The Impact of Gadolinium Deposition on Radiology Practice: An International Survey of Radiologists

RATIONALE AND OBJECTIVES

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.

MATERIALS AND METHODS

An electronic survey querying radiologists' practices regarding gadolinium deposition was distributed by Radiopaedia.org from November-December 2015.

RESULTS

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.

CONCLUSION

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.

Perceptual training to improve hip fracture identification in conventional radiographs

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.

The evolution of cerebrovascular changes in Köhlmeier-Degos disease: An 11-year follow-up case report

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.

Morphologic patterns of noncontrast-enhancing tumor in glioblastoma correlate with IDH1 mutation status and patient survival

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.

Bilateral traumatic abducens nerve avulsion: A case series and literature review

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.

Global fit concept in revision hip arthroplasty for cementless press-fit femoral stems

A revision stem may be required after a femoral extended trochanteric osteotomy (ETO) is made during revision hip arthroplasty. The two main complications of straight cementless femoral stems are subsidence due to inadequate osteointegration and stress-shielding. We will describe an original revision method with ETO that uses a straight cementless stem. The goal of this method was to achieve the most extensive press-fit possible during stem implantation to improve the transmission of stresses to the bone and to prevent reduction in bone density. The intramedullary preparation was done after closure and fixation of the ETO, which allows impaction of the revision stem with metaphyseal and diaphyseal press-fit. We report encouraging results with preservation of periprosthetic bone stock and good osteointegration of these revision stems at the final follow-up. Pronounced sagittal curvature or large bone defects are contraindications for this technique.

Neuroradiologists Compared with Non-Neuroradiologists in the Detection of New Multiple Sclerosis Plaques

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.

Multiple myeloma of the spine

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.

Reliability of noncontrast-enhancing tumor as a biomarker of IDH1 mutation status in glioblastoma

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.

Spontaneous subdural haemorrhage due to meningioma in the post-partum setting

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.

Estimated or Measured GFR in Living Kidney Donors Work-up?

The value of estimated glomerular filtration rate (eGFR) in living kidney donors screening is unclear. A recently published web-based application derived from large cohorts, but not living donors, calculates the probability of a measured GFR (mGFR) lower than a determined threshold. Our objectives were to validate the clinical utility of this tool in a cohort of living donors and to test two other strategies based on chronic kidney disease epidemiology collaboration (CKD-EPI) and on MDRD-eGFR. GFR was measured using ⁵¹ Cr- ethylene-diamine tetraacetic acid urinary clearance in 311 potential living kidney donors (178 women, mean age 50 ± 11.6 years). The web-based tool was used to predict those with mGFR < 80 mL/min/1.73 m² . Inputs to the application were sex, age, ethnicity, and plasma creatinine. In our cohort, a web-based probability of mGFR <90 mL/min/1.73 m² higher than 2% had 100% sensitivity for detection of actual mGFR <80 mL/min/1.73 m² . The positive predictive value was 0.19. A CKD-EPI-eGFR threshold of 104 mL/min/1.73 m² and an MDRD-eGFR threshold of 100 mL/min/1.73 m² had 100% sensitivity to detect donors with actual mGFR <80 mL/min/1.73 m² . We obtained similar results in an external cohort of 354 living donors. We confirm the usefulness of the web-based application to identify potential donors who should benefit from GFR measurement.

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.