Metal-related artifact

Residual cardiac motion should be completely absent when performing coronary CTA for stent evaluation. While residual motion negatively affects all coronary CT exams, metal-related artifacts are especially increased. BCG gating, gantry rotation speed, heart rate, etc., apply as for all cardiac CT exams. 

Metal alloys were first used in the Bronze Age (1,400 B.C.-O B.C.), where serendipity led to the discovery that doping copper with other compounds drastically altered the physical properties of the material. Artifacts from the Middle East dating back to 3,000 B.C. are found to consist of arsenic-doped copper, due to the wide availability of lautite and domeykite ores, which are rich in both arsenic and copper. However, due to arsenic-related casualties, these alloys were quickly replaced with tin-copper alloys (bronze) that were widely used due to a lower melting point, higher hardness, and lower brittleness relative to their arsenic forerunner. 

The degradation of a metal artifact, defined as loss of functionality over time in relation to the intended use, may be due to corrosion, although corrosiou and degradation are not synonymous. The degradation may be a consequence of several phenomena, which, even related to corrosion only, are in fact quite diversified. 

During the course of work with museum artifacts, some contact with dusts and fibres is inevitable. Although these substances may be a nuisance, for the most part they will be non-toxic. Dusts of metal compounds may be encountered, and of these lead is by far the most important, as mentioned earlier. Increasing use is being made of glass fibre in museum work, whilst the hazards relating to the styrene which is evolved have also been mentioned previously. The glass fibres themselves are an irritant to the skin, and to the respiratory tract if they are inhaled, but almost certainly they have no other harmful effects. 

In complex cases of four-electrode measurement in highly resistive media with metal "pseudo-reference" electrodes the contact impedance may become significant, resulting in confounding results and equivalent circuits consisting of inductive, capacitive, and resistive elements related to an instrumental artifact and not to a physical condition of a studied system [15]. One therefore has... 

---