Quick Overview

The Partial Volume Artifact is caused by imaging voxel containing two different tissues and therefore possessing a signal average of both tissues.

Take thinner slices (smaller voxel), but this may result in poorer signal to noise ratio in the image.

See Partial Volume Effect.

The partial volume effect is the loss of contrast between two adjacent tissues in an image caused by insufficient resolution so that more than one tissue type occupies the same voxel (or pixel). That may induce a partial volume artifact, dependent on the size of the image voxel. If fat and water spins occupy the same voxel, their signals interfere destructively. A small amount of water signal may be eliminated by a larger lipid signal from the same voxel, resulting in a voxel that appears to contain only lipid. The partial volume effect is minimal with thin slice thickness and sufficiently high resolution, so that fat and water or other different structures are unlikely to occupy the same voxel.

Take thinner slices, and higher resolution (smaller voxel), but remain this may result in poorer signal to noise ratio in the image.

The quality factor (Q) applies to any resonant circuit component; most often the quality factor of the coil determines the overall Q of the circuit.
Inversely related to the fraction of the energy in an oscillating system lost in one oscillation cycle. Q is inversely related to the range of frequency over which the system will exhibit resonance.
In a parallel tuned circuit (such as used in a MR coil), the quality factor is defined as:
Q = vL/R
where L is the coil inductance, R is the circuit resistance, and v is the angular frequency. Increasing quality factor results in improving the signal to noise ratio SNR by a factor √Q and also produces a sharper frequency response (decreased band width). The Q of a coil will depend on the circumstances under which it is measured, e.g. whether it is 'unloaded' (no patient) or 'loaded' (patient).

A coil is a large inductor with a considerable dimension and a defined wavelength, commonly used in configurations for MR imaging. The frequency of the radio frequency coil is defined by the Larmor relationship.
The MRI image quality depends on the signal to noise ratio (SNR) of the acquired signal from the patient. Several MR imaging coils are necessary to handle the diversity of applications. Large coils have a large measurement field, but low signal intensity and vice versa (see also coil diameter). The closer the coil to the object, the stronger the signal - the smaller the volume, the higher the SNR. SNR is very important in obtaining clear images of the human body. The shape of the coil depends on the image sampling. The best available homogeneity can be reached by choice of the appropriate coil type and correct coil positioning. Orientation is critical to the sensitivity of the RF coil and therefore the coil should be perpendicular to the static magnetic field.

RF coils can be differentiated by there function into three general categories:
The RF signal is in the range of 10 to 100 MHz. During a typical set of clinical image measurements, the entire frequency spectrum of interest is of the order 10 kHz, which is an extremely narrow band, considering that the center frequency is about 100 MHz. This allows the use of single-frequency matching techniques for coils because their inherent bandwidth always exceeds the image bandwidth. The multi turn solenoid, bird cage coil, single turn solenoid, and saddle coil are typically operated as the transmitter and receiver of RF energy. The surface and phased array coils are typically operated as a receive only coil.

See also the related poll result: '3rd party coils are better than the original manufacturer coils'

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

RF noise, which often appears as static on the image, can be caused by a medical device located anywhere in the MR procedure room. RF noise is a result of excessive electromagnetic emissions from the device that interference with the proper operation of the MR scanner. The interference is attenuated and aliased in the frequency direction.

In the first case try to eliminate the factor of disturbance, if the problem persists screen the magnet- and room shielding.

See also Signal to Noise Ratio.