Purpose: To assess the clinical efficacy of magnetic resonance imaging (MRI) for neuroimaging and to provide guidelines for clinical practice.
Study selection: After a comprehensive literature search, studies of the diagnostic accuracy of MRI alone or compared with other tests and of any impact on therapeutic choices or patient outcomes were reviewed by independent readers, followed by discussion to reach consensus conclusions.
Data extraction: Of 3125 citations retrieved, 156 studies with original data could be rated according to methodologic criteria for study design. One article contributed grade A quality information about diagnostic accuracy, 28 were graded B or C, and 113 were graded D. One randomized trial and 2 comparison studies contributed grade B or C information about the impact on therapeutic choices. Only 2 studies surveyed health status before and after magnetic resonance scanning.
Results: For most abnormalities, the sensitivity of MRI is equal to or better than competing technologies. Magnetic resonance imaging shows greater contrast and detail than computed tomography (CT) but also shows more clinically silent abnormalities or incidental findings. A few studies found a modest impact on therapeutic choices but no impact on quality of life or disability. Costs for MRI are high. Computed tomography is sufficient for initial diagnosis of most mass lesions or intracranial hemorrhages requiring immediate intervention. Magnetic resonance imaging is more accurate in the temporal lobes, posterior fossa, brainstem, and spinal cord. For lumbar radiculopathy, MRI and plain spinal CT are as accurate as post-myelographic CT and are less invasive. The role of magnetic resonance angiography for carotid artery stenosis is being studied.
Conclusions: Although suggestions for appropriate use of MRI in clinical practice can be made, the supporting evidence in published studies is weak. Firm guidelines for appropriate use of MRI should be based on further clinical research using more rigorous methods.