Magnetic Resonance Imaging-Based Screening for Asymptomatic Brain Tumors: A Review

Abstract

Brain tumors comprise 2% of all cancers but are disproportionately responsible for cancer-related deaths. The 5-year survival rate of glioblastoma, the most common form of malignant brain tumor, is only 4.7%, and the overall 5-year survival rate for any brain tumor is 34.4%. In light of the generally poor clinical outcomes associated with these malignancies, there has been interest in the concept of brain tumor screening through magnetic resonance imaging. Here, we will provide a general overview of the screening principles and brain tumor epidemiology, then highlight the major studies examining brain tumor prevalence in asymptomatic populations in order to assess the potential benefits and drawbacks of screening for brain tumors. IMPLICATIONS FOR PRACTICE: Magnetic resonance imaging (MRI) screening in healthy asymptomatic adults can detect both early gliomas and other benign central nervous system abnormalities. Further research is needed to determine whether MRI will improve overall morbidity and mortality for the screened populations and make screening a worthwhile endeavor.

Keywords: Asymptomatic; Brain tumor; Glioblastoma; Magnetic resonance imaging; Screening.

Figure 1.

Consolidated Standards of Reporting Trials (CONSORT) flow diagram of population‐based studies emphasized in this review article.

Figure 2.

Findings from the Rotterdam scan study, a Netherlands‐based prospective cohort study initiated in 1995 to evaluate participants using magnetic resonance imaging (MRI) in order to assess for and identify risk factors of structural intracranial pathology [52]. Bos and colleagues reported on 5,800 individuals with MRI studies to provide prevalence estimates of identified intracranial abnormalities and draw important gender‐based comparisons. The bar graph shows the prevalence of the six most common incidental findings on brain MR images in men and women separately. Exact numbers of participants with incidental findings are shown at the top of each bar. Symbols: *, One man and three women had two meningiomas each; †, Four men and five women had two aneurysms each, one woman had three aneurysms, and one woman had four aneurysms; ‡, Possible pituitary adenoma (13 in men and 14 in women) or pituitary cyst (19 in men and 21 in women); ¶, Two women had two cavernous angiomas each, and one man had three cavernous angiomas; #, Lack of flow in the cavernous internal carotid artery (19 in men and 6 in women) or the vertebral artery (five in men, three in women); **, Statistically significant differences (p < .05) in prevalence between men and women were found for meningiomas, aneurysms, arachnoid cysts, and large vessel occlusions. Both the figure and its caption have been reproduced with permission from Bos D, Poels MM, Adams HH et al. Prevalence, clinical management, and natural course of incidental findings on brain MR images: The population‐based Rotterdam scan study. Radiology 2016;281:507–515 [52]. © RSNA, 2016.

Figure 3.

Findings from a meta‐analysis of 16 studies (both pediatric and adult) that evaluated participants with magnetic resonance imaging to look for intracranial pathology [57]. The studies included a total of 19,559 individuals and were based in the U.S., Europe, Asia, and Australia [57]. Through their work, Morris and colleagues determined the prevalence of neoplastic and non‐neoplastic incidental findings across multiple age groups. This figure has been reproduced from Morris Z, Whiteley WN, Longstreth WT Jr et al. Incidental findings on brain magnetic resonance imaging: Systematic review and meta‐analysis. BMJ 2009;339:b3016 [57]. This is an open‐access article distributed under the terms of the Creative Commons Attribution Non‐commercial License.

Figure 4.

Forest plot from a meta‐analysis of 16 studies assessing participants for intracranial abnormalities using MRI [57]. The Forest plot shows the prevalence of neoplastic, vascular, inflammatory and cystic intracranial pathologies. Morris and colleagues provide important estimates of the “number needed to scan” to detect different intracranial abnormalities, a metric that is an essential consideration in the context of brain tumor screening. The figure has been reproduced from Morris Z, Whiteley WN, Longstreth WT Jr et al. Incidental findings on brain magnetic resonance imaging: Systematic review and meta‐analysis. BMJ 2009;339:b3016 [57]. This is an open‐access article distributed under the terms of the Creative Commons Attribution Non‐commercial License. Abbreviation: CI, confidence interval.