The discussion gives a critical appraisal of the main findings. Disease categories were ordered by the level of evidence for the ability of non-contrast-enhanced MRI to replace contrast-enhanced MRI in a clinical setting. Then, we compare the diagnostic value and clinical applicability of non-contrast-enhanced with contrast-enhanced sequences in ten common diseases affecting the brain and report relevant statistical measures regarding diagnostic performance. Briefly, the topic of dynamic contrast-enhanced MRI is discussed. We describe the mechanism and limitations of GBCA contrast enhancement as well as the techniques that may serve as alternatives to GBCA contrast enhancement. The aim of this paper is to review the potential use of non-contrast-enhanced MRI instead of contrast-enhanced MRI for specific diagnostic questions in neuroradiology. Only a limited number of studies have been designed to compare the diagnostic efficacy for non-contrast-enhanced MRI compared to contrast-enhanced techniques. In the light of technological advances, additional costs, and possible long-term risks of GBCAs, the current role of GBCAs in neuroimaging can be discussed and re-evaluated. Furthermore, contrast enhancement adds to the cost of the MRI examination due to the cost of the additional scan time and of the contrast agent itself. Current recommendations of the use of GBCA in clinical practice and research now emphasize that GBCAs per standard practice should only be used when absolutely necessary and that GBCA can be used in research settings with appropriate guidance of protocols and ethical review board approval with informed patient consent. Neither of these reports demonstrated any association with clinical symptoms. Recently, gadolinium deposition was been reported in the deep gray matter of the brain and in the bone. More restrictive use of GBCAs in patients with renal impairment and the introduction of more stable non-linear GBCA chelates have lowered the incidence of nephrogenic systemic fibrosis. However, after several reports on the association between nephrogenic systemic fibrosis and GBCA exposure in patients with renal impairment, some linear GBCAs were withdrawn from the market or their indication was restricted. The use of GBCAs was initially considered safe without reported acute adverse events or long-term risks. In addition, GBCA was occasionally used for patients unsuitable for iodine-based contrast agent in CT examinations.

The effect of GBCAs in MRI is rendering a higher signal on T1-weighted images due to shortening of T1 relaxation time. Gadolinium-based contrast agents (GBCAs) in MRI were introduced in clinical practice in the 1980s to increase lesion detection and improve the disease characterization for many cerebral and vascular pathologies investigated with MRI. However, some diagnoses still require contrast-enhanced imaging for a complete examination. In general, non-contrast-enhanced techniques showed comparable diagnostic performance to contrast-enhanced MRI for specific diagnostic questions. These specific diseases include primary brain tumors, metastases, abscess, multiple sclerosis, and vascular conditions such as aneurysm, arteriovenous malformation, arteriovenous fistula, intracranial carotid artery occlusive disease, hemorrhagic, and ischemic stroke. Ten common diseases were identified for which studies reported comparisons of non-contrast-enhanced and contrast-enhanced MRI. Non-contrast-enhanced MRIs discussed in this review are arterial spin labeling (ASL), time of flight (TOF), phase contrast (PC), diffusion-weighted imaging (DWI), magnetic resonance spectroscopy (MRS), susceptibility weighted imaging (SWI), and amide proton transferВ (APT) imaging. Advantages and disadvantages together with the diagnostic performance of each method are detailed. Clinical studies on the diagnostic performance of non-contrast-enhanced as well as contrast-enhanced MRI methods, both well established and newly proposed, were included.

This review focuses on non-contrast-enhanced MRI techniques that can serve as alternatives for the use of GBCAs. Some linear GBCAs were restricted from use by the European Medicines Agency (EMA) in 2017. Hence, new guidelines from the International Society for Magnetic Resonance in Medicine advocate cautious use of GBCA in clinical and research practice.

Gadolinium deposition has also been found in deep brain structures, although it is of unclear clinical relevance. However, some non-ionic linear GBCAs have been associated with the development of nephrogenic systemic fibrosis in patients with kidney failure.

These agents, introduced in the late 1980s, are in wide use today. Gadolinium-based contrast agents (GBCAs) increase lesion detection and improve disease characterization for many cerebral pathologies investigated with MRI.

Inmr add structure to nmr