Indication-related dosing for magnetic resonance contrast media

Abstract

This presentation reviews the issue of contrast media dosing and imaging protocols for the optimal MR imaging detection and characterization of pathology. The cumulative clinical experience gained in performing contrast-enhanced MR examinations with gadolinium chelates indicates that a dose of 0.1 mmol/kg body weight provides safe and effective enhancement of most CNS pathology. Doses lower than 0.1 mmol/kg have been shown to be inadequate for delineating all but selected types of CNS pathology, such as masses with a high lesion to background ratio on post-contrast images (acoustic neuromas) or lesions located in areas in which the normal tissue very rapidly takes up contrast agent (e. g. microadenomas in the pituitary gland). Recent clinical studies have suggested a role for high dose gadolinium administration (up to 0.3 mmol/kg) for the optimal detection and delineation of cerebral metastases or other small or poorly enhancing lesions. Differences in the histopathologic characteristics (capillary permeability, vascularity, location, size) of specific diseased tissues may require varying doses or even a different contrast agent to be used for optimal imaging results. As new MR contrast agents and new scanning techniques are introduced, the specific diagnostic question posed will likely determine the choice of pulse sequence, contrast agent and dose used.

Currently used non-specific extracellular MR contrast media

“…Yuh et al [23] observed no significant side effects of gadoteridol for doses up to three times the standard dose. Lower doses also appear to be useful for MR urography [24] and CNS imaging [19].…”

“…Controversial issues concerning contrast-agent administration include: Which dose should be administered, and what is the optimal time interval between contrast-medium injection and MR imaging? A low dose (0.05 mmol/kg) is sufficient for the evaluation of pituitary adenomas and 2695 acoustic neurinomas because of their high intrinsic contrast [43], whereas it has been shown that double or triple doses (0.2-0.3 mmol/kg) are preferable for the detection of cerebral ischaemia in functional and dynamic studies, to characterize brain tumours and to differentiate tumour recurrence from tissue necrosis [19,20,23]. In addition, a multicentre study [50] showed that Gd-enhanced MR images provided additional information on 96% of intradural, extra-and intramedullary tumours, and 53% of extradural tumours.…”

“…The standard dose is 0.1 mmol/kg; however, higher or lower doses may be diagnostically more adequate [19] and Gd chelates are approved for different dose regimens (Table 1). Potential advantages of using Gd chelates at higher doses include better lesion enhancement, delineation and detectability of central nervous system (CNS) neoplasms [20].…”

Contrast Enhancement of Central Nervous System Lesions: Multicenter Intraindividual Crossover Comparative Study of Two MR Contrast Agents

“…This has been shown not only to benefit the detection and delineation of small or poorly enhancing metastatic lesions but also to improve delineation of the extent of involvement of primary CNS tumors, and thereby to facilitate the more accurate guidance of surgical resections and the better demarcation of target volumes for radiosurgery (20)(21)(22)(23)(24)(25)(26)(27)(28). The increased exposure of patients to contrast material and the increased costs related to higher dose or delayed scanning techniques, however, have limited the use of these techniques in MR imaging of the CNS (29,30).…”

Use of half-dose gadolinium-enhanced MRI and magnetization transfer saturation in brain tumors

“…Contrast agents shorten T1 relaxation time of tissues in which they accumulate and improve signal intensity on T1-weighted MR images. In current practice it is assumed that a dose of 0.1 mmol/kg gadolinium for MR imaging provides safe and effective enhancement of most intracranial tumors [1,2]. Several studies have analyzed the utility of using a higher dose of contrast agent for the MR evaluation of primary and secondary brain lesions.…”