Arachnoid granulations in the transverse and sigmoid sinuses: CT, MR, and MR angiographic appearance of a normal anatomic variation

To investigate the imaging characteristics, prevalence, and clinical significance of arachnoid granulations in the transverse and sigmoid venous sinuses. We reviewed the imaging findings, clinical signs and symptoms, final diagnoses, and follow-up studies of 32 patients with 41 probable arachnoid gr...

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Bibliographic Details
Published in:American journal of neuroradiology : AJNR 1996-04, Vol.17 (4), p.677-683
Main Authors: Roche, J, Warner, D
Format: Article
Language:English
Subjects:
Adult
Aged
Anatomy
Arachnoid - pathology
Biological and medical sciences
Central nervous system
Comparative Study
Cranial Sinuses - pathology
Female
Follow-Up Studies
Fundamental and applied biological sciences. Psychology
Granulation Tissue - pathology
Humans
Magnetic Resonance Angiography
Magnetic Resonance Imaging
Male
Middle Aged
Reference Values
Tomography, X-Ray Computed
Vertebrates: nervous system and sense organs
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Summary:To investigate the imaging characteristics, prevalence, and clinical significance of arachnoid granulations in the transverse and sigmoid venous sinuses. We reviewed the imaging findings, clinical signs and symptoms, final diagnoses, and follow-up studies of 32 patients with 41 probable arachnoid granulations. On CT scans, arachnoid granulations appear as well-defined filling defects, wholly or partly within a venous sinus, with the same density as cerebrospinal fluid. MR images show these entities as largely isointense with cerebrospinal fluid in all sequences. Linear variations of signal intensity within the granulations are thought to be fibrous septa or vessels. Calcification was present in 3 granulations and altered both CT density and MR signal intensity. The granulations appear as filling defects at MR angiography and at digital subtraction angiography. In some oblique MR angiographic projections, they appear elliptical and could be mistaken for thrombus. No clinical significance could be given to the existence of any of these arachnoid granulations. They occur in 0.3 to 1 of 100 adults in the population. Arachnoid granulations in the transverse and sigmoid venous sinuses are common findings seen with thin-section imaging and are usually of no significance.
ISSN:0195-6108
1936-959X