Simple quantitative planimetric measurement of nigrosome-1 for clinical settings.

INTRODUCTION: Loss of MRI hyperintense signal in nigrosome-1 (assessed with susceptibility-weighted imaging) is a biomarker for Parkinson's disease (PD). Current clinical practice involves subjectively rating the appearance of nigrosome-1 which is challenging. The study aimed to test and compare a simple method for quantifying nigrosome-1 with the current subjective rating method. METHODS: Two experienced neuroradiologists measured area of hyperintense signal in nigrosome-1 (quantitative method) and rated nigrosome-1 appearance (as normal, attenuated, or absent; subjective method) in 42 patients encompassing the full spectrum of nigrosome-1 integrity (21 patients aged 55.5 ± 20.9 years with Essential tremor (ET) and a subset of 21 patients aged 69.6 ± 8.6 years with PD). Neuroradiologists were blinded to each other's measurements, clinical notes, and patient group. RESULTS: Both methods yielded a significant difference between the groups (PD vs ET; p < 0.001). Pooled (across sides) area of nigrosome-1 hyperintense signal was significantly smaller in the PD group (median = 2.1 mm2, range = 0-15.8 mm2) than ET group (median = 8.3 mm2, range = 0-15.7 mm2; p < 0.001). Inter-rater reliability was high to very high for both methods (subjective: weighted kappa = 0.640, p < 0.001; quantitative: W = 0.733, p = 0.004). Our primary hypothesis that area of nigrosome-1 hyperintense signal exhibits higher inter-rater reliability than subjective rating of nigrosome-1 appearance was not supported. CONCLUSION: The simple quantitative method, used with subjectively rated nigrosome-1 appearance, may improve confidence in longitudinal clinical reporting, when nigrosome-1 is attenuated. However, further work on the incremental diagnostic value of planimetry and bias, repeatability and reproducibility are needed before it can be recommended in clinical practice.

Imaging evaluation of a proposed 3D generative model for MRI to CT translation in the lumbar spine.

BACKGROUND CONTEXT: A computed tomography (CT) and magnetic resonance imaging (MRI) are used routinely in the radiologic evaluation and surgical planning of patients with lumbar spine pathology, with the modalities being complimentary. We have developed a deep learning algorithm which can produce 3D lumbar spine CT images from MRI data alone. This has the potential to reduce radiation to the patient as well as burden on the health care system. PURPOSE: The purpose of this study is to evaluate the accuracy of the synthetic lumbar spine CT images produced using our deep learning model. STUDY DESIGN: A training set of 400 unpaired CTs and 400 unpaired MRI scans of the lumbar spine was used to train a supervised 3D cycle-Gan model. Evaluators performed a set of clinically relevant measurements on 20 matched synthetic CTs and true CTs. These measurements were then compared to assess the accuracy of the synthetic CTs. PATIENT SAMPLE: The evaluation data set consisted of 20 patients who had CT and MRI scans performed within a 30-day period of each other. All patient data was deidentified. Notable exclusions included artefact from patient motion, metallic implants or any intervention performed in the 30 day intervening period. OUTCOME MEASURES: The outcome measured was the mean difference in measurements performed by the group of evaluators between real CT and synthetic CTs in terms of absolute and relative error. METHODS: Data from the 20 MRI scans was supplied to our deep learning model which produced 20 "synthetic CT" scans. This formed the evaluation data set. Four clinical evaluators consisting of neurosurgeons and radiologists performed a set of 24 clinically relevant measurements on matched synthetic CT and true CTs in 20 patients. A test set of measurements were performed prior to commencing data collection to identify any significant interobserver variation in measurement technique. RESULTS: The measurements performed in the sagittal plane were all within 10% relative error with the majority within 5% relative error. The pedicle measurements performed in the axial plane were considerably less accurate with a relative error of up to 34%. CONCLUSIONS: The computer generated synthetic CTs demonstrated a high level of accuracy for the measurements performed in-plane to the original MRIs used for synthesis. The measurements performed on the axial reconstructed images were less accurate, attributable to the images being synthesized from nonvolumetric routine sagittal T1-weighted MRI sequences. It is hypothesized that if axial sequences or volumetric data were input into the algorithm these measurements would have improved accuracy.

Pure retroclival subdural hemorrhage secondary to ruptured posterior communicating artery aneurysm.

Approximately 3% of intracranial aneurysm ruptures result in an associated subdural hematoma (SDH). SDH from intracranial aneurysm rupture without radiographic evidence of SAH, however, is rare. We report a case of an isolated retroclival SDH secondary to an intracranial aneurysm rupture.

Cavitating Lung Disease Associated With Sudden Death.

CASE PRESENTATION: A 16-year-old boy presented with 6 days of left iliac fossa pain. He had a medical history of right subtalar dislocation and appendicitis requiring laparotomy 3 years earlier, complicated by wound dehiscence. His family history was significant for his brother's sudden death 3 weeks prior after a 12-month illness with intermittent epigastric pain, weight loss, and hemoptysis. Travel history was significant for travel to the Philippines 3 years prior, in which he spent time in the hospital for appendicitis.

Computed tomography scan measurements of the globe and orbit to assess the risks of traumatic complications from medial peribulbar anaesthesia.

Complications of peribulbar anaesthesia include retrobulbar haemorrhage, globe perforation and brainstem anaesthesia. Therefore, this study took measurements relating the proximity of medial canthus to the optic nerve and also the safe angle between orbit and globe using 200 multiplanar reconstructed computed tomography (CT) images of the orbit. The principal results show that in 1.5% of the sample, the optic nerve is within 20 mm of the medial canthus, with a minimum distance of 15 mm. One% have a safe angle of 10 degrees or less between bone and globe. None of the demographic data, nor axial length were predictive of these results. We have shown that there are a minority of patients with unusual orbital anatomy. This places them at a theoretical higher risk of complications. These cases are not currently predicted by measured data.

Syringomyelia intermittens: highlighting the complex pathophysiology of syringomyelia. Illustrative case.

BACKGROUND: Chiari Type I malformation (CM1) is a disorder recognized by caudal displacement of the cerebellar tonsils through the foramen magnum and into the cervical canal. Syringomyelia is frequently found in patients with CM1, but the pathophysiology of syringomyelia remains an enigma. As a general consensus, symptomatic patients should be treated and asymptomatic patients without a syrinx should not be treated. Mildly symptomatic patients or asymptomatic patients with a syrinx, on the other hand, pose a more challenging dilemma, as the natural evolution is uncertain. For many surgeons, the presence of a syrinx is an indication to offer surgery even if the patient is asymptomatic or mildly symptomatic. OBSERVATIONS: The authors describe an illustrative case of a 31-year-old female with an incidental finding of a CM1 malformation and cervical syrinx in 2013. Conservative management was advocated as the patient was asymptomatic. Monitoring of the syrinx over a course of 8 years showed resolution, followed by reappearance and finally a complete resolution in 2021. A review of the literature and the possible pathophysiology is discussed. LESSONS: The unusual course of this patient highlights the importance of guiding treatment by clinical symptoms, not radiological findings. Furthermore it reflects the complexity of the pathophysiology and the uncertain natural history of syringomyelia.

Diagnostic accuracy of the appearance of Nigrosome-1 on magnetic resonance imaging in Parkinson's disease: A systematic review and meta-analysis.

INTRODUCTION: There is currently no definitive diagnostic test for Parkinson's disease (PD) and the current diagnostic procedure primarily relies on clinical manifestations. A hypointense appearance of nigrosome-1 (or absence of the "swallow tail" sign) on magnetic resonance imaging (MRI) has been proposed as a biomarker for PD. This meta-analysis examined the diagnostic accuracy of the appearance of nigrosome-1 on Magnetic Resonance Imaging (MRI) in differentiating idiopathic PD patients from healthy adults. METHODS: Databases (MEDLINE, Embase, Scopus) were searched from 2012 (first publication of nigrosome-1 MRI scans) up until September 2019. Two researchers independently screened all titles and abstracts to identify studies that met the inclusion criteria and extracted relevant articles in a uniform manner. Two authors independently extracted data and assessed the risk of bias using a customized QUADAS-2 tool. Pooled sensitivity and specificity were calculated using a hierarchical summary receiver operating characteristic approach, as were positive and negative likelihood ratios. RESULTS: Nineteen studies containing a total of 1508 participants (903 idiopathic PD patients and 605 healthy controls) were included. The overall sensitivity and specificity were 0.94 (95%CI, 0.93-0.96) and 0.90 (95%CI, 0.88-0.92), respectively. The likelihood ratios for positive and negative test results were 9.72 (95%CI, 5.58-16.04) and 0.08 (95%CI, 0.05-0.12). The pooled area under the receiver operating characteristics curve (AUC) in the diagnosis of idiopathic PD was 0.98. CONCLUSIONS: Visual assessment of the nigrosome-1 appearance, at 3 or 7T, yields excellent diagnostic accuracy for differentiating idiopathic PD from healthy adults.

Convolutional neural networks for brain tumour segmentation.

The introduction of quantitative image analysis has given rise to fields such as radiomics which have been used to predict clinical sequelae. One growing area of interest for analysis is brain tumours, in particular glioblastoma multiforme (GBM). Tumour segmentation is an important step in the pipeline in the analysis of this pathology. Manual segmentation is often inconsistent as it varies between observers. Automated segmentation has been proposed to combat this issue. Methodologies such as convolutional neural networks (CNNs) which are machine learning pipelines modelled on the biological process of neurons (called nodes) and synapses (connections) have been of interest in the literature. We investigate the role of CNNs to segment brain tumours by firstly taking an educational look at CNNs and perform a literature search to determine an example pipeline for segmentation. We then investigate the future use of CNNs by exploring a novel field-radiomics. This examines quantitative features of brain tumours such as shape, texture, and signal intensity to predict clinical outcomes such as survival and response to therapy.

Discrepancy rates in reporting of acute stroke CT.

INTRODUCTION: With increasing after-hours workloads there has been reliance on registrars to report after-hours acute stroke CT scans at our institution. This practice was reviewed for the perceived possibility of error and poor patient outcomes by the reliance on after-hours registrar reports. Through an audit of 3 years of these studies, we proposed to investigate if our current practice is safe and whether it results in poor patient outcomes. METHODS: Following ethics approval, all after-hours acute stroke CT scan reports from September 2012 to August 2015 were identified using the PACS. All reports were reviewed with data recorded on a written worksheet then transferred to an Excel spreadsheet for analysis. The consultant report was used as the gold standard. In cases where discrepancies occurred, medical records were reviewed. RESULTS: Eight hundred and ninety-four acute stroke CT scans were identified in the audit period with a subset of 316 studies identified where a registrar report was issued at time of scan and checked the following day by a radiology consultant. There were 114 discrepancies (10 were major, 51 were minor, and 53 other). In three discrepancy cases, the patient's clinical course was altered. There were no adverse outcomes as a result of a discrepancy. Using a radiology consultant as the gold standard the major discrepancy rate was ≈3% in the after-hours setting. CONCLUSION: Our 3 year retrospective audit demonstrates that our practice of registrar report issued at the time of CT scan checked the following day by a radiologist has a low major discrepancy rate and that patient safety was not compromised. These results support the continuation of our current practice.

Whispering dysphonia (DYT4 dystonia) is caused by a mutation in the TUBB4 gene.

OBJECTIVE: A study was undertaken to identify the gene underlying DYT4 dystonia, a dominantly inherited form of spasmodic dysphonia combined with other focal or generalized dystonia and a characteristic facies and body habitus, in an Australian family. METHODS: Genome-wide linkage analysis was carried out in 14 family members followed by genome sequencing in 2 individuals. The index patient underwent a detailed neurological follow-up examination, including electrophysiological studies and magnetic resonance imaging scanning. Biopsies of the skin and olfactory mucosa were obtained, and expression levels of TUBB4 mRNA were determined by quantitative real-time polymerase chain reaction in 3 different cell types. All exons of TUBB4 were screened for mutations in 394 unrelated dystonia patients. RESULTS: The disease-causing gene was mapped to a 23cM region on chromosome 19p13.3-p13.2 with a maximum multipoint LOD score of 5.338 at markers D9S427 and D9S1034. Genome sequencing revealed a missense variant in the TUBB4 (tubulin beta-4; Arg2Gly) gene as the likely cause of disease. Sequencing of TUBB4 in 394 unrelated dystonia patients revealed another missense variant (Ala271Thr) in a familial case of segmental dystonia with spasmodic dysphonia. mRNA expression studies demonstrated significantly reduced levels of mutant TUBB4 mRNA in different cell types from a heterozygous Arg2Gly mutation carrier compared to controls. INTERPRETATION: A mutation in TUBB4 causes DYT4 dystonia in this Australian family with so-called whispering dysphonia, and other mutations in TUBB4 may contribute to spasmodic dysphonia. Given that TUBB4 is a neuronally expressed tubulin, our results imply abnormal microtubule function as a novel mechanism in the pathophysiology of dystonia.

Retinal vascular abnormalities in patients with cerebral amyloid angiopathy.

OBJECTIVE: To describe the ophthalmology findings in patients with cerebral amyloid angiopathy (CAA). METHODS: Data source and subjects: 7 consecutive patients admitted to a tertiary stroke unit with CAA-related hemorrhage, confirmed on magnetic resonance brain imaging gradient echo sequences by 2 independent neuroradiologists. DESIGN: case series. Measurements and data analysis: fundus colored photographs and fundus fluorescein angiography. RESULTS: All patients showed bilateral multiple dot and blot hemorrhages as well as multiple microaneurysms on fundus fluorescein angiography. CONCLUSION: Microaneurysms and dot and blot hemorrhages funduscopically mirror the histopathology of CAA. This case series is the first to describe retinal vessel changes in CAA and, if confirmed in larger population studies, has the potential to provide insights into the natural history of CAA.

Treatment of metastatic sialoblastoma with chemotherapy and surgery.

Tumors of the salivary gland are very uncommon in children. Sialoblastoma is a rare, aggressive, blastomatous, and potentially malignant congenital tumor. Distant metastases are rare. We present a case of sialoblastoma with lung metastases that developed in a 4-year-old girl adjacent to a congenital nevus in the left cheek. The tumor was inoperable at diagnosis but the largest of the pulmonary metastases was removed surgically. The patient responded well to chemotherapy and underwent surgical excision of the primary tumor, followed by three more courses of chemotherapy.