Additionally, individual left atrial anatomy was revealed using a 64‐slice CT scanner (Brilliance 64, Philips Medical Systems, Cleveland, OH, USA) with retrospective electrocardiography (ECG) gating and 3D reconstruction prior to the procedure. Scanning was performed at 120 kVp, with an effective tube current of 600 mAs. The slice collimation was 64 × 0.625 mm, with a gantry rotation time of 0.4 s and a pitch of 0.2. Images were reconstructed at 0.9 mm slice thickness at increments of 0.45 mm. Contrast enhancement with 80 ml of contrast agent (Imeron 400 MCT, Iomeprol 81.65 g/100 ml, Bracco, Konstanz, Germany) was injected at a flow rate of 5 ml/s and followed by a 50‐ml saline flush. A blinded observer (JP) analyzed, segmented, and measured each CCTA image visually and quantitatively with regard to the defined parameters and the morphological classification of the LAA using EnSite Precision™ (Abbott Medical GmbH, Eschborn, Germany). Multiplan volume‐rendered post‐processing was used to acquire a 3D perspective. After anatomical segmentation into PV, LA, and LAA, all 2‐dimensional (2D) and 3D measurements were conducted.

CT was performed with a 128-slice CT scanner (Ingenuity 128, Philips, Hamburg, Germany). In n = 38 cases (42% of patients), intravenous iodine-based contrast medium (60 mL Imeron 400 MCT, Bracco Imaging Germany GmbH, Konstanz, Germany) was injected at a rate of 4.0 mL/s via a peripheral venous line. Automatic bolus tracking was performed in the aorta descenders with a trigger of 100 Hounsfield units (HU). Typical imaging parameters were: 100 kVp; 125 mAs; slice thickness,1 mm; pitch, 0.9.

The acquisitions were performed on a dual-source CT-scanner (SOMATOM Force, Siemens Healthcare). A test bolus slice was scanned with intravenous injection of 10 ml contrast medium (400 mg iodine/ml; Imeron 400 MCT, Bracco Imaging) followed by 30 ml of normal saline at 4 ml/s. Time to peak (TTP) opacification in the left ventricle was identified from the test bolus time-density curve and set as a fixed delay for the following main acquisition. This timepoint was chosen according to the work from Masy et al. [15 (link)] so that lung parenchyma is expected to have an optimal contrast enhancement. The DECT scan was obtained using 150Sn/90 kVp and 0.6 mm collimation with injection of 50 ml contrast medium followed by 50 ml of normal saline flush at 4 ml/s. The tube current was modulated as a function of angle and position along the Z-axis (CARE Dose 4D, Siemens Healthcare). Scan direction was caudocranial with coverage from diaphragm to lung apex in held gentle inspiration (to avoid Valsalva maneuver). Reconstructions used a 1 mm slice thickness with a QR40 convolution kernel.
Lung PBV quantification (derived iodine maps) was performed using syngo.CT DE Lung Analysis (syngo Multimodality Workplace, Siemens Healthcare). In order to minimize noise artefacts, a 3D Gaussian-smoothing filter (standard deviation of 2) was applied to CT-PBV maps using MATLAB (R2018b, MathWorks).

CT images were acquired with one DLCT scanner (IQon Spectral CT, Philips Healthcare). For all scans, a routine abdominal CT protocol was used with a tube voltage of 120 keV. Non-contrast-enhanced (NE) scans had an exposure of 107 ± 49 mAs (mean ± SD) and a mean CT dose index (CTDI_vol) of 9.7 ± 4.5 mGy; contrast-enhanced (CE) scans had an exposure of 110 ± 43 mAs and a mean CTDI_vol of 10.0 ± 3.9 mGy.
CE scans were performed using iomeprol, a non-ionic iodinated contrast agent for intravenous application (Imeron 400 MCT, Bracco Imaging Deutschland GmbH). Per routine clinical protocol and depending on the clinical situation, a volume of 50 to 70 ml was administered with a flow rate of 3 ml/s. Arterial phases were triggered when the average CT numbers of a volume of interest (VOI) in the descending thoracic aorta exceeded a threshold value of 150 HU. The portal-venous phases started 70 s after contrast administration.

All CT examinations were performed on an 80-slice CT scanner (Aquilion PRIME, Canon Medical Systems, Otawara, Japan). A biphasic contrast administration protocol was used. The first bolus of a 50 mL contrast agent (Imeron 400 MCT, Bracco) was followed by a 50 mL flush of saline. After 55 sec, the second bolus of 30 mL contrast agent was followed by a 40 mL saline flush to differentiate arterial vessels in the H&N area. After 18 s, a helical scan covering the entire neck from the frontal sinus to the aortic arch was acquired. Routinely, iterative reconstruction (AIDR3D, standard level) was applied. In those cases, where metal dental restorations were detected on the scout view, an additional dataset using Single-Energy Metal Artifact Reduction (SEMAR) was reconstructed. Scan parameters were: Auto-kV and Auto-mA with an SD of 7.5, 0.75 sec rotation time, 80 × 0.5 mm collimation, and pitch factor of 0.813.