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COVID-19 was initially described as a pulmonary disease. Increasing attention is now directed to extrapulmonary disease manifestations mediated by viral tropism to the vascular endothelium. Here, we report a case of an adult patient with COVID-19 who presented to the emergency department with neurological signs disproportionate to pulmonary symptoms and was found to have a subacute ischemic stroke. Imaging studies suggested an active inflammatory vasculopathy. The case highlights the utility of vascular wall imaging studies when positive findings are present on emergent CT angiography. Current treatment algorithms should consider the addition of adjunct intracranial vessel wall imaging to assess for inflammatory vasculopathy when a patient with acute or recent COVID infection presents to the emergency department with stroke.

Cerebral revascularization utilizing a variety of bypass techniques can provide either flow augmentation or flow replacement in the treatment of a range of intracranial pathologies, including moyamoya disease, intracranial atherosclerotic disease, and complex aneurysms that are not amenable to endovascular or simple surgical techniques. Though once routine, the publication of high-quality prospective evidence, along with the development of flow-diverting stents, has limited the indications for extracranial-to-intracranial (EC-IC) bypass. Nevertheless, advances in imaging, assessment of cerebral hemodynamics, and surgical technique have changed the risk-benefit calculus for EC-IC bypass. New variations of revascularization surgery involving multiple anastomoses, flow preserving solutions, IC-IC constructs, and posterior circulation bypasses have been pioneered for otherwise difficult to treat pathology including giant aneurysms, dolichoectasia, and medically refractory intracranial atherosclerosis. This review provides a practical update on recent advances in adult intracranial bypass surgery.

Background and purpose Extracranial-to-intracranial (EC-IC) surgical bypass improves cerebral blood flow (CBF) and cerebrovascular vasoreactivity (CVR) for patients with carotid occlusion. Bypass graft patency and contribution of the graft to the postoperative increase in CVR are challenging to assess. To assess the effectiveness of 4D flow magnetic resonance imaging (MRI) to evaluate bypass graft patency and flow augmentation through the superficial temporal artery (STA) before and after EC-IC bypass. Methods Three consecutive patients undergoing EC-IC bypass for carotid occlusion were evaluated pre- and postoperatively using CVR testing with pre- and poststimulus 4D flow-MRI for assessment of the bypass graft and intracranial vasculature. Results Preoperatively, 2 patients (patients 1 and 3) did not augment flow through either native STA. The third, who had evidence of extensive native EC-IC collateralization on digital subtraction angiography (DSA), did augment flow through the STA preoperatively (CVR = 1). Postoperatively, all patients demonstrated CVR > 1 on the side of bypass. The patient who had CVR > 1 preoperatively demonstrated the greatest increase in resting postoperative graft flow (from 40 to 130 mL/minute), but the smallest CVR, with a poststimulus graft flow of 160 mL/minute (CVR = 1.2). The 2 patients who did not demonstrate augmentation of graft flow preoperatively augmented postoperatively from 10 to 20 mL/minute (CVR = 2.0) and 10-80 mL/minute (CVR = 8.0), respectively. Intracranial flow was simultaneously interrogated. Two patients demonstrated mild reductions in resting flow velocities in all interrogated vessels immediately following bypass. The patient who underwent CVR testing on postoperative day 48 demonstrated a stable or increased flow rate in most intracranial vessels. Conclusion Four-dimensional flow MRI allows for noninvasive, simultaneous interrogation of the intra- and extracranial arterial vasculature during CVR testing, and reveals unique paradigms in cerebrovascular physiology. Observing these flow patterns may aid in improved patient selection and more detailed postoperative evaluation for patients undergoing EC-IC bypass.

OBJECTIVE: The purpose of this study was to assess whole brain and regional patterns of cerebrovascular reactivity (CVR) abnormalities in HIV-infected women using quantitative whole brain arterial spin labeling (ASL). We hypothesized that HIV-infected women would demonstrate decreased regional brain CVR despite viral suppression. DESIGN: This cross sectional study recruited subjects from the Bay Area Women’s Interagency Health Study (WIHS) - a cohort study designed to investigate the progression of HIV disease in women. In addition to conventional noncontrast cerebral MRI sequences, perfusion imaging was performed before and after the administration of intravenous acetazolamide. METHODS: CVR was measured by comparing quantitative ASL brain perfusion before and after administration of intravenous acetazolamide. In order to validate and corroborate ASL-based whole brain and regional perfusion, phase-contrast (PC) imaging was also performed through the major neck vessels. FLAIR and susceptibility weighted sequences were performed to assess for white matter injury and microbleeds, respectively. RESULTS: Ten HIV infected women and seven uninfected, age-matched controls were evaluated. Significant group differences were present in whole brain and regional CVR between HIV infected and uninfected women. These regional differences were significant in the frontal lobe and basal ganglia. CVR measurements were not significantly impacted by the degree of white matter signal abnormality or presence of microbleeds. CONCLUSIONS: Despite complete viral suppression, dysfunction of the neurovascular unit persists in the HIV population. Given the lack of association between CVR and traditional imaging markers of small vessel disease, CVR quantification may provide an early biomarker of pre-morbid vascular disease.

Spontaneous intracranial hypotension (SIH) is a disorder of CSF dynamics that causes a complex clinical syndrome and severe disability. SIH is challenging to diagnose because of the variability of its presenting clinical symptoms, the potential for subtle imaging findings to be easily overlooked, and the need for specialized diagnostic testing. Once SIH is suggested by clinical history and/or supported by initial neuroim-aging, many patients may undergo initial nontargeted epidural blood patching with variable and indefinite benefit. However, data suggest that precise localization of the CSF leak or CSF-venous fistula (CVF) can lead to more effective and durable treatment strategies. Leak localization can be achieved using a variety of advanced diagnostic imaging techniques, although these may not be widely performed at nontertiary medical centers, leaving many patients with the potential for inadequate workup or treatment. This review describes imaging techniques including dynamic fluoroscopic and CT myelography as well as delayed MR myelography and treatment options including percutaneous, endovascular, and surgical approaches for SIH. These are summarized by an algorithmic framework for radiologists to approach the workup and treatment of patients with suspected SIH. The importance of a multidisciplinary approach is emphasized.

Thrombophlebitis is a known complication of head and neck infection, which can result in propagation of infected thrombi and associated complications. While antegrade/downstream propagation of thrombus is well described—the Lemierre syndrome—thrombophlebitis can spread in atypical patterns which has specific diagnostic and treatment considerations. In this series, we highlight 6 cases of atypical thrombophlebitis patterns complicating head and neck infection, 5 of which extend intracranially. Through these pathways, head and neck infections such as oral cavity, oropharynx, or skin can be the culprit of remote, including intracranial, complications, which may be overlooked. Furthermore, understanding pathways of venous drainage and communication can help accurately diagnose thrombophlebitis patterns and associated complications.

Objective Although a substantial proportion of ischemic strokes in persons with HIV infection (PWH) is related to large artery disease, studies evaluating elevated cerebrovascular risk in PWH have focused primarily on microvascular disease. We compared the burden of intracranial large artery disease on vessel wall magnetic resonance imaging (VW-MRI) in PWH and HIV-uninfected individuals. Design Cross-sectional study. Methods We recruited antiretroviral therapy-treated PWH with undetectable plasma viral load and HIV-uninfected individuals. All participants were ≥ 40 years of age and at moderate to high cardiovascular risk. We used Poisson and mixed effects logistic regression models to compare the number and associated characteristics of enhancing intracranial arteries on VW-MRI by HIV status. Results Of 46 participants (mean age 59 years), 33 were PWH. PWH had nearly four-fold as many enhancing intracranial arteries on VW-MRI than HIV-uninfected individuals (rate ratio 3.94, 95% CI 1.57-9.88, p = 0.003). The majority of wall enhancement was eccentric (76%) and short-segment (93%), suggestive of intracranial atherosclerotic disease (ICAD). Sixty-nine percent of enhancing arteries were not associated with luminal narrowing on magnetic resonance angiography. None of these characteristics differed significantly by HIV status. Conclusion In persons at moderate to high cardiovascular risk, HIV infection, even when well-controlled, may be associated with a greater burden of intracranial large artery disease and, specifically, of ICAD. Studies of the mechanisms underlying higher rates of ischemic stroke in PWH should include evaluation for intracranial large artery disease. VW-MRI provides added value as an adjunct to traditional luminal imaging when evaluating cerebrovascular risk in PWH.

BACKGROUND AND PURPOSE The diagnostic utility of contrast MR-imaging in adult new-onset seizures without clinically suspected neoplasia or infection is not well defined in the literature. Imaging guidelines consider both contrast and noncontrast MR-imaging examinations appropriate in this clinical scenario. The purpose of this study was to evaluate the utility of contrast MR-sequences in evaluation of seizure in patients without suspicion for neoplasia or infection. METHODS Imaging and clinical data were reviewed for 103 consecutive patients admitted for phase-1 seizure monitoring with the following criteria: (1) MRI-brain performed with/without intravenous contrast; (2) no clinical suspicion for central nervous system (CNS) infection; and (3) no history of CNS neoplasia, or suspected metastatic disease. Readers designated cases as lesional or nonlesional. Lesional cases were further categorized as either visualized on noncontrast sequences only, contrast sequences only, or both. RESULTS 29/103 (28%) patients had epileptogenic lesions, 74/103 (72%) were nonlesional studies. 29/29 (100%) lesional abnormalities were detected on noncontrast sequences (sensitivity 100% [95 confidence interval (CI): 88-100], specificity 100% [95 CI: 95-100]). 23/29 (79.3%) lesional cases were visualized on both noncontrast and postcontrast sequences. 6/29 (20.7%) were visualized only on noncontrast sequences. No lesional cases were detected exclusively on postcontrast MR sequences. With an observed nonlesional extraneous contrast MR-imaging rate of 72%, estimated excess cost of contrast MR-imaging per 1000 patients using Medicare data was $103,680 USD. CONCLUSIONS Contrast MR-imaging has limited diagnostic utility in initial screening of adult new-onset seizure patients without clinically suspected neoplasia or infection. More judicious use of contrast MR-imaging in this patient population may reduce unnecessary exposure to gadolinium and lower associated healthcare costs.

Stroke is a leading cause of death, disability, and financial burden in the United States. Perhaps more than any other disease process, the rapidity with which the diagnosis and treatment of stroke are successfully achieved is paramount to the reduction of its associated morbidity and mortality. Steno-occlusive intracranial vascular disease, the most notorious culprit of cerebral ischemia and/or hemorrhage, traces its etiology to native and embolic atherosclerosis as well as various forms of vascular inflammation, insult, and dysfunction. Distinguishing between these causes is a critical first step in the diagnosis and treatment of a patient presenting with cerebrovascular compromise. In this chapter, we delineate the clinical and imaging features of cervical and intracranial atherosclerosis, vasculitis, and vasculopathy, along with the evidence behind the treatments which comprise their current-day standard of care. The modern imaging armamentarium is diverse and complex, with contrast-enhanced and non-contrast MR angiography, CT angiography, digital subtraction angiography, and ultrasound; each playing an important role in providing rapid insight into the patient's disease process. Understanding these imaging techniques and their application in the acute setting is critical for the provider caring for stroke patients.

Facial feminization surgery is an increasingly performed component of gender affirmation surgery for transgender women. Preoperative facial CT is performed to plan the adjustment of the patient's masculine characteristics to feminine and to plan operative navigation around specific readily identifiable anatomic structures. In the upper face, surgery is performed to reduce the prominence of the brow and increase the nasofrontal angle; the radiology report should indicate the frontal sinus and supraorbital foramen anatomy. In the midface, rhinoplasty is performed to increase the nasofrontal and nasolabial angles; the radiology report should indicate the presence of a dorsal hump and septal deviation or spurring. In the lower face, the prominence of the chin and squareness of the jaw are adjusted via genioplasty and mandible contouring, respectively; the radiology report should describe the location and potential anatomic variations of the inferior alveolar nerve and mental foramina as well as the presence of dental abnormalities that directly inform the surgical approach. CT may also be performed if there is clinical suspicion for postoperative complications such as hardware fracture or osteotomy through the supraorbital or mental foramen. Familiarity with these findings will facilitate improved communication between radiologists and surgeons, thereby contributing to the care of transgender women.

Dural arteriovenous fistulas (DAVFs) are high-flow acquired shunts that can carry high risk of intracranial hemorrhage. Because DAVFs can often be managed by endovascular means, early and accurate diagnosis can markedly improve patient morbidity. Time-of-flight and arterial spin-labeling MRA have increased the diagnostic utility of MRI for DAVF by showing hemodynamic rather than anatomic evidence of shunting. The purpose of this article is to describe the cases of seven patients who had co-localization of arterial spin-labeling signal intensity and time-of-flight flow-related enhancement in the left skull base, resulting in a misdiagnosis of DAVF and a recommendation for catheter angiography by the interpreting radiologist. Benign jugular venous reflux is identified as a common mechanism in each case, and the physiology behind this imaging pitfall is described. An algorithmic diagnostic approach to differentiating physiologic venous reflux from true posterior skull base DAVFs is presented.

BACKGROUND AND PURPOSE: The aging HIV-infected (HIV+) population has increased vascular comorbidities, including stroke, and increased cognitive deficits compared with the general population. Arterial spin-labeling is a technique to measure cerebral blood flow and is more sensitive than regional volume loss in assessing neurodegenerative diseases and cognitive aging. Previous studies have found global cerebral perfusion abnormalities in the HIV+ participants. In this study, we evaluated the specific regional pattern of CBF abnormalities in older HIV+ participants using quantitative whole-brain arterial spin-labeling. MATERIALS AND METHODS: CBF data from the UCSF HIV Over 60 Cohort and the Alzheimer Disease Neuroimaging Initiative were retrospectively evaluated to identify 19 HIV+ older adults, all with plasma viral suppression (including 5 with HIV-associated neurocognitive disorder); 13 healthy, age-matched controls; and 19 participants with early mild cognitive impairment. CBF values were averaged by ROI and compared among the 3 groups using generalized linear models. RESULTS: When we accounted for age, education, sex, and vascular risk factors, the HIV+ participants demonstrated alterations in regional cerebral perfusion, including hypoperfusion of bilateral temporal, parietal, and occipital brain regions compared with both clinically healthy participants and those with mild cognitive impairment. Arterial spin-labeling showed reasonable test characteristics in distinguishing those with HIV-associated neurocognitive disorder from healthy controls and participants with mild cognitive impairment. CONCLUSIONS: This study found specific CBF patterns associated with HIV status despite viral suppression—data that should animate further investigations into the pathobiologic basis of vascular and cognitive abnormalities in HIV-associated neurocognitive disorders.

Background and purpose HIV infection of the central nervous system (CNS) is a nearly universal feature of untreated systemic HIV infection. While combination antiretroviral therapy (ART) that suppresses systemic infection usually suppresses CNS (CNS) HIV infection, exceptions have been reported with discordance between CSF and blood HIV RNA concentrations such that CSF demonstrates higher HIV concentrations than blood, referred to as CSF HIV escape. Rarely, CSF HIV escape presents with neurological symptoms, called neurosymptomatic escape. Methods In this report, we describe the MRI findings in 6 patients with neurosymptomatic escape who were identified at our institution. Results MR imaging suggests an encephalitis possibly evolving from a distinct HIV subpopulation within the CNS. A major difference between primary HIV infection and the current case series is that untreated HIV encephalitis usually occurs in the setting of late disease and a low CD4 whereas CSF Escape develops in setting of a higher CD4, as well as more robust immune and inflammatory responses. Our findings show a burden and distribution of white matter signal abnormalities atypical for patients adherent to ART and that differs from that seen in untreated HIV encephalitis and leukoencephalopathy. Moreover, these patients may also demonstrate perivascular enhancement, a finding not previously reported in the CSF HIV escape literature. Conclusion Recognition of these imaging characteristics-patchy subcortical white matter intensities and a perivascular pattern of enhancement-may be helpful in recognition and, along with other clinical information and CSF findings, in diagnosis of neurosymptomatic escape.

Rationale and Objectives For both airport baggage screeners and radiologists, low target prevalence is associated with low detection rate, a phenomenon known as “prevalence effect.” In airport baggage screening, the target prevalence is artificially increased with fictional weapons that are digitally superimposed on real baggage. This strategy improves the detection rate of real weapons and also allows airport supervisors to monitor screener performance. A similar strategy using fictional patients could be applied in radiology. The purpose of this study was twofold: (1) to review the psychophysics literature regarding low target prevalence and (2) to survey radiologists' attitudes toward using fictional patients as a quality assurance tool. Materials and Methods We reviewed the psychophysics literature on low target prevalence and airport x-ray baggage screeners. An online survey was e-mailed to all members of the Association of University Radiologists to determine their attitudes toward using fictional patients in radiology. Results Of the 1503 Association of University Radiologists member recipients, there were 153 respondents (10% response rate). When asked whether the use of fictional patients was a good idea, the responses were as follows: disagree (44%), neutral (25%), and agree (31%). The most frequent concern was the time taken away from doing clinical work (89% of the respondents). Conclusions The psychophysics literature supports the use of fictional targets to mitigate the prevalence effect. However, the use of fictional patients is not a popular idea among academic radiologists.

Uterine, ovarian, and placental pathologies are among the differential considerations for a pregnant woman presenting with abdominal and pelvic pain. Imaging plays a key role in the initial work-up of these patients. Sonography is often the first line test; however, evaluation of pelvic pathology can be limited in the gravid state, especially in mid- or late-term pregnancy. We present a case of a pregnant woman who came to the emergency room at 25 weeks with acute abdominal and pelvic pain. Both ultrasound and MR imaging findings revealed intraperitoneal hemorrhage, initially of unknown origin, as well as endometriomas and deep endometriosis. Only postpartum imaging confirmed a uterine artery pseudoaneurysm (PSA) presumably due to decidual reaction in deep endometriosis. We speculate the intraperitoneal hemorrhage was subsequently due to the PSA. This case demonstrates that if hemorrhage is not recognized promptly, it can lead to hemodynamic instability, as well as premature labor and delivery.

Massive ovarian edema is a benign clinical entity, the imaging findings of which can mimic an adnexal mass or ovarian torsion. In the setting of acute abdominal pain, identifying massive ovarian edema is a key in avoiding potential fertility-threatening surgery in young women. In addition, it is important to consider other contributing pathology when ovarian edema is secondary to another process. We present a case of a young woman presenting with subacute abdominal pain, whose initial workup revealed marked enlarged right ovary. Further imaging, diagnostic tests, and eventually diagnostic laparoscopy revealed that the ovarian enlargement was secondary to subacute appendicitis, rather than a primary adnexal process. We review the classic ultrasound and MRI imaging findings and pitfalls that relate to this diagnosis.

For both airport baggage screeners and radiologists, low target prevalence is associated with low detection rate, a phenomenon known as "prevalence effect." In airport baggage screening, the target prevalence is artificially increased with fictional weapons that are digitally superimposed on real baggage. This strategy improves the detection rate of real weapons and also allows airport supervisors to monitor screener performance. A similar strategy using fictional patients could be applied in radiology. The purpose of this study was twofold: (1) to review the psychophysics literature regarding low target prevalence and (2) to survey radiologists' attitudes toward using fictional patients as a quality assurance tool.We reviewed the psychophysics literature on low target prevalence and airport x-ray baggage screeners. An online survey was e-mailed to all members of the Association of University Radiologists to determine their attitudes toward using fictional patients in radiology.Of the 1503 Association of University Radiologists member recipients, there were 153 respondents (10% response rate). When asked whether the use of fictional patients was a good idea, the responses were as follows: disagree (44%), neutral (25%), and agree (31%). The most frequent concern was the time taken away from doing clinical work (89% of the respondents).The psychophysics literature supports the use of fictional targets to mitigate the prevalence effect. However, the use of fictional patients is not a popular idea among academic radiologists.

Background The degree to which people worry about radiation exposure from medical imaging has not been quantified. Such concern is important for clinical decision making and policy generation. Objective The aim of this study was to quantify the degree of worry as a consequence of radiation exposure. Design A time trade-off methodology was used to estimate health state utilities associated with radiation exposure from computed tomography scans in an inclusive sample of physicians. Health state utilities were elicited from in-person interviews using a software-guided, hypothetical scenario in which the subject is exposed to two separate computed tomography scans. Results One hundred and eighteen interviews were conducted. The overall mean and median utility values for the health state of concern due to radiation exposure were 0.95 (95% confidence interval: 0.94–0.96) and 0.98 (interquartile range: 0.91–1.00), respectively. The utility score distribution was highly skewed toward higher values. Five respondents (4.3%) recorded a utility score of ≤0.8 and 17 respondents (14.5%) were willing to sacrifice at least 5 or more years of life to live free of the radiation-exposure worry. Conclusions and relevance The physician respondents generally demonstrated low levels of disutility; however, a subset of physicians expressed much greater disutility for the future risk of malignancy. Given the potential for physicians to influence health care decisions and policies, further study of radiation-related concerns seems warranted. Physicians, patients, and the general public should be aware of the potential impact such differing views held by physicians may have on their clinical recommendations.

In this study, we sought to determine the accuracy of a computer algorithm that automatically assesses head computed tomography (CT) studies in patients with suspected traumatic brain injury (TBI) for features of intracranial hemorrhage and mass effect, employing a neuroradiologist's interpretation as the gold standard. To this end, we designed a suite of computer algorithms that evaluates in a fully automated fashion the presence of intracranial blood and/or mass effect based on the following CT findings: (1) presence or absence of a subdural or epidural hematoma, (2) presence or absence of subarachnoid hemorrhage, (3) presence or absence of an intraparenchymal hematoma, (4) presence or absence of clinically significant midline shift (or=5 mm), and (5) normal, partly effaced, or completely effaced basal cisterns. The algorithm displays abnormal findings as color overlays on the original head CT images, and calculates the volume of each type of blood collection, the midline shift, and the volume of the basal cisterns, based on the above-described features. Thresholds and parameters yielding optimal accuracy of the computer algorithm were determined using a development sample of 33 selected, nonconsecutive patients. The software was then applied to a validation sample of 250 consecutive patients evaluated for suspicion of acute TBI at our institution in 2006-2007. Software detection of the presence of at least one noncontrast CT (NCT) feature of acute TBI demonstrated high sensitivity of 98% and high negative predictive value (NPV) of 99%. There was actually only one false negative case, where a very subtle subdural hematoma, extending exclusively along the falx, was diagnosed by the neuroradiologist, while the case was considered as normal by the computer algorithm. The software was excellent at detecting the presence of mass effect and intracranial hemorrhage, but showed some disagreements with the neuroradiologist in quantifying the degree of mass effect and characterizing the type of intracranial hemorrhage. In summary, we have developed a fully automated computer algorithm that demonstrated excellent sensitivity for acute intracranial hemorrhage and clinically significant midline shift, while maintaining intermediate specificity. Further studies are required to evaluate the potential favorable impact of this software on facilitating workflow and improving diagnostic accuracy when used as a screening aid by physicians with different levels of experience.

Objective The sonographic diagnosis of fetal myelomeningocele has improved mainly because the diagnostic focus has shifted from observation of spinal manifestations to observation of cranial abnormalities. Intracranial diagnostic criteria rely on abnormalities in the posterior fossa. We describe abnormalities in tectal morphologic characteristics that, although well described on magnetic resonance imaging, have received little attention in the sonographic literature. This study analyzed the frequency of this observation and technical aspects that improve its visualization. Methods From a database of obstetric sonograms, we identified all cases of sonographically detected myelomeningocele. The search covered the years 1999 to 2007. We retrospectively reviewed the fetal intracranial findings with special attention to elongation or "beaking" of the tectum. Results A total of 89 fetuses were identified. The mean and median gestational ages were 22 weeks 4 days and 22 weeks 2 days, respectively. Of the 89 cases, 59 (66%) had an abnormal tectal shape. The abnormality was seen in 77% of cases judged to be suboptimally visualized and 62% of cases with good visualization. Tectal abnormalities were seen equally well in fetuses before and after 24 weeks. Finally, tectal abnormalities were seen more frequently as the severity of posterior fossa findings increased. Conclusions Tectal morphologic alteration is a common supratentorial feature of the Chiari II malformation on prenatal sonography both before and after 24 weeks' gestation. Its frequency increases with the severity of posterior fossa abnormalities. Therefore, it may be useful as a supratentorial indicator of both the presence and, potentially, the severity of the Chiari II malformation.

Objective. Visualization of the cavum septi pellucidi (CSP) is considered an integral part of the prenatal second- and third-trimester sonographic evaluations of the fetal neural axis. We have noted that another anatomic structure, the columns of the fornix, can be mistaken for the CSP and result in the missed diagnosis of agenesis of the corpus callosum. Methods. We describe a case in which the columns of the fornix were misinterpreted as representing the CSP during a sonographic evaluation at 18 weeks’ gestation. After a follow-up sonogram at 35 weeks, agenesis of the corpus callosum was detected. A retrospective evaluation of the prevalence of forniceal columns was then performed in 100 consecutive sonograms of pregnancies between 18 and 24 weeks’ gestation. A prospective study was then performed in 20 patients to determine the prevalence of visualization of the columns of the fornix. Results. In 86 of 100 patients, the columns of the fornix were retrospectively identified as discrete and separate structures from the CSP. When additional views were obtained prospectively in the forebrain, the fornix could be identified in all 20 patients. Conclusions. The columns of the fornix may simulate the appearance of the CSP on second- and third-trimester sonograms. The distinction between these structures can be made because the columns of the fornix will show a linear reflection (3 lines) at their interface, whereas the CSP will appear as a fluid-filled triangular or rectangular fluid

Objective The sonographic diagnosis of fetal myelomeningocele has improved dramatically over the past 20 years, mainly because the diagnostic focus has shifted from observation of the spinal abnormality to observation of cranial abnormalities. We describe an abnormality in the shape of the occipital horn that has received scant attention in the sonographic literature. The abnormality is a misshapen occipital horn that is "pointed" rather than rounded. This study analyzed the frequency of this observation and technical aspects that improve its visualization. Methods From a database of obstetric sonograms, we searched for all cases in which open fetal myelomeningocele was sonographically detected. The search covered the period from 1999 to 2007. We then retrospectively reviewed the fetal intracranial findings in each case, with special attention to the contour of the occipital horn of the lateral ventricle. Results A total of 89 fetuses were identified. The mean and median gestational ages were 22 weeks 4 days and 22 weeks 2 days, respectively. Of the 89 cases, 62 (70%) had an occipital horn with a pointed shape. This abnormality was better seen in cases judged to be well visualized and in cases in which digital video clips were available for review. The abnormality was more frequently seen in fetuses at less than 24 weeks' gestation and in fetuses without ventriculomegaly. Finally, it was seen as commonly among fetuses with mild posterior fossa deformations as in those with more severe distortions. Conclusions The occipital point is a common supratentorial feature of the Chiari II malformation. It is seen more commonly in fetuses at less than 24 weeks and in fetuses with normal-sized ventricles. As well, it is seen as commonly among fetuses with mild posterior fossa deformations as in those with more severe distortions. Therefore, its usefulness is enhanced as an observation in the armamentarium of cranial findings for detection of fetal myelomeningocele.