The Gibraltar Sign: An Anatomic Landmark for Predicting Transverse Sinus Dominance Laterality on Conventional MRI

Can occipital lobe bending, Gibraltar sign of superior sagittal sinus groove and jugular foramen dimensions predict transverse sinus dominance?

BACKGROUND

Asymmetry between the transverse sinuses (TS) is quite common. We sought to test the possible hypothesis that certain anatomical features - namely, occipital lobe bending, Gibraltar sign of superior sagittal sinus groove (SSS) and jugular foramen (JF) dimensions - can predict dominance of the transverse sinuses on routine axial T1- and T2-weighted images.

MATERIALS AND METHODS

One hundred consecutively acquired combined MRI-MRV studies of brain were reviewed. On non-contrast axial T1WI, each reviewer assessed the occipital lobe bending, and Gibraltar sign of SSS groove; on axial T2-weighted images, JF dimensions were measured. TS cross-sectional area was measured on non-contrast sagittal 2-dimensional phase contrast MRV images and served as the reference standard.

RESULTS

Of the 51 subjects with right-dominant TS, 37 had occipital bending to the right side and 35 showed sloping of the Gibraltar sign to right side. Of the 18 subjects with left dominant TS, 10 had occipital bending to left side and 13 showed left-sided sloping of the Gibraltar sign. Of the 31 subjects with co-dominant TS, 15 had no occipital bending and 20 showed no sloping of the Gibraltar sign. Mean right and left JF dimensions were higher in the right and left dominant TS respectively with no significant differences in patients with co-dominant sinus (p < 0.02).

CONCLUSION

Right occipital bending had a good association with right TS dominance. The other two parameters- Gibraltar sign of superior sagittal sinus groove and jugular foramen dimensions - did not have a very good association with respect to TS dominance.

High-Resolution Magnetic Resonance Black Blood Thrombus Imaging and Serum D-Dimer in the Confirmation of Acute Cortical Vein Thrombosis

Cerebral cortical vein thrombosis (CCVT) is often misdiagnosed because of its non-specific diagnostic symptoms. Here, we analyzed a cohort of patients with CCVT in hopes of improving understandings and treatments of the disease. A total of 23 patients with CCVT (confirmed with high-resolution imaging), who had been diagnosed between 2017 and 2019, were enrolled in this cohort study. Baseline demographics, clinical manifestations, laboratory data, radiological findings, treatment, and outcomes were collected and analyzed. Fourteen females and nine males were enrolled (mean age: 32.7 ± 11.9 years), presenting in the acute (within 7 days, n = 9), subacute (8–30 days, n = 7), and chronic (over 1 month, n = 7) stages. Headaches (65.2%) and seizures (39.1%) were the most common symptoms. Abnormally elevated plasma D-dimers were observed in the majority of acute stage patients (87.5%). The diagnostic accuracy of contrast-enhanced magnetic resonance venography (CE-MRV) and high-resolution magnetic resonance black-blood thrombus imaging (HR-MRBTI) in detecting CCVT were 57.1 and 100.0%, respectively. All patients had good functional outcomes after 6-month of standard anticoagulation (mRS 0–1) treatment. However, four CCVT patients that had cases involving multiple veins showed symptom relief after batroxobin therapy (p = 0.030). HR-MRBTI may be a fast and accurate tool for non-invasive CCVT diagnosis. HR-MRBTI combined with D-dimer can also precisely identify the pathological stage of CCVT. Batroxobin may safely accelerate cortical venous recanalization in combination with anticoagulation. Follow-up studies with larger sample sizes are suggested to evaluate the safety and efficacy of batroxobin for treating CCVT.

Occipital petalia as a predictive imaging sign for transverse sinus dominance

OBJECTIVES

Occipital petalia is an anatomic description where one of the occipital lobes protrudes towards the contralateral side. Transverse sinus (TS) asymmetry might cause diagnostic challenges with regards to thrombotic or compressive pathologies involving these sinuses. In this study, we investigated the association between occipital petalia and TS hypoplasia on MRI studies.

METHODS

In 264 subjects with no neurological complaints, occipital bending was determined on T1-weighted images based on the angulation of interhemispheric fissure between occipital lobes with respect to an imaginary midline. TS asymmetry was evaluated visually. Information on handedness and ocular dominance was also gathered from all participants.

RESULTS

Rightwards bending was observed in 72 subjects (27%), whereas leftwards bending was present in only 10 participants (4%). The presence or direction of bending was related neither to hand nor ocular dominance. In participants with rightwards bending, 72% had a larger TS on the right-side, while only a single subject had a left-sided predilection for venous drainage. In subjects with leftwards bending, 70% had a left-dominant TS drainage system and none had a larger TS on the right. Overall, the direction of bending was predictive of TS dominance on the ipsilateral side with a PPV of 72% (95%CI, 60-82%) for right and 70% (95%CI, 35-92%) for left.

DISCUSSION

The direction of bending, a relatively straightforward radiologic diagnosis, is closely linked to the side of TS hypoplasia, and thereby might provide physicians with an additional diagnostic clue regarding the interpretation of imaging findings related to TSs and their pathologies.