Search

The arachnoid membranes are projections of connective tissue in the subarachnoid space that connect the arachnoid mater to the pia mater. These are underappreciated and largely unrecognized by most neuroradiologists despite being found to be increasingly important in the pathogenesis, imaging, and treatment of communicating hydrocephalus. This review aims to provide neuroradiologists with an overview of the history, embryology, histology, anatomy, and normal imaging appearance of these membranes, as well as some examples of their clinical importance.

Objective: The volumes of various brain regions can be rapidly quantified using automated magnetic resonance imaging tools. While these appear to be useful at face value, their formal clinical utility is not yet understood, particularly for non-neuroradiologists and in patients presenting with suspected dementia. This study investigated the utility of an automated normative morphometry tool on determinations of brain atrophy by psychiatrists and radiologists in a tertiary hospital. Methods: Consecutive magnetic resonance scans ( n = 110) of patients referred with suspected neurodegenerative disorders were obtained retrospectively and rated by two neuroradiologists, two general radiologists and four psychiatrists over two sessions. First, conventional magnetic resonance sequences were shown. Then, morphometry colour-coded maps, which segmented T1-weighted magnetisation prepared rapid gradient echo images into brain regions and visualised these regions in colour according to their volumetric standard deviation from a normative population, were added to the second reading which occurred ⩾6 weeks later. Presence and laterality of atrophy in frontal, parietal and temporal lobes and hippocampal regions were measured using a digital checklist. The primary outcome of inter-rater agreement on atrophy was measured with Fleiss’ Kappa (κ). We also evaluated the accuracy of the atrophy ratings for differentiating post hoc diagnosis of subjective cognitive impairment, mild cognitive impairment and dementia. Results: Agreement among all raters was fair in frontal lobe and moderate in other regions with conventional method (κ = 0.362–0.555). With morphometry, higher agreement was seen in all regions (κ = 0.551–0.654), reaching significant improvement in the frontal and temporal lobes. No significant improvement was seen within the various disciplines, except in frontal lobes rated by psychiatrists. Accuracy of atrophy ratings on determining post hoc diagnosis was significantly improved for distinguishing subjective cognitive impairment versus dementia. Conclusion: In routine clinical assessment, automated normative morphometry complements the determination of regional atrophy and improves inter-rater agreement regardless of neuroradiology experience.

The radiology report represents the sum of a radiologist's highest level of synthesis and insight into a patient's condition. It is the most important product that radiologists generate to help direct patient care. Despite the self-evident importance of clear and effective radiology reporting, radiologists usually receive little or no formal reporting education during training. Instead, it is learned in a piecemeal and often indirect fashion through occasional correction and imitating the reports of other radiologists. The audience of the radiology report extends far beyond the ordering provider and includes patients and their families, medical support staff, subspecialty providers, other radiologists, and research interests. Creating a report that fulfills the needs of this diverse group is a formidable if not quixotic ambition. However, there are certain key principles to reporting the imaging findings, impression, and recommendations that serve as a guide and promote careful consideration about how reports are understood. The findings section should emphasize short, informative, and factual observations while avoiding inappropriate interpretation, excessive use of terms of perception, and redundancy. The impression is the thoughtful synthesis of the meaning of the findings leading to a diagnosis, a differential diagnosis, and management recommendations. Creating a clear and impactful impression allows radiologists to provide the highest level of clinical care and direction but takes time and effort beyond simply restating the findings. The impression should use language that is understandable, memorable, and actionable. Reporting skills require ongoing attention and must adapt to the evolving practice patterns and communication styles in medicine. ©RSNA, 2020.

Radiology signs have long been described in ways that communicate the imagery around us to enhance our cognitive perception. Here, we describe the use and limitations of 10 such signs in neuroradiology, divided into three groups. The first are signs that are reliable for a specific diagnosis, such as the Medusa head sign indicating a developmental venous anomaly, or a racing car sign in agenesis of corpus callosum. The second group of signs helps us to diagnose rare conditions, such as the onion skin sign in Balo’s concentric sclerosis. The third group is of unreliable signs that may lead clinicians astray. For example, the absence of a swallow-tail sign in Parkinson’s disease or the presence of a hummingbird sign and Mickey Mouse sign in progressive supranuclear palsy. The appropriate use of these signs in clinical practice is essential.

Nitrous oxide abuse is a rare cause of vitamin B12 deficiency and consequent subacute combined degeneration of the spinal cord. Worldwide and Australian statistics indicate that recreational use of nitrous oxide is increasing. We report four cases of females aged 18-24 years presenting with clinical symptoms of subacute combined degeneration of the spinal cord. MRI during admission demonstrated the classic findings of T2 hyperintensity, predominantly within the dorsal columns of the spinal cord, with variable involvement of the lateral corticospinal tracts. These cases highlight the ready availability of nitrous oxide and the fact that heavy prolonged recreational use is occurring in the community. It is important that clinicians in emergency and community settings are alerted to this unusual cause of subacute combined degeneration of the spinal cord because early aggressive vitamin B12 replacement together with behavioural change can reverse this disabling neurological syndrome.

BACKGROUND: We explored perceptions and preferences regarding the conversion of in-person to virtual conferences as necessitated by travel and in-person meeting restrictions. METHODS: A 16-question online survey to assess preferences regarding virtual conferences during the COVID-19 pandemic and future perspectives on this subject was disseminated internationally online between June and August 2020. FINDINGS: A total of 508 responses were received from 73 countries. The largest number of responses came from Italy and the USA. The majority of respondents had already attended a virtual conference (80%) and would like to attend future virtual meetings (97%). The ideal duration of such an event was 2-3 days (42%). The preferred time format was a 2-4-h session (43%). Most respondents also noted that they would like a significant fee reduction and the possibility to attend a conference partly in-person and partly online. Respondents indicated educational sessions as the most valuable sections of virtual meetings. The reported positive factor of the virtual meeting format is the ability to re-watch lectures on demand. On the other hand, the absence of networking and human contact was recognized as a significant loss. In the future, people expressed a preference to attend conferences in person for networking purposes, but only in safer conditions. CONCLUSIONS: Respondents appreciated the opportunity to attend the main radiological congresses online and found it a good opportunity to stay updated without having to travel. However, in general, they would prefer these conferences to be structured differently. The lack of networking opportunities was the main reason for preferring an in-person meeting. KEY POINTS: • Respondents appreciated the opportunity to attend the main radiological meetings online, considering it a good opportunity to stay updated without having to travel. • In the future, it is likely for congresses to offer attendance options both in person and online, making them more accessible to a larger audience. • Respondents indicated that networking represents the most valuable advantage of in-person conferences compared to online ones.

Correct catheter position is crucial to ensuring appropriate function of the catheter and avoid complications. This paper describes a dataset consisting of 50,612 image level and 17,999 manually labelled annotations from 30,083 chest radiographs from the publicly available NIH ChestXRay14 dataset with manually annotated and segmented endotracheal tubes (ETT), nasoenteric tubes (NET) and central venous catheters (CVCs)., Measurement(s)Catheter DeviceTechnology Type(s)AnnotationSample Characteristic - OrganismHomo sapiens Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.15113043

There is a growing understanding of the prognostic importance of non-contrast-enhancing tumor in glioblastoma, and recent attempts at more aggressive management of this component using neurosurgical resection and radiosurgery have been shown to prolong survival. Optimizing these therapeutic strategies requires an understanding of the features that can distinguish non-contrast-enhancing tumor from other processes, in particular vasogenic edema; however, the limited and heterogeneous manner in which it has been defined in the literature limits clinical translation. This review covers pertinent literature on our growing understanding of non-contrast-enhancing tumor and focuses on key conventional MR imaging features for improving its delineation. Such features include subtle differences in the degree of FLAIR hyperintensity, gray matter involvement, and focal mass effect. Improved delineation of tumor from edema will facilitate more aggressive management of this component and potentially realize associated survival benefits.

Purpose To determine the incidence of the ‘dot sign’ in patients with colloid cysts of the third ventricle and to characterise its MRI appearances. Materials and Methods Single institution retrospective analysis between January 2007 and October 2016 of all patients with either an imaging or imaging and histology-confirmed diagnosis of colloid cysts of the 3rd ventricle was undertaken. For all cases, MRI signal intensities of the cyst fluid component were graded by two independent radiologists relative to brain parenchyma. Presence of a dot, and if present, its size and relative position within the cyst were recorded. Signal intensities of the dot were then similarly assessed. Results 37 cases of colloid cyst were identified. Of these 37.8% (n = 14) demonstrated the dot sign. The majority (11 of 14) were observed inferiorly within the cyst; two cases were anteroinferior, and one other was posterior. All identified intracystic nodules displayed low signal intensity with respect to cyst fluid on T2 weighted sequences, and only two nodules were hypointense to fluid on T1-weighted imaging, with the remainder either iso- or hyperintense. Conclusions An intracystic low T2 ‘dot’ is a common MRI feature of colloid cysts of the third ventricle, and to our knowledge not previously systematically described. Presence of such a dot should not only not dissuade from a diagnosis of colloid cyst being made, but should in fact be used to strengthen the imaging diagnosis.

Background: methodological challenges limit the use of brain atrophy and lesion burden measures in the followup of multiple sclerosis (MS) patients on clinical routine datasets. Objective: to determine the feasibility of T2-FLAIR-only measures of lateral ventricular volume (LVV) and salient central lesion volume (SCLV), as markers of disability progression (DP) in MS. Methods: a total of 3,228 MS patients from 9 MSBase centers in 5 countries were enrolled. Of those, 2,875 (218 with clinically isolated syndrome, 2,231 with relapsing-remitting and 426 with progressive disease subtype) fulfilled inclusion and exclusion criteria. Patients were scanned on either 1.5 T or 3 T MRI scanners, and 5,750 brain scans were collected at index and on average after 42.3 months at post-index. Demographic and clinical data were collected from the MSBase registry. LVV and SCLV were measured on clinical routine T2-FLAIR images. Results: longitudinal LVV and SCLV analyses were successful in 96% of the scans. 57% of patients had scanner related changes over the follow-up. After correcting for age, sex, disease duration, disability, disease-modifying therapy and LVV at index, and follow-up time, MS patients with DP (n = 671) had significantly greater absolute LVV change compared to stable (n = 1,501) or disability improved (DI, n = 248) MS patients (2.0 mL vs. 1.4 mL vs. 1.1 mL, respectively, ANCOVA p < 0.001, post-hoc pair-wise DP vs. Stable p = 0.003; and DP vs. DI, p = 0.002). Similar ANCOVA model was also significant for SCLV (p = 0.03). Conclusions: LVV-based atrophy and SCLV-based lesion outcomes are feasible on clinically acquired T2-FLAIR scans in a multicenter fashion and are associated with DP over mid-term., Novartis; Genzyme-Sanofi; Biogen; Merck; Genentech; Abbvie; Bayer AG; Celgene/ BMS; Mallinckrodt Pharmaceuticals, Inc.; WebMD Global; Teva; BioCSL; Almirall; Roche; Generica; Deva; Nerve Research Foundation; Multiple Sclerosis Research Australia; Keystone Heart; Bristol Myers Squibb; EMD Serono; V-WAVE Medical; Mapi Pharma; Protembis

Background Succinic semialdehyde dehydrogenase (SSADH) deficiency is a rare neurometabolic disorder resulting in a heterogeneous clinical phenotype. Adolescent and adult patients with SSADH deficiency may present with OCD symptoms. There is minimal literature regarding the pathological basis of OCD symptoms and their management amongst SSADH deficiency patients. Case presentation A 26-year-old woman with SSADH deficiency experienced obsessional slowness and hesitancy in her activities of daily living, with motor rituals and stereotypies of her hands and face. Neuroimaging revealed T2 hyperintensities of the globi pallidi bilaterally. Commencement of the serotonergic escitalopram moderately improved her OCD symptoms. The addition of the dopaminergic pramipexole hydrochloride yielded further improvement, following unsuccessful trial of other adjuncts: risperidone, methylphenidate and mirtazapine. Conclusions Pallidal pathology may explain the manifestation of OCD symptoms amongst individuals with SSADH deficiency. Serotonergic and concomitant dopaminergic therapy may be a viable treatment regimen for SSADH deficiency patients presenting with OCD symptoms.

Tuberous sclerosis complex (TSC) is a multisystem autosomal dominant hamartoma syndrome caused by mutations in TSC1 or TSC2 genes, leading to upregulation of cell growth signalling pathways. Subependymal giant cell astrocytomas (SEGAs) are seen almost exclusively in TSC patients. We report a 'solitary SEGA' in an adult patient, with confirmed deletion of the entire TSC2 gene on tumour tissue DNA, in the absence of detectable constitutional mutation or clinical manifestations of TSC. These rare cases may be secondary to somatic mosaicism and provide an opportunity to explore the genetic basis of the syndrome and its related tumours.

A circulating biomarker has potential to provide more accurate information for glioma progression post treatment, however no such biomarker is currently available. We aimed to discover a microRNA serum biomarker for longitudinal monitoring of glioma patients.A prospectively collected cohort of 91 glioma patients and 17 healthy controls underwent pre and post-operative serum miRNA profiling using Nanostring®. Differentially expressed miRNAs were discovered using a machine learning random forest analysis. Candidate miRNAs were then assessed by droplet digital PCR in 11 patients with multiple follow up samples and compared to tumor volume based on magnetic resonance imaging.A 9-gene miRNA signature was identified that could distinguish between glioma and healthy controls with 99.8% accuracy. Two miRNAs miR-223 and miR-320e, best demonstrated dynamic changes that correlated closely with tumor volume in LGG and GBM respectively. Importantly, miRNA levels did not increase in two cases of pseudo-progression, indicating the potential utility of this test in guiding treatment decisions.We identified a highly accurate 9-miRNA signature associated with glioma serum. Additionally, we observed dynamic changes in specific miRNAs correlating with tumor volume over long-term follow up. These results support a large prospective validation study of serum miRNA biomarkers in glioma.

Investigation of cerebrovascular incidents typically involve non-contrast intracranial computed tomography (CT) and CT angiography (CTA) of the arch of aorta to vertex with or without CT perfusion. Though rare, inadvertent direct arterial contrast injection is a potentially serious complication which can alter contrast distribution and timing resulting in non-diagnostic intracranial studies. If unnoticed, they can be misinterpreted as pathology leading to further unnecessary investigations, increasing patient radiation dose and delaying appropriate management. To date, there have been two documented case reports describing arterial contrast injection in cerebral CTA or CT perfusion. We describe two further cases of arterial contrast administration. Furthermore, by describing various contrast enhancement patterns in normal and variant anatomy - such as bovine aortic arch, vertebral artery dominance, posterior inferior cerebellar artery (PICA) continuation of vertebral artery and fetal posterior communicating artery (PCOM) - we hope to improve clinician recognition of inadvertent arterial contrast injection in a timely fashion.

Introduction To evaluate the accuracy of deep convolutional neural networks (DCNNs) for detecting neck of femur (NoF) fractures on radiographs, in comparison with perceptual training in medically-naive individuals. Methods This study extends a previous study that conducted perceptual training in medically-naive individuals for the detection of NoF fractures on a variety of dataset sizes. The same anteroposterior hip radiograph dataset was used to train two DCNNs (AlexNet and GoogLeNet) to detect NoF fractures. For direct comparison with perceptual training results, deep learning was completed across a variety of dataset sizes (200, 320 and 640 images) with images split into training (80%) and validation (20%). An additional 160 images were used as the final test set. Multiple pre-processing and augmentation techniques were utilised. Results AlexNet and GoogLeNet DCNNs NoF fracture detection accuracy increased with larger training dataset sizes and mildly with augmentation. Accuracy increased from 81.9% and 88.1% to 89.4% and 94.4% for AlexNet and GoogLeNet respectively. Similarly, the test accuracy for the perceptual training in top-performing medically-naive individuals increased from 87.6% to 90.5% when trained on 640 images compared with 200 images. Conclusions Single detection tasks in radiology are commonly used in DCNN research with their results often used to make broader claims about machine learning being able to perform as well as subspecialty radiologists. This study suggests that as impressive as recognising fractures is for a DCNN, similar learning can be achieved by top-performing medically-naive humans with less than 1 hour of perceptual training.

BACKGROUND AND PURPOSE: The 2016 revision of the World Health Organization Classification of Tumors of the Central Nervous System mandates codeletion of chromosomes 1p and 19q for the diagnosis of oligodendroglioma. We studied whether conventional MR imaging features could predict 1p/19q status. MATERIALS AND METHODS: Patients with previous 1p/19q testing were identified through pathology department records, typically performed on the basis of an oligodendroglial component on routine histology; 69 patients met the inclusion criteria. Preoperative imaging of patients with grade II or III gliomas was retrospectively assessed by 2 neuroradiologists, blinded to the 1p/19q status. Thirteen MR imaging features were first assessed in a small initial cohort ( n = 10), after which the criteria were narrowed for the remaining patients as a validation cohort. RESULTS: There was 85% agreement between radiologists for the overall prediction of 1p/19q status in the validation cohort, with an accuracy of 84%. The presence of >50% T2-FLAIR mismatch and calcification was found to be the most useful for predicting 1p/19q status. The >50% T2-FLAIR mismatch variable was demonstrated in 14 tumors and had 100% specificity for identifying a noncodeleted tumor ( P = .001), with 97% interobserver correlation. Calcification was visualized in 7 tumors, 6 of which were 1p/19q codeleted (specificity, 97%; P = .006), with 100% interobserver correlation. CONCLUSIONS: The presence of >50% T2-FLAIR mismatch is highly predictive of a noncodeleted tumor, while calcifications suggest a 1p/19q codeleted tumor. If formal 1p/19q testing is not possible, a combined MR imaging–histologic assessment may improve the diagnostic accuracy over histology alone.

Köhlmeier-Degos disease is rare idiopathic vasculopathy, the exact pathogenesis of which remains unclear. Here, we review pertinent literatutre and present a case of a Köhlmeier-Degos disease with central nervous system involvement followed-up over 11 years with various neuroimaging modalities. Evolution of neurovascular and neuropathological changes over an extended time period has not been previously described.

In this report, we present a case of an adult patient with a mature teratoma of the conus medullaris. The patient was a 29-year-old postpartum female patient who developed unexplained urinary retention. Lumbar spine magnetic resonance imaging (MRI) examination revealed an intradural partly enhancing mixed cystic and solid lesion with intralesional intrinsic T1 hyperintense components that were suppressed on fat suppressed sequences, inseparable from the conus medullaris. Surgical resection was performed and histopathology findings were consistent with a mature teratoma. The patient made a complete recovery.

Although abducens nerve palsy is an established sequela of head trauma - given the prolonged intracranial course of the nerve - bilateral injury is rare. Here, we present two cases of bilateral traumatic abducens nerve avulsion, in the absence of regional fractures, one of which presented two months following the initial trauma. Additionally, we review the current literature on bilateral abducens nerve palsy secondary to trauma, discussing the anatomy of the nerve's course and potential mechanisms of injury.

Isocitrate dehydrogenase 1 (IDH1) mutations in gliomas have been associated with a frontal lobe location and a greater proportion of noncontrast-enhancing tumour (nCET). The purpose of our study was to validate the utility of MRI imaging features in predicting IDH1 mutations in glioblastomas. Pre-operative MRIs of new glioblastoma patients, consisting of at least FLAIR and T1-weighted post-contrast sequences, were reviewed by a neuroradiologist based primarily on the VASARI feature set. IDH1 mutation testing was performed on all patients using immunohistochemistry. 153 patients met the inclusion criteria, of whom five had IDH1 mutations (3.3%). A frontal lobe location had equivalent frequency in both the IDH1-mutated and IDH1-wildtype cohorts (p=1.000). Three (60%) of the IDH1-mutated tumours had >33% nCET, compared to 21% of IDH1-wildtype (p=0.073). 12 tumours had a frontal lobe epicentre and >33% nCET, all being IDH1-wildtype. All five IDH1-mutated tumours had either a frontal lobe epicentre or >33% nCET, but none had both these features. Our results question the strength of the association between frontal lobe glioblastomas with substantial nCET and IDH1 mutations, as these features are also relatively frequent in IDH1-wildtype tumours, which are much more common. MRI is thus more useful for ruling out an IDH1 mutation rather than strongly suggesting its presence: if a particular glioblastoma does not have a frontal lobe epicentre and has less than 33% nCET, it can be predicted to be IDH1-wildtype with a high degree of confidence.

Intracranial dural arteriovenous fistulas (dAVF) are acquired lesions, with the most commonly reported findings on CT haemorrhage or focal oedema. We describe a case of progressive subcortical calcification on CT secondary to venous hypertension from a high grade dAVF.

BACKGROUND AND PURPOSE: The standard for evaluating interval radiologic activity in MS, side-by-side MR imaging comparison, is restricted by its time-consuming nature and limited sensitivity. VisTarsier, a semiautomated software for comparing volumetric FLAIR sequences, has shown better disease-activity detection than conventional comparison in retrospective studies. Our objective was to determine whether implementing this software in day-to-day practice would show similar efficacy. MATERIALS AND METHODS: VisTarsier created an additional coregistered image series for reporting a color-coded disease-activity change map for every new MS MR imaging brain study that contained volumetric FLAIR sequences. All other MS studies, including those generated during software-maintenance periods, were interpreted with side-by-side comparison only. The number of new lesions reported with software assistance was compared with those observed with traditional assessment in a generalized linear mixed model. Questionnaires were sent to participating radiologists to evaluate the perceived day-to-day impact of the software. RESULTS: Nine hundred six study pairs from 538 patients during 2 years were included. The semiautomated software was used in 841 study pairs, while the remaining 65 used conventional comparison only. Twenty percent of software-aided studies reported having new lesions versus 9% with standard comparison only. The use of this software was associated with an odds ratio of 4.15 for detection of new or enlarging lesions (P = .040), and 86.9% of respondents from the survey found that the software saved at least 2–5 minutes per scan report. CONCLUSIONS: VisTarsier can be implemented in real-world clinical settings with good acceptance and preservation of accuracy demonstrated in a retrospective environment.

Lymphomas affecting the central nervous system (CNS), both primarily and secondarily, are uncommon malignancies. Immunosuppressed states, including iatrogenic immunosuppression following organ transplantation, are the most significant risk factors for developing primary CNS lymphoma (PCNSL). Post-transplant lymphoproliferative disease (PTLD) is a well described complication following bone marrow or solid organ transplantation. PTLD is usually a systemic disease with occasional CNS involvement. The incidence of CNS involvement in PTLD is low, and the majority of these cases tend to be PCNSL. Hodgkin lymphoma PTLD (HL-PTLD) constitutes only a very small percentage of PTLD. We report a rare case of a primary intraventricular CNS classical HL-PTLD in a male patient, 18 years following renal transplantation. The location allowed for safe neurosurgical intervention which resolved the symptom of elevated intracranial pressure and allowed for induction of a Rituximab-based chemotherapy regimen. Both the ventricular location of the PTLD and Hodgkin Lymphoma PTLD are themselves individually quite rare and have not previously been reported together. The unique location allowed safe neurosurgical intervention which quickly resolved the symptom of elevated intracranial pressure and allowed for induction of a Rituximab-based chemotherapy regimen.

Objective: Based on the experiences of neuroimaging psychiatry registrars, we describe several reflections on improving the understanding and integration of magnetic resonance imaging in clinical psychiatry. Conclusion: Better integration of magnetic resonance imaging into clinical psychiatry can be highly productive when our investments are focused on understanding the gaps in clinical knowledge and the systemic barriers involving the patient and relevant clinicians.

Glioblastoma usually presents on imaging as a single peripherally enhancing lesion, but multiple enhancing lesions can occur, termed multifocal if there is a connection between enhancing lesions, or multicentric when no communication is demonstrated. We aim to determine the incidence and prognostic implications of multifocal and multicentric glioblastoma in the era of modern MRI, focusing on the added benefit of T2-weighted fluid-attenuated inversion recovery (FLAIR) imaging. Patients with a new diagnosis of glioblastoma were identified. Preoperative MRI were reviewed to determine whether more than one distinct enhancing lesion was present, and whether there was communication between lesions. The findings were compared against survival data. More than one discrete contrast-enhancing lesion was present in 51 of the 151 patients (34%). Communication between lesions was identified in 47 of these, most commonly direct parenchymal spread (41 patients). The patients with multiple lesions had worse survival (median 176days, compared to 346days), but this difference was not statistically significant (p=0.253). These tumours more frequently involved deep structures (p

Ischaemic strokes are an uncommon occurrence in the setting of glioblastoma, and clinically challenging due to co-existing deficits from the tumour, but important to consider as a possible cause of clinical deterioration. Modern therapies and their associated improvements in survival may lead to a greater overall incidence. The possible underlying causes of ischaemia are multiple, and several factors may contribute in a given patient. This review discusses the causative mechanisms of ischaemic strokes in the setting of glioblastoma, with some illustrative cases.

Spinal angiolipomas are uncommon benign tumours composed of mature fatty tissue and abnormal vascular elements, most commonly found within the posterior spinal epidural space. Most tumours are located within the mid-thoracic spine; in contrast thoracolumbar junction and purely lumbar angiolipomas are rare. We report a case series of four spinal angiolipomas, including a thoracolumbar junction and a purely lumbar tumour.

Purpose Dilated perivascular spaces are a common finding on brain MRI, traditionally classified into three types based on location and relationship to vessels. Recent studies have characterised an additional variant of dilated perivascular spaces that arise within the anterior temporal lobe and have unique neuroimaging features. These particular perivascular spaces are associated with a vascular loop of a branch of the middle cerebral artery (MCA) and commonly demonstrate perilesional T2/FLAIR signal. To our knowledge, these have not previously been described in the frontal lobe. Method Dilated perivascular spaces associated with a vascular loop of a branch of the middle cerebral artery (MCA) identified at our institution were reviewed for imaging characteristics and anatomical location. Results 18 cases were identified. 16 were located in the anterior temporal lobe and two were located in the frontal operculum. All demonstrated internal signal characteristics identical to CSF on all sequences, with no contrast enhancement or susceptibility artefact and variable perilesional T2/FLAIR signal. Conclusions We report further evidence of a distinct subtype of dilated perivascular spaces occurring in the anterior temporal lobe in association with a vascular loop of a branch of the MCA. In addition, we have demonstrated that these may also occur in the frontal operculum. We therefore suggest that these dilated perivascular spaces of the operculum be recognised as a separate, fourth, subtype of perivascular space and propose the term “opercular perivascular cyst”.

Purpose To examine Generative Visual Rationales (GVRs) as a tool for visualizing neural network learning of chest radiograph features in congestive heart failure (CHF). Materials and Methods A total of 103 489 frontal chest radiographs in 46 712 patients acquired from January 1, 2007, to December 31, 2016, were divided into a labeled data set (with B-type natriuretic peptide [BNP] result as a marker of CHF) and unlabeled data set (without BNP result). A generative model was trained on the unlabeled data set, and a neural network was trained on the encoded representations of the labeled data set to estimate BNP. The model was used to visualize how a radiograph with high estimated BNP would look without disease (a "healthy" radiograph). An overfitted model was developed for comparison, and 100 GVRs were blindly assessed by two experts for features of CHF. Area under the receiver operating characteristic curve (AUC), κ coefficient, and mixed-effects logistic regression were used for statistical analyses. Results At a cutoff BNP of 100 ng/L as a marker of CHF, the correctly trained model achieved an AUC of 0.82. Assessment of GVRs revealed that the correctly trained model highlighted conventional radiographic features of CHF as reasons for an elevated BNP prediction more frequently than the overfitted model, including cardiomegaly (153 [76.5%] of 200 vs 64 [32%] of 200, respectively; P < .001) and pleural effusions (47 [23.5%] of 200 vs 16 [8%] of 200, respectively; P = .003). Conclusion Features of congestive heart failure on chest radiographs learned by neural networks can be identified using Generative Visual Rationales, enabling detection of bias and overfitted models. © RSNA, 2018 See also the editorial by Ngo in this issue.

Intracranial involvement is a rare complication of multiple myeloma. It results either from direct extra-osseous spread from adjacent skeletal plasmacytomas or extra-medullary disease via haematogenous dissemination. The imaging appearances are non-specific, and dural, leptomeningeal, and parenchymal involvement can all occur. The purpose of this review is to illustrate the various neuroimaging appearances of this rare entity, focusing on MRI.

Purpose The aim of this study was to compare the volume of individuals who viewed online versions of research articles in 2 peer-reviewed radiology journals and a radiology blog promoted by social media. Methods The authors performed a retrospective study comparing online analytic logs of research articles in the American Journal of Neuroradiology ( AJNR ) and the American Journal of Roentgenology ( AJR ) and a blog posting on Radiopaedia.org from April 2013 to September 2014. All 3 articles addressed the topic of reporting incidental thyroid nodules detected on CT and MRI. The total page views for the research articles and the blog article were compared, and trends in page views were observed. Factors potentially affecting trends were an AJNR podcast and promotion of the blog article on the social media platforms Facebook, Tumblr, and Twitter to followers of Radiopaedia.org in February 2014 and August 2014. Results The total numbers of page views during the study period were 2,421 for the AJNR article and 3,064 for the AJR article. The Radiopaedia.org blog received 32,675 page views, which was 13.6 and 10.7 times greater than AJNR and AJR page views, respectively, and 6.0 times greater than both journal articles combined. Months with activity above average for the blog and the AJNR article coincided with promotion by Radiopaedia.org on social media. Conclusions Dissemination of scientific material on a radiology blog promoted on social media can substantially augment the reach of more traditional publication venues. Although peer-reviewed publication remains the most widely accepted measure of academic productivity, researchers in radiology should not ignore opportunities for increasing the impact of research findings via social media.

Department of Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia Monash Imaging, Monash Health, Clayton, Victoria, Australia Department of Medicine, The University of Melbourne, Parkville, Victoria, Australia Department of Neurosurgery, The Royal Melbourne Hospital, Parkville, Victoria, Australia Department of Surgery, The University of Melbourne, Parkville, Victoria, Australia Department of Radiology, The Royal Melbourne Hospital, Parkville, Victoria, Australia Department of Radiology, The University of Melbourne, Parkville, Victoria, Australia

We present a case of primary central nervous system lymphoma (PCNSL) co-existing with demyelination in a young immunocompetent woman. The patient presented with an expansile, enhancing lesion in the right occipital lobe which was initially attributed to tumefactive demyelination and subsequently proven to be PCNSL. PCNSL is an uncommon malignancy, particularly in young immunocompetent patients, and on MRI classically manifests as a homogeneously enhancing solitary mass with a predilection for periventricular and superficial locations, often contacting ventricular and meningeal surfaces. Tumefactive demyelinating lesions typically present as large white matter lesions with little mass effect or vasogenic oedema and "open-ring" enhancement, with the incomplete portion of the ring on the grey matter side of the lesion. PCNSL and tumefactive demyelinating lesions share some radiological features and thus, as our case report highlights, differentiating between them can be challenging. We discuss how the application of conventional and advanced MRI techniques combined with clinical and laboratory findings can lead to a precise diagnosis, potentially obviating the need for biopsy and facilitating prompt and appropriate treatment.

Diagnosing certain fractures in conventional radiographs can be a difficult task, usually taking years to master. Typically, students are trained ad-hoc, in a primarily-rule based fashion. Our study investigated whether students can more rapidly learn to diagnose proximal neck of femur fractures via perceptual training, without having to learn an explicit set of rules. One hundred and thirty-nine students with no prior medical or radiology training were shown a sequence of plain film X-ray images of the right hip and for each image were asked to indicate whether a fracture was present. Students were told if they were correct and the location of any fracture, if present. No other feedback was given. The more able students achieved the same level of accuracy as board certified radiologists at identifying hip fractures in less than an hour of training. Surprisingly, perceptual learning was reduced when the training set was constructed to over-represent the types of images participants found more difficult to categorise. Conversely, repeating training images did not reduce post-training performance relative to showing an equivalent number of unique images. Perceptual training is an effective way of helping novices learn to identify hip fractures in X-ray images and should supplement the current education programme for students.

Brain deposition of gadolinium following the administration of gadolinium-based contrast agents (GBCAs) was initially reported in 2014. Gadolinium deposition is now recognized as a dose-dependent consequence of exposure. The potential clinical implications are not yet understood. The purpose of this study was to determine radiologists' reporting practices in response to gadolinium deposition.An electronic survey querying radiologists' practices regarding gadolinium deposition was distributed by Radiopaedia.org from November-December 2015.Our study sample included 94 total respondents (50% academic; 27% private practice; 23% hybrid) from 30 different countries (USA 18%). Fifty-seven (62%) radiologists had observed brain gadolinium deposition on MRI brain studies howerver more than half of these (30 of 57) reported detecting dentate T1 shortening only rarely (1/month). Among respondents, 58% (52 of 89) do not or would not include the finding in the radiology report; only 12 (13%) report the finding in the impression of their reports. The most common reason for not reporting gadolinium deposition was the risk of provoking unnecessary patient anxiety (29%, 20 of 70). Recent data on gadolinium deposition has led to a reported practice change in 24 of 87 (28%) of respondents.Recognition of, and attitudes toward, brain gadolinium deposition were inconsistent in this worldwide sample. Most surveyed radiologists do not routinely report dentate T1shortening as a marker of gadolinium deposition. Fear of provoking patient/clinician anxiety and an incomplete understanding of the implications of gadolinium deposition contribute to inconsistencies in reporting.

BACKGROUND AND PURPOSE: Multiple sclerosis monitoring is based on the detection of new lesions on brain MR imaging. Outside of study populations, MS imaging studies are reported by radiologists with varying expertise. The aim of this study was to investigate the accuracy of MS reporting performed by neuroradiologists (someone who had spent at least 1 year in neuroradiology subspecialty training) versus non-neuroradiologists. MATERIALS AND METHODS: Patients with ≥2 MS studies with 3T MR imaging that included a volumetric T2 FLAIR sequence performed between 2009 and 2011 inclusive were recruited into this study. The reports for these studies were analyzed for lesions detected, which were categorized as either progressed or stable. The results from a previous study using a semiautomated assistive software for lesion detection were used as the reference standard. RESULTS: There were 5 neuroradiologists and 5 non-neuroradiologists who reported all studies. In total, 159 comparison pairs (ie, 318 studies) met the selection criteria. Of these, 96 (60.4%) were reported by a neuroradiologist. Neuroradiologists had higher sensitivity (82% versus 42%), higher negative predictive value (89% versus 64%), and lower false-negative rate (18% versus 58%) compared with non-neuroradiologists. Both groups had a 100% positive predictive value. CONCLUSIONS: Neuroradiologists detect more new lesions than non-neuroradiologists in reading MR imaging for follow-up of MS. Assistive software that aids in the identification of new lesions has a beneficial effect for both neuroradiologists and non-neuroradiologists, though the effect is more profound in the non-neuroradiologist group.

Radiology provides a crucial clinical adjunct in patients with plasma cell disorders, in particular multiple myeloma, and its uses are evolving and expanding. This pictorial review illustrates the role of imaging throughout the patient’s clinical course, with specific reference to recently updated international diagnostic criteria. At presentation, imaging optimises characterisation and staging of the plasma-cell disorder, while later in the course of the disease, its roles include the monitoring of disease progression, assessment of post-treatment response and the investigation of clinical deterioration.

Glioblastomas with a substantial proportion of noncontrast-enhancing tumour (nCET) have a variety of imaging appearances. We aimed to determine whether glioblastomas demonstrating a substantial proportion (>33%) of nCET can be sub-classified by different morphologic pattern of nCET. We then assessed whether this improves the ability of MRI to predict isocitrate dehydrogenase-1 (IDH1) mutation status and whether this has prognostic significance independent of IDH1 mutation status. Pre-operative MRIs of patients with a new diagnosis of glioblastoma were reviewed. Tumours with >33% nCET were sub-classified by the dominant morphologic pattern of nCET: mass-like expansion, white matter dissemination, grey matter dissemination or a combination. IDH1 mutation status (by immunohistochemistry) and survival were compared for each pattern. 153 patients met the inclusion criteria, of whom 34 patients demonstrated >33% nCET. 10 patients had a significant mass-like component, either as the dominant pattern (n=4) or as part of a mixed pattern (n=6). The 10 patients with a significant mass-like component had longer survival than those without (median 387days, compared to 241days), though this was not statistically significant (p=0.242). Three patients had R132H-IDH1 mutations and >33% nCET, and all three had a mass-like component. Using the presence of a mass-like component of nCET for predicting IDH1 mutation status improved the positive predictive value, specificity and overall accuracy of MRI. Classification of nCET by morphologic pattern improves the ability of MRI to predict IDH1 mutations and may provide useful prognostic information.

BACKGROUND AND PURPOSE: Histologic grading of intracranial astrocytomas is affected by sampling error and substantial inter- and intraobserver variability. We proposed that incorporating MR imaging into grading will predict patient survival more accurately than histopathology alone. MATERIALS AND METHODS: Patients with a new diagnosis of World Health Organization grades II–IV astrocytoma or mixed oligoastrocytoma diagnosed between September 2007 and December 2010 were identified. Two hundred forty-five patients met the inclusion criteria. Preoperative MRIs were independently reviewed by 2 readers blinded to the histologic grade, and an MR imaging grade was given. The MR imaging and histopathologic grades were compared with patient survival. RESULTS: Patients with grade II or III astrocytomas on histology but evidence of necrosis on MR imaging (consistent with a grade IV tumor) had significantly worse survival than patients with the same histology but no evidence of necrosis on MR imaging ( P = .002 for grade II histology and P = .029 for grade III). Their survival was not significantly different from that in patients with grade IV tumors on histology ( P = .164 and P = .385, respectively); this outcome suggests that all or most are likely to have truly been grade IV tumors. MR imaging evidence of necrosis was less frequent in grade II and III oligoastrocytomas, preventing adequate subgroup analysis. CONCLUSIONS: MR imaging can improve grading of intracranial astrocytomas by identifying patients suspected of being undergraded by histology, with high interobserver agreement. This finding has the potential to optimize patient management, for example, by encouraging more aggressive treatment earlier in the patient9s course.

Extracranial spread from a glioblastoma is rare. We present a case of a 48year-old man with a previously radiologically-stable left temporal lobe glioblastoma presenting with symptoms referrable to the spinal cord. MRI revealed a spinal cord lesion, with the differential including transverse myelitis and tumour. Open surgical biopsy revealed high-grade astrocytoma. Genetic analysis of both the supratentorial and spinal tumours revealed R132H IDH1 mutations, providing evidence that the spinal cord lesion had spread from the supratentorial tumour.

White epidermoids are a rare variant of an intracranial epidermoid cyst that do not exhibit typical 'near- cerebrospinal fluid (CSF)' CT density or MRI intensity. Here, the authors present the case of a 58year old man with an acute onset of aphasia and altered consciousness, due to a large heterogeneous cranial mass in the left frontal region with unusual signal intensity. Subsequent histopathological analysis identified the lesion as an epidermoid cyst.

An acute presentation of a meningioma with spontaneous haemorrhage is rare, with mechanisms of haemorrhage remaining unclear. Here, we present a case of a meningioma causing spontaneous intra-tumoural and subdural haemorrhage in the post-partum setting, to our knowledge not previously described, with review of pertinent literature.

Four-dimensional computed tomography (4D-CT) is a new modality for preoperative localization of parathyroid adenomas. We performed a survey study to describe the role and trends in the utilization of 4D-CT. Of 361 radiologists, 200 (55%) reported that 4D-CT was used in their practices. Nineteen (10%) used 4D-CT as the first-line imaging study; 155 (76%) reported that 4D-CT played a secondary role; and 26 (13%) reported that it is performed routinely in combination with ultrasound and scintigraphy. Early adopters of 4D-CT (use for >3 years) were 3 times more likely to use 4D-CT in a first-line role (18%) when compared with radiologists who used 4D-CT for ≤3 years (6%; P < .05). In conclusion, more than half of radiologists perform 4D-CT, and a majority reported that 4D-CT plays a secondary role. However, this role may change, as utilization is increasing and radiologists may follow early adopters, who are more likely to use it as a first-line study.

Lung cancer is one of the leading causes of cancer-related fatality in the world. Patients display few or even no signs or symptoms in the early stages, resulting in up to 75% of patients diagnosed in the later stages of the disease. Consequently, there has been a call for lung cancer screening amongst at-risk populations. The early detection of malignant pulmonary nodules in CT is one of the suggested methods proposed to diagnose early-stage lung cancer; however, the reported sensitivity of radiologists' ability to accurately detect pulmonary nodules ranges widely from 30 to 97%. 2012 saw Alex Krizhevsky present a paper titled "ImageNet Classification with Deep Convolutional Networks" in which a multilayered convolutional computational model known as a convolutional neural network (CNN) was confirmed competent in identifying and classifying 1.2 million images to a previously unseen level of accuracy. Since then, CNNs have gained attention as a potential tool in aiding radiologists' detection of pulmonary nodules in CT imaging. This review found the use of CNN is a viable strategy to increase the overall sensitivity of pulmonary nodule detection. Small, non-validated data sets, computational constraints, and incomparable studies are currently limited factors of the existing research.

The pineal gland is important in structure, function and in the pathology that can affect it. The significance of the pathology of the gland and its adjacent structures is twofold: anatomical location, and biological behaviour of many of the lesions. The gland is in a critical anatomic location, and as the dorsal portions of the midbrain are compressed, patients may present with obstructive hydrocephalus, and/or with focal neurology. Masses and tumours of the pineal region range widely in behaviour, from the completely benign (eg, pineal cyst) to highly malignant (eg, pineoblastoma). Masses in the pineal region may be benign cysts (most common mass), tumours of various sources as well as rare vascular malformations that result in mass effect. Tumours of the pineal region represent a variety of histologies. Germ cell tumours are the most common: germinomas (50%), teratoma (15%), and choricocarcinoma (5%). Primary tumours of the pineal region make up 15% of all pineal tumours and represent a spectrum of aggressiveness. Other less common tumours also occur in the pineal region including metastatic spread and direct invasion from tumours arising in adjacent structures. Accurate diagnosis is essential to plan appropriate management, and early referral for medical imaging is a necessary first step. Although there is significant overlap in the imaging characteristics of some pineal masses, a distinction between aggressive and benign lesions is usually possible, and invaluable preoperative information is obtained in patients who require histological diagnosis.

Improvements in imaging are increasing the detection of multiple lesions in the setting of glioblastoma. Occasionally distant non-enhancing lesions may be identified which have the appearances of a multicentric low-grade glioma. We aimed to determine the incidence, prognostic significance and diagnostic value of this appearance in new glioblastoma patients. Pre-operative MRIs of patients with a new diagnosis of glioblastoma were reviewed to identify multicentric non-enhancing lesions, defined as areas of FLAIR hyperintensity and mass effect, without post-contrast enhancement, separate from the histologically-proven glioblastoma. Patient survival was compared to glioblastoma patients without these appearances, and follow-up imaging was reviewed. Nine of 151 patients (6 %) had multicentric non-enhancing lesions. Their median survival of 183 days was significantly worse than the 278 days for patients without multicentric nonenhancing lesions (p = 0.025). Follow-up MRIs were performed in four patients. In one patient, there were several additional lesions, one of which developed evidence of necrosis within 22 days of presentation. In the other three patients, the multicentric lesions developed enhancement and evidence of necrosis within 1 year, and became confluent on FLAIR with the dominant lesion. The appearance of a multicentric non-enhancing lesion is an uncommon finding in glioblastoma, but a poor prognostic feature. These lesions progress faster than expected for a low-grade glioma and are thus likely to represent more advanced lesions than their appearances suggest. Confluence with the dominant lesion developing with time suggests that the tumor is more extensive than appreciated on imaging.

Introduction Gemistocytic astrocytoma is the second most common subtype of World Health Organization grade 2 astrocytoma, but has a worse prognosis than other grade 2 lesions. We aim to describe the MR imaging features of histopathologically proven gemistocytic tumours. Methods Ethics approval was obtained from both institutions. Patient consent was not required for this retrospective study. We reviewed MR imaging findings of 16 consecutive cases of histopathologically proven gemistocytic astrocytoma and anaplastic astrocytoma with gemistocytic features. Results Average patient age was 48 years, with a 3:1 male to female ratio. Based on our series, the typical appearance of a gemistocytic astrocytoma is a large, heterogeneous mass most commonly supratentorial and lobar. Regions of cyst formation, partial signal suppression on FLAIR images and contrast enhancement are all common features. Additionally, contrary to previous literature that describes gemistocytic astrocytoma as a purely supratentorial lesion, we present two cases of gemistocytic astrocytoma involving the brainstem. Conclusions The possibility of gemistocytic astrocytoma should be considered in patients presenting with large heterogeneous tumours that have regions of cyst formation, partial FLAIR suppression and contrast enhancement. This may be especially useful in reconciling a lesion with high-grade MR imaging features with low-grade histopathology. An infratentorial location does not preclude the diagnosis of gemistocytic astrocytoma.

BACKGROUND AND PURPOSE: Treating MS with disease-modifying drugs relies on accurate MR imaging follow-up to determine the treatment effect. We aimed to develop and validate a semiautomated software platform to facilitate detection of new lesions and improved lesions. MATERIALS AND METHODS: We developed VisTarsier to assist manual comparison of volumetric FLAIR sequences by using interstudy registration, resectioning, and color-map overlays that highlight new lesions and improved lesions. Using the software, 2 neuroradiologists retrospectively assessed MR imaging MS comparison study pairs acquired between 2009 and 2011 (161 comparison study pairs met the study inclusion criteria). Lesion detection and reading times were recorded. We tested inter- and intraobserver agreement and comparison with original clinical reports. Feedback was obtained from referring neurologists to assess the potential clinical impact. RESULTS: More comparison study pairs with new lesions (reader 1, n = 60; reader 2, n = 62) and improved lesions (reader 1, n = 28; reader 2, n = 39) were recorded by using the software compared with original radiology reports (new lesions, n = 20; improved lesions, n = 5); the difference reached statistical significance (P < .001). Interobserver lesion number agreement was substantial (≥1 new lesion: κ = 0.87; 95% CI, 0.79–0.95; ≥1 improved lesion: κ = 0.72; 95% CI, 0.59–0.85), and overall interobserver lesion number correlation was good (Spearman ρ: new lesion = 0.910, improved lesion = 0.774). Intraobserver agreement was very good (new lesion: κ = 1.0, improved lesion: κ = 0.94; 95% CI, 0.82–1.00). Mean reporting times were