Preoperative Evaluation of Venous Systems With Computed Tomography Venography in Parasagittal Meningiomas:

Evaluation of parenchymal collaterals in patients with meningioma using contrast-enhanced T1 MPRAGE sequence

BACKGROUND

Post-contrast T1-MPRAGE sequence has been used in routine tumor imaging at many centers for decades. Meningiomas may be accompanied by leptomeningeal as well as parenchymal collaterals. In this study, we aimed to demonstrate the collaterals that may accompany meningiomas on postcontrast T1-MPRAGE imaging and to investigate their relationship with location, size, histologic features, adjacent bone, and parenchymal changes.

METHODS

In this study, postcontrast T1-MPRAGE images of 326 meningiomas from 259 patients were independently analyzed by two observers. The presence of parenchymal collaterals and unilateral, contralateral or bilateral localization were determined. Meningiomas' diameters, locations, presence of dural sinus invasion, associated parenchymal changes and bony changes were determined. Histologic grades were determined if applicable. The data obtained were analyzed statistically.

RESULTS

Parenchymal collaterals were demonstrated in 25% of meningiomas (66/259). Of these, 65% were unilateral, 12% contralateral and 23% bilateral. There was a significant correlation between malignancy and the presence of collaterals in histologically diagnosed meningiomas (77%, p = 0.01). The presence of collaterals was also significantly higher in meningiomas with sinus invasion and bone destruction (p < 0.001). As tumor size increased, unilateral and bilateral collateral development increased (p < 0.001, p = 0.008, respectively), but it was not significant in contralateral cases. There was significant concordance between the observers in terms of the presence of collaterals (kappa: 0.773).

CONCLUSIONS

Meningiomas may be accompanied by parenchymal collaterals. WHO grade 3 histologic type, sinus invasion, bone destruction and size increase are predictors of collateral development.

Comment on "Route patterns of the collateral venous pathway in patients with tumors invading the superior sagittal sinus: an angiographic study and clinical applications"

This commentary critiques the study "Route patterns of the collateral venous pathway in patients with tumors invading the superior sagittal sinus" by Pawit Jirawisan et al., highlighting its limitations in discussing parafalcine venous collaterals, reliance on invasive imaging modalities, and lack of structured assessments. It suggests improvements by incorporating alternative imaging techniques, acknowledging crucial venous structures, and providing grading systems for surgical decision-making.

3D digital subtracted CT angiography to evaluate the venous anatomy in extra-axial tumors invading the major dural venous sinuses

Background Investigation of the venous system surrounding a tumor that is invading a dural sinus is of great use for guiding the surgical excision. Non-invasive imaging is often inadequate since enhancement of the tumor causes it to blend with the contrast of the venous vascular structures. Conventional two-dimensional angiography is also often insufficient. Objective The objective of this study was to report regarding the potential of three-dimensional digital subtracted computed tomography angiography (3D DS-CTA) as a technique to preoperatively explore these tumors. Methods We retrospectively studied the radiological and surgical features of patients explored with 3D DS-CTA for a tumor invading a major dural sinus. Results Three patients were included in this study, one hemangiopericytoma and two meningiomas. 3D DS-CTA allows for accurate assessment of the patency of the sinus, the location of the secondary intra- and trans-osseous venous outlets, and surgical guidance by neuronavigation. Conclusion 3D DS-CTA could be a promising guiding and diagnostic tool for the pre- and intraoperative treatment of vascular tumors invading the dural sinuses, for which the venous morbidity and mortality is substantial.

Usefulness of 4D-CTA in the detection of cerebral dural sinus occlusion or stenosis with collateral pathways

In time-resolved CT angiography (4D-CTA), it is of substantial merit to detect the veins and sinuses of the whole brain with the simultaneous demonstration of the natural drainage flow in order to find occlusion or stenosis of the dural sinuses with collateral pathways. As preoperative information for patients with brain tumors, it is important to detect feeding arteries, incidentally found aneurysms or other vascular lesions, and to detect patency of the dural sinuses and the important cortical veins, whether they are compressed by tumors or not. On the other hand, cerebral venous thrombosis (CVT) may occur in patients due to various causes, which has not been unusual in recent years. For patients with acute symptomatic or chronic non-symptomatic CVT, identification of dural sinus occlusion (DSO) or dural sinus stenosis (DSS) and compensatory collateral pathways is necessary for suitable thrombolytic therapy or careful investigation to avoid further CVT. This study reviews our experiences in 116 cases of 4D-CTA for 90 patients with brain tumors and 26 other patients including 11 with arteriovenous malformation, and four with acute CVT and other conditions. 4D-CTA presented DSO/DSS with compensatory venous collateral pathways, which was helpful to detect the severity of the venous abnormality, and see whether it was compressed by brain tumors, or due to other causes in patients with symptomatic or non-symptomatic CVT. 4D-CTA is a useful non-invasive diagnostic tool to detect cerebral venous abnormalities as an alternative to DSA.

Indocyanine green (ICG) temporary clipping test to assess collateral circulation before venous sacrifice

BACKGROUND

As a general principle, sacrifice of cerebral veins at surgery is avoided. However, at times sacrifice of a vein may be desirable to increase surgical exposure. At present, no method exists to predict whether such sacrifice will be accommodated by the presence of collateral venous drainage. We show a simple technique to examine cerebral venous blood flow using indocyanine green videoangiography.

METHODS

In two patients, parasagittal meningiomas were found to be associated with paramedian veins that impeded complete removal of the tumors. The suitability of veins removal was assessed by applying a temporary aneurysm clip and performing an indocyanine green videoangiogram.

RESULTS

In one patient, stasis was observed in the vein. In the second patient, a collateral flow allowed the venous blood to drain. The former test was considered a counterindication for venous sacrifice, whereas the latter supported its feasibility. The vein was preserved in the former case and coagulated in the latter. In both cases, the patients did well.

CONCLUSIONS

Although our limited study cannot prove that venous congestion or infarction can be avoided with this technique, it does provide direct evidence of the presence or absence of collaterals that can help guide intraoperative surgical decision-making.

Venous sacrifice in neurosurgery: new insights from venous indocyanine green videoangiography

OBJECT

The purpose of this paper is to evaluate whether venous indocyanine green (ICG) videoangiography has any potential for predicting the presence of a safe collateral circulation for veins that are at risk for intentional or unintentional damage during surgery.

METHODS

The authors performed venous ICG videoangiography during 153 consecutive neurosurgical procedures. On those occasions in which a venous sacrifice occurred during surgery, whether that sacrifice was preplanned (intended) or unintended, venous ICG videoangiography was repeated so as to allow us to study the effect of venous sacrifice. A specific test to predict the presence of venous collateral circulation was also applied in 8 of these cases.

RESULTS

Venous ICG videoangiography allowed for an intraoperative real-time flow assessment of the exposed veins with excellent image quality and resolution in all cases. The veins observed in this study were found to be extremely different with respect to flow dynamics and could be divided in 3 groups: 1) arterialized veins; 2) fast-draining veins with uniform filling and clear flow direction; and 3) slow-draining veins with nonuniform filling. Temporary clipping was found to be a simple and reversible way to test for the presence of potential anastomotic circulation.

CONCLUSIONS

Venous ICG videoangiography is able to reveal substantial variability in the venous flow dynamics. "Slow veins," when they are tributaries of bridging veins, might hide a potential for anastomotic circulation that deserve further investigation.