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Contrast-enhanced magnetic resonance imaging has become a routine diagnostic imaging procedure. Reports in the literature document that 2 of the 4 available gadolinium-based magnetic resonance imaging contrast agents, gadodiamide (Omniscan) and gadoversetamide (OptiMARK), are less stable and readily undergo dechelation. In vitro, this dechelation can result in interference with the most common laboratory methods used to measure total plasma or serum calcium. The result of total calcium measurement soon after contrast-enhanced magnetic resonance imaging with these interfering contrast agents is a spurious lowering of the total calcium level. This low calcium measurement may result in a value consistent with hypocalcemia and can persist in patients with renal insufficiency and in patients receiving higher doses of contrast agent. Alternatively, a clinically significant elevated calcium level may be overlooked because of the artificially lowered value, two of the available gadolinium-based contrast agents, gadoteridol (ProHance) and gadopentetate dime-glumine (Magnevist), have not been to shown to interfere with total calcium measurement. A clinical practice algorithm for the laboratorian, the radiologist, and the clinician is presented to minimize the occurrence and consequences of a spuriously lowered total calcium level due to Omniscan- or OptiMARK-enhanced magnetic resonance imaging.
(Arch Pathol Lab Med. 2004;128:1151-1156)
During the past decade, use of contrast agents to enhance magnetic resonance (MR) images has provided substantial clinical advancement in diagnostic imaging, with improved lesion detection and characterization. In addition, pathophysiologic data can be obtained from contrast-enhanced MR imaging (MRI).1 Contrast-enhanced MRI is now a common medical procedure, used extensively in hospitals and outpatient facilities for the diagnosis of different neoplastic and inflammatory disorders. Recent survey data indicate that 20% to 25% of all MR studies use contrast enhancement.1 All of the approved intravenous contrast agents have equivalent abilities to enhance MR images and possess well-characterized safety profiles with a low incidence of adverse events.1 Recently, the observation has been made that 2 of the 4 MRI contrast agents approved for use in the United States interfere with the laboratory measurement of total calcium.2 In this review article, we discuss the mechanism of interference with this colorimetric assay and the potential clinical repercussions of this interference. In addition, an algorithm is provided for minimizing or preventing the possibility of this interference.
MRI CONTRAST AGENTS
It has been...