This artifact looks like a pixel at the exact center, which is brighter or darker than the surroundings by the Fourier transformation of a constant raw data offset.

See Central Point Artifact.

Quick Overview

Radio frequency quadrature artifacts occur when the detector channels of the quadrature detector are disturbed.
A DC offset of one amplifier output can e.g., produce a bright point in the center of the field of view (see also central point artifact), or a higher gain of one detector channel can generate diagonally ghosting.

Radio frequency quadrature artifacts are technical faults and must be eliminated by the service.

Quick Overview
Please note that there are different common names for this artifact.

This artifact appears as a bright spot (or zipper line) in the image center. Central point artifacts are caused by a DC offset in the hardware. MRI scanners normally offer a software compensation (DC correction, baseline correction) for prevention.

Take care for a constant temperature. If the problem increases or keeps on existing, it should be addressed to the service.