Correspondence
Incidental Findings on Brain MRI
N Engl J Med 2008; 358:853-855February 21, 2008
- Article
To the Editor:
Vernooij et al. (Nov. 1 issue)1 have contributed valuable knowledge about the prevalence of asymptomatic intracranial lesions. However, we disagree with their statement that many incidental lesions do not merit further evaluation or treatment.
The authors cite results of the International Study of Unruptured Intracranial Aneurysms (ISUIA) to justify not further evaluating small aneurysms,2 but conventional magnetic resonance sequences used in this study are unreliable in characterizing aneurysms. Digital subtraction angiography or computed tomographic or magnetic resonance angiography is a superior diagnostic technique.3 Furthermore, a significant proportion of subarachnoid hemorrhages result from small aneurysms, mandating careful risk assessment based on individual factors.4
Meningiomas and pituitary macroadenomas were diagnosed only on the basis of non-contrast magnetic resonance imaging (MRI). Although these lesions grow slowly, selected patients will benefit from early treatment: resection of smaller meningiomas is associated with less morbidity,5 and 9.5% of asymptomatic pituitary macroadenomas develop apoplexy,6 which may be prevented by early surgery. Malignant neoplasms may also mimic these lesions on MRI.
We agree that the natural history of these conditions is incompletely understood; therefore, we strongly urge that patients with such conditions be evaluated by an appropriate specialist for careful consideration of the individual history and risk factors and for the development of an optimal management plan.
6 ReferencesBrandon G. Rocque, M.D.
Mustafa K. Baskaya, M.D.
John S. Kuo, M.D., Ph.D.
University of Wisconsin, Madison, WI 537921
Vernooij MW ,Arfan Ikram M ,Tanghe HL , et al. Incidental findings on brain MRI in the general population. N Engl J Med 2007;357:1821-1828
Full Text | Web of Science | Medline2
Wiebers DO ,Whisnant JP ,Huston J III , et al. Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment. Lancet 2003;362:103-110
CrossRef | Web of Science | Medline3
Kouskouras C ,Charitanti A ,Giavroglou C , et al. Intracranial aneurysms: evaluation using CTA and MRA: correlation with DSA and intraoperative findings. Neuroradiology 2004;46:842-850
CrossRef | Web of Science | Medline4
Nahed BV ,DiLuna ML ,Morgan T , et al. Hypertension, age, and location predict rupture of small intracranial aneurysms. Neurosurgery 2005;57:676-683
CrossRef | Web of Science | Medline5
Alvernia JE ,Sindou MP . Preoperative neuroimaging findings as a predictor of the surgical plane of cleavage: prospective study of 100 consecutive cases of intracranial meningioma. J Neurosurg 2004;100:422-430
CrossRef | Web of Science | Medline6
Arita K ,Tominaga A ,Sugiyama K , et al. Natural course of incidentally found nonfunctioning pituitary adenoma, with special reference to pituitary apoplexy during follow-up examination. J Neurosurg 2006;104:884-891
CrossRef | Web of Science | Medline
To the Editor:
Vernooij et al. point out that incidental brain findings on MRI are common in the general population. We would like to report similar data from a Chinese population in Taiwan.
Between September 2, 2005, and January 2, 2007, a total of 2164 apparently healthy subjects underwent preventive whole-body MRI screening in Taichung Veterans General Hospital MRI Health Center, which is a self-referred body-imaging center, providing imaging services with the use of the Magnetom Avanto 1.5-T MRI scanner (Siemens). The mean (±SD) age of the study population was 51.8±10.6 years (range, 17 to 89), and 1234 of the subjects (57%) were men. Brain MRI was performed according to a standard protocol. Incidental brain findings were also common in our population, present in 180 persons (8.3%) (Table 1Table 1
Incidental Findings on 2164 Brain MRI Scans.). The age distribution, socioeconomic status, and ethnic background may call for a different spectrum of incidental brain MRI findings in a different population.Wei-Ju Lee, M.D.
Lei-Bin Chang, M.D.
Taichung Veterans General Hospital, Taichung 40705, TaiwanYi-Chung Lee, M.D.
National Yang-Ming University, Taipei 112, Taiwan
yclee@vghtc.gov. tw To the Editor:
In a population-based study, Vernooij and colleagues found that 7% of 2000 subjects had asymptomatic brain infarcts on MRI. Foerch and colleagues previously reported that most strokes (54%) in a large stroke registry were in the left side of the brain.1 They reviewed two studies showing that unrecognized strokes are more common in the right side of the brain. Can the authors of the present study report the left–right distribution of infarcts in their study? Have they found a preponderance of unrecognized infarcts in the right side of the brain? If so, then physicians and patients need help recognizing these nondominant strokes in order to optimize acute treatments but also to recognize impairments that may be important but subtle.
1 ReferencesThomas E. Finucane, M.D.
Johns Hopkins Bayview Medical Center, Baltimore, MD 21224
tfinucan@jhmi.edu 1
Foerch C ,Misselwitz B ,Sitzer M , et al. Difference in recognition of right and left hemisphere stroke. Lancet 2005;366:392-393
CrossRef | Web of Science | Medline
Author/Editor Response
We agree with Rocque and colleagues that in the absence of information on the natural history of incidental findings, the optimal management should be based on the best available evidence. We therefore referred all persons with MRI findings consistent with meningiomas and pituitary adenomas to an appropriate specialist. However, because the majority of probable meningiomas were small (83% were ≤2 cm), which is similar to observations made in autopsy studies,1 we believe that referral of all persons with incidental findings suggestive of meningiomas may possibly be unwarranted. Regarding small unruptured aneurysms, the ISUIA2 currently provides, in our view, the best prospective data to guide management. The risk of rupture for aneurysms that are less than 7 mm in the anterior circulation was 0%,2 and in persons over the age of 40 years, the risks associated with treatment of these aneurysms were found to outweigh the benefits.3 We like to emphasize that patients included in the ISUIA were selected because of the known presence of an unruptured aneurysm. They might have presented with aneurysmal symptoms other than rupture, might have had a previous ruptured aneurysm, or might have had a positive family history — all known risk factors for rupture. The risk of rupture in our series of persons without a clinical indication for undergoing brain imaging is likely to be even lower. Therefore, we decided not to refer these persons. However, should new evidence become available in support of a different approach, we intend to adjust our protocol accordingly.
With regard to the incidental findings in a Chinese population in Taiwan, presented by Lee and colleagues, we agree with them that the lower prevalence of aneurysms and asymptomatic infarcts in their population as compared with ours might be explained by a combination of factors — most notably, the younger mean age of their study participants, but possibly also the population's different ethnic composition and differences in the scanning protocol. We strongly support the performance of similar studies of prevalence rates of incidental brain findings, to further augment knowledge in this area.
Finucane raises an interesting question about the left–right hemispheric distribution of asymptomatic strokes, since it has been hypothesized that these strokes may predominantly be right-sided.4 Among the 145 persons with asymptomatic stroke in our population, 35 had only cerebellar infarcts (30) or brain-stem infarcts (5). There were 19 persons who had bilateral hemispheric infarcts. Among the 91 persons who had unilateral asymptomatic stroke, 39 (43%) had right-sided lesions, and 52 (57%) had left-sided lesions. This difference was not significant and furthermore does not seem to support the aforementioned hypothesis.
4 ReferencesMeike W. Vernooij, M.D.
Monique M.B. Breteler, M.D.
Aad van der Lugt, M.D.
Erasmus University Medical Center, 3015 CE Rotterdam, the Netherlands
a.vanderlugt@erasmusmc. nl 1
Nakasu S ,Hirano A ,Shimura T ,Llena JF . Incidental meningiomas in autopsy study. Surg Neurol 1987;27:319-322
CrossRef | Web of Science | Medline2
Wiebers DO ,Whisnant JP ,Huston J III , et al. Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment. Lancet 2003;362:103-110
CrossRef | Web of Science | Medline3
Takao H ,Nojo T . Treatment of unruptured intracranial aneurysms: decision and cost-effectiveness analysis. Radiology 2007;244:755-766
CrossRef | Web of Science | Medline4
Brott T ,Tomsick T ,Feinberg W , et al. Baseline silent cerebral infarction in the Asymptomatic Carotid Atherosclerosis Study. Stroke 1994;25:1122-1129
CrossRef | Web of Science | Medline
- Citing Articles (5)
Citing Articles
1
Ronald J.H. Borra, A. Gregory Sorensen. (2011) Incidental Findings in Brain MRI Research: What Do We Owe Our Subjects?. Journal of the American College of Radiology 8:12, 848-852
CrossRef2
Wajd N. Al-Holou, Adam Khan, Thomas J. Wilson, William R. Stetler, Gaurang V. Shah, Cormac O. Maher. (2011) Incidental findings on cranial imaging in nonagenarians. Neurosurgical Focus 31:6, 1-6
CrossRef3
Shivanand P. Lad, Larry Shannon, Richard W. Byrne. (2011) Incidental aneurysms in temporal lobe epilepsy surgery: report of three cases and a review of the literature. British Journal of Neurosurgery1-6
CrossRef4
Randolph W. Evans, James C. Johnston. (2011) Migraine and Medical Malpractice. Headache: The Journal of Head and Face Pain 51:3, 434-440
CrossRef5
Tae Yeon Jeon, Pyoung Jeon, Keon Ha Kim. (2011) Prevalence of Unruptured Intracranial Aneurysm on MR Angiography. Korean Journal of Radiology 12:5, 547
CrossRef
