Incidental findings on brain magnetic resonance imaging: systematic review and meta-analysis.
OBJECTIVE
To quantify the prevalence of incidental findings on magnetic resonance imaging (MRI) of the brain.


METHODS
Systematic review and meta-analysis of observational studies.


METHODS
Ovid Medline (1950 to May 2008), Embase (1980 to May 2008), and bibliographies of relevant articles. Review methods Two reviewers sought and assessed studies of people without neurological symptoms who underwent MRI of the brain with or without intravenous contrast for research purposes or for occupational, clinical, or commercial screening.


METHODS
Overall disease specific and age specific prevalence of incidental brain findings, calculated by meta-analysis of pooled proportions using DerSimonian-Laird weights in a random effects model.


RESULTS
In 16 studies, 135 of 19 559 people had neoplastic incidental brain findings (prevalence 0.70%, 95% confidence interval 0.47% to 0.98%), and prevalence increased with age (chi(2) for linear trend, P=0.003). In 15 studies, 375 of 15 559 people had non-neoplastic incidental brain findings (prevalence 2.0%, 1.1% to 3.1%, excluding white matter hyperintensities, silent infarcts, and microbleeds). The number of asymptomatic people needed to scan to detect any incidental brain finding was 37. The prevalence of incidental brain findings was higher in studies using high resolution MRI sequences than in those using standard resolution sequences (4.3% v 1.7%, P<0.001). The prevalence of neoplastic incidental brain findings increased with age.


CONCLUSIONS
Incidental findings on brain MRI are common, prevalence increases with age, and detection is more likely using high resolution MRI sequences than standard resolution sequences. These findings deserve to be mentioned when obtaining informed consent for brain MRI in research and clinical practice but are not sufficient to justify screening healthy asymptomatic people.
Morris
Zoe
Z
Division of Clinical Neurosciences, Western General Hospital, Edinburgh.
Whiteley
William N
WN
Longstreth
W T
WT
Weber
Frank
F
Lee
Yi-Chung
YC
Tsushima
Yoshito
Y
Alphs
Hannah
H
Ladd
Susanne C
SC
Warlow
Charles
C
Wardlaw
Joanna M
JM
Al-Shahi Salman
Rustam
R
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001927:Brain Diseases / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D033162:Incidental Findings; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D055815:Young Adult
J Neurosurg. 2000 Jun;92(6):920-6
10839250
Neurosurgery. 2004 Oct;55(4):767-75; discussion 775-8
15458585
Lancet. 2003 Jul 12;362(9378):103-10
12867109
Mayo Clin Proc. 2008 May;83(5):563-5
18452687
Neurosurgery. 1995 Jul;37(1):11-5; discussion 15-6
8587669
Arch Intern Med. 2004 Dec 13-27;164(22):2415-9
15596630
BMJ. 2008 Sep 22;337:a1591
18809589
Neurology. 2008 Jan 29;70(5):384-90
18227420
Radiologe. 2002 Aug;42(8):622-9
12426741
Brain. 2007 Aug;130(Pt 8):1988-2003
17322562
J Med Screen. 2007;14(1):2-4
17362563
Control Clin Trials. 1986 Sep;7(3):177-88
3802833
Aviat Space Environ Med. 2004 Feb;75(2):158-61
14960052
Lancet Neurol. 2008 Mar;7(3):223-30
18243054
AJNR Am J Neuroradiol. 1994 Oct;15(9):1625-33
7847205
Stroke. 2000 Nov;31(11):2742-50
11062304
Stroke. 1999 Aug;30(8):1621-7
10436111
J Neurosurg. 2006 Oct;105(4):538-43
17044555
Nature. 2005 May 5;435(7038):17
15874992
Lancet Neurol. 2007 Jul;6(7):611-9
17582361
J Neurol Neurosurg Psychiatry. 2005 Nov;76(11):1558-64
16227551
Lancet Neurol. 2005 Nov;4(11):760-70
16239183
J Med Ethics. 2009 Mar;35(3):194-9
19251973
Pediatr Clin North Am. 2004 Apr;51(2):507-27
15062682
AJNR Am J Neuroradiol. 2004 Apr;25(4):520-2
15090335
J Law Med Ethics. 2008 Summer;36(2):219-48, 211
18547191