Acoustic neuroma CT
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Acoustic neuroma Microchapters | |
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Acoustic neuroma CT On the Web | |
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American Roentgen Ray Society Images of Acoustic neuroma CT | |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [3]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [4]
Overview
Head CT scan may be diagnostic of acoustic neuroma. Findings on CT scan diagnostic of acoustic neuroma include erosion, and widening of the internal acoustic canal.
CT
- CT scans with bone windows can also be of prognostic significance as the extent of widening of the IAC and the extent of tumor growth anterior and caudal to the IAC are predictive of postoperative hearing loss.[1]
- Meanwhile the procedure of choice for diagnosing of acoustic neuroma is gadolinium-enhance magnetic resonance imaging (MRI), but if MRI cannot be done on patient, high resolution CT scanning with and without contrast is an alternative.
- On MRI and CT scans, vestibular schwannoma can be seen as enhancing lesions in the region of the internal auditory canal with variable extension into the cerebellopontine angle.[2]
- CT scans with bone windows can also be of prognostic significance.
- CT may show erosion and widening of the internal acoustic canal.
- The density of these tumors on non-contrast imaging is variable, and often they are hard to see, especially on account of beam hardening and streak artifact form the adjacent petrous temporal bone.
- Contrast enhancement is present, but can be underwhelming, especially in larger lesions with cystic components.
- Well-performed scanning can demonstrate tumors 1-2 mm in diameter. However, even with intravenous contrast enhancement thin-cut CT scanning can miss tumors as large as 1.5 cm even.
- Fine-cut CT scanning of the internal auditory canal with contrast can detect medium-size or large tumor but are not reliable imaging techniques to detect a tumor smaller than 1-1.5 cm.
Differentiating Acoustic Neuroma from Meningioma in CT Scans
The most important differential diagnosis for Acoustic neuroma is Meningioma of Pontine angle, so it is vital to distinguish these two diseases. As you see below this diagram demonstrate this differences of these two disease in CT Scan.[5]
| <13cm3 | Volume | >35cm3 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| No | Increased attenuation | Yes | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| No | Marked calcification | Yes | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| No | Oval shape | Yes | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Yes | Round shape | Mostly No | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Acoustic Neuroma | No | Tumor reaches dorsum sellae anteriorly | Yes | Meningioma | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mostly No | Apparently broad attachment to bone | Yes | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| No | Center of tumor anterior to porus | Sometimes Yes | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| No | Tumor reaches > 2 cm above dorsum | Mostly Yes | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Sometimes | Peripheral edema | No | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mostly Yes | Widening of porus or other bone changes | No | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
References
- ↑ C. Matthies, M. Samii & S. Krebs (1997). "Management of vestibular schwannomas (acoustic neuromas): radiological features in 202 cases--their value for diagnosis and their predictive importance". Neurosurgery. 40 (3): 469–481. PMID 9055285. Unknown parameter
|month=ignored (help) - ↑ C. Matthies, M. Samii & S. Krebs (1997). "Management of vestibular schwannomas (acoustic neuromas): radiological features in 202 cases--their value for diagnosis and their predictive importance". Neurosurgery. 40 (3): 469–481. PMID 9055285. Unknown parameter
|month=ignored (help) - ↑ Image courtesy of Dr Frank Gaillard. Radiopaedia (original file [1]).[http://radiopaedia.org/licence Creative Commons BY-SA-NC
- ↑ Image courtesy of Dr Prashant Mudgal. Radiopaedia (original file [2]).[http://radiopaedia.org/licence Creative Commons BY-SA-NC
- ↑ A. M611er, A. Hatam and H. Olivecrona (1978). "The Differential Diagnosis of Pontine Angle Meningioma and Acoustic Neuroma with Computed Tomography". Neuroradilogy.