Lobar Microbleeds in the Posterior Cortical Atrophy Syndrome: A Comparison to Typical Alzheimer's Disease.

PURPOSE OF THE STUDY: Posterior cortical atrophy is a clinico-radiographical syndrome that presents with higher-order visual dysfunction and is most commonly due to Alzheimer's disease. Understanding factors associated with atypical presentations of Alzheimer's disease, such as posterior cortical atrophy (PCA), holds promise to shape our understanding of AD pathophysiology. Thus, we aimed to compare MRI evidence of lobar microbleeds (LMBs) in posterior cortical atrophy (PCA) syndrome to typical AD (tAD) and to assess and compare MRI evidence of cerebral amyloid angiopathy (CAA) in each group. FINDINGS: We retrospectively collected clinical and MRI data from participants with PCA (n = 26), identified from an institutional PCA registry, and participants with tAD (n = 46) identified from electronic health records from a single institution. LMBs were identified on susceptibility-weighted imaging (SWI); the Fazekas grade of white matter disease was assessed using FLAIR images, and Boston criteria version 2.0 for cerebral amyloid angiopathy were applied to all data. The proportion of participants with PCA and LMB (7.7%) was lower than for tAD (47.8%) (p = 0.005). The frequency of "probable" CAA was similar in both groups, while "possible" CAA was more frequent in tAD (30.4%) than PCA (0%) (p = 0.001). The Fazekas grades were not different between groups. Lobar microbleeds on SWI were not more common in PCA than in typical AD. Clinicopathological investigations are necessary to confirm these findings. The factors that contribute to the posterior cortical atrophy phenotype are unknown.

Evaluation of Cerebrovascular Reactivity and Vessel Wall Imaging in Patients With Prior COVID-19: A Prospective Case-Control MRI Study.

BACKGROUND. SARS-CoV-2 infection is associated with acute stroke, possibly caused by viral tropism to the vascular endothelium. Whether cerebrovascular endothelial dysfunction and inflammation persist after acute infection is poorly understood. OBJECTIVE. The purposes of this study were to assess the association between prior SARS-CoV-2 infection and cerebrovascular reactivity (CVR) and vessel wall imaging (VWI) abnormalities and to explore the association between CVR impairment and post-COVID neurologic conditions. METHODS. This prospective study included 15 participants with prior SARS-CoV-2 infection (11 women, four men; mean age, 43 years; mean time since infection, 238 days; three with prior critical illness, 12 with prior mild illness; seven with post-COVID neurologic conditions) and 10 control participants who had never had SARS-CoV-2 infection (two women, two men; mean age, 44 years) from July 1, 2021, to February 9, 2022. Participants underwent research MRI that included arterial spin labeling perfusion imaging with acetazolamide stimulus to measure cerebral blood flow (CBF) and calculate CVR. Examinations also included VWI, performed with a contrast-enhanced black-blood 3D T1-weighted sequence. An age- and sex-adjusted linear model was used to assess associations between CVR and prior infection. A t test was used to assess associations between CVR and post-COVID neurologic conditions in participants with previous infection. A difference of proportions test was used to assess associations between VWI abnormalities and infection status. RESULTS. Mean whole-cortex CBF after acetazolamide administration was greater in participants without previous infection than in participants with previous infection (73.8 ± 13.2 [SD] vs 60.5 ± 15.8 mL/100 gm/min; p = .04). Whole-brain CVR was lower in participants with previous infection than those without previous infection (difference, -8.9 mL/100 g/min; p < .001); significantly lower CVR was also observed in participants with previous infection after exclusion of those with prior critical illness. Among participants with previous infection, CVR was lower in those with than those without post-COVID neurologic conditions, although this difference was not significant (16.9 vs 21.0 mL/100 g/min; p = .22). Six of 15 (40%) participants with previous infection versus 1 of 10 (10%) participants without previous infection had at least one VWI abnormality (p = .18). All VWI abnormalities were consistent with atherosclerosis. CONCLUSION. SARS-CoV-2 infection is associated with chronic impairment of CVR. The mechanism is unknown from this study. CLINICAL IMPACT. Future studies are needed to determine the clinical implications of SARS-CoV-2-associated CVR impairment.

Association of Incomplete Neurovascular Imaging After Emergency Department Encounters for Transient Ischemic Attack and Odds of Subsequent Stroke: A National Medicare Analysis.

BACKGROUND. Multisociety guidelines recommend urgent brain and neurovascular imaging for patients with transient ischemic attack (TIA), to identify and treat modifiable stroke risk factors. Prior research suggests that most patients with TIA who present to the emergency department (ED) do not receive prompt neurovascular imaging. OBJECTIVE. The purpose of this study was to evaluate the association between incomplete neurovascular imaging workup during ED encounters for TIA and the odds of subsequent stroke. METHODS. This retrospective study obtained data from the Medicare Standard Analytical Files for calendar years 2016 and 2017; these files contain 100% samples of claims for Medicare beneficiaries. Information was extracted using ICD 10th revision (ICD-10) and CPT codes. Those patients who were discharged from an ED encounter with a TIA diagnosis and who underwent brain CT or brain MRI during or within 2 days of the encounter were identified. Patients were considered to have complete neurovascular imaging if they underwent cross-sectional vascular imaging of both the brain (brain CTA or brain MRA) and neck (neck CTA, neck MRA, or carotid ultrasound) during or within 2 days of the encounter. The association between incomplete neurovascular imaging and a new stroke diagnosis within the subsequent 90 days was tested by multivariable logistic regression analysis. RESULTS. The sample included 111,417 patients (47,370 men, 64,047 women; 26.0% older than 84 years) who had TIA ED encounters. A total of 37.3% of patients (41,592) had an incomplete neurovascular imaging workup. A new stroke diagnosis within 90 days of the TIA ED encounter occurred in 4.4% (3040/69,825) of patients with complete neurovascular imaging versus 7.0% (2898/41,592) of patients with incomplete neurovascular imaging. Incomplete neurovascular imaging was associated with increased likelihood of stroke within 90 days (OR, 1.30 [95% CI, 1.23-1.38]) after adjustment for patient characteristics (age, sex, race and ethnicity, high-risk comorbidities, median county household income) and hospital characteristics (region, rurality, number of beds, major teaching hospital designation). CONCLUSION. TIA ED encounters with incomplete neurovascular imaging were associated with higher odds of subsequent stroke occurring within 90 days. CLINICAL IMPACT. Increased access to urgent neurovascular imaging for patients with TIA may represent a target that could facilitate detection and treatment of modifiable stroke risk factors.

A causative role for remote dural puncture and resultant arachnoid bleb in new daily persistent headache: A case report.

A 24-year-old woman experienced a postdural puncture headache following a labor epidural, recovered following bedrest, and was then without headache for 12 years. She then experienced sudden onset of daily, holocephalic headache persisting for 6 years prior to presentation. Pain reduced with prolonged recumbency. MRI brain, MRI myelography, and later bilateral decubitus digital subtraction myelography showed no cerebrospinal fluid (CSF) leak or CSF venous fistula, and normal opening pressure. Review of an initial noncontrast MRI myelogram revealed a subcentimeter dural outpouching at L3-L4, suspicious for a posttraumatic arachnoid bleb. Targeted epidural fibrin patch at the bleb resulted in profound but temporary symptom relief, and the patient was offered surgical repair. Intraoperatively, an arachnoid bleb was discovered and repaired followed by remission of headache. We report that a distant dural puncture can play a causative role in the long delayed onset of new daily persistent headache.

Unusual neuroimaging findings in spontaneous intracranial hypotension.

PURPOSE: The most common neuroimaging manifestations of patients suffering from spontaneous intracranial hypotension (SIH) include subdural fluid collections, enhancement of the pachymeninges, engorgement of venous structures, pituitary hyperemia, sagging of the brainstem, and cerebellar hemosiderosis. However, infrequently patients may present with separate neuroradiological findings which could be easily mistaken for other pathology. METHODS: We describe patients who presented with unique neuroimaging findings who were eventually found to have a spinal CSF leak or venous fistula. Relevant clinical history and neuroradiology findings are presented, and a relevant review of the literature is provided. RESULTS: We present six patients with a proven CSF leak or fistula who presented with dural venous sinus thrombosis, compressive ischemic injury, spinal hemosiderosis, subarachnoid hemorrhage, pial vascular engorgement, calvarial hyperostosis, and spinal dural calcifications. CONCLUSION: Radiologists should be familiar with atypical neuroimaging manifestations of SIH in order to avoid misdiagnosis and guide the clinical trajectory of the patient towards accurate diagnosis and eventual cure.

Algorithmic Multimodality Approach to Diagnosis and Treatment of Spinal CSF Leak and Venous Fistula in Patients With Spontaneous Intracranial Hypotension.

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.

Jugular Venous Reflux Can Mimic Posterior Fossa Dural Arteriovenous Fistulas on MRI-MRA.

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.

Facial Feminization Surgery: Key CT Findings for Preoperative Planning and Postoperative Evaluation.

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.

COVID-19 associated intracranial vasculopathy-MRI vessel wall imaging as adjunct to emergent CT angiography-a case report.

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.

The regional pattern of abnormal cerebrovascular reactivity in HIV-infected, virally suppressed women.

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. 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. 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. 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. 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.

Facial Feminization Surgery: Key CT Findings for Preoperative Planning and Postoperative Evaluation.

Facial feminization surgery (FFS) 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 presence of a dorsal hump and septal deviation or spurring. In the lower face, 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 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 fraction 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.

Between Always and Never: Evaluating Uncertainty in Radiology Reports Using Natural Language Processing.

The ideal radiology report reduces diagnostic uncertainty, while avoiding ambiguity whenever possible. The purpose of this study was to characterize the use of uncertainty terms in radiology reports at a single institution and compare the use of these terms across imaging modalities, anatomic sections, patient characteristics, and radiologist characteristics. We hypothesized that there would be variability among radiologists and between subspecialities within radiology regarding the use of uncertainty terms and that the length of the impression of a report would be a predictor of use of uncertainty terms. Finally, we hypothesized that use of uncertainty terms would often be interpreted by human readers as "hedging." To test these hypotheses, we applied a natural language processing (NLP) algorithm to assess and count the number of uncertainty terms within radiology reports. An algorithm was created to detect usage of a published set of uncertainty terms. All 642,569 radiology report impressions from 171 reporting radiologists were collected from 2011 through 2015. For validation, two radiologists without knowledge of the software algorithm reviewed report impressions and were asked to determine whether the report was "uncertain" or "hedging." The relationship between the presence of 1 or more uncertainty terms and the human readers' assessment was compared. There were significant differences in the proportion of reports containing uncertainty terms across patient admission status and across anatomic imaging subsections. Reports with uncertainty were significantly longer than those without, although report length was not significantly different between subspecialities or modalities. There were no significant differences in rates of uncertainty when comparing the experience of the attending radiologist. When compared with reader 1 as a gold standard, accuracy was 0.91, sensitivity was 0.92, specificity was 0.9, and precision was 0.88, with an F1-score of 0.9. When compared with reader 2, accuracy was 0.84, sensitivity was 0.88, specificity was 0.82, and precision was 0.68, with an F1-score of 0.77. Substantial variability exists among radiologists and subspecialities regarding the use of uncertainty terms, and this variability cannot be explained by years of radiologist experience or differences in proportions of specific modalities. Furthermore, detection of uncertainty terms demonstrates good test characteristics for predicting human readers' assessment of uncertainty.

Structured Reporting for Findings of Spontaneous Intracranial Hypotension on Brain MRI.

A voluntary structured reporting template (based on the Bern score) for brain MRI examinations performed for suspected spontaneous intracranial hypotension (SIH) was associated with an increase in reporting of intracranial MRI findings of SIH and a reduction in discordant assessments with respect to a reference reader.

Uterine artery pseudoaneurysm in the setting of deep endometriosis: an uncommon cause of hemoperitoneum in pregnancy.

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, due to adjacent appendicitis.

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.

Characteristic MR Imaging Findings of Cerebral Air Embolism Infarcts: A Case Series.

Infarcts from cerebral air embolism (CAE) are rare events with potentially catastrophic clinical consequences. The imaging features of CAE are not well defined in the literature. We report a novel constellation of MR imaging findings of cerebral arterial air emboli induced infarcts in a series of 6 patients. Awareness of the more distinguishing MR-imaging patterns of CAE may help establish this diagnosis and facilitate implementation of timely treatment.ABBREVIATIONS: CAE = cerebral air embolism.