As the incidence of diagnosed carpal tunnel syndrome continues to increase, an understanding of the mechanism(s) of insult to the median nerve which leads to its development becomes ever more imperative. Knowledge of the exact cause of CTS could lead to improved diagnostic and treatment methods, or more importantly, to better preventative measures. The goal of this study was to investigate movements and interactions of structures within the carpal tunnel during wrist flexion and hand loading in order to obtain information about a specific mechanism of insult to the median nerve. Symptomatic and normal subjects were compared to observe differences in the interactions of the median nerve and its surrounding structures. A new methodology was developed to facilitate the evaluation of these populations.

Cancer is the second deadliest disease in the United States with an estimated 1.69 million new cases in 2017. Medical imaging modalities, such as computed tomography (CT) and magnetic resonance imaging (MRI), are widely used in clinical medicine to detect, diagnose, plan treatment, and monitor tumors within the body. Advances in imaging research related to cancer assessment have largely relied on consented human patients, often including varied populations and treatments. Tumor bearing mouse models have been highly valued for basic science research, but imaging focused applications are limited by the translational ability of micro imaging systems. Pig models are well suited to bridge the gap between human cohorts and mouse models due to similar anatomy, physiology, life-span, and size between pigs and humans. These models provide the opportunity to advance medical imaging while simultaneously characterizing progressive changes resulting from an intervention, exposure, or genetic modification. We present a foundation for effectively characterizing disease models in pigs, susceptible to tumor development, using longitudinal medical image acquisition and post-processing techniques for quantification of disease. Longitudinal, whole-body protocols were developed with CT and MRI. Focus was placed on systematic process, including transportation, anesthesia and positioning, imaging, and environmental controls. Demonstration of the methodology was achieved with six pigs (30-85 kg) with four to seven imaging time points acquired per animal. Consistent positioning across time points (CT to CT) and within time points (CT to MRI) was assessed with distance measures obtained from the skeleton following rigid registration between images. Alignment across time points was achieved with an average value of 16.51 (± 12.46) mm observed all acquired measurements. For consistent, retrievable, and complete qualitative assessment of acquired images, structured reports were developed, including assessment of imaging quality and emphasis on tumor development throughout the body. Reports were used to perform a systematic, semi-qualitative comparison of CT and MRI lung assessment with an overall agreement of 72% in detection of disease indicators. A multi-level registration algorithm was developed to align anatomic structures of interest in the acquired longitudinal datasets. The algorithm consisted of initialization followed by repeated application of a core registration framework as the input data reduced in image field of view. It was applied to align regions of interest in the brain, upper right lung, and right kidney. Validation was performed with overlap (range = [0.0,1.0], complete overlap = 1) and distance measures (range = [0.0, ∞], perfect match = 0.0) of corresponding segmentations with overall results of 0.85 (± 0.11) and 0.41 (± 0.83) mm, respectively. An extension of the algorithm was created, demonstrating the ability to incorporate directional growth and feature extraction measurements into longitudinal tumor progression monitoring. Techniques were applied to a phantom dataset showing solid tumor growth and transition from a non-solid to part-solid lesion in the lungs. Finally, the developed methods – imaging, structured reporting, registration, and longitudinal feature extraction – were applied to four different porcine models pre-disposed to tumor development. 1) A genetically modified Li-Fraumeni (TP53R167H/+/TP53R167H/R167H) background model showing the development of osteosarcoma and lymphoma. 2) A TP53R167H/+ animal with exposure to crystalline silica showing progression of silicosis in the lungs. 3) TP53R167H/+/TP53R167H/R167H animals with exposure to radiation for targeted sarcoma development and 4) TP53R167H/+ pigs with conditional KRASG12D/+ mutation activated in the lung and pancreas. Whole-body and targeted imaging protocols were developed for each model and qualitatively interpreted by a radiologist using structured reports. Multi-level registration was used to align identified tumors and longitudinal features were extracted to quantitatively track change over time. Overall, the developed methods aided in the effective, non-invasive characterization of these animals.

A mielopatia espondilótica cervical (MEC) é afecção relacionada diretamente com o estreitamento do canal vertebral cervical. O objetivo deste estudo foi avaliar variações morfométricas da coluna vertebral cervical em pacientes portadores de MEC por meio da ressonância magnética dinâmica nas posições neutra, em flexão e em extensão. Este é um estudo prospectivo de pacientes portadores de MEC secundária à doença degenerativa da coluna vertebral cervical. Os parâmetros morfométricos foram avaliados pelas sequências de ressonância magnética ponderadas em T2, no plano sagital em posições neutra, flexão e extensão. Os parâmetros estudados foram o comprimento anterior da medula espinhal (CAME), o comprimento posterior da medula espinhal (CPME), o diâmetro do canal vertebral (DCV) e o diâmetro da medula espinhal (DME). O CAME e o CPME foram mais longo em flexão do que nas posições em neutro e extensão, sendo encontrada diferença estatisticamente significativa entre a posição em flexão e extensão. O DCV e o DME foram maiores em flexão do que nas posições neutra e em extensão, no entanto não foi encontrada diferença estatisticamente significativa quando comparados nas posições em neutro, flexão e extensão. Desta forma, o exame de ressonância magnética dinâmica permite avaliar as variações morfométricas do canal vertebral cervical em pacientes portadores de mielopatia cervical espondilótica. / Cervical spondylotic myelopathy is a condition directly related to the narrowing of the cervical vertebral canal. The objective of this study was to evaluate morphometric variations of the cervical spine in patients with CSM using dynamic magnetic resonance imaging (MRI) in neutral, flexion and extension positions. This is a prospective study of patients with CSM secondary to degenerative disease of the cervical spine. The morphometric parameters were evaluated using T2-weighted MRI sequences in the sagittal plane with neutral, flexion and extension position of the neck. The parameters studied were the anterior length of the spinal cord (ALSC), the posterior length of the spinal cord (PLSC), the diameter of the vertebral canal (DVC) and the diameter of the spinal cord (DSC). The ALSC and PLSC were longer in flexion than extension and neutral position, with statistically significant difference between the flexion and extension position. The DVC and the DSC were greater in flexion than in extension and neutral position, however there was no statistically significant difference when comparing the positions in neutral, flexion and extension. Therefore, dynamic MRI allowed to evaluate morphometric variations in the cervical spinal canal in patients with cervical spondylotic myelopathy.

Obsessive-compulsive disorder (OCD) is associated with diminished quality of life and cognitive control dysfunction. Conflict adaptation is a reflection of cognitive control, and consists of the ability to detect conflict in previous trials and adjust performance on current trials. Conflict adaptation is thought to rely on interplay between the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (dlPFC) for detecting conflict and signaling for increases in control, respectively. We hypothesized that individuals with OCD would show reduced conflict adaptation effects in response times, error rates, ACC activation, and dlPFC activation when compared with healthy control subjects. We also expected diminished conflict adaptation to be associated with poorer quality of life in those with OCD. Nineteen individuals with OCD and twenty psychiatrically-healthy controls completed a Stroop task while response times, error rates, and fMRI data were recorded. 2-Group (OCD, control) x 2-Previous Trial Congruency (congruent, incongruent), x 2-Current Trial Congruency (congruent, incongruent) ANOVAs were conducted for both behavioral and fMRI data. Indices of conflict adaptation were correlated with quality of life scores. There was a significant response time conflict adaptation effect collapsed across groups; however, there were no between-groups interactions or main effects. No error rate conflict adaptation was observed at any level of the analysis. On fMRI analyses, the dlPFC showed increased activation on incongruent relative to congruent trials collapsed across groups; however, no ACC activation differences were observed between current incongruent and congruent trials. Conflict adaptation-related activation was noted in the ACC collapsed across groups. The between-groups ANOVA revealed a significant cluster in the ACC with control participants showing greater ACC, medial prefrontal cortex, and left orbitofrontal cortex conflict adaptation activation-related activation relative to individuals with OCD. No between-groups differences were seen in the dlPFC. Conflict adaptation was not significantly related to quality of life. Individuals with OCD may use different neural processes to achieve similar behavioral results to those of healthy controls. Alternative explanations of conflict adaptation effects such as temporal learning theory are also discussed. Our hypothesized model for the ACC and dlPFC functioning as the evaluative and regulative components of cognitive control was only partly supported. ACC and dlPFC activation appeared to highlight different roles, but these roles may be independent rather than existing in a feedback loop. Although quality of life is significantly diminished in individuals with OCD, this loss of quality of life does not appear to be mediated by conflict adaptation differences.

No description available.

A number of chronic disease and behavioural factors are recognised to increase the risk of cardiovascular and cerebrovascular diseases. These putative ???vascular??? risk factors have increasingly been recognised to increase the risk of cognitive impairment in the absence of clinically manifest ischemic events. Their relationship to structural brain changes has received limited attention. In this dissertation, I used high resolution magnetic resonance image (MRI) to examine two structural features of the brain, regional gray matter (GM) volumes and silent lacunar infarcts, and determined their association with vascular risk factors. I related these to cognitive function in both cross-sectional and longitudinal studies. The work was based on the data of three waves in two healthy cohorts drawn from the PATH Through Life Study, which is a population-based longitudinal study of ageing comprising 3 cohorts aged 20-24, 40-44, and 60-64 years, with about 2500 participants in each cohort. Random subsamples of Wave 1 of the cohort aged 60-64 years (N = 478) and Wave 2 of the 40+ cohort (aged 44-48 years) (N = 411) were examined cross-sectionally for the MRI sub-study. The MRI cohort aged 60-64 years was re-examined 4 years later in Wave 2. These studies showed that vascular risk factors are associated with lower regional GM volumes and this association varies at different ages. In adults aged 44-48 years, individual risk factors did not show a significant relationship with GM volumes, but the Framingham risk score was associated with less GM volumes in a number of brain regions, suggesting an additive effect of the risk factors. In the 60+ cohort, hypertension was independently associated with less regional GM volumes in bilateral medial frontal, right superior frontal, left superior temporal and precentral gyri. The same cohort, when examined in Wave 2, showed the negative association of hypertension with gray matter volumes to be more widespread. These associations were observed in men but not in women in either wave. Sex dimorphism was observed in the younger cohort as well, with greater GM volumes in temporal and occipital cortices, midbrain and cerebellum in men, while less GM volumes in cingulate and parietal cortices in comparison with women. Lacunar infarcts were present in 7.8 % of the 60+ cohort, and asymptomatic new lacunar lesions developed in 0.4 % per year in this group. The prevalence of lacunar infarcts was correlated with hypertension and a steeper decline in mental speed. These series of studies indicate the relationship of vascular risk factors with changes in brain structure and cognitive function in healthy middle-aged adults. It is suggested that modifying these vascular risk factors may protect the brain from silent lesions and cognitive impairment, and that intervention should begin early in life to have a major impact.

The body motion of patients, during magnetic resonance (MR) imaging causes significant artifacts in the reconstructed image. Artifacts are manifested as a motion induced blur and ghost repetitions of the moving structures. which obscure vital anatomical and pathological detail. The techniques that have been proposed for suppressing motion artifacts fall into two major categories. Real-time techniques attempt to prevent the motion from corrupting the data by restricting the data acquisition times or motion of the patients, whereas the post-processing techniques use the information embedded in the corrupted data to restore the image. Most methods currently in widespread use belong to the real-time techniques, however with the advent of fast computing platforms and sophisticated signal processing algorithms, the emergence of post-processing techniques is clearly evident. The post-processing techniques usually demand an appropriate model of the motion. The restoration of the image requires that the motion parameters be determined in order to invert the data degradation process. Methods for the correction of translational motion have been studied extensively in the past. The subject of this thesis encompasses the rotational motion model and the effect of rotational motion on the collected MR data in the spatial frequency space (k-space), which is in general, more complicated than the translational model. Rotational motion artifacts are notably prevalent in MR images of head, brain and limbs. Post-processing techniques for the correction of rotational motion artifacts often involve interpolation and re-gridding of the acquired data in the k-space. These methods create significant data overlap and void regions. Therefore, in the past, proposed corrective techniques have been limited to suppression of artifacts caused by small angle rotations. This thesis presents a method of managing overlap regions, using weighted averaging of redundant data, in order to correct for large angle rotations. An iterative estimation technique for filling the data void regions has also been developed by the use of iterated application of projection operators onto constraint sets. These constraint sets are derived from the k-space data generated by the MR imager, and available a priori knowledge. It is shown that the iterative algorithm diverges at times from the required image, due to inconsistency among the constraint sets. It is also shown that this can be overcome by using soft. constraint sets and fuzzy projections. One of the constraints applied in the iterative algorithm is the finite support of the imaged object, marked by the outer boundary of the region of interest (ROI). However, object boundary extraction directly from the motion affected MR image can be difficult, specially if the motion function of the object is unknown. This thesis presents a new ROI extraction scheme based on entropy minimization in the image background. The object rotation function is usually unknown or unable to be measured with sufficient accuracy. The motion estimation algorithm proposed in this thesis is based on maximizing the similarity among the k-space data subjected to angular overlap. This method is different to the typically applied parameter estimation technique based on minimization of pixel energy outside the ROI, and has higher efficiency and ability to estimate rotational motion parameters in the midst of concurrent translational motion. The algorithms for ROI extraction, rotation estimation and data correction have been tested with both phantom images and spin echo MR images producing encouraging results.

<p>In the human body, turbulent flow is associated with many complications. Turbulence typically occurs downstream from stenoses and heart valve prostheses and at branch points of arteries. A proper way to study turbulence may enhance the understanding of the effects of stenoses and improve the functional assessment of damaged heart valves and heart valve prostheses.</p><p>The methods of today for studying turbulence in the human body lack in either precision or speed. This thesis exploits a magnetic resonance imaging (MRI) phenomenon referred to as signal loss in order to develop a method for estimating turbulence intensity in blood flow.</p><p>MRI measurements were carried out on an appropriate flow phantom. The turbulence intensity results obtained by means of the proposed method were compared with previously known turbulence intensity results. The comparison indicates that the proposed method has great potential for estimation of turbulence intensity.</p>

<p>Magnetic Resonance Imaging is an established technology for both imaging and</p><p>functional studies in clinical and research environments. The field is still very</p><p>research intense. Two major research areas are acquisition time and signal quality.</p><p>The last decade has provided tools for more efficient possibilities of trading these</p><p>factors against each other through parallel imaging.</p><p>In this thesis one parallel imaging method, Sensitivity Encoding for fast</p><p>MRI (SENSE) is examined. An alternative solution CCASENSE is developed.</p><p>CCASENSE reduces the acquisition time by estimating the sensitivity maps required</p><p>for SENSE to work instead of running a reference scan. The estimation</p><p>process is done by Blind Source Separation through Canonical Correlation Analysis.</p><p>It is shown that CCASENSE appears to estimate the sensitivity maps better</p><p>than ICASENSE which is a similar algorithm.</p>

<p><b>VLBW adolescents</b></p><p>We found that the VLBW adolescents had specific emotional and cognitive traits. Some of them fit with psychiatric concepts and others do not. They had an increased risk of developing psychiatric symptoms and disorders compared with controls, especially attention deficit, anxiety and relational problems affecting their social skills and overall functioning. Academic achievement was reduced. The attention problems were widespread, but only a minority fulfilled the diagnostic criteria of Attentiondeficit/ hyperactivity disorder. Increased prevalence of anxiety symptoms and disorders may be due to a number of factors, comprising both biological/neuroendocrine and psychosocial mechanisms. The peer problems and deficits in social skills may indicate specific difficulties in relating and adjusting to others, with deficits in comprehending the subtle cues of social relations. The implication of thought problems reported by teachers is unclear. Adolescents with birth weight ≤ 1000 g showed a tendency towards more psychiatric disorders than those with birth weight between 1000 and 1500 g. The lack of gender differences demonstrates that prematurity exceeds the usual effect of gender regarding vulnerability for developing psychiatric symptoms.</p><p>We found that the VLBW adolescents perceived self-esteem and quality of life as others did at the age of 14. However, parents reported functional disadvantages and reduced quality of life measures for their adolescents. The parents worried more for their children’s functioning and well-being, especially if the child had a psychiatric disorder or cerebral palsy. Still, being born VLBW did not influence the warmth in the parent-child relationship, nor did the parents have more mental health problems.</p><p>As the association between VLBW and psychiatric problems could not be explained by SES or the parents’ mental health, a biological cause-effect relationship seems plausible. The frequency of cerebral MRI abnormalities was higher in the VLBW group than in the control group. Furthermore, ADHD symptoms were associated with white matter reduction and thinning of the corpus callosum, while other psychiatric symptoms were not associated with MRI abnormalities. These results support the hypothesis of a specific (“pure”) type of ADHD with a dominant neurological aetiology, while interacting psychosocial experiences play a minor part. Our study indicates that being born VLBW involves a biological vulnerability with increased risk of psychiatric symptoms.</p><p><b>SGA adolescents</b></p><p>Although every fifth SGA adolescent had psychiatric symptoms, assessed by interview, the prevalence of symptoms and disorders did not differ significantly from controls. Yet, screening questionnaires displayed more behavioural problems, lowered social competence and a tendency towards attention deficit/hyperactivity. Teachers reported withdrawal and thought problems, while academic performance did not differ from controls. Boys had more attention and externalizing problems than girls.</p><p>Generally, on psychiatric measures, the term SGA group seemed to fall inbetween the VLBW and the control group, resembling the control group more than the VLBW group.</p><p>The SGA adolescents and their parents reported self-esteem and quality of life as in the control group. Being born SGA at term did not influence the warmth in the parent-child relationship, and the parents did not have more mental health problems than others. The frequency of cerebral MRI abnormalities in the SGA group did not differ from the control group, and no associations were found between psychiatric symptoms and MRI abnormalities.</p> / Paper V reprinted with kind permission of Elsevier, sciencedirect.com