Elsevier

Clinical Imaging

Volume 37, Issue 5, September–October 2013, Pages 865-870
Clinical Imaging

Original Article
The anatomical classification of AICA/PICA branching and configurations in the cerebellopontine angle area on 3D-drive thin slice T2WI MRI

https://doi.org/10.1016/j.clinimag.2011.11.021Get rights and content

Abstract

Background

With the technical advance of magnetic resonance imaging (MRI), we have been able to observe not only the small cranial nerves arising from the brain stem but also the branches of vertebrobasilar artery in the cerebellopontine angle (CPA) cistern.

Purpose

The purpose was to demonstrate the courses and configurations of the anterior inferior cerebellar artery (AICA) or posterior inferior cerebellar artery (PICA) branch including the internal auditory artery in the CPA cistern and evaluate the relationship between the facial–vestibulocochlear (VIIth–VIIIth) nerves and AICA/PICA on high-resolution, thin-slice, three-dimensional T2-weighted MRI using driven equilibrium pulse.

Material and methods

Thirty-three men and 27 women aged 8–85 years old with sensory hearing loss or vertigo, and/or tinnitus were evaluated by thin-slice (0.75 mm) T2-weighted MRI. Five subjects (3 men, 2 women) without any auditory symptoms were also examined.

Results

Thin-slice T2WI drive MRI revealed several variations of the AICA/PICA coursing, such as a loop formation (n=30, 48 sides) or the IAC extension (n=19, 30 sides). Contact with the vestibulocochlear nerve was seen in 31.7% subjects (n=19, 27 sides). The AICA/PICA branching and shape patterns relative to the CPA and IAC were classified into four major types: type 1A, nonloop AICA/PICA in the CPA cistern; type 1 B, nonloop AICA/PICA (internal auditory artery) entering the IAC; type 2A, loop-type AICA/PICA in the CPA cistern; and type 2B, loop-type AICA/PICA entering the IAC.

Conclusion

There was statistically significant association between types 1A and 2A (P<.01) regarding the existence of any auditory 3 symptoms. The results of our study suggest that this classification is simple and very useful for the elucidation of the mechanism of auditory symptoms and deciding the therapeutic strategies.

Section snippets

Material and methods

From September 2006 to August 2011,a total of 60 consecutive patients (33 men and 27 women aged 8–85 years old; mean age 53.4 years old) with sensory hearing loss or vertigo, dizziness, and/or tinnitus were examined with 1.5-T Intera Achieva MRI scanner with sense coil (Philips Medical System, Best, the Netherlands). Five subjects (three men, two women) without any auditory symptoms were also included in this study. On each subject, the informed consent was obtained. Our institutional ethics

Results

In this study, three acoustic schwannomas (size ranging from 3 mm to 28×25×24 mm) were detected in the IAC or CPA cistern in three patients. Cochlear abnormality such as bilateral hypoplastic anomaly of the inner ear was observed in a 60 year-old female patient with deafness. The dilatation of vestibular aqueduct was also seen in a hearing loss case (Fig. 1). The brain stem lacuna infarction and chronic ischemic foci were observed in two and one case(s), respectively. We also encountered the

Discussion

MRI including an enhanced study with Gd-DTPA has been used commonly to rule out the acoustic tumor or other active inflammatory lesions such as Ramsay–Hunt syndrome or labyrinthitis in patients with auditory symptoms. Especially in patients with sensory neural hearing loss, MRI is superior to computed tomography in evaluating the inner ear, blood vessels, adjacent fatty bone marrow, and cerebrospinal fluid (CSF) spaces because of its superior characterization of soft tissue. MRI is also useful

References (24)

  • MB Moller et al.

    Vascular decompression surgery for severe tinnitus :selection criteria and results

    Laryngoscope

    (1993)
  • S Naganawa et al.

    High-resolution T2-weighted MR imaging of the inner ear using a long echo-train-length 3D fast spin echo sequence

    Eur Radiolo

    (1996)
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