Periventricular nodular heterotopia associated with a "transmantle band sign" in patients with epilepsy.

OBJECTIVE: Previous studies using advanced magnetic resonance imaging (MRI) techniques have documented abnormal transmantle bands connecting ectopic nodules to overlying cortex in patients with periventricular nodular heterotopia (PNH). We describe a similar finding using conventional MRI techniques. METHODS: Patients were identified by means of a full-text search of radiological reports. All scanning was performed using conventional sequences at 3 Tesla (3T). Scans were reviewed by three neuroradiologists, and we characterized imaging features based on type of PNH and cortical irregularities associated with the transmantle band. RESULTS: A total 57 PNH patients were reviewed, of whom 41 demonstrated a "transmantle band" connecting the nodule to the overlying cortex. One or more periventricular heterotopic nodules was present in all 41 patients-this was bilateral in 29 of 41 (71%) and unilateral in the remaining 29%. In many cases there was more than one such band, and in some cases this band was nodular. In 19 of the cases, the cortex to which the band connected was abnormal, showing thinning in 4 cases, thickening in 5 cases, and polymicrogyria in another 10. SIGNIFICANCE: The transmantle band can be seen frequently in both unilateral and bilateral cases of PNH and can be visualized with conventional 3T MRI sequences. The band highlights the underlying neuronal migration issues at play in the pathogenesis of this disorder, but its underlying role in the complex, patient-specific epileptogenic networks in this cohort has yet to be determined and warrants further investigation.

Simultaneous multi-slice spin- and gradient-echo dynamic susceptibility-contrast perfusion-weighted MRI of gliomas.

Although combined spin- and gradient-echo (SAGE) dynamic susceptibility-contrast (DSC) MRI can provide perfusion quantification that is sensitive to both macrovessels and microvessels while correcting for T1 -shortening effects, spatial coverage is often limited in order to maintain a high temporal resolution for DSC quantification. In this work, we combined a SAGE echo-planar imaging (EPI) sequence with simultaneous multi-slice (SMS) excitation and blipped controlled aliasing in parallel imaging (blipped CAIPI) at 3 T to achieve both high temporal resolution and whole brain coverage. Two protocols using this sequence with multi-band (MB) acceleration factors of 2 and 3 were evaluated in 20 patients with treated gliomas to determine the optimal scan parameters for clinical use. ΔR2 *(t) and ΔR2 (t) curves were derived to calculate dynamic signal-to-noise ratio (dSNR), ΔR2 *- and ΔR2 -based relative cerebral blood volume (rCBV), and mean vessel diameter (mVD) for each voxel. The resulting SAGE DSC images acquired using MB acceleration of 3 versus 2 appeared visually similar in terms of image distortion and contrast. The difference in the mean dSNR from normal-appearing white matter (NAWM) and that in the mean dSNR between NAWM and normal-appearing gray matter were not statistically significant between the two protocols. ΔR2 *- and ΔR2 -rCBV maps and mVD maps provided unique contrast and spatial heterogeneity within tumors.

The centrally restricted diffusion sign on MRI for assessment of radiation necrosis in metastases treated with stereotactic radiosurgery.

PURPOSE: Differentiation of radiation necrosis from tumor progression in brain metastases treated with stereotactic radiosurgery (SRS) is challenging. For this, we assessed the performance of the centrally restricted diffusion sign. METHODS: Patients with brain metastases treated with SRS who underwent a subsequent intervention (biopsy/resection) for a ring-enhancing lesion on preoperative MRI between 2000 and 2020 were included. Excluded were lesions containing increased susceptibility limiting assessment of DWI. Two neuroradiologists classified the location of the diffusion restriction with respect to the post-contrast T1 images as centrally within the ring-enhancement (the centrally restricted diffusion sign), peripherally correlating to the rim of contrast enhancement, both locations, or none. Measures of diagnostic accuracy and 95% CI were calculated for the centrally restricted diffusion sign. Cohen's kappa was calculated to identify the interobserver agreement. RESULTS: Fifty-nine patients (36 female; mean age 59, range 40 to 80) were included, 36 with tumor progression and 23 with radiation necrosis based on histopathology. Primary tumors included 34 lung, 12 breast, 5 melanoma, 3 colorectal, 2 esophagus, 1 head and neck, 1 endometrium, and 1 thyroid. The centrally restricted diffusion sign was seen in 19/23 radiation necrosis cases (sensitivity 83% (95% CI 63 to 93%), specificity 64% (95% CI 48 to 78%), PPV 59% (95% CI 42 to 74%), NPV 85% (95% CI 68 to 94%)) and 13/36 tumor progression cases (difference p < 0.001). Interobserver agreement was substantial, at 0.61 (95% CI 0.45 to 70.8). CONCLUSION: We found a low probability of radiation necrosis in the absence of the centrally restricted diffusion sign.

Treatment-induced lesions in newly diagnosed glioblastoma patients undergoing chemoradiotherapy and heat-shock protein vaccine therapy.

OBJECTIVES: Treatment-induced lesions represent a great challenge in neuro-oncology. The aims of this study were (i) to characterize treatment induced lesions in glioblastoma patients treated with chemoradiotherapy and heat-shock protein (HSP) vaccine and (ii) to evaluate the diagnostic accuracy of diffusion weighted imaging for differentiation between treatment-induced lesions and tumor progression. METHODS: Twenty-seven patients with newly diagnosed glioblastoma treated with HSP vaccine and chemoradiotherapy were included. Serial magnetic resonance imaging evaluation was performed to detect treatment-induced lesions and assess their growth. Quantitative analysis of the apparent diffusion coefficient (ADC) was performed to discriminate treatment-induced lesions from tumor progression. Mann-Whitney U-test and receiver operating characteristic (ROC) curves were used for analysis. RESULTS: Thirty-three percent of patients developed treatment-induced lesions. Five treatment-related lesions appeared between end of radiotherapy and the first vaccine administration; 4 lesions within the first 4 months from vaccine initiation and 1 at 3.5 years. Three patients with pathology proven treatment-induced lesions showed a biphasic growth pattern progressed shortly after. ADC ratio between the peripheral enhancing rim and central necrosis showed an accuracy of 0.84 (95% CI 0.63-1) for differentiation between progression and treatment-induced lesions. CONCLUSION: Our findings do not support the iRANO recommendation of a 6-month time window in which progressive disease should not be declared after immunotherapy initiation. A biphasic growth pattern of pathologically proven treatment-induced lesions was associated with a dismal prognosis. The presence of lower ADC values in the central necrotic portion of the lesions compared to the enhancing rim shows high specificity for detection of treatment-induced lesions.

Hypoxia Detection in Infiltrative Astrocytoma: Ferumoxytol-based Quantitative BOLD MRI with Intraoperative and Histologic Validation.

Purpose To validate ferumoxytol-based quantitative blood oxygenation level-dependent (BOLD) MRI for mapping oxygenation of human infiltrative astrocytomas by using intraoperative measurement of tissue oxygen tension and histologic staining. Materials and Methods Fifteen patients with infiltrative astrocytomas were recruited into this prospective multicenter study between July 2014 and December 2016. Prior to treatment, participants underwent preoperative quantitative BOLD MRI with ferumoxytol to generate tissue oxygen saturation (StO2) maps. Two intratumoral sites were identified, one with low StO2 and one with high StO2. Neuronavigation was used to locate sites intraoperatively for insertion of oxygen-sensing probes to measure local tissue oxygen tension (PtO2). Biopsies from both sites were taken and stained for markers of hypoxia (hypoxia-inducible factor 1α, carbonic anhydrase IX) and neoangiogenesis (vascular endothelial growth factor, endoglin [CD105]). Spearman correlation and nonparametric sign-rank tests were used to analyze data. Results Ten patients with median age of 58.5 years (interquartile range, 25 years; four men and six women) completed the study. Because there is no linear relationship between StO2 and PtO2, the ratios of low to high StO2 versus low to high PtO2 in each patient were compared and a significant correlation was found (r = 0.73; P = .01). Pathologic analyses revealed differences between carbonic anhydrase IX (P = .03) for sites of low StO2 versus high StO2. CD105 displayed a similar trend but was not significant (P = .09). Conclusion Ferumoxytol-based quantitative blood oxygenation level-dependent MRI can potentially be used as a noninvasive surrogate for oxygenation mapping in infiltrative astrocytomas. This technique can potentially be integrated in treatment planning for aggressive targeting of hypoxic areas in tumors.

Meta-analysis of timing of endovascular aneurysm treatment in subarachnoid haemorrhage: inconsistent results of early treatment within 1 day.

BACKGROUND AND PURPOSE: To systematically review and meta-analyse the data on impact of timing of endovascular treatment in aneurysmal subarachnoid haemorrhage (SAH) to determine if earlier treatment is associated with improved clinical outcomes and reduced case fatality. METHODS: We searched MEDLINE, Cochrane database, EMBASE and Web of Science to identify studies for inclusion. The measures of effect utilised were unadjusted/adjusted ORs. Effect estimates were combined using random effects models for each outcome (poor outcome, case fatality); heterogeneity was assessed using the I2 index. Subgroup and sensitivity analyses were performed to account for heterogeneity and risk of bias. RESULTS: 16 studies met the inclusion criteria. Treatment <1 day was associated with a reduced odds of poor outcome compared with treatment >1 day (OR=0.40 (95% CI 0.28 to 0.56; I2=0%)) but not when compared with treatment at 1-3 days (OR=1.16 (95% CI 0.47 to 2.90; I2=81%)). Treatment at <2 days and at <3 days were associated with similar odds of poor outcome compared with later treatment (OR=1.20 (95% CI 0.70 to 2.05; I2=73%; OR=0.71 (95% CI 0.36 to 1.37; I2=71%)). Early treatment was associated with similar odds of case fatality compared with later treatment, regardless of how early/late treatment were defined (OR=1.80 (95% CI 0.88 to 3.67; I2=34%) for treatment <1 day vs days 1-3; OR=1.71 (95% CI 0.72 to 4.03; I2=54%) for treatment <2 days vs later; OR=0.90 (95% CI 0.31 to 2.68; I2=48%) for treatment <3 days vs later). CONCLUSIONS: In only 1 of the analyses was there a statistically significant result, which favoured treatment <1 day. The inconsistent results and heterogeneity within most analyses highlight the lack of evidence for best timing of endovascular treatment in SAH patients.

Natural history of lesions with the MR imaging appearance of multinodular and vacuolating neuronal tumor.

PURPOSE: Multinodular and vacuolating neuronal tumor (MVNT) have been recently added to the WHO classification of CNS tumors and has not been extensively reported upon in the radiological literature. We report the first radiological and the largest series of cases, aiming to highlight the natural history of lesions with the imaging appearance of MVNT with long follow-up time. METHODS: In this retrospective study, we collected cases with the imaging appearance of MVNT. All lesions were evaluated by using routine MR imaging, with follow-up of up to 93 months. Patient demographics, clinical course, and MRI features of the lesions were recorded. RESULTS: Twenty-four subjects were enrolled, f/m = 16:8, age range 24-59 years, with a median age of 45 years. The patients' symptoms were often episodic and most frequently due to headaches in 12 (50%), visual symptoms in 6 (25%), seizures in 5 ± 1 (20-25%), paresthesia in 4 (~17%), cognitive difficulties in 4 (~17%), in addition to other variable neurological symptoms, or incidental. A total of 30 lesions identified, 77% of the lesions had gadolinium-enhanced MRI and only 13% showed enhancement. A 6.7% of the lesions that had MRI followed up showed progression, while the rest remained stable up to 93 months interval. All patients had intact neurological examinations (except one case that was diagnosed with optic neuritis), were managed conservatively, and did well. CONCLUSION: The natural history of lesions with imaging features of MVNT is overall stable from a clinical and imaging appearance over time.

Prominent Inferior Intercavernous Sinus on Sagittal T1-Weighted Images: A Sign of Intracranial Hypotension.

OBJECTIVE: The purpose of this study is to describe the diagnostic accuracy of the dilatation of the inferior intercavernous sinus as a sign of intracranial hypotension and to raise awareness of this anatomic structure, which can be mistaken for a focal pituitary lesion. MATERIALS AND METHODS: Sagittal T1-weighted images of 26 patients with intracranial hypotension and 28 control subjects were evaluated to determine the presence of a distended inferior intercavernous sinus. Information about the shape, size, and signal of the inferior intercavernous sinus was also collected. The chi-square test was used to compare both groups. Sensitivity and specificity of the dilatation of the inferior intercavernous sinus as a sign of intracranial hypotension were calculated. RESULTS: A visible inferior intercavernous sinus was found in 13 of 26 patients with intracranial hypotension (50%) and in four of 28 control subjects (14.3%). These percentages were significantly different (p = 0.005). There was no significant difference in size of the inferior intercavernous sinus in the intracranial hypotension group (median, 5.86 mm(2); interquartile range, 6.28 mm(2)) compared with the control group (median, 8.25 mm(2); interquartile range, 16.69 mm(2)). Changes in the size of the inferior intercavernous sinus were detected in congruence with the appearance or resolution of intracranial hypotension. CONCLUSION: Dilatation of the inferior intercavernous sinus is frequently associated with intracranial hypotension, although it can also be found in the healthy adult as a normal anatomic variant. Recognition of this anatomic structure is important to avoid mistaking it for a focal pituitary lesion.

Comparative Evaluation of Lower Gadolinium Doses for MR Imaging of Meningiomas: How Low Can We Go?

BACKGROUND AND PURPOSE: Gadolinium-based contrast agents are widely used for meningioma imaging; however, concerns exist regarding their side effects, cost, and environmental impact. At the standard gadolinium dose, most meningiomas show avid contrast enhancement suggesting that administering a smaller dose may be feasible. The purpose of this study was to evaluate the impact of a lower gadolinium dose on the differentiation between meningiomas and adjacent intracranial tissues. MATERIALS AND METHODS: 108 patients with presumed or confirmed meningiomas who underwent brain MRI at multiple doses of gadolinium were included in the study. The patients' MRIs were categorized into three groups based on the gadolinium dose administered: Micro (approximately 25% of the standard dose), Low (approximately 62% of the standard dose) and Standard dose. Multi-reader qualitative visual assessment and quantitative relative signal differences calculations were performed to evaluate tumor differentiation from the cortex and from the dural venous sinus. The relative signal differences for each dose were analyzed using ANOVA for quantitative assessment and NcNemar for qualitative assessment. Additionally, non-inferiority testing was used to compare the Low and Micro doses to the Standard dose. RESULTS: Decreasing the gadolinium dose to a Low dose or a Micro dose resulted in a statistically significant decrease in signal difference between the tumor and the adjacent brain tissues (p<0.02). However, on visual assessment, the Low dose was non-inferior to the Standard dose. The proportion of cases with suboptimal differentiation was significantly higher for the Micro dose than for the Standard dose, both for the differentiation between the tumor and the cortex (p=0.041) and the differentiation between tumor and sinus (p<0.001). CONCLUSIONS: Reducing the gadolinium dose to 62% of the standard level still allows for sufficient visual delineation of meningiomas from surrounding tissues. However, further reduction to 25% substantially compromises the ability to distinguish the tumor from adjacent structures and is, therefore, not advisable. ABBREVIATIONS: GBCAs = Gadolinium-based contrast agents; SSS = Superior Sagittal Sinus.

Comparison of clinically available dynamic susceptibility contrast post processing software to differentiate progression from pseudoprogression in post-treatment high grade glioma.

INTRODUCTION: The purpose of this retrospective study was to compare two, widely available software packages for calculation of Dynamic Susceptibility Contrast (DSC) perfusion MRI normalized relative Cerebral Blood Volume (rCBV) values to differentiate tumor progression from pseudoprogression in treated high-grade glioma patients. MATERIAL AND METHODS: rCBV maps processed by Siemens Syngo.via (Siemens Healthineers) and Olea Sphere (Olea Medical) software packages were co-registered to contrast-enhanced T1 (T1-CE). Regions of interest based on T1-CE were transferred to the rCBV maps. rCBV was calculated using mean values and normalized using contralateral normal- appearing white matter. The Wilcoxon test was performed to assess for significant differences, and software-specific optimal rCBV cutoff values were determined using the Youden index. Interrater reliability was evaluated for two raters using the intraclass correlation coefficient. RESULTS: 41 patients (18 females; median age = 59 years; range 21-77 years) with 49 new or size-increasing post-treatment contrast-enhancing lesions were included (tumor progression = 40 lesions; pseudoprogression = 9 lesions). Optimal rCBV cutoffs of 1.31 (Syngo.via) and 2.40 (Olea) were significantly different, with an AUC of 0.74 and 0.78, respectively. Interrater reliability was 0.85. DISCUSSION: We demonstrate that different clinically available MRI DSC-perfusion software packages generate significantly different rCBV cutoff values for the differentiation of tumor progression from pseudoprogression in standard-of-care treated high grade gliomas. Physicians may want to determine the unique value of their perfusion software packages on an institutional level in order to maximize diagnostic accuracy when faced with this clinical challenge. Furthermore, combined with implementation of current DSC-perfusion recommendations, multi-center comparability will be improved.

Quantitative spinal cord MRI and sexual dysfunction in multiple sclerosis.

Background: Sexual dysfunction (SD) is frequently reported in multiple sclerosis (MS) and is likely related to MS-related damage to the spinal cord (SC). Objective: To assess associations between SD and quantitative MRI measures in people with MS (pwMS). Methods: This pilot study included 17 pwMS with SD who completed questionnaires assessing SD, mood, and fatigue. All participants underwent brain, cervical, and thoracic SC-MRI at 3T. Quantitative brain and SC-MRI measures, including brain/SC atrophy, SC lesion count, diffusion-tensor imaging (DTI) indices (fractional anisotropy [FA], mean, perpendicular, parallel diffusivity [MD, λ⊥, λ||]) and magnetization-transfer ratio (MTR) were obtained. Associations between quantitative MRI measures and SD were assessed while controlling for the extent of mood and fatigue symptomatology. Results: Subjects were a mean age of 46.9 years and 29% female. All subjects had self-reported SD (MSISQ-19 = 40.7, SQoL: 55.9) and 65% had a concurrent psychiatric diagnosis. When correlations between SD severity were assessed with individual brain and SC-MRI measures while controlling for psychiatric symptomatology, no associations were found. The only variables showing independent associations with SD were anxiety (p = 0.03), depression (p = 0.05), and fatigue (p = 0.04). Conclusion: We found no correlations between quantitative MRI measures in the brain and SC and severity of SD in pwMS, but psychiatric symptomatology and fatigue severity demonstrated relationships with SD. The multifactorial nature of SD in pwMS mandates a multidisciplinary approach.

Progressive Supranuclear Palsy Syndrome Associated With a Novel Tauopathy: Case Study.

OBJECTIVES: To report a novel tauopathy in a patient with protracted coursed progressive supranuclear palsy (PC-PSP). METHODS: Clinical follow-up, gene analysis, neuropathological study. RESULTS: A 73-year-old man presented with diplopia, slowness, shuffling gait and falls. Neurological examination revealed slowed saccades, restricted up-gaze and mild parkinsonism. Three years after onset he developed personality changes. Slowly progressive parkinsonism was associated with memory and executive deficits. MRI showed subtle bilateral hippocampal and midbrain tegmentum atrophy and hyper-intensity in the brainstem tegmentum and white matter of the medial temporal lobe. Duration of illness was 11 years. There were no pathogenic mutations in 80 genes known to be involved in neurodegeneration, including MAPT (H1/H1 haplotype) and APOE (ε3/ε3 genotype). Neuropathology revealed PSP type pathology together with the pathology described in the novel limbic-predominant neuronal inclusion body 4-repeat tauopathy (LNT) correlating well with the signal alterations seen in MRI. DISCUSSION: Our observation broadens the spectrum of tau pathology associated with PC-PSP and suggests that memory deficit and hippocampal atrophy may be suggestive of non-Alzheimer's disease pathology, including LNT. Understanding the diverse range of tau morphologies may help explain phenotypic heterogeneity seen in PSP.

Gender Differences in Diagnostic Radiology Practice: An Observational Study.

PURPOSE: To investigate gender differences in diagnostic radiology practice, specifically, the differences in scope of practice, the frequency of consultations to other colleagues, and the error rates. MATERIAL AND METHODS: A retrospective observational study was performed including radiologists working for a European teleradiology provider between 2013 and 2019. Main outcome measures included the adjusted odds ratio of female gender for reporting cases in more than one subspecialty, the adjusted incidence rate ratio (IRR) of female gender for the count of second opinion requests to other colleagues, and the adjusted IRR of female gender for the count of radiologic errors. Multivariable adjustment was performed for covariates associated with experience, type of cases reported, part- or full-time employment, and reporting speed. RESULTS: A total of 213 radiologists (36% female) were included in the analysis of gender differences in scope of practice. Female gender was associated with a lower odds of reporting cases in more than one subspecialty with an odds ratio of 0.46 (95% confidence interval, 0.22-0.96). A total of 204 radiologists (36% female) were included in the analysis of gender differences in the count of second opinion requests to colleagues. There was a trend toward an association between female gender and higher odds of requesting a second opinion with an adjusted IRR of 1.6 compared with male gender, but it was not statistically significant (P = .08). A total of 199 radiologists were included (37% female) in the analysis of gender differences in the number of radiologic errors. Female gender was associated with a decrease in the odds of error with an IRR of 0.8 (95% confidence interval, 0.64-0.995). CONCLUSIONS: Female radiologists tend to have a narrower scope of practice and make fewer mistakes than their male counterparts, even after detailed adjustment for factors that might explain gender differences in scope of practice and errors.

Neuroimaging Pearls from the MDS Congress Video Challenge. Part 1: Genetic Disorders.

We selected several "imaging pearls" presented during the Movement Disorder Society (MDS) Video Challenge for this review. While the event, as implicated by its name, was video-centered, we would like to emphasize the important role of imaging in making the correct diagnosis. We divided this anthology into two parts: genetic and acquired disorders. Genetic cases described herein were organized by the inheritance pattern and the focus was put on the imaging findings and differential diagnoses. Despite the overlapping phenotypes, certain described disorders have pathognomonic MRI brain findings that would provide either the "spot" diagnosis or result in further investigations leading to the diagnosis. Despite this, the diagnosis is often challenging with a broad differential diagnosis, and hallmark findings may be present for only a limited time.

Improving the noninvasive classification of glioma genetic subtype with deep learning and diffusion-weighted imaging.

BACKGROUND: Diagnostic classification of diffuse gliomas now requires an assessment of molecular features, often including IDH-mutation and 1p19q-codeletion status. Because genetic testing requires an invasive process, an alternative noninvasive approach is attractive, particularly if resection is not recommended. The goal of this study was to evaluate the effects of training strategy and incorporation of biologically relevant images on predicting genetic subtypes with deep learning. METHODS: Our dataset consisted of 384 patients with newly diagnosed gliomas who underwent preoperative MRI with standard anatomical and diffusion-weighted imaging, and 147 patients from an external cohort with anatomical imaging. Using tissue samples acquired during surgery, each glioma was classified into IDH-wildtype (IDHwt), IDH-mutant/1p19q-noncodeleted (IDHmut-intact), and IDH-mutant/1p19q-codeleted (IDHmut-codel) subgroups. After optimizing training parameters, top performing convolutional neural network (CNN) classifiers were trained, validated, and tested using combinations of anatomical and diffusion MRI with either a 3-class or tiered structure. Generalization to an external cohort was assessed using anatomical imaging models. RESULTS: The best model used a 3-class CNN containing diffusion-weighted imaging as an input, achieving 85.7% (95% CI: [77.1, 100]) overall test accuracy and correctly classifying 95.2%, 88.9%, 60.0% of the IDHwt, IDHmut-intact, and IDHmut-codel tumors. In general, 3-class models outperformed tiered approaches by 13.5%-17.5%, and models that included diffusion-weighted imaging were 5%-8.8% more accurate than those that used only anatomical imaging. CONCLUSION: Training a classifier to predict both IDH-mutation and 1p19q-codeletion status outperformed a tiered structure that first predicted IDH-mutation, then 1p19q-codeletion. Including apparent diffusion coefficient (ADC), a surrogate marker of cellularity, more accurately captured differences between subgroups.

Pattern of Recurrence of Glioblastoma Versus Grade 4 IDH-Mutant Astrocytoma Following Chemoradiation: A Retrospective Matched-Cohort Analysis.

Background and Purpose: To quantitatively compare the recurrence patterns of glioblastoma (isocitrate dehydrogenase-wild type) versus grade 4 isocitrate dehydrogenase-mutant astrocytoma (wild type isocitrate dehydrogenase and mutant isocitrate dehydrogenase, respectively) following primary chemoradiation. Materials and Methods: A retrospective matched cohort of 22 wild type isocitrate dehydrogenase and 22 mutant isocitrate dehydrogenase patients were matched by sex, extent of resection, and corpus callosum involvement. The recurrent gross tumor volume was compared to the original gross tumor volume and clinical target volume contours from radiotherapy planning. Failure patterns were quantified by the incidence and volume of the recurrent gross tumor volume outside the gross tumor volume and clinical target volume, and positional differences of the recurrent gross tumor volume centroid from the gross tumor volume and clinical target volume. Results: The gross tumor volume was smaller for wild type isocitrate dehydrogenase patients compared to the mutant isocitrate dehydrogenase cohort (mean ± SD: 46.5 ± 26.0 cm3 vs 72.2 ± 45.4 cm3, P = .026). The recurrent gross tumor volume was 10.7 ± 26.9 cm3 and 46.9 ± 55.0 cm3 smaller than the gross tumor volume for the same groups (P = .018). The recurrent gross tumor volume extended outside the gross tumor volume in 22 (100%) and 15 (68%) (P= .009) of wild type isocitrate dehydrogenase and mutant isocitrate dehydrogenase patients, respectively; however, the volume of recurrent gross tumor volume outside the gross tumor volume was not significantly different (12.4 ± 16.1 cm3 vs 8.4 ± 14.2 cm3, P = .443). The recurrent gross tumor volume centroid was within 5.7 mm of the closest gross tumor volume edge for 21 (95%) and 22 (100%) of wild type isocitrate dehydrogenase and mutant isocitrate dehydrogenase patients, respectively. Conclusion: The recurrent gross tumor volume extended beyond the gross tumor volume less often in mutant isocitrate dehydrogenase patients possibly implying a differential response to chemoradiotherapy and suggesting isocitrate dehydrogenase status might be used to personalize radiotherapy. The results require validation in prospective randomized trials.

Neuroimaging Pearls from the MDS Congress Video Challenge. Part 2: Acquired Disorders.

The MDS Video Challenge continues to be the one of most widely attended sessions at the International Congress. Although the primary focus of this event is the presentation of complex and challenging cases through videos, a number of cases over the years have also presented an unusual or important neuroimaging finding related to the case. We reviewed the previous Video Challenge cases and present here a selection of those cases which incorporated such imaging findings. We have compiled these "imaging pearls" into two anthologies. The first focuses on pearls where the underlying diagnosis was a genetic condition. This second anthology focuses on imaging pearls in cases where the underlying condition was acquired. For each case we present brief clinical details along with neuroimaging findings, the characteristic imaging findings of that disorder and, finally, the differential diagnosis for the imaging findings seen.

Transformational Role of Medical Imaging in (Radiation) Oncology.

Onboard, real-time, imaging techniques, from the original megavoltage planar imaging devices, to the emerging combined MRI-Linear Accelerators, have brought a huge transformation in the ability to deliver targeted radiation therapies. Each generation of these technologies enables lethal doses of radiation to be delivered to target volumes with progressively more accuracy and thus allows shrinking of necessary geometric margins, leading to reduced toxicities. Alongside these improvements in treatment delivery, advances in medical imaging, e.g., PET, and MRI, have also allowed target volumes themselves to be better defined. The development of functional and molecular imaging is now driving a conceptually larger step transformation to both better understand the cancer target and disease to be treated, as well as how tumors respond to treatment. A biological description of the tumor microenvironment is now accepted as an essential component of how to personalize and adapt treatment. This applies not only to radiation oncology but extends widely in cancer management from surgical oncology planning and interventional radiology, to evaluation of targeted drug delivery efficacy in medical oncology/immunotherapy. Here, we will discuss the role and requirements of functional and metabolic imaging techniques in the context of brain tumors and metastases to reliably provide multi-parametric imaging biomarkers of the tumor microenvironment.