Role of diffusion tensor imaging in early detection of cervical spondylotic myelopathy.

To (1) obtain microstructural parameters (Fractional Anisotropy: FA, Mean Diffusivity: MD) of the cervical spinal cord in patients suffering from cervical spondylotic myelopathy (CSM) using tractography, (2) to compare DTI parameters with the clinical assessment of these patients (3) and with information issued from conventional sequences. FA values were significantly correlated with some of the patients’ clinical scores. High signal intensity of the spinal cord on T2 was not correlated either with the DTI parameters or with the clinical assessment, suggesting that FA is more sensitive than T2 imaging

The development of a patient reported outcome measure and imaging modalities in the evaluation of haemorrhoidal disease

With the advent of DGHAL and PPH, treatments that purport to work by disrupting the arterial supply of haemorrhoids, there has been resurgence in interest in the vascular theory of pathogenesis of haemorrhoids. Despite uncertainty surrounding recurrence and complication rates there has been significant uptake of the new surgical approach due to decreased post-operative pain. However this has not been matched by discussion or evaluation of how haemorrhoidal disease and successful outcome should be evaluated. This thesis evaluates different approaches to the measurement of the burden of haemorrhoidal disease to the patient. A patient reported outcome measure was designed, administered and evaluated by the investigator. Reliability, reproducibility, validity, responsiveness and acceptability have been demonstrated. Three-dimensional ultrasound was used to acquire volumetric data and power Doppler angiography from the anal canal, which was shown to be reliable. Measures of power Doppler angiography were shown to be significantly lower in healthy volunteers than in patients. This technique represents promising value as an outcome measure of haemorrhoidal disease. A dual isotope-surgical nuclear probe technique attempted to measure change in volume of haemorrhoids following rubber band ligation, however consistent results were not obtained. Magnetic resonance imaging was able to demonstrate anal cushions and haemorrhoids, and the feasibility of this method has been demonstrated

The development of a patient reported outcome measure and imaging modalities in the evaluation of haemorrhoidal disease

With the advent of DGHAL and PPH, treatments that purport to work by disrupting the arterial supply of haemorrhoids, there has been resurgence in interest in the vascular theory of pathogenesis of haemorrhoids. Despite uncertainty surrounding recurrence and complication rates there has been significant uptake of the new surgical approach due to decreased post-operative pain. However this has not been matched by discussion or evaluation of how haemorrhoidal disease and successful outcome should be evaluated. This thesis evaluates different approaches to the measurement of the burden of haemorrhoidal disease to the patient. A patient reported outcome measure was designed, administered and evaluated by the investigator. Reliability, reproducibility, validity, responsiveness and acceptability have been demonstrated. Three-dimensional ultrasound was used to acquire volumetric data and power Doppler angiography from the anal canal, which was shown to be reliable. Measures of power Doppler angiography were shown to be significantly lower in healthy volunteers than in patients. This technique represents promising value as an outcome measure of haemorrhoidal disease. A dual isotope-surgical nuclear probe technique attempted to measure change in volume of haemorrhoids following rubber band ligation, however consistent results were not obtained. Magnetic resonance imaging was able to demonstrate anal cushions and haemorrhoids, and the feasibility of this method has been demonstrated

The Brain at Altitude: The Cerebral Vasculature, Hypoxia and Headache

This thesis studies the effect of hypoxia (at rest and during exercise) on the arterial and venous cerebral circulation, investigating the venous system role in high altitude headache. Methods: 1) Hypobaric hypoxic studies investigated 198 trekkers and 24 Investigators to 5300m, 14 to 6400m and 8 to 8848m. 2) Normobaric hypoxic studies used Magnetic Resonance Imaging (MRI)) at sea-level. Four domains were addressed: i. Arterial: Hypobaric hypoxia: (n=24) Transcranial Doppler (TCD) measured middle cerebral artery diameter (MCAD) and blood velocity (MCAv). Sea-Level normobaric hypoxia: (n=7) A hypoxicator (FiO2 = 11%) for 3 hours with a 3Tesla MRI scan measured MCAD and MCAv. ii. Brain Oxygenation: Near Infrared Spectroscopy (NIRS) monitored Regional Brain Oxygenation (rSO2). iii. Venous: Retinal imaging at altitude and MRI at sea-level assessed the venous system. iv. Headache: A daily diary recorded headache burden. Results: Arterial: Hypobaric and normobaric hypoxia induced MCA dilatation. Mean (±(SEM)) MCAD increased in hypoxia (from 5.23(±0.23)mm (at 5300m) to 9.34(±0.88)mm (at 7950m)(p<0.001) (TCD). At sea-level, (after 3 hours FiO2 = 11%) MCAD increased from 3.04(±0.13)mm to 3.27(±0.13)mm (MRI). Brain Oxygenation: rSO2 decreased more than peripheral arterial saturation (SaO2), especially during exercise. The relative percentage reduction in resting SaO2 and rSO2 from 75m to 5300m was -22.23 ±0.56% and -30.61 ±1.28% (p<0.001) respectively. Venous: Hypoxia induced retinal and cerebral venous distension. Twenty-three of 24 subjects exhibited retinal venous distension (range 5 to 44%). Degree of distension correlated with headache (r = 0.553, p=0.005). Possession of a narrow transverse sinus strongly related to retinal and cerebral venous distension and headache. Headache: Headache Severity Index (HSI) (headache score x duration) correlated inversely to both lateral and third ventricular volumes summed (r = -0.5, p = 0.005) and pericerebellar CSF volume (r = -0.56, p = 0.03). Conclusions: Large cerebral arteries dilate and veins distend with hypoxia. This suggests an important influence of cerebral venous anatomy and physiology on headache, with implications for pathophysiological states and their management

Systems Radiology and Personalized Medicine

Medicine has evolved into a high level of specialization using the very detailed imaging of organs. This has impressively solved a multitude of acute health-related problems linked to single-organ diseases. Many diseases and pathophysiological processes, however, involve more than one organ. An organ-based approach is challenging when considering disease prevention and caring for elderly patients, or those with systemic chronic diseases or multiple co-morbidities. In addition, medical imaging provides more than a pretty picture. Much of the data are now revealed by quantitating algorithms with or without artificial intelligence. This Special Issue on “Systems Radiology and Personalized Medicine” includes reviews and original studies that show the strengths and weaknesses of structural and functional whole-body imaging for personalized medicine

Environmental contaminants, parasitism, and neoplasia in white perch Morone americana from Chesapeake Bay, USA

White perch are an abundant demersal fish species in freshwater and oligohaline habitats of the Chesapeake Bay. An avoidance of salinity \u3e 12-15 ppt generally restricts the distribution and movements of fish to within tributaries in the mid to lower Bay, which over time has resulted in the formation of at least three separate stocks in Chesapeake Bay. Sub-populations of white perch that are partially isolated may serve as sentinels of the conditions or stressors in the tributaries in which they reside. Fish are exposed to a variety of environmental contaminants and other anthropogenic stressors that can vary in magnitude based on regional differences in land-use patterns. Health studies of white perch conducted in the 1980s and 1990s revealed a variety of hepatic lesions, including two reports of liver neoplasms, which suggested a sensitivity to degraded habitat or pollution. However, surveys to determine prevalences and potential etiologies of tumors were not determined and the health of white perch in Chesapeake Bay was not investigated again until the studies reported herein. Recent health investigations has revealed associations between neoplasms (cholangiocarcinomas) and bile duct parasites (coccidian and myxozoan) that were not previously described from white perch. These findings raised questions concerning the potential roles of contaminants and parasitism in liver tumor induction in this species. To address knowledge gaps associated with the prevalence and etiology of tumors in white perch, an assessment of environmental contaminants, biomarkers of exposure, biliary parasites, and liver histopathology was required. This study was conducted in two tributaries of the Bay: the Choptank River, an eastern shore tributary with extensive watershed agriculture, and the Severn River, a western shore tributary with extensive development. This dissertation addresses: 1) descriptions and taxonomic placement of the coccidian and myxozoan parasites; 2) measurement of waterborne concentrations of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides, and brominated diphenyl ethers; 3) detection of biliary metabolites as a biomarker of exposures to PAHs; 4) a histopathological description of parasitic infections, neoplasms and other lesions in the liver of fish; 5) an assessment of the biological and anthropogenic risk factors for neoplasia; and 6) an assessment of splenic and hepatic macrophage aggregates as an alternate biomarker of contaminant exposure

Histopathology of Aquatic Animals

Histopathological studies of aquatic animals refer to the microscopic examination of tissues and organs in order to detect deviations from the expected microscopic or macroscopic structure. Information obtained from the study of histomorphological lesions in aquatic animals can be a useful addition when determining the general state of health of aquatic animals, especially if chronic stressors and/or pathogens are present. Compared to mammals, postmortem autolysis progresses very rapidly in most aquatic organisms. This fact makes histopathological examination quite complex and demanding, not only in a histotechnical sense. A prerequisite for a successful study is the baseline knowledge of physiological processes and histological architecture of the studied species. Therefore, the aim of this Special Issue is to contribute to the current state of knowledge on the histopathology of aquatic animals and to provide a professional and encyclopedic tool for biologists and veterinarians

Seventh Annual Workshop on Space Operations Applications and Research (SOAR 1993), volume 2

This document contains papers presented at the Space Operations, Applications and Research Symposium (SOAR) Symposium hosted by NASA/Johnson Space Center (JSC) and cosponsored by NASA/JSC and U.S. Air Force Materiel Command. SOAR included NASA and USAF programmatic overviews, plenary session, panel discussions, panel sessions, and exhibits. It invited technical papers in support of U.S. Army, U.S. Navy, Department of Energy, NASA, and USAF programs in the following areas: robotics and telepresence, automation and intelligent systems, human factors, life support, and space maintenance and servicing. SOAR was concerned with Government-sponsored research and development relevant to aerospace operations

An investigation into the effects of commencing haemodialysis in the critically ill

&lt;b&gt;Introduction:&lt;/b&gt; We have aimed to describe haemodynamic changes when haemodialysis is instituted in the critically ill. 3 hypotheses are tested: 1)The initial session is associated with cardiovascular instability, 2)The initial session is associated with more cardiovascular instability compared to subsequent sessions, and 3)Looking at unstable sessions alone, there will be a greater proportion of potentially harmful changes in the initial sessions compared to subsequent ones. &lt;b&gt;Methods:&lt;/b&gt; Data was collected for 209 patients, identifying 1605 dialysis sessions. Analysis was performed on hourly records, classifying sessions as stable/unstable by a cutoff of &gt;+/-20% change in baseline physiology (HR/MAP). Data from 3 hours prior, and 4 hours after dialysis was included, and average and minimum values derived. 3 time comparisons were made (pre-HD:during, during HD:post, pre-HD:post). Initial sessions were analysed separately from subsequent sessions to derive 2 groups. If a session was identified as being unstable, then the nature of instability was examined by recording whether changes crossed defined physiological ranges. The changes seen in unstable sessions could be described as to their effects: being harmful/potentially harmful, or beneficial/potentially beneficial. &lt;b&gt;Results:&lt;/b&gt; Discarding incomplete data, 181 initial and 1382 subsequent sessions were analysed. A session was deemed to be stable if there was no significant change (&gt;+/-20%) in the time-averaged or minimum MAP/HR across time comparisons. By this definition 85/181 initial sessions were unstable (47%, 95% CI SEM 39.8-54.2). Therefore Hypothesis 1 is accepted. This compares to 44% of subsequent sessions (95% CI 41.1-46.3). Comparing these proportions and their respective CI gives a 95% CI for the standard error of the difference of -4% to 10%. Therefore Hypothesis 2 is rejected. In initial sessions there were 92/1020 harmful changes. This gives a proportion of 9.0% (95% CI SEM 7.4-10.9). In the subsequent sessions there were 712/7248 harmful changes. This gives a proportion of 9.8% (95% CI SEM 9.1-10.5). Comparing the two unpaired proportions gives a difference of -0.08% with a 95% CI of the SE of the difference of -2.5 to +1.2. Hypothesis 3 is rejected. Fisher’s exact test gives a result of p=0.68, reinforcing the lack of significant variance. &lt;b&gt;Conclusions:&lt;/b&gt; Our results reject the claims that using haemodialysis is an inherently unstable choice of therapy. Although proportionally more of the initial sessions are classed as unstable, the majority of MAP and HR changes are beneficial in nature