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Small, patent cerebral aneurysms: atypical appearances at 1.5-T MR imaging
1Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT 06520-8042, USA.
Purpose:
To determine the frequency and characteristics of small cerebral aneurysms with atypical appearances on magnetic resonance (MR) images.
Materials And Methods:
MR imaging studies (n = 117) obtained at 1.5 T of small aneurysms (< 1 cm diameter) were prospectively and retrospectively analyzed. Signal intensity characteristics and gadolinium-enhancement patterns in 84 aneurysms (62 patients) were evaluated. The patency of all aneurysms was confirmed at angiography or at the time of surgery.
Results:
A characteristic signal void was seen on 62 (53%) of 117 studies. On the remaining 55 (47%) studies, aneurysms had atypical signal intensity that was isointense, heterogeneous, or hyperintense. Contrast-enhanced aneurysms were seen on 27 (53%) of 51 gadolinium-enhanced studies.
Conclusion:
Atypical MR imaging characteristics were seen in roughly half of cases. These atypical-appearing aneurysms may erroneously be considered to be thrombosed or be mistaken for other common lesions such as small tumors and be dismissed as nonvascular.
Insights
Roughly half of small cerebral aneurysms (< 1 cm) show atypical magnetic resonance (MR) imaging features. These unusual appearances can lead to misdiagnosis, potentially overlooking these vascular lesions.
Area of Science:
- Neuroradiology
- Medical Imaging
Background:
- Small cerebral aneurysms (< 1 cm) can present diagnostic challenges on magnetic resonance (MR) imaging.
- Atypical appearances may lead to misinterpretation as thrombosed lesions or other nonvascular abnormalities.
Purpose of the Study:
- To investigate the frequency and specific characteristics of small cerebral aneurysms exhibiting atypical appearances on MR imaging.
Main Methods:
- Analysis of 117 MR imaging studies (1.5 T) of small cerebral aneurysms.
- Evaluation of signal intensity and gadolinium-enhancement patterns in 84 aneurysms from 62 patients.
- Confirmation of aneurysm patency through angiography or surgical findings.
Main Results:
- A typical signal void was observed in 53% of studies.
- Atypical signal intensities (isointense, heterogeneous, hyperintense) were noted in 47% of cases.
- Contrast enhancement was present in 53% of evaluated gadolinium-enhanced studies.
Conclusions:
- Approximately 50% of small cerebral aneurysms demonstrate atypical MR imaging features.
- These atypical characteristics can result in misclassification as thrombosed aneurysms or nonvascular lesions.
- Awareness of these atypical findings is crucial for accurate diagnosis and management.