Brain tumor imaging with transcranial sonography: state of the art and review of the literature.

Transcranial sonography (TCS) is a widely used non-invasive bedside method to evaluate the brain, its vessels, perfusion and pathologies. Transcranial brain tumor sonography emerged in the early nineties and while B-mode imaging and Color-Doppler have acquired widespread use, especially for intraoperative imaging, other ultrasound modalities such as Perfusion Imaging are applied more in the research field. The aim of this review is to give an overview of the different ultrasound modalities and their respective application in sonographic brain tumor imaging.

Comparison of perfusion harmonic imaging and perfusion mr imaging for the assessment of microvascular characteristics in brain tumors.

PURPOSE: The purpose of this study was to evaluate the potential of perfusion harmonic imaging (pHI) for assessing microvascular characteristics of brain tumors and to compare this ultrasound technique to perfusion MRI (pMRI). MATERIALS AND METHODS: Twenty-five patients with brain tumors underwent transtemporal pHI and fourteen of these patients underwent additional pMRI. Time-intensity curves of two different regions of interest (ROIs; (1) enhancing tumor; (2) healthy brain) were calculated off-line, and the following parameters were compared between the two ROIs and the two methodologies: time-to-peak intensity (TTP [sec]), the ratios of the peak intensities (PI ratio), the ratios of the positive slope gradient (PG ratio) and the ratios of the area under the curve (AUC ratio). p < 0.05 was considered statistically significant. RESULTS: Four of 25 patients were excluded due to bone window insufficiency or unfavorable tumor location. Focal abnormal echogenicity was detected in native B-mode in 86 % of the patients. Contrast agent administration led to remarkable echo enhancement in the tumor in all patients with corresponding time-intensity curves. Both pHI and pMRI showed significant differences with respect to the mean PI, PG and AUC (pHI: p < 0.001 / < 0.001 / < 0.001; pMRI: p < 0.05 / < 0.05 / < 0.001) when comparing tumor to healthy brain. The TTP was not significantly different in tumor and brain tissue. Comparison of pHI and pMRI data did not show any significant differences for three of four parameter ratios between both methodologies. CONCLUSION: PHI provides a new technique for assessing microvascular characteristics of brain tumors reflecting their abnormal perfusion. Overall comparison of this methodology to pMRI demonstrated encouraging results. Further studies should address the clinical potential of pHI especially in view of microvascular response to anti-angiogenic treatment.

Transcranial ultrasound perfusion imaging: implementation of a low MI and a high frame rate.

PURPOSE: Conventional transcranial ultrasound perfusion imaging (UPI) depends on bolus injection and is limited to triggered imaging. To improve our set-ups, we compared two imaging modalities with two different frame rates (FR) and mechanical indices (MI), intending to approach conditions more similar to real time imaging in order to increase parameter precision. MATERIALS AND METHODS: Fifteen healthy volunteers were investigated twice with UPI after i. v. administration of 1 ml of SonoVue(R): first, with a high MI (1.6) and a low FR (0.67 Hz)) and second, with a low MI (1.0) and a high FR (5 Hz). Apart from visual analysis, time-intensity curves were calculated from three regions of interest (ROI) and peak intensity (PI), time to PI (TP), and area-under-the-curve (AUC) were compared between the two imaging modalities. RESULTS: Visually, only scarce contrast enhancement was observed in 10/15 probands, and penetration depth was markedly lower at the low MI/high FR setting, while the high MI/low FR setting lead to very intense enhancement in 13/15 individuals. Signal-to-noise-ratio was higher at the low MI/high FR setting. TP was not significantly different between the two set-ups (p > 0.05). PI and AUC were significantly lower at the low MI/high FR setting (p

Recovery of the blood pressure - cerebral flow relation after carotid stenting in elderly patients.

BACKGROUND: As a sensitive and convenient means for the cerebral hemodynamic monitoring, dynamic cerebral autoregulation testing could be especially useful in medical conditions where less invasive diagnostics and therapies are preferred. This study analysed the effect of carotid stenting on dynamic autoregulation in elderly patients focussing on the relation between blood pressure and cerebral blood flow velocity. METHODS: We examined 20 patients age 69 +/- 8 years with coexisting cerebrovascular and medical risk factors before and at least six month after stenting of severe carotid stenoses. Data were compared to 24 age-matched healthy controls. Slow spontaneous oscillations were studied in continuous recordings of Transcranial Doppler and beat-to-beat blood pressure. Analysis was based on the "high-pass filter model", which predicts a positive phase relationship between these oscillations. FINDINGS: Whereas phase shift angles were diminished (20.4 +/- 14.1 degrees ) before stenting, after stenting these values were significantly increased to normal (48.1 +/- 16.6 degrees ), to the level of controls (46.7 +/- 15.9 degrees ). Medical conditions such as coronary artery disease, arterial hypertension, and dyslipidemia did not diminish this recovery. The level of increase was inversely correlated with the initial autoregulatory deficit (r = -0.68) which was largest with insufficient collateral blood supply and symptomatic carotid stenoses. CONCLUSIONS: The study showed that an impaired cerebral autoregulation may recover after stent-guided carotid angioplasty even in the elderly with co-existing medical conditions. In this respect to regain vasomotor capability, patients with cerebrovascular risk factors seemed to benefit particularly.

Intimal flap in a common carotid artery in a patient with Marfan's syndrome.

Dissection of the common carotid artery is a rare but important complication of Marfan's syndrome. The following case describes a patient with formation of an intimal flap of the common carotid artery who had suffered from an aortic dissection years before.

Stroke recurrence and its prevention in patients with patent foramen ovale.

BACKGROUND: It is unclear whether medical or invasive (surgical or catheter interventional) treatment is preferable to prevent recurrence of cerebral ischemia in patients with patent foramen ovale (PFO) as the suspected cause of stroke and what the role of concomitant risk factors is in stroke recurrence. METHODS: Over a period of ten years, 124 patients (mean age 51 +/- 15 years) with cryptogenic cerebral ischemia and PFO were included into the study and prospectively followed over a mean of 52 +/- 32 months. Of these, 83 were treated medically, 34 underwent transcatheter closure, and seven had surgical closure of the foramen. Of the medically treated patients, 11 stopped medication during follow-up. Recurrent ischemic events and risk factors for recurrence were analyzed. RESULTS: Annual stroke recurrence rates were generally low and comparable in catheter and medically treated patients, and in patients who had stopped medication (2.9%/2.1%2.2%/year). Patients suffering from recurrence after transcatheter closure (n = 2) both had residual shunts. No stroke recurrence was observed in the few surgically treated patients. An atrial septal aneurysm was not a predictor of recurrent or multiple strokes (p > 0.05, OR = 0.31, and OR = 0.74). Large shunts and a history of previous ischemic events were considerably more frequent in patients with recurrent strokes (p < 0.05, OR = 5.0, and OR = 4.4). Pulmonary embolism and case fatality rates were significantly higher in patients with stroke recurrence (p < 0.001, and p < 0.01). CONCLUSIONS: The absolute risk of recurrent cerebrovascular events in patients with PFO receiving medical or catheter interventional therapy is low. The small group of untreated patients had a comparably low rate of stroke recurrences. Previous ischemic events and shunt size were risk factors in this observational study. Given conflicting findings across multiple studies, enrollment into a randomized controlled trial would be the optimal choice.

Impact of vertebral artery disease on dynamic cerebral autoregulation.

OBJECTIVES: This study applied dynamic cerebral autoregulation (DCA) testing distally to severe bilateral vertebral artery disease (BVAD). METHODS: Using continuous monitoring of beat-to-beat blood pressure and transcranial Doppler of the posterior cerebral arteries (PCA) were examined in 20 patients with BVAD and 22 controls. DCA testing was based on the 'high-pass filter model', which predicts a positive phase relationship between spontaneous oscillations (M-waves 3-9 cpm and R-waves 9-20 cpm) in blood pressure and cerebral blood flow velocity. RESULTS: In patients with BVAD, DCA testing detected autoregulatory deficits of different degrees. The lowest M-wave phase shift angles were found in the PCA territory distally to intracranial BVAD. CONCLUSION: This study suggests that DCA testing of the PCA could help to quantify the hemodynamic impact of BVAD. It highlights the relevance of functional TCD sonography as a useful diagnostic tool for the hemodynamic evaluation of vertebrobasilar disease.

[Cerebral perfusion sonography in comparison with perfusion MRT: a study with healthy volunteers]. / Zerebrale Perfusionssonographie im Vergleich zur Perfusions-MRT: Eine Normalprobandenstudie.

AIM: Perfusion harmonic imaging (PHI) has been used for several years now in neurological as well as other patients. The aim of the study was to compare PHI with perfusion-weighted MR tomography (pMRT) for the evaluation of cerebral parenchymal perfusion. Furthermore, the influence of different trigger intervals on the contrast kinetics in PHI was analysed. METHOD: Fifteen healthy individuals were evaluated with two transtemporal PHI investigations and one pMRT. In PHI, 62 time-triggered images at two different trigger intervals (1 and 0.4 Hz) were recorded after an intravenous bolus of 2 ml of SonoVue(R). pMRT was carried out according to a standard technique using 0.2 mmol/kg Gadolinium-DTPA (Magnevist) and T2*-weighted EPI-sequences. Time-intensity curves of PHI and pMRT-determined data including peak intensity (PI), time-to-peak-intensity (TTP [s]), and area-under-the-curve (AUC) were calculated off-line from 4 regions of interest: ipsi- and contralateral thalamus (i-TH, k-TH), lentiform nucleus (NUC), and white matter (ML). These parameters were compared between the data sets of the two different trigger intervals. Additionally, ratios of the above parameters were calculated to compare the two methods (TH/NUC and TH/ML). RESULTS: Comparison of the two trigger intervals showed significantly lower AUC-values at the higher trigger interval, while the trigger interval had no significant impact on PI- and TTP- values. A good correlation was seen between the trigger intervals for AUC-values and, to a lesser extent, for PI-values. TTP-values did not correlate. TTP was the only depth-independent parameter. There was no significant difference between PHI and pMRT in 10 of 12 parameter ratios analysed. Merely the PI-ratio of i-TH/ML was significantly different at both trigger intervals. CONCLUSION: Regarding the development of adequate set-ups for transcranial PHI, further parameters with impact on contrast agent kinetics (MI, dose of contrast agent) have to be taken into account in addition to the trigger interval. Our findings suggest that, within certain limits, PHI is an imaging technique representing a valuable alternative to MR perfusion imaging, with the TTP representing the most reliable parameter. The AUC is useful for semi-quantitative evaluation of brain perfusion.

M-wave analysis and passive tilt in patients with different degrees of carotid artery disease.

BACKGROUND AND PURPOSE: Carotid artery disease (CAD) is able to critically impair cerebral autoregulation which increases the risk for stroke. As therapeutic strategy largely depends on the degree of CAD, we investigated whether this gradation is also related to significant changes in autoregulatory capacity. We applied cross-spectral analysis (CSA) of spontaneous Mayer-wave (M-wave) oscillations and passive tilting (PT) to test cerebral autoregulation. METHODS: Cerebral autoregulation was tested in 102 patients with carotid stenosis (> or =70%) or occlusion and 14 controls by comparison of continuous transcranial Doppler sonography of the middle cerebral artery and beat-to-beat arterial blood pressure (ABP) during PT to 80 degrees head-up position as well as by CSA of M-waves (3-9 cpm). RESULTS: The orthostatic decrease of cerebral blood flow velocity (CBFV) was not correlated with the degree of CAD and showed a lower sensitivity and specificity than phase angle shifts between M-waves in ABP and CBFV (sensitivity: 75-80%, specificity: 86%). Phase angles were gradually lowered in carotid stenoses > 70%, but apparently, they were only moderately correlated with the degree of CAD (r = -0.35, P < 0.01). An additional influencing factor seemed to be the sufficiency of collateralization. CONCLUSIONS: The results show that CSA of M-waves is more appropriate for testing autoregulation than PT. CSA suggests that the capacity to autoregulate depends to a certain extent on the degree of CAD but is also influenced by the sufficiency of collateral pathways and pre-existing strokes.

Dynamic autoregulation testing in the posterior cerebral artery.

BACKGROUND AND PURPOSE: Dynamic autoregulation has been studied predominantly in the middle cerebral artery (MCA). Because certain clinical conditions, ie, presyncopal symptoms or hypertensive encephalopathy, suggest a higher vulnerability of autoregulation within posterior parts of the brain, we investigated whether the cerebral blood flow velocity (CBFV) is modulated differently within the posterior cerebral artery (PCA). METHODS: Spontaneous oscillations of CBFV and arterial blood pressure (ABP) in the frequency range of 0.5 to 20 cycles per minute were studied in 30 volunteers (supine and tilted positions). Analysis was based on the "high-pass filter model," which predicts a specific frequency-dependent phase and amplitude relationship between oscillations in CBFV to ABP. These parameters, characterized as phase shift angles and transfer function gains, were calculated from simultaneously recorded beat-to-beat blood pressure and transcranial Doppler signals of the PCA and MCA by means of cross-spectrum analysis. RESULTS: In the MCA and PCA, phase shift angles were decreased, and gains were elevated with increasing oscillation frequency. The PCA gain values in supine and tilted positions were significantly higher than in the MCA. CONCLUSIONS: The phase and amplitude relationship between CBFV and ABP showed a frequency dependence in the PCA similar to that in the MCA. The study therefore suggests that the high-pass filter model of dynamic cerebral autoregulation can be applied to the PCA. In this model the generally higher gain values in the PCA indicate a lower damping of ABP oscillations, which are transmitted to the posterior part of cerebral circulation.

Dynamic autoregulation testing in patients with middle cerebral artery stenosis.

BACKGROUND AND PURPOSE: Cross-spectral analysis (CSA) of spontaneous oscillations in cerebral blood flow velocity (CBFV) and arterial blood pressure is considered a sensitive and convenient method for dynamic autoregulation testing. So far, it has been unclear whether CSA can be used to assess stenoses of the intracranial arteries. METHODS: This study for the first time applies CSA to 26 patients with low-, moderate-, and high-degree M1 stenoses and 14 normal control subjects. Using CSA, we studied spontaneous oscillations (M waves, 3 to 9 cpm; B waves, 0.5 to 3 cpm) in continuous recordings of transcranial Doppler of the middle cerebral artery and simultaneously recorded beat-to-beat blood pressure. RESULTS: A gradual decrease in pulsatility indexes confirmed the increasing hemodynamic relevance of the stenoses. Compared with control subjects, M-wave phase shifts between CBFV and blood pressure were gradually reduced with increasing degree of M1 stenosis (control subjects, 44.6+/-21.1 degrees; high-degree stenosis, 16.7+/-19.5 degrees ). The phase relation between B waves in blood pressure and CBFV was shifted to positive values (low-degree stenosis, -9.7+/-108.4 degrees; high-degree stenosis, 50.9+/-43.8 degrees ). CONCLUSIONS: Because B- and M-wave phase shifts seem to characterize the degree of autonomy of CBFV modulation, this study suggests that with increasing degree of M1 stenosis, the arteriolar function is impaired. It shows that CSA is of indicative use for the assessment of intracranial artery stenosis.

Vocal cord palsy resulting from spontaneous carotid dissection.

OBJECTIVES/HYPOTHESIS: Vocal cord palsy has a variety of causes, such as malignant tumors of the thyroid, lung, or upper mediastinum, aortic aneurysm, surgery of the thyroid, and infectious diseases. STUDY DESIGN: Case report. METHODS: A 43-year-old biologist had a holocephalic headache and right-sided neck pain for 1 day. Five days later, he developed paralysis of the right-side vocal cord. In addition, an angiotensin converting enzyme (ACE) inhibitor was administered because the patient had high systolic and diastolic blood pressures, which were formerly not known to the patient. Five days after admission, a temporary sensorimotor hemiparesis occurred. RESULTS: Neurological examination revealed, in addition to the known paralysis of the right-side vocal cord, right-side palatoplegia, right-side hypoglossal nerve palsy, and mild dysphagia. Duplex sonography showed evidence of lumen narrowing of the right-side internal carotid artery caused by an hypoechogenic mural hematoma. Magnetic resonance imaging (0.5 T, Philips Gyroscan) revealed a circumscribed dissection of the right-side internal carotid artery from the carotid bifurcation to the petrosal segment. The diffusion-weighted magnetic resonance imaging scan of the brain also demonstrated multiple embolic ischemic lesions in the right hemisphere. CONCLUSION: Internal carotid artery dissection must be included in the differential diagnosis of lower cranial nerve palsy and should be assessed by duplex ultrasonography and magnetic resonance imaging.

Second harmonic imaging: a new ultrasound technique to assess human brain tumour perfusion.

BACKGROUND: Second harmonic imaging is a new ultrasound technique that allows evaluation of brain tissue perfusion after application of an ultrasound contrast agent. OBJECTIVE: To evaluate the potential of this technique for the assessment of abnormal echo contrast characteristics of different brain tumours. METHODS: 27 patients with brain tumours were studied. These were divided into four groups: gliomas, WHO grade III-IV (n = 6); meningiomas (n = 9); metastases (n = 5); and others (n = 7). Patients were examined by second harmonic imaging in a transverse axial insonation plane using the transtemporal approach. Following intravenous administration of 4 g (400 mg/ml) of a galactose based echo contrast agent, 62 time triggered images (one image per 2.5 seconds) were recorded and analysed off-line. Time-intensity curves of two regions of interest (tumour tissue and healthy brain tissue), including peak intensity (PI) (dB), time to peak intensity (TP) (s), and positive gradient (PG) (dB/s), as well as ratios of the peak intensities of the two regions of interest, were derived from the data and compared intraindividually and interindividually. RESULTS: After administration of the contrast agent a marked enhancement of echo contrast was visible in the tumour tissue in all patients. Mean PI and PG were significantly higher in tumour tissue than in healthy brain parenchyma (11.8 v 5.1 dB and 0.69 v 0.16 dB/s; p < 0.001). TP did not differ significantly (37.1 v 50.2 s; p = 0.14). A tendency towards higher PI and PG as well as shorter TP was apparent in malignant gliomas. When comparing different tumour types, however, none of these variables reached significance, nor were there significant differences between malignant and benign tumours in general. CONCLUSIONS: Second harmonic imaging not only allows identification of brain tumours, but may also help in distinguishing between different tumour types. It gives additional and alternative information about tumour perfusion. Further studies are needed to evaluate the clinical potential of this technique in investigating brain tumours-for example in follow up investigations of patients undergoing radiation or chemotherapy-especially in comparison with neuroradiological and neuropathological findings.

[Isolated cranial nerve palsy secondary to carotid dissection]. / Isolierte Hirnnervenausfälle bei Karotisdissektionen.

Cranial nerve palsy has a variety of causes such as cerebral ischemia, nerve ischemia in diabetes, infectious and noninfectious meningitis, subarachnoid hemorrhage, malignant tumors of the skull base, neck, or upper mediastinum, aortic aneurysm, surgery of the thyroid,and many more. We report two cases of spontaneous carotid dissections leading to cranial nerve palsies, which is an uncommon cause of isolated cranial nerve palsies.ICA dissection must therefore be included in the differential diagnosis of lower cranial nerve palsy and should be assessed by duplex ultrasound and MRI as is demonstrated in our cases.

Detection of stenoses in the anterior circulation using frequency-based transcranial color-coded sonography.

Atherosclerotic stenoses of the intracranial vessels are less frequent than those of the extracranial vessels, but they are associated with a considerable annual stroke rate. The aim of the present study was to investigate the usefulness of frequency-based transcranial color-coded sonography (TCCS), transcranial Doppler sonography (TCD) and digital subtraction angiography (DSA) in patients with middle cerebral artery (MCA) and intracranial internal carotid artery (ICA) stenosis. Forty patients presenting with 48 intracranial stenoses of the anterior circulation were involved in the study. The stenoses were detected in the neurovascular laboratory during routine TCD examinations. All patients underwent an additional frequency-based TCCS examination. Both the axial and coronal planes were obtained to allow the exact localization of MCA stenosis and differentiation from intracranial ICA stenosis. Angle-corrected flow velocity measurements were performed if straight vessel compartments were 20 mm or more in length. A total of 18 stenoses (44%) were investigated additionally with DSA. According to the investigation with TCD, 20 (42%) stenoses were low-grade, 12 (25%) were moderate, and the remaining 16 (33%) were severe. Angle-corrected flow velocity measurements obtained with the integrated pulse-wave Doppler device of the TCCS machine were highly correlated (0.912, p < 0.001) with those obtained with TCD. TCCS achieved a reliable differentiation of MCA main stem stenosis vs. intracranial ICA stenosis in 7 patients and vs. MCA branch stenosis in 4 patients, but TCD failed in these two subgroups. The agreement between DSA and TCCS to evaluate semiquantitatively 18 intracranial stenoses resulted in a weighted-kappa value of 0.764. The major clinically relevant advantages of TCCS over TCD in MCA stenosis are its ability to differentiate MCA trunk stenosis from terminal ICA or MCA branch stenosis reliably and to perform angle-corrected flow velocity measurements.

Three-dimensional transcranial color-coded sonography of cerebral aneurysms.

BACKGROUND AND PURPOSE: The role of 2-dimensional transcranial color-coded sonography (2D-TCCS) as a diagnostic tool in cases of vascular alteration is unquestioned. The skill of the operator, however, may be responsible for some intertrial variability. The clinical value of a new, workstation-based, 3D reconstruction system for TCCS was evaluated in patients with intracranial aneurysms. METHODS: Thirty patients with 30 intracranial aneurysms were investigated (8 men, 22 women; mean+/-SD age 54+/-17 years). The TCCS examinations were performed with a 2-MHz probe using the power mode. The 3D system (3D-Echotech, Germany) consisted of an electromagnet, which induced a low-intensity magnetic field near the head of the patient. A magnetic position sensor was attached to the ultrasound probe and transmitted the spatial orientation of the probe to a workstation, which also received the corresponding 2D-images from the video-port of the duplex machine. The echo contrast enhancer D-galactose (Levovist, Schering, Germany) was used in all patients to improve the signal-to-noise ratio. All patients underwent presurgical digital subtraction angiography (DSA) to demonstrate the aneurysm. RESULTS: Twenty-nine of 30 angiographically proven intracranial aneurysms (97%) were detected by 3D-TCCS. The aneurysmal diameter estimated by DSA ranged from 3 to 16 mm (mean 7. 2+/-3.6 mm). A comparison of the 3 main diameters of each aneurysm revealed a correlation coefficient of 0.95 between DSA and 3D-TCCS. The 3D determination of the aneurysmal size by 2 experienced sonographers correlated with 0.96. CONCLUSIONS: 3D-TCCS is a new, noninvasive method to investigate intracranial aneurysms. The differentiation between artifacts and true changes of the vessel anatomy is much easier in 3D-TCCS than in conventional 2D-TCCS. The new method yields an excellent correlation with the gold standard, DSA. Because the same 3D-TCCS data can be postprocessed by different investigators, it may be possible to improve reproducibility and increase the objectivity of transcranial color-coded duplex sonography.

Transthoracic echocardiography using second harmonic imaging: diagnostic alternative to transesophageal echocardiography for the detection of atrial right to left shunt in patients with cerebral embolic events.

OBJECTIVES: We sought to evaluate whether transthoracic contrast echocardiography using second harmonic imaging (SHI) is a diagnostic alternative to transesophageal contrast echocardiography (TEE) for the detection of atrial right to left shunt. BACKGROUND: Paradoxic embolism is considered to be the major cause of cerebral ischemic events in young patients. Contrast echocardiography using TEE has proven to be superior to transthoracic echocardiography (TTE) for the detection of atrial shunting, SHI is a new imaging modality that enhances the visualization of echocardiographic contrast agents. METHODS: We evaluated 111 patients with an ischemic cerebral embolic event for the presence of atrial right to left shunt using an intravenous (IV) contrast agent in combination with three different echocardiographic imaging modalities: 1) TTE using fundamental imaging (FI); 2) TTE using SHI; and 3) TEE. The severity of atrial shunting and the duration of contrast visibility within the left heart chambers were evaluated for each imaging modality. Image quality was assessed separately for each modality by semiquantitative scoring (0 = poor to 3 = excellent). Presence of atrial right to left shunt was defined as detection of contrast bubbles in the left atrium within the first three cardiac cycles after contrast appearance in the right atrium either spontaneously or after the Valsalva maneuver. RESULTS: A total of 57 patients showed evidence of atrial right to left shunt with either imaging modality. Fifty-one studies were positive with TEE, 52 studies were positive with SHI, and 32 were positive with FI (p<0.001 for FI vs. SHI and TEE). The severity of contrast passage was significantly larger using SHI (61.6+/-80.2 bubbles) compared to FI (53.7+/-69.6 bubbles; p<0.005 vs. SHI) but was not different compared to TEE (43.9+/-54.3 bubbles; p = NS vs. SHI). The duration of contrast visibility was significantly longer for SHI (17.4+/-12.4 s) compared to FI (13.1+/-9.7 s; p<0.001) and TEE (11.9+/-9.6 s; p<0.02). Mean image quality improved significantly from FI (1.5+/-0.8) to SHI (2.0+/-0.8; p<0.001 vs. FI) and TEE (2.5+/-0.7; p<0.001 vs. SHI). CONCLUSIONS: In combination with IV contrast injections, TEE and SHI have a comparable yield for the detection of atrial right to left shunt. Both modalities may miss patients with atrial shunting. In young patients with an unexplained cerebrovascular event and no clinical evidence of cardiac disease, a positive SHI study may obviate the need to perform a TEE study to search for cardiac sources of emboli.

[Clinical application of transcranial color-coded duplex ultrasound for detection of intracranial aneurysms]. / Klinische Anwendung der TCCD zum Nachweis intrakranieller Aneurysmen.

We investigated 88 Patients with a total of 102 angiographically diagnosed intracranial aneurysms by means of transcranial colour coded Duplex sonography (TCCD) during a time period of 15 months. Both the size and the localization of the aneurysms were determined. Seventy aneurysms (77%) with a diameter of 16 +/- 8 mm (6-55 mm) were detectable, with excellent visualization in 36 (42%), moderate visualization in 34 (40%), and no sufficient visualization in 16 (16%) aneurysms, respectively. In another 16 cases (16%) there was no sufficient vone window. Thrombotic material inside the aneurysm was detectable in 16/20 cases (75%), visualization of coil embolized aneurysms in 12/25 patients (48%). TCCD allows the follow up of cerebral aneurysms, with the detection of thrombosis and treatment effects after embolization. The method is not valid for the detection of intracranial aneurysms.