Hipotrofía nos músculos que estabilizam a coluna tem sido identificada nos pacientes com lombalgia. Entretanto, não se sabe se a perda muscular é causa ou conseqüência desta disfunção, nem se ela é influenciada pelo tipo de alteração discal que o indivíduo apresenta. Este estudo testou a hipótese de que a hipotrofía dos pacientes com lombalgia seja dependente do tipo de alteração discal. Para avaliar a condição muscular em diferentes tipos de alteração discal, optou-se por um estudo retrospectivo e por uma seleção aleatória de 78 exames de ressonância magnética de indivíduos com lombalgia. Em cada exame foram realizadas medidas quantitativas da porcentagem de gordura na área de secção transversa dos mm. multífidus e psoas, nos três últimos níveis da coluna lombar. A alteração discal foi encontrada em 95% dos exames, sendo o abaulamento o achado de imagem mais freqüente, seguido pela protrusão discal. A porcentagem de gordura variou conforme o tipo de alteração discal. Nos níveis com abaulamento há em ambos os músculos estudados 6% a mais de tecido gorduroso do que nos níveis onde há protrusão e esta diferença foi estatisticamente significante. Músculos nos níveis onde há protrusão sem fissura no anel fibroso apresentaram maior substituição gordurosa do que aqueles onde há protrusão com fissura. A porcentagem de gordura foi influenciada por características anatômicas como músculo estudado e nível da coluna, e por características como idade e sexo dos sujeitos. Estes resultados indicam que a hipotrofía muscular em pacientes com lombalgia não é um processo uniforme e generalizado, mas sim correlacionado a diferentes variáveis, entre elas o tipo de alteração discal que o paciente apresenta. / Low back pain patients present atrophy on muscles responsible for spine stabilization. However, it is not clear if muscle waste is related to the cause or if it is a consequence of this disfunction. Nor it is clear if muscle athophy is affected by the type of disc pathology. This study tested the hypothesis that muscle waste in low back pain patients influenced by the type of disc derangement. Magnetic resonance scans of 78 low back pain patients were randomly analysed. Cross sectional area percentage of fat tissue in multifidi and psoas major muscles was measured on the lower levels of the lumbar spine. Disc pathology was found in 95% of the exams and disc bulge was the most frequent abnormality, followed by disc protrusion. Fat percentage varied according to disc pathology and this difference was statistically significant. Muscles on levels with disc bulge presented 6% more fat deposits than muscles on levels with disc protrusion. Muscles on levels with discs without anular tear present more fat infiltration than muscles on levels with anular tear. Fat percentage was also influenced by anatomic aspects such as evaluated muscle and spine level, and sample characteristics as age and sex. The results indicated that muscle atrophy in low back pain patients is not a uniform and generalized feature. It is correlated to different variables, such as type of disc pathology

O tratamento da afecção de disco intervertebral tóraco-lombar com eletroacupuntura tem o objetivo de analgesia e reabilitação motora e sensorial. As melhoras funcionais observadas após lesão medular decorrem de fenômenos de plasticidade sináptica, correspondendo a um mecanismo compensatório e não de reparo estrutural. S100&beta; é considerado um fator neurotrófico glial que pode estar relacionado a estas alterações. Durante o período de fevereiro de 2007 a junho de 2008 foi realizado um estudo clínico prospectivo em cães com extrusão de disco intervertebral (n=10) submetidos à eletroacupuntura (grupo EA) sem o uso de corticosteróides. Foram coletadas amostras de líquido cefalorraquidiano (LCR) destes animais em dois momentos: durante o exame de mielografia e/ou tomografia computadorizada (M1) e após 35.5±21.33 dias de tratamento (M2). Níveis de S100&beta foram investigados no LCR de cães do grupo EA através da técnica de Western blot. LCR de cães sem sinais neurológicos (grupo normal, n=7) foram utilizados para comparação. Para a análise estatística, com nível de significância de 5%, foram utilizadas ANOVA para medidas repetidas e medidas independentes e comparação múltipla de Bonferroni, teste t-Student para a comparação entre duas médias e correlação linear de Pearson para as variáveis quantitativas. Todos os animais do grupo EA, graus de lesão 3 a 5, obtiveram melhora neurológica crescente e significativa (P-valor <0.001) através da Escala Funcional Numérica (EFN) nos M1 e M2 e M3 (momento da última avaliação). O grupo EA foi dividido em grupo A - cães com retorno à locomoção em até 30 dias (6.7±7.89; n=7) e grupo B - após 30 dias (76±17.06; n=3) do tratamento. Níveis de S100&beta; (Média±DP) em cães do grupo A foram superiores no M1 (P-valor=0.0107) em relação ao M2 e grupo normal, mas entre M2 e grupo normal não houve diferença significativa (P-valor=0.423). No entanto, níveis de S100&beta; em cães do grupo B foram superiores no M2 (P-valor=0.039) em relação ao M1 e normal, e não houve diferença significativa entre M1 e grupo normal (P-valor=0.756). Níveis de S100&beta; no M1 não diferiram (P-valor=0.069) entre os grupos A e B. Entretanto, níveis de S100&beta; no M2 em cães do grupo B foram superiores (P-valor=0.032) ao M2 em cães do grupo A. Não houve correlação dos níveis de S100&beta; no M1 com idade (r2=0.2042, P-valor=0.189); peso (r2=0.02634, P-valor=0.654), evolução clínica (r2=0.0062; P-valor=0.828), tempo de retorno à locomoção (r2=0.2522; P-valor=0.139) e extensão da extrusão (r2=0.0345; P-valor=0.607). Níveis de S100&beta; no M1 não apresentaram diferenças significativas entre os graus de lesão 3, 4 e 5 (P- valor=0.931); entre o grupo com escores de compressão extradural 1 e 2 comparado com grupo com escore de compressão 3 (P-valor=0.771); entre grupo de cães com EFN10 (P-valor=0.520) e entre grupo de cães com escores de nº de lesões 1, 2, 3 e 4 (P- valor=0.526). Níveis de S100&beta; no M2 não apresentaram diferenças significativas com a evolução clínica (r2=0.0304; Pvalor=0.629), extensão da extrusão (r2=0.0158; Pvalor=0.729), entretanto houve uma tendência a correlação com o tempo de retorno à locomoção (r2=0.3852; P-valor=0.055). A eletroacupuntura promoveu uma modulação dos níveis de S100&beta; detectados no LCR de cães com extrusão de disco intervertebral tóraco-lombar. A eletroacupuntura induziu aumento de S100&beta; no LCR de cães com recuperação motora tardia sugerindo sua contribuição na plasticidade neural após injúria da medula espinhal devido à extrusão de disco intervertebral. / Electroacupuncture treatment in dogs with thoracolumbar disk disease has the purpose of analgesia, motor and sensorial rehabilitation. The functional improvements observed after spinal cord lesion are resulting of synaptic plasticity. This fact is a result of compensatory mechanisms and not structural repair. S100&beta; is considered a glial neurotrophic factor. It can be involved with these improvements. A prospective clinical study during February 2007 to June 2008 evaluated electroacupuncture (EA) treatment (group EA) in dogs with thoracolumbar disk extrusion (n=10) without corticosteroids. Cerebrospinal fluids (CSF) were collected from these animals in two time points: during the mielography and/or computed tomography (M1) and after 35.5±21.33 (Mean±SD) days after EA treatment (M2). S100&beta; levels in CSF were investigated in dogs of group EA by Western blot. CSF of dogs without neurological signs (group normal; n=7) were used for comparisons. For the statistical analysis, significant level of 5%, ANOVA for repeated and not repeated variables (post-test Bonferroni´s), Student-t test for two variables comparisons and Pearsons linear correlation for quantitative variables, were used. All dogs (group EA) with lesion levels of dysfunction 3 to 5, reached neurological improvements with significant higher scores (P-value<0.001) from a functional numerical score (FNS) at each successive time points (M1; M2; M3 last evaluation). Group EA dogs were divided in group A - dogs with return of ambulation before 30 days (6.7±7.89; n=7) and group B - after 30 days (76±17.06; n=3). S100&beta; levels (Mean±SD) in group A dogs were higher in M1 (P-value=0.0107) than M2 and group normal, and there was not significant difference between M2 and group normal (P-value=0.423). Although, S100&beta; levels in group B dogs were higher in M2 (P-value=0.039) than M1 and group normal, and there was not significant difference between groups B M1 and normal (P-value=0.756). S100&beta; levels in M1 were not different (P-value=0.069) between dogs of group A and B. However, S100&beta; levels at M2 in group B dogs were significantly higher (P-value=0.032) than group A. The S100&beta; levels in M1 have no correlation with age (r2=0.2042; P-value=0.189); weight (r2=0.0263; P-value=0.654), duration of clinical signs (r2=0.0062; P-value=0.828), time of ambulation return (r2=0.2522; P-value=0.139) and extrusion length (r2=0.0345; P-value=0.607). There were no associations between S100&beta; levels at M1 and lesion levels of dysfunction 3, 4 e 5 (Pvalue=0.931); between extradural compression scores 1 and 2 compared with score 3 (Pvalue=0.771); between dogs with FNS10 (Pvalue=0.520) and between group of dogs with number of lesions scores 1, 2, 3 and 4 (Pvalue=0.5262). S100&beta; levels at M2 have no correlation with duration of clinical signs (r2=0.0304; Pvalue=0.629), extrusion length (r2=0.0158; P-value=0.729), however there was a tendency of correlation with time of ambulation return (r2=0.3852; Pvalue=0.055). Electroacupuncture can modulate the S100&beta; levels in CSF of dogs with thoracolumbar disk extrusion. Electroacupuncture up-regulated S100&beta; in CSF of dogs with late motor rehabilitation. This fact suggests its contribution in the neural plasticity after spinal cord lesion due to intervertebral disk extrusion.

T1rho弛豫是旋轉坐標系中的自旋晶格弛豫，它決定橫向磁化向量在存有自旋鎖定射頻脈衝情況下的衰減，自旋鎖定脈衝與橫向磁化向量同向。T1rho磁共振成像對於低頻運動過程敏感，故可研究水與其周大分子物質環境間的交互作用，有鑒別組織內早期生化改變的潛力。 / 衰老與慢性高血壓是常見腦退行性疾病的兩個主要危險因素。但是正常腦衰老過程及慢性高血壓兩個因素與腦組織T1rho是否有相關性，尚缺乏研究。序貫性測量SD老鼠自5至15月齡、WKY（血壓正常）和SHR（患有自發性高血壓）老鼠自6至12月齡的雙側丘腦、海馬、和皮質的腦組織T1rho值。發現三組老鼠的丘腦、海馬及皮質的T1rho均隨年齡增長而增高；且SHR的顯著高於WKY老鼠。 / T1rho值與椎間盤退變等級的相關性已有報導。但相比T2值，T1rho在評價椎間盤退變方面是否優於或如何優於T2值尚缺乏研究。將椎間盤髓核及纖維環的T1rho和T2值與5級和8級椎間盤退變等級系統做比較；發現髓核的T1rho及T2與椎間盤退變等級的相關性均呈二次函數降低，且無顯著差別(P=0.40)。纖維環的T1rho及T2與椎間盤退變等級的相關性呈線性函數降低，T2降低的斜率明顯比T1rho降低的斜率要平坦(P<0.001)。故T1rho值比T2值更加適合評價纖維環退變，而兩者在評價髓核時相似。 / 肝纖維化是幾乎所有慢性肝病的常見特徵，包括大分子物質在細胞外基質的沉積。選用四氯化碳CCl4腹腔注射6周來製造肝纖維化模型。肝臟T1rho在注射後的第二天輕度上升，然後持續上升，直到注射六周後T1rho達最高值，此後T1rho隨CCl4注射停止而降低。顯示T1rho磁共振成像對於監測慢性注射CCl4誘導的肝纖維化及肝損傷有價值。當沒有明顯肝纖維化時，肝T1rho輕微受水腫及急性炎症的影響。 / 為將肝臟T1rho磁共振成像轉化到臨床使用，我們研究了其可行性，以及正常志願者肝臟T1rho值分佈範圍。發現採用六個自旋鎖定時間來測量健康志願者肝T1rho，結果有較高的可重複性和一致性，肝T1rho平均值為42.5ms，分佈範圍為38.8到46.5ms。採用三個自鎖鎖定時間點掃描，可以減少一半掃描時間，且可以得到可信的肝T1rho值，但採用兩個自旋鎖定時間點則不行。 / T1rho relaxation is spin-lattice relaxation in the rotating frame. It determines the decay of the transverse magnetization in the presence of a spin-lock radiofrequency pulse, which applied along the transverse magnetization. T1rho MRI is sensitive to low frequency motional processes, so it can be used to investigate the interaction between water molecules and their macromolecular environment. T1rho imaging is suggested to have the potential to identify early biochemical changes in tissues. / Aging and chronic hypertension are two major risk factors for common neurodegenerative disease. However, whether normal brain aging and chronic spontaneous hypertensive are associated with brain T1rho values changes were not reported. We longitudinally measured the T1rho value in rat brain of Sprague-Dawley (SD) rats from 5-month to 15-month, and spontaneous hypertensive rats (SHR) with Wistar Kyoto (WKY) rats from 6-month to 12-month. The T1rho values in three brain regions of thalamus, hippocampus, and cortices increased with aging process, and were significantly higher in SHR than WKY rats. / For intervertebral disc, the correlation between T1rho and degenerative grade has been reported. However, whether and how T1rho specifically offer better evaluation of disc degeneration compared with T2 was not studied previously. T1rho and T2 value of nucleus pulposus (NP) and annulus fibrosus (AF) was compared with reference to the five-level and eight-level semi-quantitative disc degeneration grading systems. For NP, T1rho and T2 decreased quadratically with disc degeneration grades and had no significant trend difference (P=0.40). In NP, T1rho and T2 decrease in a similar pattern following disc degeneration. For AF, T1rho and T2 decreased linearly and the slopes of T2 were significantly flatter than those of T1rho (P<0.001). Therefore, the T1rho is better suited for evaluating AF in degenerated disc than T2. / Liver fibrosis, a common feature of almost all causes of chronic liver disease, involves macromolecules accumulated within the extracellular matrix. Male Sprague-Dawley rats received intraperitoneal injection of 2 ml/kg CCl4 twice weekly for up to 6 weeks. Then CCl4 was withdrawn for recovery. The liver T1rho values increased slightly on day 2, then increased further and were highest at week 6 post CCl4 insults, and decreased upon the withdrawal of the CCl4 insult. This study demonstrated that T1rho MRI is a valuable imaging biomarker for liver injury and fibrosis induced by CCl4. Liver T1rho value was only mildly affected by edema and acute inflammation when there was no apparent fibrosis. / To translate liver T1rho MRI to clinical application, the technical feasibility of T1rho MRI in human liver was explored and the normal range of T1rho values in healthy volunteers was determined. We found it is feasible to obtain consistent liver T1rho measurement for healthy human liver with six spin-lock time (SLT) points of 1, 10, 20, 30, 40, and 50ms; the mean liver T1rho value of the healthy subjects was 42.5ms, with a range of 38.8-46.5ms. Adopting 3-SLT points of 1, 20, and 50ms for T1rho measurement could provide reliable measurement and reduce the scanning time, while 2-SLT points of 1 and 50ms do not provide reliable measurement. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Zhao, Feng. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 119-143). / Abstracts also in Chinese. / ABSTRACT --- p.i / ACKNOWLEDGEMENTS --- p.vi / LIST OF FIGURES --- p.viii / LIST OF TABLES --- p.xvi / LIST OF ABBREVIATIONS --- p.xvii / CONTENTS --- p.xxi / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Conventional Magnetic Resonance Imaging --- p.1 / Chapter 1.1.1 --- Basic Principle of Conventional Magnetic Resonance Imaging --- p.1 / Chapter 1.1.2 --- T1 Relaxation --- p.2 / Chapter 1.1.3 --- T2 Relaxation --- p.3 / Chapter 1.2 --- T1rho Magnetic Resonance Imaging --- p.3 / Chapter 1.2.1 --- T1rho Relaxation --- p.3 / Chapter 1.2.2 --- Principle of T1rho Magnetic Resonance Imaging --- p.4 / Chapter 1.2.3 --- Radiofrequency Pulse for T1rho Magnetic Resonance Imaging --- p.5 / Chapter 1.2.4 --- T1rho-weighted Contrast Imaging and Application --- p.10 / Chapter 1.2.5 --- Quantitative T1rho Mapping and Application --- p.11 / Chapter 1.2.6 --- T1rho Dispersion and Application --- p.13 / Chapter 1.3 --- Thesis Overview --- p.14 / Chapter Chapter 2 --- T1rho MRI in brain aging of animal model --- p.19 / Chapter 2.1 --- Introduction --- p.19 / Chapter 2.2 --- Materials and Methods --- p.20 / Chapter 2.2.1 --- Animal Model of Brain Aging --- p.20 / Chapter 2.2.2 --- T1rho Data Acquisition --- p.21 / Chapter 2.2.3 --- T1rho Data Processing --- p.23 / Chapter 2.2.4 --- T1rho Measurement and Statistical Analysis --- p.24 / Chapter 2.3 --- Results --- p.27 / Chapter 2.4 --- Discussion --- p.38 / Chapter 2.5 --- Summary --- p.42 / Chapter Chapter 3 --- T1rho MRI in lumbar disc degeneration of human subjects --- p.43 / Chapter 3.1 --- Introduction --- p.43 / Chapter 3.2 --- Methods --- p.45 / Chapter 3.2.1 --- Subjects --- p.45 / Chapter 3.2.2 --- MR Image Acquisition --- p.46 / Chapter 3.2.2.1 --- T2-weighted MRI --- p.46 / Chapter 3.2.2.2 --- T2 Mapping Imaging --- p.47 / Chapter 3.2.2.3 --- T1rho MRI --- p.47 / Chapter 3.2.3 --- Data Processing --- p.49 / Chapter 3.2.4 --- Data Measurement and Statistical Analysis --- p.49 / Chapter 3.3 --- Results --- p.52 / Chapter 3.3.1 --- Range of T1rho/T2 Values for Discs --- p.52 / Chapter 3.3.2 --- The Relationship between NP T1rho/T2 Values and 8-level Degeneration Grading of Discs --- p.52 / Chapter 3.3.3 --- The Relationship between NP T1rho/T2 Values and 5-level Degeneration Grading of Discs --- p.55 / Chapter 3.3.4 --- The Relationship between AF T1rho/T2 Values and 8-level Degeneration Grading of Discs --- p.58 / Chapter 3.3.5 --- The Relationship between AF T1rho/T2 Values and 8-level Degeneration Grading of Discs --- p.61 / Chapter 3.4 --- Discussion --- p.64 / Chapter 3.5 --- Summary --- p.69 / Chapter Chapter 4 --- T1rho MRI in rat liver fibrosis model induced by CCl4 insult --- p.71 / Chapter 4.1 --- Introduction --- p.71 / Chapter 4.2 --- Materials and Methods --- p.73 / Chapter 4.2.1 --- Animal Preparation --- p.73 / Chapter 4.2.2 --- MR Image Acquisition --- p.74 / Chapter 4.2.2.1 --- T2-weighted MRI --- p.75 / Chapter 4.2.2.2 --- T1rho MRI --- p.75 / Chapter 4.2.3 --- Data Processing --- p.76 / Chapter 4.2.4 --- Data Measurement and Statistical Analysis --- p.78 / Chapter 4.2.5 --- Histology Analysis --- p.79 / Chapter 4.3 --- Results --- p.80 / Chapter 4.3.1 --- T1rho Measurement Reproducibility --- p.80 / Chapter 4.3.2 --- Rat Liver T1rho Values at Different Time Phase --- p.81 / Chapter 4.3.3 --- Relative Rat Liver Signal Intensity on T2WI at Different Time Phase --- p.83 / Chapter 4.3.4 --- Histology Results --- p.84 / Chapter 4.4 --- Discussion --- p.86 / Chapter 4.5 --- Summary --- p.91 / Chapter Chapter 5 --- T1rho MRI in liver of healthy human subjects --- p.93 / Chapter 5.1 --- Introduction --- p.93 / Chapter 5.2 --- Methods --- p.95 / Chapter 5.2.1 --- Subjects --- p.95 / Chapter 5.2.2 --- MR Image Acquisition --- p.96 / Chapter 5.2.2.1 --- T2-weighted MRI --- p.96 / Chapter 5.2.2.2 --- T1rho MRI --- p.97 / Chapter 5.2.3 --- T1rho Data Processing --- p.99 / Chapter 5.2.4 --- T1rho Measurement --- p.100 / Chapter 5.3 --- Results --- p.102 / Chapter 5.3.1 --- T1rho Measurement Reproducibility --- p.105 / Chapter 5.3.2 --- T1rho Value Agreement of the Fasting Status with Post Meal Status --- p.105 / Chapter 5.3.3 --- T1rho Value Agreement for T1rho Maps Constructed by Different Spin-lock Time Points --- p.106 / Chapter 5.3.4 --- T1rho Value Range of Healthy Human Subjects --- p.108 / Chapter 5.4 --- Discussion --- p.108 / Chapter 5.5 --- Summary --- p.113 / Chapter Chapter 6 --- General discussion and further work --- p.115 / References: --- p.119 / LIST OF PUBLICATIONS --- p.138