The effects of SENSE on PROPELLER imaging.

PURPOSE: To study how sensitivity encoding (SENSE) impacts periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) image quality, including signal-to-noise ratio (SNR), robustness to motion, precision of motion estimation, and image quality. METHODS: Five volunteers were imaged by three sets of scans. A rapid method for generating the g-factor map was proposed and validated via Monte Carlo simulations. Sensitivity maps were extrapolated to increase the area over which SENSE can be performed and therefore enhance the robustness to head motion. The precision of motion estimation of PROPELLER blades that are unfolded with these sensitivity maps was investigated. An interleaved R-factor PROPELLER sequence was used to acquire data with similar amounts of motion with and without SENSE acceleration. Two neuroradiologists independently and blindly compared 214 image pairs. RESULTS: The proposed method of g-factor calculation was similar to that provided by the Monte Carlo methods. Extrapolation and rotation of the sensitivity maps allowed for continued robustness of SENSE unfolding in the presence of motion. SENSE-widened blades improved the precision of rotation and translation estimation. PROPELLER images with a SENSE factor of 3 outperformed the traditional PROPELLER images when reconstructing the same number of blades. CONCLUSION: SENSE not only accelerates PROPELLER but can also improve robustness and precision of head motion correction, which improves overall image quality even when SNR is lost due to acceleration. The reduction of SNR, as a penalty of acceleration, is characterized by the proposed g-factor method.

Revised motion estimation algorithm for PROPELLER MRI.

PURPOSE: To introduce a new algorithm for estimating data shifts (used for both rotation and translation estimates) for motion-corrected PROPELLER MRI. The method estimates shifts for all blades jointly, emphasizing blade-pair correlations that are both strong and more robust to noise. THEORY AND METHODS: The heads of three volunteers were scanned using a PROPELLER acquisition while they exhibited various amounts of motion. All data were reconstructed twice, using motion estimates from the original and new algorithm. Two radiologists independently and blindly compared 216 image pairs from these scans, ranking the left image as substantially better or worse than, slightly better or worse than, or equivalent to the right image. RESULTS: In the aggregate of 432 scores, the new method was judged substantially better than the old method 11 times, and was never judged substantially worse. CONCLUSION: The new algorithm compared favorably with the old in its ability to estimate bulk motion in a limited study of volunteer motion. A larger study of patients is planned for future work.

Imaging of Adult Malignant Soft Tissue Tumors of the Spinal Canal: A Guide for Spine Surgeons.

BACKGROUND: Malignant soft tissue spinal canal tumors compromise 20% of all spinal neoplasms. They may be primary or metastatic lesions, originating from a diverse range of tissues within and surrounding the spinal canal. These masses can present as diverse emergencies such as secondary cauda equina syndrome, vascular compromise, or syringomyelia. Interpretation of malignant soft tissue spinal canal tumors imaging is an essential for non-radiologists in the setting of emergencies. This task is intricate due to a great radiologic pattern overlap among entities. METHODS: We present a step-by-step strategy that can guide nonradiologists identify a likely malignant soft tissue lesion in the spinal canal based on imaging features, as well as a review of the radiologic features of malignant soft tissue spinal canal tumors. RESULTS: Diagnosis of soft tissue spinal canal malignancies starts with the identification of the lesion's spinal level and its relationship to the dura and medulla. The second step consists of characterizing it as likely-malignant based on radiological signs like a larger size, ill-defined margins, central necrosis, and/or increased vascularity. The third step is to identify additional imaging features such as intratumoral hemorrhage or cyst formation that can suggest specific malignancies. The physician can then formulate a differential diagnosis. The most encountered malignant soft tissue tumors of the spinal canal are anaplastic ependymomas, anaplastic astrocytomas, metastatic tumors, lymphoma, peripheral nerve sheath tumors, and central nervous system melanomas. A review of the imaging features of every type/subtype of lesion is presented in this work. Although magnetic resonance imaging remains the modality of choice for spinal tumor assessment, other techniques such as dynamic contrast agent-enhanced perfusion magnetic resonance imaging or diffusion-weighted imaging could guide diagnosis in specific situations. CONCLUSIONS: In this review, diagnostic strategies for several spinal cord tumors were presented, including anaplastic ependymoma, metastatic spinal cord tumors, anaplastic and malignant astrocytoma, lymphoma, malignant peripheral nerve sheath tumors , and primary central nervous system melanoma. Although the characterization of spinal cord tumors can be challenging, comprehensive knowledge of imaging features can help overcome these challenges and ensure optimal management of spinal canal lesions.

Management Algorithm for Osseous Metastatic Disease: What the Treatment Teams Want to Know.

Radiologists play a primary role in identifying, characterizing, and classifying spinal metastases and can play a lifesaving role in the care of these patients by triaging those with instability to urgent spine surgery consultation. For this reason, an understanding of current treatment algorithms and principles of spinal stability in patients with cancer is vital for all who interpret spine studies. In addition, advances in imaging allow radiologists to provide more accurate diagnoses and characterize pathology, thereby improving patient safety.

Multispecialty perspective on intradural disc herniation: diagnosis and management - A case report.

BACKGROUND: Intradural disc herniation (IDH) is a very rare and challenging diagnosis, with an estimated incidence of less than 1.5%. The pathogenesis of IDH remains uncertain. Definitive management remains surgical; however, some cases may initially be managed non-surgically. CASE: A middle-aged male with presented with acute right-sided lumbar radiculopathy following heavy lifting. History was significant for prior lumbar disc herniation managed non-surgically. Lumbar MRI demonstrated a large disc herniation. The patient was initially treated non-surgically with epidural steroid injections. At 4-months, he re-injured and follow-up images demonstrated the herniated disc penetrating the dura and the diagnosis of intradural disc herniation. CONCLUSIONS: The present case is rare because the IDH occurred at the L3-4 level and resulted in unilateral radiculopathy without cauda-equina symptoms and occurred in the absence of prior surgery. This patient was initially treated non-surgically with satisfactory relief, however, reinjury led to progression of IDH with new neurological deficits necessitating surgery.

Utility of Virtual Spine Neurosurgery Education for Medical Students.

OBJECTIVE: Distance learning has become increasingly important to expand access to neurosurgical spine education. However, emerging online spine education initiatives have largely focused on residents, fellows, and surgeons in practice. We aimed to assess the utility of online neurosurgical spine education for medical students regarding career interests, knowledge, and technical skills. METHODS: A survey assessing the demographics and effects of virtual spine education programming on the interests, knowledge, and technical skills was sent to attendees of several virtual spine lectures. The ratings were quantified using 7-point Likert scales. RESULTS: A total of 36 responses were obtained, of which 15 (41.7%) were from first- or second-year medical students and 18 (50.0%) were from international students. Most respondents were interested in neurosurgery (n = 30; 80.3%), with smaller numbers interested in radiology (n = 3; 8.3%) and orthopedic surgery (n = 2; 5.6%). The rating of utility ranged from 5.69 ± 1.14 to 6.50 ± 0.81 for career, 5.83 ± 0.94 to 6.14 ± 0.80 for knowledge, and 5.22 ± 1.31 to 5.83 ± 1.06 for clinical skills. Of the 36 respondents, 26 (72.2%) preferred virtual neurosurgical spine education via intermixed lectures and interactive sessions. The most common themes regarding the utility of virtual spine education were radiology by 18 (50.0%), anatomy by 12 (33.3%), and case-based teaching by 8 (22.2%) respondents. CONCLUSIONS: Virtual distance learning for neurosurgical spine education is beneficial for students by enabling career exploration and learning content and clinical skills. Although the overall benefit was lowest for clinical skills, virtual programming could serve as an adjunct to traditional in-person exposure. Distance learning could also provide an avenue to reduce disparities in medical student neurosurgical spine education locally and globally.

Artificial Intelligence and Robotics in Spine Surgery.

STUDY DESIGN: Narrative review. OBJECTIVES: Artificial intelligence (AI) and machine learning (ML) have emerged as disruptive technologies with the potential to drastically affect clinical decision making in spine surgery. AI can enhance the delivery of spine care in several arenas: (1) preoperative patient workup, patient selection, and outcome prediction; (2) quality and reproducibility of spine research; (3) perioperative surgical assistance and data tracking optimization; and (4) intraoperative surgical performance. The purpose of this narrative review is to concisely assemble, analyze, and discuss current trends and applications of AI and ML in conventional and robotic-assisted spine surgery. METHODS: We conducted a comprehensive PubMed search of peer-reviewed articles that were published between 2006 and 2019 examining AI, ML, and robotics in spine surgery. Key findings were then compiled and summarized in this review. RESULTS: The majority of the published AI literature in spine surgery has focused on predictive analytics and supervised image recognition for radiographic diagnosis. Several investigators have studied the use of AI/ML in the perioperative setting in small patient cohorts; pivotal trials are still pending. CONCLUSIONS: Artificial intelligence has tremendous potential in revolutionizing comprehensive spine care. Evidence-based, predictive analytics can help surgeons improve preoperative patient selection, surgical indications, and individualized postoperative care. Robotic-assisted surgery, while still in early stages of development, has the potential to reduce surgeon fatigue and improve technical precision.

Virtual Spine: A Novel, International Teleconferencing Program Developed to Increase the Accessibility of Spine Education During the COVID-19 Pandemic.

BACKGROUND: The coronavirus identified in 2019 (COVID-19) pandemic effectively ended all major spine educational conferences in the first half of 2020. In response, the authors formed a "virtual" case-based conference series directed at delivering spine education to health care providers around the world. We herein share the technical logistics, early participant feedback, and future direction of this initiative. METHODS: The Virtual Global Spine Conference (VGSC) was created in April 2020 by a multiinstitutional team of spinal neurosurgeons and a neuroradiologist. Biweekly virtual meetings were established wherein invited national and international spine care providers would deliver case-based presentations on spine and spine surgery-related conditions via teleconferencing. Promotion was coordinated through social media platforms such as Twitter. RESULTS: VGSC recruited more than 1000 surgeons, trainees, and other specialists, with 50-100 new registrants per week thereafter. An early survey to the participants, with 168 responders, indicated that 92% viewed the content as highly valuable to their practice and 94% would continue participating post COVID-19. Participants from the United States (29%), Middle East (16%), and Europe (12%) comprised the majority of the audience. Approximately 52% were neurosurgeons, 18% orthopedic surgeons, and 6% neuroradiologists. A majority of participants were physicians (55%) and residents/fellows (21%). CONCLUSIONS: The early success of the VGSC reflects a strong interest in spine education despite the COVID-19 pandemic and social distancing guidelines. There is widespread opinion, backed by our own survey results, that many clinicians and trainees want to see "virtual" education continue post COVID-19.

Spine Oncology: Imaging and Intervention.

Osseous metastases are the most common spine tumor and increasingly prevalent as advances in cancer treatments allow patients to live longer with their disease. Evidence-based algorithms derive the majority of their data from imaging studies and reports; the radiologist should understand the most current treatments and report in the language of the treatment team for efficient and effective communication and patient care. Advanced imaging techniques such as diffusion-weighted imaging and dynamic contrast-enhanced MRI are increasingly used for diagnosis and problem solving. Radiologists have a growing role in treatment of patients with metastatic disease, performing cement augmentation and tumor ablation.

Headache and Brain Tumor.

Headaches are exceedingly common, but most individuals who seek medical attention with headache will not have a serious underlying etiology such as a brain tumor. Brain tumors are uncommon; however, many patients with brain tumors do suffer from headaches. Generally these headaches are accompanied by other neurologic signs and symptoms. A careful clinical assessment for red flags should be undertaken when considering further work-up with neuroimaging to exclude a serious underlying condition.

Conventional and Advanced Imaging of Spine Oncologic Disease, Nonoperative Post-treatment Effects, and Unique Spinal Conditions.

In this review, we discuss the imaging features of diseases and conditions ranging from neoplastic to nonoperative post-treatment effects to unique conditions of the spine. Additionally, advanced imaging may increase diagnostic certainty in cases where conventional imaging characteristics of benign lesions and malignant pathology are variable.

Acute hemorrhagic leukoencephalitis: neuroimaging features and neuropathologic diagnosis.

A case of biopsy-proven acute hemorrhagic leukoencephalitis is reported. The early computed tomography scans showed extensive bilateral hypodensities with mass effects and foci of microhemorrhages. Bilateral asymmetric hyperintensities in the mesiotemporal and frontal lobes and massive edema were found on T2-weighted and fluid-attenuated inversion recovery magnetic resonance images in a pattern classic for herpes simplex encephalitis. This fulminant demyelinating disease progresses to coma and death within days. Early diagnosis with neuroimaging studies and rapid correlation with the clinical findings of this disease are vital for the institution of potentially lifesaving treatments.