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1.
Aliment Pharmacol Ther ; 44(4): 411-21, 2016 08.
Artículo en Inglés | MEDLINE | ID: mdl-27301337

RESUMEN

BACKGROUND: Little is known about the importance of liver fibrosis and fatty liver in HIV-monoinfected individuals without hepatitis virus co-infection, particularly among the Asian population. AIM: To evaluate prevalence and risk factors for liver fibrosis and fatty liver in Asian HIV-monoinfected individuals. METHODS: Eighty asymptomatic HIV-monoinfected individuals (tested negative for HBV/HCV) were compared with 160 matched HIV-uninfected healthy controls. Transient elastography and proton-magnetic resonance spectroscopy ((1) H-MRS) were performed to measure liver stiffness and hepatic steatosis respectively. Blood samples were analysed for metabolic profiles and markers of steatohepatitis (e.g. cytokeratin-18). RESULTS: All HIV-infected individuals (mean ± s.d. age 54 ± 11 years, male 93%, Chinese 94%; diagnosis median duration 8 (IQR 4-13 years) were stable on anti-retrovirals (PI-based 58.7%, NNRTI-based 25.0% integrase-inhibitors 16.3%); diabetes, dyslipidaemia, and metabolic syndrome were common. Fatty liver disease was detected in 28.7%. There was significantly higher degree of liver stiffness [4.9 (IQR 4.1-6.2) kPa vs. 4.2 (IQR 3.6-5.0) kPa, P < 0.001], and greater proportions developed significant fibrosis (7.0 kPa, 14.3% vs. 3.1%, P = 0.001) and cirrhosis (10.3 kPa, 5.2% vs. 0.6%, P = 0.040) compared with controls. HIV infection was an independent risk factor for significant fibrosis (adjusted OR 4.00, 95% CI 1.29-12.41, P = 0.016). HIV-infected individuals with fatty liver had excessive liver stiffness and fibrosis. Two cases of asymptomatic hepatocellular carcinoma were detected. CONCLUSIONS: HIV-monoinfected patients are at risk for liver fibrosis and cirrhosis. HIV-related mechanisms and fatty liver disease may play important roles. Screening and intervention to prevent severe outcomes should be considered.


Asunto(s)
Hígado Graso/etiología , Infecciones por VIH/complicaciones , Cirrosis Hepática/etiología , Adulto , Anciano , Pueblo Asiatico , Biomarcadores/sangre , Carcinoma Hepatocelular/sangre , Carcinoma Hepatocelular/diagnóstico por imagen , Carcinoma Hepatocelular/etiología , Estudios de Casos y Controles , Diagnóstico por Imagen de Elasticidad , Hígado Graso/sangre , Hígado Graso/diagnóstico por imagen , Femenino , Infecciones por VIH/sangre , Infecciones por VIH/diagnóstico por imagen , Hong Kong/epidemiología , Humanos , Queratina-18/sangre , Cirrosis Hepática/sangre , Cirrosis Hepática/diagnóstico por imagen , Neoplasias Hepáticas/sangre , Neoplasias Hepáticas/diagnóstico por imagen , Neoplasias Hepáticas/etiología , Espectroscopía de Resonancia Magnética , Masculino , Persona de Mediana Edad , Prevalencia , Factores de Riesgo
2.
AJNR Am J Neuroradiol ; 37(9): 1706-12, 2016 09.
Artículo en Inglés | MEDLINE | ID: mdl-27151750

RESUMEN

BACKGROUND AND PURPOSE: Pretreatment prediction of patients with nasopharyngeal carcinoma who will fail conventional treatment would potentially allow these patients to undergo more intensive treatment or closer posttreatment monitoring. The aim of the study was to determine the ability of pretreatment DWI to predict local failure in patients with nasopharyngeal carcinoma based on long-term clinical outcome. MATERIALS AND METHODS: One hundred fifty-eight patients with pretreatment DWI underwent analysis of the primary tumor to obtain the ADC mean, ADC skewness, ADC kurtosis, volume, and T-stage. Univariate and multivariate analyses using logistic regression were performed to compare the ADC parameters, volume, T-stage, and patient age in primary tumors with local failure and those with local control, by using a minimum of 5-year follow-up to confirm local control. RESULTS: Local control was achieved in 131/158 (83%) patients (range, 60.3-117.7 months) and local failure occurred in 27/158 (17%) patients (range, 5.2-79.8 months). Compared with tumors with local control, those with local failure showed a significantly lower ADC skewness (ADC values with the greatest frequencies were shifted away from the lower ADC range) (P = .006) and lower ADC kurtosis (curve peak broader) (P = .024). The ADC skewness remained significant on multivariate analysis (P = .044). There was a trend toward higher tumor volumes in local failure, but the volume, together with T-stage and ADC mean, were not significantly different between the 2 groups. CONCLUSIONS: Pretreatment DWI of primary tumors found that the skewness of the ADC distribution curve was a predictor of local failure in patients with nasopharyngeal carcinoma, based on long-term clinical outcome.


Asunto(s)
Carcinoma/diagnóstico por imagen , Carcinoma/cirugía , Imagen de Difusión por Resonancia Magnética/métodos , Neoplasias Nasofaríngeas/diagnóstico por imagen , Neoplasias Nasofaríngeas/cirugía , Adulto , Factores de Edad , Anciano , Determinación de Punto Final , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Persona de Mediana Edad , Carcinoma Nasofaríngeo , Valor Predictivo de las Pruebas , Insuficiencia del Tratamiento , Resultado del Tratamiento
3.
Aliment Pharmacol Ther ; 42(6): 731-40, 2015 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-26202818

RESUMEN

BACKGROUND: Patients with non-alcoholic steatohepatitis (NASH) have increased intestinal permeability and small intestine bacterial overgrowth. AIMS: To test the hypothesis that endotoxemia is associated with non-alcoholic fatty liver disease (NAFLD) in the general population, and to study dietary factors associated with endotoxemia. METHODS: Nine hundred and twenty adults were randomly selected from the government's census database and underwent proton-magnetic resonance spectroscopy to assess hepatic steatosis. Endotoxemia was assessed using the limulus amebocyte lysate, lipopolysaccharide-binding protein (LBP) and EndoCab immunoglobulin G (IgG) assays. RESULTS: Two hundred and sixty-three (29%) subjects had NAFLD. Subjects with NAFLD had slightly higher LBP (P < 0.001) and EndoCab IgG (P = 0.013) levels. EndoCab IgG remained an independent factor associated with intrahepatic triglycerides after adjusting for other metabolic factors. Among 565 subjects without NAFLD at baseline who had repeated assessment at a median interval of 47 months, 78 (13.8%) developed incident NAFLD and they also had higher LBP (P = 0.016). Moreover, LBP was associated with insulin resistance and dyslipidaemia, and modestly increased with the cytokeratin-18 fragment level but not liver stiffness measurement by transient elastography. Although total energy consumption and individual macronutrients were not associated with endotoxemia, current drinkers (mostly <140 g/week) had lower endotoxin, EndoCab IgG and fetuin-A levels than nondrinkers. CONCLUSIONS: Endotoxin markers are associated with NAFLD in the general population, but do not have a major effect on NASH and fibrosis. People with modest alcohol consumption have lower serum endotoxin. This may partly explain the lower risk of NAFLD and NASH in modest drinkers in previous observational studies.


Asunto(s)
Dieta , Endotoxemia/epidemiología , Endotoxemia/fisiopatología , Enfermedad del Hígado Graso no Alcohólico/epidemiología , Enfermedad del Hígado Graso no Alcohólico/fisiopatología , Proteínas de Fase Aguda/metabolismo , Adulto , Consumo de Bebidas Alcohólicas/metabolismo , Biomarcadores , Proteínas Portadoras/metabolismo , Dislipidemias/metabolismo , Femenino , Fibrosis , Humanos , Inmunoglobulina G/metabolismo , Resistencia a la Insulina/fisiología , Intestinos/microbiología , Queratina-18/metabolismo , Masculino , Glicoproteínas de Membrana/metabolismo , Persona de Mediana Edad , Datos de Secuencia Molecular , Estudios Prospectivos
4.
Aliment Pharmacol Ther ; 39(5): 532-9, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24417250

RESUMEN

BACKGROUND: The rs738409 GG variant in patatin-like phospholipase 3 (PNPLA3) is associated with non-alcoholic fatty liver disease (NAFLD) and disease severity. However, it remains unclear if it contributes to the development of NAFLD through affecting dietary pattern. AIM: To examine the association among PNPLA3 gene polymorphism, dietary pattern, metabolic factors and NAFLD. METHODS: Liver fat and fibrosis were assessed by proton-magnetic resonance spectroscopy and transient elastography in 920 subjects from a population screening project (251 had NAFLD). Dietary nutrient intake was recorded using a locally validated food-frequency questionnaire. RESULTS: The prevalence of GG genotype in NAFLD subjects was 20.7%, compared to 10.6% in controls (P < 0.001). Macronutrient intake was similar among subjects with different PNPLA3 genotypes. The presence of G allele was a predictor of NAFLD independent of nutrient intake and other metabolic factors (adjusted odds ratio to CC: CG, 2.00; GG, 2.68). In subjects without metabolic syndrome, G allele was even more closely correlated with NAFLD diagnosis (adjusted odds ratio to CC: CG, 2.22; GG, 3.39). The prevalence of NAFLD was only 12% in subjects with CC genotype and no metabolic syndrome, and increased to 34% in those with GG genotype and no metabolic syndrome. While NAFLD subjects had significantly lower fibre intake, there was no significant interaction between PNPLA3 and dietary pattern. CONCLUSIONS: The G allele in PNPLA3 rs738409 increases the risk of NAFLD in the general population, especially in subjects without metabolic syndrome, independent of dietary pattern and metabolic factors.


Asunto(s)
Hígado Graso/genética , Lipasa/genética , Proteínas de la Membrana/genética , Adulto , Dieta , Femenino , Humanos , Masculino , Síndrome Metabólico , Persona de Mediana Edad , Enfermedad del Hígado Graso no Alcohólico , Polimorfismo Genético
5.
Br J Neurosurg ; 27(5): 662-7, 2013 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-23458559

RESUMEN

PURPOSE: This study investigated the volumetric relationship of white matter lesion (WML) and contrast-enhanced lesion (CEL) in delayed radiation brain injury (RBI) during the course of evolution. MATERIALS AND METHODS: MRI results in 45 patients with RBI after receiving radiation for nasopharyngeal carcinoma were analyzed. In total there were 75 lobes with RBI and 114 MRI examinations in this study. WML and CEL lesion volumes were measured. The lesion volume change of less than 5% or 0.25 cm(3) was regarded as being static. RESULTS: The average WML volume was 16.33 cm(3) (ranging 0.11 cm(3) to 102.83 cm(3)), and the average CEL volume was 3.15 cm(3) (ranging 0.03 cm(3) to 27.85 cm(3)). WML was larger than CEL in 164 measurements, and CEL was larger than WML in 10 measurements. In 64.3% follow-ups WML and CEL evolved in the same pattern; and in most follow-ups (93.8%) WML and CEL did not evolve in the opposite directions. A larger WML volume tended to have a larger CEL volume though this relationship was not linear. CONCLUSION: Evolution of WML and CEL tended to follow the same pattern. WML tended to be larger than CEL, and larger WML tended to be associated with larger CEL.


Asunto(s)
Encéfalo/efectos de la radiación , Leucoencefalopatías/patología , Traumatismos por Radiación/patología , Adulto , Anciano , Medios de Contraste , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Neoplasias Nasofaríngeas/radioterapia , Estudios Retrospectivos
6.
AJNR Am J Neuroradiol ; 34(6): 1237-41, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23306012

RESUMEN

BACKGROUND AND PURPOSE: T2-weighted MRI shows potential in early posttreatment assessment of the primary tumor. Residual masses composed entirely of low T2-signal scar tissue suggest local control and those ≥1 cm of similar signal to untreated tumor suggest local failure. The purpose of this study was to investigate the diagnostic accuracy of T2-weighted MR imaging early after chemoradiotherapy for identifying primary tumor treatment failure in squamous cell carcinoma of the head and neck. MATERIALS AND METHODS: At 6 weeks after treatment, T2-weighted MR images of 37 primary tumors in 37 patients were assessed. Residual masses were divided into 3 patterns: pattern 1 = scar tissue only (flat-edged/retracted mass of low T2 signal intensity); pattern 2 = mass without features described in pattern 1 or 3; and pattern 3 = any pattern that included an expansile mass ≥1 cm of intermediate T2 signal intensity (similar grade of signal intensity to the untreated tumor). T2 patterns were analyzed for local outcome (Fisher exact test) and time to local failure (univariate and multivariate analysis of T2 pattern, age, T stage, and tumor size by use of the Cox regression model). RESULTS: Residual masses after treatment were present in 34 (92%) of 37 patients. Local failures occurred in residual masses with pattern 1 in 0 (0%) of 14 patients; pattern 2 in 6 (55%) of 11 patients; and pattern 3 in 9 (100%) of 9 patients. Significant associations were found between local control and pattern 1 (P = <.0001; sensitivity, 74%; specificity, 100%; PPV, 100%; NPV, 75%; accuracy, 85%), and between local failure and pattern 3 (P = <.0001; sensitivity, 60%; specificity, 100%; PPV, 100%; NPV, 76%; accuracy, 82%). Pattern 2 showed no significant associations with local outcome. Univariate analysis of time to local failure showed that the T2 pattern was significant (P < .0001) and remained significant on multivariate analysis. CONCLUSIONS: T2-weighted MR imaging is a potential tool for early posttreatment assessment of primary HNSCC treatment response. Awareness of correlation of the T2 pattern of any residual mass with treatment outcome at the primary site may contribute to patient treatment.


Asunto(s)
Carcinoma de Células Escamosas/patología , Carcinoma de Células Escamosas/terapia , Quimioradioterapia , Imagen de Difusión por Resonancia Magnética/métodos , Neoplasias de Cabeza y Cuello/patología , Neoplasias de Cabeza y Cuello/terapia , Anciano , Imagen de Difusión por Resonancia Magnética/normas , Monitoreo de Drogas/métodos , Femenino , Humanos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Neoplasia Residual/patología , Neoplasia Residual/terapia , Valor Predictivo de las Pruebas , Reproducibilidad de los Resultados , Estudios Retrospectivos , Sensibilidad y Especificidad , Insuficiencia del Tratamiento
7.
Aliment Pharmacol Ther ; 36(11-12): 1057-66, 2012 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-23066946

RESUMEN

BACKGROUND: The diagnosis of non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH) and fibrosis relies on liver biopsy. Non-invasive assessments are urgently needed. AIM: To evaluate cell apoptotic marker cytokeratin-18 M30 and total cell death markers cytokeratin-18 M65/M65ED for the assessment and monitoring of NAFLD. METHODS: A cohort of 147 patients with biopsy-proven NAFLD and 73 controls were enrolled, including 51 patients who received paired liver biopsies 36 months apart. Biomarkers were determined by enzyme-linked immunosorbent assay. RESULTS: M30, M65 and M65ED increased in a stepwise fashion in control subjects, patients with non-NASH, NAFLD and NASH (all P < 0.001). All biomarkers had similarly high accuracy over 0.9 in predicting NAFLD and moderate accuracy around 0.7 in predicting NASH. Among patients with paired liver biopsies, changes in M30, M65 and M65ED positively correlated with disease progression (rho = 0.42, 0.32 and 0.39; P = 0.002, 0.023 and 0.005 respectively), and only changes in M65 and M65ED correlated with fibrosis progression (rho = 0.29, 0.34; P = 0.038, 0.015 respectively). Both M30 and M65 had area under receiver-operating characteristics curve above 0.8 in predicting disease progression. At cut-off of 236 U/L, changes of M65ED had 88% NPV and 59% PPV to exclude and predict fibrosis progression. CONCLUSIONS: Cytokeratin-18 M30 and M65/M65ED have moderate accuracy in detecting non-alcoholic steatohepatitis. Changes in the biomarkers also correlate with histological progression. However, development of new biomarkers is still required to improve the diagnostic accuracy.


Asunto(s)
Biomarcadores/sangre , Hígado Graso/sangre , Queratina-18/sangre , Fragmentos de Péptidos/sangre , Adulto , Apoptosis , Estudios de Casos y Controles , Muerte Celular , Progresión de la Enfermedad , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Enfermedad del Hígado Graso no Alcohólico , Valor Predictivo de las Pruebas
8.
Clin Radiol ; 67(3): 216-23, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-21939962

RESUMEN

AIM: To devise a method to convert the time-intensity curves (TICs) of head and neck dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) data into a pixel-by-pixel colour-coded map for identifying normal tissues and tumours. MATERIALS AND METHODS: Twenty-three patients with head and neck squamous cell carcinoma (HNSCC) underwent DCE-MRI. TIC patterns of primary tumours, metastatic nodes, and normal tissues were assessed and a program was devised to convert the patterns into a classified colour-coded map. The enhancement patterns of tumours and normal tissue structures were evaluated and categorized into nine grades (0-8) based on the predominance of coloured pixels on maps. RESULTS: Five identified TIC patterns were converted into a colour-coded map consisting of red (maximum enhancement), brown (continuous slow rise-up), yellow (rapid wash-in and wash-out), green (rapid wash-in and plateau), and blue (rapid wash-in and rise-up). The colour-coded map distinguished all 21 primary tumours and 15 metastatic nodes from normal structures. Primary tumours and metastatic nodes were colour coded as predominantly yellow (grades 1-2) in 17/21 and 6/15, green (grades 3-5) in 3/21 and 5/15, and blue (grades 6-7) in 1/21 and 4/15, respectively. Vessels were coded red in 46/46 (grade 0) and muscles were coded brown in 23/23 (grade 8). Salivary glands, thyroid glands, and palatine tonsils were coded into predominantly yellow (grade 1) in 46/46 and 10/10 and 18/22, respectively. CONCLUSION: DCE-MRI derived five-colour-coded mapping provides an objective easy-to-interpret method to assess the dynamic enhancement pattern of head and neck cancers.


Asunto(s)
Carcinoma de Células Escamosas/diagnóstico , Neoplasias de Cabeza y Cuello/diagnóstico , Interpretación de Imagen Asistida por Computador/métodos , Imagen por Resonancia Magnética/métodos , Algoritmos , Color , Medios de Contraste , Gadolinio DTPA , Humanos
9.
Osteoporos Int ; 22(1): 91-6, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-20352410

RESUMEN

UNLABELLED: The study cohort comprised 196 females and 163 males. Lumbar spine bone mineral density (BMD) and magnetic resonance imaging (MRI) were acquired. Females had more severe disc degeneration than males. Lumbar spine lower BMD was associated with less severe disc degeneration. Lumbar disc spaces were more likely to be narrower when vertebral BMD was higher. INTRODUCTION: The purpose of this paper is to study the relationship between gender, BMD, and disc degeneration in the lumbar spine. METHODS: The study cohort comprised 196 females and 163 males (age range 67-89 years) with no age difference between the two groups. Lumbar spine BMD was measured with dual X-ray densitometry, and MRI was acquired at 1.5 T. A subgroup of 48 males had additional lumbar vertebral quantitative computerized tomography densitometry. Lumbar disc degeneration was assessed using a MRI-based eight-level grading system. RESULTS: Female subjects had more severe disc degeneration than male subjects. After removing age effect, a positive trend was observed between T-score and severity of lumbar disc degeneration. This was significant in female subjects while not significant in male subjects. Lumbar disc spaces were more likely to be narrowed when vertebral BMD was higher. These observations were more significant in the midlumbar region (L3/4 and L4/5) and less so at the thoracolumbar junction. CONCLUSION: Female subjects tended to have slightly more severe lumbar disc degeneration than male subjects. Lower lumbar spine BMD was associated with less severe disc degeneration.


Asunto(s)
Densidad Ósea/fisiología , Degeneración del Disco Intervertebral/fisiopatología , Vértebras Lumbares/fisiopatología , Anciano , Anciano de 80 o más Años , Enfermedades Óseas Metabólicas/complicaciones , Enfermedades Óseas Metabólicas/fisiopatología , Estudios de Cohortes , Femenino , Humanos , Degeneración del Disco Intervertebral/complicaciones , Degeneración del Disco Intervertebral/patología , Imagen por Resonancia Magnética/métodos , Masculino , Osteoporosis/complicaciones , Osteoporosis/fisiopatología , Índice de Severidad de la Enfermedad , Factores Sexuales
10.
Br J Radiol ; 83(993): 753-8, 2010 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-20647507

RESUMEN

The utility of diffusion-weighted imaging (DWI) in the detection of squamous cell carcinoma (SCC) of the tonsils has not been previously investigated. This preliminary study compared DWI of apparent SCC tonsillar tumours with normal tonsils. DWI of the tonsils was performed in 10 patients with newly diagnosed tonsil SCC that was evident on conventional MRI and in 17 patients undergoing cranial MRI for other indications. Regions of interest (ROI) were drawn around each identifiable tonsil on the apparent diffusion coefficient (ADC) map and the mean ADC value for each tonsil was calculated. ADC values for normal and SCC tonsils were compared using the Mann-Whitney U-test. The median ADC and range (x10(-3) mm(2) s(-1)) were found to be 0.814 and 0.548-1.312, respectively, for normal tonsils compared with 0.933 and 0.789-1.175, respectively, for SCC tonsils. ADC values were significantly higher for SCC tonsils than for normal tonsils (p = 0.009). No SCC tonsil had an ADC less than 0.82 x 10(-3) mm(2) s(-1) compared with 58% of normal tonsils. We conclude that there is a difference in the ADC between normal tonsils and SCC tonsils where the cancer is apparent on conventional MRI. These results are promising, although further studies are now required to determine whether DWI can be used to identify or exclude smaller foci of SCC within tonsils where the cancer is not evident on conventional MRI.


Asunto(s)
Carcinoma de Células Escamosas/diagnóstico , Imagen de Difusión por Resonancia Magnética/métodos , Tonsila Palatina , Neoplasias Tonsilares/diagnóstico , Adulto , Femenino , Humanos , Masculino , Estudios Prospectivos , Reproducibilidad de los Resultados
11.
Bone ; 44(3): 495-501, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19059505

RESUMEN

Quantitative examination of iliac crest bone biopsies shows that as subjects become older bone and functional marrow are replaced by adipose tissue. Studies of vertebral marrow fat using nuclear magnetic resonance spectroscopy ((1)H-MRS) show that subjects with lower spine T-scores have significantly higher marrow fat content. These findings suggest that the ability of DXA scans to determine fracture risk may be partly explained by the effect of increased marrow fat on BMD. However, a proper evaluation of the relationship between WHO spine T-score status and marrow fat content requires that the BMD data are first corrected for the bias caused by a selection effect in which subjects with higher marrow fat are more likely to be identified as having osteoporosis. In this study we have therefore reanalysed previously published data for 185 elderly Hong Kong Chinese subjects (103 women, mean age 73 y; 82 men, mean age 73 y) who had spine DXA scans and (1)H-MRS measurements of L3 marrow fat. The effect of varying marrow fat on BMD was modelled using vertebral body thicknesses measured in 50 men and women. Spine T-scores in each individual were adjusted for the measured marrow fat. Subjects were assigned to WHO categories based on their corrected T-scores, and the relationship between marrow fat and T-score status evaluated using regression analysis and analysis of variance. The average change in percent marrow fat per T-score unit was used to infer the fraction of the spine BMD fracture discrimination explained by marrow composition. The mean (SD) of the L1-L4 vertebral body thickness was 30.2 (2.1) mm for Hong Kong women and 33.4 (2.5) mm for men. A change in marrow fat content from 0 to 100% was estimated to produce a BMD decrease of 0.14 g/cm(2) (1.3 T-score units) in women and 0.16 g/cm(2) (1.3 T-score units) in men. Although adjusting spine BMD for marrow fat reduced the significance of the correlation, there was still a trend for marrow fat to increase with decreasing T-score with a slope of -1.2+/-0.7% per T-score unit (p=0.078) for women and -1.4+/-0.6% per T-score unit (p=0.023) for men. When the effect of marrow composition on fracture discrimination was evaluated the results showed that the higher vertebral marrow fat content found in osteoporotic subjects made a negligible contribution to the ability of spine BMD measurements to predict fracture risk.


Asunto(s)
Absorciometría de Fotón , Densidad Ósea , Médula Ósea/anatomía & histología , Vértebras Lumbares , Fracturas de la Columna Vertebral , Anciano , Femenino , Humanos , Vértebras Lumbares/anatomía & histología , Vértebras Lumbares/patología , Masculino , Factores de Riesgo
12.
Phys Med Biol ; 54(1): 149-60, 2009 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-19075357

RESUMEN

Terahertz pulsed imaging (TPI) is a non-ionizing and non-destructive imaging technique that has been recently used to study a wide range of biological materials. The severe attenuation of terahertz radiation in samples with high water content means that biological samples need to be very thin if they are to be measured in transmission geometry. To overcome this limitation, samples could be measured in reflection geometry and this is the most feasible way in which TPI could be performed in a clinical setting. In this study, we therefore used TPI in reflection geometry to characterize the terahertz properties of several organ samples freshly harvested from laboratory rats. We observed differences in the measured time domain responses and determined the frequency-dependent optical properties to characterize the samples further. We found statistically significant differences between the tissue types. These results show that TPI has the potential to accurately differentiate between tissue types non-invasively.


Asunto(s)
Especificidad de Órganos , Imágen por Terahertz/instrumentación , Absorción , Animales , Femenino , Ratas , Ratas Sprague-Dawley , Factores de Tiempo
13.
Acta Neurochir Suppl ; 95: 173-5, 2005.
Artículo en Inglés | MEDLINE | ID: mdl-16463845

RESUMEN

The objective of the study was to evaluate radiation-induced cerebral injury on dynamic susceptibility contrast-enhanced (DSCE) perfusion MR imaging and study its relationship with morphological severity and disease progression. Thirty-one patients with known radiation injury to the temporal lobes where studied. Gradient and spin-echo T2-weighted, gadolinium-enhanced T1-weighted and DSCE perfusion MR imaging were obtained in the coronal plane through the anterior temporal lobe. Regions of interest where selected in the anterior temporal lobes and the superior frontal lobe as control for analysis of perfusion parameters. The mean transit time (MTT) was prolonged in both the High Dose Zone (HDZ) receiving from two-thirds to the total dose of 66-71.2 Gy, and the Intermediary Dose Zone (IDZ) receiving up to 87% of the total dose. The HDZ but not the IDZ showed a low relative cerebral blood volume (rCBV) and relative cerebral blood flow index (rCBFi). The rCBV and rCBFi were significantly lower in both HDZ and LBZ in temporal lobes with severe lesions compared to the temporal lobes with mild lesions but there was no significant difference in bolus transit parameters. The rCBV and rCBFi were significantly lower in both HDZ and IDZ of the swollen temporal lobes compared to those without swelling. It was concluded that DSCE perfusion MR imaging demonstrated a derangement in perfusion in radiation-induced cerebral injury in rCBV, rCBFi and MTT, which were related to the severity of the radiation-induced injury and the dose of irradiation delivered.


Asunto(s)
Lesiones Encefálicas/patología , Encéfalo/irrigación sanguínea , Circulación Cerebrovascular , Compuestos Heterocíclicos , Aumento de la Imagen/métodos , Imagen por Resonancia Magnética/métodos , Compuestos Organometálicos , Traumatismos por Radiación/patología , Adulto , Anciano , Lesiones Encefálicas/etiología , Medios de Contraste , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neoplasias Nasofaríngeas/radioterapia , Dosis de Radiación , Traumatismos por Radiación/etiología , Radioterapia/efectos adversos , Lóbulo Temporal/irrigación sanguínea , Lóbulo Temporal/lesiones , Lóbulo Temporal/patología , Lóbulo Temporal/efectos de la radiación
15.
AJNR Am J Neuroradiol ; 23(9): 1557-60, 2002 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-12372747

RESUMEN

We herein describe the case of a patient with chronic renal failure complicated by star fruit poisoning. T2-weighted and diffusion-weighted MR imaging showed hyperintense lesions at the thalami and right temporo-occipital cortex. Single voxel proton MR spectroscopy revealed elevation of lactate and (31)phosphorous MR spectroscopy revealed elevation of inorganic phosphate and decrease of phosphocreatine and nucleoside triphosphates. The imaging and metabolic changes indicated energy deprivation, with subsequent cortical necrosis proved at autopsy.


Asunto(s)
Ácido Aspártico/análogos & derivados , Química Encefálica , Encéfalo/patología , Imagen de Difusión por Resonancia Magnética , Frutas/envenenamiento , Espectroscopía de Resonancia Magnética , Ácido Aspártico/análisis , Humanos , Fallo Renal Crónico/metabolismo , Fallo Renal Crónico/terapia , Ácido Láctico/análisis , Masculino , Persona de Mediana Edad , Nucleótidos/análisis , Fosfatos/análisis , Fosfocreatina/análisis , Diálisis Renal
16.
Gut ; 50(1): 118-22, 2002 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11772978

RESUMEN

BACKGROUND: Biliary obstruction impairs liver function although the pathophysiological mechanism is incompletely understood. AIMS: The aim of this study was to examine serial changes in liver metabolism in patients with obstructive jaundice using image guided in vivo 31-phosphorus magnetic resonance spectroscopy ((31)P MRS). This technique allows repeated and non-invasive assay of organ energy metabolism and phospholipid biochemistry. PATIENTS: We studied 10 patients presenting with obstructive jaundice secondary to extrahepatic localised malignancy. There were eight men and two women, median age 72 years (range 54-94), six with cholangiocarcinoma (all Bismuth type 1) and four with carcinoma of the head of the pancreas. Ten healthy volunteers (median age 24 years (range 21-26)) were studied for comparison. METHODS: Hepatic metabolism in jaundiced patients was measured by (31)P MRS at presentation and again after a one week period of biliary drainage. Conventional liver function tests were also recorded. RESULTS: Compared with controls, liver spectra from jaundiced patients contained an excess of phosphomonoester (PME) metabolites (PME/total phosphate median 10.3% (interquartile range 8.7-11.5) in controls, 15.4% (13.1-17.7) in jaundiced cases; p<0.01). Biliary decompression was achieved in all patients (five with internal stents and five by external drainage catheters), and plasma biochemistry improved predictably (bilirubin 176 micromol/l (158-351) at presentation, 110 micromol/l (42-241) after drainage for one week; p<0.01). Enhancement of hepatic energy status, measured by the ratio of adenosine triphosphate (ATP) to inorganic phosphate (Pi), was observed in all cases after relief of biliary obstruction (ATP/Pi 1.4 (1.17-1.69) at presentation, 1.97 (1.4-2.48) after drainage; p<0.01) and was independent of the route of bile drainage. Hepatic phosphodiester (PDE) content was decreased after relief of obstruction (PDE/total phosphate 25.2% (20.5-27.4) at presentation, 19.8% (16.6-24.5) after drainage; p<0.01). This change was probably due to a reduction in the contribution from bile contents to this resonance as a strong PDE signal was also detectable in spectra obtained from separate bile specimens. CONCLUSIONS: Obstructive jaundice produces alterations in liver phosphoester biochemistry, most likely reflecting disturbances in phospholipid metabolism. Relief of biliary obstruction is associated with a measurable increase in hepatic energy status. Bile may contribute to the phosphodiester signal of the 31-phosphorus liver spectrum and changes in these resonances must therefore be interpreted with caution and in relation to the clinical situation. Monitoring of liver metabolism by (31)P MRS may allow clinicians to refine the selection and timing of therapeutic options in jaundiced patients.


Asunto(s)
Colestasis/metabolismo , Drenaje/métodos , Metabolismo Energético , Hígado/metabolismo , Espectroscopía de Resonancia Magnética/métodos , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Colestasis/diagnóstico , Colestasis/cirugía , Femenino , Humanos , Pruebas de Función Hepática , Masculino , Persona de Mediana Edad , Estadísticas no Paramétricas
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