What Is the SFG? The SFG characterizes the temporally fixed spatial gradient magnetic field surrounding the MR system. The SFG is the rate of change in the magnetic field as a function of position around the MR system. The SFG decreases with increasing distance from the ends of a typical cylindrical, horizontal-field magnet.

Several consensus documents are now recommending 3T over 1.5 T, e.g. multiparametric MRI (mpMRI) of the prostate, 14 myocardial perfusion and late gadolinium enhanced cardiac imaging, 15 and the use of MRI in multiple sclerosis. 16 Alternatively, the improved SNR can be traded for shorter examination times, either by simply reducing the NSA ...

When one purchases an MR system, the vendor provides detailed field maps to help identify each of these fields in and around the scanner. These exact values are important because MR Conditional implants frequently have limits on the maximal SG or SGP through which they are allowed to pass.

Some manufacturer-provided SFG maps depict the spatial field gradient in an axial plane with equidistant, concentric circles around the scanner's isocenter (Fig. 1). Each circle represents the...

2023年3月28日 · Lower static magnetic fields do produce less torque, just as lesser spatial field gradients (SFG) produce lower attraction and Lenz-related forces. Several new MR systems’ variations in orientation of the static field and SFG are also accompanied by changes in the direction of the resultant translational and torque-related forces.

MR vendors specify location and magnitude of the SFG in T/m, while MR Conditional labels use G/cm (the latter being 100 times the T/m values). For example, typical “MR Conditional” labels may quote a limiting gradient of 720 Gauss/cm (G/cm); while recent compact cylindrical bore magnet designs often exceed 18 T/m (= 1800 G/cm).

Each MRI manufacturer provides a system manual with spatial gradient field maps specific to the MR system. Often the maps are shown in different angles, such as profile, sagittal, top, or front views and are crucial because MR Conditional implants have maximum spatial field gradient limits that they can experience.

2022 Dubai Advanced MRI Safety Seminar. Static Magnet Fields: Effects / Volumes / Forces Harms. Static Magnetic Field. Translation - Magnetizability • Magnetic Saturation • For Many Steel Materials, Saturation Achieved Very Quickly • Once Saturation Achieved, Spatial Field Gradient (SFG) Main Driver of Translation.

2019年7月29日 · With regular updates to these guidelines, the latest MR safety concerns can be accounted for to ensure a safer MR environment where dangers are minimized. Level of Evidence: 1 Technical Efficacy...

2006年12月1日 · Precise rules for locating the anatomical boundaries of the dorsolateral prefrontal cortex (DLPFC) or its subdivisions, i.e., superior, inferior and middle frontal gyri (SFG, IFG and MFG) on magnetic resonance images (MRI), have not been defined. The present study describes the inter-rater reliabili …