Clinical translation of a hand-held optical imager for breast cancer diagnostics: In vitro and in vivo tomography studies

Optical imaging is an emerging technology towards non-invasive breast cancer diagnostics. In recent years, portable and patient comfortable hand-held optical imagers are developed towards two-dimensional (2D) tumor detections. However, these imagers are not capable of three-dimensional (3D) tomography because they cannot register the positional information of the hand-held probe onto the imaged tissue. A hand-held optical imager has been developed in our Optical Imaging Laboratory with 3D tomography capabilities, as demonstrated from tissue phantom studies. The overall goal of my dissertation is towards the translation of our imager to the clinical setting for 3D tomographic imaging in human breast tissues. A systematic experimental approach was designed and executed as follows: (i) fast 2D imaging, (ii) coregistered imaging, and (iii) 3D tomographic imaging studies. (i) Fast 2D imaging was initially demonstrated in tissue phantoms (1% Liposyn solution) and in vitro (minced chicken breast and 1% Liposyn). A 0.45 cm3 fluorescent target at 1:0 contrast ratio was detectable up to 2.5 cm deep. Fast 2D imaging experiments performed in vivo with healthy female subjects also detected a 0.45 cm3 fluorescent target superficially placed ∼2.5 cm under the breast tissue. (ii) Coregistered imaging was automated and validated in phantoms with ∼0.19 cm error in the probe’s positional information. Coregistration also improved the target depth detection to 3.5 cm, from multi-location imaging approach. Coregistered imaging was further validated in-vivo , although the error in probe’s positional information increased to ∼0.9 cm (subject to soft tissue deformation and movement). (iii) Three-dimensional tomography studies were successfully demonstrated in vitro using 0.45 cm3 fluorescence targets. The feasibility of 3D tomography was demonstrated for the first time in breast tissues using the hand-held optical imager, wherein a 0.45 cm3 fluorescent target (superficially placed) was recovered along with artifacts. Diffuse optical imaging studies were performed in two breast cancer patients with invasive ductal carcinoma. The images showed greater absorption at the tumor cites (as observed from x-ray mammography, ultrasound, and/or MRI). In summary, my dissertation demonstrated the potential of a hand-held optical imager towards 2D breast tumor detection and 3D breast tomography, holding a promise for extensive clinical translational efforts.

Proton nuclear magnetic resonance investigation of the native and modified active site structure of heme proteins

Hemoproteins are a very important class of enzymes in nature sharing the essentially same prosthetic group, heme, and are good models for exploring the relationship between protein structure and function. Three important hemoproteins, chloroperoxidase (CPO), horseradish peroxidase (HRP), and cytochrome P450cam (P450cam), have been extensively studied as archetypes for the relationship between structure and function. In this study, a series of 1D and 2D NMR experiments were successfully conducted to contribute to the structural studies of these hemoproteins. ^ During the epoxidation of allylbenzene, CPO is converted to an inactive green species with the prosthetic heme modified by addition of the alkene plus an oxygen atom forming a five-membered chelate ring. Complete assignment of the NMR resonances of the modified porphyrin extracted and demetallated from green CPO unambiguously established the structure of this porphyrin as an NIII-alkylated product. A novel substrate binding motif of CPO was proposed from this concluded regiospecific N-alkylation structure. ^ Soybean peroxidase (SBP) is considered as a more stable, more abundant and less expensive substitute of HRP for industrial applications. A NMR study of SBP using 1D and 2D NOE methods successfully established the active site structure of SBP and consequently fills in the blank of the SBP NMR study. All of the hyperfine shifts of the SBP-CN- complex are unambiguously assigned together with most of the prosthetic heme and all proximal His170 resonances identified. The active site structure of SBP revealed by this NMR study is in complete agreement with the recombinant SBP crystal structure and is highly similar to that of the HRP with minor differences. ^ The NMR study of paramagnetic P450cam had been greatly restricted for a long time. A combination of 2D NMR methods was used in this study for P450cam-CN - complexes with and without camphor bound. The results lead to the first unequivocal assignments of all heme hyperfine-shifted signals, together with certain correlated diamagnetic resonances. The observed alternation of the assigned novel proximal cysteine β-CH2 resonances induced by camphor binding indicated a conformational change near the proximal side.^

Nuclear magnetic resonance spectroscopic and computational investigations of chloroperoxidase catalyzed regio- and enantio-selective transformations

Chloroperoxidase (CPO) is the most versatile heme-containing enzyme that catalyzes a broad spectrum of reactions. The remarkable feature of this enzyme is the high regio- and enantio-selectivity exhibited in CPO-catalyzed oxidation reactions. The aim of this dissertation is to elucidate the structural basis for regio- and enantio-selective transformations and investigate the application of CPO in biodegradation of synthetic dyes. ^ To unravel the mechanism of CPO-catalyzed regioselective oxidation of indole, the dissertation explored the structure of CPO-indole complex using paramagnetic relaxation and molecular modeling. The distances between the protons of indole and the heme iron revealed that the pyrrole ring of indole is oriented toward the heme with its 2-H pointing directly at the heme iron. This provides the first experimental and theoretical explanation for the "unexpected" regioselectivity of CPO-catalyzed indole oxidation. Furthermore, the residues including Leu 70, Phe 103, Ile 179, Val 182, Glu 183, and Phe 186 were found essential to the substrate binding to CPO. These results will serve as a lighthouse in guiding the design of CPO mutants with tailor-made activities for biotechnological applications. ^ To understand the origin of the enantioselectivity of CPO-catalyzed oxidation reactions, the interactions of CPO with substrates such as 2-(methylthio)thiophene were investigated by nuclear magnetic resonance spectroscopy (NMR) and computational techniques. In particular, the enantioselectivity is partly explained by the binding orientation of substrates. In third facet of this dissertation, a green and efficient system for degradation of synthetic dyes was developed. Several commercial dyes such as orange G were tested in the CPO-H2O 2-Cl- system, where degradation of these dyes was found very efficient. The presence of halide ions and acidic pH were found necessary to the decomposition of dyes. Significantly, the results revealed that this degradation of azo dyes involves a ferric hypochlorite intermediate of CPO (Fe-OCl), compound X.^

Efeitos in vivo e in vitro de agonistas parciais do receptor NOP: implicações para o tratamento da ansiedade, depressão e mania

Introduction: This study aimed to investigate the effects of the two peptide NOP partial agonists (UFP-113 and [F/G]N/OFQ(1-13)NH2) and the non peptide NOP partial agonist (AT-090) in the mouse emotional behavior as well as in the intracellular transduction pathways following the receptor binding. Methods: Male Swiss or CD-1 mice were used in this study together with NOP(+/+) and NOP(-/-) mice. The elevated plus maze (EPM) was used to evaluate the effects of compounds on anxiety-like behaviors. Diazepam and the NOP agonists, N/OFQ and Ro 65-6570, were used as positive controls in the EPM. NOP(+/+) and NOP(-/-) mice were used to evaluate the selectivity of those compounds that induced anxiolytic-like behaviors. The forced swim test (FST) was used to evaluate the effects of compounds on depressive-like behaviors. Nortriptyline and the NOP antagonists, UFP-101 and SB-612111, were used as positive controls in the FST. The effects of N/OFQ, UFP-101, SB-612111, UFP-113, [F/G]N/OFQ(1-13)NH2, and AT-090 were assessed in the methylphenidate-induced hyperlocomotion (MIH) test; in this assay valproate was used as positive control. The G protein and β-arrestin 2 transduction pathways of NOP receptor agonists (N/OFQ and Ro 65-6570), antagonist (UFP-101), and partial agonists (UFP-113, [F/G]N/OFQ(1-13)NH2, and AT-090) were also evaluated using an innovative assay that measures a bioluminescence resonance energy transfer process. For this, cell lines permanently co-expressing the NOP receptor coupled to luciferase (energy donor), and green fluorescent protein (energy acceptor) coupled to one of the effector proteins (G protein or β-arrestin 2) were used. Results: Diazepam (1 mg/kg), N/OFQ (1 nmol), Ro 65-6570 (0.1 mg/kg), and AT-090 (0.01 mg/kg) induced anxiolytic-like effect in mice in the EPM. The effects of Ro 65-6570 and AT-090 were selective to NOP receptor. UFP-113 (0.01-1 nmol) and [F/G]N/OFQ(1-13)NH2 (0.1-3 nmol) were inactive in the EPM. In the FST, nortriptyline (30 mg/kg), UFP-101 (10 nmol), SB-612111 (10 mg/kg), UFP-113 (0.01 and 0.1 nmol), and [F/G]N/OFQ(1-13)NH2 (0.3 and 1 nmol) induced antidepressant-like effects, while AT-090 (0.001-0.1 mg/kg) was inactive in this assay. The effects of UFP-113 and [F/G]N/OFQ(1-13)NH2 were selective to NOP receptor. Valproate (400 mg/kg) counteracted methylphenidate (MPH, 10 mg/kg)-induced hyperlocomotion in mice in the open field. N/OFQ (1 nmol), UFP-113 (0.01-0.1 nmol), and [F/G]N/OFQ(1-13)NH2 (1 nmol) were also able to reduce the MPH-induced hyperlocomotion, without changing the locomotor activity per se. The effect of UFP-113 was selective to NOP receptor. The UFP-101 (10 nmol), SB-612111 (10 mg/kg), and AT-090 (0.001-0.03 mg/kg) did not change the hyperlocomotor effect of methylphenidate. In vitro, N/OFQ and Ro 65-6570 behaved as NOP full agonists for G-protein and β-arrestin 2 pathways. AT-090 behaved as NOP receptor partial agonist for both transduction pathways, while UFP-113 and [F/G]N/OFQ(1-13)NH2 behaved as partial agonists and antagonists of NOP receptor for NOP/G protein and NOP/β-arrestin 2, respectively. UFP-101 behaved as NOP receptor antagonist for both transduction pathways. Conclusion: NOP ligands producing same effects on NOP/G protein interaction (partial agonism), but with opposite effects on β-arrestin 2 recruitment (partial agonism vs antagonism), can promote different in vivo effects on anxiety and mood as it was observed in the behavioral tests. This work corroborates the potential of NOP receptor as an innovative pharmacological target for the treatment of emotional disorders.

Efeitos in vivo e in vitro de agonistas parciais do receptor NOP: implicações para o tratamento da ansiedade, depressão e mania

Introduction: This study aimed to investigate the effects of the two peptide NOP partial agonists (UFP-113 and [F/G]N/OFQ(1-13)NH2) and the non peptide NOP partial agonist (AT-090) in the mouse emotional behavior as well as in the intracellular transduction pathways following the receptor binding. Methods: Male Swiss or CD-1 mice were used in this study together with NOP(+/+) and NOP(-/-) mice. The elevated plus maze (EPM) was used to evaluate the effects of compounds on anxiety-like behaviors. Diazepam and the NOP agonists, N/OFQ and Ro 65-6570, were used as positive controls in the EPM. NOP(+/+) and NOP(-/-) mice were used to evaluate the selectivity of those compounds that induced anxiolytic-like behaviors. The forced swim test (FST) was used to evaluate the effects of compounds on depressive-like behaviors. Nortriptyline and the NOP antagonists, UFP-101 and SB-612111, were used as positive controls in the FST. The effects of N/OFQ, UFP-101, SB-612111, UFP-113, [F/G]N/OFQ(1-13)NH2, and AT-090 were assessed in the methylphenidate-induced hyperlocomotion (MIH) test; in this assay valproate was used as positive control. The G protein and β-arrestin 2 transduction pathways of NOP receptor agonists (N/OFQ and Ro 65-6570), antagonist (UFP-101), and partial agonists (UFP-113, [F/G]N/OFQ(1-13)NH2, and AT-090) were also evaluated using an innovative assay that measures a bioluminescence resonance energy transfer process. For this, cell lines permanently co-expressing the NOP receptor coupled to luciferase (energy donor), and green fluorescent protein (energy acceptor) coupled to one of the effector proteins (G protein or β-arrestin 2) were used. Results: Diazepam (1 mg/kg), N/OFQ (1 nmol), Ro 65-6570 (0.1 mg/kg), and AT-090 (0.01 mg/kg) induced anxiolytic-like effect in mice in the EPM. The effects of Ro 65-6570 and AT-090 were selective to NOP receptor. UFP-113 (0.01-1 nmol) and [F/G]N/OFQ(1-13)NH2 (0.1-3 nmol) were inactive in the EPM. In the FST, nortriptyline (30 mg/kg), UFP-101 (10 nmol), SB-612111 (10 mg/kg), UFP-113 (0.01 and 0.1 nmol), and [F/G]N/OFQ(1-13)NH2 (0.3 and 1 nmol) induced antidepressant-like effects, while AT-090 (0.001-0.1 mg/kg) was inactive in this assay. The effects of UFP-113 and [F/G]N/OFQ(1-13)NH2 were selective to NOP receptor. Valproate (400 mg/kg) counteracted methylphenidate (MPH, 10 mg/kg)-induced hyperlocomotion in mice in the open field. N/OFQ (1 nmol), UFP-113 (0.01-0.1 nmol), and [F/G]N/OFQ(1-13)NH2 (1 nmol) were also able to reduce the MPH-induced hyperlocomotion, without changing the locomotor activity per se. The effect of UFP-113 was selective to NOP receptor. The UFP-101 (10 nmol), SB-612111 (10 mg/kg), and AT-090 (0.001-0.03 mg/kg) did not change the hyperlocomotor effect of methylphenidate. In vitro, N/OFQ and Ro 65-6570 behaved as NOP full agonists for G-protein and β-arrestin 2 pathways. AT-090 behaved as NOP receptor partial agonist for both transduction pathways, while UFP-113 and [F/G]N/OFQ(1-13)NH2 behaved as partial agonists and antagonists of NOP receptor for NOP/G protein and NOP/β-arrestin 2, respectively. UFP-101 behaved as NOP receptor antagonist for both transduction pathways. Conclusion: NOP ligands producing same effects on NOP/G protein interaction (partial agonism), but with opposite effects on β-arrestin 2 recruitment (partial agonism vs antagonism), can promote different in vivo effects on anxiety and mood as it was observed in the behavioral tests. This work corroborates the potential of NOP receptor as an innovative pharmacological target for the treatment of emotional disorders.

Determination of Biomolecular Interdomain Motions using Nuclear Magnetic Resonance

Biological macromolecules can rearrange interdomain orientations when binding to various partners. Interdomain dynamics serve as a molecular mechanism to guide the transitions between orientations. However, our understanding of interdomain dynamics is limited because a useful description of interdomain motions requires an estimate of the probabilities of interdomain conformations, increasing complexity of the problem.

Staphylococcal protein A (SpA) has five tandem protein-binding domains and four interdomain linkers. The domains enable Staphylococcus aureus to evade the host immune system by binding to multiple host proteins including antibodies. Here, I present a study of the interdomain motions of two adjacent domains in SpA. NMR spin relaxation experiments identified a 6-residue flexible interdomain linker and interdomain motions. To quantify the anisotropy of the distribution of interdomain orientations, we measured residual dipolar couplings (RDCs) from the two domains with multiple alignments. The N-terminal domain was directly aligned by a lanthanide ion and not influenced by interdomain motions, so it acted as a reference frame to achieve motional decoupling. We also applied {\it de novo} methods to extract spatial dynamic information from RDCs and represent interdomain motions as a continuous distribution on the 3D rotational space. Significant anisotropy was observed in the distribution, indicating the motion populates some interdomain orientations more than others. Statistical thermodynamic analysis of the observed orientational distribution suggests that it is among the energetically most favorable orientational distributions for binding to antibodies. Thus, the affinity is enhanced by a pre-posed distribution of interdomain orientations while maintaining the flexibility required for function.

The protocol described above can be applied to other biological systems in general. Protein molecule calmodulin and RNA molecule trans-activation response element (TAR) also have intensive interdomain motions with relative small intradomain dynamics. Their interdomain motions were studied using our method based on published RDC data. Our results were consistent with literature results in general. The differences could be due to previous studies' use of physical models, which contain assumptions about potential energy and thus introduced non-experimental information into the interpretations.

Comparison of two methods for measuring the pubococcygeal line from sagittal-plane magnetic resonance imaging

Aims The pubococcygeal line (PCL) is an important reference line for determining measures of pelvic organ support on sagittal-plane magnetic resonance imaging (MRI); however, there is no consensus on where to place the posterior point of the PCL. As coccyx movement produced during pelvic floor muscle (PFM) contractions may affect other measures, optimal placement of the posterior point is important. This study compared two methods for measuring the PCL, with different posterior points, on T2-weighted sagittal MRI to determine the effect of coccygeal movement on measures of pelvic organ support in older women. Methods MRI of the pelvis was performed in the midsagittal plane, at rest and during PFM contractions, on 47 community-dwelling women 60 and over. The first PCL was measured to the tip of the coccyx (PCLtip) and the second to the sacrococcygeal joint (PCLjnt). Four measures of pelvic organ support were made using each PCL as the reference line: urethrovesical junction height, uterovaginal junction height, M-line and levator plate angle. Results During the PFM contraction the PCLtip shortened and lifted (P < 0.001); the PCLjnt did not change (P > 0.05). The changes in the four measures of pelvic organ support were smaller when measured relative to the PCLtip as compared to those to the PCLjnt (P < 0.001). Conclusions Coccyx movement affected the length and position of the PCLtip, which resulted in underestimates of the pelvic-organ lift produced by the PFM contraction. Therefore, we recommend that the PCL be measured to the sacrococcygeal joint and not to the tip of the coccyx

Suivi par élastographie ultrasonore après réparation endovasculaire d’anévrisme aorto-iliaque : étude de faisabilité in vivo

Les maladies cardiovasculaires sont la première cause de mortalité dans le monde et les anévrismes de l’aorte abdominale (AAAs) font partie de ce lot déplorable. Un anévrisme est la dilatation d’une artère pouvant conduire à la mort. Une rupture d’AAA s’avère fatale près de 80% du temps. Un moyen de traiter les AAAs est l’insertion d’une endoprothèse (SG) dans l’aorte, communément appelée la réparation endovasculaire (EVAR), afin de réduire la pression exercée par le flux sanguin sur la paroi. L’efficacité de ce traitement est compromise par la survenue d’endofuites (flux sanguins entre la prothèse et le sac anévrismal) pouvant conduire à la rupture de l’anévrisme. Ces flux sanguins peuvent survenir à n’importe quel moment après le traitement EVAR. Une surveillance par tomodensitométrie (CT-scan) annuelle est donc requise, augmentant ainsi le coût du suivi post-EVAR et exposant le patient à la radiation ionisante et aux complications des contrastes iodés. L’endotension est le concept de dilatation de l’anévrisme sans la présence d’une endofuite apparente au CT-scan. Après le traitement EVAR, le sang dans le sac anévrismal coagule pour former un thrombus frais, qui deviendra progressivement un thrombus plus fibreux et plus organisé, donnant lieu à un rétrécissement de l’anévrisme. Il y a très peu de données dans la littérature pour étudier ce processus temporel et la relation entre le thrombus frais et l’endotension. L’étalon d’or du suivi post-EVAR, le CT-scan, ne peut pas détecter la présence de thrombus frais. Il y a donc un besoin d’investir dans une technique sécuritaire et moins coûteuse pour le suivi d’AAAs après EVAR. Une méthode récente, l’élastographie dynamique, mesure l’élasticité des tissus en temps réel. Le principe de cette technique repose sur la génération d’ondes de cisaillement et l’étude de leur propagation afin de remonter aux propriétés mécaniques du milieu étudié. Cette thèse vise l’application de l’élastographie dynamique pour la détection des endofuites ainsi que de la caractérisation mécanique des tissus du sac anévrismal après le traitement EVAR. Ce projet dévoile le potentiel de l’élastographie afin de réduire les dangers de la radiation, de l’utilisation d’agent de contraste ainsi que des coûts du post-EVAR des AAAs. L’élastographie dynamique utilisant le « Shear Wave Imaging » (SWI) est prometteuse. Cette modalité pourrait complémenter l’échographie-Doppler (DUS) déjà utilisée pour le suivi d’examen post-EVAR. Le SWI a le potentiel de fournir des informations sur l’organisation fibreuse du thrombus ainsi que sur la détection d’endofuites. Tout d’abord, le premier objectif de cette thèse consistait à tester le SWI sur des AAAs dans des modèles canins pour la détection d’endofuites et la caractérisation du thrombus. Des SGs furent implantées dans un groupe de 18 chiens avec un anévrisme créé au moyen de la veine jugulaire. 4 anévrismes avaient une endofuite de type I, 13 avaient une endofuite de type II et un anévrisme n’avait pas d’endofuite. Des examens échographiques, DUS et SWI ont été réalisés à l’implantation, puis 1 semaine, 1 mois, 3 mois et 6 mois après le traitement EVAR. Une angiographie, un CT-scan et des coupes macroscopiques ont été produits au sacrifice. Les régions d’endofuites, de thrombus frais et de thrombus organisé furent identifiées et segmentées. Les valeurs de rigidité données par le SWI des différentes régions furent comparées. Celles-ci furent différentes de façon significative (P < 0.001). Également, le SWI a pu détecter la présence d’endofuites où le CT-scan (1) et le DUS (3) ont échoué. Dans la continuité de ces travaux, le deuxième objectif de ce projet fut de caractériser l’évolution du thrombus dans le temps, de même que l’évolution des endofuites après embolisation dans des modèles canins. Dix-huit anévrismes furent créés dans les artères iliaques de neuf modèles canins, suivis d’une endofuite de type I après EVAR. Deux gels embolisants (Chitosan (Chi) ou Chitosan-Sodium-Tetradecyl-Sulfate (Chi-STS)) furent injectés dans le sac anévrismal pour promouvoir la guérison. Des examens échographiques, DUS et SWI ont été effectués à l’implantation et après 1 semaine, 1 mois, 3 mois et 6 mois. Une angiographie, un CT-scan et un examen histologique ont été réalisés au sacrifice afin d’évaluer la présence, le type et la grosseur de l’endofuite. Les valeurs du module d’élasticité des régions d’intérêts ont été identifiées et segmentées sur les données pathologiques. Les régions d’endofuites et de thrombus frais furent différentes de façon significative comparativement aux autres régions (P < 0.001). Les valeurs d’élasticité du thrombus frais à 1 semaine et à 3 mois indiquent que le SWI peut évaluer la maturation du thrombus, de même que caractériser l’évolution et la dégradation des gels embolisants dans le temps. Le SWI a pu détecter des endofuites où le DUS a échoué (2) et, contrairement au CT-scan, détecter la présence de thrombus frais. Finalement, la dernière étape du projet doctoral consistait à appliquer le SWI dans une phase clinique, avec des patients humains ayant déjà un AAA, pour la détection d’endofuite et la caractérisation de l’élasticité des tissus. 25 patients furent sélectionnés pour participer à l’étude. Une comparaison d’imagerie a été produite entre le SWI, le CT-scan et le DUS. Les valeurs de rigidité données par le SWI des différentes régions (endofuite, thrombus) furent identifiées et segmentées. Celles-ci étaient distinctes de façon significative (P < 0.001). Le SWI a détecté 5 endofuites sur 6 (sensibilité de 83.3%) et a eu 6 faux positifs (spécificité de 76%). Le SWI a pu détecter la présence d’endofuites où le CT-scan (2) ainsi que le DUS (2) ont échoué. Il n’y avait pas de différence statistique notable entre la rigidité du thrombus pour un AAA avec endofuite et un AAA sans endofuite. Aucune corrélation n’a pu être établie de façon significative entre les diamètres des AAAs ainsi que leurs variations et l’élasticité du thrombus. Le SWI a le potentiel de détecter les endofuites et caractériser le thrombus selon leurs propriétés mécaniques. Cette technique pourrait être combinée au suivi des AAAs post-EVAR, complémentant ainsi l’imagerie DUS et réduisant le coût et l’exposition à la radiation ionisante et aux agents de contrastes néphrotoxiques.

Functional Magnetic Resonance Imaging Neurofeedback and Motor training for Parkinson’s Disease: Randomised Trial

Objective: Real-time functional magnetic resonance imaging (rt-fMRI) neurofeedback (NF) uses feedback of the patient’s own brain activity to self-regulate brain networks which in turn could lead to a change in behaviour and clinical symptoms. The objective was to determine the effect of neurofeedback and motor training and motor training (MOT) alone on motor and non-motor functions in Parkinson’s disease (PD) in a 10-week small Phase I randomised controlled trial. Methods: 30 patients with PD (Hoehn & Yahr I-III) and no significant comorbidity took part in the trial with random allocation to two groups. Group 1 (NF: 15 patients) received rt-fMRI-NF with motor training. Group 2 (MOT: 15 patients) received motor training alone. The primary outcome measure was the Movement Disorder Society – Unified Parkinson’s Disease Rating Scale-Motor scale (MDS-UPDRS-MS), administered pre- and post-intervention ‘off-medication’. The secondary outcome measures were the ‘on-medication’ MDS-UPDRS, the Parkinson’s disease Questionnaire-39, and quantitative motor assessments after 4 and 10 weeks. Results: Patients in the NF group were able to upregulate activity in the supplementary motor area by using motor imagery. They improved by an average of 4.5 points on the MDS-UPDRS-MS in the ‘off-medication’ state (95% confidence interval: -2.5 to -6.6), whereas the MOT group improved only by 1.9 points (95% confidence interval +3.2 to -6.8). However, the improvement did not differ significantly between the groups. No adverse events were reported in either group. Interpretation: This Phase I study suggests that NF combined with motor training is safe and improves motor symptoms immediately after treatment, but larger trials are needed to explore its superiority over active control conditions. Clinical Trial website : Unique Identifier: NCT01867827 URL: https://clinicaltrials.gov/ct2/show/NCT01867827?term=NCT01867827&rank=1

Vibrational characteristics of brain magnetic resonance elastography

This thesis aims to investigate vibrational characteristics of magnetic resonance elastography (MRE) of the brain. MRE is a promising, non-invasive methodology for the mapping of shear stiffness of the brain. A mechanical actuator shakes the brain and generates shear waves, which are then imaged with a special MRI sequence sensitive to sub-millimeter displacements. This research focuses on exploring the profile of vibrations utilized in brain elastography from the standpoint of ultimately investigating nonlinear behavior of the tissue. The first objective seeks to demonstrate the effects of encoding off-frequency vibrations using standard MRE methodologies. Vibrations of this nature can arise from nonlinearities in the system and contaminate the results of the measurement. The second objective is to probe nonlinearity in the dynamic brain system using MRE. A non-parametric decomposition technique, novel to the MRE field, is introduced and investigated.

Tensor Completion for Multidimensional Inverse Problems with Applications to Magnetic Resonance Relaxometry

This thesis deals with tensor completion for the solution of multidimensional inverse problems. We study the problem of reconstructing an approximately low rank tensor from a small number of noisy linear measurements. New recovery guarantees, numerical algorithms, non-uniform sampling strategies, and parameter selection algorithms are developed. We derive a fixed point continuation algorithm for tensor completion and prove its convergence. A restricted isometry property (RIP) based tensor recovery guarantee is proved. Probabilistic recovery guarantees are obtained for sub-Gaussian measurement operators and for measurements obtained by non-uniform sampling from a Parseval tight frame. We show how tensor completion can be used to solve multidimensional inverse problems arising in NMR relaxometry. Algorithms are developed for regularization parameter selection, including accelerated k-fold cross-validation and generalized cross-validation. These methods are validated on experimental and simulated data. We also derive condition number estimates for nonnegative least squares problems. Tensor recovery promises to significantly accelerate N-dimensional NMR relaxometry and related experiments, enabling previously impractical experiments. Our methods could also be applied to other inverse problems arising in machine learning, image processing, signal processing, computer vision, and other fields.

Suivi par élastographie ultrasonore après réparation endovasculaire d’anévrisme aorto-iliaque : étude de faisabilité in vivo

Les maladies cardiovasculaires sont la première cause de mortalité dans le monde et les anévrismes de l’aorte abdominale (AAAs) font partie de ce lot déplorable. Un anévrisme est la dilatation d’une artère pouvant conduire à la mort. Une rupture d’AAA s’avère fatale près de 80% du temps. Un moyen de traiter les AAAs est l’insertion d’une endoprothèse (SG) dans l’aorte, communément appelée la réparation endovasculaire (EVAR), afin de réduire la pression exercée par le flux sanguin sur la paroi. L’efficacité de ce traitement est compromise par la survenue d’endofuites (flux sanguins entre la prothèse et le sac anévrismal) pouvant conduire à la rupture de l’anévrisme. Ces flux sanguins peuvent survenir à n’importe quel moment après le traitement EVAR. Une surveillance par tomodensitométrie (CT-scan) annuelle est donc requise, augmentant ainsi le coût du suivi post-EVAR et exposant le patient à la radiation ionisante et aux complications des contrastes iodés. L’endotension est le concept de dilatation de l’anévrisme sans la présence d’une endofuite apparente au CT-scan. Après le traitement EVAR, le sang dans le sac anévrismal coagule pour former un thrombus frais, qui deviendra progressivement un thrombus plus fibreux et plus organisé, donnant lieu à un rétrécissement de l’anévrisme. Il y a très peu de données dans la littérature pour étudier ce processus temporel et la relation entre le thrombus frais et l’endotension. L’étalon d’or du suivi post-EVAR, le CT-scan, ne peut pas détecter la présence de thrombus frais. Il y a donc un besoin d’investir dans une technique sécuritaire et moins coûteuse pour le suivi d’AAAs après EVAR. Une méthode récente, l’élastographie dynamique, mesure l’élasticité des tissus en temps réel. Le principe de cette technique repose sur la génération d’ondes de cisaillement et l’étude de leur propagation afin de remonter aux propriétés mécaniques du milieu étudié. Cette thèse vise l’application de l’élastographie dynamique pour la détection des endofuites ainsi que de la caractérisation mécanique des tissus du sac anévrismal après le traitement EVAR. Ce projet dévoile le potentiel de l’élastographie afin de réduire les dangers de la radiation, de l’utilisation d’agent de contraste ainsi que des coûts du post-EVAR des AAAs. L’élastographie dynamique utilisant le « Shear Wave Imaging » (SWI) est prometteuse. Cette modalité pourrait complémenter l’échographie-Doppler (DUS) déjà utilisée pour le suivi d’examen post-EVAR. Le SWI a le potentiel de fournir des informations sur l’organisation fibreuse du thrombus ainsi que sur la détection d’endofuites. Tout d’abord, le premier objectif de cette thèse consistait à tester le SWI sur des AAAs dans des modèles canins pour la détection d’endofuites et la caractérisation du thrombus. Des SGs furent implantées dans un groupe de 18 chiens avec un anévrisme créé au moyen de la veine jugulaire. 4 anévrismes avaient une endofuite de type I, 13 avaient une endofuite de type II et un anévrisme n’avait pas d’endofuite. Des examens échographiques, DUS et SWI ont été réalisés à l’implantation, puis 1 semaine, 1 mois, 3 mois et 6 mois après le traitement EVAR. Une angiographie, un CT-scan et des coupes macroscopiques ont été produits au sacrifice. Les régions d’endofuites, de thrombus frais et de thrombus organisé furent identifiées et segmentées. Les valeurs de rigidité données par le SWI des différentes régions furent comparées. Celles-ci furent différentes de façon significative (P < 0.001). Également, le SWI a pu détecter la présence d’endofuites où le CT-scan (1) et le DUS (3) ont échoué. Dans la continuité de ces travaux, le deuxième objectif de ce projet fut de caractériser l’évolution du thrombus dans le temps, de même que l’évolution des endofuites après embolisation dans des modèles canins. Dix-huit anévrismes furent créés dans les artères iliaques de neuf modèles canins, suivis d’une endofuite de type I après EVAR. Deux gels embolisants (Chitosan (Chi) ou Chitosan-Sodium-Tetradecyl-Sulfate (Chi-STS)) furent injectés dans le sac anévrismal pour promouvoir la guérison. Des examens échographiques, DUS et SWI ont été effectués à l’implantation et après 1 semaine, 1 mois, 3 mois et 6 mois. Une angiographie, un CT-scan et un examen histologique ont été réalisés au sacrifice afin d’évaluer la présence, le type et la grosseur de l’endofuite. Les valeurs du module d’élasticité des régions d’intérêts ont été identifiées et segmentées sur les données pathologiques. Les régions d’endofuites et de thrombus frais furent différentes de façon significative comparativement aux autres régions (P < 0.001). Les valeurs d’élasticité du thrombus frais à 1 semaine et à 3 mois indiquent que le SWI peut évaluer la maturation du thrombus, de même que caractériser l’évolution et la dégradation des gels embolisants dans le temps. Le SWI a pu détecter des endofuites où le DUS a échoué (2) et, contrairement au CT-scan, détecter la présence de thrombus frais. Finalement, la dernière étape du projet doctoral consistait à appliquer le SWI dans une phase clinique, avec des patients humains ayant déjà un AAA, pour la détection d’endofuite et la caractérisation de l’élasticité des tissus. 25 patients furent sélectionnés pour participer à l’étude. Une comparaison d’imagerie a été produite entre le SWI, le CT-scan et le DUS. Les valeurs de rigidité données par le SWI des différentes régions (endofuite, thrombus) furent identifiées et segmentées. Celles-ci étaient distinctes de façon significative (P < 0.001). Le SWI a détecté 5 endofuites sur 6 (sensibilité de 83.3%) et a eu 6 faux positifs (spécificité de 76%). Le SWI a pu détecter la présence d’endofuites où le CT-scan (2) ainsi que le DUS (2) ont échoué. Il n’y avait pas de différence statistique notable entre la rigidité du thrombus pour un AAA avec endofuite et un AAA sans endofuite. Aucune corrélation n’a pu être établie de façon significative entre les diamètres des AAAs ainsi que leurs variations et l’élasticité du thrombus. Le SWI a le potentiel de détecter les endofuites et caractériser le thrombus selon leurs propriétés mécaniques. Cette technique pourrait être combinée au suivi des AAAs post-EVAR, complémentant ainsi l’imagerie DUS et réduisant le coût et l’exposition à la radiation ionisante et aux agents de contrastes néphrotoxiques.

Comparison of two methods for measuring the pubococcygeal line from sagittal-plane magnetic resonance imaging

Aims The pubococcygeal line (PCL) is an important reference line for determining measures of pelvic organ support on sagittal-plane magnetic resonance imaging (MRI); however, there is no consensus on where to place the posterior point of the PCL. As coccyx movement produced during pelvic floor muscle (PFM) contractions may affect other measures, optimal placement of the posterior point is important. This study compared two methods for measuring the PCL, with different posterior points, on T2-weighted sagittal MRI to determine the effect of coccygeal movement on measures of pelvic organ support in older women. Methods MRI of the pelvis was performed in the midsagittal plane, at rest and during PFM contractions, on 47 community-dwelling women 60 and over. The first PCL was measured to the tip of the coccyx (PCLtip) and the second to the sacrococcygeal joint (PCLjnt). Four measures of pelvic organ support were made using each PCL as the reference line: urethrovesical junction height, uterovaginal junction height, M-line and levator plate angle. Results During the PFM contraction the PCLtip shortened and lifted (P < 0.001); the PCLjnt did not change (P > 0.05). The changes in the four measures of pelvic organ support were smaller when measured relative to the PCLtip as compared to those to the PCLjnt (P < 0.001). Conclusions Coccyx movement affected the length and position of the PCLtip, which resulted in underestimates of the pelvic-organ lift produced by the PFM contraction. Therefore, we recommend that the PCL be measured to the sacrococcygeal joint and not to the tip of the coccyx

Cerebral misery perfusion diagnosed using hypercapnic blood-oxygenation-level-dependent contrast functional magnetic resonance imaging: a case report

Introduction Cerebral misery perfusion represents a failure of cerebral autoregulation. It is animportant differential diagnosis in post-stroke patients presenting with collapses in the presence of haemodynamically significant cerebrovascular stenosis. This is particularly the case when cortical or internal watershed infarcts are present. When this condition occurs, further investigation should be done immediately. Case presentation A 50-year-old Caucasian man presented with a stroke secondary to complete occlusion of his left internal carotid artery. He went on to suffer recurrent seizures. Neuroimaging demonstrated numerous new watershed-territory cerebral infarcts. No source of arterial thromboembolism was demonstrable. Hypercapnic blood-oxygenation-level-dependent-contrast functional magnetic resonance imaging was used to measure his cerebrovascular reserve capacity. The findings were suggestive of cerebral misery perfusion. Conclusions Blood-oxygenation-level-dependent-contrast functional magnetic resonance imaging allows the inference of cerebral misery perfusion. This procedure is cheaper and more readily available than positron emission tomography imaging, which is the current gold standard diagnostic test. The most evaluated treatment for cerebral misery perfusion is extracranial-intracranial bypass. Although previous trials of this have been unfavourable, the results of new studies involving extracranial-intracranial bypass in high-risk patients identified during cerebral perfusion imaging are awaited. Cerebral misery perfusion is an important and under-recognized condition in which emerging imaging and treatment modalities present the possibility of practical and evidence-based management in the near future. Physicians should thus be aware of this disorder and of recent developments in diagnostic tests that allow its detection.