An Automated Brain Metastasis Detection and Segmentation System from MRI with a Large Multi-Institutional Dataset

PURPOSE/OBJECTIVE(S)

Developments of automated systems for brain metastasis (BM) detection and segmentation from MRI for assisting early detection and stereotactic radiosurgery (SRS) have been reported but most based upon relatively small datasets from single institutes. This work aims to develop and evaluate a system using a large multi-institutional dataset, and to improve both identification of small/subtle BMs and segmentation accuracy of large BMs.

MATERIALS/METHODS

A 3D U-Net system was trained and evaluated to detect and segment intraparenchymal BMs with a size > 2mm using 1856 MRI volumes from 1791 patients treated with SRS from seven institutions (1539 volumes for training, 183 for validation, and 134 for testing). All patients had 3D post-Gd T1w MRI scans pre-SRS. Gross tumor volumes (GTVs) of BMs for SRS were curated by each institute first. Then, additional efforts were spent to create GTVs for the untreated and/or uncontoured BMs, including central reviews by two radiologists, to improve accuracy of ground truth. The training dataset was augmented with synthetic BMs of 3773 MRIs using a 3D generative pipeline. Our system consists of two U-Nets with one using small 3D patches dedicated for detecting small BMs and another using large 3D patches for segmenting large BMs, and a random-forest based fusion module for combining the two network outputs. The first U-Net was trained with 3D patches containing at least one BM < 0.1 cm3. For detection performance, we measured BM-level sensitivity and case-level false-positive (FP) rate. For segmentation performance, we measured BM-level Dice similarity coefficient (DSC) and 95-percentile Hausdorff distance (HD95). We also stratified performances based upon BM sizes.

RESULTS

For 739 BMs in the 134 testing cases, the overall lesion-level sensitivity was 0.870 with an average case-level FP of 1.34±1.92 (95% CI: 1.02-1.67). The sensitivity was >0.969 for the BMs >0.1 cm3, but dropped to 0.755 for the BMs < 0.1 cm3 (Table 1). The average DSC and HD95 for all detected BMs were 0.786 and 1.35mm. The worse performance for BMs > 20 cm3 was caused by a case with 83 cm3 GTV and artifacts in the MRI volume.

CONCLUSION

We achieved excellent detection sensitivity and segmentation accuracy for BMs > 0.1 cm3, and promising performance for small BMs (<0.1cm3) with a controlled FP rate using a large multi-institutional dataset. Clinical utility for assisting early detection and SRS planning will be investigated. Table 1: Per-lesion detection and segmentation performance stratified by individual BM size. N is the number of BMs in each category.

Single Ventricle Reconstruction III: Brain Connectome and Neurodevelopmental Outcomes: Design, Recruitment, and Technical Challenges of a Multicenter, Observational Neuroimaging Study

Patients with hypoplastic left heart syndrome who have been palliated with the Fontan procedure are at risk for adverse neurodevelopmental outcomes, lower quality of life, and reduced employability. We describe the methods (including quality assurance and quality control protocols) and challenges of a multi-center observational ancillary study, SVRIII (Single Ventricle Reconstruction Trial) Brain Connectome. Our original goal was to obtain advanced neuroimaging (Diffusion Tensor Imaging and Resting-BOLD) in 140 SVR III participants and 100 healthy controls for brain connectome analyses. Linear regression and mediation statistical methods will be used to analyze associations of brain connectome measures with neurocognitive measures and clinical risk factors. Initial recruitment challenges occurred that were related to difficulties with: (1) coordinating brain MRI for participants already undergoing extensive testing in the parent study, and (2) recruiting healthy control subjects. The COVID-19 pandemic negatively affected enrollment late in the study. Enrollment challenges were addressed by: (1) adding additional study sites, (2) increasing the frequency of meetings with site coordinators, and (3) developing additional healthy control recruitment strategies, including using research registries and advertising the study to community-based groups. Technical challenges that emerged early in the study were related to the acquisition, harmonization, and transfer of neuroimages. These hurdles were successfully overcome with protocol modifications and frequent site visits that involved human and synthetic phantoms.

Single Ventricle Reconstruction III: Brain Connectome and Neurodevelopmental Outcomes: Design, Recruitment, and Technical Challenges of a Multicenter, Observational Neuroimaging Study

Patients with hypoplastic left heart syndrome who have been palliated with the Fontan procedure are at risk for adverse neurodevelopmental outcomes, lower quality of life, and reduced employability. We describe the methods (including quality assurance and quality control protocols) and challenges of a multi-center observational ancillary study, SVRIII (Single Ventricle Reconstruction Trial) Brain Connectome. Our original goal was to obtain advanced neuroimaging (Diffusion Tensor Imaging and Resting-BOLD) in 140 SVR III participants and 100 healthy controls for brain connectome analyses. Linear regression and mediation statistical methods will be used to analyze associations of brain connectome measures with neurocognitive measures and clinical risk factors. Initial recruitment challenges occurred related to difficulties with: 1) coordinating brain MRI for participants already undergoing extensive testing in the parent study, and 2) recruiting healthy control subjects. The COVID-19 pandemic negatively affected enrollment late in the study. Enrollment challenges were addressed by 1) adding additional study sites, 2) increasing the frequency of meetings with site coordinators and 3) developing additional healthy control recruitment strategies, including using research registries and advertising the study to community-based groups. Technical challenges that emerged early in the study were related to the acquisition, harmonization, and transfer of neuroimages. These hurdles were successfully overcome with protocol modifications and frequent site visits that involved human and synthetic phantoms.

Trial registration number

ClinicalTrials.gov Registration Number: NCT02692443.

NIMG-21. INTERIM ANALYSIS OF A PHASE II STUDY OF MULTIPARAMETRIC MR-GUIDED HIGH-DOSE RESPONSE-ADAPTIVE RADIOTHERAPY WITH CONCURRENT TEMOZOLOMIDE IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA

BACKGROUND

Biologically-informed radiotherapy (RT) targeting an adversely prognostic hypercellular/hyperperfused imaging phenotype in patients with newly diagnosed glioblastoma (GBM) may improve outcomes by identifying emerging regions of treatment resistance associated with survival (OS), and is under investigation in an ongoing Phase II trial (NCT04574856) of individualized, response-adaptive RT.

METHODS

In this single-arm phase II study, patients with newly diagnosed GBM following resection undergo dose-intensified chemoradiation targeting the residual hypercellular (TVHCV, mean contralateral normal brain+2SD) and hyperperfused tumor volume (TVCBV, contralateral normal frontal grey matter+1SD) identified using high b-value diffusion-weighted and dynamic contrast-enhanced perfusion MRI. The combination of TVHCVCBV (TVHCVCBV) is treated to 50 Gy in 20 fractions (2.5 Gy/fraction), and following mid-RT reassessment, the persistent and developing TVHCVCBV is treated to 30 Gy in 10 fractions (3 Gy/fraction). The primary endpoint is improvement in OS, with planned interim safety analysis.

RESULTS

Since October 2020, 16 of 30 patients have been enrolled. Median age was 58 years (range, 29-75) and 69% were male. No patient underwent biopsy only, and 50% had gross total resection; 23% had MGMT methylated tumors. Median TVHCV/TVCBV was 6.9 cc (range, 1.9-42.8) pre-RT and 30% (range, 1-72%) was nonenhancing. By mid-RT, TVHCVCBV was reduced to 4.2 cc (range, 0.8-34.3) and 47% (range, 3-74%) was nonenhancing. The TVHCVCBV persisting from pre- to mid-RT was 2.3 cc (range, 0-24.2), with an additional 1.8 cc (range, 0.3-20.6) newly developing outside the initial region. All patients underwent adaptive replanning for boost without interruption. Planned interim analysis determined an acceptable rate of neurologic toxicity and safety to continue enrollment.

CONCLUSION

Individualized, response adaptive RT using an advanced imaging biomarker to assess emerging and especially non-enhancing regions of treatment resistance in patients with GBM is feasible, with short term safety in an early cohort and longer-term efficacy outcomes anticipated with ongoing accrual.

NEIM-08 A PHASE II STUDY OF MULTIPARAMETRIC MR-GUIDED HIGH DOSE ADAPTIVE RADIOTHERAPY WITH CONCURRENT TEMOZOLOMIDE IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA

BACKGROUND

Biologically-informed radiotherapy (RT) targeting an adversely prognostic hypercellular/hyperperfused imaging phenotype in patients with newly diagnosed glioblastoma (GBM) may improve outcomes by identifying emerging regions of treatment resistance associated with survival (OS), and is under investigation as a target for individualized, adaptive RT in an ongoing Phase II trial (NCT04574856).

METHODS

In this single-arm study, patients with newly diagnosed GBM following resection undergo dose-intensified chemoRT targeting the residual hypercellular (TV_HCV, mean contralateral normal brain+2SD) and hyperperfused tumor volume (TV_CBV, contralateral normal frontal grey matter+1SD) identified using high b-value diffusion-weighted and dynamic contrast-enhanced perfusion MRI. TV_HCV/TV_CBV is treated to 50 Gy in 20 fractions (2.5 Gy/fraction), and following mid-RT reassessment, the persistent and developing TV_HCV/TV_CBV is treated to 30 Gy in 10 fractions (3 Gy/fraction). The primary endpoint is improvement in OS, with planned interim safety analysis.

RESULTS

Since October 2020, 16 of 30 patients have been enrolled. Median age was 58 years (range, 29-75) and 69% were male. No patient underwent biopsy, and 50% had gross total resection; 23% had MGMT methylated tumors, and all except 2 were IDHwt. Median TV_HCV/TV_CBV was 6.9 cc (range, 1.9-42.8) pre-RT and 30% (range, 1-72%) was nonenhancing. By mid-RT, TV_HCV/TV_CBV was reduced to 4.2 cc (range, 0.8-34.3) and 47% (range, 3-74%) was nonenhancing. The TV_HCV/TV_CBV persisting from pre- to mid-RT was 2.3 cc (range, 0-24.2), with an additional 1.8 cc (range, 0.3-20.6) newly developing outside of the initial region. All patients underwent adaptive replanning for boost without interruption. Planned interim analysis determined an acceptable rate of neurologic toxicity and safety to continue enrollment.

CONCLUSION

Individualized, adaptive radiotherapy using an advanced imaging biomarker to assess emerging and especially non-enhancing regions of treatment resistance in patients with GBM is feasible, with short term safety in an early cohort and longer-term efficacy outcomes anticipated with ongoing accrual.

Levetiracetam Prophylaxis for Children Admitted With Traumatic Brain Injury

BACKGROUND

Prophylactic antiseizure medications (ASMs) for pediatric traumatic brain injury (TBI) are understudied. We evaluated clinical and radiographic features that inform prescription of ASMs for pediatric TBI. We hypothesized that despite a lack of evidence, levetiracetam is the preferred prophylactic ASM but that prophylaxis is inconsistently prescribed.

METHODS

This retrospective study assessed children admitted with TBI from January 1, 2017, to December 31, 2019. TBI severity was defined using Glasgow Coma Scale (GCS) scores. Two independent neuroradiologists reviewed initial head computed tomography and brain magnetic resonance imaging. Fisher exact tests and descriptive and regression analyses were conducted.

RESULTS

Among 167 children with TBI, 44 (26%) received ASM prophylaxis. All 44 (100%) received levetiracetam. Prophylaxis was more commonly prescribed for younger children, those with neurosurgical intervention, and abnormal neuroimaging (particularly intraparenchymal hematoma) (odds ratio = 10.3, confidence interval 1.8 to 58.9), or GCS ≤12. Six children (13.6%), all on ASM, developed early posttraumatic seizures (EPTSs). Of children with GCS ≤12, four of 17 (23.5%) on levetiracetam prophylaxis developed EPTSs, higher than the reported rate for phenytoin.

CONCLUSIONS

Although some studies suggest it may be inferior to phenytoin, levetiracetam was exclusively used for EPTS prophylaxis. Intraparenchymal hematoma >1 cm was the single neuroimaging feature associated with ASM prophylaxis regardless of the GCS score. Yet these trends are not equivalent to optimal evidence-based management. We still observed important variability in neuroimaging characteristics and TBI severity for children on prophylaxis. Thus, further study of ASM prophylaxis and prevention of pediatric EPTSs is warranted.

Survival Prediction Analysis in Glioblastoma With Diffusion Kurtosis Imaging

SIMPLE SUMMARY

Glioblastoma (GBM) is the most common and aggressive primary brain tumor. Diffusion kurtosis imaging (DKI) has characterized non-Gaussian diffusion behaviors in brain normal tissue and gliomas, but there are very limited efforts in investigating treatment responses of kurtosis in GBM. This study aimed to investigate whether any parameter derived from the DKI is a significant predictor of overall survival (OS). We found that the large mean, 80 and 90 percentile kurtosis values in the contrast enhanced gross tumor volume (Gd-GTV) on post-Gd T1-weighted images pre-RT were significantly associated with reduced OS. In the multivariate Cox model, the mean kurtosis Gd-GTV pre-RT after considering effects of age, extent of surgery, and methylation were significant predictors of OS. In addition, the 80 and 90 percentile kurtosis values in Gd-GTV post RT were significantly associated with progression free survival (PFS). The DKI model demonstrates the potential to predict outcomes in the patients with GBM.

PURPOSE

Non-Gaussian diffusion behaviors in gliomas have been characterized by diffusion kurtosis imaging (DKI). But there are very limited efforts in investigating the kurtosis in glioblastoma (GBM) and its prognostic and predictive values. This study aimed to investigate whether any of the diffusion kurtosis parameters derived from DKI is a significant predictor of overall survival.

METHODS AND MATERIALS

Thirty-three patients with GBM had pre-radiation therapy (RT) and mid-RT diffusion weighted (DW) images. Kurtosis and diffusion coefficient (DC) values in the contrast enhanced gross tumor volume (Gd-GTV) on post-Gd T1 weighted images pre-RT and mid-RT were calculated. Univariate and multivariate Cox models were used to evaluate the DKI parameters and clinical factors for prediction of OS and PFS.

RESULTS

The large mean kurtosis values in the Gd-GTV pre-RT were significantly associated with reduced OS (p = 0.02), but the values at mid-RT were not (p > 0.8). In the multivariate Cox model, the mean kurtosis in the Gd-GTV pre-RT (p = 0.009) was still a significant predictor of OS after adjusting effects of age, O6-Methylguanine-DNA Methyl transferase (MGMT) methylation and extent of resection. In Gd-GTV post-RT, 80 and 90 percentile kurtosis values were significant predictors (p ≤ 0.05) for progression free survival (PFS).

CONCLUSION

The DKI model demonstrates the potential to predict OS and PFS in the patients with GBM. Further development and histopathological validation of the DKI model will warrant its role in clinical management of GBM.

Microstructure Modeling of High b-Value Diffusion-Weighted Images in Glioblastoma

Apparent diffusion coefficient has limits to differentiate solid tumor from normal tissue or edema in glioblastoma (GBM). This study investigated a microstructure model (MSM) in GBM using a clinically available diffusion imaging technique. The MSM was modified to integrate with bi-polar diffusion gradient waveforms, and applied to 30 patients with newly diagnosed GBM. Diffusion-weighted (DW) images acquired on a 3 T scanner with b-values from 0 to 2500 s/mm² were fitted in volumes of interest (VOIs) of solid tumor to obtain the apparent restriction size of intracellular water (ARS), the fractional volume of intracellular water (V_in), and extracellular (D_ex) water diffusivity. The parameters in solid tumor were compared with those of other tissue types by Students’ t test. For comparison, DW images were fitted by conventional mono-exponential and bi-exponential models. ARS, D_ex, and V_in from the MSM in tumor VOIs were significantly greater than those in WM, GM, and edema (P values of .01–.001). ARS values in solid tumors (from 21.6 to 34.5 um) had absolutely no overlap with those in all other tissue types (from 0.9 to 3.5 um). V_in values showed a descending order from solid tumor (from 0.32 to 0.52) to WM, GM, and edema (from 0.05 to 0.25), consisting with the descending cellularity in these tissue types. The parameters from mono-exponential and bi-exponential models could not significantly differentiate solid tumor from all other tissue types, particularly from edema. Further development and histopathological validation of the MSM will warrant its role in clinical management of GBM.

Everolimus improves the efficacy of dasatinib in PDGFRα-driven glioma

Pediatric and adult high-grade gliomas (HGGs) frequently harbor PDGFRA alterations. We hypothesized that cotreatment with everolimus may improve the efficacy of dasatinib in PDGFRα-driven glioma through combinatorial synergism and increased tumor accumulation of dasatinib. We performed dose-response, synergism, P-glycoprotein inhibition, and pharmacokinetic studies in in vitro and in vivo human and mouse models of HGG. Six patients with recurrent PDGFRα-driven glioma were treated with dasatinib and everolimus. We found that dasatinib effectively inhibited the proliferation of mouse and human primary HGG cells with a variety of PDGFRA alterations. Dasatinib exhibited synergy with everolimus in the treatment of HGG cells at low nanomolar concentrations of both agents, with a reduction in mTOR signaling that persisted after dasatinib treatment alone. Prolonged exposure to everolimus significantly improved the CNS retention of dasatinib and extended the survival of PPK tumor-bearing mice (mutant TP53, mutant PDGFRA, H3K27M). Six pediatric patients with glioma tolerated this combination without significant adverse events, and 4 patients with recurrent disease (n = 4) had a median overall survival of 8.5 months. Our results show that the efficacy of dasatinib treatment of PDGFRα-driven HGG was enhanced with everolimus and suggest a promising route for improving targeted therapy for this patient population.

DCE-MRI Evaluation of 10 patients with brain metastases treated with RRx-001, a Myc inhibitor and a CD47 and PD-L1 downregulator, in a phase I/II trial called BRAINSTORM

e14509

Background: In a Phase 1/2 trial called BRAINSTORM (NCT02215512) for brain metastases from any histology, quantitative changes in perfusion MRI after administration of RRx-001, a mic inhibitor and CD47 and PD-L1 downregulator with vascular normalizing properties, were determined and correlated with response. Methods: Ten patients with 64 total lesions evaluable at baseline, 24 hours, and end of radiotherapy (RT) that participated in BRAINSTORM were subjected to a correlative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) examination four days prior to the start of whole brain radiotherapy (WBRT) that evaluated Ktrans (capillary permeability) and Vp (plasma volume). The treatment comprised RRx-001 on Day -4, pre-WBRT then twice weekly during WBRT. Four dose levels were administered (5 mg/m2, 8.4 mg/m2, 16.5 mg/m2, and 27.5 mg/m2. Results: 10 patients underwent DCE-MRI scans and eight patients with 44 total evaluable lesions had available imaging at 1 month, and 6 patients with 29 total evaluable lesions had imaging at 4 months. On univariate analysis, only a decrease in 24-hour Vp from baseline after a single dose of RRx-001 was marginally associated with absolute tumor volume response 1 month after treatment (p-0.07). In a multivariate model, only Vp prior to therapy and 24-hour change in Vp were retained in the model after stepwise selection. A reduction in Vp 24 hours after RRx-001 (prior to WBRT) was associated with reduced tumor volume at 1 month (Estimate 0.88, 95% CI 0.37-1.40, p = 0.001) and 4 months (Estimate 1.51, 95% CI 0.58-2.43, p = 0.003). Likewise, a lower Vp prior to therapy was associated with reduced tumor volume at 1 month (Estimate 0.73, 95% CI 0.29-1.17, p = 0.002) and 4 months (Estimate 1.8, 95% CI 0.95-2.65, p = 0.0002), suggesting anti-angiogenic activity and early potential vascular normalization after a single dose of RRx-001 predictive of longer-term tumor response. Conclusions: RRx-001 induced a reduction in blood plasma volume, which was associated with tumor response and which suggests a vascular normalizing effect that merits further investigation in future planned studies. Clinical trial information: NCT02215512.

NIMG-77. RESPONSE ASSESSMENT USING MULTIPARAMETRIC MRI DURING CHEMORADIATION PREDICTS OVERALL SURVIVAL IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA

INTRODUCTION

Identifying both aggressive hypercellular (HCV) and hyperperfused (hCBV) regions of glioblastoma (GBM) prior to radiation (RT) using multiparametric MRI (mpMRI) predicts PFS and recurrence better than either technique alone, and is under investigation in a phase II trial as a novel target for dose-intensified RT. We hypothesized that early response in combined HCV/hCBV could be assessed using mpMRI and predict OS better than baseline assessment.

METHODS

Forty-three patients with newly diagnosed GBM underwent prospective high b-value (b=3000 s/mm2) DW-MRI and DCE-MRI pre-RT and 3 weeks into RT. Twenty patients were treated on a dose-escalation trial specifically targeting HCV/hCBV identified by mpMRI. An automated threshold method was used to generate HCV (mean contralateral normal brain+2SD) and hCBV (contralateral normal frontal grey matter+1SD). Survival was calculated using Kaplan-Meier method and compared using log-rank test. Age, gender, performance status, RT dose, extent of surgery, MGMT methylation, and imaging characteristic were tested in Cox proportional hazards models for survival.

RESULTS

Most patients had gross total (47%) or subtotal resection (37%), and 25% were MGMT methylated. Significant volumetric reduction during RT was observed in the Gd-enhanced volume (4.4 cc reduction, 95%CI 1.1–7.7, 17%), as well as HCV (1.8 cc reduction, 95%CI 0.2–3.4, 19%) and hCBV (1.1 cc reduction, 95%CI -0.4–2.6, 10%). No difference was observed between MGMT subgroups, but patients treated on protocol specifically targeting the mpMRI volume had significant reduction in combined HCV/hCBV (-4.4 cc, 95%CI -6.6,-2.3) vs non-protocol patients (-0.3 cc, 95%CI -2.6,2.0, p=0.006). A reduction in combined HCV/hCBV was associated with superior OS (AHR 0.60, 95%CI 0.40–0.89, p=0.01), while baseline imaging (all p< 0.90) and change in Gd-enhanced volume (p=0.61) were not.

CONCLUSIONS

Significant early response in HCV/hCBV during treatment is observed when targeted with dose-intensified RT, and is associated with improved OS with potential for adaptive strategies in future trials.

TRLS-07. BRAINSTORM: OUTCOMES FROM A MULTI-INSTITUTIONAL PHASE I/II STUDY OF RRx-001 IN COMBINATION WITH WHOLE BRAIN RADIATION THERAPY FOR PATIENTS WITH BRAIN METASTASES

INTRODUCTION: To determine the recommended Phase II dose of RRx-001, a radiosensitizer with vascular normalizing properties, when used with whole-brain radiation therapy (WBRT) for brain metastases, and to assess whether quantitative changes in perfusion MRI after RRx-001 correlate with response. METHODS AND MATERIALS: Five centers participated in this phase I/II trial of RRx-001 given once pre-WBRT then twice weekly during WBRT (30 Gy/10 fractions). Four dose levels were planned (5 mg/m2, 8.4 mg/m2, 16.5 mg/m2, 27.5 mg/m2). Dose-escalation was managed by the Time-to-Event Continual Reassessment Model (TITE-CRM). Correlative DCE-MRI was performed in a subset of patients and linear mixed models used to correlate change in 24-hour T1, Ktrans (capillary permeability) and Vp (plasma volume) with change in tumor volume. RESULTS: Between 2015–2017, 31 patients were enrolled. Two patients dropped out prior to any therapy and 7 were treated with concurrent temozolomide following a study amendment. Median age was 60 years (range, 30–76) and 17 were male. The most common tumor types were melanoma (58%) and non-small cell lung cancer (20%). No dose-limiting toxicities were observed. The most common severe adverse event was grade 3 asthenia in 6.9% (2/29). The median intracranial response rate was 46% (95%CI 24–68) and median overall survival was 5.2 months (95%CI 4.5–9.4). No neurologic deaths occurred. Among 10 evaluable patients undergoing DCE-MRI, a reduction in Vp 24 hours after RRx-001 was associated with reduced tumor volume at 1 month and 4 months (p≤0.01). CONCLUSION: The addition of RRx-001 to WBRT is safe and well-tolerated with favorable intracranial response rates. Because activity was observed across all dose levels, and in the absence of a dose response, the recommended Phase 2 dose is 10 mg administered twice weekly. A reduction in Vp by DCE-MRI 24 hours after RRx-001 suggests anti-angiogenic activity that is associated with longer-term tumor response.

An Introductory, Computer-Based Learning Module for Interpreting Noncontrast Head Computed Tomography

INTRODUCTION

New radiology and other residents must quickly assimilate a vast amount of anatomic and pathologic information when learning to interpret noncontrast head computed tomography (CT). No interactive, computer-based module using a search-pattern approach to provide new residents with the groundwork for interpretation of noncontrast head CT previously existed.

METHODS

We developed such a learning module using PowerPoint. First-year radiology residents completed the module prior to their neuroradiology rotation, and neurology residents completed it during orientation. Residents took 20-question pre- and posttests to assess knowledge and a postmodule survey. Each resident was randomized to one of two pretests and took the opposite as the posttest. Scores were collected over 5 years for radiology residents and 4 years for neurology residents. Statistical analysis of scores was performed using t tests.

RESULTS

Forty-seven first-year radiology residents and 31 neurology residents completed the module and the pre- and posttests. Scores for all residents either stayed the same or increased, regardless of the order of the versions of the pre- or posttests; the mean score increase was 4 (p < .0001) out of 20. Radiology residents had higher mean scores than neurology residents on the pre- and posttests, which were statistically significant (p < .04 and .0004, respectively). Feedback on the survey was overwhelmingly positive.

DISCUSSION

This computerized learning module is effective for teaching basic interpretation skills to new radiology and neurology residents. The module allows for asynchronous, programmed learning and the use of a step-by-step search-pattern approach.

Effects of an artificial placenta on brain development and injury in premature lambs

PURPOSE

We evaluated whether brain development continues and brain injury is prevented during Artificial Placenta (AP) support utilizing extracorporeal life support (ECLS).

METHODS

Lambs at EGA 118days (term=145; n=4) were placed on AP support (venovenous ECLS with jugular drainage and umbilical vein reinfusion) for 7days and sacrificed. Early (EGA 118; n=4) and late (EGA 127; n=4) mechanical ventilation (MV) lambs underwent conventional MV for up to 48h and were sacrificed, and early (n=5) and late (n=5) tissue control (TC) lambs were sacrificed at delivery. Brains were harvested, formalin-fixed, rehydrated, and studied by magnetic resonance imaging (MRI). The gyrification index (GI), a measure of cerebral folding complexity, was calculated for each brain. Diffusion-weighted imaging was used to determine fractional anisotropy (FA) and apparent diffusion coefficient (ADC) in multiple structures to assess white matter (WM) integrity.

RESULTS

No intracranial hemorrhage was observed. GI was similar between AP and TC groups. ADC and FA did not differ between AP and late TC groups in any structure. Compared to late MV brains, AP brains demonstrated significantly higher ADC (0.45±0.08 vs. 0.27±0.11, p=0.02) and FA (0.61±0.04 vs. 0.44±0.05; p=0.006) in the cerebral peduncles.

CONCLUSIONS

After 7days of AP support, WM integrity is preserved relative to mechanical ventilation.

TYPE OF STUDY

Research study.

Magnetic resonance imaging in patients with cardiac implanted electronic devices: focus on contraindications to magnetic resonance imaging protocols

Aims

Magnetic resonance imaging (MRI) has been reported to be safe in patients with cardiac implantable electronic devices (CIED) provided a specific protocol is followed. The objective of this study was to assess whether this is also true for patients excluded from published protocols.

Methods and results

A total of 160 MRIs were obtained in 142 consecutive patients with CIEDs [106 patients had an implantable cardioverter defibrillator (ICD) and 36 had a pacemaker implanted] using an adapted, pre-specified protocol. A cardiac MRI was performed in 95 patients, and a spinal/brain MRI was performed in 47 patients. Forty-six patients (32%) had either abandoned leads (n = 10), and/or were pacemaker dependent with an implanted ICD (n = 19), had recently implanted CIEDs (n = 1), and/or had a CIED device with battery depletion (n = 2), and/or a component of the CIED was recalled or on advisory (n = 32). No major complications occurred. Some device parameters changed slightly, but significantly, right after or at 1-week post-MRI without requiring any reprogramming. In one patient with an ICD on advisory, the pacing rate changed inexplicably during one of his two MRIs from 90 to 50 b.p.m.

Conclusion

Using a pre-specified protocol, cardiac and non-cardiac MRIs were performed in CIED patients with pacemaker dependency, abandoned leads, or depleted batteries without occurrence of major adverse events. Patients with devices on advisory need to be monitored carefully during MRI, especially if they are pacemaker dependent.

Mechanochemical synthesis of high coercivity Nd2(Fe,Co)14B magnetic particles

With increasing demand for magnets in energy conversion systems, the quest for the development and understanding of novel processing routes to produce permanent magnets has become urgent. We report a novel mechanochemical process for the synthesis of Nd₂(Fe,Co)₁₄B magnetic particles with a high coercivity of 12.4 kOe. This process involves the reduction of neodymium oxide, iron oxide, cobalt oxide and boron anhydride in the presence of a calcium reducing agent and a CaO diluent. The formation mechanism of Nd₂(Fe,Co)₁₄B changed with increasing CaO content, and the average crystal size of the Nd₂(Fe,Co)₁₄B particles also increased, resulting in an increase in the coercivity values. The reaction mechanism during milling was revealed through a study of the phase transformations as a function of milling time. It was found that unlike self-propagating reactions, this reduction reaction during milling requires continuous input of mechanical energy to reach a steady state.

Tumor image signatures and habitats: a processing pipeline of multimodality metabolic and physiological images

To create tumor "habitats" from the "signatures" discovered from multimodality metabolic and physiological images, we developed a framework of a processing pipeline. The processing pipeline consists of six major steps: (1) creating superpixels as a spatial unit in a tumor volume; (2) forming a data matrix [Formula: see text] containing all multimodality image parameters at superpixels; (3) forming and clustering a covariance or correlation matrix [Formula: see text] of the image parameters to discover major image "signatures;" (4) clustering the superpixels and organizing the parameter order of the [Formula: see text] matrix according to the one found in step 3; (5) creating "habitats" in the image space from the superpixels associated with the "signatures;" and (6) pooling and clustering a matrix consisting of correlation coefficients of each pair of image parameters from all patients to discover subgroup patterns of the tumors. The pipeline was applied to a dataset of multimodality images in glioblastoma (GBM) first, which consisted of 10 image parameters. Three major image "signatures" were identified. The three major "habitats" plus their overlaps were created. To test generalizability of the processing pipeline, a second image dataset from GBM, acquired on the scanners different from the first one, was processed. Also, to demonstrate the clinical association of image-defined "signatures" and "habitats," the patterns of recurrence of the patients were analyzed together with image parameters acquired prechemoradiation therapy. An association of the recurrence patterns with image-defined "signatures" and "habitats" was revealed. These image-defined "signatures" and "habitats" can be used to guide stereotactic tissue biopsy for genetic and mutation status analysis and to analyze for prediction of treatment outcomes, e.g., patterns of failure.

Posterior Fossa Hypervascular Tumour Embolisation

Hemangioblastomas are histologically benign tumours that comprise 7–12% of all posterior fossa lesions. Treatment of these lesions is often complicated by the significant vascularity of the tumour and the difficult surgical resection in the sensitive neural tissue. In such situations, preoperative embolisation facilitates surgery by not only decreasing the intraoperative blood loss, but also by decreasing the total operative time and allowing a near complete resection of the tumour. Though infrequent, fatal complications can occur during preoperative embolisation procedures. We report two such cases in which the tumour bled during the procedure. In both cases, this was effectively managed by arterial pedicle occlusion with NBCA (N-Butyl Cyano acrylate). The early detection, immediate control and the possible causes of this complication is presented.

Whole Brain Radiotherapy and RRx-001: Two Partial Responses in Radioresistant Melanoma Brain Metastases from a Phase I/II Clinical Trial: A TITE-CRM Phase I/II Clinical Trial

BACKGROUND: Kim et al. report two patients with melanoma metastases to the brain that responded to treatment with RRx-001 and whole brain radiotherapy (WBRT) without neurologic or systemic toxicity in the context of a phase I/II clinical trial. RRx-001 is an reactive oxygen and reactive nitrogen species (ROS/RNS)-dependent systemically nontoxic hypoxic cell radiosensitizer with vascular normalizing properties under investigation in patients with various solid tumors including those with brain metastases. SIGNIFICANCE: Metastatic melanoma to the brain is historically associated with poor outcomes and a median survival of 4 to 5 months. WBRT is a mainstay of treatment for patients with multiple brain metastases, but no significant therapeutic advances for these patients have been described in the literature. To date, candidate radiosensitizing agents have failed to demonstrate a survival benefit in patients with brain metastases, and in particular, no agent has demonstrated improved outcome in patients with metastatic melanoma. Kim et al. report two patients with melanoma metastases to the brain that responded to treatment with novel radiosensitizing agent RRx-001 and WBRT without neurologic or systemic toxicity in the context of a phase I/II clinical trial.

Clinical significance of small airway obstruction markers in patients with asthma

BACKGROUND

The role of small airway obstruction in the clinical expression of asthma is incompletely understood.

OBJECTIVE

We tested the hypotheses that markers of small airway obstruction are associated with (i) increased asthma severity, (ii) impaired asthma control and quality of life and (iii) frequent exacerbations.

METHODS

Seventy-four adults with asthma and 18 healthy control subjects underwent impulse oscillometry (IOS), multiple breath inert gas washout (MBW), body plethysmography, single-breath determination of carbon monoxide uptake and spirometry. Patients completed the six-point Asthma Control Questionnaire (ACQ-6) and standardized Asthma Quality of Life Questionnaire [AQLQ(S)]. Asthma severity was classified according to the Global Initiative for Asthma (GINA) treatment steps.

RESULTS

The putative small airway obstruction markers Sacin , resistance at 5 Hz minus resistance at 20 Hz (R5-R20) and reactance area (AX) were not independently associated with asthma severity, control, quality of life or exacerbations. In contrast, markers of total (R5) and mean airway resistance of large and small airways (R20) were significantly higher in the severe asthma group compared with the mild-moderate group (0.47 vs. 0.37, P < 0.05 for R5; 0.39 vs. 0.31, P < 0.01 for R20). The strongest independent contributors to ACQ-6 score were R20 and forced expiratory volume in one second (% pred.), and the strongest independent contributors to AQLQ(S) score were R20 and forced vital capacity (% pred.). A history of one or more exacerbations within the previous year was independently associated with R20.

CONCLUSIONS AND CLINICAL RELEVANCE

Previously reported markers of small airway obstruction do not appear to be independently associated with asthma disease expression. In contrast, the IOS parameter R20, a marker of mean airway resistance of both large and small airways, appears to have independent clinical significance. These observations require confirmation in prospective longitudinal studies.

Raise the bar and lower the dose: current and future strategies for radiation dose reduction in head and neck imaging

SUMMARY

Technologic advances in CT have generated a dramatic increase in the number of CT studies, with a resultant increase in the radiation dose related to CT scanning. Such increase in radiation dose is becoming a concern for the radiology community, especially with increasing public awareness of the dose burden related to examinations. To cope with the increase in CT-related radiation exposure, it is becoming necessary to optimize CT imaging protocols and apply radiation dose reduction techniques to ensure the best imaging with the lowest radiation dose.

Abstract PD1-3: Ph1b study of the PI3K inhibitor GDC-0032 in combination with fulvestrant in patients with hormone receptor-positive advanced breast cancer

Background: GDC-0032 is a next-generation PI3K inhibitor with increased anti-tumor activity against PIK3CA mutant cancers. GDC-0032 is an orally bioavailable, potent, and selective inhibitor of Class I PI3K alpha, delta, and gamma isoforms, with 30-fold less inhibition of the PI3K beta isoform relative to the PI3K alpha isoform. Preclinical data show that GDC-0032 has enhanced activity against PI3K alpha isoform (PIK3CA) mutant breast cancer cell lines. Preclinical data also show enhanced antitumor activity when GDC-0032 is combined with fulvestrant.

Material and Methods: A Phase 1b dose escalation study was conducted with evaluation of GDC-0032 doses ranging from 6-9 mg QD in combination with fulvestrant 500mg q4wk (with loading dose of 500mg at day 1, 14 and 28) in a modified 3+3 design. A dose expansion cohort was conducted at the recommended Phase 2 dose of 6 mg QD. Safety and tolerability of GDC-0032 was assessed, as well as pharmacokinetics (PK), pharmacodynamic (PD) assessment of PI3K pathway inhibition by paired tumor biopsies and by FDG-PET, and anti-tumor activity by RECIST.

Results: As of 1 Mar 2013, 17 patients were enrolled onto this study with the completion of dose escalation. No dose limiting toxicities (DLTs) were observed at either the 6 mg or 9 mg dose levels. Adverse events (AEs) assessed by the investigator as related to GDC-0032 in ≥10% of patients, were diarrhea, hyperglycemia, stomatitis, fatigue, asthenia, decreased appetite, nausea, mucosal inflammation and rash. No observed apparent PK interactions were observed between GDC-0032 and fulvestrant. The median number of prior systemic therapies was 6. Metabolic partial responses via FDG-PET (≥ 20% decrease in mSUVmax) were observed in 8 out of 11 patients assessed (73%). Confirmed partial responses by RECIST have been observed at both the 6mg and 9mg GDC-0032 dose levels. These include patients who have had prior treatment with fulvestrant. As of 29 May 2013, enrollment onto the dose escalation and expansion cohort has been completed (n = 27). Updated data on safety, pharmacodynamics, efficacy, and biomarker correlates will be presented.

Conclusions: The combination of GDC-0032 and fulvestrant is a well-tolerated regimen with promising preliminary efficacy. GDC-0032 is being further investigated in combination with fulvestrant for patients with hormone receptor-positive advanced breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD1-3.

Pediatric intracranial infections

Infection of the central nervous system (CNS) in children is an important entity and early recognition is paramount to avoid long-term brain injury, especially in very young patients. The causal factors are different in children compared with adults and so are the clinical presentations. However, imaging features of CNS infection show similar features to those of adults. This article reviews some of the common types of pediatric infections, starting with the congenital (or in utero) infections followed by bacterial infections of the meninges and brain parenchyma.

OCEANS: A randomized, double-blinded, placebo-controlled phase III trial of chemotherapy with or without bevacizumab (BEV) in patients with platinum-sensitive recurrent epithelial ovarian (EOC), primary peritoneal (PPC), or fallopian tube cancer (FTC)

LBA5007

Background: BEV, a humanized anti-VEGF monoclonal antibody, has shown a progression-free survival (PFS) benefit in 2 frontline phase III trials in patients with EOC, PPC and FTC. The therapeutic impact of BEV in combination with carboplatin (C) and gemcitabine (G) followed by single agent BEV to disease progression (PD) was evaluated in this phase III trial in the platinum-sensitive recurrent setting. Methods: Patients had recurrent, platinum-sensitive EOC, PPC or FTC, 1 prior regimen, no prior BEV, ECOG performance status 0-1, measurable disease. Subjects were randomized to: Arm A: [IV C (AUC 4, Day (D) 1) + G (1,000 mg/m2 D1 and 8) + placebo (PL) D1] q21D x 6 cycles (c) → PL q21D until PD or unacceptable toxicity (tox) Arm B: [CG + BEV (15 mg/kg) D1] q21D x 6 c → BEV q21D until PD or tox primary endpoint was investigator assessed PFS (RECIST). Secondary endpoints included objective response (OR), overall survival (OS), duration of response and safety. The design provided 80% power to detect a 27% reduction in the hazard of progression or death in Arm B vs A, limiting the overall type I error of 5%. Results: OCEANS enrolled 484 patients (242 per arm) from 4/07 - 1/10, median follow up of 24 months. BEV plus CG followed by single agent BEV to PD significantly increased PFS compared to CG alone (HR=0.484, p<0.0001). OR increased by 21% (p<0.0001). OS data is immature with only 29% of patients having had an event. The safety profile was consistent with other BEV trials. Conclusions: Results show a statistically significant and clinically relevant benefit when bevacizumab is added to chemotherapy in patients with recurrent, platinum sensitive EOC, PPC, and FTC. This is the first phase III trial of an antiangiogenic to demonstrate a clinical benefit to these patients.

[Table: see text]

Imaging of focal amyloid depositions in the head, neck, and spine: amyloidoma

Amyloidomas are benign tumorlike lesions consisting of localized deposits of amyloid and are the rarest form in the group of amyloidosis-related lesions. Diagnosis requires special stains; therefore, a high degree of suspicion for this disease is required. In this review, we describe the imaging features of amyloidomas involving the intracranial compartment, head and neck, and spine. We also discuss the differential diagnosis and briefly review the pertinent literature.

SABRE-B: an evaluation of paclitaxel and bevacizumab with or without sunitinib as first-line treatment of metastatic breast cancer

BACKGROUND

The vascular endothelial growth factor (VEGF) pathway can be targeted through VEGF neutralization or VEGF receptor (VEGFR) blockade using tyrosine kinase inhibition. Because laboratory models suggest that combining these approaches might be synergistic, we sought to evaluate the feasibility and efficacy of combining sunitinib with paclitaxel + bevacizumab (PB).

METHODS

Patients with human epidermal growth factor receptor 2 (HER2)-negative, metastatic breast cancer receiving first-line chemotherapy were randomized to PB or PB with sunitinib (PBS), with planned escalation of the sunitinib dose.

RESULTS

Forty-six patients were randomized to PB or PBS with sunitinib dosed at 25 mg p.o. daily. Patients receiving PBS encountered substantial toxicity that precluded adequate treatment. The percentage of patients with grade ≥3 adverse events was greater in the PBS arm than the PB arm (83% versus 57%), and sunitinib dosing was modified in 78% of patients, most often due to neutropenia, febrile neutropenia, and fatigue. In addition, 44% of patients had sunitinib dose reduction to 12.5 mg, and 39% required discontinuation. Patients receiving PBS had more bevacizumab treatment interruptions and discontinuations because of toxicity. Median treatment duration was longer in the PB arm compared with the PBS arm (14.1 versus 11.1 weeks), reflecting early treatment discontinuation of PBS. Because of poor tolerability of the addition of sunitinib to PB, the planned sunitinib dose escalation was halted and the study accrual was terminated.

CONCLUSION

Adding sunitinib to standard doses of bevacizumab plus paclitaxel for metastatic breast cancer is not feasible. Different strategies will be required to evaluate whether there is additional clinical benefit to combining VEGF/VEGFR-targeted agents.

Imaging of the anterior skull base

This article briefly discusses the imaging approach to lesions of the anterior skull base. A brief review of normal anatomy and imaging techniques is followed by a discussion about common neoplastic and non-neoplastic pathologies involving this region.

Dynamic MRA with four-dimensional time-resolved angiography using keyhole at 3 tesla in head and neck vascular lesions

Conventional MRA provides inadequate visualization of the dynamic features of blood flow in vascular lesions of the head and neck. Four-dimensional time-resolved angiography using keyhole (4D-TRAK) is a new technique of performing contrast-enhanced MRA. By combining parallel imaging with sensitivity encoding (SENSE) with the keyhole imaging technique and a high field strength (3 T) magnet, we have been able to obtain detailed hemodynamic information similar to that obtained via catheter angiography with digital subtraction (DSA), but without the risks associated with ionizing radiation exposure, iodizing contrast agents, or catheterization itself.

Developmental venous anomaly with symptomatic thrombosis of the draining vein

Developmental venous anomalies (DVAs) are generally considered a benign and asymptomatic finding on CT and MR imaging. The authors report 2 cases of spontaneous thrombosis of the draining vein of a DVA depicted on CT and MR imaging. One patient presented with a nonhemorrhagic transient ischemia, which was successfully treated with anticoagulant therapy. The second patient presented with ischemia complicated by hemorrhagic conversion.

Extrathyroidal manifestations of thyroid disease: thyroid ophthalmopathy

Thyroid ophthalmopathy is a common autoimmune, inflammatory disease involving the orbit. Diagnosis is based on the clinical presentation and findings. Imaging, mainly CT and MR imaging, are helpful to reveal the extent of disease and degree of muscle enlargement and to evaluate for complications, such as optic nerve compression. This article reviews the basic pathology and pathophysiology of the disease and describes the extensive imaging findings on CT and MR imaging. The differential diagnosis of thyroid ophthalmopathy is reviewed.

Giant tumefactive perivascular spaces

We describe the imaging characteristics of giant tumefactive perivascular spaces in a 37-year-old man who initially presented at the age of twenty years with vision change and headache and was found to have probable low grade neoplasm. The patient was followed subsequently at 8 years and 17 years later at our institution with stable imaging and neurologic exam. Magnetic resonance imaging demonstrated multiple cystic mass in the right frontal lobe which was stable in size and appearance. The mass followed signal intensity identical to cerebrospinal fluid on all sequences and was consistent with a giant tumefactive perivascular space. This report illustrates the need to keep this entity in mind when imaging evaluation demonstrates a lesion isointense to cerebrospinal fluid on all sequences. These lesions can actually be quite large and ominous appearing and many proceed to biopsy unnecessarily.

Conventional and diffusion-weighted MRI findings of methotrexate related sub-acute neurotoxicity

We describe longitudinal diffusion-weighted MRI findings of sub-acute leukoencephalopathy following methotrexate therapy in a 24-year-old man diagnosed with pre-B-cell acute lymphoblastic leukemia (ALL), presenting with right-sided paralysis and aphasia after second consolidation with intrathecal triple-drug therapy given intrathecally. This case demonstrates the value of DWI in evaluation and diagnosis of sub-acute toxic leukoencephalopathy in patients being treated with methotrexate. The longitudinal follow up DWI findings suggest reversible metabolic derangement rather than ischemia as the cause of these findings.

An unusual cause of recurrent pediatric neck abscess: pyriform sinus fistula

We present a case of recurrent anterior neck abscess due to a congenital fourth branchial anomaly. Pyriform fossa sinus is uncommon and poses a diagnostic and therapeutic challenge. This case reiterates that any child with a recurrent anterior neck mass should undergo thorough clinical and radiological assessments to rule out the possibility of a congenital sinus/fistula.

Imaging Nuances of Perineural Spread of Head and Neck Malignancies

Perineural spread is a common growth pattern of head and neck malignancies. Recognizing this pattern by imaging is important for two reasons: 1) it may be the only evidence of malignancy; and 2) its presence in conjunction with a mass converts management from surgical resection to radiation or chemotherapy. High field strength magnets and thin sections with high resolution and fat suppression now allow earlier diagnosis of this entity, but even with these imaging developments, familiarity with the relevant anatomy and the subtle alterations on MRI are necessary to identify this condition.