Sinuses and veins detectable by ultrasound: 1, deep middle cerebral vein; 2, middle cerebral artery; 3, anterior cerebral artery; 4, posterior cerebral artery; 5, basal vein of Rosenthal; 6, vein of Galen; 7, sphenoparietal sinus; 8, superior petrosal sinus; 9, cavernous sinus; 10, inferior petrosal sinus; 11, cerebellar tentorium; 12, transverse sinus; 13, straight sinus.
The deep middle cerebral vein (DMCV) is found adjacent to the middle cerebral artery and drains into the basal vein (BV), which follows the course of the posterior cerebral artery around the mesencephalon and joins the contralateral BV in the great cerebral vein (GCV) of Galen in the midline behind the pineal gland. The straight sinus (SRS) runs in the apex of the cerebellar tentorium and connects the GCV with the confluens sinuum. The rostral part of the superior sagittal sinus joins the confluens and from there the transverse sinus (TS) takes a course underneath the occipital bone to eventually form the sigmoid sinus and drain into the internal jugular vein. The two major contributories to the cavernous sinus which can be insonated are the sphenoparietal sinus (SPhPS) in the lesser and the superior petrosal sinus in the major wing of the sphenoid bone. The inferior petrosal sinus and parts of the vertebral venous plexus lie in close anatomical relationship to the basilar artery.
Imaging tips
Unable to see any veins?
Normal venous flow velocities are low. As a consequence, a low-flow sensitive color program with a low wall filter setting is necessary for TCCS. Sometimes you need to try out different color programs together with a service technician. The pulse repetition frequency (PRF) needs to be reduced to adapt to low flow velocities. The color gain is adjusted so that the first color artifacts appear.
In color mode, only separated islands of color-coded flow are visible
Due to the physiologically low flow velocities in healthy people, venous structures might not be visible over the whole length of the vascular segment. However, in cerebral veins no localized pathology (i.e., stenosis) occurs and the vessel does not possess valves or muscle layers to actively regulate venous diameter so that even such a measurement is fairly representative for the vessel segment.
I can’t properly delineate the Doppler frequency spectrum
In order to display the venous Doppler frequency spectrum correctly, it is important to use either a low or no wall filter. A small sample volume helps to separate the venous flow signal from adjacent arterial flow.
Steps of investigation
Although there exists no formal consensus on the sequence of the intracranial venous examination, most groups use a fairly similar approach described below [4,5]. In principle, intracranial venous insonation is also possible using conventional transcranial Doppler sonography, but transcranial color-coded duplex sonography is usually preferred due to its imaging capabilities displaying vascular anatomy in relation to the brain parenchyma in real time.
Examination starts through the temporal acoustic bone window in the mesencephalic plane with the butterfly-shaped mesencephalon as a landmark.
The deep middle cerebral vein is constantly found adjacent the middle cerebral artery (Figure 22.2) with flow directed to the center of the brain.
From this position the transducer is angulated downwards so that the echogenic lesser wing and the pyramid of the sphenoid bone become visible. The sphenoparietal sinus is found in the rim of the echogenic lesser wing of the sphenoid, the superior petrosal sinus in the rim of the pyramid (Figure 22.3). Normal flow direction of both sinuses is directed away from the probe toward the cavernous sinus which itself is not visible.
Starting again from the mesencephalic plane, the transducer is angulated upwards following the course of the posterior cerebral artery. The basal vein is found slightly cranial from the P2-segment of the posterior cerebral artery. Both display a flow away from the probe (Figure 22.4).
As a next step, the brightness mode (B-mode) depth is increased so that the contralateral skull becomes visible.
The great cerebral vein (of Galen) is found immediately behind the echogenic pineal gland behind the double reflex of the third ventricle as B-mode landmarks. Flow direction is away from the transducer (Figure 22.4).
In order to examine the straight sinus, the anterior tip of the transducer needs to be rotated upwards to align the insonation plane with the plane of the apex of the cerebellar tentorium which possesses an increased echogenicity (Figure 22.5). The course of the straight sinus is directed away from the transducer toward the confluens sinuum.
From this position the transducer is angulated downwards again to depict the contralateral transverse sinus (Figure 22.6). Using a more cranial probe position and an upwards tilt the ipsilateral transverse sinus can be insonated [6]. This approach seems to increase the detection rate.
During transforaminal examination, venous flow signals directed toward the transducer can be picked up. These signals originate from the vertebral venous plexus and the inferior petrosal sinus which runs in the vicinity of the basilar artery.
Frontal and occipital acoustic bone windows have been described which can be used to examine the midline venous vessels (internal cerebral veins, great cerebral vein and straight sinus) [7,8]. These windows are used by specialists mainly for scientific reasons. They are hampered by a high rate of insufficient acoustic penetration.
Deep middle cerebral vein (dMCV) adjacent to the middle cerebral artery (MCA) and an example of the venous Doppler frequency spectrum.
Sphenoparietal sinus in the echogenic lesser wing of the sphenoid and the superior petrosal sinus in the rim of the pyramid.
Basal vein (BV) draining into the great cerebral vein (of Galen) (GCV). The echogenic pineal gland is marked in the figure. The Doppler trace is an example of a registration from the BV.
Ultrasound insonation of the straight sinus (SR).
Insonation of the transverse sinus.
Reproducibility and normal values
Reproducibility of venous measurements has been examined in only one study [9], which found it to lie in the range of what is known from the intracranial arterial system. Angle correction seems not to be of great value in the venous system. Detection rates are generally higher for cerebral veins than for the sinuses. The latter are situated in an unfavorable anatomical position for insonation. Normal values and detection rates in healthy controls are summarized in Tables 22.1 and 22.2 [2]. Intracranial venous Doppler signals display a low pulsatility with yet a constant outwards flow. The reason is that intracranial veins are enclosed in the cranial cavity with an intrinsic pressure with outflow governed by a Starling resistor.
| Flow velocity (cm/s) | Detection rate | |
|---|---|---|
| Deep middle cerebral vein | 4–15/3–11 | 53–95% |
| Basal vein | 7–20/5–15 | 85–100% |
| Great cerebral vein (of Galen) | 6–32/4–25 | 84–94% |
| Sphenoparietal sinus | 27 ± 17 | 84% |
| Superior petrosal sinus | 27 ± 17 | 84% |
| Straight sinus | 6–39/4–27 | 23–82% |
| Transverse sinus | 6–56/5–38 | 20–84% |
| Reference | Methods | Results | Notes |
|---|---|---|---|
Methodology, normal values, reproducibility | |||
| Valdueza et al. [28] | TCD of the deep cerebral veins in 60 healthy volunteers | High detection rate of the basal vein only 27% for the deep middle cerebral vein. Normal FV decrease with age | Among the first systematic ultrasound studies of the cranial venous system in healthy adults |
| Valdueza et al. [29] | TCD of the parasellar region in 43 healthy adults | Definition of normal FV values of the sphenoparietal sinus and superior petrosal sinus | The only study providing normal values for the cavernous sinus inflow region |
| Doepp et al. [30] | TCD of the inferior petrosal sinus in 80 persons without cranial venous disease | Definition of normal FV values of the inferior petrosal sinus | The only study providing normal values for this region |
| Baumgartner et al. [31] | TCCS of the deep cerebral veins and posterior fossa sinuses in 120 healthy adults | Definition of normal values | Higher detection rates with TCCS than with TCD |
| Stolz et al. [32] | TCCS of the deep cerebral veins and posterior fossa sinuses in 130 healthy adults | Definition of normal values | Higher detection rates with TCCS than with TCD |
| Baumgartner et al. [7] | Definition of the occipital acoustic window for TCCS and normal values in 120 healthy adults | Definition of a new acoustic window for TCCS in adults and of normal values | |
| Stolz et al. [8] | Definition of frontal acoustic windows for TCCS and normal values in 75 healthy adults | Definition of new acoustic windows for TCCS in adults and of normal values | |
| Stolz et al. [9] | Study on the inter- and intraobserver reliability of venous TCCS in 23 healthy adults | For cerebral veins the 2SD variation is up to 3.2 cm/s and for sinuses up to 7.7 cm/s. Angel correction results in higher variations. For comparison, variability in the arterial system was assessed | The measurement variability for venous TCCS is in the relative range that can be expected for intracranial arteries |
Cerebral venous and sinus thrombosis | |||
| Stolz et al. [33] | TCCS evaluation of 8 CVST patients with follow-up | Definition of indirect diagnostic criteria: increased venous flow velocities | Clinical recovery coincided with decreases in blood flow velocity |
| Ries et al. [11] | Contrast-enhanced TCCS in 14 patients suspected to have TS thrombosis | Unenhanced TCCS displayed flow in 7/28 TS. Occlusion or aplasia were identified in 3 of 4 patients using contrast-enhanced TCCS. TCCS was pathological in 88% of patients | Contrast-enhanced venous TCCS has limited sensitivity and specificity |
| Valdueza et al. [15] | Prospective study of 18 patients using TCD including follow-up | Highest venous FVs ranged from 20 to 150 cm/s. In more than 80% of patients. FV decreased during follow-up | No predictive value was seen regarding the outcome in ratio to the absolute FVs nor their decrease |
| Stolz et al. [12] | Prospective series of 26 patients examined with TCCS including follow-up | Pathological ultrasound in 69% of patients. No difference in NIHSS in the acute phase of patients with normal or pathological venous TCCS on admission. Initially normal venous TCCS or normalized TCCS within 90 days was significantly related to favourable outcome | This fairly large study suggests a prognostic value |
| Canhão et al. [34] | Series of 6 patients examined with TCD | Pathological ultrasound in 50% of cases | |
| Schoser et al. [19] | Serial venous TCD of the basal vein and the straight sinus in 25 patients with raised intracranial pressure | Tight correlation between ICP and FV in the basal vein (r = 0.645; P <0.002) and straight sinus (r = 0.928; P <0.0003) | Could not be reproduced by others |
| Mursch et al. [16] | Prospective monitoring of the FVs in the BV in 66 patients after subarachnoid hemorrhage. In 14 patients correlation of venous FVs with CBF | In patients with permanent neurological deficits venous FVs were significantly reduced. The correlation between changes in venous FVs to changes in CBF (r =0.78, P <0.001) was closer than between changes arterial FVs to the changes in CBF (r =0.54, P <0.05) | Patients with higher venous FVs seem to have a better clinical outcome than patients with lower venous FVs. Changes in CBF correlate better with venous than with arterial FVs |
| Mursch et al. [17] | Prospective monitoring of the FVs in the BV in 82 patients after head trauma. Assessment of outcome after 6 months on the Glasgow Outcome Score (GOS) | During the study period, venous FVs on the side of trauma were higher in the patients with favourable outcomes (GOS = 4 and 5) compared to patients with unfavourable outcomes (GOS = 2 and 3). This was not observed for the arterial FVs | Serial measurement of venous flow velocities is a prognostic marker |
CBF, cerebral blood flow; FV, flow velocity; ICP, intracranial pressure; TCCS, transcranial color-coded duplex sonography; TCD, transcranial Doppler sonography.
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