Characterization of structural bone properties through portable single-sided nmr devices: State of the art and future perspectives

Nuclear Magnetic Resonance (NMR) is a well-suited methodology to study bone composition and structural properties. This is because the NMR parameters, such as the T2 relaxation time, are sensitive to the chemical and physical environment of the1H nuclei. Although magnetic resonance imaging (MRI) allows bone structure assessment in vivo, its cost limits the suitability of conventional MRI for routine bone screening. With difficulty accessing clinically suitable exams, the diagnosis of bone diseases, such as osteoporosis, and the associated fracture risk estimation is based on the assessment of bone mineral density (BMD), obtained by the dual-energy X-ray absorptiometry (DXA). However, integrating the information about the structure of the bone with the bone mineral density has been shown to improve fracture risk estimation related to osteoporosis. Portable NMR, based on low-field single-sided NMR devices, is a promising and appealing approach to assess NMR properties of biological tissues with the aim of medical applications. Since these scanners detect the signal from a sensitive volume external to the magnet, they can be used to perform NMR measurement without the need to fit a sample inside a bore of a magnet, allowing, in principle, in vivo application. Techniques based on NMR single-sided devices have the potential to provide a high impact on the clinical routine because of low purchasing and running costs and low maintenance of such scanners. In this review, the development of new methodologies to investigate structural properties of trabecular bone exploiting single-sided NMR devices is reviewed, and current limitations and future perspectives are discussed

New Technology and Techniques for Needle-Based Magnetic Resonance Image-Guided Prostate Focal Therapy

The most common diagnosis of prostate cancer is that of localized disease, and unfortunately the optimal type of treatment for these men is not yet certain. Magnetic resonance image (MRI)-guided focal laser ablation (FLA) therapy is a promising potential treatment option for select men with localized prostate cancer, and may result in fewer side effects than whole-gland therapies, while still achieving oncologic control. The objective of this thesis was to develop methods of accurately guiding needles to the prostate within the bore of a clinical MRI scanner for MRI-guided FLA therapy. To achieve this goal, a mechatronic needle guidance system was developed. The system enables precise targeting of prostate tumours through angulated trajectories and insertion of needles with the patient in the bore of a clinical MRI scanner. After confirming sufficient accuracy in phantoms, and good MRI-compatibility, the system was used to guide needles for MRI-guided FLA therapy in eight patients. Results from this case series demonstrated an improvement in needle guidance time and ease of needle delivery compared to conventional approaches. Methods of more reliable treatment planning were sought, leading to the development of a systematic treatment planning method, and Monte Carlo simulations of needle placement uncertainty. The result was an estimate of the maximum size of focal target that can be confidently ablated using the mechatronic needle guidance system, leading to better guidelines for patient eligibility. These results also quantified the benefit that could be gained with improved techniques for needle guidance

Patterns of injury and violence in Yaoundé Cameroon: an analysis of hospital data.

BackgroundInjuries are quickly becoming a leading cause of death globally, disproportionately affecting sub-Saharan Africa, where reports on the epidemiology of injuries are extremely limited. Reports on the patterns and frequency of injuries are available from Cameroon are also scarce. This study explores the patterns of trauma seen at the emergency ward of the busiest trauma center in Cameroon's capital city.Materials and methodsAdministrative records from January 1, 2007, through December 31, 2007, were retrospectively reviewed; information on age, gender, mechanism of injury, and outcome was abstracted for all trauma patients presenting to the emergency ward. Univariate analysis was performed to assess patterns of injuries in terms of mechanism, date, age, and gender. Bivariate analysis was used to explore potential relationships between demographic variables and mechanism of injury.ResultsA total of 6,234 injured people were seen at the Central Hospital of Yaoundé's emergency ward during the year 2007. Males comprised 71% of those injured, and the mean age of injured patients was 29 years (SD = 14.9). Nearly 60% of the injuries were due to road traffic accidents, 46% of which involved a pedestrian. Intentional injuries were the second most common mechanism of injury (22.5%), 55% of which involved unarmed assault. Patients injured in falls were more likely to be admitted to the hospital (p < 0.001), whereas patients suffering intentional injuries and bites were less likely to be hospitalized (p < 0.001). Males were significantly more likely to be admitted than females (p < 0.001)DiscussionPatterns in terms of age, gender, and mechanism of injury are similar to reports from other countries from the same geographic region, but the magnitude of cases reported is high for a single institution in an African city the size of Yaoundé. As the burden of disease is predicted to increase dramatically in sub-Saharan Africa, immediate efforts in prevention and treatment in Cameroon are strongly warranted

Analysis of Energy Relations between Noise and Vibration Produced by a Low-Field MRI Device

Magnetic resonance imaging (MRI) tomography is often used for noninvasive scanning of various parts of a human body without undesirable effects present in X-ray computed tomography. In MRI devices, slices of a tested subject are selected in 3D coordinates by a system of gradient coils. The current flowing through these coils changes rapidly, which results in mechanical vibration. This vibration is significant also in the equipment working with a low magnetic field, and it causes image blurring of thin layer samples and acoustic noise significantly degrading a speech signal recorded simultaneously during MR scanning of the vocal tract. There are always negative physiological and psychological effects on a person exposed to vibration and acoustic noise. In order to minimize these negative impacts depending on intensity and time duration of exposition, we mapped relationship between energy of vibration and noise signals measured in the MRI scanning area and its vicinity

Creation of a low-cost magnetic resonance system for the early detection of preeclampsia

The placenta is a temporary organ that develops after the implantation of a fertilized egg in the uterus, and it functions as an interface between the mother and the foetus to provide sufficient foetus nutrition. Various studies have shown that the magnetic resonance relaxation times of the placenta change during pregnancy, which could be an early indicator of a disease, such as preeclampsia (PE). However, magnetic resonance imaging (MRI) is not a suitable routine for pregnant women due to cost and availability. Low-field unilateral nuclear magnetic resonance (NMR) is a low-cost alternative capable of measuring relaxation times at a single point in space. Although the frequently adopted ultrasound imaging offers an easy technique to locate the placenta, it does not have the potential for early diagnosis of diseases like PE. Therefore, combining the two modalities, (ultrasound and low-field NMR) opens up a novel diagnostic approach at a much lower cost. This thesis aims to develop a low-field unilateral NMR system capable of measuring the relaxation time parameters at a distance from the sensor surface equivalent to the human placenta position. This study reports the development of a low-field magnetic resonance system, called NMR-CAPIBarA (Clinical Assessment of Patients Implemented with Bar magnet Arrays), capable of measuring spin-lattice relaxation time (T1) and effective transverse relaxation time (Teff2 ) covering the whole range of values relevant to the developing placenta. Two different materials were used to mimic the placental tissue relaxation time values presented in previous literature: PDMS silicone oils representing Teff2 and full-fat milk powder solution representing T1. The low-field electronic system was operated at a magnetic field of 18 mT and was successful in generating and detecting NMR signals using two types of radiofrequency coils: a solenoid and a printed circuit board surface coil, paired with the constructed planar magnet. The most significant result is the positive correlation between the relaxation times measured on the developed system when compared to the same measurements made by a commercial MRI scanner. In particular, the values obtained from the different silicone oil viscosities showed the capability of the low-field system to provide quantitative relaxation measurements over a range of required values to predict the health of the placenta, assuring that the proposed diagnostic approach is quite promising

Effects of dance therapy on balance, gait and neuro-psychological performances in patients with Parkinson's disease and postural instability

Postural Instability (PI) is a core feature of Parkinson’s Disease (PD) and a major cause of falls and disabilities. Impairment of executive functions has been called as an aggravating factor on motor performances. Dance therapy has been shown effective for improving gait and has been suggested as an alternative rehabilitative method. To evaluate gait performance, spatial-temporal (S-T) gait parameters and cognitive performances in a cohort of patients with PD and PI modifications in balance after a cycle of dance therapy

Biomarkers of mismatch repair deficiency in colorectal cancer and cancer predisposition syndromes

PhD ThesisColorectal cancer (CRC) is the third most common cancer in Western societies and approximately 15% are mismatch repair deficient (MMRd). MMRd CRCs have a distinct prognosis, respond to immunotherapy, and occur at a high rate in patients with Lynch syndrome or constitutional mismatch repair deficiency (CMMRD). Detection of MMR deficiency, therefore, guides treatment and identification of associated cancerpredisposition syndromes. However, there is a need for novel biomarkers to detect MMRd CRC, and innovative assays to improve Lynch syndrome and CMMRD diagnosis. I assessed autoantibodies generated against MMRd CRCs as a liquid-biopsy biomarker for cancer detection, by analysing the sera of 464 Lynch syndrome gene carriers using a recently published, multiplex method. Although autoantibodies correlated with a history of CRC, a lack of signal from patients who developed CRC shortly after sampling suggests the method has poor sensitivity. Microsatellite instability (MSI) is an established biomarker of MMR deficiency. I used single molecule molecular inversion probes to develop a sequencing-based MSI assay with an automated results analysis, suitable as a companion diagnostic for immunotherapy, and for streamlined Lynch syndrome screening. The assay achieved 100% accuracy in 197 CRCs, and was robust to sample variables, including quantity, quality, and tumour cell content. Subsequently, I adapted the MSI assay to detect low-level MSI in non-neoplastic tissues of CMMRD patients. The assay separated all 32 CMMRD patients from 94 controls. For both CRC and CMMRD diagnostics, the MSI assay is cheaper and faster than current methods, and is scalable to large cohorts. These results suggest that the humoral immune response to MMRd CRCs cannot readily be used as a biomarker to detect disease, and that alternatives should be sought. However, the MSI assay could be deployed into clinical practice to meet the high demand for MMR deficiency testing of CRCs and to improve CMMRD diagnostics.the Barbour Foundatio