Detection of a pituitary macroadenoma with transcranial ultrasonography: Principles and potential clinical applications

Transcranial color-coded duplex sonography (TCCS) allows to study intracranial vessels through the intact skull, but the visualization of normal and pathologic brain structures in adults is often suboptimal due to inadequate acoustic window. The full potential of TCCS for clinical practice remains unfulfilled. Here, we describe the ability of TCCS to detect a non-functioning pituitary macroadenoma in a 58-year-old man affected by headache. The macroadenoma was visualized as a roundish, well-defined mass, mildly hyperechogenic compared to the hypoechogenic mesencephalic brainstem but mainly hypoechogenic compared to the surrounding intracranial structures. Intracranial vessels represented useful landmarks. Using tissue harmonic imaging mode, the borders of the macroadenoma were visualized more clearly. Macroadenoma characteristics were confirmed by magnetic resonance imaging. Neurosonologists should be aware of the possibility to incidentally find, during routinary TCCS, pituitary macroadenomas or other brain tumors (as incidentalomas), worthy to be recognized and referred for further investigations.

Acoustic properties across the human skull

Transcranial ultrasound is emerging as a noninvasive tool for targeted treatments of brain disorders. Transcranial ultrasound has been used for remotely mediated surgeries, transient opening of the blood-brain barrier, local drug delivery, and neuromodulation. However, all applications have been limited by the severe attenuation and phase distortion of ultrasound by the skull. Here, we characterized the dependence of the aberrations on specific anatomical segments of the skull. In particular, we measured ultrasound propagation properties throughout the perimeter of intact human skulls at 500 kHz. We found that the parietal bone provides substantially higher transmission (average pressure transmission 31 ± 7%) and smaller phase distortion (242 ± 44 degrees) than frontal (13 ± 2%, 425 ± 47 degrees) and occipital bone regions (16 ± 4%, 416 ± 35 degrees). In addition, we found that across skull regions, transmission strongly anti-correlated (R=-0.79) and phase distortion correlated (R=0.85) with skull thickness. This information guides the design, positioning, and skull correction functionality of next-generation devices for effective, safe, and reproducible transcranial focused ultrasound therapies.

Transcranial Doppler Screening in a Current Cohort of Children With Sickle Cell Anemia: Results From the DISPLACE Study

Stroke prevention guidelines for sickle cell anemia (SCA) recommend transcranial Doppler (TCD) screening to identify children at stroke risk; however, TCD screening implementation remains poor. This report describes results from Part 1 of the 28-site DISPLACE (Dissemination and Implementation of Stroke Prevention Looking at the Care Environment) study, a baseline assessment of TCD implementation rates. This report describes TCD implementation by consortium site characteristics; characteristics of TCDs completed; and TCD results based on age. The cohort included 5247 children with SCA, of whom 5116 were eligible for TCD implementation assessment for at least 1 study year. The majority of children were African American or Black, non-Hispanic and received Medicaid. Mean age at first recorded TCD was 5.9 and 10.5 years at study end. Observed TCD screening rates were unsatisfactory across geographic regions (mean 49.9%; range: 30.9% to 74.7%) independent of size, institution type, or previous stroke prevention trial participation. The abnormal TCD rate was 2.9%, with a median age of 6.3 years for first abnormal TCD result. Findings highlight real-world TCD screening practices and results from the largest SCA cohort to date. Data informed the part 3 implementation study for improving stroke screening and findings may inform clinical practice improvements.

Associations Between Transcranial Doppler Flow Velocities, Laboratory Parameters, and Clinical Features in Turkish Children With Sickle Cell Disease

OBJECTIVE

Stroke is one of the major complications of sickle cell disease (SCD). Stroke features either occlusion of, or stenosis at, the origin of one of the large intracerebral arteries, the internal carotid artery (ICA), and/or the middle cerebral artery (MCA).

PURPOSE

We sought correlations between cerebral blood flow velocities and the laboratory and clinical findings of patients with SCD.

MATERIALS AND METHODS

Fifty-three pediatric SCD patients (39 with HbSS, 14 with HbSβ0) were analyzed. The mean patient age was 12.9±3.9 years. The control group contained 24 healthy individuals. The time-averaged maximum mean velocity (TAMMV) and resistive index (RI) of the MCA, the TAMMVs of the ICA and vertebral artery (VA), and the diameter of the VA were estimated through transcranial Doppler ultrasonography using a 2.5 MHz transducer, in accordance with the Stroke Prevention Trial in Sickle Cell Anemia (STOP) protocol. We evaluated the relationships between the TAMMVs, laboratory parameters, and clinical findings.

RESULTS

The mean±SD MCA TAMMV was 161.2±35.4 cm/s in patients with HbSS and 185.8±62.9 cm/s in patients with HbSβ0. The mean MCA TAMMV, RI, ICA TAMMV, VA TAMMV, and VA diameter were 168.5±43.9 cm/s, 0.63±0.06, 116.8±25.5 cm/s, 69.2±18.5 cm/s, and 3.5±0.61 mm for all SCD patients, respectively. In the control group, the mean MCA TAMMV, RI, ICA TAMMV, VA TAMMV, and VA diameter were 103.8±28.8 cm/s, 0.53±0.04, 96.4±27.8 cm/s, 40.3±12.1 cm/s, and 3.4±0.6 mm, respectively. Although the differences were not significant, TAMMVs were higher in HbSβ0 patients taking hydroxyurea; those with hemoglobin levels <8 g/dL, ferritin levels >1000 ng/dL, mean platelet volume >12 fL, or red cell distribution width >18%; or required chelation, or were below the third percentiles of weight and height. The TAMMV was significantly higher only in SCD patients who complained of headache.

CONCLUSIONS

High ferritin and low hemoglobin levels, a high mean platelet volume, a high red cell distribution width, low weight (below the third percentile), and a short height (below the third percentile) may be associated with elevated cerebral blood flow velocities and an increased stroke risk in children with SCD. Children with such features should be closely followed-up through transcranial Doppler ultrasonography examination.

The Frontal Bone Window for Transcranial Doppler Ultrasonography in Critically Ill Patients: Validation of a New Approach in the ICU

BACKGROUND AND OBJECTIVE

The temporal bone window (TBW) for transcranial Doppler (TCD) often fails to insonate the anterior cerebral artery (ACA). The frontal bone window (FBW) has never been evaluated in intensive care units (ICU). The main objective was to determine the ability of the FBW to assess ACA velocities in critically ill patients.

METHODS

A prospective study was conducted in two ICUs of the Montpellier University Hospital (France), between November 2014 and September 2016. Adult patients admitted to ICU for brain injury, with a Glasgow Coma Scale score ≤ 13, were enrolled within 3 days after admission. A first TCD examination was carried out bilaterally through the TBW and FBW by an intensivist expert in TCD, repeated by the same examiner, and 15 min later by an intensivist certified in TCD, designated as non-expert, blinded. The success of the FBW examinations was defined by the ability to measure the ACA velocities. Intra- and interobserver agreements were analyzed according to the Bland and Altman method.

RESULTS

A total of 147 patients were analyzed. The FBW succeeded in insonating the ACA in 66 patients [45%, CI (37-53)], 45 bilaterally and 21 unilaterally. For 16 patients (11%), the FBW was the only way to measure ACA velocities. By combining the two techniques, the ACA success rate increased from 62% CI (54-70) to 73% CI (65-79) (P = 0.05). Intra- and interobserver mean biases and 95% limits of agreement for ACA systolic velocity measurements through the FBW were 1 (- 33 to 35) and 2 (- 34 to 38) cm s^-1, respectively. For paired TBW and FBW measures of ACA velocities, mean biases (± SD) for ACA systolic, and mean and diastolic velocities were relatively close to zero, but negatives (- 7 ± 33, - 2 ± 19, - 1 ± 15 cm s^-1, respectively), highlighting that ACA velocities were lower with the FBW (A2 segment) than TBW (A1 segment). The correlation coefficient for ACA systolic velocities measured by the FBW and TBW was R = 0.47, CI (0.28-0.62). No risk factors for failure of the FBW were identified.

CONCLUSIONS

In ICU, the FBW was able to insonate the ACA in 45% of patients admitted for brain injury, without the use of contrast agents. The FBW could improve the detection of ACA vasospasms.

Association between Tomographic Characteristics of the Temporal Bone and Transtemporal Window Quality on Transcranial Color Doppler Ultrasound in Patients with Stroke or Transient Ischemic Attack

Transcranial color-coded Doppler (TCCD) is an ultrasonographic technique used to obtain and evaluate images of the cerebral parenchyma and to assess blood flow velocities of the intracranial vessels. One of the major limitations of TCCD is the failure to insonate through the transtemporal window, which occurs in about 5%-44% of patients. Temporal bone thickness has been strongly associated with transtemporal window failure (TWF). The aims of the study were to evaluate the association between TWF on TCCD and radiologic findings on computed tomography of the skull along with the demographic characteristics of patients with acute stroke or transient ischemic attack (TIA), and to propose a classification for transcranial window quality (TWQ) on B-mode scan of TCCD. A total of 187 consecutive patients with acute stroke or TIA were included. Among them, 21.9% had TWF and 34.8% had TWQ categorized as insufficient on B-mode scan of TCCD. On logistic regression, age (odds ratio [OR] = 1.07, 95% confidence interval [CI]: 1.03-1.12, p < 0.001), female sex (OR = 5.99, 95% CI: 2.09-17.16, p = 0.001), pneumatized temporal bone (OR = 7.90, 95% CI: 1.95-32.03, p = 0.004) and temporal bone thickness (OR = 3.04, 95% CI: 1.73-5.35, p < 0.001) were independent predictors of TWF, even after adjusting for confounders. These findings may help to select patients in whom echogenic contrast or even other imaging methods could be used to assess intracranial vessels.

Pilot Study to Characterize Middle Cerebral Artery Dynamic Response to an Acute Bout of Moderate Intensity Exercise at 3- and 6-Months Poststroke

Background The primary aim of this study was to characterize the middle cerebral artery blood velocity (MCAv) dynamic response to an acute bout of exercise in humans at 3- and 6-months poststroke. As a secondary objective, we grouped individuals according to the MCAv dynamic response to the exercise bout as responder or nonresponder. We tested whether physical activity, aerobic fitness, and exercise mean arterial blood pressure differed between groups. Methods and Results Transcranial Doppler ultrasound measured MCAv during a 90-second baseline followed by a 6-minute moderate intensity exercise bout. Heart rate, mean arterial blood pressure, and end-tidal CO2 were additional variables of interest. The MCAv dynamic response variables included the following: baseline, time delay, amplitude, and time constant. Linear mixed model revealed no significant differences in our selected outcomes between 3- and 6-months poststroke. Individuals characterized as responders demonstrated a faster time delay, higher amplitude, and reported higher levels of physical activity and aerobic fitness when compared with the nonresponders. No between-group differences were identified for baseline, time constant, or exercise mean arterial blood pressure. In the nonresponders, we observed an immediate rise in MCAv following exercise onset followed by an immediate decline to near baseline values, while the responders showed an exponential rise until steady state was reached. Conclusions The MCAv dynamic response profile has the potential to provide valuable information during an acute exercise bout following stroke. Individuals with a greater MCAv response to the exercise stimulus reported statin use and regular participation in exercise.

Temporal evolution of neurovascular coupling recovery following moderate- and high-intensity exercise

PURPOSE

Studies examining neurovascular coupling (NVC) require participants to refrain from exercise for 12-24 hours. However, there is a paucity of empirical evidence for this restriction. The objectives for this study were to delineate the time-course recovery of NVC metrics following exercise and establish the NVC within- and between-day reliability.

METHODS

Nine participants completed a complex visual search paradigm to assess NVC via transcranial Doppler ultrasound of the posterior cerebral artery blood velocity (PCA). Measurements were performed prior to and throughout the 8-hour recovery period following three randomized conditions: 45 minutes of moderate-intensity exercise (at 50% heart-rate reserve), 30 minutes high-intensity intervals (10, 1-minute intervals at 85% heart-rate reserve), and control (30 minutes quiet rest). In each condition, baseline measures were collected at 8:00am with serial follow-ups at hours zero, one, two, four, six, and eight.

RESULTS

Area-under-the-curve and time-to-peak PCA velocity during the visual search were attenuated at hour zero following high-intensity intervals (all p < 0.05); however, these NVC metrics recovered at hour one (all p > 0.13). Conversely, baseline PCA velocity, peak PCA velocity, and the relative percent increase were not different following high-intensity intervals compared to baseline (all p > 0.26). No NVC metrics differed from baseline following both moderate exercise and control conditions (all p > 0.24). The majority of the NVC parameters demonstrated high levels of reliability (intraclass correlation coefficient: >0.90).

CONCLUSION

Future NVC assessments can take place a minimum of one hour following exercise. Moreover, all metrics did not change across the control condition, therefore future studies using this methodology can reliably quantify NVC between 8:00am and 7:00 pm.

Transcranial Color-Coded Sonography Criteria for Moderate and Severe Middle Cerebral Artery Stenosis

This study aimed to establish optimal criteria for evaluation of moderate (50%-69%) and severe (70%-99%) middle cerebral artery (MCA) stenosis with transcranial color-coded sonography (TCCS). A total of 375 cases provided 409 TCCS/digital subtraction angiography vessel pairs. Peak systolic velocity (PSV), end-diastolic velocity (EDV) and mean flow velocity (MFV) of the MCA were measured. The stenotic/distal MFV ratios (SDRs) were calculated. With digital subtraction angiography as a reference, for 50%-69% MCA stenosis, the optimal combined criteria were PSV ≥180 cm/s (sensitivity 95.7%, specificity 64.9% and overall accuracy 69.7%); EDV ≥75 cm/s (90.0%, 66.4% and 68.7%); MFV ≥110 cm/s (95.7%, 64.0% and 69.4%); and SDR ≥2.5 (88.6%, 71.3% and 76.3%). Criteria for 70%-99% MCA stenosis were PSV ≥240 cm/s (93.5%, 89.9% and 85.5%); EDV ≥100 cm/s (96.8%, 89.0% and 87.3%); MFV≥160 cm/s (91.9%, 92.8% and 92.2%); and SDR ≥4 (87.1%, 92.2% and 91.4%). Parameters of the MCA detected by TCCS, especially SDR, may increase accuracy in diagnosis of 50%-69% and 70%-99% MCA stenosis.

The reliability of a breath-hold protocol to determine cerebrovascular reactivity in adolescents

PURPOSE

Cerebrovascular reactivity (CVR) is impaired in adolescents with cardiovascular disease risk factors. A breath-hold test is a noninvasive method of assessing CVR, yet there are no reliability data of this outcome in youth. This study aimed to assess the reliability of a breath-hold protocol to measure CVR in adolescents.

METHODS

Twenty-one 13 to 15 year old adolescents visited the laboratory on two separate occasions, to assess the within-test, within-day and between-day reliability of a breath-hold protocol, consisting of three breath-hold attempts. CVR was defined as the relative increase from baseline in middle cerebral artery mean blood velocity following a maximal breath-hold of up to 30 seconds, quantified via transcranial Doppler ultrasonography.

RESULTS

Mean breath-hold duration and CVR were never significantly correlated (r < .31, P > .08). The within-test coefficient of variation for CVR was 15.2%, with no significant differences across breath-holds (P = .88), so the three breath-hold attempts were averaged for subsequent analyses. The within- and between-day coefficients of variation for CVR were 10.8% and 15.3%, respectively.

CONCLUSIONS

CVR assessed via a three breath-hold protocol can be reliably measured in adolescents, yielding similar within- and between-day reliability. Analyses revealed that breath-hold length and CVR were unrelated, indicating the commonly reported normalization of CVR to breath-hold duration (breath-hold index) may be unnecessary in youth.

Is it coincidental or correlative between reversible splenial lesion syndrome and atrial septal defect?: A case report

RATIONALE

Reversible splenial lesion syndrome (RESLES) is a recently identified clinico-radiological syndrome, the etiology is miscellaneous. Atrial septal defect (ASD) as an underlying etiology for RESLES has not been reported. We first report a rare case of RESLES associated with ASD. The clinical, radiological, and ultrasonic profiles were presented and the pathophysiological mechanism was analyzed.

PATIENT CONCERNS

A 23-year-old man presented with headache, drowsiness, occasional paraphasia, and paroxysmal dry cough. Brain magnetic resonance imaging (MRI) on admission showed an ovoid isolated lesion in the splenium of corpus callosum, which exhibited hyperintensity on diffusion-weighted imaging and hypointensity on apparent diffusion coefficient, and completely disappeared on the follow-up MRI 14 days later. ASD was found by transthoracic echocardiography, Right-to-left shunts were detected on color Doppler of transesophageal echocardiography, and microemboli were captured by transcranial Doppler ultrasound.

DIAGNOSES

According to his clinical history and imaging results, we confirmed the diagnosis of RESLES associated with ASD.

INTERVENTIONS

The patient was treated by oral aspirin and lopidogrel sulfate to inhibit platelet aggregation. In addition, oral nimodipine to suppress vasoconstriction.

OUTCOMES

After 14 days treatment, all the symptoms presenting on admission resolved completely. Subsequently, a repair surgery of ASD under thoracoscopy was successfully performed.

LESSONS

To our knowledge, this is the first reported case of ASD may be an underlying etiology for RESLES and need require an etiotropic treatment.

Ultrasound Technologies for Imaging and Modulating Neural Activity

Visualizing and perturbing neural activity on a brain-wide scale in model animals and humans is a major goal of neuroscience technology development. Established electrical and optical techniques typically break down at this scale due to inherent physical limitations. In contrast, ultrasound readily permeates the brain, and in some cases the skull, and interacts with tissue with a fundamental resolution on the order of 100 μm and 1 ms. This basic ability has motivated major efforts to harness ultrasound as a modality for large-scale brain imaging and modulation. These efforts have resulted in already-useful neuroscience tools, including high-resolution hemodynamic functional imaging, focused ultrasound neuromodulation, and local drug delivery. Furthermore, recent breakthroughs promise to connect ultrasound to neurons at the genetic level for biomolecular imaging and sonogenetic control. In this article, we review the state of the art and ongoing developments in ultrasonic neurotechnology, building from fundamental principles to current utility, open questions, and future potential.

Evaluation on the application of transcranial Doppler (TCD) and electroencephalography (EEG) in patients with vertebrobasilar insufficiency

BACKGROUND

To evaluate the diagnostic value of transcranial Doppler (TCD) and electroencephalography (EEG) in patients with vertebrobasilar insufficiency (VBI) during clinical diagnosis and treatment METHODS: Eighty patients diagnosed with VBI in our hospital from June 2018 to December 2019 were randomly selected as the observation group, and 80 healthy people who received physical examination in the same period were selected as the control group. The abnormal rate, main performance and results, and the peak velocity of blood flow and vertebrobasilar artery blood flow of the two groups were compared.

RESULTS

The abnormal rate of EEG and TCD in VBI patients was 38.75% (31/80) and the 93.75% (75/80), respectively. In TCD examination, ACA, PCA, MCA, and VA of both sides of the observation group were higher than those of the control group, while BA was lower than that of the control group (P < 0.05). The Vs, Vd, and Vm on both sides of BA and VA in the observation group were lower than those in the control group, while PI and RI were higher than those in the control group (P < 0.05).

CONCLUSIONS

TCD examination is highly sensitive to the degree and pattern of cerebral ischemia in VBI patients. EEG examination will define the changes of brain cell function after cerebral ischemia. Therefore, EEG and TCD have their own advantages. The application of TCD and EEG can be considered in the early diagnosis, curative effect, and prognosis evaluation of VBI patients, so as to improve the accuracy of diagnosis and prognosis.

Evaluation of the Uncertainty of Passive Cavitation Measurements for Blood-Brain Barrier Disruption Monitoring

Exposure to ultrasound combined with intravenous injection of microbubbles is a technique that can be used to temporarily disrupt the blood-brain barrier. Transcranial monitoring of cavitation can be done with one or more passive cavitation detectors (PCDs). However, the positioning of the PCDs relative to the cavitation site and the attenuation of these signals by the skull are two sources of error in the quantification of cavitation activity. The aim of this study was to evaluate in vitro the amplitude variation of cavitation signals that can be expected for an excised porcine skull model. The variation caused by the relative positioning of the PCD with respect to the cavitation site was quantified. A position-based correction of the signal amplitude was evaluated. Pig skull samples were used to assess variation in signal amplitude caused by bone. The overall coefficient of variation of the signals owing to these measurement biases was estimated at 30.8%.

Dynamic brain-body coupling of breath-by-breath O2-CO2 exchange ratio with resting state cerebral hemodynamic fluctuations

BACKGROUND

The origin of low frequency cerebral hemodynamic fluctuations (CHF) in the resting state remains unknown. Breath-by breath O2-CO2 exchange ratio (bER) has been reported to correlate with the cerebrovascular response to brief breath hold challenge at the frequency range of 0.008-0.03Hz in healthy adults. bER is defined as the ratio of the change in the partial pressure of oxygen (ΔPO2) to that of carbon dioxide (ΔPCO2) between end inspiration and end expiration. In this study, we aimed to investigate the contribution of respiratory gas exchange (RGE) metrics (bER, ΔPO2 and ΔPCO2) to low frequency CHF during spontaneous breathing.

METHODS

Twenty-two healthy adults were included. We used transcranial Doppler sonography to evaluate CHF by measuring the changes in cerebral blood flow velocity (ΔCBFv) in bilateral middle cerebral arteries. The regional CHF were mapped with blood oxygenation level dependent (ΔBOLD) signal changes using functional magnetic resonance imaging. Temporal features and frequency characteristics of RGE metrics during spontaneous breathing were examined, and the simultaneous measurements of RGE metrics and CHF (ΔCBFv and ΔBOLD) were studied for their correlation.

RESULTS

We found that the time courses of ΔPO2 and ΔPCO2 were interdependent but not redundant. The oscillations of RGE metrics were coherent with resting state CHF at the frequency range of 0.008-0.03Hz. Both bER and ΔPO2 were superior to ΔPCO2 in association with CHF while CHF could correlate more strongly with bER than with ΔPO2 in some brain regions. Brain regions with the strongest coupling between bER and ΔBOLD overlapped with many areas of default mode network including precuneus and posterior cingulate.

CONCLUSION

Although the physiological mechanisms underlying the strong correlation between bER and CHF are unclear, our findings suggest the contribution of bER to low frequency resting state CHF, providing a novel insight of brain-body interaction via CHF and oscillations of RGE metrics.

Localized Disruption of Blood Albumin-Phenytoin Binding Using Transcranial Focused Ultrasound

Plasma protein binding (PPB) plays an important role in drug pharmacokinetics, particularly for central nervous system drugs, as PPB affects the blood concentration of unbound drug available to cross the blood-brain barrier (BBB). We report the non-invasive, spatially specific disruption of PPB to phenytoin, an anti-epileptic drug with high affinity to albumin, using 250-kHz focused ultrasound (FUS) delivered in a pulsed manner (55-ms tone burst duration, 4-Hz pulse repetitions). Equilibrium dialysis performed on sonicated phosphate-buffered saline solution containing phenytoin and bovine serum albumin revealed a 27.7% elevation in the unbound phenytoin concentration compared with an unsonicated control. Sonication of a unilateral brain hemisphere in rats (n = 10) after intraperitoneal phenytoin injection revealed increased parenchymal phenytoin uptake compared with the unsonicated hemisphere, without evidence of temperature change or BBB disruption. These findings illustrate the use of FUS as a novel technique for spatially selective disruption of PPB, which may be applied to a wide range of drug-plasma protein interactions.

A Spectral Approach to Model-Based Noninvasive Intracranial Pressure Estimation

BACKGROUND

Intracranial pressure (ICP) normally ranges from 5 to 15 mmHg. Elevation in ICP is an important clinical indicator of neurological injury, and ICP is therefore monitored routinely in several neurological conditions to guide diagnosis and treatment decisions. Current measurement modalities for ICP monitoring are highly invasive, largely limiting the measurement to critically ill patients. An accurate noninvasive method to estimate ICP would dramatically expand the pool of patients that could benefit from this cranial vital sign.

METHODS

This article presents a spectral approach to model-based ICP estimation from arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV) measurements. The model captures the relationship between the ABP, CBFV, and ICP waveforms and utilizes a second-order model of the cerebral vasculature to estimate ICP.

RESULTS

The estimation approach was validated on two separate clinical datasets, one recorded from thirteen pediatric patients with a total duration of around seven hours, and the other recorded from five adult patients, one hour and 48 minutes in total duration. The algorithm was shown to have an accuracy (mean error) of 0.4 mmHg and -1.5 mmHg, and a precision (standard deviation of the error) of 5.1 mmHg and 4.3 mmHg, in estimating mean ICP (range of 1.3 mmHg to 24.8 mmHg) on the pediatric and adult data, respectively. These results are comparable to previous results and within the clinically relevant range. Additionally, the accuracy and precision in estimating the pulse pressure of ICP on a beat-by-beat basis were found to be 1.3 mmHg and 2.9 mmHg respectively.

CONCLUSION

These contributions take a step towards realizing the goal of implementing a real-time noninvasive ICP estimation modality in a clinical setting, to enable accurate clinical-decision making while overcoming the drawbacks of the invasive ICP modalities.

Does depth of squat-stand maneuver affect estimates of dynamic cerebral autoregulation?

Repeated squat-stand maneuvers (SSM) are an effective way of measuring dynamic cerebral autoregulation (dCA), but the depth of SSM required to improve dCA estimations has never been studied. We compared beat-to-beat cerebral hemodynamic parameters between maximal depth SSM (SSMD ) and a shallower alternative (SSMS ) in two age groups (younger [20-34 years] vs. older [50-71 years]) at a frequency of 0.05 Hz. Cerebral blood flow velocity, continuous blood pressure (BP) and end-tidal CO2 (EtCO2 ) were measured using transcranial Doppler ultrasound, the Finometer device, and capnography, respectively. Coherence (at 0.05 Hz) was significantly higher in both SSM recordings compared to spontaneous BP oscillations at baseline standing (BS ). Median (IQR) autoregulation index (ARI) was reduced during SSMD (4.46 [4.03-5.22], p < .01) compared to SSMS (5.96 [5.40-6.69]) and BS (6.03 [5.20-6.49], p < .01) with similar relative differences also observed for phase (at 0.05 Hz). End-tidal CO2 was increased in SSMD (38.3 ± 3.7 mmHg, p < .01) compared to both SSMS (36.6 ± 3.6 mmHg) and BS (35.5 ± 3.2 mmHg). The older group demonstrated significantly lower ARI and phase estimates during SSM and found SSMS more effortful than SSMD . In conclusion, both SSMD and SSMS are effective at estimating dCA, and dCA appears to be less efficient during maximal depth SSM compared to baseline rest or a shallower alternative.

A systematic review of ultrasound imaging and therapy in mental disorders

BACKGROUND

Increasing evidence suggests that ultrasound (US) imaging may provide biomarkers and therapeutic options in mental disorders. We systematically reviewed the literature to provide a global overview of the possibilities of US for psychiatry.

METHODS

Original English language articles published between January 2000 and September 2019 were identified through databases searching and analyzed to summarize existing evidence according to PRISMA methodology.

RESULTS

A total of 81 articles were included. Various US techniques and markers have been used in mental disorders, including Transcranial Doppler and Intima-Media Thickness. Most of the studies have focused on characterizing the pathophysiology of mental disorders, especially vascular physiology. Studies on therapeutic applications are still scarce.

DISCUSSION

US imaging has proved to be useful in characterizing vascular impairment and structural and functional brain changes in mental disorders. Preliminary findings also suggest potential interests for therapeutic applications. Growing evidence suggests that US imaging could provide a non-invasive, portable and low-cost tool for pathophysiological characterization, prognostic assessment and therapeutic applications in mental disorders.

Effects of 2D-Shear Wave Elastography on Brain-Derived Neurotrophic Factor (BDNF) in the Brains of Neonatal Mice and Exploration of the Mechanism

BACKGROUND The aim of this study was to explore the effect and duration of 2-dimensional shear wave elastography (2D-SWE) irradiation on the expression of brain-derived neurotrophic factor (BDNF) in the brains of neonatal mice and to preliminarily investigate whether its mechanism is neuronal apoptosis. MATERIAL AND METHODS Neonatal mice (within 48 hours of birth) were subjected to 2D-SWE irradiation of the brain for 10 minutes (group S1), 20 minutes (group S2), and 30 minutes (group S3). The mice were sacrificed immediately after irradiation or 24 hours after irradiation. Brains were collected for real-time polymerase chain reaction (RT-PCR) and western blot experiments to determine the expression of BDNF in each group. TdT-mediated dUTP nick-end labeling (TUNEL) was performed to observe neuronal apoptosis in the brain. RESULTS The results of PCR and western blots from the brains of neonatal mice that were sacrificed immediately after irradiation show that S1, S2, and S3 were significantly different from those in the control group. The PCR and western blot results of brain tissues from neonatal mice sacrificed at 24 hours after irradiation showed that there was no significant difference between the S1, S2, S3, and control groups. The results of TUNEL experiments showed that there was no statistically significant difference in the number of apoptotic neurons between the S1, S2, S3, and control groups. CONCLUSIONS 2D-SWE irradiation of neonatal mice for more than 10 minutes downregulated the expression of BDNF. This effect disappeared within 24 hours after the irradiation, and the 2D-SWE scan seemed not to induce neuronal apoptosis.

Multimodal non-invasive assessment of intracranial hypertension: an observational study

BACKGROUND

Although placement of an intra-cerebral catheter remains the gold standard method for measuring intracranial pressure (ICP), several non-invasive techniques can provide useful estimates. The aim of this study was to compare the accuracy of four non-invasive methods to assess intracranial hypertension.

METHODS

We reviewed prospectively collected data on adult intensive care unit (ICU) patients with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), or intracerebral hemorrhage (ICH) in whom invasive ICP monitoring had been initiated and estimates had been simultaneously collected from the following non-invasive indices: optic nerve sheath diameter (ONSD), pulsatility index (PI), estimated ICP (eICP) using transcranial Doppler, and the neurological pupil index (NPI) measured using automated pupillometry. Intracranial hypertension was defined as an invasively measured ICP > 20 mmHg.

RESULTS

We studied 100 patients (TBI = 30; SAH = 47; ICH = 23) with a median age of 52 years. The median invasively measured ICP was 17 [12-25] mmHg and intracranial hypertension was present in 37 patients. Median values from the non-invasive techniques were ONSD 5.2 [4.8-5.8] mm, PI 1.1 [0.9-1.4], eICP 21 [14-29] mmHg, and NPI 4.2 [3.8-4.6]. There was a significant correlation between all the non-invasive techniques and invasive ICP (ONSD, r = 0.54; PI, r = 0.50; eICP, r = 0.61; NPI, r = - 0.41-p < 0.001 for all). The area under the curve (AUC) to estimate intracranial hypertension was 0.78 [CIs = 0.68-0.88] for ONSD, 0.85 [95% CIs 0.77-0.93] for PI, 0.86 [95% CIs 0.77-0.93] for eICP, and 0.71 [95% CIs 0.60-0.82] for NPI. When the various techniques were combined, the highest AUC (0.91 [0.84-0.97]) was obtained with the combination of ONSD with eICP.

CONCLUSIONS

Non-invasive techniques are correlated with ICP and have an acceptable accuracy to estimate intracranial hypertension. The multimodal combination of ONSD and eICP may increase the accuracy to estimate the occurrence of intracranial hypertension.

Review: pathophysiology of intracranial hypertension and noninvasive intracranial pressure monitoring

Measurement of intracranial pressure (ICP) is crucial in the management of many neurological conditions. However, due to the invasiveness, high cost, and required expertise of available ICP monitoring techniques, many patients who could benefit from ICP monitoring do not receive it. As a result, there has been a substantial effort to explore and develop novel noninvasive ICP monitoring techniques to improve the overall clinical care of patients who may be suffering from ICP disorders. This review attempts to summarize the general pathophysiology of ICP, discuss the importance and current state of ICP monitoring, and describe the many methods that have been proposed for noninvasive ICP monitoring. These noninvasive methods can be broken down into four major categories: fluid dynamic, otic, ophthalmic, and electrophysiologic. Each category is discussed in detail along with its associated techniques and their advantages, disadvantages, and reported accuracy. A particular emphasis in this review will be dedicated to methods based on the use of transcranial Doppler ultrasound. At present, it appears that the available noninvasive methods are either not sufficiently accurate, reliable, or robust enough for widespread clinical adoption or require additional independent validation. However, several methods appear promising and through additional study and clinical validation, could eventually make their way into clinical practice.

Comparable blood velocity changes in middle and posterior cerebral arteries during and following acute high-intensity exercise in young fit women

The cerebral blood flow response to high-intensity interval training (HIIT) remains unclear. HIIT induces surges in mean arterial pressure (MAP), which could be transmitted to the brain, especially early after exercise onset. The aim of this study was to describe regional cerebral blood velocity changes during and following 30 s of high-intensity exercise. Ten women (age: 27 ± 6 years; VO2max : 48.6 ± 3.8 ml·kg·min-1 ) cycled for 30 s at the workload reached at V ˙ O2max followed by 3min of passive recovery. Middle (MCAvmean ) and posterior cerebral artery mean blood velocities (PCAvmean ; transcranial Doppler ultrasound), MAP (finger photoplethysmography), and end-tidal carbon dioxide partial pressure (PET CO2 ; gaz analyzer) were measured. MCAvmean (+19 ± 10%) and PCAvmean (+21 ± 14%) increased early after exercise onset, returning toward baseline values afterward. MAP increased throughout exercise (p < .0001). PET CO2 initially decreased by 3 ± 2 mmHg (p < .0001) before returning to baseline values at end-exercise. During recovery, MCAvmean (+43 ± 15%), PCAvmean (+42 ± 15%), and PET CO2 (+11 ± 3 mmHg; p < .0001) increased. In young fit women, cerebral blood velocity quickly increases at the onset of a 30-s exercise performed at maximal workload, before returning to baseline values through the end of the exercise. During recovery, cerebral blood velocity augments in both arteries, along with PET CO2 .

Acoustic biomolecules enhance hemodynamic functional ultrasound imaging of neural activity

Hemodynamic functional ultrasound imaging (fUS) of neural activity provides a unique combination of spatial coverage, spatiotemporal resolution and compatibility with freely moving animals. However, deep and transcranial monitoring of brain activity and the imaging of dynamics in slow-flowing blood vessels remains challenging. To enhance fUS capabilities, we introduce biomolecular hemodynamic enhancers based on gas vesicles (GVs), genetically encodable ultrasound contrast agents derived from buoyant photosynthetic microorganisms. We show that intravenously infused GVs enhance ultrafast Doppler ultrasound contrast and visually-evoked hemodynamic contrast in transcranial fUS of the mouse brain. This hemodynamic contrast enhancement is smoother than that provided by conventional microbubbles, allowing GVs to more reliably amplify neuroimaging signals.

Essential Noninvasive Multimodality Neuromonitoring for the Critically Ill Patient

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2020. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2020. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Transcranial Doppler Sonography Defined Vasospasm, Ischemic Brain Lesions, and Delayed Ischemic Neurological Deficit in Younger and Elderly Patients after Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Vasospasm, delayed ischemic neurologic deficit (DIND), and ischemic brain lesions after acute subarachnoid hemorrhage (SAH) are associated with increased morbidity and mortality. The purpose of this study was to analyze age cutoffs for vasospasm, DIND, and ischemic brain lesions after SAH.

METHODS

This study included 292 aneurysmal SAH patients from January 2005 to December 2015. Patients' data were extracted from a prospective database with measurements of transcranial Doppler sonography. Any vasospasm was defined as a maximum mean flow velocity (MMFV) >120 cm/sec. Severe vasospasms were defined as at least 2 measurements of MMFVs >200 cm/sec or an increase of MMFV >50 cm/sec/24 hours over 2 consecutive days or a new neurologic deficit. All MMFVs >120 cm/sec in absence of severe vasospasm criteria were defined as mild vasospasm. Age-related cutoff values were calculated using receiver operating curve analysis.

RESULTS

Any vasospasms occurred in 142 patients and thereof mild vasospasm in 86/142 (60.6%) patients and severe vasospasm in 56/142 patients (39.4%). Significantly higher incidences of any vasospasm (P = 0.005), severe vasospasm (P = 0.003), DIND (P = 0.031), and ischemic brain lesions (P = 0.04) were observed in patients aged <50 years. According to receiver operating curve analysis, the optimal age cutoff was 50 years for the presence of overall vasospasms, severe vasospasms, DIND, and ischemic brain lesions and 65 years for mild vasospasms.

CONCLUSIONS

Higher incidences of any vasospasms, severe vasospasms, DIND, and ischemic brain lesions were observed in younger SAH patients.

Advances in Sonothrombolysis Techniques Using Piezoelectric Transducers

One of the great advancements in the applications of piezoelectric materials is the application for therapeutic medical ultrasound for sonothrombolysis. Sonothrombolysis is a promising ultrasound based technique to treat blood clots compared to conventional thrombolytic treatments or mechanical thrombectomy. Recent clinical trials using transcranial Doppler ultrasound, microbubble mediated sonothrombolysis, and catheter directed sonothrombolysis have shown promise. However, these conventional sonothrombolysis techniques still pose clinical safety limitations, preventing their application for standard of care. Recent advances in sonothrombolysis techniques including targeted and drug loaded microbubbles, phase change nanodroplets, high intensity focused ultrasound, histotripsy, and improved intravascular transducers, address some of the limitations of conventional sonothrombolysis treatments. Here, we review the strengths and limitations of these latest pre-clincial advancements for sonothrombolysis and their potential to improve clinical blood clot treatments.

Transcranial Doppler sonography for detecting stenosis or occlusion of intracranial arteries in people with acute ischaemic stroke

BACKGROUND

An occlusion or stenosis of intracranial large arteries can be detected in the acute phase of ischaemic stroke in about 42% of patients. The approved therapies for acute ischaemic stroke are thrombolysis with intravenous recombinant tissue plasminogen activator (rt-PA), and mechanical thrombectomy; both aim to recanalise an occluded intracranial artery. The reference standard for the diagnosis of intracranial stenosis and occlusion is intra-arterial angiography (IA) and, recently, computed tomography angiography (CTA) and magnetic resonance angiography (MRA), or contrast-enhanced MRA. Transcranial Doppler (TCD) and transcranial colour Doppler (TCCD) are useful, rapid, noninvasive tools for the assessment of intracranial large arteries pathology. Due to the current lack of consensus regarding the use of TCD and TCCD in clinical practice, we systematically reviewed the literature for studies assessing the diagnostic accuracy of these techniques compared with intra-arterial IA, CTA, and MRA for the detection of intracranial stenosis and occlusion in people presenting with symptoms of ischaemic stroke.

OBJECTIVES

To assess the diagnostic accuracy of TCD and TCCD for detecting stenosis and occlusion of intracranial large arteries in people with acute ischaemic stroke.

SEARCH METHODS

We limited our searches from January 1982 onwards as the transcranial Doppler technique was only introduced into clinical practice in the 1980s. We searched MEDLINE (Ovid) (from 1982 to 2018); Embase (Ovid) (from 1982 to 2018); Database of Abstracts of Reviews of Effects (DARE); and Health Technology Assessment Database (HTA) (from 1982 to 2018). Moreover, we perused the reference lists of all retrieved articles and of previously published relevant review articles, handsearched relevant conference proceedings, searched relevant websites, and contacted experts in the field.

SELECTION CRITERIA

We included all studies comparing TCD or TCCD (index tests) with IA, CTA, MRA, or contrast-enhanced MRA (reference standards) in people with acute ischaemic stroke, where all participants underwent both the index test and the reference standard within 24 hours of symptom onset. We included prospective cohort studies and randomised studies of test comparisons. We also considered retrospective studies eligible for inclusion where the original population sample was recruited prospectively but the results were analysed retrospectively.

DATA COLLECTION AND ANALYSIS

At least two review authors independently screened the titles and abstracts identified by the search strategies, applied the inclusion criteria, extracted data, assessed methodological quality (using QUADAS-2), and investigated heterogeneity. We contacted study authors for missing data.

MAIN RESULTS

A comprehensive search of major relevant electronic databases (MEDLINE and Embase) from 1982 to 13 March 2018 yielded 13,534 articles, of which nine were deemed eligible for inclusion. The studies included a total of 493 participants. The mean age of included participants was 64.2 years (range 55.8 to 69.9 years). The proportion of men and women was similar across studies. Six studies recruited participants in Europe, one in south America, one in China, and one in Egypt. Risk of bias was high for participant selection but low for flow, timing, index and reference standard. The summary sensitivity and specificity estimates for TCD and TCCD were 95% (95% CI = 0.83 to 0.99) and 95% (95% CI = 0.90 to 0.98), respectively. Considering a prevalence of stenosis or occlusion of 42% (as reported in the literature), for every 1000 people who receive a TCD or TCCD test, stenosis or occlusion will be missed in 21 people (95% CI = 4 to 71) and 29 (95% CI = 12 to 58) will be wrongly diagnosed as harbouring an intracranial occlusion. However, there was substantial heterogeneity between studies, which was no longer evident when only occlusion of the MCA was considered, or when the analysis was limited to participants investigated within six hours. The performance of either TCD or TCCD in ruling in and ruling out a MCA occlusion was good. Limitations of this review were the small number of identified studies and the lack of data on the use of ultrasound contrast medium.

AUTHORS' CONCLUSIONS

This review provides evidence that TCD or TCCD, administered by professionals with adequate experience and skills, can provide useful diagnostic information for detecting stenosis or occlusion of intracranial vessels in people with acute ischaemic stroke, or guide the request for more invasive vascular neuroimaging, especially where CT or MR-based vascular imaging are not immediately available. More studies are needed to confirm or refute the results of this review in a larger sample of stroke patients, to verify the role of contrast medium and to evaluate the clinical advantage of the use of ultrasound.

Analyzing the co-localization of substantia nigra hyper-echogenicities and iron accumulation in Parkinson's disease: A multi-modal atlas study with transcranial ultrasound and MRI

•

Volumetric 3D analysis of hyper-echogenicities from transcranial ultrasound (TCS).

•

First multi-modal analysis of TCS and QSM-MRI in Parkinson's disease.

•

Computations of TCS-MRI registration and a novel multi-modal anatomical template.

•

TCS hyper-echogenicities are co-localized with QSM iron accumulations.

•

Co-localizations occur in the SNc and VTA, but nowhere else in the midbrain.

Background

Transcranial B-mode sonography (TCS) can detect hyperechogenic speckles in the area of the substantia nigra (SN) in Parkinson's disease (PD). These speckles correlate with iron accumulation in the SN tissue, but an exact volumetric localization in and around the SN is still unknown. Areas of increased iron content in brain tissue can be detected in vivo with magnetic resonance imaging, using quantitative susceptibility mapping (QSM).

Methods

In this work, we i) acquire, co-register and transform TCS and QSM imaging from a cohort of 23 PD patients and 27 healthy control subjects into a normalized atlas template space and ii) analyze and compare the 3D spatial distributions of iron accumulation in the midbrain, as detected by a signal increase (TCS+ and QSM+) in both modalities.

Results

We achieved sufficiently accurate intra-modal target registration errors (TRE<1 mm) for all MRI volumes and multi-modal TCS-MRI co-localization (TRE<4 mm) for 66.7% of TCS scans. In the caudal part of the midbrain, enlarged TCS+ and QSM+ areas were located within the SN pars compacta in PD patients in comparison to healthy controls. More cranially, overlapping TCS+ and QSM+ areas in PD subjects were found in the area of the ventral tegmental area (VTA).

Conclusion

Our findings are concordant with several QSM-based studies on iron-related alterations in the area SN pars compacta. They substantiate that TCS+ is an indicator of iron accumulation in Parkinson's disease within and in the vicinity of the SN. Furthermore, they are in favor of an involvement of the VTA and thereby the mesolimbic system in Parkinson's disease.

Transcranial color-coded sonography may indirectly reveal an intracranial meningioma

Meningiomas are extra-axial tumors with a long-standing indolent clinical course. Sphenoid wing meningiomas may slowly grow, spreading toward the orbitofrontal and temporal regions as well as encasing the middle cerebral artery (MCA). Herein, we report the incidental finding of a sphenoid wing meningioma compressing the MCA in a patient who undergone a transcranial sonography study for recurrent speech disorders. We illustrate the associated sonographic "red flags" which should prompt to suspect an underlying compressive space-occupying lesion.

Magnetic resonance angiography and transcranial Doppler ultrasound findings in patients with a clinical diagnosis of vertebrobasilar insufficiency

OBJECTIVE

To evaluate the findings of magnetic resonance angiography (MRA) and transcranial Doppler ultrasound (TCD) in patients with a clinical diagnosis of vertebrobasilar insufficiency (VBI).

METHOD

From our outpatient neurotology clinic, we selected patients (using the criteria proposed by Grad and Baloh) with a clinical diagnosis of VBI. We excluded patients with any definite cause for vestibular symptoms, a noncontrolled metabolic disease or any contraindication to MRA or TCD. The patients in the study group were sex- and age-matched with subjects who did not have vestibular symptoms (control group). Our final group of patients included 24 patients (study, n=12; control, n=12).

RESULTS

The MRA results did not demonstrate significant differences in the findings between our study and control groups. TCD demonstrated that the systolic pulse velocity of the right middle cerebral artery, end diastolic velocity of the basilar artery, pulsatility index (PI) of the left middle cerebral artery, PI of the right middle cerebral artery, and PI of the basilar artery were significantly higher in the study group than in the control group, suggesting abnormalities affecting the microcirculation of patients with a clinical diagnosis of VBI compared with controls.

CONCLUSION

MRA failed to reveal abnormalities in patients with a clinical diagnosis of VBI compared with controls. The PI of the basilar artery, measured using TCD, demonstrated high sensitivity (91%) and specificity (91%) for detecting clinically diagnosed VBI.

Impact of contrast-enhanced transcranial Doppler ultrasound diagnosis for young adult with cryptogenic stroke: A protocol of systematic review

BACKGROUND

This study aims to assess the impact of contrast-enhanced transcranial Doppler ultrasound (cTCD) diagnosis for young adult with cryptogenic stroke (CS).

METHODS

This study will analyze data from case-controlled studies investigating the impact of cTCD diagnosis for young adult with CS. A comprehensive literature search will be performed from PUBMED, EMBASE, Cochrane Library, Web of Science, Cumulative Index to Nursing and Allied Health Literature, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, and Wanfang Data from their inceptions up to the August 1, 2019. All databases will be searched with no language limitations. Two researchers will independently carry out study selection, data collection, and study quality assessment. Any discrepancies between two researchers will be solved by a third researcher. We will apply RevMan 5.3 software and Stata 12.0 software for statistical analysis.

RESULTS

Outcomes consist of sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio for determination of cTCD diagnosis for young adult with CS.

CONCLUSION

The results of this study may summarize up-to-date evidence of cTCD diagnosis for young adult with CS.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42019145641.

Cerebrovascular Pulsatility During Rest and Exercise Reflects Hemodynamic Impairment in Stroke and Cerebral Small Vessel Disease

Although aerobic exercise is recommended as a core component of stroke rehabilitation, knowledge of acute cerebrovascular responses in patients is limited. This study tested the hypothesis that older adults with chronic stroke or cerebral small vessel disease (SVD) exhibit a greater increase in pulsatile hemodynamics during exercise compared with young and age-matched healthy adults. Middle cerebral artery blood flow velocity was acquired during 20 min of moderate intensity cycling in 51 participants from four groups (young, old, SVD and stroke). During rest, only the stroke group had a higher pulsatility index (PI) compared with the young group (1.02 ± 0.17 vs 0.83 ± 0.13; p = 0.038). During exercise, however, the SVD group exhibited a larger increase in PI (68 ± 20% relative to rest) than the young (47 ± 19%), old (45 ± 17%) and stroke (40 ± 25%) groups (p < 0.05, for each). The stress of aerobic exercise may reveal arterial dysfunction associated with latent and overt cerebrovascular disease.

Young male with syphilitic cerebral arteritis presents with signs of acute progressive stroke: A case report

INTRODUCTION

Neurosyphilis is a chronic infection of the central nervous system that is commonly found in adult with long latency periods. Neurosyphilis-attributed deaths in young patients have grown exponentially in the past decade, yet there have been few studies on the early stages of neurosyphilis.

PATIENT CONCERNS

A young male patient with syphilitic cerebral arteritis was evaluated in our clinic for the clinical signs of progressive ischemic stroke.

DIAGNOSIS

The progression of syphilitic cerebral arteritis was observed through computed tomography imaging, magnetic resonance imaging, magnetic resonance angiogram, and transcranial color Doppler. The pathological changes and clinical outcomes were reviewed. In this specific case, the development of syphilitic cerebral arteritis was dynamic, continuous, and rapid. The pathogenesis was related to Heubner arteritis, in which the formation of a mural thrombus (MT) causes the severe obstruction of blood flow without complete occlusion, leading to an increased risk of infarction. In this patient, formation of the MT resulted in the infarction of the smaller vessels and narrowing of the larger vessels. The partial dislodgment of the MT from the arterial wall of the larger vessels occluded the smaller vessels, leading to infarction.

INTERVENTIONS

Standard pharmacotherapy for the treatment of the cerebral infarction and a single course of penicillin were applied.

OUTCOMES

Muscle strength was recovered. The Glasgow Coma Scale score was 15, whereas the NIH Stroke Scale score was 0. The increase in blood flow of the right MCA was accompanied by severe stenosis with compensation of the anterior communicating artery. In addition, moderate to severe stenosis of the right vertebral artery and the basilar artery was suspected. There was a possibility that the right posterior communicating artery was recruited for compensation.

CONCLUSION

Progressive stroke was the initial symptom of the neurosyphilis. Disease progression is rapid and difficult to control with a single course of penicillin.

Perfusion Enhancement with Respiratory Impedance After Stroke (PERI-Stroke)

Intrathoracic pressure influences cardiac output and may affect cerebral blood flow (CBF). We aimed to quantify the cerebral hemodynamic response to intrathoracic pressure reduction in patients with acute ischemic stroke using a noninvasive respiratory impedance (RI) device. We assessed low-level (6 cm H2O) and high-level (12 cm H2O) RI in 17 spontaneously breathing patients within 72 h of anterior circulation acute ischemic stroke. Average age was 65 years, and 35% were female. Frontal lobe tissue perfusion and middle cerebral artery velocity (MCAv) were continuously monitored with optical diffuse correlation spectroscopy (DCS) and transcranial Doppler ultrasound, respectively. High-level RI resulted in a 7% increase in MCAv (p = 0.004). MCAv varied across all studied levels (baseline vs low-level vs high-level, p = 0.006), with a significant test of trend (p = 0.002). Changes were not seen in DCS measured tissue perfusion by nonparametric pairwise comparison. Mixed effects regression analysis identified a small increase in both MCAv (low-level RI: β 2.1, p < 0.001; high-level RI: β 5.0, p < 0.001) and tissue-level flow (low-level RI: β 5.4, p < 0.001; high-level RI: β 5.9, p < 0.001). There was a small increase in mean arterial pressure during low-level and high-level RI, 4% (p = 0.013) and 4% (p = 0.017), respectively. End-tidal CO2 remained stable throughout the protocol. RI was well tolerated. Manipulating intrathoracic pressure via noninvasive RI was safe and produced a small but measurable increase in cerebral perfusion in acute ischemic stroke patients. Future studies are warranted to assess whether RI is feasible and tolerable for prolonged use in hyperacute stroke management.

Transcranial Color-Coded Sonography for the Detection of Cerebral Veins and Sinuses and Diagnosis of Cerebral Venous Sinus Thrombosis

This study aimed to determine the detection rate of transcranial color-coded sonography (TCCS) of cerebral veins and sinuses and to explore the diagnostic accuracy of TCCS for straight sinus (SS) and transverse sinus (TS) thromboses. The detection rates of cerebral veins and sinuses using TCCS and contrast-enhanced TCCS (CE-TCCS) were analyzed. The diagnostic accuracy of CE-TCCS was evaluated. Median time from symptoms to CE-TCCS was 10 (range, 1-150) d. The detection rate of bilateral basal veins of Rosenthal was 100% by CE-TCCS, followed by right TS (91.89%), SS (88.12%), left TS (74.59%) and vein of Galen (70.27%). Compared with magnetic resonance imaging/magnetic resonance venography, CE-TCCS showed 100% sensitivity and 96.3% specificity for SS thrombosis, 100% and 100% for right TS thrombosis and 100% and 94.4% for left TS thrombosis. In conclusion, CE-TCCS shows high identification rates of cerebral veins and sinuses and a high diagnostic accuracy for SS and TS thrombosis.

Multiple Kernel Learning Based Classification of Parkinson's Disease With Multi-Modal Transcranial Sonography

Parkinson's Disease (PD) is the most common motor neurodegenerative disease in elderly population. Transcranial sonography (TCS) has become a popular imaging tool for diagnosis of PD in clinical practice. Moreover, several pioneering work have developed the computer-aided diagnosis (CAD) for PD with the transcranial B-mode sonography (TBS). It is worth noting that TCS not only has the TBS modality, but also can image the blood flow of major cerebral arteries, which is named transcranial Doppler sonography (TDS). TDS also has been applied to evaluate PD patients with orthostatic hypotension. However, the TDS-based CAD for PD has not been investigated. Since TBS and TDS provide the complementary structural and functional information about brain, it is feasible to develop a multi-modal TCS-based CAD for PD by combining both TBS and TDS. Therefore, in this work, we propose a multiple kernel learning (MKL) based CAD for PD with multi-modal TCS imaging. Particularly, the statistical and texture features are extracted from the midbrain region from TBS images, and the features about blood flow are calculated from the spectrum curves in TDS. The multi-modal features are then fed to a MKL classifier for classification of PD. The experimental results show that the multi-modal TCS-based method outperforms both the single-modal TBS- and TDS-based algorithm, which suggests the feasibility and effectiveness of combining TBS and TDS for diagnosis of PD.

Use of a Doppler-Based Pulsatility Index to Evaluate Cerebral Hemodynamics in Neurocritical Patients After Hemicraniectomy

OBJECTIVES

As a noninvasive method for evaluation of cerebral hemodynamics, the correct interpretation of transcranial Doppler or transcranial imaging (TCI) data remains a major challenge. We explored how to interpret the pulsatility index (PI) derived via TCI during evaluations of cerebral hemodynamics in posthemicraniectomy patients.

METHODS

We included patients who underwent invasive arterial pressure and intracranial pressure (ICP) monitoring and simultaneous TCI examinations after hemicraniectomy. We classified the PI of the middle cerebral artery (MCA) into ipsilateral (craniectomy side) and contralateral (opposite side) and analyzed both data sets. The statistical analysis was performed by the Bland-Altman approach, by calculating intraclass correlation coefficients and Spearman correlations, and by drawing receiver operating characteristic curves. Pulsatility index probability charts were created for ICPs exceeding 20, 25, and 30 mm Hg and cerebral perfusion pressures (CPPs) lower than 70, 60, and 50 mm Hg; we thus explored defined ICP and CPP values.

RESULTS

The ipsilateral and contralateral MCA PI data differed. Only the ipsilateral MCA PI showed a weak correlation with ICP (r = 0.378; P < .001). The receiver operating characteristic curve analysis revealed limited diagnostic utility of bilateral MCA PIs for ICP and CPP assessments. An extremely elevated MCA PI indicated that patients were at high risk of a dangerous ICP elevation or CPP reduction. However, MCA PI values within the normal range did not effectively rule out an ICP of 20 mm Hg or higher but effectively eliminated a CPP lower than 50 mm Hg.

CONCLUSIONS

In posthemicraniectomy patients, the Doppler-based MCA PI value was ineffectively for quantitative ICP and CPP evaluations but a useful index for assessment of cerebral hemodynamics in terms of the probability of an ICP elevation or a CPP reduction.

Cerebral Artery Vasospasm Detection Using Transcranial Doppler Signal Analysis

OBJECTIVES

Silent cerebral artery vasospasm in aneurysmal subarachnoid hemorrhage causes serious complications such as cerebral ischemia and death. A transcranial Doppler (TCD) ultrasound system is a noninvasive device that can effectively detect cerebral artery vasospasm as soon as it sets in, even before and in the absence of clinical deterioration. Continuous or even daily TCD monitoring is challenging because of the operator expertise and certification required in the form of a trained sonographer and interpretive experience required in the form of an additionally trained and certified physician to perform these studies. This barrier exists because of a lack of automation for detection (without human intervention) of cerebral artery vasospasm using TCD ultrasound. To overcome this barrier, we present an algorithm that automates detection of cerebral artery vasospasm.

METHODS

We extracted features such as the energy, energy entropy, zero-crossing rate, spectral centroid, spectral speed, spectral entropy, spectral flux, spectral roll-off, harmonic ratio, chroma, and Mel frequency cepstral coefficients for signal classification. Then we applied principal component analysis to reduce the data dimensionality.

RESULTS

All of the chosen features were used for training a decision-tree classifier. The algorithm had high accuracy for cerebral artery vasospasm detection, with overall sensitivity of 87.5% and specificity of 89.74%.

CONCLUSIONS

The algorithm has the potential for development into a continuous cerebral artery vasospasm monitor.

Associations of transcranial doppler velocity, age, and gender with cognitive function in children with sickle cell anemia in Nigeria

Children with sickle cell anemia (SCA) have elevated cerebral blood velocity relative to healthy peers. The primary aim of this study was to evaluate the association between cerebral blood velocity, measured by transcranial Doppler (TCD) ultrasound, age, and gender with cognitive function in children with SCA in Nigeria. Eighty-three children (Mage = 9.10, SD = 1.90 years; 55% female) with SCA in Nigeria completed cognitive assessments and a TCD ultrasound. The association between TCD velocity and measures of perceptual reasoning (Raven's Progressive Matrices), working memory (WISC-IV Digit Span), and executive planning (Tower of London, TOL) were assessed. Results showed that elevated TCD velocity significantly predicted lower scores on TOL Time Violations and Total Problem-Solving Time when controlling for BMI, hemoglobin level, and parent education, suggesting that TCD velocity is related to the efficiency of executive function. Further, age was negatively related to children's performance on the Ravens Matrices and TOL Total Correct, and boys showed greater deficits on the TOL Total Correct relative to girls. Moderation analyses for gender showed that there was a conditional negative association between TCD velocity and Digit Span for boys, but not for girls. Findings suggest that children with SCA in Nigeria with elevated TCD velocity are at risk for deficits in efficiency of executive planning, and boys with elevated TCD velocity are particularly at increased risk for deficits in auditory working memory. Implications of this study are important for interventions to reduce cerebral blood velocity and the use of TCD in this population.

Increased Sylvian fissure angle as early sonographic sign of malformation of cortical development

OBJECTIVE

To evaluate Sylvian fissure development by assessing Sylvian fissure angles in fetuses with malformation of cortical development (MCD).

METHODS

This was a retrospective study of 22 fetuses with MCD. Cases with a stored three-dimensional (3D) brain volume acquired at 18 + 0 to 30 + 6 weeks of gestation at an ultrasound-based research clinic between January 2010 and December 2017 were identified through a database. Of the 22 fetuses, seven had an extracranial abnormality, such as cardiac, renal, gastrointestinal and/or digital anomalies, and five had a minor abnormality such as micrognathia, low-set ears and/or single umbilical artery. To confirm the final clinical diagnosis of brain abnormality, postmortem histological findings or prenatal or postnatal magnetic resonance images were used. For measurement of Sylvian fissure angle, an anterior coronal plane of the fetal brain on transvaginal 3D volume multiplanar imaging was visualized as a single image from the three orthogonal views. The right and left Sylvian fissure angles were measured between a horizontal reference line (0°) and a line drawn along the upper side of the respective Sylvian fissure. The Sylvian fissure angle on both sides was plotted on the graphs of the reference ranges for gestational age in weeks.

RESULTS

In 21 (95.5%; 95% CI, 86.8-100.0%) of 22 fetuses with MCD, the Sylvian fissure angle on one or both sides was larger than the 90^th percentile of the normal reference. There was one case with apparent focal MCD in the parietal lobe, but the Sylvian fissure angles were normal. A case with apparent unilateral cortical dysplasia and one with apparent unilateral schizencephaly had conspicuous discrepancies between the left and right Sylvian fissure angles. Abnormal genetic test results were obtained in six cases, including four cases with a mutation in a single gene.

CONCLUSIONS

This study has shown that the Sylvian fissures, as defined by the Sylvian fissure angle, have delayed development in most MCD cases prior to the diagnosis of the condition. The Sylvian fissure angle may potentially be a strong indicator for the subsequent development of cortical malformation, before the time point at which the gyri and sulci become obvious on the fetal brain surface. Further research is required to validate these findings. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Responses of cerebral blood velocity and tissue oxygenation to low-frequency oscillations during simulated haemorrhagic stress in humans

NEW FINDINGS

What is the central question of this study? Do low-frequency oscillations in arterial pressure and cerebral blood velocity protect cerebral blood velocity and oxygenation during central hypovolaemia? What is the main finding and its importance? Low-frequency oscillations in arterial pressure and cerebral blood velocity attenuate reductions in cerebral oxygen saturation but do not protect absolute cerebral blood velocity during central hypovolaemia. This finding indicates the potential importance of haemodynamic oscillations in maintaining cerebral oxygenation and therefore viability of tissues during challenges to cerebral blood flow and oxygen delivery.

ABSTRACT

Tolerance to both real and simulated haemorrhage varies between individuals. Exaggerated low-frequency (∼0.1 Hz) oscillations in mean arterial pressure and brain blood flow [indexed via middle cerebral artery velocity (MCAv)] have been associated with improved tolerance to reduced central blood volume. The mechanism for this association has not been explored. We hypothesized that inducing low-frequency oscillations in arterial pressure and cerebral blood velocity would attenuate reductions in cerebral blood velocity and oxygenation during simulated haemorrhage. Fourteen subjects (11 men and three women) were exposed to oscillatory (0.1 and 0.05 Hz) and non-oscillatory (0 Hz) lower-body negative pressure profiles with an average chamber pressure of -60 mmHg (randomized and counterbalanced order). Measurements included arterial pressure and stroke volume via finger photoplethysmography, MCAv via transcranial Doppler ultrasound, and cerebral oxygenation of the frontal lobe via near-infrared spectroscopy. Tolerance was higher during the two oscillatory profiles compared with the 0 Hz profile (0.05 Hz, P = 0.04; 0.1 Hz, P = 0.09), accompanied by attenuated reductions in stroke volume (P < 0.001) and cerebral oxygenation of the frontal lobe (P ≤ 0.02). No differences were observed between profiles for reductions in mean arterial pressure (P = 0.17) and MCAv (P = 0.30). In partial support of our hypothesis, cerebral oxygenation, but not cerebral blood velocity, was protected during the oscillatory profiles. Interestingly, more subjects tolerated the oscillatory profiles compared with the static 0 Hz profile, despite similar arterial pressure responses. These findings emphasize the potential importance of haemodynamic oscillations in maintaining perfusion and oxygenation of cerebral tissues during haemorrhagic stress.

Diagnosis of elevated intracranial pressure in critically ill adults: systematic review and meta-analysis

OBJECTIVES

To summarise and compare the accuracy of physical examination, computed tomography (CT), sonography of the optic nerve sheath diameter (ONSD), and transcranial Doppler pulsatility index (TCD-PI) for the diagnosis of elevated intracranial pressure (ICP) in critically ill patients.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Six databases, including Medline, EMBASE, and PubMed, from inception to 1 September 2018.

STUDY SELECTION CRITERIA

English language studies investigating accuracy of physical examination, imaging, or non-invasive tests among critically ill patients. The reference standard was ICP of 20 mm Hg or more using invasive ICP monitoring, or intraoperative diagnosis of raised ICP.

DATA EXTRACTION

Two reviewers independently extracted data and assessed study quality using the quality assessment of diagnostic accuracy studies tool. Summary estimates were generated using a hierarchical summary receiver operating characteristic (ROC) model.

RESULTS

40 studies (n=5123) were included. Of physical examination signs, pooled sensitivity and specificity for increased ICP were 28.2% (95% confidence interval 16.0% to 44.8%) and 85.9% (74.9% to 92.5%) for pupillary dilation, respectively; 54.3% (36.6% to 71.0%) and 63.6% (46.5% to 77.8%) for posturing; and 75.8% (62.4% to 85.5%) and 39.9% (26.9% to 54.5%) for Glasgow coma scale of 8 or less. Among CT findings, sensitivity and specificity were 85.9% (58.0% to 96.4%) and 61.0% (29.1% to 85.6%) for compression of basal cisterns, respectively; 80.9% (64.3% to 90.9%) and 42.7% (24.0% to 63.7%) for any midline shift; and 20.7% (13.0% to 31.3%) and 89.2% (77.5% to 95.2%) for midline shift of at least 10 mm. The pooled area under the ROC (AUROC) curve for ONSD sonography was 0.94 (0.91 to 0.96). Patient level data from studies using TCD-PI showed poor performance for detecting raised ICP (AUROC for individual studies ranging from 0.55 to 0.72).

CONCLUSIONS

Absence of any one physical examination feature is not sufficient to rule out elevated ICP. Substantial midline shift could suggest elevated ICP, but the absence of shift cannot rule it out. ONSD sonography might have use, but further studies are needed. Suspicion of elevated ICP could necessitate treatment and transfer, regardless of individual non-invasive tests.

REGISTRATION

PROSPERO CRD42018105642.

Virtual Brain Projection for Evaluating Trans-skull Beam Behavior of Transcranial Ultrasound Devices

Focused ultrasound single-element piezoelectric transducers constitute a promising method to deliver ultrasound to the brain in low-intensity applications, but are subject to defocusing and high attenuation because of transmission through the skull. Here, a novel virtual brain projection method is used to superimpose a magnetic resonance image of the brain in ex vivo human skulls to provide targets during trans-skull focused ultrasound single-element piezoelectric transducer pressure field mapping. Positions of the transducer, skull and hydrophone are tracked in real time using a stereoscopic navigation camera and 3-D Slicer software. Virtual targets of the left dorsolateral prefrontal cortex, left hippocampus and cerebellar vermis were chosen to illustrate the method's flexibility in evaluating focal-zone beam distortion and attenuation. The regions are of interest as non-invasive brain stimulation targets in the treatment of neuropsychiatric disorders via repeated ultrasound exposure. The technical approach can facilitate the assessment of transcranial ultrasound device operator positioning reliability, intracranial beam behavior and computational model validation.

Systematic review with network meta-analysis: Diagnostic values of ultrasonography, computed tomography, and magnetic resonance imaging in patients with ischemic stroke

BACKGROUND AND OBJECTIVE

Ischemic stroke is a foremost cause for disability and death worldwide. This study is conducted in order to compare the diagnostic values between transcranial Doppler ultrasound (ultrasonography), computed tomography (CT), and magnetic resonance imaging (MRI) in patients suffering from ischemic stroke by performing a network meta-analysis.

METHODS

We made use of Cochrane Library, PubMed, and Embase in order to obtain literature and papers. The combination analysis of both direct and indirect evidence in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy was conducted so as to assess the odds ratios (ORs) and surface under the cumulative ranking curve (SUCRA) values of the seven different imaging methods. These imaging techniques include ultrasonography, computed tomography (traditional CT, computed tomography angiography [CTA], computed tomography perfusion [CTP]), and MRI (traditional MRI, diffusion-weighted imaging [DWI], magnetic resonance angiography), in order to properly diagnose ischemic stroke patients.

RESULTS

Thirteen eligible diagnostic trials were enrolled into this network meta-analysis. The results of the traditional meta-analysis showed that among CT methods, CTP showed higher sensitivity, NPV, and accuracy; among MRI methods, DWI had relatively higher sensitivity, NPV, and accuracy. The results of network meta-analysis showed that DWI had relatively higher sensitivity, NPV, and accuracy when compared with traditional CT, CTA, magnetic resonance angiography and traditional MRI. CTP showed higher SUCRA among CT methods while DWI showed higher SUCRA among MRI methods. A cluster analysis revealed that DWI had the highest diagnostic value in terms of sensitivity, PPV, NPV, and accuracy amongst the aforementioned seven imaging techniques.

CONCLUSION

This network meta-analysis provides supporting evidence to the idea that DWI has a higher diagnostic value regarding ischemic stroke among MRI methods, and CTP has a poor diagnostic value among CT methods, which provide therapeutic considerations for Ischemic stroke intervention.

Objective Assessment of Beat Quality in Transcranial Doppler Measurement of Blood Flow Velocity in Cerebral Arteries

OBJECTIVE

Transcranial Doppler (TCD) ultrasonography measures pulsatile cerebral blood flow velocity in the arteries and veins of the head and neck. Similar to other real-time measurement modalities, especially in healthcare, the identification of high-quality signals is essential for clinical interpretation. Our goal is to identify poor quality beats and remove them prior to further analysis of the TCD signal.

METHODS

We selected objective features for this purpose including Euclidean distance between individual and average beat waveforms, cross-correlation between individual and average beat waveforms, ratio of the high-frequency power to the total beat power, beat length, and variance of the diastolic portion of the beat waveform. We developed an iterative outlier detection algorithm to identify and remove the beats that are different from others in a recording. Finally, we tested the algorithm on a dataset consisting of more than 15 h of TCD data recorded from 48 stroke and 34 in-hospital control subjects.

RESULTS

We assessed the performance of the algorithm in the improvement of estimation of clinically important TCD parameters by comparing them to that of manual beat annotation. The results show that there is a strong correlation between the two, that demonstrates the algorithm has successfully recovered the clinically important features. We obtained significant improvement in estimating the TCD parameters using the algorithm accepted beats compared to using all beats.

SIGNIFICANCE

Our algorithm provides a valuable tool to clinicians for automated detection of the reliable portion of the data. Moreover, it can be used as a pre-processing tool to improve the data quality for automated diagnosis of pathologic beat waveforms using machine learning.

Transcranial Doppler Non-invasive Assessment of Intracranial Pressure, Autoregulation of Cerebral Blood Flow and Critical Closing Pressure during Orthotopic Liver Transplant

Transcranial Doppler (TCD) ultrasonography allows continuous non-invasive monitoring of cerebral blood flow velocity in a variety of clinical conditions. Recently, signal processing of TCD signals has provided several comprehensive parameters for the assessment of cerebral haemodynamics. In this work, we applied a TCD multimodal approach in patients with acute liver failure undergoing orthotopic liver transplant (OLT) to assess the clinical feasibility of using TCD for cerebral haemodynamics assessment in this setting. We retrospectively studied six patients undergoing OLT with continuous monitoring of arterial blood pressure and blood flow velocity in the middle cerebral artery. The main cerebral haemodynamic parameters assessed were non-invasive intracranial pressure, cerebral perfusion pressure, cerebral autoregulation, pulsatility index, critical closing pressure and diastolic closing margin. TCD monitoring revealed marked alterations of these parameters in the OLT setting, which could provide relevant clinical information when there is imminent risk of neurologic impairment.

Association Between Flow Acceleration in the Carotid Artery and Intracranial Aneurysms

OBJECTIVES

In physiologic pulsatile flow, velocity acceleration is an independent factor determining wall shear stress experienced by the vascular endothelium. The purpose of this study was to evaluate Doppler indices of systolic velocity acceleration in extracranial cerebral vessels and the occurrence of intracranial aneurysms.

METHODS

We reviewed medical records and 3.0-T brain magnetic resonance imaging with 3-dimensional time-of-flight magnetic resonance angiography of 1323 adults who underwent health checkups from June 2006 to November 2011, in whom 53 intracranial aneurysms were identified in 45 patients. Doppler ultrasound parameters of the carotid and vertebral arteries were analyzed in these 45 patients with aneurysms and compared with another 45 control participants matched for age and sex. We defined the maximum systolic acceleration (ACC_max ) as the maximum slope of the early phase of systolic acceleration on the Doppler waveform and the maximum acceleration index (AI_max ) as the ratio of the ACC_max and peak systolic velocity.

RESULTS

The Doppler analysis showed a significantly increased AI_max and ACC_max in the common carotid artery (CCA), internal carotid artery, and vertebral artery in the aneurysm group. A cutoff 13.89 s^-1 for the AI_max of the CCA had sensitivity of 80% with a negative predictive value of 99% for intracranial aneurysms.

CONCLUSIONS

This study suggests that the AI_max of the CCA with a cutoff of 13.89 s^-1 may be an alternative to 3-dimensional time-of-flight magnetic resonance angiography or computed tomographic angiography as a screening tool for intracranial aneurysms. Further prospective studies are needed to validate the diagnostic performance and cost-effectiveness of these indices for screening.

Research progress in ultrasound use for the diagnosis and treatment of cerebrovascular diseases

Cerebrovascular diseases pose a serious threat to human survival and quality of life and represent a major cause of human death and disability. Recently, the incidence of cerebrovascular diseases has increased yearly. Rapid and accurate diagnosis and evaluation of cerebrovascular diseases are of great importance to reduce the incidence, morbidity and mortality of cerebrovascular diseases. With the rapid development of medical ultrasound, the clinical relationship between ultrasound imaging technology and the diagnosis and treatment of cerebrovascular diseases has become increasingly close. Ultrasound techniques such as transcranial acoustic angiography, doppler energy imaging, three-dimensional craniocerebral imaging and ultrasound thrombolysis are novel and valuable techniques in the study of cerebrovascular diseases. In this review, we introduce some of the new ultrasound techniques from both published studies and ongoing trials that have been confirmed to be convenient and effective methods. However, additional evidence from future studies will be required before some of these techniques can be widely applied or recommended as alternatives.

Accuracy of Transcranial Sonography of the Substantia Nigra for Detection of Parkinson's Disease: A Systematic Review and Meta-analysis

A systematic review and meta-analysis were conducted to evaluate the diagnostic accuracy of substantia nigra hyper-echogenicity by transcranial sonography (TCS) for the diagnosis of Parkinson's disease (PD). PubMed, Embase and the Cochrane Library were electronically searched from inception to June 2018 for all relevant studies. The methodological quality of each study was evaluated by two independent reviewers, who used the Quality Assessment of Diagnostic Accuracy Studies 2 tool. Articles reporting information sufficient to calculate the sensitivity and specificity of TCS to diagnose PD were included. Statistical analysis included data pooling, heterogeneity testing, sensitivity analyses and forest meta-regression. Thirty-nine studies (3123 participants with PD) were analyzed. The pooled sensitivity and specificity of TCS were 0.84 (95% confidence interval: 0.81-0.87) and 0.85 (0.80-0.88), respectively, for differentiating PD from normal controls or participants with other parkinsonian syndromes. In the secondary outcome, PD participants exhibited a significant increase in substantia nigra areas than either normal controls (0.14 [0.12-0.16], p < 0.0001) or participants with other parkinsonian syndromes (0.11 [0.08-0.13], p < 0.0001). This meta-analysis revealed the high diagnostic performance of TCS in differentiating patients with PD from both normal controls and participants with other parkinsonian syndromes.