OBJECTIVE: Determining the long-term success of endoscopic third ventriculostomy (ETV) remains challenging. This study aimed to investigate the impact of clinical and radiological factors on ETV success in pediatric patients with hydrocephalus.
METHODS: The study included patients < 18 years old with hydrocephalus who underwent ETV between March 2014 and May 2021. Data including patient age, gender, history of previous shunt surgery, previous external ventricular drain placement, intraventricular hemorrhage history, and postoperative meningitis were extracted from medical records. Imaging features such as aqueductal stenosis, third ventricle floor bowing, displaced lamina terminalis, pulsatility index (PI), and maximum diameter of the cortical subarachnoid space (CSAS) were recorded for each patient using preoperative CT scans. Two independent neurosurgeons measured the CSAS maximum diameter and the PI. CSAS measurements were obtained on axial slices of the preoperative CT scans, whereas the PI was based on intraoperative third ventricle pulsatility. Patients were followed up for 1 year after surgery, with failure defined as the need for ventriculoperitoneal shunt (VPS) placement or death attributable to hydrocephalus.
RESULTS: Ninety-eight children with a mean age of 16.39 ± 19.07 months underwent ETV for hydrocephalus. No deaths were recorded, but over 6 months and 1 year of follow-up, 12.2% and 22.4% of patients, respectively, experienced documented ETV failure requiring VPS placement. At the 6-month follow-up, a smaller maximum diameter of the CSAS was significantly associated with ETV failure; multivariate analysis revealed that CSAS maximum diameter was a predictor of 6-month ETV failure. At the 1-year follow-up, a lower PI was significantly associated with ETV failure, and multivariate analysis confirmed the PI as a significant predictor of ETV failure within 1 year after surgery. CSAS and PI measurements were repeated to assess interrater reliability: the intraclass correlation coefficients were 0.897 and 0.669 for CSAS and PI, respectively.
CONCLUSIONS: This study found that the CSAS maximum diameter and the PI are predictors of ETV failure at 6 months and 1 year, respectively. These findings highlight the importance of considering specific factors such as the CSAS and PI when assessing the likelihood of ETV success in pediatric patients with hydrocephalus. Further research and consideration of these factors may help optimize patient selection and improve outcomes for those undergoing ETV as a treatment for hydrocephalus.

UNASSIGNED: To compare the ocular blood flow in glaucomatous eyes and normal healthy eyes. This study compares open-angle glaucoma patients to healthy adults by measuring various parameters in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary artery (SPCA).
UNASSIGNED: A total of 50 glaucomatous eyes and 50 normal eyes were included in a prospective case-control study over 1 year. The color Doppler imaging (CDI) was conducted using a noninvasive linear multifrequency probe with a frequency range of 5-9 MHz. OA, CRA, and SPCA were measured for peak systolic velocity (PSV), end-diastolic volume (EDV), pulsatility index (PI), and resistivity index (RI).
UNASSIGNED: When compared with controls, PSV was decreased in all three vessels, with the results being remarkable only in CRA. The EDV also showed a remarkable decrease in all three vessels. Additionally, all three vessels showed significant increases in PI and RI except OA, p-value < 0.05.
UNASSIGNED: Blood velocity is decreased, and resistive indices are increased in glaucomatous eyes compared with normal eyes. Variations in ocular blood flow could be a cause or consequence of glaucomatous optic neuropathy and are an important predictor of disease progression.
UNASSIGNED: Murugesan MAD, Venkat P, Basetti B. Comparison of Ocular Blood Flow in Glaucomatous Eyes and Nonglaucomatous Eyes at a Tertiary Hospital in South India: A Prospective Case-control Study. J Curr Glaucoma Pract 2024;18(2):45-50.

OBJECTIVE: Dynamic Ultrasound Localization Microscopy (DULM) has first been developed for non-invasive Pulsatility measurements in the rodent brain. DULM relies on the localization and tracking of microbubbles (MBs) injected into the bloodstream, to obtain highly resolved velocity and density cine-loops. Previous DULM techniques required ECG-gating, limiting its application to specific datasets, and increasing acquisition time. The objective of this study is to eliminate the need for ECG-gating in DULM experiments by introducing a motion-matching method for time registration.
METHODS: We developed a motion-matching algorithm based on tissue Doppler that leverages the cyclic tissue motion within the brain. Tissue Doppler was estimated for each group of frames in the acquisitions, at multiple locations identified as local maxima in the skin above the skull. Subsequently, each group of frames was time-registered to a reference group by delaying it based on the maximum correlation value between their respective tissue Doppler signals. This synchronization ensured that each group of frames aligned with the brain tissue motion of the reference group, and consequently, with its cardiac cycle. As a result, velocities of MBs could be averaged to retrieve flow velocity variations over time.
RESULTS: Initially validated in ECG-gated acquisitions in a rat model (n = 1), the proposed method was successfully applied in a mice model in 2D (n = 3) and in a feline model in 3D (n = 1). Performing time-registration with the proposed motion-matching method or by using ECG-gating leads to similar results. For the first time, dynamic velocity and density cine-loops were extracted without the need for any information on the animal ECG, and complex dynamic markers such as the Pulsatility index were estimated.
CONCLUSIONS: Results suggest that DULM can be performed without external gating, enabling the use of DULM on any ULM dataset where enough MBs are detectable. Time registration by motion-matching represents a significant advancement in DULM techniques, making DULM more accessible by simplifying its experimental complexity.

OBJECTIVE: The compensatory mechanisms supporting cerebral perfusion throughout head-up tilt (HUT) in patients with vasovagal syncope (VVS) remain unclear. We tested the hypothesis that increased cerebrovascular compliance (Ci) and decreased cerebrovascular resistance (CVR) support cerebral blood velocity (CBV) during pre-syncope in VVS.
METHODS: Finger arterial blood pressure (ABP) and right middle cerebral artery blood velocity (CBV) were recorded in 15 individuals diagnosed with VVS (n = 11 female, mean age: 40 ± 16 years, mean body mass index: 24.9 ± 4.0 kg/m2) at supine rest and during HUT (80 degree angle). Individual ABP and CBV waveforms during VVS were input into a modified Windkessel model to calculate Ci and ohmic CVR. Gosling\'s pulsatility index (Pi; pulse amplitude/mean CBV) was calculated.
RESULTS: Diastolic ABP, systolic ABP, mean ABP (72 ± 11 to 51 ± 12 mmHg), and CVR decreased progressively during presyncope (all P ≤ 0.04). As expected, systolic CBV was sustained (all P ≥ 0.29) while diastolic and mean CBV (51 ± 13 to 38 ± 13 mmHg) fell during presyncope (all P ≤ 0.04). Both Ci and Pi increased during presyncope (128 ± 97 and 60 ± 41%, respectively; all P ≤ 0.049) and were positively correlated (R2 = 0.79, P < 0.01). Increased Ci contributed to changes in mean CBV (P < 0.01) but decreased CVR did not (P = 0.28).
CONCLUSIONS: These data provide evidence that Ci increases during presyncope in patients with VVS and is likely involved in the maintenance of systolic CBV during a fall in diastolic CBV. However, this regulation is not sufficient to preserve CBV in the presence of such extreme and progressive reductions in ABP.

OBJECTIVE: This study compares transcranial Doppler (TCD) Pulsatility Index (PI) and Resistivity Index (RI) with intra-operative CSF opening pressure measured by manometric technique during ventriculoperitoneal (V-P) shunt in children with hydrocephalus.
METHODS: It was a prospective, hospital-based study performed among patients diagnosed with hydrocephalus. Patients had TCD ultrasonography before V-P shunt. The TCD sonography was repeated within 1 week post-op, and at 1 month post-op. The PI and RI were retrieved after insonating the middle cerebral artery. Ventricular CSF opening pressure was measured. Associations between TCD indices and CSF pressure were determined using the t-test and the Wilcoxon rank /Mann-Whitney tests where the normality test failed. A p-value of < 0.05 was considered significant for associations.
RESULTS: Fifty-two patients were enrolled with a mean age of 9.9 ± 11.5 months. Of these, 41 (78.8%) were aged ≤ 12 months. The mean CSF opening pressure was 21.4 ± 9.0. When raised, ICP was defined as opening pressure > 15 cm of H2O, high PI (≥ 1.19), and high RI (> 0.8) diagnosed it with a sensitivity of 55% and 50%, respectively. The mean pre-operative PI (1.17 ± 0.56) reduced to 0.96 (Z =  - 2.032, p = 0.042), while that of RI (0.66 ± 0.17) also decreased to 0.58 (t = 2.906, p = 0.044) after V-P shunt surgery. A strong positive correlation exists between a reduction in PI and RI after V-P shunt (r = 0.743, p = 0.014).
CONCLUSIONS: Both PI and RI significantly decrease following V-P shunt, but a single reading has a poor sensitivity in predicting ICP.

OBJECTIVE: Aneurysm number (An) is a novel prediction tool utilizing parameters of pulsatility index (PI) and aneurysm geometry. An has been shown to have the potential to differentiate intracranial aneurysm (IA) rupture status. The objective of this study is to investigate the feasibility and accuracy of An for IA rupture status prediction using Australian based clinical data.
METHODS: A retrospective study was conducted across three tertiary referral hospitals between November 2017 and November 2020 and all saccular IAs with known rupture status were included. Two sets of An values were calculated based on two sets of PI values previously reported in the literature.
RESULTS: Five hundred and four IA cases were included in this study. The results demonstrated no significant difference between ruptured and unruptured status when using An ≥1 as the discriminator. Further analysis showed no strong correlation between An and IA subtypes. The area under the curve (AUC) indicated poor performance in predicting rupture status (AUC1 = 0.55 and AUC2 = 0.56).
CONCLUSIONS: This study does not support An ≥1 as a reliable parameter to predict the rupture status of IAs based on a retrospective cohort. Although the concept of An is supported by hemodynamic aneurysm theory, further research is needed before it can be applied in the clinical setting.
CONCLUSIONS: This study demonstrates that the novel prediction tool, An, proposed in 2020 is not reliable and that further research of this hemodynamic model is needed before it can be incorporated into the prediction of IA rupture status.

OBJECTIVE: This study investigated the correlation between the pulsatility index (PI) of the middle cerebral artery with the total burden of cerebral small vessel disease and cognitive impairment.
METHODS: Information on patients hospitalized in the Department of Neurology was collected retrospectively. These patients had complete clinical and laboratory data. The middle cerebral artery PI was measured using transcranial Doppler, a Mini-Mental State Examination (MMSE) was used to assess cognitive function, and the total cerebral small vessel disease burden was assessed using magnetic resonance imaging. Patients were grouped according to their scores for total imaging burden of cerebral small vessel disease and cognitive function. Logistic regression analysis assessed the association between the PI, total imaging burden, and cognitive impairment. Spearman analysis was used to evaluate the correlation between the PI and total imaging burden and cognitive impairment, and receiver operating characteristic (ROC) curves were used to determine the predictive value of the PI for cognitive function.
RESULTS: The PI was higher in the cognitive impairment (CI) group than in the no-CI group. Binary logistic regression analysis showed that increased PI was an independent risk factor for CI (OR = 1.582; 95% CI: 1.043-2.401; p = .031) and total imaging burden (OR = 1.842; 95% CI: 1.274-2.663; p = .001). Spearman analysis found that the PI correlated negatively with the MMSE score (r = -.627, p < .001). ROC curve analysis showed the PI predicted CI with an area under the curve of 0.784. The PI combined with the total imaging burden predicted CI in cerebral small vessel disease with an area under the curve of 0.832.
CONCLUSIONS: An increased PI was associated with CI and a high imaging burden in cerebral small vessel disease patients. The PI combined with the total burden score shows a high predictive value for CI.

OBJECTIVE: To evaluate the vascular impedance of the pulmonary arteries in fetuses with tetralogy of Fallot (TOF) by Doppler echocardiography.
METHODS: A total of 42 fetuses with TOF (TOF group) and 84 gestational age-matched normal fetuses (control group) were prospectively collected from the Second Xiangya Hospital of Central South University from August 2022 to January 2023. The severity of TOF was classified into mild TOF (z score ≥-2), moderate TOF (-4 < z score < -2), or severe TOF (z score ≤-4) according to the z score value of the pulmonary annulus diameter. The pulsatility index (PI) of the main pulmonary artery (MPA), distal left pulmonary artery (DLPA), and distal right pulmonary artery (DRPA) were measured by pulsed-wave Doppler. The differences in clinical data and echocardiographic parameters between TOF group, control group, and TOF subgroups were compared.
RESULTS: Compared with the control group, MPA-PI increased significantly, whereas DLPA-PI and DRPA-PI decreased in TOF group (all P < .001). There were no significant differences in MPA-PI and DRPA-PI among mild TOF, moderate TOF, and severe TOF (all P > .05). However, DLPA-PI decreased significantly in severe TOF compared with mild TOF (P < .05).
CONCLUSIONS: Fetuses with TOF presented increased vascular impedance in the pulmonary trunk and decreased impedance in distal pulmonary artery branches. Further large and follow-up studies are needed to demonstrate the associations between those changed vascular impedances and the development of PA in patients with TOF.

UNASSIGNED: Resistive index (RI) and pulsatility index (PI) assessed on carotid Doppler assess the hemodynamic status of cranial vasculature. They are related to the severity of stroke and help determine the overall outcome. This study was done to compare the hospital stay and stroke severity with RI and PI of both internal carotid arteries.
UNASSIGNED: Patients >18 years of age presenting within 48 h of anterior circulation stroke (either ischemic or hemorrhagic) were included. They were divided into two groups based on their length of stay (LOS). They were assessed clinically on days 1, 3, and 5, and underwent a carotid Doppler study on the same days. The Doppler parameters were correlated with the LOS and stroke severity for possible associations.
UNASSIGNED: One hundred and one patients were included. Forty-seven patients had a favorable outcome based on LOS. In this group, significant decrease in RI and PI scores was seen from days 1 to 3. In patients with unfavorable outcome, there was a significant increase in PI on days 1-3 and days 1-5. The National Institutes of Health Stroke Scale decreased significantly from days 1 to 5 in favorable group.
UNASSIGNED: For those with an unfavorable outcome and prolonged LOS, PI continues to increase suggesting a failure of autoregulation. Carotid Doppler can be a simple bedside tool to predict outcome in patients with acute stroke.