Optima 450w gem

This study received approval by the Bergamo Ethics Committee (Reference number NCT04141852). The patient authorised the use of his clinical and imaging data for research purposes. A contrast-free MRI was acquired in a 72-year-old male 3 days after the creation of a native distal radio-cephalic side-to-end AVF. We acquired the CUBE sequence, previously optimised for AVF imaging [13 (link)] on a 1.5T scanner (GE, Optima 450w GEM) using a flexible 16-channel phased array medium coil, covering a region of approximately 3 and 5 cm above and below the anastomosis, respectively. Image segmentation was performed using the Vascular Modelling ToolKit [14 (link)]. Straight cylindrical flow extensions of five diameters were added to the vessels to ensure fully developed blood velocity at the inlets.

All subjects were scanned using a 1.5 T MR imaging system—Optima 450 w GEM (General Electric, GE Healthcare, Milwaukee, WI, USA). Imaging protocol included T1, T2, T2 Flair, SWI (susceptibility weighted image) and DWI (diffusion weighted image) sequences. MR angiography was performed using a TOF (time of flight) technique, which allows visualization of vessels without intravenous contrast injection. T1 3D post contrast sequences were performed in doubtful cases. The dose of gadolinium contrast was 0.1 mL/kg of body weight. DWI was the most important sequence in stroke patients as abnormalities in water diffusion in brain tissue change signals as early as 30 min after a stroke incident.
In the early hyperacute phase (first six hours after stroke) and with uncooperative patients, a fast protocol was applied with DWI, T2 Flair and T2 sequences.
Radiological limitations of movement artefacts—especially in the most valuable sequences—necessitated the use of quick sedation, even in some older children. All children up to six years old were sedated for examination.