Frank Gaillard

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 patients course.

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.

Improving Multiple Sclerosis Plaque Detection Using a Semiautomated Assistive Approach

The authors evaluated and validated a semiautomated software platform to facilitate detection of new lesions and improved MS lesions. Two neuroradiologists retrospectively assessed 161 MR imaging comparison study pairs acquired between 2009 and 2011. More comparison study pairs with new lesions and improved lesions were recorded by using the software compared with original radiology reports. 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.

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.

Incidence and prognostic significance of non-enhancing cortical signal abnormality in glioblastoma

The presence of non‐enhancing cortical signal abnormality is useful for differentiating between glioblastoma and metastatic disease, but its significance has not been studied. We aimed to determine the incidence and prognostic implications of non‐enhancing cortical signal abnormality in glioblastomas.

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.

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.

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.

Distinguishing Neuroimaging Features in Patients Presenting with Visual Hallucinations

SUMMARY: 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.

Letter by Dixon et al Regarding Article, “A Randomized Trial of Social Media From Circulation”

We read with interest the article by Fox et al1 showing no significant increase in Circulation journal article views after social media promotion. The researchers randomized 243 articles to promotion on the journal’s Facebook and Twitter accounts (n=121) or no promotion (n=122). Median 30 day article views were not significantly different between the groups (409 versus 392; P =0.8). As radiologists with an interest in online education, we recently tracked article views for a journal publication before and after promoting it on social media and would like to briefly present our findings. …