Multifocal and multicentric glioblastoma: Improved characterisation with FLAIR imaging and prognostic implications

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<0.001) and the posterior fossa (p=0.045), both of which were associated with worse survival. The presence of multiple enhancing foci in glioblastoma is common, occurring in about one-third of patients, and the majority have multifocal disease. The FLAIR sequence is the crucial sequence for demonstrating a communication between lesions. The worse survival of these patients is, at least in large part related to more extensive tumour dissemination and more frequent involvement of key structures, rather than multiplicity per se.

Parathyroid 4D-CT: Multi-institutional International Survey of Use and Trends

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.

Distinguishing Neuroimaging Features in Patients Presenting with Visual Hallucinations

Visual hallucinations are relatively uncommon presentations in medical and psychiatric clinics, where they are generally regarded as a marker of possible underlying "organic" brain disease. Thus, patients with visual hallucinations are often referred for imaging of the brain. This article presents a pragmatic approach for the radiologist reviewing such imaging. Because conditions that can present with visual hallucinations are legion, a familiarity with the features of the hallucinations themselves, which can serve as clues to the underlying cause, can be helpful in interpreting such cases. We consider the nature of visual hallucinations and the mechanisms underlying their formation. We then provide a framework to guide the search for their cause, first in terms of focal lesions along the visual pathway and then global conditions affecting >1 region.

Ischaemic stroke in the setting of glioblastoma: A case series and review of the literature

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.

Intraparenchymal infratentorial ependymoma

Ependymomas are glial series tumours that can occur throughout the neural axis, usually in close proximity to the ventricles or central canal. While the fourth ventricle is a common location for ependymoma, we present a rare case of an entirely intraparenchymal infratentorial tumour, remote from the ventricular surface, and discuss the imaging characteristics that may suggest the diagnosis. The histological features, which remain identical despite the varied morphology of intraventricular versus intraparenchymal tumours, are also considered.

Four cases of spinal epidural angiolipoma

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.

Demyelination preceding a diagnosis of central nervous system lymphoma

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.

Fragile X-associated tremor/ataxia syndrome: An under-recognised cause of tremor and ataxia

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a progressive degenerative movement disorder resulting from a fragile X "premutation", defined as 55-200 CGG repeats in the 5'-untranslated region of the FMR1 gene. The FMR1 premutation occurs in 1/800 males and 1/250 females, with FXTAS affecting 40-45% of male and 8-16% of female premutation carriers over the age of 50. FXTAS typically presents with kinetic tremor and cerebellar ataxia. FXTAS has a classical imaging profile which, in concert with clinical manifestations and genetic testing, participates vitally in its diagnosis. The revised FXTAS diagnostic criteria include two major radiological features. The "MCP sign", referring to T2 hyperintensity in the middle cerebellar peduncle, has long been considered the radiological hallmark of FXTAS. Recently included as a major radiological criterion in the diagnosis of FXTAS is T2 hyperintensity in the splenium of the corpus callosum. Other imaging features of FXTAS include T2 hyperintensities in the pons, insula and periventricular white matter as well as generalised brain and cerebellar atrophy. FXTAS is an under-recognised and misdiagnosed entity. In patients with unexplained tremor, ataxia and cognitive decline, the presence of middle cerebellar peduncle and/or corpus callosum splenium hyperintensity should raise suspicion of FXTAS. Diagnosis of FXTAS has important implications not only for the patient but also, through genetic counselling and testing, for future generations.

Improving Multiple Sclerosis Plaque Detection Using a Semiautomated Assistive Approach

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 <3 minutes. Neurologists indicated retrospective management alterations in 79% of comparative study pairs with newly detected lesion changes.

CONCLUSIONS

Using software that highlights changes between study pairs can improve lesion detection. Neurologist feedback indicated a likely impact on management.

Intracranial involvement by multiple myeloma

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.

Occult temporal lobe encephalocoele into the transverse sinus

In this article we present a case of an incidental encephalocoele protruding through a dural defect into the transverse sinus. Encephalocoeles are usually described as a herniation of the meninges and brain parenchyma through a bony defect of the cranium or base of skull. To our knowledge, there are only a few patients reported in the literature of occult encephalocoeles through dural defects. Our case study highlights that encephalocoele should be a differential diagnosis for a filling defect in this location.

MRI grading versus histology: predicting survival of World Health Organization grade II-IV astrocytomas

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 patient's course.