Temporal Acoustic Window Research Articles

Evaluation of Cerebral Hemodynamics with Color-Coded Duplex Sonography: Normative Values with Correction of Insonation Angles

Background: Transcranial color-coded sonography (TCCS) allows direct observation of arteries and the possibility of correcting the insonation angle for reliable evaluation of hemodynamics. We obtained TCCS reference values of the cerebral hemodynamics after correction of insonation angles. Methods: We studied 195 healthy adults equally allocated into 3 age groups: 18-40, 41-60, and greater than or equal to 61 years. The middle (MCA), anterior (ACA), and posterior cerebral arteries (PCA) were evaluated through the temporal acoustic window using conventional pulsed transcranial Doppler and TCCS. Peak systolic, end diastolic, and mean blood flow velocities were registered, as well as pulsatility and resistance indices at 0° and with correction by alignment of insonation angle parallel to the blood flow vector. We derived normative values assuming both the parametric and nonparametric distributions. Results: We excluded 33 participants due to inadequate acoustic window (10.3%), carotid disease (2.1%), and embryonic variants (4.6%), leaving out 162 for final analysis (50% female, median age 48 years). The 2.5th-97.5th percentiles of the corrected angle for MCA was 0°-60°, ACA 0°-44°, and PCA 30°-60°. After angle correction, 2.5th-97.5th percentiles for flow velocity of MCA, ACA, and PCA were 37.7-112.5 cm/s, 25.6-71.2 cm/s, and 29.2-80.8 cm/s, respectively. There were wide discrepancies between hemodynamics values obtained with insonation angles at 0° and after angle correction. No differences were found between ultrasound methods at exactly 0° or between hemispheres, however, there were differences according to age and sex. Conclusions: Specific normative tables should be used in TCCS when the corrected angle is greater than 0° since the hemodynamics values greatly differ after correction of the insonation angle. Further studies are necessary to determine critical cutoffs indicating disease.

Substantia nigra hyperechogenicity in essential tremor and Parkinson's disease: a longitudinal study.

Essential tremor (ET) and Parkinson's disease (PD) sometimes overlap in their clinical expression with ET preceding PD onset, often leading to misdiagnosis. Transcranial sonography (TCS) has been shown to be a valid and non-invasive diagnostic tool to identify early idiopathic PD and to differentiate it from ET. The purpose of this study was to investigate the relevance of substantia nigra hyperechogenicity in patients with ET. A total of 138 patients (79 with PD, 59 with ET) and 50 matched controls underwent TCS examination at baseline. All patients were followed in a 3-year longitudinal assessment. A total of 10 subjects were excluded from the analysis due to the bilateral absence of a temporal acoustic window. During the follow-up period, 11 of the patients with ET developed new-onset parkinsonian features, without fulfilling criteria for PD diagnosis (ET+). Nine patients developed clinical features meeting diagnostic criteria for probable PD (ET-PD). Patients with ET- did not develop parkinsonian features. For each group, the maximum size of the substantia nigra hyperechogenicity was as follows: 5.62±5.40mm2 in the control group, 19.02±14.27mm2 in patients with PD, 9.15±11.26mm2 in patients with ET-, 20.05±13.78mm2 in patients with ET+ and 20.13±13.51mm2 in patients with ET-PD. ET-PD maximum values were significantly different from controls. Maximum values in patients with ET+ were different from both controls and patients with ET-. Substantia nigra hyperechogenicity in ET seems to represent a risk marker for developing early parkinsonian symptoms or signs in the 3years following TCS assessment.

Increased frequency of temporal acoustic window failure in rheumatoid arthritis: a manifestation of altered bone metabolism?

Assessment of intracranial vessels includes transcranial Doppler (TCD). TCD performance requires intact temporal acoustic windows (TAW). Failure of TAW (TAWF) is present in 8-20% of people. There have been no reports on TAWF in rheumatoid arthritis (RA). Altogether, 62 female RA patients were included. Among them, 20 were MTX-treated and biologic-free, 20 received infliximab, and 22 tocilizumab. The controls included 60 non-RA women. TAWF, temporal bone thickness, and texture were determined by ultrasound and CT. BMD and T-scores of multiple bones were determined by DEXA. Several bone biomarkers were assessed by ELISA. In RA, 54.8% of the patients had TAWF on at least one side. Neither TAW could be identified in 34% of RA subjects. In contrast, only 20.0% of control subjects had TAWF on either or both sides (p < 0.001). In RA vs controls, 53.0 vs 2.9% of subjects exerted the trilayer, "sandwich-like" structure of TAW (p < 0.001). Finally, in RA vs controls, the mean temporal bone thickness values of the right TAW were 3.58 ± 1.43 vs 2.92 ± 1.22mm (p = NS), while those of the left TAW were 4.16 ± 1.56 vs 2.90 ± 1.16mm (p = 0.001). There was close association between TAWF, bone thickness, and texture (p < 0.05). These TAW parameters all correlated with age; however, TAW failure and texture also correlated with serum osteoprotegerin. TAW bone thickness inversely correlated with hip BMD (p < 0.05). TAWF, thicker, and heterogeneous temporal bones were associated with RA. These features have been associated with bone loss and OPG production. Bone loss seen in RA may result in OPG release and stimulation of bone formation around TAW.

Thickness and texture of the squamous temporal bone in a Nigerian tertiary hospital

Background: Thickness and texture of the squamous temporal bones (STBs) are the two main patient factors that determine the outcome of transtemporal transcranial Doppler ultrasound. The aim of this study was to determine the thickness and texture of the STB as well as their association with biodemographic characteristics in a tertiary hospital in Southwest Nigeria. Material and Methods: Cranial computed tomography (CT) images of 142 adults acquired on a 64-slice multi-detector Toshiba Aquilion scanner were retrospectively evaluated for the thickness and texture of the bilateral STB at the expected location of the temporal acoustic window on a ClearCanvas® Workstation. Associations of thickness and texture of the STB with biodemographic data were determined by statistical analysis at P Results: There were 79 male (55.6%) participants and the overall mean age was 51 ± 17.3 years (49 ± 16.1 years in males and 53.4 ± 18.5 years in females). Mean thickness of the 284 STB was 3.21 ± 1.11 mm (range 1.2–8.7 mm), which was thicker on the left (3.3 ± 1.2 mm) than the right (3.1 ± 1.0 mm, P = 0.001). Thickness of STB showed significant increase (P Conclusion: Thickness of the squamous temporal bone varied significantly with age but not with gender, and the temporal squama were largely of a homogeneous texture. Overall, the important patient factors appear favorable for transtemporal cranial ultrasound in the majority of our participants.

Ultrasound Tissue Pulsatility Imaging Suggests Impairment in Global Brain Pulsatility and Small Vessels in Elderly Patients with Orthostatic Hypotension

Orthostatic hypotension (OH) is highly prevalent in the elderly, and this population can be exposed to serious complications, including falls and cognitive disorders, as well as overall mortality. However, the pathophysiology of OH is still poorly understood, and innovative methods of cerebral blood flow (CBF) assessment have been required to accurately investigate cerebrovascular reactivity in OH. We want to compare brain tissue pulsatility (BTP) changes during an orthostatic challenge in elderly patients over 80 with and without OH. Forty-two subjects aged 80 and over were recruited from the geriatric unit of the Hospital of Tours, France, and were divided into two groups according to the result of an orthostatic challenge. The noninclusion criteria were any general unstable medical condition incompatible with orthostatic challenge, having no temporal acoustic window, severe cognitive impairment (Mini Mental Status Examination <15), history of stroke, and legal guardianship. We used the novel and highly sensitive ultrasound technique of tissue pulsatility imaging to measure BTP changes in elderly patients with (n = 22) and without OH (n = 17) during an orthostatic challenge. We found that the mean brain tissue pulsatility related to global intracranial pulsatility, but not maximum brain tissue pulsatility related to large arteries pulsatility, decreased significantly in OH patients, with a delay compared with the immediate drop in peripheral blood pressure. Global pulsatile CBF changes and small vessels pulsatility, rather than changes in only large arteries, may be key mechanisms in OH to account for the links between OH and cerebrovascular disorders.

Evaluation of the Temporal Acoustic Window for Transcranial Doppler in a Multi-Ethnic Population in Brazil

The aim of this study was to relate the presence of a temporal acoustic window (TAW) to the variables sex, age and race. This observational study was conducted in patients under etiologic investigation after stroke, sickle-cell anemia and hospitalization in an intensive therapy neurologic unit. TAW presence was confirmed by bilateral assessment by two neurologists via transcranial Doppler (TCD). Multiple logistic regression was performed to explain the presence of the window as a function of sex, age and race. In 20% of the 262 patients evaluated, a TAW was not present. The incidence of TAW presence was greater in men (odds ratio [OR] = 5.4, 95% confidence interval [CI] = 2.5–11.7, p < 0.01); lower with increased age (OR = 0.9, 95% CI = 0.92–0.97, p < 0.01); and lower among those of African and Asian descent (OR = 0.32, 95% CI = 0.14–0.70, p = 0.005). On the basis of the results, more men than women had TAWs, and the decrease in TAWs was associated with increased age and African or Asian descent.

PO-0422 Evaluation Of Cerebral Perfusion In Small For Gestational Age Neonates In The First Postnatal Week Using Colour Doppler Sonography

Background and aims Small for gestational age neonates (SGA) living in conditions of chronic hypoxia during fetal life may develop different autoregulation mechanisms in cerebral perfusion in order to maintain oxygen delivery to the brain in comparison to appropriate for gestational age (AGA) neonates. The aim of the current study was to estimate brain perfusion in SGA neonates during first postnatal week with the use of colour Doppler sonography. Patients/methods Transcranial Doppler sonography from the temporal acoustic window was performed bilaterally with CX50 PHILIPS device using S8–3 transducer in the first, third and seventh day of life of SGA neonates with mean gestational age 31.6 ± 2.2w and to comparable AGA ones. Recorded parameters were Peak Systolic Velocity (PSV), End Diastolic Velocity (EDV), Mean Velocity (MV), Pulsatility Index (PI) and Resistance Index (RI) in middle cerebral artery MCA. Results 26 SGA and 26 matched for GA control AGA neonates were prospectively enrolled with statistically significant difference in birth weight (1.201, 9 ± 369.1 vs 1.805, 3 ± 431.7, p Conclusion Increased brain metabolism in the first postnatal days is responsible for the observed augmentation of cerebral perfusion in order to maintain the balance between oxygen delivery and consumption. It seems that SGA neonates manage to develop compensatory mechanisms probably with an increase of their brain perfusion.

Simultaneous Bilateral Real-Time 3-D Transcranial Ultrasound Imaging at 1 MHz Through Poor Acoustic Windows

Ultrasound imaging has been proposed as a rapid, portable alternative imaging modality to examine stroke patients in pre-hospital or emergency room settings. However, in performing transcranial ultrasound examinations, 8%–29% of patients in a general population may present with window failure, in which case it is not possible to acquire clinically useful sonographic information through the temporal bone acoustic window. In this work, we describe the technical considerations, design and fabrication of low-frequency (1.2 MHz), large aperture (25.3 mm) sparse matrix array transducers for 3-D imaging in the event of window failure. These transducers are integrated into a system for real-time 3-D bilateral transcranial imaging—the ultrasound brain helmet—and color flow imaging capabilities at 1.2 MHz are directly compared with arrays operating at 1.8 MHz in a flow phantom with attenuation comparable to the in vivo case. Contrast-enhanced imaging allowed visualization of arteries of the Circle of Willis in 5 of 5 subjects and 8 of 10 sides of the head despite probe placement outside of the acoustic window. Results suggest that this type of transducer may allow acquisition of useful images either in individuals with poor windows or outside of the temporal acoustic window in the field.

Contrast-Enhanced Ultrasound Ventriculography

During external ventricular drainage (EVD) weaning, cranial computed tomography (cCT) is necessary to evaluate ventricle width. Because intrahospital transfer of critically ill patients is associated with higher mortality, bedside techniques are necessary to evaluate ventricle width. Transcranial sonography is able to show the ventricles in patients with sufficient temporal acoustic window. Contrast-enhanced ultrasound (CEUS) is able to overcome the limitations of insufficient insonation. We demonstrate the feasibility of bedside transcranial CEUS ventriculography to measure ventricles and verify the passage of cerebrospinal fluid (CSF) through the foramen of Magendie into the subarachnoid space during EVD weaning in critically ill patients. Six patients were examined by transcranial and transnuchal CEUS. Harmonic imaging with low mechanical index was used. One milliliter of an ultrasound contrast agent was administered via EVD line. Comparison with the cCT scans at the time of discharge was used to confirm CEUS-ventriculography results. Ventricles were visualized in all patients. CSF transmission via the foramen of Magendie was demonstrated in 5 patients. Mean ventricle width (centimeters) was 0.67 (CEUS) vs 0.73 (cCT) (standard deviation 0.43, 0.45, P = .116) [third ventricle], 0.88 vs 1.02 (0.28, 0.22, P = .055) [fourth ventricle], 1.40 vs 1.37 (0.56, 0.54, P = .620) [left lateral ventricle], 1.37 vs 1.37 (0.55, 0.54, P = .952) [right lateral ventricle], 2.33 vs 2.23 (0.51, 0.58, P = .169) [left anterior horn], and 2.25 vs 2.07 (0.56, 0.64, P = .204) [right anterior horn]. Mean duration for CEUS ventriculography was 3:15 minutes. CEUS ventriculography is an effective bedside procedure in critically ill patients with EVD. CEUS allows measurement of ventricle width, ventricle communication, and CSF transfer to the subarachnoidal space through the cisternal foramina.

Ipsilateral evaluation of the transverse sinus: Transcranial color-coded sonography approach in comparison with magnetic resonance venography

The ultrasound examination of intracranial venous structures by transcranial color-coded sonography (TCCS) is a validated and standardized application. Similarly some intracranial venous sinuses are known for their relatively low insonation rate, as straight sinus (SRS) and transverse sinus (TS), ranging from 35% to 73%. The relatively high frequency of hypoplasia of TS can partially take account for these data. The aim of this study is to evaluate the feasibility of this approach in a standard TCCS examination, in comparison with magnetic resonance (MR) findings by using the Virtual Navigator system. The standardized approach to the TS was a contralateral insonation, starting to the SRS plane and angulating downwards the probe. In this way it is possible to insonate the proximal segment of the contralateral TS. We proposed a new approach with an extreme downwards tilting and a slow opposite angulation of the probe for examining the ispilateral TS. Forty consecutive subjects were chosen among patients who underwent standard TCCS examinations at our lab and had a suitable temporal acoustic window, and a recently performed MR venography. The contralateral TS insonation rate was compared with the ipsilateral one. The insonation rate was 61/80 (76.25%) for the contralateral TS and 75/80 (93.75%) for the ipsilateral approach. Two of 5 not detectable TS were aplasic in MR venography and the others were not identified by a poor acoustic window. The ipsilateral approach could be associated to the contralateral standard study for insonating the TS.

Virtual Navigator study: Subset of preliminary data about cerebral venous circulation

Neuroradiological techniques are known for their high spatial resolution in imaging of intracranial structures, in comparison with neurosonological techniques (TCCS), known for their high temporal resolution. An ideal study of intracranial circulation should combine the high temporal resolution of ultrasound with the high spatial resolution of Magnetic Resonance (MR) Imaging. This imaging fusion system is actually used for the ultrasound liver examination and it is known as Virtual Navigator. Therefore we implemented this system for the examination of the intracranial venous hemodynamics. Fifteen consecutive subjects (7 men and 8 women, mean age 51.5 ± 8.64 years) were chosen among patients who underwent standard TCCS examinations at our lab and had age >18 years, a suitable temporal acoustic window and a recently performed intracranial MR venography. The axial scanning approach was used from the temporal window and the standard TCCS examination was compared with the Virtual Navigator examination, for the insonation rate of the basal vein of Rosenthal (BVR), Galen vein (GV), Straight sinus (SRS) and Transverse sinus (TS). The insonation rates of the venous structures are only slightly improved for BVR (from 90% to 96.67%) but are substantially increased for SRS and TS (for this last one from 63.33% to 86.67%) with a statistically significant difference (p < 0.05). The Virtual Navigator protocol can help to insonate the intracranial venous system.

Accuracy of transcranial colour-coded sonography in the diagnosis of anterior cerebral artery vasospasm

Background and purposeTranscranial colour-coded sonography (TCCS) has been proven to be a method of high performance in the diagnosis of spasm of the middle cerebral artery (MCA). Relevant data concerning the anterior cerebral artery (ACA) varies amongst studies. The aim of this study was to assess the performance of TCCS in the diagnosis of spasm affecting the ACA. Material and methodsNinety-two patients (39 women and 53 men, age 51 ± 12.1 years) were examined using TCCS before cerebral angiography. Of 184 examined ACAs, only 133 arteries could be visualized due to insufficiency of the temporal acoustic window. Therefore, only 15 out of 25 arteries in which vasospasm was diagnosed with angiography (by two neuroradiologists not informed about the sonographic findings) could be included in the analysis. Receiver operating characteristic (ROC) curves were constructed for specific blood flow velocities: peak systolic (PSV), mean (M) and end-diastolic (EDV). The area under the ROC curve was used to measure the overall diagnostic performance of TCCS. ResultsThe area under the ROC curve for PSV was 0.83, which indicates good performance. The PSV threshold of 98 cm/s corresponded to maximum accuracy and was associated with 71% sensitivity vs. 88% specificity. Average systolic blood flow velocity in the vessels with vasospasm was 129 cm/s, whereas in unaffected vessels it was 76 cm/s. ConclusionsThe accuracy of TCCS in the diagnosis of ACA spasm is relatively high – the value of the area under the ROC amounts to 0.83. PSV performs best and the threshold of 98 cm/s is associated with an optimal trade-off between sensitivity and specificity.

Induced hypothermia in adult community-acquired bacterial meningitis – more than just a possibility?

We present the case series of adult community-acquired bacterial meningitis treated with hypothermia. The major criteria for therapeutic hypothermia (TH) was impaired carbon dioxide reactivity (CO(2)R) assessed by Transcranial Doppler (TCD). In patients without temporal acoustic window, minor criteria (optic nerve sheath diameter ≥ 6.0 mm plus GCS ≤ 8) were required. According to our, although limited experience, the use of mild hypothermia in selected patients with community-acquired bacterial meningitis accompanied with appropriate monitoring could be a promising treatment tool.

Bedside detection of acute epidural hematoma by transcranial sonography in a head-injured patient

Sir: A 24 year-old boy was brought to the ED with head injury after a motorcycle accident. On his arrival, he was alert, and his GCS was 14 (V5, M5, E4). A head CT scan was performed, and a small (max width 0.9 cm) temporal epidural hematoma was observed. Since its small dimension, it was not scheduled for surgery, and a new CT scan after 4 h was planned. Transcranial echography (TCE) was performed with a 2.0 MHz transducer insonating in a transverse plane through the temporal acoustic bone window: after identifying the arteries of the circle of Willis, the depth of the insonation window was adjusted (usually 16 cm), so that the butterfly-shaped mesencephalic brainstem and the contralateral skull became visible [1]. In these conditions an epidural hematoma was observed as an hyperechogenic image just inside the skull (Fig. 1). One hour later, the clinical condition was unchanged. TCE was repeated, and an enlargement of the hematoma with a maximum width of 2.5 cm (Fig. 1). CT scan was immediately performed, and the enlargement was confirmed. The hematoma was promptly evacuated, and 7 days later the patient was discharged from the hospital with no neurological deficit. Recently, transcranial sonography of brain parenchyma in adults has been proposed by several authors for the evaluation of the ventricular system, monitoring of midline shift, diagnosis and follow-up of intracranial mass lesions. Seidel G et al. [2] found a good correlation between CT and TCE in the measurements of third (r = 0.83, P \ 0.0001) and lateral ventricles (r = 0.73, P \ 0.0001). Similar agreement between these two imaging techniques were observed by Tang et al. [3] in the measurement of midline shift (gamma = 0.91, P \ 0.01). Maurer et al. [4] used TCE to differentiate ischemic from hemorrhagic stroke. On 151 patients, 18 (12%) had no sufficient acoustic bone window. Of the remaining 133 patients, they observed that a correct sonographic diagnosis was made in the 95% of the cases (126 patients). To our knowledge, this is the first report that shows echographical finding of acute epidural hematoma in adults. Actually, we found that, thanks to the improvement of technology of ultrasound machines, high resolution images of the contralateral skull may be often obtained by the transtemporal approach, so that epidural mass lesion can be rapidly detected by trained physicians. According with recent guidelines [5], morphologic criteria for surgery are based on the volume and thickness of the hematoma, and on the extent of midline shift. All these data may be obtained by transcranial sonography that can be used bedside, together with CT scan, to monitor these patients in case of non-operative management. In conclusion, in our opinion transcranial echography may be a useful tool to monitor epidural hematomas before clinical conditions deteriorate. In all patients with a sufficient acoustic window in the temporal bone, it is a rapid and noninvasive neuroimaging technique that can complement the results of CT scan, and may help to reduce delays in surgical management. Further prospective studies are needed to evaluate sensitivity, specificity and accuracy of this technique

Response to Letter by Tsivgoulis et al

Response: We greatly appreciate the interest shown by Tsivgoulis and colleagues in their letter commenting on our recent article about the sex differences in the impact of metabolic syndrome (MetS) on the response to intravenous thrombolysis for acute middle cerebral artery (MCA) ischemic stroke.1 In our study, performed in a series of 125 consecutive patients with a documented acute MCA occlusion who were treated with intravenous tissue plasminogen activator (t-PA) according to SITS-MOST criteria, we observed that the effect of MetS enhancing the resistance to thrombolysis seemed to be more pronounced in women than in men.2 In this response we will try to address the valuable criticisms raised by Tsivgoulis et al in their letter. The first comment refers to the use of echo-contrast agents in patients without an adequate temporal acoustic window precluding transcranial Doppler (TCD) assessment of MCA. We agree with the authors that contrast agents influence residual flow signatures by artificially increasing velocities detected by TCD, the so-called “blooming effect.”3 This being true, we believe that this methodological issue is not likely to have …

Tissue Pulsatility Imaging of Cerebral Vasoreactivity During Hyperventilation

Tissue pulsatility imaging (TPI) is an ultrasonic technique that is being developed at the University of Washington to measure tissue displacement or strain as a result of blood flow over the cardiac and respiratory cycles. This technique is based in principle on plethysmography, an older nonultrasound technology for measuring expansion of a whole limb or body part due to perfusion. TPI adapts tissue Doppler signal processing methods to measure the “plethysmographic” signal from hundreds or thousands of sample volumes in an ultrasound image plane. This paper presents a feasibility study to determine if TPI can be used to assess cerebral vasoreactivity. Ultrasound data were collected transcranially through the temporal acoustic window from four subjects before, during and after voluntary hyperventilation. In each subject, decreases in tissue pulsatility during hyperventilation were observed that were statistically correlated with the subject's end-tidal CO 2 measurements. (E-mail: kucewicz@u.washington.edu)

Contrast-Enhanced Transcranial Color-Coded Duplex Sonography Versus Computed Tomography and Magnetic Resonance Angiography in the Follow-up of Basilar Stenting

The annual risk of stroke in patients with basilar artery stenosis is 2.5% to 11%, and even despite aggressive medical treatment, the prognosis of basilar artery thrombosis is fatal. For these reasons, invasive therapeutic approaches have been developed for cases of stroke due to vertebrobasilar circulation stenosis and occlusion. 1 In specialized centers, both intra-arterial thrombolysis performed in cases of basilar occlusion and intracranial stenting nowadays are becoming available suitable procedures to restore vascularization in cases of vertebrobasilar stenosis. 2,3 Nonetheless, restenosis is the major complication, with rates of 30% to 41% and an overall annual periprocedural complication rate of 6.6%. 4,5 It is therefore important to perform an accurate postprocedural follow-up to determine stent lumen patency. Conventional digital subtraction angiography (DSA) is still the most sensitive technique for visualizing the residual lumen after stenting, but it is invasive and not free of complications. Postprocedural follow-up is then usually performed by computed tomographic angiography (CTA) or magnetic resonance angiography (MRA). These techniques are both expensive and have limitations due to stent-induced artifacts, which may hide the residual lumen. 2 Transcranial color-coded duplex sonography (TCCD) has been a well-established diagnostic tool for visualization of the basal cerebral arteries since the early 1990s, although it is limited by the quality of the temporal acoustic bone window.6 With the introduction of sonographic contrast agents, vessel visualization has become easier and feasible in daily practice, at the bedside of the patient, with low costs and excellent results. 7 We report a case of a patient with a stroke and basilar artery stenosis who underwent a stenting procedure and follow-up studies with MRA, CTA, DSA, and TCCD.

The Thickness and Texture of Temporal Bone in Brain CT Predict Acoustic Window Failure of Transcranial Doppler

Although transcranial Doppler (TCD) is useful for evaluation and treatment of ischemic stroke, temporal acoustic window failure (TAWF) limits its application. We performed this study to reveal whether initial brain CT of acute stroke patients predicted TAWF. We performed TCD in 92 acute ischemic stroke patients (57 males, aged 38-84 years) with brain CT scans. We measured the thickness (BTW) and evaluated the texture of the temporal bone in acoustic windows shown in the CT scan with the use of picture archiving and communication system. The bone mineral density (BMD) of the vertebral bodies, femurs, and whole body was also measured. Doppler signals were adequately obtained in 121 (65.8%) of the 184 middle cerebral arteries (MCA) from both cerebral hemispheres. BTW and inhomogeneity of temporal bone, besides age, sex, and hypercholesterolemia, was strongly correlated with TAWF. BMD was not directly correlated with TAWF, but inhomogeneous temporal bone was correlated with lower BMD scores. If the brain CT scan showed thick (BTW >or= 2.7 mm) and inhomogeneous temporal bone, the possibility of TAWF was 93.5%, while if brain CT scan showed thin (BTW < 2.7 mm) and homogenous temporal bone, it was only 5.4%. The texture as well as the thickness of the temporal bone was the most important determinant of TAWF. When acute stroke patients had thin and homogeneous temporal bones in initial brain CT scan, TAWF was very rare, and loss of MCA signals on TCD specifcally indicated the absence of blood flow in MCA.

Doppler transcraniano convencional em voluntários assintomáticos: variabilidade e valores de referência para parâmetros de fluxo sanguíneo

To establish reference values for measures of blood flow velocities and impedance indexes in healthy individuals through conventional transcranial Doppler (TCD) and to observe their variations in relation to the age and sex. 88 asymptomatic volunteers were examined without antecedents of cardiac, peripheral or cerebrovascular diseases. The TCD were accomplished by the same examiner. The middle, anterior and posterior cerebral arteries were studied through the temporal acoustic window and the vertebral and basilar arteries through the suboccipital acoustic window. The values of mean velocity (MV), peak-systolic velocity (PSV), final diastolic velocity (FDV), resistance index (RI) and pulsatility index (PI) of each examined arterial segment were filed. The reference limits found by us were similar to the described by other authors for all of the studied parameters. There was tendency of the flow velocities decrease and of the impedance indexes increase with moving forward of the age. The values of velocities in the women were superior to the found in men. TCD was shown useful in the evaluation of hemodynamic cerebral for our population. Our results are similar to the other studies, so much in the reference values as in relationship with the age and the sex.

Detection of Cardiac Right-to-Left Shunts by Contrast-Enhanced Harmonic Carotid Duplex Sonography

Paradoxical embolization by cardiac right-to-left shunts (RLS) is increasingly recognized as an important factor for embolic stroke. Contrast-enhanced transcranial Doppler sonography (ce-TCDS) is an established diagnostic tool for RLS detection but is frequently limited because of an inadequate temporal acoustic bone window. The purpose of this study was to determine whether extracranial sonography (ECS) using harmonic frequencies improves detection of RLS. Extracranial color duplex sonography using harmonic frequencies enables visualization of even single ultrasound contrast agent microbubbles because of oscillation. Patients with stroke and positive RLS findings on transesophageal echocardiography underwent a simultaneous extracranial and transcranial sonographic examination of the proximal common carotid artery (CCA) and middle cerebral artery (MCA) on the same side. A Valsalva strain was performed for 10 seconds after intravenous bolus injection of a galactose-based nontranspulmonary contrast agent. The B-mode frame sequences of the transverse plane of the CCA obtained by harmonic ECS and the ce-TCDS recordings of high-intensity transient signals from the MCA were analyzed offline. In all patients with RLS, the shunts could be identified by harmonic ECS. A close correlation could be seen between the count of visualized microbubbles in the CCA and the number of high-intensity transient signals detected on ce-TCDS in the ipsilateral MCA. The results of this study indicate that contrast-enhanced ultrasound harmonic imaging of the CCA using a Valsalva strain might be an optional screening tool for detection of cardiac RLS in patients with insufficient acoustic bone windows.