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Traumatic spinal cord injury (SCI) is a common and devastating condition. In the absence of effective validated therapies, there is an urgent need for novel methods to achieve injury stabilization, regeneration, and functional restoration in SCI patients. Ultrasound is a versatile platform technology that can provide a foundation for viable diagnostic and therapeutic interventions in SCI. In particular, real-time perfusion and inflammatory biomarker monitoring, focal pharmaceutical delivery, and neuromodulation are capabilities that can be harnessed to advance our knowledge of SCI pathophysiology and to develop novel management and treatment options. Our review suggests that studies that evaluate the benefits and risks of ultrasound in SCI are severely lacking and our understanding of the technology's potential impact remains poorly understood. Although the complex anatomy and physiology of the spine and the spinal cord remain significant challenges, continued technological advances will help the field overcome the current barriers and bring ultrasound to the forefront of SCI research and development.

Cotton balls are used in neurosurgical procedures to assist with hemostasis and improve vision within the operative field. Although the surgeon can reshape pieces of cotton for multiple intraoperative uses, this customizability and scale also places them at perpetual risk of being lost, as blood-soaked cotton balls are visually similar to raw brain tissue. Retained surgical cotton can induce potentially life-threatening immunologic responses, impair postoperative imaging, lead to a textiloma or misdiagnosis, and/or require reoperation. This study investigated three imaging modalities (optical, acoustic, and radiographic) to find the most effective method of identifying foreign bodies during neurosurgery. First, we examined the use of dyes to increase contrast between cotton and surrounding parenchyma (optical approach). Second, we explored the ability to distinguish surgical cotton on or below the tissue surface from brain parenchyma using ultrasound imaging (acoustic approach). Lastly, we analyzed the ability of radiography to differentiate between brain parenchyma and cotton. Our preliminary testing demonstrated that dark-colored cotton is significantly more identifiable than white cotton on the surface level. Additional testing revealed that cotton has noticeable different acoustic characteristics (eg, speed of sound, absorption) from neural tissue, allowing for enhanced contrast in applied ultrasound imaging. Radiography, however, did not present sufficient contrast, demanding further examination. These solutions have the potential to significantly reduce the possibility of intraoperative cotton retention both on and below the surface of the brain, while still providing surgeons with traditional cotton material properties without affecting the surgical workflow.

Total hip arthroplasty (THA) procedures have been identified as high-volume procedures with growing prevalence. During the procedure, orthopedic surgeons largely rely solely on qualitative assessment to ensure an excessive limb length discrepancy (LLD) is not introduced from the implant selection. LLD can result in back pain and gait complications, with some cases of LLD requiring a revision procedure to mitigate. To address this issue, we evaluated several methods of sensing distance intraoperatively to determine the best approach to measure leg length during the THA procedure. A testing setup using a sawbones model of hip anatomy in the decubitus position was used as a simulation of the THA procedure to test the accuracy of each of the sensing modalities.

Many surgeons are faced with inoperable or only partially operable brain lesions, such as tumors. Even when surgery is feasible, patient outcomes are greatly affected by blood loss or infection. This has led many physicians toward non- or minimally-invasive surgery, which demands specialized toolkits. Focused ultrasound has great potential for assisting in such procedures due to its ability to focus a few centimeters away from the surface of the transducer. In a prior study, we developed a focused ultrasound prototype that could fit within a BrainPath trocar, specifically made for minimally invasive brain surgery. Here, we present the design and fabrication of a second prototype that reduces size, is MR-compatible, and has electronic steering capabilities.

Access to deep-seated brain lesions (e.g., tumors, aneurysms, hematomas, and other malformations) is challenging due to the potential for retraction-induced injury. Traditionally, neurosurgeons use dissection and blade retractors to push apart tissue to visualize and operate on target lesions. These blades apply focal pressure onto the brain, resulting in ischemia, edema, and parenchymal trauma, leading to complications in up to 29% of cases. Tubular retractors were introduced to distribute forces radially and have led to improved safety and clinical outcomes. However, reports indicate that tubular retractors still led to complications in up to 9.1% of cases. Other concerns include significant pressure in the direction of insertion and the displacement of anatomic landmarks leading to inaccurate stereotaxis. We present a novel, minimally-invasive brain retractor that utilizes an expandable soft balloon to further reduce retraction-induced injury and increase stereotactic accuracy with a minimal port of entry. The device consists of a balloon catheter system, a clear sheath, and integration with neuronavigation stylets. This approach can reduce the rate of iatrogenic injury and improve clinical outcomes for brain lesion operations. Furthermore, we illustrate the efficacy of this device in use compared to those of conventional tubular and blade retractors in a pig cadaver.

Cotton balls are a versatile and efficient tool commonly used in neurosurgical procedures to absorb fluids and manipulate delicate tissues. However, the use of cotton balls is accompanied by the risk of accidental retention in the brain after surgery. Retained cotton balls can lead to dangerous immune responses and potential complications, such as adhesions and textilomas. In a previous study, we showed that ultrasound can be safely used to detect cotton balls in the operating area due to the distinct acoustic properties of cotton compared with the acoustic properties of surrounding tissue. In this study, we enhance the experimental setup using a 3D-printed custom depth box and a Butterfly IQ handheld ultrasound probe. Cotton balls were placed in variety of positions to evaluate size and depth detectability limits. Recorded images were then analyzed using a novel algorithm that implements recently released YOLOv4, a state-of-the-art, real-time object recognition system. As per the radiologists’ opinion, the algorithm was able to detect the cotton ball correctly 61% of the time, at approximately 32 FPS. The algorithm could accurately detect cotton balls up to 5mm in diameter, which corresponds to the size of surgical balls used by neurosurgeons, making the algorithm a promising candidate for regular intraoperative use.

Colonoscopies are routine, low-risk procedures that are used to screen patients for diseases like colorectal cancer. However, often times they are performed with moderate sedation (i.e. conscious sedation) which may result in pain for patients. With moderate sedation, these procedures can be extremely painful, with one study reporting that more than 20% of patients experienced severe pain. This pain is usually the result of a phenomenon called “endoscopic looping,” which occurs when the scope loops within the patient’s bowels and stretches out their intestines. Looping is extremely common, and can occur in up to 90% of procedures. This study reports a low-cost endoscopy visualization device aimed to decrease patient pain during colonoscopies and time lost due to complications experienced during procedures. The device consists of a flexible piezoelectric sensor to detect applied forces during looping, bending, or compression. In order to use the device, the endoscopist inserts the piezoelectric cable fully within the working channel of the colonoscope before the colonoscopy begins. The piezoelectric cable is connected to an external monitor. If extreme forces or bends are detected by the piezoelectric cable, a notification can appear on screen that a loop is forming. Once the colonoscope reaches the desired location, the endoscopist removes the piezoelectric cable, leaving the working channel open for use by other tools, such as biopsy forceps.

Postpartum hemorrhage (PPH) is the leading cause of maternal mortality worldwide, and effective interventions for addressing PPH are urgently needed. Uterine balloon tamponade (UBT) is a technique to control PPH. Commercially available UBT devices are expensive and frequently require imaging technology to ensure placement. Condom-catheter uterine tamponade (C-UBT) is a technique appropriate for low-resource settings. Testing of the C-UBT is needed to better understand and optimize this technique for use in a variety of clinical settings including low-resource contexts. We describe here the design, development, and bench-top validation of a reusable C-UBT device optimized for low-resource settings. The device was tested in three differently sized uterine models using a variety of condom balloon configurations. Intrauterine wall pressure application was measured to evaluate the device capacity to apply pressure of at least 90 mmHg, estimating the mean arterial pressure within the uterine vasculature. Bench-top experimental validation of pressure exerted in uterine models demonstrated the device's capability of reaching hemostatic pressure in uterine volumes ranging from 170 to 1740 mL. Device adaptability and versatility were shown through its ability to reach the target pressure of 90 mmHg in different uterine sizes by varying balloon parameters, including condom thickness and condom configuration. The results of this study show the potential of a low-cost, reusable C-UBT device optimized to treat PPH in a variety of clinical settings, including low-resource contexts.

Background Previously, sonographic evaluation of the intracranial contents was limited to intraoperative use following bone flap removal, with placement of the probe directly on the cortical surface or through a transsulcal tubular retractor. Cranioplasty with sonolucent implants may represent a postoperative window into the brain by allowing ultrasound to serve as a novel bedside imaging modality. The potential sonolucency of various commonly used cranial implant types was examined in this study. Methods A 3-phase study was comprised of cadaveric evaluation of transcranioplasty ultrasound (TCU) with cranioplasty implants of varying materials, intraoperative TCU during right-sided cranioplasty with clear implant made of poly-methyl-methacrylate (PMMA), and bedside TCU on postoperative day 5 after cranioplasty. Results The TCU through clear PMMA, polyether-ether-ketone, and opaque PMMA cranial implants revealed implant sonoluceny, in contrast to autologous bone and porous-polyethylene. Intraoperative ultrasound via the clear PMMA implant in a single patient revealed recognizable ventricular anatomy. Furthermore, postoperative bedside ultrasound in the same patient revealed comparable ventricular anatomy and a small epidural fluid collection corresponding to that visualized on an axial computed tomography scan. Conclusion Sonolucent cranial implants, such as those made of clear PMMA, hold great promise for enhanced diagnostic and therapeutic applications previously limited by cranial bone. Furthermore, as functional cranial implants are manufactured with implantable devices housed within clear PMMA, the possibility of utilizing ultrasound for real-time surveillance of intracranial pathology becomes much more feasible.

Cervical spondylosis may lead to spinal cord compression, poor vascular perfusion, and ultimately, cervical myelopathy. Studies suggest a neuroprotective effect of renin-angiotensin system (RAS) inhibitors in the brain, but limited data exist regarding their impact on the spinal cord.To investigate whether RAS blockers and other antihypertensive drugs are correlated with preoperative functional status and imaging markers of cord compression in patients with symptomatic cervical spondylosis.Retrospective observational study.Individuals with symptomatic degenerative cervical stenosis who underwent surgery.Imaging features of spinal cord compression and functional status (modified Japanese Orthopedic Association [mJOA] and Nurick grading scales).Two hundred sixty-six operative patients with symptomatic degenerative cervical stenosis were included. Demographic data, comorbidities, antihypertensive medications, and functional status (including mJOA and Nurick grading scales) were collected. We evaluated canal compromise, cord compromise, surface area of T2 signal cord change, and pixel intensity of signal cord change compared with normal cord on T2-weighted magnetic resonance imaging sequences.Of 266 patients, 41.7% were women, 58.3% were men; median age was 57.2 years; 20.6% smoked tobacco; 24.7% had diabetes mellitus. One hundred forty-nine patients (55.8%) had hypertension, 142 (95.3%) of these were taking antihypertensive medications (37 angiotensin-II receptor blockers [ARBs], 44 angiotensin-converting enzyme inhibitors, and 61 other medications). Patients treated with ARBs displayed a higher signal intensity ratio (ie, less signal intensity change in the compressed cord area) compared with untreated patients without hypertension (p=.004). Patients with hypertension had worse preoperative mJOA and Nurick scores than those without (p.001). In the multivariate analysis, ARBs remained an independent beneficial factor for lower signal intensity change (p=.04), whereas hypertension remained a risk factor for worse preoperative neurological status (p.01).In our study, patients with hypertension who were treated with RAS inhibitors had decreased T2-weighted signal intensity change than untreated patients without hypertension. Patients with hypertension also had worse preoperative functional status. Prospective case-control studies may deepen understanding of RAS modulators in the imaging and functional status of chronic spinal cord compression.

Neurosurgery typically requires craniectomy and meticulous dissection to achieve sufficient exposure for subsequent surgical intervention. This highly invasive process requires hours of operating time, long recovery periods and leaves patients with visible surgical scars. Non-invasive high-intensity focused ultrasound (HIFU) has shown some promise yet remains challenged by the attenuation of ultrasonic waves while passing through the skull. Consequently, the clinical impact of this technology remains limited, particularly in the treatment of neuro-oncology. In order to compensate for acoustic attenuation, excessive use of power for HIFU devices has been investigated, although it is undesirable from a regulatory and patient safety standpoint. Here, we report the design and development of a novel HIFU device prototype for neurologic lesion ablation. This device concept is envisioned to access the ventricular space via a minimally invasive ventriculostomy, allowing ultrasound to reach targets deep in the brain, while eliminating the need for high power to penetrate the skull.

Pathologic thrombosis kills more people than cancer and trauma combined; it is associated with significant disability and morbidity, and represents a major healthcare burden. Despite advancements in medical therapies and imaging, there is often incomplete resolution of the thrombus. The residual thrombus can undergo fibrotic changes over time through infiltration of fibroblasts from the surrounding tissues and eventually transform into a permanent clot often associated with post-thrombotic syndrome. In order to understand the importance of cellular interactions and the impact of potential therapeutics to treat thrombosis, an in vitro platform using human cells and blood components would be beneficial. Towards achieving this aim, there have been studies utilizing the capabilities of microdevices to study the hemodynamics associated with thrombosis. In this work, we further exploited the utilization of 3D bioprinting technology, for the construction of a highly biomimetic thrombosis-on-a-chip model. The model consisted of microchannels coated with a layer of confluent human endothelium embedded in a gelatin methacryloyl (GelMA) hydrogel, where human whole blood was infused and induced to form thrombi. Continuous perfusion with tissue plasmin activator led to dissolution of non-fibrotic clots, revealing clinical relevance of the model. Further encapsulating fibroblasts in the GelMA matrix demonstrated the potential migration of these cells into the clot and subsequent deposition of collagen type I over time, facilitating fibrosis remodeling that resembled the in vivo scenario. Our study suggests that in vitro 3D bioprinted blood coagulation models can be used to study the pathology of fibrosis, and particularly, in thrombosis. This versatile platform may be conveniently extended to other vascularized fibrotic disease models.

Percutaneous pelvic screw placement is challenging due to narrow bone corridors surrounded by vulnerable structures and difficult visual interpretation of complex anatomical shapes in 2D x-ray projection images. To address these challenges, a system for planning, guidance, and quality assurance (QA) is presented, providing functionality analogous to surgical navigation, but based on robust 3D-2D image registration techniques using fluoroscopy images already acquired in routine workflow. Two novel aspects of the system are investigated: automatic planning of pelvic screw trajectories and the ability to account for deformation of surgical devices (K-wire deflection). Atlas-based registration is used to calculate a patient-specific plan of screw trajectories in preoperative CT. 3D-2D registration aligns the patient to CT within the projective geometry of intraoperative fluoroscopy. Deformable known-component registration (dKC-Reg) localizes the surgical device, and the combination of plan and device location is used to provide guidance and QA. A leave-one-out analysis evaluated the accuracy of automatic planning, and a cadaver experiment compared the accuracy of dKC-Reg to rigid approaches (e.g., optical tracking). Surgical plans conformed within the bone cortex by 3–4 mm for the narrowest corridor (superior pubic ramus) and >5 mm for the widest corridor (tear drop). The dKC-Reg algorithm localized the K-wire tip within 1.1 mm and 1.4° and was consistently more accurate than rigid-body tracking (errors up to 9 mm). The system was shown to automatically compute reliable screw trajectories and accurately localize deformed surgical devices (K-wires). Such capability could improve guidance and QA in orthopaedic surgery, where workflow is impeded by manual planning, conventional tool trackers add complexity and cost, rigid tool assumptions are often inaccurate, and qualitative interpretation of complex anatomy from 2D projections is prone to trial-and-error with extended fluoroscopy time.

BACKGROUND CONTEXT Cervical spondylosis may lead to spinal cord compression, poor vascular perfusion, and ultimately cervical myelopathy. The process whereby chronic compression may cause spinal cord damage has not been fully understood. However, multiple mechanisms such as inflammation, apoptosis, and vascular variations, are thought to be responsible for the neuronal loss, axonal degeneration, and myelin impairment seen in cervical spondylotic myelopathy (CSM). Studies reported a beneficial effect of renin-angiotensin system (RAS) blockers in the central nervous system, particularly in brain inflammation and stroke, but data on their influence on the spinal cord are limited. PURPOSE We aimed to determine if RAS blockers are correlated with preoperative functional status and radiological markers of spinal cord damage secondary to compression in patients with CSM. STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE Symptomatic cervical spondylosis patients. OUTCOME MEASURES Functional status (including modified Japanese Orthopedic Association [mJOA] and Nurick grading scales) and imaging characteristics (including % maximum canal compromise [MCC], % maximum spinal cord compromise [MSCC], increased signal intensity [ISI], signal intensity ration [SIR] and ISI surface area), all of which were evaluated on midsagittal T2-weighted MRIs. METHODS Adults with symptomatic degenerative cervical stenosis patients were included. Demographic data, comorbidities, antihypertensive medications (particularly RAS blockers), and functional status were collected. We assessed % canal compromise, % cord compromise, surface area of T2 signal cord change, and pixel intensity of signal cord change compared to normal cord on T2-weighted MRI sequences. RESULTS Of the 267 patients, 41.6% were female and 58.1% male; median age of 57.2 years; 20.6% smokers; 24.7% diabetics. One hundred forty-nine patients (55.8%) had hypertension, of which 142 (95.3%) were taking antihypertensive medications: 37 angiotensin-II receptor blockers [ARBs], 44 angiotensin-converting enzyme inhibitors [ACEIs], and 61 other medications). Patients treated with ARBs displayed a higher signal intensity ratio (lower signal intensity change in the compressed cord area) compared to those untreated non-hypertensive patients (p=.004). Hypertensive patients had worse preoperative mJOA and Nurick scores compared to non-hypertensive patients (p CONCLUSIONS In cervical spinal cord compression patients, hypertensive subjects treated with RAS inhibitors were associated with less signal intensity change (higher SIR) than untreated non-hypertensive patients. Also, hypertensive subjects under any antihypertensive medication displayed worse mJOA and Nurick scores compared to untreated non-hypertensive individuals. Further studies are warranted to verify the effect of RAS inhibitors in spinal cord damage. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

The work described in this book is based on the results of prior studies in our laboratory. Such studies suggested an optimal range of ultrasound frequency (1–3 MHz) for bone sonography, for the purpose of providing a guidance system for pedicle screw implant insertion during spinal fusion surgery.

Purpose The core needle biopsy (CNB) procedure is an essential part of breast cancer diagnosis. Current CNB devices on the market are not suitable for low-resource settings, which makes early breast cancer diagnosis inaccessible for women in these areas. Disposable CNB devices are the gold standard of breast cancer diagnostic tools in high-income countries, but the single-use cost—approximately $40 to $200—is unaffordable in low- and middle-income countries. Existing reusable devices are susceptible to internal contamination as blood travels back through the coaxial needle into the driver and thus requires laborious cleaning procedures. Methods After conducting more than 100 interviews with stakeholders at 18 hospitals in the United States, South Africa, and Peru, we devised criteria for the device. The device must prevent internal driver contamination and match the standard tissue sample size. We report the design and development of a reusable CNB device with disposable needles that trap contamination. To demonstrate where blood travels in current reusable devices and prove that internal contamination can be completely eliminated, we created an external attachment that interfaces with the Bard Magnum, an existing reusable driver that yields internal contamination. To prove our concept, we evaluated contamination rates by placing water-indicating tape inside the Bard driver and firing the device into a plastic test tube that was filled with blood-mimicking solutions and covered with a latex glove. Results When we fired the existing Bard Magnum device without our attachment, contaminants entered the internal compartment of the device both times, as shown by the water-indicating tape; however, when the device was fired with our external needle attachment, the water-indicating tape was completely clean, which verified that there was no internal contamination. Conclusion We can conclude from our contamination testing that blood enters the device as a result of contaminants traveling back between the faces of the needle and sheath into the device’s driver and that our external attachment eliminates this risk. Using these insights, we are currently developing a full reusable driver device with novel disposable needles that trap contamination to remove safety concerns associated with reusable devices, lower procedural cost, and increase access to breast cancer diagnostic tools in low-resource settings. AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST The following represents disclosure information provided by authors of this manuscript. All relationships are considered compensated. Relationships are self-held unless noted. I = Immediate Family Member, Inst = My Institution. Relationships may not relate to the subject matter of this manuscript. For more information about ASCO's conflict of interest policy, please refer to www.asco.org/rwc or ascopubs.org/jco/site/ifc . Megan Callanan Employment: Stryker Spine Patents, Royalties, Other Intellectual Property: Ithemba LLC Laura Hinson Patents, Royalties, Other Intellectual Property: Ithemba LLC Madeline Lee Patents, Royalties, Other Intellectual Property: Ithemba LLC Sophia Triantis Patents, Royalties, Other Intellectual Property: Ithemba LLC Amir Manbachi Research Funding: Siemens Healthineers (Inst) Susan Harvey Honoraria: Hologic Inc, IBM Watson Imaging Consulting or Advisory Role: IBM Watson, Hologic Inc Research Funding: IBM Watson

Background context In spinal fusion surgery, the accuracy with which screws are inserted in the pedicle has a direct effect on the surgical outcome. Accurate placement generally involves considerable judgmental skills that have been developed through a lengthy training process. Because the impact of misaligning one or more pedicle screws can directly affect patient safety, a number of navigational and trajectory verification approaches have been described and evaluated in the literature to provide some degree of guidance to the surgeon. Purpose To provide a concise review to justify the need and explore the current state of developing navigational or trajectory verification techniques for ensuring proper pedicle screw insertion along with simulation methods for better educating the surgical trainees. Study design Recent literature review. Methods To justify the need to develop new methods for optimizing pedicle screw paths, we first reviewed some of the recent publications relating to the statistical outcomes for different types of navigation along with the conventional freehand (unassisted) screw insertion. Second, because of the importance of providing improved training in the skill of accurate screw insertion, the training aspects of relevant techniques are considered. The third part is devoted to the description of specific navigational assist methods or trajectory verification techniques and these include computer-assisted navigation, three-dimensional simulations, and also electric impedance and optical and ultrasonic image-guided methods. Conclusions This article presents an overview of the need and the current status of the guidance methods available for improving the surgical outcomes in spinal fusion procedures. It also describes educational aids that have the potential for reducing the training process.

Clinical and engineering studies typically assume that the common carotid artery (CCA) is straight enough to assume fully developed flow, yet recent studies have demonstrated the presence of skewed velocity profiles. Towards elucidating the influence of mild vascular curvatures on blood flow patterns and atherosclerosis, the present study aimed to characterize the three-dimensional shape of the human CCA. The left and right carotid arteries of 28 participants (62±13 years) in the VALIDATE (Vascular Aging – The Link that Bridges Age to Atherosclerosis) study were digitally segmented from 3D contrast-enhanced magnetic resonance angiograms, from the aortic arch to the carotid bifurcation. Each CCA was divided into nominal cervical and thoracic segments, for which curvatures were estimated by least squares fitting of the respective centerlines to planar arcs. The cervical CCA had mean radius of curvature of 127 mm, corresponding to a mean lumen:curvature radius ratio of 1:50. The thoracic CCA was significantly more curved at 1:16, with the plane of curvature tilted by a mean angle of 25 degrees and rotated close to 90 degrees with respect to that of the cervical CCA. The left CCA was significantly longer and slightly more curved than the right CCA, and there was a weak but significant increase in CCA curvature with age. Computational fluid dynamic (CFD) simulations carried out for idealized CCA geometries derived from these and other measured geometric parameters demonstrated that mild cervical curvature is sufficient to prevent flow from fully developing, independent of the degree of thoracic curvature. These findings reinforce the idea that fully-developed flow may be the exception rather than the rule for the CCA, and perhaps other nominally long and straight vessels.