Computerized axial tomography: estimation of spatial and density resolution capability

Dr Ayub Khan Ommaya (1930-2008): The eventful life of a revolutionary neurosurgeon

Dr Ayub Khan Ommaya (1930-2008) was a pioneering figure in the field of neurosurgery, with a particular focus on traumatic brain injury. As history books have held, he was a man of great intellect and vision, possessing a rare combination of scientific rigour and compassionate empathy. One of Dr Ommaya's most notable contributions was his development of the Ommaya reservoir, a device used to deliver drugs directly into the brain. This groundbreaking technology transformed the treatment of brain tumours and other neurological disorders, enabling clinicians to administer medications with unprecedented precision and efficacy. From his groundbreaking research on traumatic brain injury to his visionary invention of the Ommaya reservoir, Ommaya's legacy continues to inspire and inform the work of countless medical professionals around the world. This historical paper delves into Ommaya's remarkable life story, highlighting his extraordinary contributions to the field of neurosurgery.

Applications of Microct Imaging to Archaeobotanical Research

The potential applications of microCT scanning in the field of archaeobotany are only just beginning to be explored. The imaging technique can extract new archaeobotanical information from existing archaeobotanical collections as well as create new archaeobotanical assemblages within ancient ceramics and other artefact types. The technique could aid in answering archaeobotanical questions about the early histories of some of the world's most important food crops from geographical regions with amongst the poorest rates of archaeobotanical preservation and where ancient plant exploitation remains poorly understood. This paper reviews current uses of microCT imaging in the investigation of archaeobotanical questions, as well as in cognate fields of geosciences, geoarchaeology, botany and palaeobotany. The technique has to date been used in a small number of novel methodological studies to extract internal anatomical morphologies and three-dimensional quantitative data from a range of food crops, which includes sexually-propagated cereals and legumes, and asexually-propagated underground storage organs (USOs). The large three-dimensional, digital datasets produced by microCT scanning have been shown to aid in taxonomic identification of archaeobotanical specimens, as well as robustly assess domestication status. In the future, as scanning technology, computer processing power and data storage capacities continue to improve, the possible applications of microCT scanning to archaeobotanical studies will only increase with the development of machine and deep learning networks enabling the automation of analyses of large archaeobotanical assemblages.

Neurological surgery at the National Institutes of Health

The Surgical Neurology Branch (SNB) in the intramural program of the National Institute of Neurological Disorders and Stroke at the National Institutes of Health has been a unique setting for academic neurosurgery for nearly 60 years. Every patient evaluated and treated in the SNB is enrolled in a clinical research protocol, which underscores a singular focus on advancing neurosurgical research and patient care. Since the inception of the SNB, this research effort has been driven by dedicated clinician-investigators and basic scientists including Maitland Baldwin, Igor Klatzo, John M. Van Buren, Ayub K. Ommaya, Richard J. Youle, and Edward H. Oldfield. These and other SNB investigators have studied and advanced treatment of a number of neuropathologic processes, including delineation of differences between cytotoxic and vasogenic edema, head injury, Cushing disease, the effects of vascular endothelial growth factor in nervous system tissues, tumor suppressor syndromes, the pathophysiology of syringomyelia, mechanisms underlying cerebral vasospasm after subarachnoid hemorrhage, spinal arteriovenous malformations, mechanisms of cell death, and drug delivery. Currently, SNB efforts are focused on central nervous system drug delivery, the natural history of familial tumor syndromes, functional neurosurgery, epilepsy, vasospasm, and development of chemotherapeutics for malignant glioma. Throughout its history, the SNB has also been dedicated to training neurosurgeon clinician-investigators; 23 previous fellows/staff have become chairs of their respective neurosurgical departments. Recently, the commitment to training future neurosurgeon clinician-investigators has been further defined with the development of a residency-training program in neurological surgery approved in 2010.

Correlation of apparent diffusion coefficient and computed tomography density in acute ischemic stroke

BACKGROUND AND PURPOSE

Diffusion-weighted MR imaging is very sensitive for the detection of restricted molecular water diffusion in acute ischemic stroke. CT is sensitive to net water uptake in ischemic edema. We compared the decrease in the apparent diffusion coefficient (ADC) in diffusion-weighted MR imaging with CT density changes to study the correlation between diffusion restriction and water uptake in acute stroke patients.

METHODS

Twenty-five patients with acute ischemic stroke of the anterior cerebral circulation underwent MR and CT imaging 1.3 to 5.4 hours after symptom onset. ADC and CT data were transferred into a common 3-dimensional space, and regions of decreased ADC (dADC) were superimposed onto the corresponding CT. Mean values of ADC and Hounsfield units (HU) were determined in comparison with the nonaffected hemisphere.

RESULTS

Mean decrease in ADC (dADC) was 170+/-53x 10(-6) mm2/s and corresponded to a decrease (dCT) in CT density of 1.3+/-0.7 HU. dCT showed a continuous linear decrease of 0.4 HU/h (r=0.55, P<0.01), whereas the decrease is ADC was almost complete after 1.5 hours. A correlation between the decrease in ADC and dCT was found (r=0.41, P=0.04).

CONCLUSIONS

The severity of diffusion restriction correlates with net water uptake in acute ischemic stroke. However, the underlying pathophysiology and different time courses indicate a common reason rather than a direct causality for both phenomena. The time delay and low value of CT density changes provide a reasonable explanation for the higher sensitivity of MR imaging in ischemic stroke.