Kaufmann, Timothy J.

Objective: To compare progressive motor impairment onset attributable to a “critical” central nervous system (CNS) demyelinating lesion in patients with highly restricted versus unlimited magnetic resonance imaging (MRI) lesion burden. Methods: We identified 135 patients with progressive motor impairment for ⩾1 year attributable to a “critical” demyelinating lesion with: MRI burden of 1 lesion (“progressive solitary sclerosis”), 2–5 lesions (“progressive paucisclerosis”), or unrestricted (>5) lesions and “progressive unilateral hemiparesis.” Neuroradiology review of brain and spinal cord MRI documented unequivocally demyelinating lesions. Results: A total of 33 (24.4%) patients had progressive solitary sclerosis; 56 (41.5%) patients had progressive paucisclerosis; and 46 (34.1%) patients had progressive unilateral hemiparesis. Median age at onset of progressive motor impairment was younger in progressive solitary sclerosis (49 years; range 24–73) and progressive paucisclerosis (50 years; range 30–64) than in progressive unilateral hemiparesis (54 years; range 39–77; p = 0.02 and p = 0.003, respectively). Within progressive unilateral hemiparesis, motor-progression onset was similar between those with 4–10, 11–20, or >20 brain lesions (55, 54, 53 years of age, respectively; p = 0.44). Conclusion: Motor-progression age is similar, but paradoxically earlier, in cohorts with highly restricted CNS lesion burden than in those with unrestricted lesion burden with progressive unilateral hemiparetic MS. The “critical” demyelinating lesion rather than total brain MRI lesion burden is the major contributor to motor-progression onset in these cohorts.

The thalamic ventral intermediate nucleus (VIM) can be targeted for treatment of tremor by several procedures, including deep brain stimulation (DBS) and, more recently, MR-guided focused ultrasound (MRgFUS). To date, such targeting has relied predominantly on coordinate-based or atlas-based techniques rather than directly targeting the VIM based on imaging features. While general regional differences of features within the thalamus and some related white matter tracts can be distinguished with conventional imaging techniques, internal nuclei such as the VIM are not discretely visualized. Advanced imaging methods such as quantitative susceptibility mapping (QSM) and fast gray matter acquisition T1 inversion recovery (FGATIR) MRI and high-field MRI pulse sequences that improve the ability to image the VIM region are emerging but have not yet been shown to have reliability and accuracy to serve as the primary method of VIM targeting. Currently, the most promising imaging approach to directly identify the VIM region for clinical purposes is MR diffusion tractography. In this review and update, the capabilities and limitations of conventional and emerging advanced methods for evaluation of internal thalamic anatomy are briefly reviewed. The basic principles of tractography most relevant to VIM targeting are provided for familiarization. Next, the key literature to date addressing applications of DTI and tractography for DBS and MRgFUS is summarized, emphasizing use of direct targeting. This literature includes 1-tract (dentatorubrothalamic tract [DRT]), 2-tract (pyramidal and somatosensory), and 3-tract (DRT, pyramidal, and somatosensory) approaches to VIM region localization through tractography. The authors introduce a 3-tract technique used at their institution, illustrating the oblique curved course of the DRT within the inferior thalamus as well as the orientation and relationship of the white matter tracts in the axial plane. The utility of this 3-tract tractography approach to facilitate VIM localization is illustrated with case examples of variable VIM location, targeting superior to the anterior commissure–posterior commissure plane, and treatment in the setting of pathologic derangement of thalamic anatomy. Finally, concepts demonstrated with these case examples and from the prior literature are synthesized to highlight several potential advantages of tractography for VIM region targeting.

Abstract Despite the widespread clinical use of dynamic susceptibility contrast (DSC) MRI, DSC-MRI methodology has not been standardized, hindering its utilization for response assessment in multicenter trials. Recently, the DSC-MRI Standardization Subcommittee of the Jumpstarting Brain Tumor Drug Development Coalition issued an updated consensus DSC-MRI protocol compatible with the standardized brain tumor imaging protocol (BTIP) for high-grade gliomas that is increasingly used in the clinical setting and is the default MRI protocol for the National Clinical Trials Network. After reviewing the basis for controversy over DSC-MRI protocols, this paper provides evidence-based best practices for clinical DSC-MRI as determined by the Committee, including pulse sequence (gradient echo vs spin echo), BTIP-compliant contrast agent dosing (preload and bolus), flip angle (FA), echo time (TE), and post-processing leakage correction. In summary, full-dose preload, full-dose bolus dosing using intermediate (60°) FA and field strength-dependent TE (40–50 ms at 1.5 T, 20–35 ms at 3 T) provides overall best accuracy and precision for cerebral blood volume estimates. When single-dose contrast agent usage is desired, no-preload, full-dose bolus dosing using low FA (30°) and field strength-dependent TE provides excellent performance, with reduced contrast agent usage and elimination of potential systematic errors introduced by variations in preload dose and incubation time.

OBJECTIVE Cushing’s disease arises from functioning adrenocorticotropic hormone (ACTH)–secreting pituitary adenomas. These tumors can be very small and evade detection by MRI. Empty sella syndrome is a phenomenon by which an arachnoid outpouching of CSF into the sella leads to compression of the pituitary, likely due to intracranial hypertension (a common issue in Cushing’s disease), further leading to difficulty in visualizing the pituitary gland that may contribute to difficulty in finding a tumor on MRI, so-called MRI-negative Cushing’s disease. The authors sought to examine the association between empty sella syndrome and MRI-negative Cushing’s disease. METHODS A single-institution database of Cushing’s disease cases from 2000 to 2017 was reviewed, and 197 cases were included in the analysis. One hundred eighty patients had a tissue diagnosis of Cushing’s disease and 17 had remission with surgery, but no definitive tissue diagnosis was obtained. Macroadenomas (tumors > 1 cm) were excluded. The degree of empty sella syndrome was graded on the degree of CSF visualized in the sella on midline sagittal T1-weighted MRI. RESULTS Of the 197 cases identified, 40 (20%) presented with MRI-negative disease, and empty sella syndrome was present in 49 cases (25%). MRI-negative disease was found in 18 (37%) of 49 empty sella cases versus 22 (15%) of 148 cases without empty sella syndrome present. Empty sella syndrome was significantly associated with MRI-negative disease (OR 3.32, 95% CI 1.61–6.74, p = 0.0018). Decreased thickness of the pituitary gland was also associated with MRI-negative disease (mean thickness 5.6 vs 6.8 mm, p = 0.0002). CONCLUSIONS Empty sella syndrome is associated with an increased rate of MRI-negative Cushing’s disease. Pituitary compression causing a relative reduction in the volume of the pituitary for imaging is a plausible cause for not detecting the tumor mass with MRI.

TPS2573 Background: Brain metastases, most commonly derived from melanoma, lung and breast cancers, are the most common brain tumor, with approximately 200,000 cases diagnosed annually in the United States. Median survival is on the order of months. For patients with clinically symptomatic brain metastases, approximately half succumb due to intracranial progression. In preclinical work, we demonstrated that brain metastases and primary tumors are often genetically distinct with frequent alterations in the CDK and PI3K pathway (Brastianos, Carter et al. Cancer Discovery 2015). Methods: We are currently accruing to a prospective multi-arm phase II study of CDK, PI3K/mTOR, and NTRK/ROS1 inhibitors in patients with brain metastases harboring alterations associated with sensitivity to these inhibitors (abemaciclib, paxalisib and entrectinib), respectively. Patients with new, recurrent or progressive brain metastases are eligible for this trial. Previously obtained tissue from brain metastases and extracranial sites (primary or extracranial metastases) are screened for the presence of these alterations, and if present in both tumor sites, patients will receive the appropriate corresponding targeted treatment. Screening is carried out with the SNaPshot NGS assay, which is a fully validated clinical test designed and developed at the MGH Center for Integrated Diagnostics. The primary endpoint of response rate (RR) in the central nervous system as per RANO criteria will be evaluated separately for each inhibitor, stratified by histology within each arm. There will be 21 evaluable patients assigned to each of the CDK and PI3K inhibitor and tumor type cohorts (breast, lung and other) and 10 patients assigned to the NTRK/ROS1 inhibitor cohort (lung) for a total of 136 evaluable patients. Although current systemic therapy for brain metastases is often ineffective, we hypothesize that targeted therapies will demonstrate efficacy in patients harboring the appropriate mutations. This study represents a novel individualized therapeutic approach in brain metastases, a disease with a critical need for effective therapy. Support: U10CA180821, U10CA180882, https://acknowledgments.alliancefound.org ; Genentech, Kazia Therapeutics Limited, Eli Lilly; Clinical trial information: NCT03994796 .

2502 Background: Patients with progressive or recurrent meningiomas have limited treatment options. Clinical trials of systemic therapies for meningiomas have failed to demonstrate benefit. FAK inhibition has a synthetic lethal relationship with NF2 loss. Given the predominance of NF2 mutations in meningiomas, we evaluated the efficacy of GSK2256098, a FAK inhibitor, as part of the first genomically-driven phase II study in recurrent or progressive grade I-III meningiomas. Methods: Eligible patients (pts) whose tumors screened positively for NF2 mutations were treated with GSK2256098 750mg po bid until progressive disease in 2 separate cohorts: grade I or II/III meningiomas. Two co-primary endpoints were used: progression-free survival at 6 months (PFS6) and response rate (RR) by Macdonald criteria; per study design, the trial would be declared positive if either endpoint was met. RR was evaluated across the overall cohort; PFS6 was evaluated within each subgroup. Historical benchmark data was obtained from Kaley et al. Neuro Oncol 2014. In the grade I group, 12 evaluable pts provided >79% power to detect a PFS6 rate >65% (vs. null hypothesis of 25%; alpha=0.014). In the grade II/III group, 24 evaluable pts provided >85% power to detect a PFS6 >41.5% (vs. null 15%; alpha=0.02). The threshold for promising results for PFS6 was: 7+/12(grade I) and 8+/24(grade II/III) pts. For RR, 36 evaluable pts provided >94% power to detect RR >20% (vs. null 2.5%; alpha= 0.012). Results: Of 322 pts screened for all mutation cohorts of the study, 36 eligible and evaluable pts with NF2 mutations were enrolled. Across all grades, one pt had a partial response and 24 had stable disease as best response to treatment. In Grade I pts, the observed PFS6 rate was 83% (10/12 pts; 95% CI: 52-98%). In Grade II/III pts, the observed PFS6 rate was 33% (8/24 pts; 95% CI: 16-55%). The study met PFS6 efficacy endpoint both for the Grade I and the Grade II/III cohorts. Treatment was well tolerated. Only 7 patients had a maximum grade-3 adverse event that was at least possibly related to treatment; toxicities across these pts included: proteinuria (2), rash (1), pain (1), ALT (1), AST (1), cholecystitis (1), hypertriglyceridemia (1), apraxia (1), and lymphopenia (1) with no grade 4 or 5 events. Conclusions: GSK2256098 had excellent tolerability andresulted in an improved PFS6 rate in pts with recurrent or progressive NF2-mutated meningiomas. Trial endpoint was met. FAK inhibition warrants further evaluation in this patient population. Support: U10CA180821, U10CA180882; https://acknowledgments.alliancefound.org Clinical trial information: NCT02523014 .

Abstract Magnetic resonance guided high intensity focused ultrasound is a novel, non-invasive, image-guided procedure that is able to ablate intracranial tissue with submillimetre precision. It is currently FDA approved for essential tremor and tremor dominant Parkinson’s disease. The aim of this update is to review the limitations of current landmark-based targeting techniques of the ventral intermediate nucleus and demonstrate the role of emerging imaging techniques that are relevant for both magnetic resonance guided high intensity focused ultrasound and deep brain stimulation. A significant limitation of standard MRI sequences is that the ventral intermediate nucleus, dentatorubrothalamic tract, and other deep brain nuclei cannot be clearly identified. This paper provides original, annotated images demarcating the ventral intermediate nucleus, dentatorubrothalamic tract, and other deep brain nuclei on advanced MRI sequences such as fast grey matter acquisition T1 inversion recovery, quantitative susceptibility mapping, susceptibility weighted imaging, and diffusion tensor imaging tractography. Additionally, the paper reviews clinical efficacy of targeting with these novel MRI techniques when compared to current established landmark-based targeting techniques. The paper has widespread applicability to both deep brain stimulation and magnetic resonance guided high intensity focused ultrasound.

AbstractA recent meeting was held on March 22, 2019, among the FDA, clinical scientists, pharmaceutical and biotech companies, clinical trials cooperative groups, and patient advocacy groups to discuss challenges and potential solutions for increasing development of therapeutics for central nervous system metastases. A key issue identified at this meeting was the need for consistent tumor measurement for reliable tumor response assessment, including the first step of standardized image acquisition with an MRI protocol that could be implemented in multicenter studies aimed at testing new therapeutics. This document builds upon previous consensus recommendations for a standardized brain tumor imaging protocol (BTIP) in high-grade gliomas and defines a protocol for brain metastases (BTIP-BM) that addresses unique challenges associated with assessment of CNS metastases. The “minimum standard” recommended pulse sequences include: (i) parameter matched pre- and post-contrast inversion recovery (IR)–prepared, isotropic 3D T1-weighted gradient echo (IR-GRE); (ii) axial 2D T2-weighted turbo spin echo acquired after injection of gadolinium-based contrast agent and before post-contrast 3D T1-weighted images; (iii) axial 2D or 3D T2-weighted fluid attenuated inversion recovery; (iv) axial 2D, 3-directional diffusion-weighted images; and (v) post-contrast 2D T1-weighted spin echo images for increased lesion conspicuity. Recommended sequence parameters are provided for both 1.5T and 3T MR systems. An “ideal” protocol is also provided, which replaces IR-GRE with 3D TSE T1-weighted imaging pre- and post-gadolinium, and is best performed at 3T, for which dynamic susceptibility contrast perfusion is included. Recommended perfusion parameters are given.

Recognition of key concepts of structural and functional anatomy of the cerebellum can facilitate image interpretation and clinical correlation. Recently, the human brain mapping literature has increased our understanding of cerebellar anatomy, function, connectivity with the cerebrum, and significance of lesions involving specific areas. Both the common names and numerically based Schmahmann classifications of cerebellar lobules are illustrated. Anatomic patterns, or signs, of key fissures and white matter branching are introduced to facilitate easy recognition of the major anatomic features. Color-coded overlays of cross-sectional imaging are provided for reference of more complex detail. Examples of exquisite detail of structural and functional cerebellar anatomy at 7 T MRI are also depicted. The functions of the cerebellum are manifold with the majority of areas involved with non-motor association function. Key concepts of lesion–symptom mapping which correlates lesion location to clinical manifestation are introduced, emphasizing that lesions in most areas of the cerebellum are associated with predominantly non-motor deficits. Clinical correlation is reinforced with examples of intrinsic pathologic derangement of cerebellar anatomy and altered functional connectivity due to pathology of the cerebral hemisphere. The purpose of this pictorial review is to illustrate basic concepts of these topics in a cross-sectional imaging-based format that can be easily understood and applied by radiologists.