Adult diffuse leptomeningeal glioneuronal tumour with limited leptomeningeal involvement, lack of 1p deletion and BRAF V600E mutation

Diffuse leptomeningeal glioneuronal tumours (DLGNT) are rare primary CNS tumours, traditionally characterised by leptomeningeal growth and usually affecting children. A recent large study defined DLGNT on a molecular basis, of which all demonstrated 1p deletions. The vast majority also demonstrated MAPK/ERK pathway activations, however BRAF V600E mutation has not been previously documented in adult cases. In this case report, we describe an unusual cerebral DLGNT, with limited leptomeningeal spread, intact 1p status and a BRAF V600E mutation.

OCD symptoms in succinic semialdehyde dehydrogenase (SSADH) deficiency: a case report

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.

Unusual enhancement patterns from inadvertent arterial contrast injection during CT angiography

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.

Pernicious azotaemia? A case series of subacute combined degeneration of the cord secondary to nitrous oxide abuse

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.

Post-shunting corpus callosal signal change and review of the literature

MRI signal changes in the corpus callosum can be seen in 8.3% of patients following shunt insertion for obstructive hydrocephalus. Several causes have been hypothesised, including mechanical compression, decompression associated oedema and ischaemia, and overshunting. We present a case of a patient with a pineal tumour of intermediate differentiation (WHO grade III), which had caused long-term obstructive hydrocephalus due to compression of the tectal plate and cerebral aqueduct. Following insertion of a shunt, prominent changes in the corpus callosum became evident on CT and MRI characterised by oedema and swelling, particularly affecting the dorsal surface of the corpus callosum. This pattern of signal change, although dramatic, should not be mistaken for other pathologies.

PACS Integration of Semiautomated Imaging Software Improves Day-to-Day MS Disease Activity Detection

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.

Solitary intraventricular Hodgkin lymphoma post-transplant lymphoproliferative disease (HL-PTLD): Case report

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.

Understanding MRI in clinical psychiatry: perspectives from neuroimaging psychiatry registrars

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.

Non-Contrast-Enhancing Tumor: A New Frontier in Glioblastoma Research

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.

Invisible cortex sign: A highly accurate feature to localize the inferolateral central sulcus

INTRODUCTION

The central sulcus is a key landmark on MRI of the brain, but its inferolateral portion is difficult to identify if unable to trace the sulcus superoinferiorly. The authors observed that the cortex abutting the central sulcus appears isointense to the adjacent white matter on DWI, we named this the 'invisible cortex sign' and our study evaluates whether it could be used to identify the inferolateral central sulcus.

METHODS

Observational study of 108 consecutive 'normal' MRI studies performed from May 2016 to January 2017. A single axial DWI image - obtained in the anterior commissure-posterior commissure plane - was selected from each scan just above the subcentral gyrus such that it included the most inferolateral portion of the central sulcus. These single images were given to 10 readers (neuroradiologists, a neuroradiology fellow and radiology trainees) who marked the central sulcus based on the presence of the 'invisible cortex sign'. Their accuracy in identifying the central sulcus was compared with that of the principal investigators, who used tri-planar T1 volumetric MRI sequences.

RESULTS

One hundred and eight consecutive patients (55 female, 53 male) were selected, ranging from 18 to 81 years old (mean = 40.5, σ = 18.2). The central sulcus was correctly identified in 95.5% of cases (σ = 3.7%; range 89.4-99.1%).

CONCLUSION

The 'invisible cortex sign' is a highly accurate method of identifying the inferolateral central sulcus on a single axial DWI slice without relying on the more superior aspects of the sulcus.

Magnetic resonance characterization of the 'dot sign' in colloid cysts of the third ventricle

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.

Computer vs human: Deep learning versus perceptual training for the detection of neck of femur fractures

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-naïve individuals.

METHODS

This study extends a previous study that conducted perceptual training in medically-naïve 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-naïve 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-naïve humans with less than 1 hour of perceptual training.

The utilisation of convolutional neural networks in detecting pulmonary nodules: a review

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.

MRI Features Can Predict 1p/19q Status in Intracranial Gliomas

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.