The Massachusetts General Hospital Acute Stroke Imaging Algorithm: An Experience and Evidence Based Approach

The Massachusetts General Hospital Neuroradiology Division employed an experience and evidence based approach to develop a neuroimaging algorithm to best select patients with severe ischemic strokes caused by anterior circulation occlusions (ACOs) for intravenous tissue plasminogen activator and endovascular treatment. Methods found to be of value included the National Institutes of Health Stroke Scale (NIHSS), non-contrast CT, CT angiography (CTA) and diffusion MRI. Perfusion imaging by CT and MRI were found to be unnecessary for safe and effective triage of patients with severe ACOs. An algorithm was adopted that includes: non-contrast CT to identify hemorrhage and large hypodensity followed by CTA to identify the ACO; diffusion MRI to estimate the core infarct; and NIHSS in conjunction with diffusion data to estimate the clinical penumbra

Optimal Brain MRI Protocol for New Neurological Complaint

Background/Purpose Patients with neurologic complaints are imaged with MRI protocols that may include many pulse sequences. It has not been documented which sequences are essential. We assessed the diagnostic accuracy of a limited number of sequences in patients with new neurologic complaints. Methods: 996 consecutive brain MRI studies from patients with new neurological complaints were divided into 2 groups. In group 1, reviewers used a 3-sequence set that included sagittal T1-weighted, axial T2-weighted fluid-attenuated inversion recovery, and axial diffusion-weighted images. Subsequently, another group of studies were reviewed using axial susceptibility-weighted images in addition to the 3 sequences. The reference standard was the study's official report. Discrepancies between the limited sequence review and the reference standard including Level I findings (that may require immediate change in patient management) were identified. Results: There were 84 major findings in 497 studies in group 1 with 21 not identified in the limited sequence evaluations: 12 enhancing lesions and 3 vascular abnormalities identified on MR angiography. The 3-sequence set did not reveal microhemorrhagic foci in 15 of 19 studies. There were 117 major findings in 499 studies in group 2 with 19 not identified on the 4-sequence set: 17 enhancing lesions and 2 vascular lesions identified on angiography. All 87 Level I findings were identified using limited sequence (56 acute infarcts, 16 hemorrhages, and 15 mass lesions). Conclusion: A 4-pulse sequence brain MRI study is sufficient to evaluate patients with a new neurological complaint except when contrast or angiography is indicated

Automatic assessment of glioma burden: A deep learning algorithm for fully automated volumetric and bi-dimensional measurement

Background Longitudinal measurement of glioma burden with MRI is the basis for treatment response assessment. In this study, we developed a deep learning algorithm that automatically segments abnormal fluid attenuated inversion recovery (FLAIR) hyperintensity and contrast-enhancing tumor, quantitating tumor volumes as well as the product of maximum bidimensional diameters according to the Response Assessment in Neuro-Oncology (RANO) criteria (AutoRANO). Methods Two cohorts of patients were used for this study. One consisted of 843 preoperative MRIs from 843 patients with low- or high-grade gliomas from 4 institutions and the second consisted of 713 longitudinal postoperative MRI visits from 54 patients with newly diagnosed glioblastomas (each with 2 pretreatment “baseline” MRIs) from 1 institution. Results The automatically generated FLAIR hyperintensity volume, contrast-enhancing tumor volume, and AutoRANO were highly repeatable for the double-baseline visits, with an intraclass correlation coefficient (ICC) of 0.986, 0.991, and 0.977, respectively, on the cohort of postoperative GBM patients. Furthermore, there was high agreement between manually and automatically measured tumor volumes, with ICC values of 0.915, 0.924, and 0.965 for preoperative FLAIR hyperintensity, postoperative FLAIR hyperintensity, and postoperative contrast-enhancing tumor volumes, respectively. Lastly, the ICCs for comparing manually and automatically derived longitudinal changes in tumor burden were 0.917, 0.966, and 0.850 for FLAIR hyperintensity volume, contrast-enhancing tumor volume, and RANO measures, respectively. Conclusions Our automated algorithm demonstrates potential utility for evaluating tumor burden in complex posttreatment settings, although further validation in multicenter clinical trials will be needed prior to widespread implementation

Bones of the Past (Video)

A 44-year-old woman presented with two episodes of binocular horizontal diplopia within one year. She had a history of Cushing's syndrome status post transsphenoidal resection and bilateral adrenalectomy 4 years prior, hypertension, and secondary diabetes mellitus. Nine months prior she developed severe right-sided headache and a right abducens nerve palsy, which improved over several weeks. At presentation, she described left-sided headache and neck pain, followed by development of horizontal diplopia worst on left gaze. She had normal visual acuity, color vision, visual fields, pupillary function, and fundi. There was an isolated left abduction deficit with incomitant esotropia. MRI of the brain with contrast showed stable residual postoperative findings in the sella, with unchanged residual contrast-enhancing pituitary tissue, and some contact of the left AICA with the left abducens nerve but no enhancement or other abnormality of the abducens nerves or extraocular muscles. A second radiologic opinion noted previously missed confluent but heterogeneous T1-hypointense marrow in the clivus with diffusion restriction, which in retrospect was progressively worsening over serial scans from preceding years. Lumbar puncture yielded normal cerebrospinal fluid. A CT PET of the skull base showed abnormal enhancing soft tissue within the sella and extending along the epidural surface of the clivus, and progression of bony sclerosis within the clivus compared to prior scans; there was hypermetabolism of the clivus. Follow-up MRI demonstrated progression of the changes in the sella and clivus compared to her postoperative imaging. Serum adrenocorticotropic; hormone (ACTH) levels were significantly higher than prior. A transsphenoidal biopsy revealed tumor with surrounding fibrotic reaction in the sella, sphenoid sinus and superior clivus. Pathology was consistent with corticotroph adenoma with elevated; proliferation index and scattered mitoses. A diagnosis of Nelson's syndrome was made. The patient underwent radiation therapy, with full resolution of her diplopia and headache

Ictal fMRI: Mapping Seizure Topography with Rhythmic BOLD Oscillations

Functional magnetic resonance imaging (fMRI) has shown elevations in the blood-oxygen-level-dependent (BOLD) signal associated with, but insensitive for, seizure. Rather than evaluating absolute BOLD signal elevations, assessing rhythmic oscillations in the BOLD signal with fMRI may improve the accuracy of seizure mapping. We report a case of a patient with non-convulsive, right hemispheric seizures who underwent fMRI. Unbiased processing methods revealed a map of rhythmically oscillating BOLD signal over the cortical region affected by seizure, and synchronous BOLD signal in the contralateral cerebellum. High-resolution fMRI may help identify the spatial topography of seizure and provide insights into seizure physiology