Somatom definition flash scanner

CT scans of the distal tibia at high‐resolution mode were collected on a 128 slice Siemens SOMATOM Definition Flash scanner (Siemens, Forchheim, Germany) at the University of Iowa Comprehensive Lung Imaging Center. The scans were acquired in single tube spiral acquisition mode using the following parameters: 120 kV; 200 mA effective; 1 second rotation speed; pitch factor 1.0; detector rows 16; scan time 23.2 seconds; collimation 16 × 0.6 mm; total effective dose equivalent 170 μSv ≈ 20 days of environmental radiation in the United States. Siemens z‐UHR scan mode was applied enabling Siemens dual z sampling technology, which splits the signal on 0.6‐mm detectors delivering 0.3 mm effective spatial resolution in the z‐direction.⁽²⁹⁾ Images were reconstructed at 300 μm thickness and 200 μm slice‐spacing using a normal cone beam method with a special U70u kernel achieving high spatial resolution. Three repeat CT scans were collected for each specimen on the same day after repositioning the specimen on the scanner table between scans. A Gammex RMI 467 Tissue Characterization Phantom (Gammex RMI, Middleton, WI, USA) was scanned on each day of a tibia scan using the same protocol to calibrate CT numbers into BMD.

CT imaging was performed using a Somatom Definition Flash scanner (Siemens Medical Solutions, Erlangen, Germany). CACS was measured using the following parameters: 120 kV, 150 mA, and 3-mm thickness. CACS was calculated using an automated computerized system (Virtual Place, Raijin; AZE Inc., Tokyo, Japan) and the Agatston method, which involved multiplying the area of each calcified plaque by a density factor determined by the peak pixel intensity within the plaque. The plaque-specific scores for all the slices were added together. The density factor was 1, 2, 3, or 4 for plaques with peak intensities of 130–199, 200–299, 300–399, and ≥ 400 Hounsfield units (HU), respectively [15 (link)]. In addition, patients were divided into three groups according to CACS: CACS 0, CACS (1–99), and CACS (≥ 100).

To avoid movement artifacts, preoperative imaging was performed with patients under general anesthesia at a 3 T Magnetom Skyra scanner (Siemens Healthcare, Erlangen, Germany). Imaging parameters were used as previously described by Strotzer et al. [34 (link)]. MR imaging included a T1-weighted sequence + one and a half times dose of Gadolinium to visualize crucial blood vessels, a T2-weighted sequence parallel to the AC-PC line to visualize relevant subthalamic structures for targeting and a DTI sequence with 64 gradient directions. DTI imaging included b0 images as well as a b0 image with inverted phase-encoding direction (posterior to anterior, “P2A”). Targets were defined in the dorsolateral aspect of the STN based on the Beijani line [35 (link)] at the anterior border of the red nucleus at its biggest expansion. At the day of surgery, a CT scan with a CRW head ring (Integra Radionics, Burlington, VT) mounted on the patient’s head was performed for definition of stereotactic trajectories at a Somatom Definition Flash scanner (Siemens Healthcare, Erlangen, Germany). MR and CT imaging was fused with Brainlab^® iPlanNet 3.0 (BRAINLAB, Munich, Germany). Trajectories were defined avoiding blood vessels, sulci, and eloquent neuronal structures.

CT examination was performed with Siemens Somatom Definition FLASH scanner (Siemens, Germany), with contrast agent Iohexol Injection (300 mg/mL, dose 1.5mL/kg).
MRI examination was conducted with Siemens 3.0T trio class scanner (Siemens AG, Germany), and contrast agent was Gadolinium diethylenetriaminepenta-acetic acid (Gd-DTPA, Bayer Schering Pharm AG, Germany, dose 0.2 mmol/kg).
Each contrast-enhanced examination was recorded at 25s, 75s and 120s after contrast injection, corresponding to the arterial phase, portal phase and delayed phase.

Sedated animals were immobilized using a vacuum mattress and thermoplastic mask for reproducible positioning (Fig. S3). The CT reference point (calibrated room laser) was marked on the mask with radio-opaque markers and tattooed on the skin. Cardiac-gated (4-dimensional [D]), native and contrast-enhanced CT scans (10 phases) were acquired using a 64 row Siemens Somatom Definition Flash scanner (Siemens Healthcare, Forchheim, Germany). Scans were acquired at end-expiration using a 25 sec. respirator breath-hold remotely controlled through a Labview software interface (National Instruments, Austin, TX, USA). For enhanced scans, 50cc contrast medium were injected (4cc/sec, 8–10 sec. delay, Omnipaque 350 mg I/cc, GE Healthcare, USA). A field of view of 400 mm and 1 mm slice thickness was reconstructed. The native 4D-CT protocol was validated against the standard planning CT protocol of the Heidelberg Ion Beam Therapy Center (HIT) for correct HU and resulting ion beam ranges.