In vitro comparison of water displacement method and 3 Tesla MRI for MR-volumetry of the olfactory bulb: which sequence is appropriate?

Visualization of the periventricular Virchow-Robin spaces with ependymal openings

PURPOSE

The morphological relationships between the periventricular Virchow-Robin spaces (VRSs) and cerebral ventricles have been poorly documented. The present study aimed to explore the issue using magnetic resonance imaging.

METHODS

A total of 211 patients were included in this study. T2-weighted and constructive interference in steady state (CISS) sequences were performed in thin-sliced, coronal sections.

RESULTS

On T2-weighted sequence, the periventricular VRSs with ependymal openings were identified in 34% of 139 subjects. All the openings were located in the lateral wall of the anterior horn. In CISS sequences, such VRSs were found in 39% of 72 subjects. The mean age was significantly higher in the population with such VRSs compared to those without VRSs (p = 0.0047). Of the 58 periventricular VRSs with ependymal openings identified on T2-weighted images, 16% were located in the upper, 36% in the middle, and 48% in the lower part of the lateral wall. Of the 38 such VRSs identified on CISS images, 32% were located in the upper, 24% in the middle, and 42% in the lower part of the lateral wall, and 3% in the upper part of the medial wall.

CONCLUSIONS

The ependymal openings of the periventricular VRSs may be centered in the lateral wall of the anterior horn. The coronal CISS sequence can sensitively delineate the VRSs with ependymal openings.

The cisternal segment of the anterior choroidal artery: an anatomical study using magnetic resonance imaging

PURPOSE

The topography of the anterior choroidal artery (AChA) has infrequently been delineated on neuroimages. The present study aimed to explore the cisternal segment of the AChA using magnetic resonance imaging.

METHODS

A total of 50 sides of the AChA obtained from 25 patients were included in this study. A constructive interference in steady-state (CISS) sequence was performed in thin-sliced axial sections. Furthermore, the cisternal AChA and relevant neurovascular structures were observed through cadaveric dissections in two heads.

RESULTS

In the cadaveric dissections, all the AChAs were exposed only in the proximal part even after extensive arachnoid dissections and cerebral retraction. In the examinations with the CISS sequence, the original site of the AChA was identified on the right side in 88% and on the left side in 96%. In 70% of the 50 sides, the AChA arose from the posterolateral wall of the internal carotid artery, distally to that of the posterior communicating artery. The cisternal course of the AChA was delineated on the right side in 96% and on the left side in 100%; it crossed over the optic tract in variable manners with the middle third as the most frequent site found in 60% of the sides.

CONCLUSIONS

The cisternal AChA shows a morphological variability. The CISS sequence is useful for delineating the cisternal AChA.

The third ventricle roof: an anatomical study using constructive interference in steady-state magnetic resonance imaging

PURPOSE

The third ventricle roof in vivo has been infrequently explored. The aim of the present study was to delineate the neurovascular structures relevant to the third ventricle roof using magnetic resonance (MR) imaging.

METHODS

A total of 78 patients were enrolled in the study. Following initial examinations with conventional MR sequences, the constructive interference in steady-state (CISS) sequence was performed in coronal sections on 67 patients and in sagittal sections on 11 patients.

RESULTS

In the coronal sections, the fornices and internal cerebral veins were delineated in all 67 patients. The cross-sectional appearance and size of the fornices were variable, and the relationship between fornices presented as five different types. In 82% of patients, dominance of one relationship type was not found. The diameter of the internal cerebral veins (ICVs) was also variable, and the relationship between ICVs presented as four different types. In 70% of patients, dominance of one relationship type was not found. In 52% of patients, the lower layer of the third ventricle roof was identified as an inhomogeneous membranous structure. In the sagittal sections, the lower layer of the third ventricle roof was delineated as an inhomogeneous linear structure with variable slopes.

CONCLUSIONS

The third ventricle roof appears highly variable in morphology. Visualization of the third ventricle roof using the CISS sequence may be useful for planning safe and effective surgical maneuvers around the region.

The suprapineal recess of the third ventricle: an anatomic study with magnetic resonance imaging

PURPOSE

The suprapineal recess (SPR) is a small, backward extension of the third ventricle. Few radiological studies have investigated the morphology of the SPR. Here, we explore the SPR with magnetic resonance (MR) imaging.

METHODS

A total of 124 patients underwent thin-slice MR imaging examinations with T2-weighted imaging and the constructive interference steady-state (CISS) sequence. Imaging data were transferred to a workstation for analysis.

RESULTS

The pineal gland (P) was delineated in 99% of the patients on T2-weighted imaging and 100% of the patients on the CISS sequence. In contrast, the SPR was identified in 27% of the patients on T2-weighted imaging and 82% of the patients on the CISS sequence. The location of the P relative to the lowest point of the splenium was roughly classified into two types. Of them, the anterior P location was the more frequent type and observed in 73% of the patients. The angle formed by the roof and floor of the SPR showed remarkable interindividual diversity. A membranous posterior extension with variable length, spanning between the posterosuperior margin of the P and Galenic complex was found in 55% of the identified SPRs on T2-weighted imaging and 45% on the CISS sequence.

CONCLUSIONS

The SPR is a distinct structure with diversity in appearance among individuals but commonly extends posterior to the P. High-resolution MR imaging is useful for delineating the SPR in vivo.