Imaging decisions (Berlin, Germany)最新文献

The overall iodine load is the key determinant for the imaging of solid organs. For CTA studies, however, injection duration and particularly the iodine delivery rate (IDR; given in g iodine/s) are the determining factors for the quality of the bolus. An optimized contrast injection is mandatory to achieve high quality CT scans with homogeneous attenuation and high contrast throughout the entire data-set.

Gadofosveset Trisodium (Vasovist) is a safe and well tolerated intravascular contrast agent, currently approved in Europe and Canada. It has proved to be effective in the asessment of vascular diseases at all vascular territories. The possibility to image at steady state opens new horizons by increasing the spatial resolution and the robustness of diagnostic MRA. Initial studies proved the possibility to image beyond the vascular territory and to assess enhancing lesions as known from studies with standard contrast agents.

After administration of contrast media the incidence of acute renal failure requiring dialysis is low. Clinical studies on contrast-induced nephropathy (CIN) therefore use a relative or absolute increase in serum creatinine as a surrogate marker. However, there is no generally accepted threshold for increases in creatinine. The lack of consistency in the definition of CIN makes it difficult to compare trials. The serum creatinine level is also only a poor marker of renal function. Increases in serum creatinine after contrast examination are associated with increased mortality, morbidity and longer hospital stays. However, such correlations have been shown only for coronary interventions. Not all cases of renal failure following cardiac angiography are necessarily related to the contrast medium, as in these patients there are several other reasons for loss of renal function. There are no studies showing a correlation between patient outcome and CIN after intravenous administration of contrast media. While the pathophysiology of CIN is not yet completely understood, it most certainly involves the interplay of multiple factors. It is highly likely that direct tubular toxicity of the CM contributes to the aetiology, whereas the role of the physicochemical properties of CM may have been over-interpreted. There is an ongoing controversy as to whether the iso-osmolar CM iodixanol is better tolerated by the kidneys than low-osmolar CM (LOCM). Some randomized trials have demonstrated benefits of this substance. However, to date meta-analyses and registry studies have not shown a consistent picture. In the last few months some randomized trials have been published which have not found an advantage of iodixanol over LOMC, whether administered intra-arterially or intravenously.

This work describes the clinical advantages of highly concentrated MRI contrast media as well as double or even treble dose contrast application.

MR Imaging has revealed high performance for focal liver lesion detection and characterization during a single examination procedure. Liver-specific contrast media have shown to further increase the detection rate. The first liver-specific contrast media approved where not injected as a bolus avoiding the acquisition of early dynamic sequences. The recently approved gadolinium-based agent gadoxetic acid is offering for the first time a combination of an excellent and extracellular space contrast medium-equivalent safety profile, a high diagnostic accuracy in lesion detection and characterisation by a highly liver-specific uptake.

For more than 10 years it has been believed that gadolinium-based contrast agents in doses used for magnetic resonance imaging (MRI) are relatively safe with regard to acute non-renal and renal adverse reactions and delayed reactions. However, recent observations have shown that it may not be the case in patients with reduced renal function as gadolinium-based contrast agents may trigger the development of fibrosis in all parts of the body so-called nephrogenic systemic fibrosis (NSF). Its primary predilection is the skin. Unrelated to the development of NSF, contrast-induced nephropathy may occur after administration of gadolinium-based contrast agents. The current review updates the recent developments regarding the severe delayed reaction. However, the fear of NSF should not lead to a denial of a well-indicated enhanced MRI examination.