Review of Artificial Intelligence Training Tools and Courses for Radiologists.

Artificial intelligence (AI) systems play an increasingly important role in all parts of the imaging chain, from image creation to image interpretation to report generation. In order to responsibly manage radiology AI systems and make informed purchase decisions about them, radiologists must understand the underlying principles of AI. Our task force was formed by the Radiology Research Alliance (RRA) of the Association of University Radiologists to identify and summarize a curated list of current educational materials available for radiologists.

T1ρ imaging in premanifest Huntington disease reveals changes associated with disease progression.

BACKGROUND: Imaging biomarkers sensitive to Huntington's disease (HD) during the premanifest phase preceding motor diagnosis may accelerate identification and evaluation of potential therapies. For this purpose, quantitative MRI sensitive to tissue microstructure and metabolism may hold great potential. We investigated the potential value of T1ρ relaxation to detect pathological changes in premanifest HD (preHD) relative to other quantitative relaxation parameters. METHODS: Quantitative MR parametric mapping was used to assess differences between 50 preHD subjects and 26 age- and sex-matched controls. Subjects with preHD were classified into two progression groups based on their CAG-age product (CAP) score; a high and a low/moderate CAP group. Voxel-wise and region-of-interest analyses were used to assess changes in the quantitative relaxation times. RESULTS: T1ρ showed a significant increase in the relaxation times in the high-CAP group, as compared to controls, largely in the striatum. The T1ρ changes in the preHD subjects showed a significant relationship with CAP score. No significant changes in T2 or T2* relaxation times were found in the striatum. T2* relaxation changes were found in the globus pallidus, but no significant changes with disease progression were found. CONCLUSION: These data suggest that quantitative T1ρ mapping may provide a useful marker for assessing disease progression in HD. The absence of T2 changes suggests that the T1ρ abnormalities are unlikely owing to altered water content or tissue structure. The established sensitivity of T1ρ to pH and glucose suggests that these factors are altered in HD perhaps owing to abnormal mitochondrial function.

Hypertensive posterior reversible encephalopathy syndrome causing posterior fossa edema and hydrocephalus.

Posterior reversible encephalopathy syndrome (PRES) is a well characterized entity resulting from the inability of cerebral autoregulation to adequately protect the brain from uncontrolled hypertension. It primarily affects the occipital lobes, but can also involve the structures in the posterior fossa including the brainstem and cerebellum. Treatment usually consists of strict blood pressure control, but more aggressive management may be indicated with acutely worsening neurological status. We present a patient with hypertensive encephalopathy that resulted in hydrocephalus and brainstem compression necessitating surgical decompression requiring ventriculostomy and suboccipital craniectomy. In rare cases, PRES can present with severe brainstem compression requiring emergent posterior fossa decompression. When brainstem signs are present on exam, emergent posterior fossa decompression may be safer than ventriculostomy alone.

Multi-site study of surgical practice in neurosurgery based on surgical process models.

Surgical Process Modelling (SPM) was introduced to improve understanding the different parameters that influence the performance of a Surgical Process (SP). Data acquired from SPM methodology is enormous and complex. Several analysis methods based on comparison or classification of Surgical Process Models (SPMs) have previously been proposed. Such methods compare a set of SPMs to highlight specific parameters explaining differences between populations of patients, surgeons or systems. In this study, procedures performed at three different international University hospitals were compared using SPM methodology based on a similarity metric focusing on the sequence of activities occurring during surgery. The proposed approach is based on Dynamic Time Warping (DTW) algorithm combined with a clustering algorithm. SPMs of 41 Anterior Cervical Discectomy (ACD) surgeries were acquired at three Neurosurgical departments; in France, Germany, and Canada. The proposed approach distinguished the different surgical behaviors according to the location where surgery was performed as well as between the categorized surgical experience of individual surgeons. We also propose the use of Multidimensional Scaling to induce a new space of representation of the sequences of activities. The approach was compared to a time-based approach (e.g. duration of surgeries) and has been shown to be more precise. We also discuss the integration of other criteria in order to better understand what influences the way the surgeries are performed. This first multi-site study represents an important step towards the creation of robust analysis tools for processing SPMs. It opens new perspectives for the assessment of surgical approaches, tools or systems as well as objective assessment and comparison of surgeon's expertise.

Intracranial glioblastoma with drop metastases to the spine after stereotactic biopsy.

BACKGROUND: Glioblastoma (GBM) is the most common primary intracranial tumor, but metastases are rarely reported. Previous reports have documented the occurrence of drop metastases to the spine. However, few of these reports have demonstrated the occurrence of spinal metastases after biopsy with stable intracranial disease. Here we present such a case. CASE DESCRIPTION: We present a case of GBM metastatic to the spinal cord after a stereotactic biopsy with stable intracranial disease. To our knowledge, this occurrence has only been reported in one previous case. CONCLUSION: We propose that traversing the lateral ventricle at the time of biopsy contributed to cerebrospinal fluid seeding with tumor cells and subsequent development of spinal disease.

Traumatic intracranial hemorrhage in patients taking dabigatran: report of 3 cases and review of the literature.

BACKGROUND AND IMPORTANCE: Dabigatran is a direct thrombin inhibitor gaining popularity as a stroke prevention agent in patients with atrial fibrillation. In comparison with warfarin, dabigatran showed superiority in stroke prevention, but lower rates of major hemorrhage and intracerebral hemorrhage. Although warfarin has a well-established reversal strategy, there is far less experience reversing dabigatran. CLINICAL PRESENTATION: We present our experience with 3 patients who experienced an intracranial hemorrhage either spontaneously or after low-energy cranial trauma and review the available literature describing dabigatran use in patients with traumatic brain injury. CONCLUSION: Intracranial hemorrhage in patients taking anticoagulants and/or antiplatelets can have either a benign or malignant clinical course. At this time, there is little experience with dabigatran reversal; however, several strategies for rapid reversal have been proposed. All patients with intracranial hemorrhage taking dabigatran should be admitted for close neurological monitoring and serial imaging.

Incidence of cerebral ischemic events after discontinuation of clopidogrel in patients with intracranial aneurysms treated with stent-assisted techniques.

OBJECT: The optimal antiplatelet medication protocol for prevention of thrombotic complications after stent-assisted coil embolization of cerebral aneurysms is unclear. Early cessation of antiplatelet agents may be associated with an increased risk of cerebral ischemic events. In this study, the authors assess the incidence of stroke or transient ischemic attack (TIA) following discontinuation of a 6-week course of clopidogrel in patients with cerebral aneurysms treated with stent-assisted techniques. METHODS: A retrospective review was conducted in all patients with cerebral aneurysms undergoing stent-assisted coil embolization or stent-in-stent flow diversion at the University of Iowa during a 24-month period. The antiplatelet protocol was 81 mg aspirin and 75 mg clopidogrel daily for 6 weeks, followed by 325 mg aspirin daily indefinitely. The incidence of stroke or TIA was determined by a retrospective review of medical records generated during a 3-month period following discontinuation of clopidogrel. RESULTS: A total of 154 patients underwent aneurysm treatment with stent techniques during this interval. Documentation of neurological follow-up 3 months after discontinuation of a 6-week clopidogrel treatment was available in 121 (78.6%) of 154 patients. Of these 121 patients, 114 were treated with stent-assisted coil embolization and 7 with stent-in-stent flow diversion. Six patients (5%) suffered an ischemic event after cessation of clopidogrel, with 2 events occurring within the first 2 weeks. Specifically, the rate of ischemic events was 5 (4.3%) of 114 in the "stent-coil" treatment group and 1 (14.3%) of 7 in the stent-in-stent group. Treatment had been performed in the setting of a subarachnoid hemorrhage in 1 patient. Atypical aneurysm features and technical factors predisposing to thrombotic events were found in all but one of these patients. Similarly, cardiovascular risk factors were present in 5 of the 6 patients in whom ischemic events developed after clopidogrel discontinuation. CONCLUSIONS: Clopidogrel discontinuation is associated with a 5% risk of ischemic events in patients treated with stent techniques. Any stroke related to clopidogrel discontinuation is avoidable, and longer treatment is therefore clearly necessary. Patients with cardiovascular risk factors, high-risk aneurysm features, and those undergoing stent-in-stent flow diversion might benefit the most from longer clopidogrel therapy.

Skull base inverted papilloma: a comprehensive review.

Skull base inverted papilloma (IP) is an unusual entity for many neurosurgeons. IP is renowned for its high rate of recurrence, its ability to cause local destruction, and its association with malignancy. This paper is a comprehensive review of the reports, studies, and reviews published in the current biomedical literature from 1947 to September 2010 and synthesize this information to focus on its potential invasion to the base of the skull and possible intradural extension. The objective is to familiarize the clinician with the different aspects of this unusual disease. The role of modern diagnostic tools in medical imaging in order to assess clearly the limits of the tumors and to enhance the efficiency and the safety in the choice of a surgical approach is pointed out. The treatment guidelines for IP have undergone a complex evolution that continues today. Radical excision of the tumour is technically difficult and often incomplete. Successful management of IP requires resection of the affected mucosa which could be achieved with open surgery, endoscopic, or combined approach. Radio and chemotherapy were used for certain indications. More optimally research would be a multicenter randomized trials with large size cohorts.

Sinonasal teratocarcinosarcoma with intracranial extension: case report and literature review.

Sinonasal teratocarcinosarcoma (SNTCS) is an extremely rare malignancy of the paranasal sinuses that possesses the histopathologic features of both teratomas and carcinosarcomas. We report the case of a 58-year-old white man who presented with a 1-year history of a gradually enlarging left-sided nasal mass. The patient had previously undergone endoscopic sinus surgery at another facility, and the final pathologic specimen was reported as an SNTCS with positive margins. He was then referred to our institution, where he underwent a craniofacial resection combined with endoscopic intranasal resection. Postoperatively, he received combined chemotherapy and irradiation. At 48 months of follow-up, he was alive without evidence of disease.

BEaST: brain extraction based on nonlocal segmentation technique.

Brain extraction is an important step in the analysis of brain images. The variability in brain morphology and the difference in intensity characteristics due to imaging sequences make the development of a general purpose brain extraction algorithm challenging. To address this issue, we propose a new robust method (BEaST) dedicated to produce consistent and accurate brain extraction. This method is based on nonlocal segmentation embedded in a multi-resolution framework. A library of 80 priors is semi-automatically constructed from the NIH-sponsored MRI study of normal brain development, the International Consortium for Brain Mapping, and the Alzheimer's Disease Neuroimaging Initiative databases. In testing, a mean Dice similarity coefficient of 0.9834±0.0053 was obtained when performing leave-one-out cross validation selecting only 20 priors from the library. Validation using the online Segmentation Validation Engine resulted in a top ranking position with a mean Dice coefficient of 0.9781±0.0047. Robustness of BEaST is demonstrated on all baseline ADNI data, resulting in a very low failure rate. The segmentation accuracy of the method is better than two widely used publicly available methods and recent state-of-the-art hybrid approaches. BEaST provides results comparable to a recent label fusion approach, while being 40 times faster and requiring a much smaller library of priors.

Minimally invasive video-assisted thyroidectomy and parathyroidectomy with intraoperative recurrent laryngeal nerve monitoring.

Objective. Our goal is to study the feasibility of using intraoperative neuromonitoring (IONM) in minimally invasive video-assisted thyroidectomy and parathyroidectomy (MIVAT/P) with emphasis given to the identification of recurrent laryngeal nerve (RLN). Methods. Consecutive series of forty-seven patients with seventy-seven recurrent laryngeal nerves at risk undergoing both MIVAT/P and IONM were enrolled in this retrospective, nonrandomized analysis study. All operations were performed by the same surgeon within an academic institution setting. All patients underwent vocal cord evaluation postoperatively. Demographics and intraoperative and postoperative complications following surgery were collected. Results. Out of seventy-seven RLNs, there was one permanent unilateral RLN injury (1.29%) in a patient with advanced papillary thyroid cancer, managed by cord injection. There was another transient RLN paresis that resolved spontaneously (1.29%). There were no instances of equipment malfunction or interference. Conclusions. To our knowledge, this is the first reported MIVAT/P series from the United States of America with a standardized IONM technique. The technical feasibility of IONM seems acceptable and may serve as a meaningful adjunct to the visual identification of nerves. Neuromonitoring during MIVAT/P is effective in providing identification of laryngeal nerves and enables surgeons to feel more comfortable with MIVAT/P. Comparative series are needed for further evaluation.