Diffusion tensor brain imaging at 0.55T: A feasibility study.

PURPOSE: To investigate the feasibility of diffusion tensor brain imaging at 0.55T with comparisons against 3T. METHODS: Diffusion tensor imaging data with 2 mm isotropic resolution was acquired on a cohort of five healthy subjects using both 0.55T and 3T scanners. The signal-to-noise ratio (SNR) of the 0.55T data was improved using a previous SNR-enhancing joint reconstruction method that jointly reconstructs the entire set of diffusion weighted images from k-space using shared-edge constraints. Quantitative diffusion tensor parameters were estimated and compared across field strengths. We also performed a test-retest assessment of repeatability at each field strength. RESULTS: After applying SNR-enhancing joint reconstruction, the diffusion tensor parameters obtained from 0.55T data were strongly correlated ( R 2 ≥ 0 . 70 $$ {R}^2\ge 0.70 $$ ) with those obtained from 3T data. Test-retest analysis showed that SNR-enhancing reconstruction improved the repeatability of the 0.55T diffusion tensor parameters. CONCLUSION: High-resolution in vivo diffusion MRI of the human brain is feasible at 0.55T when appropriate noise-mitigation strategies are applied.

Brainstorm-DUNEuro: An integrated and user-friendly Finite Element Method for modeling electromagnetic brain activity.

Human brain activity generates scalp potentials (electroencephalography - EEG), intracranial potentials (iEEG), and external magnetic fields (magnetoencephalography - MEG). These electrophysiology (e-phys) signals can often be measured simultaneously for research and clinical applications. The forward problem involves modeling these signals at their sensors for a given equivalent current dipole configuration within the brain. While earlier researchers modeled the head as a simple set of isotropic spheres, today's magnetic resonance imaging (MRI) data allow for a detailed anatomic description of brain structures and anisotropic characterization of tissue conductivities. We present a complete pipeline, integrated into the Brainstorm software, that allows users to automatically generate an individual and accurate head model based on the subject's MRI and calculate the electromagnetic forward solution using the finite element method (FEM). The head model generation is performed by integrating the latest tools for MRI segmentation and FEM mesh generation. The final head model comprises the five main compartments: white-matter, gray-matter, CSF, skull, and scalp. The anisotropic brain conductivity model is based on the effective medium approach (EMA), which estimates anisotropic conductivity tensors from diffusion-weighted imaging (DWI) data. The FEM electromagnetic forward solution is obtained through the DUNEuro library, integrated into Brainstorm, and accessible with either a user-friendly graphical interface or scripting. With tutorials and example data sets available in an open-source format on the Brainstorm website, this integrated pipeline provides access to advanced FEM tools for electromagnetic modeling to a broader neuroscience community.

Facets of facet joint interventions.

Facet joint (FJ) disease is a common cause of axial low back pain with many minimally invasive image-guided treatment options. This article discusses fluoroscopic and CT-guided intraarticular FJ injections, medial branch (MB) radiofrequency ablation (RFA), and lumbar facet synovial cyst (LFSC) aspiration, rupture, or fenestration. Additionally, the article will highlight medial branch blocks (MBBs) utilized to diagnose facet-mediated pain and to predict outcomes to RFA.

Visceral leishmaniasis in new foci areas of Nepal: Sources and extent of infection.

Background & objectives: The successful elimination program of visceral leishmaniasis (VL) in Nepal decreased the incidence to less than 1 per 10,000 population leading to the consolidation phase. However, new VL cases have been recorded from new districts, threatening the elimination goal. This study monitors the geographical spread of VL and identifies potential risk factors. Methods: VL data of 2017-2020 were obtained from the Epidemiology and Disease Control Division (EDCD) of Nepal and mapped. Telephonic interviews with 13 VL patients were conducted. Results: The incidence maps indicate that VL is spreading to new areas. The target incidence exceeded four times in hilly and twice in mountainous districts. VL cases occurred in 64 of 77 districts in all three regions (mountainous, hilly and Terai). Interviews showed a correlation between travel history (private, commercial and for studies) and the spread of VL cases to new foci. Interpretation & conclusion: One major challenge of VL elimination in the maintenance phase is the spread of infection through travelers to new foci areas, which needs to be under continuous surveillance accompanied by vector control activities. This should be confirmed by a large-scale analytical study.

Goal-directed Fluid Therapy in Neurosurgery: Three Feet from Gold?

How to cite this article: Kothekar AT, Mohanty R, Joshi AV. Goal-directed Fluid Therapy in Neurosurgery: Three Feet from Gold? Indian J Crit Care Med 2023;27(10):697-698.

Videolaryngoscopy: Channelizing through Intensive Care Unit Intubations.

How to cite this article: Kothekar AT, Wajekar AS, Joshi AV. Videolaryngoscopy: Channelizing through Intensive Care Unit Intubations. Indian J Crit Care Med 2023;27(2):85-86.

A robust variational autoencoder using beta divergence.

The presence of outliers can severely degrade learned representations and performance of deep learning methods and hence disproportionately affect the training process, leading to incorrect conclusions about the data. For example, anomaly detection using deep generative models is typically only possible when similar anomalies (or outliers) are not present in the training data. Here we focus on variational autoencoders (VAEs). While the VAE is a popular framework for anomaly detection tasks, we observe that the VAE is unable to detect outliers when the training data contains anomalies that have the same distribution as those in test data. In this paper we focus on robustness to outliers in training data in VAE settings using concepts from robust statistics. We propose a variational lower bound that leads to a robust VAE model that has the same computational complexity as the standard VAE and contains a single automatically-adjusted tuning parameter to control the degree of robustness. We present mathematical formulations for robust variational autoencoders (RVAEs) for Bernoulli, Gaussian and categorical variables. The RVAE model is based on beta-divergence rather than the standard Kullback-Leibler (KL) divergence. We demonstrate the performance of our proposed ß-divergence-based autoencoder for a variety of image and categorical datasets showing improved robustness to outliers both qualitatively and quantitatively. We also illustrate the use of our robust VAE for detection of lesions in brain images, formulated as an anomaly detection task. Finally, we suggest a method to tune the hyperparameter of RVAE which makes our model completely unsupervised.

Gastric Ultrasound: POCUSing an Intolerant GUT!

How to cite this article: Kothekar AT, Joshi AV. Gastric Ultrasound: POCUSing an Intolerant GUT! Indian J Crit Care Med 2022;26(9):981-982.

Robust brain network identification from multi-subject asynchronous fMRI data.

We describe a novel method for robust identification of common brain networks and their corresponding temporal dynamics across subjects from asynchronous functional MRI (fMRI) using tensor decomposition. We first temporally align asynchronous fMRI data using the orthogonal BrainSync transform, allowing us to study common brain networks across sessions and subjects. We then map the synchronized fMRI data into a 3D tensor (vertices × time × subject/session). Finally, we apply Nesterov-accelerated adaptive moment estimation (Nadam) within a scalable and robust sequential Canonical Polyadic (CP) decomposition framework to identify a low rank tensor approximation to the data. As a result of CP tensor decomposition, we successfully identified twelve known brain networks with their corresponding temporal dynamics from 40 subjects using the Human Connectome Project's language task fMRI data without any prior information regarding the specific task designs. Seven of these networks show distinct subjects' responses to the language task with differing temporal dynamics; two show sub-components of the default mode network that exhibit deactivation during the tasks; the remaining three components reflect non-task-related activities. We compare results to those found using group independent component analysis (ICA) and canonical ICA. Bootstrap analysis demonstrates increased robustness of networks found using the CP tensor approach relative to ICA-based methods.

Effective connectivity differs between focal cortical dysplasia types I and II.

OBJECTIVE: To determine whether brain connectivity differs between focal cortical dysplasia (FCD) types I and II. METHODS: We compared cortico-cortical evoked potentials (CCEPs) as measures of effective brain connectivity in 25 FCD patients with drug-resistant focal epilepsy who underwent intracranial evaluation with stereo-electroencephalography (SEEG). We analyzed the amplitude and latency of CCEP responses following ictal-onset single-pulse electrical stimulation (iSPES). RESULTS: In comparison to FCD type II, patients with type I demonstrated significantly larger responses in the electrodes near the ictal-onset zone (<50 mm). These findings persisted when controlling for the location of the epileptogenic zone, as noted in patients with temporal lobe epilepsies, as well as controlling for seizure type, as noted in patients with focal to bilateral tonic-clonic seizures (FBTCS). In type II, the root mean square (RMS) of CCEP responses dropped substantially from the early segment (10-60 ms) to the middle and late segments (60-600 ms). The middle and late CCEP latency segments showed the largest differences between FCD types I and II. SIGNIFICANCE: Focal cortical dysplasia type I may have a greater degree of cortical hyperexcitability as compared with FCD type II. In addition, FCD type II displays a more restrictive area of hyperexcitability in both temporal and spatial domains. In patients with FBTCS and type I FCD, the increased amplitudes of RMS in the middle and late CCEP periods appear consistent with the cortico-thalamo-cortical network involvement of FBTCS. The notable differences in degree and extent of hyperexcitability may contribute to the different postsurgical seizure outcomes noted between these two pathological substrates.

The Effectiveness of Intraosseous Basivertebral Nerve Radiofrequency Neurotomy for the Treatment of Chronic Low Back Pain in Patients with Modic Changes: A Systematic Review.

OBJECTIVE: Determine the effectiveness of intraosseous basivertebral nerve radiofrequency neurotomy for the treatment of chronic low back pain with type 1 or 2 Modic changes. DESIGN: Systematic review. POPULATION: Persons aged ≥18 years with chronic low back pain with type 1 or 2 Modic changes. INTERVENTION: Intraosseous basivertebral nerve radiofrequency neurotomy. COMPARISON: Sham, placebo procedure, active standard care treatment, or none. OUTCOMES: The primary outcome of interest was the proportion of individuals with ≥50% pain reduction. Secondary outcomes included ≥10-point improvement in function as measured by Oswestry Disability Index as well as ≥2-point reduction in pain score on the Visual Analog Scale or Numeric Rating Scale, and decreased use of pain medication. METHODS: Three reviewers independently assessed publications before May 15, 2020, in MEDLINE and Embase and the quality of evidence was evaluated using the Grades of Recommendation, Assessment, Development, and Evaluation framework. RESULTS: Of the 725 publications screened, seven publications with 321 participants were ultimately included. The reported 3-month success rate for ≥50% pain reduction ranged from 45% to 63%. Rates of functional improvement (≥10-point Oswestry Disability Index improvement threshold) ranged from 75% to 93%. For comparison to sham treatment, the relative risk of treatment success defined by ≥50% pain reduction and ≥10-point Oswestry Disability Index improvement was 1.25 (95% confidence interval [CI]: .88-1.77) and 1.38 (95% CI: 1.10-1.73), respectively. For comparison to continued standard care treatment the relative risk of treatment success defined by ≥50% pain reduction and ≥10-point Oswestry Disability Index improvement was 4.16 (95% CI: 2.12-8.14) and 2.32 (95% CI: 1.52-3.55), respectively. CONCLUSIONS: There is moderate-quality evidence that suggests this procedure is effective in reducing pain and disability in patients with chronic low back pain who are selected based on type 1 or 2 Modic changes, among other inclusion and exclusion criteria used in the published literature to date. Success of the procedure appears to be dependent on effective targeting of the BVN. Non-industry funded high-quality, large prospective studies are needed to confirm these findings.

Soil-transmitted helminthiasis in four districts in Bangladesh: household cluster surveys of prevalence and intervention status.

BACKGROUND: In 2016, after 8 years of twice-annual nationwide preventive chemotherapy (PC) administration to school-age children (SAC), the Bangladesh Ministry of Health & Family Welfare (MOHFW) sought improved impact and intervention monitoring data to assess progress toward the newly adopted goal of eliminating soil-transmitted helminthiasis (STH) as a public health problem. METHODS: We surveyed four Bangladeshi districts between August and October 2017. We conducted a multi-stage, cluster-sample, household survey which produced equal-probability samples for preschool-age children (PSAC; 1-4 years), SAC (5-14 years), and adults (≥ 15 years). Standardized questionnaires were administered, using Android-based smart phones running an Open Data Kit application. Stool samples were collected and testing for STH prevalence and infection intensity used the Kato-Katz technique. RESULTS: In all, 4318 stool samples were collected from 7164 participants. Estimates of STH prevalence by risk group in three of the four surveyed districts ranged from 3.4 to 5.0%, all with upper, 1-sided 95% confidence limits < 10%. However, STH prevalence estimates in Sirajganj District ranged from 23.4 to 29.1%. Infections in that district were spatially focal; four of the 30 survey clusters had > 50% prevalence in at least one risk group. Among all tested specimens, Ascaris lumbricoides was the most common STH parasite [8.2% (n = 352)], followed by Trichuris trichiura [0.9% (n = 37)], and hookworm [0.6% (n = 27)]. In each district, PC coverage among SAC was above the 75% program target but did not exceed 45% among PSAC in any district. Improved sanitation at home, school, or work was over 90% in all districts. CONCLUSIONS: In the three low-prevalence districts, the MOHFW is considering decreasing the frequency of mass drug administration, per World Health Organization (WHO) guidelines. Also, the MOHFW will focus programmatic resources and supervisory efforts on Sirajganj District. Despite considering WHO guidance, the MOHFW will not expand PC administration to women of reproductive age partly due to the low prevalence of hookworm and T. trichiura, the STH parasites that contribute most to morbidity in that risk group. Data collected from surveys such as ours would help effectively guide future STH control efforts in Bangladesh and elsewhere.

Systematic review of diagnostic accuracy of patient history, clinical findings, and physical tests in the diagnosis of lumbar spinal stenosis.

PURPOSE: To update evidence of diagnostic potential for identification of lumbar spinal stenosis (LSS) based on demographic and patient history, clinical findings, and physical tests, and report posttest probabilities associated with test findings. METHODS: An electronic search of PubMed, CINAHL and Embase was conducted combining terms related to low back pain, stenosis and diagnostic accuracy. Prospective or retrospective studies investigating diagnostic accuracy of LSS using patient history, clinical findings and/or physical tests were included. The risk of bias and applicability were assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS 2) tool. Diagnostic accuracy including sensitivities (SN), specificities (SP), likelihood ratios (+LR and -LR) and posttest probabilities (+PTP and -PTP) with 95% confidence intervals were summarized. RESULTS: Nine studies were included (pooled n = 36,228 participants) investigating 49 different index tests (30 demographic and patient history and 19 clinical findings/physical tests). Of the nine studies included, only two exhibited a low risk of bias and seven exhibited good applicability according to QUADAS 2. The demographic and patient history measures (self-reported history questionnaire, no pain when seated, numbness of perineal region) and the clinical findings/physical tests (two-stage treadmill test, symptoms after a March test and abnormal Romberg test) highly improved positive posttest probability by > 25% to diagnose LSS. CONCLUSION: Outside of one study that was able to completely rule out LSS with no functional neurological changes none of the stand-alone findings were strong enough to rule in or rule out LSS. These slides can be retrieved under Electronic Supplementary Material.

Barriers of Visceral Leishmaniasis reporting and surveillance in Nepal: comparison of governmental VL-program districts with non-program districts.

OBJECTIVES: At the time when Nepal is on the verge of reaching the maintenance phase of the Visceral Leishmaniasis (VL) elimination program, the country is facing new challenges. The disease has expanded to 61 of the country's 75 districts including previously non-endemic areas where there is no control or patient management program in place. This study aimed to assess which elements of the surveillance and reporting systems need strengthening to identify cases at an early stage, prevent further transmission and ensure sustained VL elimination. METHODS: In a cross-sectional mixed-method study, we collected data from two study populations in VL program and non-program districts. From February to May 2016, structured interviews were conducted with 40 VL patients, and 14 in-depth and semi-structured interviews were conducted with health managers. RESULTS: The median total delay from onset of symptoms to successful reporting to the Ministry of Health was 68.5 days in the VL-program and 83 days in non-program districts. The difference in patient's delay from the onset of symptoms to seeking health care was 3 days in VL-program and 20 days in non-program districts. The diagnostic delay (38.5 days and 36 days, respectively), treatment delay (1 vs. 1 days) and reporting delay (45 vs. 36 days) were similar in program and non-program districts. The diagnostic delay increased three-fold from 2012, while treatment and reporting delay remained unchanged. The main barriers to surveillance were: (i) lack of access and awareness in non-program districts; (ii) growing private sector not included in and not participating to referral, treatment and reporting; (iii) lack of cooperation and coordination among stakeholders for training and deployment of interventions; (iv) insufficient validation, outreach and process optimisation of the reporting system. CONCLUSIONS: Corrective measures are needed to maintain the achievements of the VL elimination campaign and prevent resurgence of the disease in Nepal. A clear patient referral structure, reinforcement of report notification and validation and direct relay of data by local hospitals and the private sector to the district health offices are needed to ensure prompt treatment and timely and reliable information to facilitate a responsive system of interventions.

Anemia predicts lower white matter volume and cognitive performance in sickle and non-sickle cell anemia syndrome.

Severe chronic anemia is an independent predictor of overt stroke, white matter damage, and cognitive dysfunction in the elderly. Severe anemia also predisposes to white matter strokes in young children, independent of the anemia subtype. We previously demonstrated symmetrically decreased white matter (WM) volumes in patients with sickle cell disease (SCD). In the current study, we investigated whether patients with non-sickle anemia also have lower WM volumes and cognitive dysfunction. Magnetic Resonance Imaging was performed on 52 clinically asymptomatic SCD patients (age = 21.4 ± 7.7; F = 27, M = 25; hemoglobin = 9.6 ± 1.6 g/dL), 26 non-sickle anemic patients (age = 23.9 ± 7.9; F = 14, M = 12; hemoglobin = 10.8 ± 2.5 g/dL) and 40 control subjects (age = 27.7 ± 11.3; F = 28, M = 12; hemoglobin = 13.4 ± 1.3 g/dL). Voxel-wise changes in WM brain volumes were compared to hemoglobin levels to identify brain regions that are vulnerable to anemia. White matter volume was diffusely lower in deep, watershed areas proportionally to anemia severity. After controlling for age, sex, and hemoglobin level, brain volumes were independent of disease. WM volume loss was associated with lower Full Scale Intelligence Quotient (FSIQ; P = .0048; r2 = .18) and an abnormal burden of silent cerebral infarctions (P = .029) in males, but not in females. Hemoglobin count and cognitive measures were similar between subjects with and without white-matter hyperintensities. The spatial distribution of volume loss suggests chronic hypoxic cerebrovascular injury, despite compensatory hyperemia. Neurocognitive consequences of WM volume changes and silent cerebral infarction were strongly sexually dimorphic. Understanding the possible neurological consequences of chronic anemia may help inform our current clinical practices.

Childhood Music Training Induces Change in Micro and Macroscopic Brain Structure: Results from a Longitudinal Study.

Several studies comparing adult musicians and nonmusicians have shown that music training is associated with structural brain differences. It is not been established, however, whether such differences result from pre-existing biological traits, lengthy musical training, or an interaction of the two factors, or if comparable changes can be found in children undergoing music training. As part of an ongoing longitudinal study, we investigated the effects of music training on the developmental trajectory of children's brain structure, over two years, beginning at age 6. We compared these children with children of the same socio-economic background but either involved in sports training or not involved in any systematic after school training. We established at the onset that there were no pre-existing structural differences among the groups. Two years later we observed that children in the music group showed (1) a different rate of cortical thickness maturation between the right and left posterior superior temporal gyrus, and (2) higher fractional anisotropy in the corpus callosum, specifically in the crossing pathways connecting superior frontal, sensory, and motor segments. We conclude that music training induces macro and microstructural brain changes in school-age children, and that those changes are not attributable to pre-existing biological traits.

The Source and the Course of the Articular Branches to the T4-T8 Zygapophysial Joints.

OBJECTIVE: To define the source and the course of the articular branches to the midthoracic zygapophysial ("z") joints. DESIGN: Cadaveric dissection. SETTING: The Gross Anatomy Laboratory of the Duke University School of Medicine. SUBJECTS: Ten human cadaveric thoraces. METHODS: Gross and stereoscopic dissection of dorsal rami T4-T8 was performed bilaterally on 10 adult embalmed cadavers. The medial and lateral branches were traced to their origins from the dorsal rami, and the course of the articular nerves was documented through digital photography. Radio-opaque wire (20 gauge) was applied to the nerves. Fluoroscopic images were obtained to delineate their radiographic course with respect to osseous landmarks. RESULTS: Forty-eight inferior articular branches were identified. Three (6.3%) originated from the medial branch and 44 (91.7%) from the dorsal ramus. One was indeterminate. Fifty-one superior articular branches were identified. Eight (15.7%) originated from the medial branch and 43 (84.3%) from the dorsal ramus. In 12% of cases (6/50), there was side-to-side asymmetry in the origins of the articular branches. Nerves were commonly suspended in the intertransverse space. The articular branches contacted an osseous structure in only 39% of cases. As previously reported, a "descending branch" was not identified in any specimen. CONCLUSIONS: Articular branches to the T4-T8 z-joints have substantial inter- and intraspecimen variability of origin. They typically arise from the dorsal ramus rather than the medial branch and frequently do not contact any osseous structure to allow percutaneous needle placement.

Improved Dose Estimates for Fluoroscopically Guided Lumbar Epidural Injections.

OBJECTIVE: The goal of the study was to determine the potential impact of system inaccuracies and table attenuation on fluoroscope-reported dose values. DESIGN: An Institutional Review Board-approved study was conducted to collect detailed acquisition and patient exposure data for fluoroscopy-guided lumbar epidural injections. BACKGROUND: System-reported dosimetry values, especially the air Kinetic Energy Released per unit MAss and dose-area product metrics, are routinely used for estimating the radiation burden to patients undergoing fluoroscopy-guided procedures. However, these metrics do not account for other factors, such as acquisition geometry, where the table may attenuate a substantial fraction of the x-ray intensity, and system dosimetry inaccuracies, which are only required to be accurate within ±35%. METHODS: Acquisition data from 46 patients undergoing fluoroscopy-guided lumbar epidural injections were collected to better estimate the true incident dose-area product. Gantry angles, x-ray technique factors, and field sizes were collected to characterize each procedure. Additionally, the fluoroscope dosimetry accuracy and table attenuation properties were evaluated as a function of kVp to generate the correction factors necessary for accurate dosimetry estimates. RESULTS: The system-reported values overestimated the total patient entrance dose-area product by an average of 34% (13-44%). Errors may be substantially higher for systems with less accurate fluoroscopes or more anterior-posterior projections. Correcting system-reported dosimetry values for systematic inaccuracies and variability can substantially improve fluoroscopic dose values. CONCLUSIONS: Including corrections for system output inaccuracies and acquisition factors such as table attenuation is necessary for any reliable assessment of radiation burden to patients associated with fluoroscopy-guided procedures.

A clinical comparative study to assess the efficacy of a new centric registration technique with a conventional technique.

AIM: The aim and objectives of this study were to assess and compare the efficacy of a new copyrighted technique (wax ball technique, L-77997/2018) and design (denture base design for the wax ball technique, L-78006/2018) for recording centric relation (CR). SETTINGS AND DESIGNS: In vivo - comparative study. MATERIALS AND METHODS: This study was conducted on sixty consented edentulous patients. The study participants were divided into Group I and Group II. CR in Group I patients was recorded using Dawson's bimanual technique (technique 1). For participants in Group II, CR was recorded using the authors' copyrighted technique (technique 2). Time taken and accuracy of CR records by both the techniques were evaluated. STATISTICAL ANALYSIS USED: Descriptive statistics such as frequency and percentage were calculated for categorical variables, mean and standard deviation were calculated for quantitative variables. Independent t-test was used to compare the time taken to record the CR between the two groups. The accuracy of both the techniques was assessed by Mann-Whitney U-test. RESULTS: The mean time taken for technique 1 was 56.47 s, whereas for technique 2, it was 5.97 s, with an overall mean difference of 50.5 s between the two techniques. Both techniques were found to be accurate, as the CR recorded during jaw relation matched with CR during trial in all the cases in both the groups (frequency 30 (N) and cumulative percentage 100%). CONCLUSION: From the study, it was found that, time taken for technique 2 was statistically less compared to that of technique 1, and both the techniques were found to be equally accurate.

Are you thinking what I'm thinking? Synchronization of resting fMRI time-series across subjects.

We describe BrainSync, an orthogonal transform that allows direct comparison of resting fMRI (rfMRI) time-series across subjects. For this purpose, we exploit the geometry of the rfMRI signal space to propose a novel orthogonal transformation that synchronizes rfMRI time-series across sessions and subjects. When synchronized, rfMRI signals become approximately equal at homologous locations across subjects. The method is based on the observation that rfMRI data exhibit similar connectivity patterns across subjects, as reflected in the pairwise correlations between different brain regions. We show that if the data for two subjects have similar correlation patterns then their time courses can be approximately synchronized by an orthogonal transformation. This transform is unique, invertible, efficient to compute, and preserves the connectivity structure of the original data for all subjects. Analogously to image registration, where we spatially align structural brain images, this temporal synchronization of brain signals across a population, or within-subject across sessions, facilitates cross-sectional and longitudinal studies of rfMRI data. The utility of the BrainSync transform is illustrated through demonstrative simulations and applications including quantification of rfMRI variability across subjects and sessions, cortical functional parcellation across a population, timing recovery in task fMRI data, comparison of task and resting state data, and an application to complex naturalistic stimuli for annotation prediction.