Evaluation of the Effect of Hemoglobin or Hematocrit Level on Dural Sinus Density Using Unenhanced Computed Tomography

PURPOSE: To identify the relationship between hemoglobin (Hgb) or hematocrit (Hct) level and dural sinus density using unenhanced computed tomography (UECT). MATERIALS AND METHODS: Patients who were performed UECT and had records of a complete blood count within 24 hours from UECT were included (n=122). We measured the Hounsfield unit (HU) of the dural sinus at the right sigmoid sinus, left sigmoid sinus and 2 points of the superior sagittal sinus. Quantitative measurement of dural sinus density using the circle regions of interest (ROI) method was calculated as average ROI values at 3 or 4 points. Simple regression analysis was used to evaluate the correlation between mean HU and Hgb or mean HU and Hct. RESULTS: The mean densities of the dural sinuses ranged from 24.67 to 53.67 HU (mean, 43.28 HU). There was a strong correlation between mean density and Hgb level (r=0.832) and between mean density and Hct level (r=0.840). CONCLUSION: Dural sinus density on UECT is closely related to Hgb and Hct levels. Therefore, the Hgb or Hct levels can be used to determine whether the dural sinus density is within the normal range or pathological conditions such as venous thrombosis.

Variations in the cerebral venous anatomy and pitfalls in the diagnosis of cerebral venous sinus thrombosis: low field MR experience.

BACKGROUND: Knowledge of variations in the cerebral venous anatomy and apparent signal abnormalities seen on Magnetic resonance (MR) angiography are essential to avoid over-diagnosis of cerebral venous sinus thrombosis (CVST), while interpreting the MR angiograms. AIMS: To evaluate the variations of cerebral venous anatomy and signal abnormalities by using 3D phase contrast MR angiography performed in a 0.5 Tesla MRI scanner. MATERIALS AND METHODS: One hundred patients who underwent MR imaging and MR angiography examinations at our institution from March 2004 to February 2005, with normal MR imaging of brain were studied retrospectively. Patients with clinical suspicion of CVST and patients who underwent color doppler evaluation for suspected deep vein thrombosis were excluded. RESULTS: The superior sagittal, straight sinus and the internal cerebral veins were visualized in all patients. There was hypoplasia of the right transverse sinus in 13 patients, left transverse sinus in 35 patients, right sigmoid sinus in 6 patients and left sigmoid sinus in 19 patients. Absence of transverse sinus on left side was observed in one patient and absence of sigmoid sinus in 2 patients on left side. Flow gaps were observed in non-dominant transverse sinus, sigmoid sinus as well as transverse sigmoid sinus junctions. The occipital sinus was visualized in 17 patients. CONCLUSIONS: MR angiography done at low field strengths is also a reliable method, for assessing cerebral venous sinuses. Awareness of the normal anatomical variations of venous sinuses and apparent MR angiographic flow gaps prevent misdiagnosis of cerebral venous sinus thrombosis.

The Experience of Ligation of Transverse or Sigmoid Sinus in Surgery of Large Petroclival Meningiomas

The authors present the experience of ligation of transverse or sigmoid sinus in the surgical removal of petroclival meningiomas. We reviewed the medical records and venograms of 14 patients with petroclival meningiomas, in whom the intraoperative ligation of transverse or sigmoid sinus had been done at our hospital between 1986 and 1999. All patients passed the intraoperative test clamping of the sinus. The drainage pattern of confluence of Herophili was classified into four types: type A, confluence and equal drainage on both transverse sinuses; type B, confluence and non-dominant transverse sinus on the tumor side; type C, confluence and dominant transverse sinus on the tumor side; and type D, unilateral transverse sinus only. Among the 14 cases, four cases were in type A, five cases in type B, and two were type C. There was no evidence of brain swelling after intraoperative test clamping of the sinus for more than 30 min. None of the patients experienced postoperative complications related with sinus ligation. Our observation suggests that the transverse or sigmoid sinus ligation is tolerable to patients sinus. who show the drainage patterns of type A, type B, and type C, if the test clamping proves to be safe.