Power Doppler compared to color-coded duplex sonography in the assessment of the basal cerebral circulation

Reproducibility of the fetal cerebral vessels assessment in full and late term pregnancies

Objective: Data concerning feasibility of the fetal cerebral Doppler examination in full term and late term pregnancy is lacking. Our purpose was to perform an evaluation of these arteries with power Doppler ultrasound, calculating the percentage of identification and measurement and the intraobserver reproducibility.Methods: This was a cross sectional study evaluating a population of 578 normally grown fetuses divided according to the week of examination. The first group included fetuses examined at week 40 (N = 323) and the second fetuses examined at week 41 (N = 255). The three major branches of the internal carotid artery (anterior, middle and posterior cerebral arteries, ACA, middle cerebral artery (MCA), posterior cerebral arteries (PCA)) and their anastomosis (A1, A2, P1, P2) were examined with power Doppler ultrasonography by three independent ultrasonographers. The proportion of vessel identified and measured was calculated and the reproducibility among the three operators was investigated.Results: The major arteries at the circle of Willis were fully identified/measured in 65/56 and 62/48% of fetuses at 40 and 41 weeks. The MCA obtained the higher percentage of identification and measurement at both periods (> 80 and >70%). The entire set of anastomosis were less frequently identified/measured at both periods (50/< 50% of cases), especially in the A2 segment. The best agreement was obtained in the MCA and the worst in the PCA-P1 segment.Conclusions: At 40 and 41 weeks, the fetal cerebral vessels, especially the MCA, are suitable for power Doppler evaluation, providing an interesting tool to evaluate fetal hemodynamics in full and late term pregnancy.

The Posterior Cerebral Artery and its Main Cortical Branches Identified with Noninvasive Transcranial Color-Coded Duplex Sonography

PURPOSE

To differentiate PCA segments and cortical branches by means of transcranial color-coded duplex sonography (TCCD) and to measure flow parameters at rest and during visual stimulation.

MATERIALS AND METHODS

60 healthy subjects with a good acoustic temporal bone window were examined. The main stem of the PCA (P1, P2 and P3) and 4 main cortical branches - the anterior temporal artery (ATA), the occipital temporal artery (OTA), the parietooccipital artery (POA) and the calcarine artery (CA) - were assessed using an axial transtemporal approach. Systolic and diastolic blood flow velocities (BFVs) were recorded at rest and during visual stimulation.

RESULTS

Identification of the P1 segment of the PCA was successful in 97.5% (117/120) of cases. The P2 and P3 segments were visualized in all cases. The 4 main cortical branches could be identified to varying degrees: ATA in 88%, OTA in 96%, POA in 69% and CA in 62%. There was an evoked flow response in the P2 main stem and in all cortical branches. The most pronounced increase in diastolic/systolic BFV after visual stimulation test was seen in the CA (42%/35%), followed by P2 (30%/24%), the POA (27%/27%), the OTA (16%/13%) and the ATA (9%/8%).

CONCLUSION

Insonation through the temporal bone window with TCCD confidently allows the assessment of the P1 to P3 segments of the PCA as well as the 2 proximal branches, the ATA and the OTA. An ultrasound-based classification of PCA anatomy and its cortical branches may be used as a noninvasive method for the evaluation of posterior circulation pathology.

Intracranial collateral pathways assessed by contrast-enhanced three-dimensional transcranial color-coded sonography

Individual parameter settings of the duplex machine and limited insonation angles may influence the visualization of small intracranial vessels in 2-D transcranial color-coded sonography. The aim of our study was the morphologic assessment of intracranial collateral pathways (first auditory area celiac artery, A(1)CA; anterior communicating artery, AComA; first parental generation celiac artery P(1)CA; posterior communicating artery, PComA) using 3-D transcranial color-coded duplex sonography (3-D TCCS) and digital subtraction angiography (DSA). A total of 41 patients with large vessel disease and 30 patients who had suffered subarachnoidal hemorrhage (mean age 52 +/- 15 years) were involved. In all patients, angiography was performed within 10 days following 3-D sonography. The patients were investigated with a color-coded duplex system using the power mode. Contrast enhancement was achieved by continuous infusion of a galactose-based echo-enhancer using a perfusor pump. The 3-D system consists of an electromagnet that induces a low-intensity magnetic field near the head of the patient. A magnetic position sensor is attached to the ultrasound (US) probe and transmits the spatial orientation to a personal computer, which also receives the corresponding 2-D images from the video port of the duplex machine. Angiography revealed a "complete" circle of Willis in one third of the patients and, in the remaining patients at least one vessel was hypoplastic or absent. Sufficient temporal bone windows allowed the sonographic investigation of 466 (94%) of 497 expected arterial segments. The comparison of both techniques resulted in a weighted kappa value of 0.56 for the A(1)CA and 0.63 for the AComA. In the posterior circulation kappa values of 0.56 for the P(1)CA and 0.43 for the PComA were calculated. In 50 vessels (10%), 3-D sonography misdiagnosed the diameter of a collateral vessel as normal and angiography revealed hypoplasia or aplasia of this vessel. The main advantage of 3-D TCCS is that it enables the investigator to reconstruct virtually any arbitrary view angle. Compared with angiography or magnetic resonance (MR) angiography, 3-D sonography can be performed easily in critically ill patients on stroke units or intensive care units. The noninvasive assessment of the circle of Willis may be useful in patients who undergo carotid surgery without angiography. Combined with hemodynamic information, contrast-enhanced 3-D TCCS might increase the diagnostic impact of transcranial US.

Basal ganglia alterations and brain atrophy in Huntington's disease depicted by transcranial real time sonography

OBJECTIVES AND METHODS

Transcranial real time sonography (TCS) was applied to 49 patients with Huntington's disease and 39 control subjects to visualise alterations in the echotexture of the basal ganglia. For comparison T1 weighted, T2 weighted, and fast spin echo MRI was performed in 12 patients with Huntington's disease with and in nine patients without alterations of the basal ganglia echotexture as detected by TCS and T1 weighted, T2 weighted, and fast spin echo MRI. Furthermore, the widths of the frontal horns, third ventricle, and the lateral ventricles were depicted in TCS examinations and correlations examined with corresponding CT slices.

RESULTS

Eighteen out of 45 (40%) of the patients with Huntington's disease with adequate insonation conditions showed hyperechogenic lesions of at least one basal ganglia region. In 12 patients TCS depicted hyperechogenic lesions of the substantia nigra; in six patients the head of the caudate nucleus was affected. The lentiform nucleus (n=3) and the thalamus (n=0) were less often affected or spared. Hyperechogenic lesions were significantly more frequent in patients with Huntington's disease than in 39 control subjects, who had alterations of the echotexture in 12.8% (4/39) of the examinations. The number of CAG repeats and the clinical status correlated with the identification of hyperechogenic lesions of the substantia nigra (p<0.01). Hyperechogenic lesions of the caudate nucleus were associated with an increased signal intensity in T2 weighted MR images (p<0.05). All TCS parameters indicating brain atrophy correlated with CT findings (p<0.0001).

CONCLUSIONS

TCS detects primarily abnormalities of the caudate nucleus and substantia nigra in Huntington's disease. These changes in the echotexture may represent degenerative changes in the basal ganglia matrix and are partially associated with CAG repeat expansion and the severity of clinical findings.

Echo contrast-enhanced three-dimensional power Doppler of intracranial arteries

The purpose of this study was to evaluate the potential of contrast-enhanced three-dimensional (3-D) power Doppler (CE3DPD) in the assessment of intracranial vascular structures, and to compare the results with unenhanced 3-D power Doppler (3DPD) and magnetic resonance angiography (MRA) findings. We insonated 25 patients without cerebrovascular diseases through the temporal bone window using 3DPD and CE3DPD; for comparison, 13 patients underwent MRA. Identification rates of vascular segments and of small branches of intracranial vessels were evaluated by two independent investigators blinded to MRA results. In 21 patients with adequate insonation conditions, CE3DPD significantly improved identification rates compared to 3DPD for the complete visualization of the P1 segment (80.9 vs. 19.0%, p < 0.005, P2 segment (80.9 vs. 42.8%, p < 0.05 and A1 segment (85.7 vs. 38.1%, p < 0.005). Furthermore, CE3DPD depicted, in significantly more examinations, branches of the middle (MCA) and posterior cerebral artery (PCA). Interobserver agreement was higher than 95% for the main intracranial segments and branches of the MCA, but relatively low (80.1-85.7%) for branches of the PCA. In comparison to CE3DPD, MRA identified only parieto-occipital branches of the PCA, temporal branches of the MCA, frontal branches of the anterior cerebral artery and the MCA bifurcation more frequently and accurately. In 4 patients with inadequate acoustic temporal bone windows, the application of a galactose-based microbubble suspension allowed clear 3-D visualization of almost all major intracranial vascular segments and some branches of the large arteries. In conclusion, CE3DPD is a more sensitive ultrasonic tool compared to unenhanced 3-D reconstructions. It makes 3-D ultrasound imaging of the basal cerebral circulation easier to perform and interpret, by providing an improved spatially oriented display of image position. As such, this method may increase operator diagnostic confidence level under pathologic conditions.