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Background: Hemoglobin concentration and diffusion-weighted imaging (DWI) ischemic lesions are separately known to be associated with poor intracerebral hemorrhage (ICH) outcomes. While hemoglobin concentrations have known relationships with ischemic stroke, it is unclear whether hemoglobin concentration is associated with DWI ischemic lesions after ICH. We sought to investigate the hypothesis that hemoglobin concentrations would associate with DWI lesions after ICH and further investigated their relationships with clinical outcomes. Methods: Supratentorial ICH patients enrolled between 2010 and 2016 to a prospective, multicenter, observational cohort study (ERICH study [Ethnic/Racial Variations of Intracerebral Hemorrhage]) were assessed. Patients from this study with baseline, admission hemoglobin, and hospitalization magnetic resonance imaging were analyzed. Hemoglobin was examined as the primary exposure variable defined as a continuous variable (g/dL). Magnetic resonance imaging DWI ischemic lesion presence was assessed as the primary radiographic outcome. Primary analyses assessed relationships of hemoglobin with DWI lesions. Secondary analyses assessed relationships of DWI lesions with poor 3-month outcomes (modified Rankin Scale score, 4–6). These analyses were performed using separate multivariable logistic regression models adjusting for relevant covariates. Results: Of 917 patients with ICH analyzed, mean baseline hemoglobin was 13.8 g/dL (±1.9), 60% were deep ICH, and DWI lesions were identified in 27% of the cohort. In our primary analyses, increased hemoglobin, defined as a continuous variable, was associated with DWI lesions (adjusted odds ratio, 1.21 per 1 g/dL change in hemoglobin [95% CI, 1.07–1.37]) after adjusting for sex, race, ICH severity, time to magnetic resonance imaging, and acute blood pressure change. In secondary analyses, DWI lesions were associated with poor 3-month outcomes (adjusted odds ratio, 1.83 [95% CI, 1.24–2.69]) after adjusting for similar covariates. Conclusions: We identified novel relationships between higher baseline hemoglobin concentrations and DWI ischemic lesions in patients with ICH. Further studies are required to clarify the role of hemoglobin concentration on both cerebral small vessel disease pathophysiology and ICH outcomes.

Introduction: Hematocrit at both low and high extremes can result in both hypoxia and thrombosis respectively. While both scenarios may predispose to ischemia, it is unclear whether hematocrit associates with small vessel cerebrovascular lacunar infarcts. Hypothesis: Hematocrit levels will associate with both asymptomatic and symptomatic cerebrovascular lacunar infarcts in stroke-free participants and ischemic stroke patients, respectively. Methods: A cross sectional observational analysis of a prospective, population-based cohort study of stroke-free, older adult (>50) participants from the Northern Manhattan study (NOMAS) receiving baseline hematocrit testing and MRI between 2003-2008 were analyzed. A second, single center prospective cohort of admitted adult ischemic stroke patients receiving baseline hematocrit testing and MRI between 2005-2018 was evaluated. Associations of hematocrit with covert, asymptomatic chronic lacunar infarcts from stroke-free participants in NOMAS were assessed using general additive models after adjusting for relevant covariates. Separate analyses were performed to assess associations of hematocrit with symptomatic acute lacunar infarct stroke etiology using similar adjusted models for patients admitted and enrolled into the ischemic stroke registry. Results: Of 1218 NOMAS participants analyzed, 6% had covert chronic lacunar infarcts. The association between hematocrit and covert chronic lacunar infarcts was U-shaped (X2: 9.21; p-value: 0.03). In the 1489 patients from the ischemic stroke registry, 23% were identified to have symptomatic acute lacunar infarcts. Linear relationships were identified with higher hematocrit and symptomatic acute lacunar infarct etiology (adjusted coefficient beta: 0.020; standard error: 0.009; p=0.03). Conclusions: We identified relationships of hematocrit with both asymptomatic and symptomatic lacunar infarcts in both stroke-free and ischemic stroke cohorts, respectively. There may be a relevant role of red blood cell volumes with ischemic cerebral small vessel disease pathophysiology. However, further studies are required to clarify the mechanisms behind these relationships.

Introduction: Hemoglobin concentrations and diffusion weighted imaging (DWI) lesions are separately known to be associated with poor intracerebral hemorrhage (ICH) outcomes. Though hemoglobin concentrations are related to both hypoxia and thrombosis at their extremes, it is unknown whether hemoglobin concentrations relate to DWI lesions after ICH. Methods: Spontaneous, supratentorial ICH patients with available baseline hemoglobin and hospitalized MRI data enrolled into a multicenter cohort study between 2010-2016 were analyzed. Baseline hemoglobin was assessed as both a continuous variable (g/dL) and categorical variable (/=15 g/dL). Primary analyses assessed relationships of baseline hemoglobin with MRI DWI lesions. Secondary analyses assessed independent relationships of hemoglobin and DWI lesions with poor 3-month outcomes (modified Rankin Scale [mRS] 4-6). Separate multivariable regression models assessed these relationships after adjusting for relevant covariates. Results: Of 917 ICH patients analyzed, the mean baseline hemoglobin was 13.8 g/dL (+/-1.9), 60% were deep ICH, and DWI lesions were identified in 27% of the cohort. In our primary analyses, increased hemoglobin, defined as a continuous variable, was associated with DWI lesions (adjusted OR 1.21, 95% CI: 1.07-1.37) after adjusting for sex, race, ICH severity, time to MRI, and blood pressure treatment change. In secondary analyses, DWI lesions were associated with poor 3-month outcomes (adjusted OR 1.83, 95% CI: 1.24-2.69) adjusting for similar covariates. We identified associations of low hemoglobin categories, when referenced to hemoglobin 13 to /=15 g/dL) with poor outcomes were smaller and imprecise (adjusted OR 1.39, 95% CI: 0.89-2.17). Conclusions: We identified novel relationships between higher baseline hemoglobin concentrations and DWI lesions in ICH patients. Further studies are required to clarify the role of hemoglobin concentrations on both cerebral small vessel disease pathophysiology and ICH outcomes.

Gene editing in the mammalian brain has been challenging because of the restricted transport imposed by the blood-brain barrier (BBB). Current approaches rely on local injection to bypass the BBB. However, such administration is highly invasive and not amenable to treating certain delicate regions of the brain. We demonstrate a safe and effective gene editing technique by using focused ultrasound (FUS) to transiently open the BBB for the transport of intravenously delivered CRISPR/Cas9 machinery to the brain.

Focused ultrasound (FUS) in combination with systemically injected microbubbles can be used to non-invasively open the blood-brain barrier (BBB) in targeted regions for a variety of therapeutic applications. Over the past two decades, preclinical research into the safety and efficacy of FUS-induced BBB opening has proven this technique to be transient and efficacious, propelling FUS-induced BBB opening into several clinical trials in recent years. However, as clinical trials further progress, the neuroinflammatory response to FUS-induced BBB opening needs to be better understood. In this study, we provide further insight into the relationship of microbubble cavitation and the resulting innate immune response to FUS-induced BBB opening. By keeping ultrasound parameters fixed (i.e. frequency, pressure, pulse length, etc.), three groups of mice were sonicated using a real-time cavitation controller until a target cavitation dose was reached (1 [Formula: see text] 10(7) V(2)•s, 5 [Formula: see text] 10(7) V(2)•s, 1 [Formula: see text] 10(8) V(2)•s). The change in relative gene expression of the mouse inflammatory cytokines and receptors were evaluated at three different time-points (6 h, 24 h, and 72 h) after FUS. At both 6 and 24 h time-points, significant changes in relative gene expression of inflammatory cytokines and receptors were observed across all cavitation groups. However, the degree of changes in relative expression levels and the number of genes with significant changes in expression varied across the cavitation groups. Groups with a higher cavitation dose exhibited both greater changes in relative expression levels and greater number of significant changes. By 72 h, the gene expression levels returned to baseline in all cavitation dose groups, signifying a transient inflammatory response to FUS-induced BBB opening at the targeted cavitation dose levels. Furthermore, the real-time cavitation controller was able to produce consistent and significantly different BBB permeability enhancement volumes across the three different cavitation dose groups. These results indicate that cavitation monitoring and controlling during FUS-induced BBB opening can be used to potentially modulate or limit the degree of neuroinflammation, further emphasizing the importance of implementing cavitation controllers as FUS-induced BBB opening is translated into the clinic.

An emerging approach with potential in improving the treatment of neurodegenerative diseases and brain tumors is the use of focused ultrasound (FUS) to bypass the blood–brain barrier (BBB) in a non-invasive and localized manner. A large body of pre-clinical work has paved the way for the gradual clinical implementation of FUS-induced BBB opening. Even though the safety profile of FUS treatments in rodents has been extensively studied, the histological and behavioral effects of clinically relevant BBB opening in large animals are relatively understudied. Here, we examine the histological and behavioral safety profile following localized BBB opening in non-human primates (NHPs), using a neuronavigation-guided clinical system prototype. We show that FUS treatment triggers a short-lived immune response within the targeted region without exacerbating the touch accuracy or reaction time in visual-motor cognitive tasks. Our experiments were designed using a multiple-case-study approach, in order to maximize the acquired data and support translation of the FUS system into human studies. Four NHPs underwent a single session of FUS-mediated BBB opening in the prefrontal cortex. Two NHPs were treated bilaterally at different pressures, sacrificed on day 2 and 18 post-FUS, respectively, and their brains were histologically processed. In separate experiments, two NHPs that were earlier trained in a behavioral task were exposed to FUS unilaterally, and their performance was tracked for at least 3 weeks after BBB opening. An increased microglia density around blood vessels was detected on day 2, but was resolved by day 18. We also detected signs of enhanced immature neuron presence within areas that underwent BBB opening, compared to regions with an intact BBB, confirming previous rodent studies. Logistic regression analysis showed that the NHP cognitive performance did not deteriorate following BBB opening. These preliminary results demonstrate that neuronavigation-guided FUS with a single-element transducer is a non-invasive method capable of reversibly opening the BBB, without substantial histological or behavioral impact in an animal model closely resembling humans. Future work should confirm the observations of this multiple-case-study work across animals, species and tasks.

We present real-time cavitation monitoring and mapping in a clinical trial for blood-brain barrier (BBB) opening in Alzheimer’s disease (AD) patients using a neuronavigation-guided focused ultrasound (FUS) system. Six AD patients (N = 6, age = 68.5 ± 9.5) were sonicated at the right prefrontal lobe with a single-element FUS transducer (PNP = 0.2 MPa, fc = 0.25 MHz, pulse length = 10 ms, PRF = 2 Hz, duration = 2 min) with the microbubble administration (Definity). We performed passive cavitation detection (PCD) using a single-element hydrophone (N = 4), and passive acoustic mapping (PAM) with a 64-element phased array transducer (N = 2). Five patients showed successful BBB opening (volume = 654 ± 394 mm3) on day0, and closure on day3, confirmed by contrast-enhanced T1-weighted MRI, while one patient served as a negative BBB opening case due to the insufficient microbubble administration. Ultra-harmonic cavitation dose (CD) correlated with the opening volume (R2 = 0.66, N = 4), but harmonic and broadband CDs showed a relatively poor correlation (R2 = 0.06 and 0.33). Cavitation maps (N = 2) showed a spatial distribution of acoustic energy that roughly coincided with the respective BBB opening location. We thus demonstrated the successful BBB opening and cavitation monitoring with the neuronavigation-guided system that allowed for a cost-effective procedure compared to the MR-guided approaches. The PCD and PAM showed promising results for potentially predicting the BBB opening volume and location found in MRI.

Focused ultrasound (FUS) for blood-brain barrier (BBB) opening is a safe, reversible and non-invasive strategy for targeted drug delivery to the brain, however extensive pre-planning strategies are necessary for successful FUS-mediated BBB opening through the structurally complex primate skull. OBJECTIVE: This work aims to demonstrate a pre-planning pipeline consisting of transcranial simulations and in vitro experimentation used to inform synchronous BBB opening and power cavitation imaging (PCI) with a single theranostic ultrasound (TUS) phased array. METHODS: Acoustic wave propagation simulation readouts of pressure attenuation and focal shift through clinical-CT and micro-CT-based primate skull models were compared, while the latter were used to determine the impact of beam steering angle on focal shift and pressure attenuation. In vitro experimentation with a channel phantom enabled characterization of skull-induced receive focal shift (RFS), while in vivo BBB opening and PCI using in silico and in vitro pre-planning information was conducted using a custom Verasonics/MATLAB script. RESULTS: Simulations confirmed steering angle dependent transcranial focal shift and pressure attenuation, while in vitro experiments revealed minimal (0.30–1.50 mm) skull-induced RFS. In vivo rodent experiments with overlaid primate skull fragments demonstrated successful TUS-mediated BBB opening and spatially correlated power cavitation images (PCI) with regions of BBB opening on T(1)-weighted magnetic resonance images (MRI). CONCLUSION: Herein, we demonstrate the feasibility for TUS-mediated BBB opening in vivo using in silico and in vitro pre-planning information. SIGNIFICANCE: TUS as an ultrasound-guided modality for BBB opening could be a promising alternative to current FUS-mediated BBB opening configurations in the clinic.

Focused ultrasound-enhanced intranasal (IN + FUS) delivery is a noninvasive approach that utilizes the olfactory pathway to administer pharmacological agents directly to the brain, allowing for a more homogenous distribution in targeted locations compared to IN delivery alone. However, whether such a strategy has therapeutic values, especially in neurodegenerative disorders such as Parkinson’s disease (PD), remains to be established. Herein, we evaluated whether the expression of tyrosine hydroxylase (TH), the rate limiting enzyme in dopamine catalysis, could be enhanced by IN + FUS delivery of brain-derived neurotrophic factor (BDNF) in a toxin-based PD mouse model. Mice were put on the subacute dosing regimen of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), producing bilateral degeneration of the nigrostriatal pathway consistent with early-stage PD. MPTP mice then received BDNF intranasally followed by multiple unilateral FUS-induced blood-brain barrier (BBB) openings in the left basal ganglia for three consecutive weeks. Subsequently, mice were survived for two months and were evaluated morphologically and behaviorally to determine the integrity of their nigrostriatal dopaminergic pathways. Mice receiving IN + FUS had significantly increased TH immunoreactivity in the treated hemisphere compared to the untreated hemisphere while mice receiving only FUS-induced BBB opening or no treatment at all did not show any differences. Additionally, behavioral changes were only observed in the IN + FUS treated mice, indicating improved motor control function in the treated hemisphere. These findings demonstrate the robustness of the method and potential of IN + FUS for the delivery of bioactive factors for treatment of neurodegenerative disorder.

Theranostic Ultrasound (TUS) is a novel modality for combined blood-brain barrier (BBB) opening and cavitation mapping within a single multielement imaging transducer. While previous work developing TUS has focused on understanding qualitative spatial agreement of a cavitation mapping strategy called power cavitation imaging with regions of BBB opening indicated on contrast-enhanced magnetic resonance images (MRI), the impact of short pulse lengths on signal intensity of power cavitation images has yet to be resolved. In this study we evaluated the impact of short pulse lengths on BBB opening volume, power cavitation imaging signal intensity, and BBB closure with a novel rapid beam steering protocol, enabling comparison of TUS parameters within the same animal. Significant increases in BBB opening volume, power cavitation image signal intensity and BBB closing duration were observed with pulse length. Given the faster BBB closing rate facilitated by short pulse transmits, along with the highly tunable nature of TUS sonication protocols, TUS could prove promising as an alternative to conventional focused ultrasound (FUS) configurations in the clinic.

Focused Ultrasound (FUS) paired with systemically-introduced microbubbles (MB) is a widely-used noninvasive technique for transiently opening the Blood-Brain Barrier (BBB). FUS-BBBO is implicated in the treatment of several age-associated neuropathological disorders. The prevalence of these diseases in aged populations necessitates an investigation into and an understanding of the effect of age on the brain's response to FUS-BBBO. Here we show that advanced natural aging increases the brain's susceptibility to FUS-BBBO by increasing the volume of BBBO in response to equivalent sonication parameters. Additionally, the BBBO volume correlates positively with cavitation dose (CD). However, the extent of BBBO in response to cavitation is greater in two- compared to one-year old mice. Taken together, these results indicate an increased sensitivity in aged compared to younger mice, highlighting an important consideration in therapeutic planning.

The neuropathological hallmarks of Alzheimer's disease include amyloid plaques and neurofibrillary tangles. Tau pathology correlates well with impaired neuronal activity and dementia. Focused ultrasound coupled with systemic administration of microbubbles has previously been shown to open the blood-brain barrier and induce an immune response, which, in an amyloid AD mouse model, resulted in the reduction of the amyloid brain load. Methods: In this study, we investigated the effect of focused ultrasound at the early stages of tau pathology (pre-tangle) in the rTg4510 mouse model. Results: Reduction of phosphorylated tau from the hippocampal formation processes, and particularly the pyramidal CA1 neurons, was noted in the ultrasound-treated brains without an associated increase in the phosphorylated tau-affected cell somas, typically associated with disease progression. Attenuation of the pathology was found to correlate well with the ultrasound-initiated immune response without compromising neuronal integrity. Unilateral ultrasound application resulted in a bilateral effect indicating a broader reduction of the phosphorylated tau. Conclusion: Findings presented herein reinforce the premise of ultrasound in reducing tau pathology and thus curbing the progression of Alzheimer's disease.

Typically, focused ultrasound (FUS)- mediated blood-brain barrier (BBB) opening requires multiple components that include the therapeutic transducer itself and a separate monitoring technique. Combining the therapeutic transducer and monitoring technique into a single transducer has yet to be shown. In this study, we investigated the use a single diagnostic array for both FUS-mediated BBB opening and cavitation monitoring. Our phantom experiments confirm that using a standard diagnostic transducer, power cavitation images were able to be acquired during focus transmits. These power cavitation images were able to estimate the size of the focus in the imaging plane, which match well with the measurements taken with a hydrophone. Furthermore, in vivo experiments in mice and non-human primates were performed, with successful transcranial BBB opening and cavitation monitoring in both animal models. BBB opening were confirmed using contrast-enhanced magnetic resonance imaging, which correlated well with the corresponding power cavitation maps showing high cavitation activity.

Optimization of regenerative medicine strategies includes the design of biomaterials, development of cell-seeding methods, and control of cell-biomaterial interactions within the engineered tissues. Among these steps, one paramount challenge is to non-destructively image the engineered tissues in their entirety to assess structure, function, and molecular expression. It is especially important to be able to enable cell phenotyping and monitor the distribution and migration of cells throughout the bulk scaffold. Advanced fluorescence microscopic techniques are commonly employed to perform such tasks; however, they are limited to superficial examination of tissue constructs. Therefore, the field of tissue engineering and regenerative medicine would greatly benefit from the development of molecular imaging techniques which are capable of non-destructive imaging of three-dimensional cellular distribution and maturation within a tissue-engineered scaffold beyond the limited depth of current microscopic techniques. In this review, we focus on an emerging depth-resolved optical mesoscopic imaging technique, termed Laminar Optical Tomography (LOT) or Mesoscopic Fluorescence Molecular Tomography (MFMT), which enables longitudinal imaging of cellular distribution in thick tissue engineering constructs at depths of a few millimeters and with relatively high resolution. The physical principle, image formation, and instrumentation of LOT/MFMT systems are introduced. Representative applications in tissue engineering include imaging the distribution of human mesenchymal stem cells (hMSCs) embedded in hydrogels, imaging of bio-printed tissues, and in vivo applications.

Focused ultrasound enhanced intranasal (IN+FUS) delivery is a unique, noninvasive approach that utilizes the olfactory pathway to administer drugs directly to the brain. Our group has shown that IN+FUS delivery of model drugs provide a more homogenous distribution of delivery when compared to IN delivery alone, and similar delivery efficiency to intravenous delivery after FUS induced BBB opening. The aim of this study was to investigate the delivery efficacy and therapeutic effects that IN+FUS administered brain-derived neurotrophic factor (BDNF) has on an early-stage Parkinsonian mouse model in order to provide an alternate and more direct administration route to the brain. Wild-type mice were given a sub-acute dose of the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) toxin daily for 5 days, causing bilateral degeneration of the nigrostriatal dopaminergic pathway. After a stabilizing period, the mice were split into a treated group and a control group (N=7 /group). The treated group was dosed with IN+FUS of BDNF weekly for 3 weeks. Each week, 0.4 mg of BDNF was intranasally delivered followed by BBB opening in the left substantia nigra (SN) and caudate putamen (CP) using FUS and sized isolated microbubbles. The mice were then survived for 2 months to allow for any neurorestorative effects to occur. Behavioral testing through amphetamine-induced rotations was then conducted. Staining of tyrosine hydroxylase positive (TH+) neurons in the SN and terminals in the CP were used to assess the nigrostriatal dopaminergic pathway integrity. TH+ staining in the SN and CP indicated moderate neuronal survival in the ipsilateral side in treated mice while staining in untreated mice was similar bilaterally. Significant ipsilateral rotation in treated mice corroborated the immunohistochemistry findings, further validating improved ipsilateral nigrostriatal dopaminergic pathway. These findings indicate a modest neurorestorative effect of IN+FUS BDNF on MPTP mice, demonstrating the potential of an alternative and efficient drug delivery route for brain treatment with FUS. Additional immunohistochemistry assays and quantification in the SN and CP are ongoing to confirm these initial findings.

Focused ultrasound enhanced intranasal drug delivery (IN+FUS) is a unique noninvasive approach that utilizes the olfactory pathway to administer drugs directly to the brain. Our group has shown that IN+FUS provides a more homogenous distribution of molecules in the targeted region than intranasal delivery alone. The underlying mechanism of IN+FUS is believed to be due to the microbubble pump effect, where microbubble cavitation causes expansion and contraction of the perivascular space. Therefore, the aim of this study is to investigate a potential cavitation threshold that is required for successful IN+FUS.

Progress in bio-printing techniques has accentuated the need for non-invasive imaging modalities with high sensitivity, high resolution, and imaging depth of a few millimeters. Mesoscopic Fluorescence Molecular Tomography (MFMT) is a promising imaging modality for 3D localization and quantification of fluorescent labeled cells in thick scaffolds. Here we report on the characterization of our second generation MFMT system which uses an Electron-Multiplying charge coupled device (EMCCD). More precisely, we report on the effects of EM gain and deep cooling of the camera on signal-to-noise ratio (SNR) and hence the sensitivity. Experimental results showed that these parameters, when used in conjunction, increased SNR by at least 3 fold.