Cerebrospinal Fluid Leaks: Challenges in Localizing Spontaneous Spinal Leak Sites and Minimally Invasive Treatment.

The confirmation of cerebrospinal fluid (CSF) leaks in the setting of spontaneous intracranial hypotension (SIH) by imaging involves a growing toolset of multimodal advanced spinal and skull base imaging techniques, for which exists a unique set of challenges for each CSF leak type. Furthermore, the repertoire of minimally invasive CSF leak treatment beyond nontargeted epidural blood patch administration has grown widely, with varied practices across institutions. This review describes current diagnostic imaging and treatment modalities as they apply to the challenges of CSF leak localization and management.

Clinical utility of CT myelography renal collecting system density in the evaluation of spinal CSF leak or CSF-venous connection in patients with spontaneous intracranial hypotension.

INTRODUCTION: Identifying spontaneous CSF leaks can be difficult on CT myelography (CTM) in patients with suspected spontaneous intracranial hypotension (SIH). The current study compared renal collecting system (RCS) density during CTM in patients with suspected SIH relative to non-SIH controls and evaluated the overall utility as an indirect sign of spontaneous CSF leak in patients with SIH. METHODS: All CTM performed over an 8-year period (n = 392) were retrospectively reviewed and included cases (n = 295) were divided into groups consisting of SIH patients with (n = 35) or without (n = 77) confirmed CSF leak on CTM and non-SIH controls (n = 183). Average and relative average (relative to systemic contrast density) RCS densities were compared with multivariate analysis adjusting for patient characteristics and CTM technical differences. RESULTS: Average RCS densities were greater for confirmed versus non-confirmed SIH groups and greater for both SIH groups relative to non-SIH controls. Correlations between RCS density and time from injection to CTM were higher within SIH patient groups compared to controls. Measured RCS density had a higher negative predictive value for excluding CSF leak both within the SIH patient groups as well as the overall cohort (84% and 96%, respectively), with optimized thresholds yielding 80% sensitivity and 70% specificity for the presence of leak in the overall cohort. CONCLUSION: Accounting for RCS density may provide reliable additional indirect diagnostic value about the suspicion of a CSF leak in patients undergoing CTM for evaluation of SIH symptoms.

CT-based diagnosis in patients presenting with throat pain: A single institutional review.

RATIONALE AND OBJECTIVE: To determine if patient demographic data, medical history, physical examination, and laboratory tests will help predict likelihood of imaging-based diagnosis using CT of the neck performed in the ED for a chief complaint of throat pain. MATERIAL AND METHODS: Single institutional, retrospective review of 367 CT scans of the neck performed for the evaluation of throat pain in the ED from August 2013 to September 2019. Patients' clinical history, physical exams, lab findings, and imaging results were recorded. RESULTS: A total of 367 CT scans of the neck performed for the evaluation of throat pain included a recorded exam and clinical history. Of these cases, we noted that the presence of cervical lymphadenopathy (OR = 2.69; 95% CI, 1.37-5.49), tonsillar findings (OR = 2.94; 95% CI, 1.4-6.57), increased white blood cell count (OR = 1.08; 95% CI, 1.02-1.15), and temperature (OR = 1.94; 95% CI, 1.1-3.6) were associated with increased likelihood of obtaining a diagnostic CT scan. CONCLUSION: Consideration of tonsillar abnormalities, lymphadenopathy, body temperature, and measured leukocyte count prior to ordering CT scans of the neck for throat pain may increase the diagnostic yield of such exams and decrease CT utilization in the ED.

[68 Ga]-DOTATATE PET/MR-based evaluation of physiologic somatostatin receptor 2 expression in the adult pituitary gland as a function of age and sex in a prospective cohort.

PURPOSE: The pituitary gland has the fourth highest physiologic avidity of [68 Ga]-DOTATATE. In order to guide our understanding of [68 Ga]-DOTATATE PET in clinical contexts, accurate characterization of the normal pituitary gland is first required. This study aimed to characterize the normal pituitary gland using dedicated brain [68 Ga]-DOTATATE PET/MRI as a function of age and sex. METHODS: A total of 95 patients with a normal pituitary gland underwent brain [68 Ga]-DOTATATE PET examinations for the purpose of diagnosing CNS SSTR2 positive tumors (mean age: 58.9, 73% female). Maximum SUV of the pituitary gland was obtained in each patient. SUV of superior sagittal sinus was obtained to calculate normalized SUV score (SUVR) of the gland. The anatomic size of the gland was collected as maximum sagittal height (MSH). Correlations with age and sex were analyzed. RESULTS: The mean SUV and SUVR of the pituitary gland were 17.6 (range: 7-59.5, SD = 7.1) and 13.8 (range: 3.3-52.6, SD = 7.2), respectively. Older females had significantly higher SUV of the pituitary gland compared to younger females. When stratified by age and sex, both older and younger females had significantly higher pituitary SUV than older males. SUVR did not differ significantly by age or sex. MSH of the pituitary gland in younger females was significantly greater than in younger males at all age cutoffs. CONCLUSION: This study provides an empiric profiling of the physiological [68 Ga]-DOTATATE avidity of the pituitary gland. The findings suggest that SUV may vary by age and sex and can help guide the use of [68 Ga]-DOTATATE PET/MRI in clinical and research settings. Future studies can build on these findings to investigate further the relationship between pituitary biology and demographic factors.

Cranial MRgFUS intraprocedural diffusion and T2 imaging and comparison with postablation lesion size and location.

OBJECTIVE: The ability to predict final lesion characteristics during magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy for the treatment of essential tremor remains technically challenging, yet it is essential in order to avoid off-target ablation and to ensure adequate treatment. The authors sought to evaluate the technical feasibility and utility of intraprocedural diffusion-weighted imaging (DWI) in the prediction of final lesion size and location. METHODS: Lesion diameter and distance from the midline were measured on both intraprocedural and immediate postprocedural diffusion and T2-weighted sequences. Bland-Altman analysis was utilized to determine differences in measurement between intraprocedural and immediate postprocedural images with both sequences. RESULTS: Lesion size increased on both the postprocedural diffusion and T2-weighted sequences, although the difference was smaller on the T2-weighted sequence. There was only a small difference in intraprocedural and postprocedural lesion distance from the midline on both the diffusion and T2-weighted sequences. CONCLUSIONS: Intraprocedural DWI is both feasible and useful with regard to predicting final lesion size and providing an early indication of lesion location. Further research should determine the value of intraprocedural DWI in predicting delayed clinical outcomes.

Posterior hypothalamic involvement on pre-operative MRI predicts hypothalamic obesity in craniopharyngiomas.

PURPOSE: Hypothalamic obesity (HO) is a complication associated with craniopharyngioma (CP). Attempts have been made to perioperatively predict the development of this complication, which can be severe and difficult to treat. METHODS: Patients who underwent first transsphenoidal surgical resection in a single center between February 2005 and March 2019 were screened; those who have had prior surgery or radiation, were aged below 18 years, or did not have follow up body mass index (BMI) after surgery were excluded. Primary end point was BMI within 2 years post-surgery. Hypothalamic involvement (HI) was graded based on preoperative and postoperative imaging with regards to anterior, posterior, left and right involvement. Data on baseline demographics, pre-operative and post-operative MRI, and endocrine function were collected. RESULTS: 45 patients met the inclusion and exclusion criteria. Most patients in our cohort underwent gross total resection (n = 35 patients). 13 patients were from no HI or anterior HI only group and 22 patients were classified as both anterior (ant) and posterior (post) HI group. There was no significant difference between the two groups in the gross total, subtotal or near total resection. Pre-operative BMI and post-operative BMI were significantly higher in patients who had ant and post HI on pre-operative MRI (p < 0.05 and p < 0.01, respectively). Similarly, post-operative BMI at 13-24 months was also significantly higher in the ant and post HI group on post-op MRI (p < 0.01). There was no significant difference between the two groups in terms of baseline adrenal insufficiency, thyroid insufficiency, gonadal insufficiency, IGF-1 levels, hyperprolactinemia, and diabetes insipidus. Diabetes insipidus was more common following surgery among those who had anterior and posterior involvement on pre-operative MRI (p < 0.05). CONCLUSIONS: HO appears to be predetermined by tumor involvement in the posterior hypothalamus observed on pre-operative MRI. Posterior HI on pre-operative MRI was also associated with the development of diabetes insipidus after surgery.

Segmentation of Vestibular Schwannomas on Postoperative Gadolinium-Enhanced T1-Weighted and Noncontrast T2-Weighted Magnetic Resonance Imaging Using Deep Learning.

OBJECTIVE: Surveillance of postoperative vestibular schwannomas currently relies on manual segmentation and measurement of the tumor by content experts, which is both labor intensive and time consuming. We aimed to develop and validate deep learning models for automatic segmentation of postoperative vestibular schwannomas on gadolinium-enhanced T1-weighted magnetic resonance imaging (GdT1WI) and noncontrast high-resolution T2-weighted magnetic resonance imaging (HRT2WI). STUDY DESIGN: A supervised machine learning approach using a U-Net model was applied to segment magnetic resonance imaging images into pixels representing vestibular schwannoma and background pixels. SETTING: Tertiary care hospital. PATIENTS: Our retrospective data set consisted of 122 GdT1WI and 122 HRT2WI studies in 82 postoperative adult patients with a vestibular schwannoma treated with subtotal surgical resection between September 1, 2007, and April 17, 2018. Forty-nine percent of our cohort was female, the mean age at the time of surgery was 49.8 years, and the median time from surgery to follow-up scan was 2.26 years. INTERVENTIONS: N/A. MAIN OUTCOME MEASURES: Tumor areas were manually segmented in axial images and used as ground truth for training and evaluation of the model. We measured the Dice score of the predicted segmentation results in comparison to manual segmentations from experts to assess the model's accuracy. RESULTS: The GdT1WI model achieved a Dice score of 0.89, and the HRT2WI model achieved a Dice score of 0.85. CONCLUSION: We demonstrated that postoperative vestibular schwannomas can be accurately segmented on GdT1WI and HRT2WI without human intervention using deep learning. This artificial intelligence technology has the potential to improve the postoperative surveillance and management of patients with vestibular schwannomas.

Paramaxillary CT-guided fine needle aspiration of head and neck lesions: technique, diagnostic yield, and safety profile.

Computed tomography (CT)-guided percutaneous biopsy of deep-seated head and neck lesions can be a less invasive and equally effective alternative to surgical techniques. There are multiple approaches for needle biopsy that target varying spaces within the head and neck while successfully avoiding critical anatomy. In the paramaxillary approach, the needle is advanced through the infrazygomatic buccal space, in between the maxilla and mandible. In this study, we examine the safety and diagnostic yield of FNA without core needle biopsy performed via the paramaxillary approach in 19 patients yielding 20 fine needle aspirates between 2014 and 2022. Of the fine needle aspirates, 85.0% (17/20) were diagnostic. Concordant histopathologic diagnosis was obtained in 100% (17/17) diagnostic fine needle aspirates. There were no postprocedural complications.

Quantifying cerebrospinal fluid dynamics: A review of human neuroimaging contributions to CSF physiology and neurodegenerative disease.

Cerebrospinal fluid (CSF), predominantly produced in the ventricles and circulating throughout the brain and spinal cord, is a key protective mechanism of the central nervous system (CNS). Physical cushioning, nutrient delivery, metabolic waste, including protein clearance, are key functions of the CSF in humans. CSF volume and flow dynamics regulate intracranial pressure and are fundamental to diagnosing disorders including normal pressure hydrocephalus, intracranial hypotension, CSF leaks, and possibly Alzheimer's disease (AD). The ability of CSF to clear normal and pathological proteins, such as amyloid-beta (Aß), tau, alpha synuclein and others, implicates it production, circulation, and composition, in many neuropathologies. Several neuroimaging modalities have been developed to probe CSF fluid dynamics and better relate CSF volume and flow to anatomy and clinical conditions. Approaches include 2-photon microscopic techniques, MRI (tracer-based, gadolinium contrast, endogenous phase-contrast), and dynamic positron emission tomography (PET) using existing approved radiotracers. Here, we discuss CSF flow neuroimaging, from animal models to recent clinical-research advances, summarizing current endeavors to quantify and map CSF flow with implications towards pathophysiology, new biomarkers, and treatments of neurological diseases.

Decreased CSF clearance and increased brain amyloid in Alzheimer's disease.

BACKGROUND: In sporadic Alzheimer's disease (AD), brain amyloid-beta (Aß) deposition is believed to be a consequence of impaired Aß clearance, but this relationship is not well established in living humans. CSF clearance, a major feature of brain glymphatic clearance (BGC), has been shown to be abnormal in AD murine models. MRI phase contrast and intrathecally delivered contrast studies have reported reduced CSF flow in AD. Using PET and tau tracer 18F-THK5117, we previously reported that the ventricular CSF clearance of the PET tracer was reduced in AD and associated with elevated brain Aß levels. METHODS: In the present study, we use two PET tracers, 18F-THK5351 and 11C-PiB to estimate CSF clearance calculated from early dynamic PET frames in 9 normal controls and 15 AD participants. RESULTS: we observed that the ventricular CSF clearance measures were correlated (r = 0.66, p < 0.01), with reductions in AD of 18 and 27%, respectively. We also replicated a significant relationship between ventricular CSF clearance (18F-THK5351) and brain Aß load (r = - 0.64, n = 24, p < 0.01). With a larger sample size, we extended our observations to show that reduced CSF clearance is associated with reductions in cortical thickness and cognitive performance. CONCLUSIONS: Overall, the findings support the hypothesis that failed CSF clearance is a feature of AD that is related to Aß deposition and to the pathology of AD. Longitudinal studies are needed to determine whether failed CSF clearance is a predictor of progressive amyloidosis or its consequence.

[68Ga]-DOTATATE PET/MRI in the diagnosis and management of recurrent head and neck paraganglioma with spinal metastasis.

Most head and neck paragangliomas (PGLs) are biochemically silent and often present with recurrence and metastases in association with hereditary syndromes. Whole-body functional imaging is increasingly used to detect tumor extent and guide treatment planning of PGLs. [68Ga]-DOTATATE, which targets somatostatin receptor 2 (SSTR2) overexpression, has emerged as a sensitive functional imaging modality in PGLs. We present a patient with metastatic glomus caroticum PGL in whom [68Ga]-DOTATATE PET/MRI provided a more accurate characterization of metastatic extent, as compared to gadolinium-enhanced MRI of the neck and whole body [18F]-FDG PET/CT. We then review the current literature and discuss the imaging implications of [68Ga]-DOTATATE PET/MRI in PGLs.

Parathyroid Imaging: Four-dimensional Computed Tomography, Sestamibi, and Ultrasonography.

Primary hyperparathyroidism results most commonly from a parathyroid adenoma, a benign parathyroid tumor that causes high levels of parathyroid hormone production. Given recent advances in surgical techniques allowing more focused, minimally invasive procedures, presurgical identification of candidate operative tissue has become increasingly useful in avoidance of 4-gland exploration. Imaging modalities for identification of parathyroid adenoma include ultrasonography, parathyroid scintigraphy, four-dimensional computed tomography, and magnetic resonance imaging. This article discusses technical and interpretive approaches for the available modalities, and reviews their strengths and weaknesses. Updates to the individual modalities and approaches for problem solving in lesion detection are also addressed.

Cervical spinal cord infarction associated with coronavirus infectious disease (COVID)-19.

Coronavirus disease (COVID-19) has a number of emerging neurological manifestations in addition to pneumonia and respiratory distress. In what follows, we describe a case of a previously healthy young man with severe COVID-19 who subsequently developed an acute flaccid paralysis. Work up revealed a lesion in his cervical spinal cord concerning for spinal infarction or transverse myelitis. He received empiric pulsed steroids without improvement. Taken together, we felt his presentation was most consistent with spinal cord infarction in the setting of critical illness with COVID-19. We believe this is a rare case of spinal cord stroke associated with COVID-19.

[68Ga]-DOTATATE PET/CT and PET/MRI in the diagnosis and management of esthesioneuroblastoma: illustrative cases.

BACKGROUND: Esthesioneuroblastoma (ENB), also known as olfactory neuroblastoma, is a rare sinonasal neuroectodermal malignancy with a slow onset of symptoms, favorable 5-year survival, and a propensity for delayed locoregional recurrence. Current treatment options include resection, adjuvant radiotherapy, and/or chemotherapy; however, because of its rarity and location, determining the optimal treatment for ENB has been challenging. OBSERVATIONS: ENBs strongly express somatostatin receptors (SSTRs), particularly SSTR2, providing a molecular target for imaging and therapy. LESSONs: The authors present a case series of ENBs imaged with [68Ga]-DOTATATE PET/MRI and PET/CT and discuss the emerging role of [68Ga]-DOTATATE PET for ENB diagnosis, staging, and treatment response monitoring.

Imaging Glioblastoma Posttreatment: Progression, Pseudoprogression, Pseudoresponse, Radiation Necrosis.

Radiographic monitoring of posttreatment glioblastoma is important for clinical trials and determining next steps in management. Evaluation for tumor progression is confounded by the presence of treatment-related radiographic changes, making a definitive determination less straight-forward. The purpose of this article was to describe imaging tools available for assessing treatment response in glioblastoma, as well as to highlight the definitions, pathophysiology, and imaging features typical of true progression, pseudoprogression, pseudoresponse, and radiation necrosis.

Face-to-Face: Resident-led Radiology Medicine Rounds Facilitate Evidence-based Processes for Clinical Decision Support.

BACKGROUND: The transition toward value-based payment models increases focus on the radiologist's direct impact on hospital-provided patient care. Radiology trainees understand inpatient hospital workflows and decision-making paradigms and are well positioned to interface directly with hospital physicians regarding clinical decision making related to diagnostic imaging and/or image guided interventions. A radiology resident-led project with internal medicine residents focused on Clinical Decision Support was designed, implemented, and reviewed, with the objectives of educating clinical teams and positively impacting patient care. MATERIALS AND METHODS: During the 2017-2018 academic year, senior radiology residents (PGY-5) led weekly rounds with medicine residents rotating through inpatient floor units. During these rounds, they discussed indications for and types of hospital inpatient imaging studies, exchanged clinical information, directed further imaging workup, and taught the essentials of image interpretation. Participating medical residents' degree of radiology-awareness and opinions were systematically surveyed at the conclusion of the academic year. Thirty-four out of a total of 161 (21%) Internal Medicine residents responded to the survey. Thirty one percent of these residents could identify an instance where radiology-led rounds altered patient management and 94% acknowledged an increase in medical knowledge. Sixty-one percent believed evidence-based choice for imaging orders was enhanced by attending radiology-led rounds and 64% developed a better understanding of resources available to guide image ordering. Forty-nine percent of residents made suggestions to their Internal Medicine attending physician or more senior trainee or otherwise applied something learned during radiology-led rounds and 42% cancelled or ordered a study based on what they learned or discussed in radiology rounds. Thirty-nine percent of medicine residents stated that these rounds changed their perception of the role of the radiologist and 75% expressed the desire to see increased participation by radiologists in their daily workflow. Radiology resident-led educational medicine rounds promote cross-specialty collaboration, further educate trainees, and directly affect patient management. It is therefore valuable for radiology trainees to directly engage in the teaching of other medical providers, to enhance their own consultative skill set, promote face-to-face interactions with other physicians, and to directly impact patient care.

Best Practices: Application of NI-RADS for Posttreatment Surveillance Imaging of Head and Neck Cancer.

Imaging surveillance is an important component of posttreatment management of head and neck cancers. There is variability in the surveillance regimen used by various practitioners and institutions, with no official National Comprehensive Cancer Network guidelines for patients showing no symptoms beyond 6 months posttreatment. Moreover, imaging of the neck after treatment is a complex examination with significant interreader heterogeneity, particularly in terms of the manner in which degree of suspicion for disease recurrence is expressed. The Neck Imaging Reporting and Data System (NI-RADS) was introduced by the American College of Radiology (ACR) in 2018 as a practical guide for the interpreting radiologist. NI-RADS is a proposed interpretive framework that can be applied to any standardized or institutional surveillance imaging protocol. NI-RADS simplifies communication between radiologists and referring clinicians and provides management guidance linked to specific levels of suspicion. The ACR NI-RADS Committee also provided general best practice recommendations for imaging surveillance modality and timing in the 2018 white paper. This article will review existing literature regarding choice of modality and timeline for surveillance in treated cancer of the head and neck. NI-RADS will then be presented as an approach to imaging reporting, interpretation, and design of next steps in management.

The Brain-Nose Interface: A Potential Cerebrospinal Fluid Clearance Site in Humans.

The human brain functions at the center of a network of systems aimed at providing a structural and immunological layer of protection. The cerebrospinal fluid (CSF) maintains a physiological homeostasis that is of paramount importance to proper neurological activity. CSF is largely produced in the choroid plexus where it is continuous with the brain extracellular fluid and circulates through the ventricles. CSF movement through the central nervous system has been extensively explored. Across numerous animal species, the involvement of various drainage pathways in CSF, including arachnoid granulations, cranial nerves, perivascular pathways, and meningeal lymphatics, has been studied. Among these, there is a proposed CSF clearance route spanning the olfactory nerve and exiting the brain at the cribriform plate and entering lymphatics. While this pathway has been demonstrated in multiple animal species, evidence of a similar CSF egress mechanism involving the nasal cavity in humans remains poorly consolidated. This review will synthesize contemporary evidence surrounding CSF clearance at the nose-brain interface, examining across species this anatomical pathway, and its possible significance to human neurodegenerative disease. Our discussion of a bidirectional nasal pathway includes examination of the immune surveillance in the olfactory region protecting the brain. Overall, we expect that an expanded discussion of the brain-nose pathway and interactions with the environment will contribute to an improved understanding of neurodegenerative and infectious diseases, and potentially to novel prevention and treatment considerations.