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Background and Purpose: Diagnosing spontaneous intracranial hypotension and associated CSF leaks can be challenging, and additional supportive imaging findings would be useful to direct further evaluation. This retrospective study evaluated whether there was a difference in the prevalence of calvarial hyperostosis in a cohort of patients with spontaneous intracranial hypotension compared with an age- and sex-matched control population., Materials and Methods: Cross-sectional imaging (CT of the head or brain MR imaging examinations) for 166 patients with spontaneous intracranial hypotension and 321 matched controls was assessed by neuroradiologists blinded to the patient's clinical status. The readers qualitatively evaluated the presence of diffuse or layered calvarial hyperostosis and measured calvarial thickness in the axial and coronal planes., Results: A significant difference in the frequency of layered hyperostosis (31.9%, 53/166 subjects versus 5.0%, 16/321 controls, P  < .001, OR = 11.58) as well as the frequency of overall (layered and diffuse) hyperostosis (38.6%, 64/166 subjects versus 13.2%, 42/321 controls, P  < .001, OR = 4.66) was observed between groups. There was no significant difference in the frequency of diffuse hyperostosis between groups (6.6%, 11/166 subjects versus 8.2%, 26/321 controls, P = .465). A significant difference was also found between groups for calvarial thickness measured in the axial ( P  < .001) and coronal ( P  < .001) planes., Conclusions: Layered calvarial hyperostosis is more prevalent in spontaneous intracranial hypotension compared with the general population and can be used as an additional noninvasive brain imaging marker of spontaneous intracranial hypotension and an underlying spinal CSF leak., (© 2022 by American Journal of Neuroradiology.)

Phosphaturic mesenchymal tumors (PMTs) are neoplasms associated with tumor-induced osteomalacia. Patients typically present with pathologic fractures in the setting of chronic hypophosphatemic hyperphosphaturic osteomalacia, as well as gradual muscle weakness, bone pain, and difficulty walking. Because of their rarity and nonspecific symptomatology, phosphaturic mesenchymal tumors often go undiagnosed for years. Even when discovered on imaging, the tumors can be diagnostically challenging for radiologists. Phosphaturic mesenchymal tumors often tend to be small and can be located nearly anywhere in the body, and, therefore, can mimic many other tumors. This case highlights the imaging and pathologic markers of a phosphaturic mesenchymal tumor, often found in a patient with tumor-induced osteomalacia., (© 2022 by American Journal of Neuroradiology.)

Background and Purpose: Photon-counting detector CT is a new technology with a limiting spatial resolution of ≤150 μm. In vivo comparisons between photon-counting detector CT and conventional energy-integrating detector CT are needed to determine the clinical impact of photon counting-detector CT in temporal bone imaging., Materials and Methods: Prospectively recruited patients underwent temporal bone CT examinations on an investigational photon-counting detector CT system after clinically indicated temporal bone energy-integrating detector CT. Photon-counting detector CT images were obtained at an average 31% lower dose compared with those obtained on the energy-integrating detector CT scanner. Reconstructed images were evaluated in axial, coronal, and Pöschl planes using the smallest available section thickness on each system (0.4 mm on energy-integrating detector CT; 0.2 mm on photon-counting detector CT). Two blinded neuroradiologists compared images side-by-side and scored them using a 5-point Likert scale. A post hoc reassignment of readers' scores was performed so that the scores reflected photon-counting detector CT performance relative to energy-integrating detector CT., Results: Thirteen patients were enrolled, resulting in 26 image sets (left and right sides). The average patient age was 63.6 [SD, 13.4] years; 7 were women. Images from the photon-counting detector CT scanner were significantly preferred by the readers in all reconstructed planes ( P  < .001). Photon-counting detector CT was rated superior for the evaluation of all individual anatomic structures, with the oval window (4.79) and incudostapedial joint (4.75) receiving the highest scores on a Likert scale of 1-5., Conclusions: Temporal bone CT images obtained on a photon-counting detector CT scanner were rated as having superior spatial resolution and better critical structure visualization than those obtained on a conventional energy-integrating detector scanner, even with a substantial dose reduction., (© 2022 by American Journal of Neuroradiology.)

Background and Purpose: The CTA "rim sign" has been proposed as an imaging marker of intraplaque hemorrhage in carotid plaques. This study sought to investigate such findings using histopathologic confirmation., Materials and Methods: Included patients had CTA neck imaging <1 year before carotid endarterectomy. On imaging, luminal stenosis and the presence of adventitial (<2-mm peripheral) and "bulky" (≥2-mm) calcifications, total plaque thickness, soft-tissue plaque thickness, calcification thickness, and the presence of ulcerations were assessed. The rim sign was defined as the presence of adventitial calcifications with internal soft-tissue plaque of ≥2 mm in maximum thickness. Carotid endarterectomy specimens were assessed for both the presence and the proportional makeup of lipid material, intraplaque hemorrhage, and calcification., Results: Sixty-seven patients were included. Twenty-three (34.3%) were women; the average age was 70.4 years. Thirty-eight (57.7%) plaques had a rim sign on imaging, with strong interobserver agreement (κ = 0.85). A lipid core was present in 64 (95.5%) plaques (average, 22.2% proportion of plaque composition); intraplaque hemorrhage was present in 52 (77.6%), making up, on average, 13.7% of the plaque composition. The rim sign was not associated with the presence of intraplaque hemorrhage ( P  = .11); however, it was associated with a greater proportion of intraplaque hemorrhage in a plaque ( P  = .049). The sensitivity and specificity of the rim sign for intraplaque hemorrhage were 61.5% and 60.0%, respectively., Conclusions: The rim sign is not associated with the presence of intraplaque hemorrhage on histology. However, it is associated with a higher proportion of hemorrhage within a plaque and therefore may be a biomarker of more severe intraplaque hemorrhage, if present., (© 2022 by American Journal of Neuroradiology.)

Background and Purpose: Percutaneous CT-guided core needle biopsies of head and neck lesions can be safely performed with vigilant planning. This largest-to-date single-center retrospective study evaluates multiple approaches with consideration of special techniques and examines the histopathologic yield., Materials and Methods: Retrospective review of CT-guided core biopsies of head and neck lesions from January 1, 2010, to October 30, 2020, was performed. We recorded the following: patient demographics, sedation details, biopsy needle type and size, lesion location and size, approach, patient positioning, preprocedural intravenous contrast, proceduralists' years of experience, complications, and pathology results., Results: One hundred eighty-four CT-guided core biopsies were evaluated. The initial diagnostic yield was 93% (171/184). However, of 43/184 (23%) originally "negative for malignancy" biopsies, 4 were eventually positive for malignancy via rebiopsy/excision, resulting in a 2% false-negative rate and an adjusted total diagnostic yield of 167/184 (91%). Biopsies were performed by 16 neuroradiologists with variable experience. The diagnostic yield was essentially the same: 91% (64/70) for proceduralists with ≤3 years' experience, and 90% (103/114) with >3 years' experience. The diagnostic yield was 93% (155/166) for lesions of >10 mm. The diagnostic yield per biopsy needle gauge was the following: 20 ga, 81% (13/16); 18 ga, 93% (70/75); 16 ga, 90% (64/71); and 14 ga, 91% (20/22). There were 4 asymptomatic hematomas, with none requiring intervention., Conclusions: Percutaneous CT-guided core needle biopsies are safe procedures for superficial and deep head and neck lesions with a high diagnostic yield. Careful planning and special techniques may increase the number of lesions accessible percutaneously while minimizing the risk of complications., (© 2022 by American Journal of Neuroradiology.)

Vascular venous malformations of the cavernous sinus have multiple imaging features that can be used to distinguish them from other entities in the region. Accurate identification of these lesions is essential: Vascular venous malformation lesions carry considerable risk of intraoperative hemorrhage, so preoperative recognition of vascular venous malformations can greatly impact the treatment strategies used. Nevertheless, because of their scarcity, many radiologists are unfamiliar with the radiologic and clinical features of cavernous sinus vascular venous malformations. This article will describe a case of an asymptomatic vascular venous malformation; outline its imaging, clinical, and pathologic features; and review the relevant literature regarding this diagnosis., (© 2022 by American Journal of Neuroradiology.)

Calcified pseudoneoplasms of the neuraxis are extremely rare non-neoplastic lesions that can exist anywhere in the CNS. Although benign, the lesions can cause substantial neurologic symptoms, typically related to mass effect on adjacent structures. Calcified pseudoneoplasms of the neuraxis can also mimic other entities such as calcified oligodendrogliomas and meningiomas. Nevertheless, the lesions can usually be strongly suggested at the time of imaging due to a number of fairly unique imaging characteristics. Here, the clinical presentation of a patient with a posterior fossa calcified pseudoneoplasm of the neuraxis is described, along with its imaging and pathologic features., (© 2021 by American Journal of Neuroradiology.)

In recent years, there has been substantial progression in the field of stroke clot/thrombus imaging. Thrombus imaging aims to deduce the histologic composition of the clot through evaluation of various imaging characteristics. If the histology of a thrombus can be reliably determined by noninvasive imaging methods, critical information may be extrapolated about its expected response to treatment and about the patient's clinical outcome. Crucially, as we move into an era of stroke therapy individualization, determination of the histologic composition of a clot may be able to guide precise and targeted therapeutic effort. Most radiologists, however, remain largely unfamiliar with the topic of clot imaging. This article will review the current literature regarding clot imaging, including its histologic backdrop, the correlation of images with cellular components and treatment responsiveness, and future expectations., (© 2021 by American Journal of Neuroradiology.)

Background and Purpose: Little is known about associations between spontaneous coronary artery dissection and cervical artery abnormalities. This study sought to assess the prevalence of cervical artery abnormalities among patients with spontaneous coronary artery dissection., Materials and Methods: A retrospective analysis was completed of patients who underwent CTA neck imaging as part of arterial assessment following the diagnosis of spontaneous coronary artery dissection. The internal carotid and vertebral arteries were evaluated for the presence of fibromuscular dysplasia, dissection and/or pseudoaneurysm, ectasia and/or aneurysmal dilation, atherosclerosis, and webs. Carotid tortuosity was categorized into kinks, loops, coils, and retrojugular and/or retropharyngeal carotid courses; vertebral tortuosity was classified by subjective analysis of severity., Results: Two hundred fourteen patients were included in the final cohort, of whom 205 (95.8%) were women; the average age was 54.4 years. Fibromuscular dysplasia was the most frequently observed abnormality (83 patients; 38.8%), followed by dissections and/or pseudoaneurysms ( n = 28; 13.1%), ectasia and/or aneurysmal dilation ( n = 22; 10.3%), and carotid webs ( n = 10; 4.7%). At least 1 type of carotid tortuosity was present in 99 patients (46.3%). The majority ( n = 185; 86.4%) of patients had no carotid atherosclerosis; and 26 (12.2%) had mild; 3 (1.4%), moderate; and 0, severe carotid atherosclerosis., Conclusions: The most common abnormality in the cervical artery vasculature of patients with spontaneous coronary artery dissection is fibromuscular dysplasia. Cervical dissections were higher than previously reported but were not observed in most patients., (© 2021 by American Journal of Neuroradiology.)

Pilomyxoid astrocytoma is a rare form of pediatric CNS malignancy first classified in 2007 by the World Health Organization. The tumors are similar to pilocytic astrocytomas, sharing both some imaging and histologic traits. However, pilomyxoid astrocytomas portend a more ominous prognosis, with more aggressive local tendencies and a greater proclivity for leptomeningeal spread. Although tissue sampling is ultimately required to differentiate pilocytic astrocytomas and pilomyxoid astrocytomas, some imaging features can be used to suggest a pilomyxoid astrocytoma, including homogeneous enhancement, leptomeningeal seeding, and lack of intratumoral cysts. In this article, a case of a hypothalamic pilomyxoid astrocytoma is described, in which the presenting disorder was profound generalized lipodystrophy. The aforementioned imaging characteristics of pilomyxoid astrocytomas are reviewed, as are the pathologic features of such tumors, including their angiocentric cellular arrangement and myxoid background., (© 2021 by American Journal of Neuroradiology.)

Background and Purpose: The relationship between carotid intraplaque hemorrhage and luminal stenosis severity is not well-established. We sought to determine whether intraplaque hemorrhage is related to carotid stenosis and at what degree of stenosis intraplaque hemorrhage most likely contributes to ischemic symptoms., Materials and Methods: Consecutive patients who underwent MR carotid plaque imaging with MPRAGE sequences to identify intraplaque hemorrhage were retrospectively reviewed. Degrees of stenoses were categorized as minimal (<30%), moderate (30%-69%), and severe (>70%). Arteries were categorized into 2 groups: symptomatic (ipsilateral to a cerebral ischemic event) and asymptomatic (from a patient without an ischemic event). Multiple regression analyses were used to determine independent associations between the degree of stenosis and intraplaque hemorrhage and the presence of intraplaque hemorrhage with symptoms among categories of stenosis., Results: We included 449 patients with 449 carotid arteries: Two hundred twenty-five (50.1%) were symptomatic, and 224 (49.9%) were asymptomatic. An increasing degree of stenosis was independently associated with the presence of intraplaque hemorrhage (OR = 1.02; 95% confidence interval, 1.01-1.03). Intraplaque hemorrhage was independently associated with ischemic events in arteries with <30% stenosis (OR = 5.68; 95% CI, 1.49-21.69). No such association was observed in arteries with >30% stenosis. Of symptomatic arteries with minimal stenosis, 8.7% had intraplaque hemorrhage versus 1.7% of asymptomatic arteries ( P = .02). No differences in intraplaque hemorrhage prevalence were found between symptomatic and asymptomatic groups with moderate ( P = .18) and severe stenoses ( P = .99)., Conclusions: The presence of intraplaque hemorrhage on high-resolution plaque imaging is likely most useful in identifying symptomatic plaques in cases of minimal stenosis., (© 2021 by American Journal of Neuroradiology.)

Background and Purpose: Ischemic stroke is the leading cause of long-term disability in adults, but our ability to prognosticate from baseline imaging data is limited. The ASPECTS measures ischemic change in the middle cerebral artery territory on noncontrast CT based on 10 anatomic regions. Here, we investigated whether infarction in particular regions was associated with worse long-term outcome., Materials and Methods: We identified consecutive patients receiving mechanical thrombectomy for ICA/MCA occlusion at 2 comprehensive stroke centers. Pretreatment ASPECTS was assessed by 2 blinded reviewers. Clinical data including demographics, baseline NIHSS score, and 90-day mRS were collected. The relationship between individual ASPECTS regions and the mRS score (0-2 versus 3-6) was assessed using multivariable logistic regression., Results: Three hundred fifty-three patients were included (mean age, 70 years; 46% men), of whom 214 had poor outcome (mRS = 3-6). Caudate (OR = 3.26; 95% CI, 1.33-8.82), M4 region (OR = 2.94; 95% CI, 1.09-9.46), and insula (OR = 1.75; 95% CI, 1.08-2.85) infarcts were associated with significantly greater odds of poor outcome, whereas M1 region infarction reduced the odds of poor outcome (OR = 0.38; 95% CI, 0.14-0.99). This finding remained unchanged when restricted to only patients with good recanalization. No significant associations were found by laterality. Similarly, no region was predictive of neurologic improvement during the first 24 hours or of symptomatic intracerebral hemorrhage., Conclusions: Our results indicate that ASPECTS regions are not equal in their contribution to functional outcome. This finding suggests that patient selection based on total ASPECTS alone might be insufficient, and infarct topography should be considered when deciding eligibility for thrombectomy., (© 2021 by American Journal of Neuroradiology.)

Background and Purpose: Although multishot EPI (readout-segmented EPI) has been touted as a robust DWI sequence for cholesteatoma evaluation, its efficacy in disease detection compared with a non-EPI (eg, HASTE) technique is unknown. This study sought to compare the accuracy of readout-segmented EPI with that of HASTE DWI in cholesteatoma detection., Materials and Methods: A retrospective review was completed of consecutive patients who underwent MR imaging for the evaluation of suspected primary or recurrent/residual cholesteatomas. Included patients had MR imaging examinations that included both HASTE and readout-segmented EPI sequences and confirmed cholesteatomas on a subsequent operation. Two neuroradiologist reviewers assessed all images, with discrepancies resolved by consensus. The ratio of signal intensity between the cerebellum and any observed lesion was noted., Results: Of 23 included patients, 12 (52.2%) were women (average age, 47.8 [SD, 25.2] years). All patients had surgically confirmed cholesteatomas: Six (26.1%) were primary and 17 (73.9%) were recidivistic. HASTE images correctly identified cholesteatomas in 100.0% of patients. On readout-segmented EPI sequences, 16 (69.6%) were positive, 5 (21.7%) were equivocal, and 2 (8.7%) were falsely negative. Excellent interobserver agreement was noted between reviews on both HASTE (κ = 1.0) and readout-segmented EPI (κ = 0.9) sequences. The average signal intensity ratio was significantly higher on HASTE than in readout-segmented EPI, facilitating enhanced detection (mean difference 0.5; 95% CI, 0.3-0.8; P  = .003)., Conclusions: HASTE outperforms readout-segmented EPI in the detection of primary cholesteatoma and disease recidivism., (© 2021 by American Journal of Neuroradiology.)

Optic nerve choristomas are rare entities in which a developmental focus of histologically normal tissue is abnormally located within or along a segment of the optic nerve. Although benign, choristomas may demonstrate slow growth, ultimately resulting in visual field deficits due to compression of the adjacent nerve in the few cases reported in the anterior fossa. Choristomas may have cystic components, though this has not been described in such lesions along the optic nerve. Here, a predominantly cystic optic nerve choristoma is described, with radiologic features mimicking those of an anterior cranial fossa neurenteric cyst. The case highlights the radiology-pathology correlates of choristomas and reviews the surgical approach and management of patients with such lesions., (© 2021 by American Journal of Neuroradiology.)

Persistent stapedial artery is a vascular anomaly with both clinical and surgical implications. Because of its scarcity, however, it remains underrecognized on imaging. Presented here is a series of 10 cases, demonstrating characteristic CT findings associated with this vascular anomaly and its most common pathognomonic imaging signs. The variable morphologic configurations and their corresponding embryologic underpinnings are described. Clinical and surgical implications of this rare anomaly are discussed., (© 2021 by American Journal of Neuroradiology.)

Chordomas are rare primary bone malignancies derived from notochord remnants. The tumors often are slow-growing and often present with indolent, nonspecific symptoms. Nevertheless, chordomas are locally aggressive and highly prone to local recurrence, necessitating precise planning before biopsy and/or surgical resection. Familiarity with the imaging features of chordomas is, therefore, essential. This case highlights the typical imaging and pathologic features of a spinal chordoma as well as the surgical approach and the patient's subsequent outcome., (© 2020 by American Journal of Neuroradiology.)

Background and Purpose: Inadvertent subdural contrast injections can occur during any myelogram. Currently, there are no guidelines defining when residual subdural iodinated contrast will be cleared and no longer interfere with subsequent procedure and imaging. We investigated the time to resolution of subdural contrast using a 2-day lateral decubitus digital subtraction myelogram and associated CT myelogram data in patients undergoing evaluation for spontaneous intracranial hypotension., Materials and Methods: Retrospective review of 63 patients with lateral decubitus digital subtraction myelograms from September 4, 2018, to October 1, 2019, was performed. Patients with 2-day lateral decubitus digital subtraction myelograms on 2 consecutive days, with or without a same-day CT myelogram on day 1 and with a same-day CT myelogram on day 2, were included. Patients with next-day CT covering at least the abdomen and pelvis after either-day injection were also included. In cases of subdural injection, next-day CT scans were evaluated for residual subdural contrast., Results: Of 49 included patients, 5 had subdural injection on day 1, with the second-day CT myelogram available for review. One of these 5 patients had subdural injections on 2 different days and subsequently had chest/abdomen/pelvis CTA a day after the second subdural injection. In all 6 cases of subdural injections, there was complete resolution of subdural contrast on the next-day CT, with the shortest time to resolution of approximately 20.5 hours (range, 20.5-28.5 hours)., Conclusions: Our study suggests that resolution of inadvertently injected subdural contrast occurs within 1 day, and the myelogram can be reattempted as early as the next day., (© 2020 by American Journal of Neuroradiology.)

Spontaneous intracranial hypotension is a condition characterized by low CSF volume secondary to leakage through a dural defect with no identifiable cause. Patients classically present with orthostatic headaches, but this symptom is not specific to spontaneous intracranial hypotension, and initial misdiagnosis is common. The most prominent features of spontaneous intracranial hypotension on intracranial MR imaging include "brain sag" and diffuse pachymeningeal enhancement, but these characteristics can be seen in several other conditions. Understanding the clinical and imaging features of spontaneous intracranial hypotension and its mimickers will lead to more prompt and accurate diagnoses. Here we discuss conditions that mimic the radiologic and clinical presentation of spontaneous intracranial hypotension as well as other disorders that CSF leaks can imitate., (© 2020 by American Journal of Neuroradiology.)

Polymorphous low-grade neuroepithelial tumors of the young (PLNTYs) are recently described CNS tumors. Classically, PLNTYs are epileptogenic and are a subtype of a heterogeneous group of low-grade neuroepithelial tumors that cause refractory epilepsy, such as angiocentric gliomas, oligodendrogliomas, gangliogliomas, and pleomorphic xanthoastrocytomas. Although they are a relatively new entity, a number of imaging and histologic characteristics of PLNTYs are already known. We present the imaging and pathologic findings of such a tumor as well as the surgical approach and clinical management., (© 2020 by American Journal of Neuroradiology.)

The round window serves to decompress acoustic energy that enters the cochlea via stapes movement against the oval window. Any inward motion of the oval window via stapes vibration leads to outward motion of the round window. Occlusion of the round window is a cause of conductive hearing loss because it increases the resistance to sound energy and consequently dampens energy propagation. Because the round window niche is not adequately evaluated by otoscopy and may be incompletely exposed during an operation, otologic surgeons may not always correctly identify associated pathology. Thus, radiologists play an essential role in the identification and classification of diseases affecting the round window. The purpose of this review is to highlight the developmental, acquired, neoplastic, and iatrogenic range of pathologies that can be encountered in round window dysfunction., (© 2020 by American Journal of Neuroradiology.)

Digital subtraction myelography is a valuable diagnostic technique to detect the exact location of CSF leaks in the spine to facilitate appropriate diagnosis and treatment of spontaneous spinal CSF leaks. Digital subtraction myelography is an excellent diagnostic tool for assessment of various types of CSF leaks, and lateral decubitus digital subtraction myelography is increasingly being used to diagnose CSF-venous fistulas. Lateral decubitus digital subtraction myelography differs from typical CT and fluoroscopy-guided myelograms in many ways, including equipment, supplies, and injection and image-acquisition techniques. Operators should be familiar with techniques, common pitfalls, and artifacts to improve diagnostic yield and prevent nondiagnostic examinations., (© 2020 by American Journal of Neuroradiology.)

Background and Purpose: Temporal lobe encephaloceles are increasingly identified and treated as epileptogenic foci. However, there is relatively scant research on the prevalence of asymptomatic encephaloceles. This study set out to describe the frequency of incidental temporal lobe encephaloceles and middle cranial fossa pits., Materials and Methods: A retrospective review was completed of high-resolution (≤0.5-mm section thickness) axial T2WI for internal auditory canal protocol imaging. The presence and laterality of middle cranial fossa pits (small bony defects containing CSF) and encephaloceles (brain parenchyma protrusion through osseous defects with or without bony remodeling) were recorded. Electronic medical records of patients with encephaloceles were searched for a history of seizure., Results: A total of 203 patients were included in the final cohort; 106 (52.2%) women. Forty-five (22.2%) patients had middle cranial fossa pits: 14 (31.1%) unilateral on the right, 17 (37.8%) unilateral on the left, and 14 (31.1%) bilateral. Ten (5.0%) patients had ≥1 encephalocele, none of whom had a documented history of seizure in the electronic medical record. No significant difference was noted in the frequency of pits or encephaloceles based on sex ( P  = .332 and P  = .383, respectively) or age ( P  = .497 and P  = .914, respectively)., Conclusions: Incidental middle cranial fossa pits are common findings, and their prevalence is not related to age or sex. Temporal lobe encephaloceles, though rarer, also exist occasionally among asymptomatic patients. Such findings have diagnostic implications for encephaloceles identified during imaging work-up for epilepsy., (© 2019 by American Journal of Neuroradiology.)

Desmoplastic infantile tumors are rare supratentorial brain tumors that occur in pediatric patients. Desmoplastic infantile tumors are made up of 2 subtypes: desmoplastic infantile gangliogliomas and desmoplastic infantile astrocytomas. Desmoplastic infantile tumors are often identifiable on imaging on the basis of multiple characteristics. Nevertheless, pathologic analysis is required to confirm the diagnosis, particularly when the imaging features are atypical. Here, the radiology findings, surgical approach and subsequent management, and pathology of a desmoplastic infantile ganglioglioma are described., (© 2019 by American Journal of Neuroradiology.)

Background and Purpose: The prevalence of patent facial nerve canals and meningoceles along the facial nerve course is unknown. This study aimed to assess the frequency of such findings in asymptomatic patients., Materials and Methods: A retrospective review was completed of patients with high-resolution MR imaging of the temporal bone whose clinical presentations were unrelated to facial nerve pathology. Facial nerve canals were assessed for the presence of fluid along each segment and meningoceles within either the labyrinthine segment (fluid-filled distention, ≥1.0-mm diameter) or geniculate ganglion fossa (fluid-filled distention, ≥2.0-mm diameter). If a meningocele was noted, images were assessed for signs of CSF leak., Results: Of 204 patients, 36 (17.6%) had fluid in the labyrinthine segment of the facial nerve canal and 40 (19.6%) had fluid in the geniculate ganglion fossa. Five (2.5%) had meningoceles of the geniculate ganglion fossa; no meningoceles of the labyrinthine segment of the canal were observed. No significant difference was observed in the ages of patients with fluid in the labyrinthine segment of the canal or geniculate ganglion compared with those without fluid ( P = .177 and P = .896, respectively). Of the patients with a meningocele, one had a partially empty sella and none had imaging evidence of CSF leak or intracranial hypotension., Conclusions: Fluid within the labyrinthine and geniculate segments of the facial nerve canal is relatively common. Geniculate ganglion meningoceles are also observed, though less frequently. Such findings should be considered of little clinical importance without radiologic evidence of CSF otorrhea, meningitis, or facial nerve palsy., (© 2019 by American Journal of Neuroradiology.)

Background and Purpose: Prior studies regarding acute toxic leukoencephalopathy (ATL) are either small, or preliminary. Our aim was to evaluate etiologies of and differences in imaging severity and outcomes among various etiologies of ATL., Materials and Methods: MRIs of patients with suspected ATL over 15 years were retrospectively reviewed; inclusion criteria were: MRI <3 weeks of presentation with both DWI and FLAIR. These were jointly graded by two neuroradiologists via a previously described score of severity. Clinical outcome was evaluated via both modified Rankin (mRS) and ATL outcome (ATLOS) scores, each being correlated with the DWI and FLAIR scores. Etiologic subgroups of n > 6 patients were statistically compared., Results: Of 101 included patients, the 4 subgroups of n > 6 were the following: chemotherapy ( n = 35), opiates ( n = 19), acute hepatic encephalopathy ( n = 14), and immunosuppressants ( n = 11). Other causes ( n = 22 total) notably included carbon monoxide ( n = 3) metronidazole ( n = 2), and uremia ( n = 1). The mean DWI/FLAIR severity scores were 2.6/2.3, 3.3/3.3, 2.1/2.1 and 2.0/2.5 for chemotherapeutics, opiates, AHE and immunosuppressants, respectively, with significant differences in both imaging severity and outcome ( P = .003-.032) among subgroups, particularly immunosuppressant versus chemotherapy-related ATL and immunosuppressants versus opiates ( P = .004-.032) related ATL. DWI and FLAIR severity weakly correlated with outcome (ρ = 0.289-.349, P < .005) but correlated stronger in the chemotherapy (ρ = 0.460-.586, P < .010) and opiate (ρ =.472-.608, P < .05) subgroups, which had the worst outcomes. ATL clinically resolved in 36%, with severe outcomes in 23% (coma or death, 9/16 deaths from fludarabine). Notable laboratory results were elevated CSF myelin basic protein levels in 8/9 patients and serum blood urea nitrogen levels in 24/91., Conclusions: Clinical outcomes of ATL vary on the basis of etiology, being worse in chemotherapeutic- and opiate-related ATL. Uremia may be a predisposing or exacerbating factor., (© 2019 by American Journal of Neuroradiology.)

Aim: To determine the accuracy of the susceptible vessel sign (SVS) in the detection of arterial occlusion and its clinical implication in acute ischaemic stroke., Materials and Methods: Consecutive ischaemic stroke patients who underwent magnetic resonance imaging (MRI) with susceptibility-weighted imaging (SWI) within 24 hours of symptom onset or time last-seen-well were included. Two independent neuroradiologists reviewed the SWI for evidence of the SVS. Admission stroke severity was determined by the National Institute of Health Stroke Scale (NIHSS) scores, and poor clinical outcome was defined by a 3-months modified Rankin scale (mRS) score >2., Results: The SVS was identified in 26 (12%) of 213 patients with substantial inter-reviewer agreement. The SVS had 99% specificity, 88% negative predictive value (NPV), 51% sensitivity, and 92% positive predictive value (PPV) for detection of acute arterial occlusions. In consecutive stroke patients, the presence of SVS was associated with higher admission NIHSS scores (median 9 versus 3, p<0.001), arterial occlusion (92% versus 12%, p<0.001), larger infarct volume (162±180 ml versus 25±48 ml, p=0.001), and higher rate of poor clinical outcome at 3-months follow-up (58% versus 25%, p=0.001). In the subset of patients with acute arterial occlusion (n=47), the SVS was associated with higher admission NIHSS scores (median of 10 versus 3, p=0.038) and larger infarct volumes (173±184 ml versus 76±112 ml, p=0.034)., Conclusions: The SVS is a highly specific sign of occlusive arterial thrombus, and is associated with larger infarct volume and more severe presentation in a series of consecutive stroke patients, as well as in the subgroup of patients with acute arterial occlusion., (Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Background and Purpose: Acute stroke presentation and outcome depend on both ischemic infarct volume and location. We aimed to determine the association between acute ischemic infarct topology and lesion volume and stroke severity at presentation and discharge., Materials and Methods: Patients with acute ischemic stroke who underwent MR imaging within 24 hours of symptom onset or last seen well were included. Infarcts were segmented and coregistered on the Montreal Neurological Institute-152 brain map. Voxel-based analyses were performed to determine the distribution of infarct lesions associated with larger volumes, higher NIHSS scores at admission and discharge, and greater NIHSS/volume ratios., Results: A total of 238 patients were included. Ischemic infarcts involving the bilateral lentiform nuclei, insular ribbons, middle corona radiata, and right precentral gyrus were associated with larger infarct volumes (average, 76.7 ± 125.6 mL versus 16.4 ± 24.0 mL, P < .001) and higher admission NIHSS scores. Meanwhile, brain stem and thalami infarctions were associated with higher admission NIHSS/volume ratios. The discharge NIHSS scores were available in 218 patients, in whom voxel-based analysis demonstrated that ischemic infarcts of the bilateral posterior insular ribbons, middle corona radiata, and right precentral gyrus were associated with more severe symptoms at discharge, whereas ischemic lesions of the brain stem, bilateral thalami, and, to a lesser extent, the middle corona radiata were associated with higher ratios of discharge NIHSS score/infarct volume., Conclusions: Acute ischemic infarcts of the insulae, lentiform nuclei, and middle corona radiata tend to have larger volumes, more severe presentations, and worse outcomes, whereas brain stem and thalamic infarcts have greater symptom severity relative to smaller lesion volumes., (© 2017 by American Journal of Neuroradiology.)

Background and Purpose: Recent studies demonstrated superiority of CTP to NCCT/CTA at detecting lacunar infarcts. This study aimed to assess CTP's capability to identify lacunae in different intracranial regions., Materials and Methods: Over 5.5 years, 1085 CTP examinations were retrospectively reviewed in patients with acute stroke symptoms with CTP within 12 hours and MRI within 7 days of symptom onset. Patients had infarcts ≤2 cm or no acute infarct on DWI; patients with concomitant infarcts >2 cm on DWI were excluded. CTP postprocessing was automated by a delay-corrected algorithm. Three blinded reviewers were given patient NIHSS scores and symptoms; infarcts were recorded based on NCCT/CTA, CTP (CBF, CBV, MTT, and TTP), and DWI., Results: One hundred thirteen patients met inclusion criteria (53.1% female). On DWI, lacunar infarcts were present in 37 of 113 (32.7%), and absent in 76 of 113 (67.3%). On CTP, lacunar infarcts typically appeared as abnormalities larger than infarct size on DWI. Interobserver κ for CTP ranged from 0.38 (CBF) (P < .0001) to 0.66 (TTP) (P < .0001); interobserver κ for DWI was 0.88 (P < 0.0001). In all intracranial regions, sensitivity of CTP ranged from 18.9% (CBV) to 48.7% (TTP); specificity ranged from 97.4% (CBF and TTP) to 98.7% (CBV and MTT). CTP's sensitivity was highest in the subcortical white matter with or without cortical involvement (21.7%-65.2%) followed by periventricular white matter (12.5%-37.5%); sensitivity in the thalami or basal ganglia was 0%., Conclusions: CTP has low sensitivity and high specificity in identifying lacunar infarcts. Sensitivity is highest in the subcortical white matter with or without cortical involvement, but limited in the basal ganglia and thalami., (© 2016 by American Journal of Neuroradiology.)

Background and Purpose: MR perfusion has shown abnormalities of affected WM in cerebral X-linked adrenoleukodystrophy, but serial data is needed to explore the import of such findings after hematopoietic stem cell transplantation. Our aim was to prospectively measure MR perfusion parameters in patients with cerebral adrenoleukodystrophy pre- and post-hematopoietic stem cell transplantation, and to correlate those measurements with clinical outcome., Materials and Methods: Ten patients with cerebral adrenoleukodystrophy prospectively underwent DSC-MR perfusion imaging at <45 days pre- (baseline), 30-60 days post-, and 1 year post-hematopoietic stem cell transplantation. MR perfusion measurements in the 10 patients and 8 controls were obtained from the parieto-occipital WM, splenium of the corpus callosum, leading enhancing edge, and normal-appearing frontal white matter. MR imaging severity scores and clinical neurologic function and neurocognitive scores were also obtained. MR perfusion values were analyzed in the patients with cerebral adrenoleukodystrophy at each time point and compared with those in controls. Correlations were calculated between the pre-hematopoietic stem cell transplantation MR perfusion values and 1-year clinical scores, with P value adjustment for multiple comparisons., Results: At baseline in patients with cerebral adrenoleukodystrophy, both relative CBV and relative CBF within the splenium of the corpus callosum and parieto-occipital WM significantly differed from those in controls (P = .005-.031) and remained so 1 year post-hematopoietic stem cell transplantation (P = .003-.005). Meanwhile, no MR perfusion parameter within the leading enhancing edge differed significantly from that in controls at baseline or at 1 year (P = .074-.999) or significantly changed by 1 year post-hematopoietic stem cell transplantation (P = .142-.887). Baseline Loes scores correlated with 1-year clinical neurologic function (r = 0.813, P < .0001), while splenium of the corpus callosum relative CBV also significantly correlated with 1-year neurologic function scale and the neurocognitive full-scale intelligence quotient and performance intelligence quotient scores (r = -0.730-0.815, P = .007-.038)., Conclusions: Leading enhancing edge measurements likely remain normal post-hematopoietic stem cell transplantation in cerebral adrenoleukodystrophy, suggesting local disease stabilization. Meanwhile, parieto-occipital WM and splenium of the corpus callosum relative CBV and relative CBF values worsened; this change signified irreversible injury. Baseline splenium of the corpus callosum relative CBV may predict clinical outcomes following hematopoietic stem cell transplantation., (© 2016 by American Journal of Neuroradiology.)

The results of thirty-five joint (hip or knee) replacements in nineteen patients who had an organ transplantation were retrospectively reviewed. The patients received a standard immunosuppressive induction regimen at the time of the transplantation and were maintained on a combination of prednisone, azathioprine, and cyclosporine A. All patients received antibiotics perioperatively, but antibiotic-impregnated bone cement was not used for any procedure. Six joint replacements, in three patients who were an average of 48.2 years old at the time of the arthroplasty, were performed before a renal transplantation. Twenty-four joint replacements, in fourteen patients who were an average of 40.9 years old at the time of the arthroplasty, were performed after an organ transplantation. Two patients, who were an average of 53.8 years old at the time of the arthroplasty, each had a joint replacement both before and after a liver transplantation (a total of five joint replacements). The average duration of follow-up from the first joint replacement was 8.8 years (range, one to twenty-three years). The Harris hip score or The Hospital for Special Surgery knee score was determined at the time of the latest follow-up examination. An infection developed around the implant in five patients who had had the joint replacement after a transplantation. The average interval from implantation of the prosthesis until detection of the infection was 3.4 years (range, one to six years). One patient who had a liver transplant was infected with Pseudomonas aeruginosa and another one was infected with Escherichia coli. One patient who had a renal transplant was infected with Staphylococcus epidermidis; one, with Enterococcus; and one, with Serratia marcescens. We found that patients who had a joint replacement after an organ transplantation had a very high risk of devastating infection. The rate of such infection was 19 per cent (five of twenty-seven joint replacements in sixteen patients).

Evaluation of a painful total knee replacement has been limited to physical examination, aspiration, plain radiographs, and radionuclide studies. Visualization of the polyethylene tibial-bearing component without surgery has not been possible. Polyethylene wear is a well-recognized cause of total knee replacement failure. We have developed an ultrasound method to evaluate polyethylene insert shape and thickness with the ability to clearly demonstrate structural loss of plastic. Before clinical trials, a total knee replacement was cemented into a fresh cadaver knee. Ultrasound imaging of the polyethylene insert was performed in the longitudinal plane using a 10 MHz linear transducer. A characteristic bone/metal/polyethylene interface enabled recognition of the insert material from which its dimension was estimated. The entire perimeter of the liner, the metal tray, and the bone-metal interface was visualized. Five consecutive measurements at each location were performed on each of the 8-, 10-, and 12-mm polyethylene liners with the ultrasonographer blind to the insert thickness. Once removed, measurements were made directly on the liners adjacent to the marked points with an electronic caliper. Coefficient of variation (r2) ranged from 1.6% to 8.3% for the ultrasound measurements, and 0.26% to 1.5% for the caliper measurements. A plot of ultrasound versus caliper measurements allowed calculation of a linear equation, with r2 = 0.98, demonstrating high correlation between the two measurements. Our ultrasound measurements are accurate to 0.5 mm with a 95% confidence interval. Ultrasound is an accurate way to measure the dimensions of the polyethylene liner in total knee replacement arthroplasty. Early experiences with ultrasound evaluation prior to revision have been very encouraging for the evaluation of polyethylene wear, defects, and of prosthetic loosening.

The operative technique of autogenous bone banking of a femoral head from a symptomatic degenerative hip undergoing a primary total hip arthroplasty into an osseous deficiency of an asymptomatic, contralateral, loose acetabular component is described. The rationale for bone banking an autogenous femoral head versus the use of an allograft or iliac crest autograft at a later date is discussed.

The use of duplex ultrasonography for routine noninvasive screening, monitoring, and management of deep venous thrombosis after total hip arthroplasty was evaluated. The reliability of duplex ultrasonography for detection of deep vein thrombosis was confirmed in an initial cohort of 51 total hip arthroplasty patients (102 lower extremities), demonstrating 91% sensitivity, 98% specificity, and 97% accuracy when compared with venography. A second cohort of 110 total hip arthroplasty patients using pneumatic compression stockings and aspirin as deep vein thrombosis prophylaxis underwent screening duplex ultrasonography of both lower extremities on postoperative Day 4. Duplex ultrasonography screening showed 10 (9.1%) patients with proximal deep vein thrombosis and 10 (9.1%) with distal deep vein thrombosis, all of whom were asymptomatic. The 10 patients with proximal deep vein thrombosis on duplex ultrasonography were prescribed therapeutic anticoagulation. Duplex ultrasonography subsequently confirmed resolution of proximal deep vein thrombosis in these patients before discontinuation of anticoagulation; none developed symptomatic pulmonary embolism through 12-month clinical followup. The 10 patients with distal deep vein thrombosis diagnosed by duplex ultrasonography were not treated with anticoagulation, but were monitored by serial duplex ultrasonography through postoperative Day 14 for propagation of distal to proximal deep vein thrombosis; none manifested symptomatic deep vein thrombosis or pulmonary embolism through 12-month clinical followup. The 90 patients with negative duplex ultrasonography results were followed clinically; 3 developed late symptomatic proximal deep vein thrombosis (1 of these later manifested pulmonary embolism). Therefore, duplex ultrasonography was used after total hip arthroplasty for the following: (1) to screen routinely in the hospital for asymptomatic proximal and distal deep vein thrombosis; (2) to monitor for potential propagation of distal to proximal deep vein thrombosis; (3) to minimize exposure to therapeutic anticoagulation by confirming the absence of proximal deep vein thrombosis in 97 of 110 patients; and (4) to demonstrate the effectiveness of mechanical and systemic deep vein thrombosis management by confirming the absence or resolution of deep vein thrombosis in all 110 patients.