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1.
Skeletal Radiol ; 51(4): 819-827, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34436624

RESUMO

OBJECTIVE: To evaluate magnetic resonance imaging (MRI) characteristics of simple and aneurysmal bone cysts (SBC/ABC) of the proximal humerus and the intermittent difficulty in the imaging differentiation between the two in daily clinical routine. MATERIALS AND METHODS: MR images of 26 patients with suspected SBC/ABC in the proximal humerus were retrospectively assessed by two independent radiologists blinded to the final histological result. Based on a standard MRI protocol, different morphologic features and signal intensities of the lesion on non-enhanced and enhanced sequences were documented. The radiological diagnosis was correlated with histology. RESULTS: Eighteen patients had the image-based diagnosis of an SBC, yet the histology confirmed only 12, the residual 6 were identified as an ABC, despite the imaging criteria corresponding unambiguously to the former. One of the main reasons was the unicameral morphology of lesions, found in 9/14 (64.3%) cases of all ABCs, i.e., in 19/26 cases in total. Therefore, the sensitivity of the radiological diagnosis was moderate (57.14%), yet specificity very high (100%). In total, 69.2% (18/26) presented with a pathological fracture at admission, which correlated strongly with both circumferential (MCC = 0.65, p = 0.01) and septal (MCC = 0.42, p = 0.06) enhancement patterns. Circumferential enhancement was also found to correlate strongly with the histological diagnosis, being recognized in all cases of ABC (MCC = 0.44, p = 0.06). CONCLUSION: MRI characteristics of ABCs/SBCs in the proximal humerus are indifferent and ABCs may morphologically present as SBCs. Radiologists should be aware of the different, often confusing presentation of both entities in daily clinical routine.


Assuntos
Cistos Ósseos Aneurismáticos , Cistos Ósseos , Cistos Ósseos/patologia , Cistos Ósseos Aneurismáticos/diagnóstico por imagem , Cistos Ósseos Aneurismáticos/patologia , Epífises/patologia , Humanos , Úmero/diagnóstico por imagem , Imageamento por Ressonância Magnética , Estudos Retrospectivos
2.
Histochem Cell Biol ; 155(1): 19-73, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33040183

RESUMO

This multidisciplinary study examined the pharmacokinetics of nanoparticles based on albumin-DTPA-gadolinium chelates, testing the hypothesis that these nanoparticles create a stronger vessel signal than conventional gadolinium-based contrast agents and exploring if they are safe for clinical use. Nanoparticles based on human serum albumin, bearing gadolinium and designed for use in magnetic resonance imaging, were used to generate magnet resonance images (MRI) of the vascular system in rats ("blood pool imaging"). At the low nanoparticle doses used for radionuclide imaging, nanoparticle-associated metals were cleared from the blood into the liver during the first 4 h after nanoparticle application. At the higher doses required for MRI, the liver became saturated and kidney and spleen acted as additional sinks for the metals, and accounted for most processing of the nanoparticles. The multiple components of the nanoparticles were cleared independently of one another. Albumin was detected in liver, spleen, and kidneys for up to 2 days after intravenous injection. Gadolinium was retained in the liver, kidneys, and spleen in significant concentrations for much longer. Gadolinium was present as significant fractions of initial dose for longer than 2 weeks after application, and gadolinium clearance was only complete after 6 weeks. Our analysis could not account quantitatively for the full dose of gadolinium that was applied, but numerous organs were found to contain gadolinium in the collagen of their connective tissues. Multiple lines of evidence indicated intracellular processing opening the DTPA chelates and leading to gadolinium long-term storage, in particular inside lysosomes. Turnover of the stored gadolinium was found to occur in soluble form in the kidneys, the liver, and the colon for up to 3 weeks after application. Gadolinium overload poses a significant hazard due to the high toxicity of free gadolinium ions. We discuss the relevance of our findings to gadolinium-deposition diseases.


Assuntos
Albuminas/farmacocinética , Quelantes/farmacocinética , Meios de Contraste/farmacocinética , Gadolínio DTPA/farmacocinética , Imageamento por Ressonância Magnética , Nanopartículas/química , Albuminas/administração & dosagem , Animais , Quelantes/administração & dosagem , Meios de Contraste/administração & dosagem , Feminino , Gadolínio DTPA/administração & dosagem , Injeções Intravenosas , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Nanopartículas/administração & dosagem , Ratos , Ratos Sprague-Dawley , Distribuição Tecidual
3.
Eur Radiol ; 30(11): 5826-5833, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32535737

RESUMO

OBJECTIVES: To assess clinically relevant difference in hepatic iron quantification using R2* relaxometry with (FS) and without (non-FS) fat saturation for the evaluation of patients with suspected hepatic iron overload. METHODS: We prospectively enrolled 134 patients who underwent 1.5-T MRI R2* relaxometry with FS and non-FS gradient echo sequences (12 echoes, initial TE = 0.99 ms). Proton density fat fraction for the quantification of steatosis was assessed. Linear regression analyses and Bland-Altman plots including Lin's concordance correlation coefficient were performed for correlation of FS R2* with non-FS R2*. Patients were grouped into 4 severity classes of iron overload (EASL based), and agreement was evaluated by contingency tables and the proportion of overall agreement. RESULTS: A total of 41.8% of patients showed hepatic iron overload; 67.9% had concomitant steatosis; and 58.2% revealed no iron overload of whom 60.3% had steatosis. The mean R2* value for all FS data was 102.86 1/s, for non-FS 108.16 1/s. Linear regression resulted in an R-squared value of 0.99 (p < 0.001); Bland-Altman plot showed a mean R2* difference of 5.26 1/s (SD 17.82). The concordance correlation coefficient was only slightly lower for patients with steatosis compared with non-steatosis (0.988 vs. 0.993). The overall agreement between FS and non-FS R2* measurements was 94.8% using either method to classify patients according to severity of iron storage. No correlation between R2* and proton density fat fraction was found for both methods. CONCLUSION: R2* relaxometry showed an excellent overall agreement between FS and non-FS acquisition. Both variants can therefore be used in daily routine. However, clinically relevant differences might result when switching between the two methods or during patient follow-up, when fat content changes over time. We therefore recommend choosing a method and keeping it straight in the context of follow-up examinations. KEY POINTS: • Both variants of R2* relaxometry (FS and non-FS) may be used in daily routine. • Clinically relevant differences might result when switching between the two methods or during patient follow-up, when fat content changes over time. • It seems advisable choosing one method and keeping it straight in the context of follow-up examinations.


Assuntos
Fígado Gorduroso/diagnóstico , Sobrecarga de Ferro/diagnóstico , Ferro/metabolismo , Fígado/metabolismo , Imageamento por Ressonância Magnética/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Fígado Gorduroso/etiologia , Fígado Gorduroso/metabolismo , Feminino , Humanos , Sobrecarga de Ferro/complicações , Sobrecarga de Ferro/metabolismo , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Adulto Jovem
4.
Eur Radiol ; 29(2): 829-837, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30027410

RESUMO

OBJECTIVES: To assess if the administration of gadoxetate disodium (Gd-EOB-DTPA) significantly affects hepatic magnetic resonance elastography (MRE) measurements in the delayed hepatobiliary phase (DHBP). METHODS: A total of 47 patients (15 females, 32 males; age range 23-78 years, mean 54.28 years) were assigned to standard hepatic magnetic resonance imaging (MRI) with application of Gd-EOB-DTPA and hepatic MRE. MRE was performed before injection of Gd-EOB-DTPA and after 40-50 min in the DHBP. Liver stiffness values were obtained before and after contrast media application and differences between pre- and post-Gd-EOB-DTPA values were evaluated using a Bland-Altman plot and the Mann-Whitney-Wilcoxon test. In addition, the data were compared with regard to the resulting fibrosis classification. RESULTS: Mean hepatic stiffness for pre-Gd-EOB-DTPA measurements was 4.01 kPa and post-Gd-EOB-DTPA measurements yielded 3.95 kPa. We found a highly significant individual correlation between pre- and post-Gd-EOB-DTPA stiffness values (Pearson correlation coefficient of r = 0.95 (p < 0.001) with no significant difference between the two measurements (p =0.49)). Bland-Altman plot did not show a systematic effect for the difference between pre- and post-stiffness measurements (mean difference: 0.06 kPa, SD 0.81). Regarding the classification of fibrosis stages, the overall agreement was 87.23% and the intraclass correlation coefficient was 96.4%, indicating excellent agreement. CONCLUSIONS: Administration of Gd-EOB-DTPA does not significantly influence MRE stiffness measurements of the liver in the DHBP. Therefore, MRE can be performed in the DHBP. KEY POINTS: • MRE of the liver can reliably be performed in the delayed hepatobiliary phase. • Gd-EOB-DTPA does not significantly influence MRE stiffness measurements of the liver. • MRE performed in the delayed hepatobiliary-phase is reasonable in patients with reduced liver function.


Assuntos
Meios de Contraste , Técnicas de Imagem por Elasticidade/métodos , Gadolínio DTPA , Hepatopatias/diagnóstico por imagem , Fígado/diagnóstico por imagem , Adulto , Idoso , Meios de Contraste/administração & dosagem , Feminino , Humanos , Fígado/patologia , Cirrose Hepática/diagnóstico por imagem , Hepatopatias/patologia , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Adulto Jovem
5.
Eur Radiol ; 28(3): 1111-1117, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28956129

RESUMO

OBJECTIVES: To quantitatively assess carpal tunnel syndrome (CTS) with DTI by evaluating two approaches to determine cut-off values. METHODS: In forty patients with CTS diagnosis confirmed by nerve conduction studies (NCs) and 14 healthy subjects (mean age 58.54 and 57.8 years), cross-sectional area (CSA), apparent diffusion coefficient (ADC) and fractional anisotropy (FA) at single and multiple levels with intraobserver agreement were evaluated. RESULTS: Maximum and mean CSA and FA showed significant differences between healthy subjects and patients (12.85 mm2 vs. 28.18 mm2, p < 0.001, and 0.613 vs. 0.524, p=0.007, respectively) (10.12 mm2 vs. 19.9 mm2, p<0.001 and 0.617 vs. 0.54, p=0.003, respectively), but not maximum and mean ADC (p > 0.05). For cut-off values, mean and maximum CSA showed the same sensitivity and specificity (93.3 %). However, mean FA showed better sensitivity than maximum FA (82.6 % vs. 73.9 %), but lower specificity (66.7 % vs. 80 %), and significant correlation for maximum CSA, 97 % (p < 0.01), with good correlation for maximum ADC and FA, 84.5 % (p < 0.01) and 62 % (p=0.056), respectively. CONCLUSIONS: CSA and FA showed significant differences between healthy subjects and patients. Single measurement at maximum CSA is suitable for FA determination. Key Points • DTI showed that FA is stronger than ADC for CTS diagnosis. • Single- and multiple-level approaches were compared to determine FA and ADC. • Single-level evaluation at the thickest MN cross-sectional area is sufficient.


Assuntos
Síndrome do Túnel Carpal/diagnóstico por imagem , Imagem de Tensor de Difusão/métodos , Adulto , Idoso , Anisotropia , Estudos de Casos e Controles , Feminino , Humanos , Interpretação de Imagem Assistida por Computador/métodos , Masculino , Nervo Mediano/diagnóstico por imagem , Pessoa de Meia-Idade , Condução Nervosa , Variações Dependentes do Observador , Sensibilidade e Especificidade
6.
AJR Am J Roentgenol ; 210(6): 1323-1329, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29702022

RESUMO

OBJECTIVE: The purpose of this study was to compare findings of ultrasound (US) with dual-energy CT (DECT) findings in patients presenting with suspected gouty knee arthritis. SUBJECTS AND METHODS: This prospective study included 65 patients (52 men and 13 women; median age, 61.7 years [range, 38-87 years]) with an initial clinical diagnosis of acute gouty knee arthritis who underwent DECT performed using a 128-MDCT scanner and US performed using a 5-18-MHz transducer. Both intra- and extraarticular findings obtained using each modality were tabulated. RESULTS: DECT identified gout as the final diagnosis for 52 of 65 patients (80.0%). An alternative diagnosis was confirmed for the remaining 13 patients. US detected gout in 31 of 52 patients (sensitivity, 59.6%) and produced findings negative for gout in seven of 13 patients (specificity, 53.8%). The double contour sign on US was positive for gout in 23 of 52 patients (44.2%) and negative in 12 of 13 patients (92.3%). Extraarticular urate deposition was identified by DECT in 44 of 52 patients, compared with identification by US in 11 of 52 patients (p < 0.001). CONCLUSION: The sensitivity of US for the diagnosis of gouty knee arthritis is limited, particularly with respect to extraarticular urate deposition. The double contour sign is the single most valuable sign for the assessment of gouty knee arthritis by US.


Assuntos
Artrite Gotosa/diagnóstico por imagem , Articulação do Joelho/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Ultrassonografia/métodos , Doença Aguda , Adulto , Idoso , Idoso de 80 Anos ou mais , Diagnóstico Diferencial , Feminino , Humanos , Imageamento Tridimensional , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Sensibilidade e Especificidade
7.
Eur Radiol ; 25(5): 1356-65, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25501270

RESUMO

OBJECTIVES: To evaluate the automated two-point Dixon screening sequence for the detection and estimated quantification of hepatic iron and fat compared with standard sequences as a reference. METHODS: One hundred and two patients with suspected diffuse liver disease were included in this prospective study. The following MRI protocol was used: 3D-T1-weighted opposed- and in-phase gradient echo with two-point Dixon reconstruction and dual-ratio signal discrimination algorithm ("screening" sequence); fat-saturated, multi-gradient-echo sequence with 12 echoes; gradient-echo T1 FLASH opposed- and in-phase. Bland-Altman plots were generated and correlation coefficients were calculated to compare the sequences. RESULTS: The screening sequence diagnosed fat in 33, iron in 35 and a combination of both in 4 patients. Correlation between R2* values of the screening sequence and the standard relaxometry was excellent (r = 0.988). A slightly lower correlation (r = 0.978) was found between the fat fraction of the screening sequence and the standard sequence. Bland-Altman revealed systematically lower R2* values obtained from the screening sequence and higher fat fraction values obtained with the standard sequence with a rather high variability in agreement. CONCLUSIONS: The screening sequence is a promising method with fast diagnosis of the predominant liver disease. It is capable of estimating the amount of hepatic fat and iron comparable to standard methods. KEY POINTS: • MRI plays a major role in the clarification of diffuse liver disease. • The screening sequence was introduced for the assessment of diffuse liver disease. • It is a fast and automated algorithm for the evaluation of hepatic iron and fat. • It is capable of estimating the amount of hepatic fat and iron.


Assuntos
Fígado Gorduroso/diagnóstico , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Siderose/diagnóstico , Adulto , Idoso , Algoritmos , Feminino , Humanos , Imageamento Tridimensional , Fígado/patologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos
8.
Tech Coloproctol ; 18(2): 165-71, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23681302

RESUMO

BACKGROUND: Successful anal fistula care in complex cases can be assisted by specialized imaging which accurately defines the site of the internal fistula opening and the fistula type. There are currently limited data concerning the clinical indications for and accuracy of transperineal ultrasound (TP-US) in acute perianal sepsis. The aims of this study were to compare the anatomical interpretation of TP-US images with magnetic resonance imaging (MRI) and surgical findings in an unselected patient cohort presenting with acute perianal sepsis. METHODS: Sixty-seven consecutive patients with acute anorectal sepsis referred from the surgical department were examined using TP-US and Gadolinium-enhanced MRI with both examiners blinded to the surgical results. Fistulae were categorized by the Parks' classification of fistula type. RESULTS: Thirty-six abscesses were detected by MRI, 38 by TP-US and 30 by surgical examination. Operatively discordant cases showed only ischiorectal panniculitis. TP-US was more accurate in the diagnosis of superficial sepsis and MRI in the diagnosis of deep-seated perirectal infection. TP-US and MRI show concordance with operative findings in fistula diagnosis with a tendency for TP-US to overdiagnose trans-sphincteric fistulae and MRI to over diagnose extra-sphincteric fistulae. Comparison of TP-US with MRI showed good agreement for perianal abscess diagnosis (τ = 0.82) and for fistula diagnosis (τ = 0.68). For fistulae, TP-US showed moderate agreement with surgery (τ = 0.43) with only fair agreement between MRI and surgery (τ = 0.29). CONCLUSIONS: Transperineal ultrasound complements other imaging modalities in the anatomical diagnosis of acute perianal abscesses and fistulae. It has specific advantages over other techniques and is accurate in the detection of superficially located perirectal sepsis showing concordance with MRI and surgical findings.


Assuntos
Abscesso/diagnóstico por imagem , Canal Anal/diagnóstico por imagem , Imageamento por Ressonância Magnética , Fístula Retal/diagnóstico por imagem , Abscesso/etiologia , Abscesso/cirurgia , Adulto , Meios de Contraste , Feminino , Gadolínio , Humanos , Masculino , Pessoa de Meia-Idade , Imagem Multimodal/métodos , Períneo/diagnóstico por imagem , Fístula Retal/complicações , Fístula Retal/cirurgia , Estudos Retrospectivos , Ultrassonografia
9.
Int J Sports Med ; 34(8): 669-75, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23378173

RESUMO

Until recently, assessment of muscle metabolism was only possible by invasive sampling. 31P magnetic resonance spectroscopy (31P MRS) offers a way to study muscle metabolism non-invasively. The aim of the present study was to use spatially-resolved 31P MRS to assess the metabolism of the quadriceps muscle in sprint-trained, endurance-trained and untrained individuals during exercise and recovery. 5 sprint-trained (STA), 5 endurance-trained (ETA) and 7 untrained individuals (UTI) completed one unlocalized 31P MRS session to measure phosphocreatine (PCr) recovery, and a second session in which spatially-resolved 31P MR spectra were obtained. PCr recovery time constant (τ) was significantly longer in STA (50±17 s) and UTI (41±9 s) than in ETA (30±4 s), (P<0.05). PCr changes during exercise differed between the groups, but were uniform across the different components of the quadriceps within each group. pH during recovery was higher for the ETA than for the UTI (P<0.05) and also higher than for the STA (P<0.01). Muscle volume was greater in STA than in UTI (P<0.05) but not different from ETA. Dynamic 31P MRS revealed considerable differences among endurance and sprint athletes and untrained people. This non-invasive method offers a way to quantify differences between individual muscles and muscle components in athletes compared to untrained individuals.


Assuntos
Metabolismo Energético/fisiologia , Exercício Físico/fisiologia , Resistência Física/fisiologia , Corrida/fisiologia , Adolescente , Adulto , Atletas , Humanos , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética/métodos , Masculino , Fosfocreatina/metabolismo , Músculo Quadríceps/fisiologia , Fatores de Tempo , Adulto Jovem
10.
Eur Radiol ; 22(11): 2478-86, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22645044

RESUMO

OBJECTIVES: To evaluate MRI using T1 and T2* mapping sequences in patients with suspected hepatic iron overload (HIO). METHODS: Twenty-five consecutive patients with clinically suspected HIO were retrospectively studied. All underwent MRI and liver biopsy. For the quantification of liver T2* values we used a fat-saturated multi-echo gradient echo sequence with 12 echoes (TR = 200 ms, TE = 0.99 ms + n × 1.41 ms, flip angle 20°). T1 values were obtained using a fast T1 mapping sequence based on an inversion recovery snapshot FLASH sequence. Parameter maps were analysed using regions of interest. RESULTS: ROC analysis calculated cut-off points at 10.07 ms and 15.47 ms for T2* in the determination of HIO with accuracy 88 %/88 %, sensitivity 84 %/89.5 % and specificity 100 %/83 %. MRI correctly classified 20 patients (80 %). All patients with HIO only had decreased T1 and T2* relaxation times. There was a significant difference in T1 between patients with HIO only and patients with HIO and steatohepatitis (P = 0.018). CONCLUSIONS: MRI-based T2* relaxation diagnoses HIO very accurately, even at low iron concentrations. Important additional information may be obtained by the combination of T1 and T2* mapping. It is a rapid, non-invasive, accurate and reproducible technique for validating the evidence of even low hepatic iron concentrations. KEY POINTS: • Hepatic iron overload causes fibrosis, cirrhosis and increases hepatocellular carcinoma risk. • MRI detects iron because of the field heterogeneity generated by haemosiderin. • T2* relaxation is very accurate in diagnosing hepatic iron overload. • Additional information may be obtained by T1 and T2* mapping.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Sobrecarga de Ferro/diagnóstico , Fígado/patologia , Imageamento por Ressonância Magnética/métodos , Adulto , Idoso , Biópsia , Fígado Gorduroso/diagnóstico , Feminino , Proteína da Hemocromatose , Antígenos de Histocompatibilidade Classe I/genética , Humanos , Masculino , Proteínas de Membrana/genética , Pessoa de Meia-Idade , Polimorfismo Genético , Curva ROC , Reprodutibilidade dos Testes , Estudos Retrospectivos
11.
Histochem Cell Biol ; 134(2): 171-96, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20628754

RESUMO

We are developing a nanoparticulate histochemical reagent designed for histochemistry in living animals (molecular imaging), which should finally be useful in clinical imaging applications. The iterative development procedure employed involves conceptual design of the reagent, synthesis and testing of the reagent, then redesign based on data from the testing; each cycle of testing and development generates a new generation of nanoparticles, and this report describes the synthesis and testing of the third generation. The nanoparticles are based on human serum albumin and the imaging modality selected is magnetic resonance imaging (MRI). Testing the second particle generation with newly introduced techniques revealed the presence of impurities in the final product, therefore we replaced dialysis with diafiltration. We introduced further testing methods including thin layer chromatography, arsenazo III as chromogenic assay for gadolinium, and several versions of polyacrylamide gel electrophoresis, for physicochemical characterisation of the nanoparticles and intermediate synthesis compounds. The high grade of chemical purity achieved by combined application of these methodologies allowed standardised particle sizes to be achieved (low dispersities), and accurate measurement of critical physicochemical parameters influencing particle size and imaging properties. Regression plots confirmed the high purity and standardisation. The good degree of quantitative physicochemical characterisation aided our understanding of the nanoparticles and allowed a conceptual model of them to be prepared. Toxicological screening demonstrated the extremely low toxicity of the particles. The high magnetic resonance relaxivities and enhanced mechanical stability of the particles make them an excellent platform for the further development of MRI molecular imaging.


Assuntos
Meios de Contraste/química , Imageamento por Ressonância Magnética/métodos , Nanopartículas/uso terapêutico , Albumina Sérica/uso terapêutico , Desenho de Fármacos , Estabilidade de Medicamentos , Humanos , Teste de Materiais , Nanopartículas/química , Albumina Sérica/química
12.
Histochem Cell Biol ; 133(4): 375-404, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20174817

RESUMO

To develop a platform for molecular magnetic resonance imaging, we prepared gadolinium-bearing albumin-polylactic acid nanoparticles in the size range 20-40 nm diameter. Iterative cycles of design and testing upscaled the synthesis procedures to gram amounts for physicochemical characterisation and for pharmacokinetic testing. Morphological analyses showed that the nanoparticles were spheroidal with rough surfaces. Particle sizes were measured by direct transmission electron microscopical measurements from negatively contrasted preparations, and by use of photon correlation spectroscopy; the two methods each documented nanoparticle sizes less than 100 nm and generally 10-40 nm diameter, though with significant intrabatch and interbatch variability. The particles' charge sufficed to hold them in suspension. HSA retained its tertiary structure in the particles. The nanoparticles were stable against turbulent flow conditions and against heat, though not against detergents. MRI imaging of liquid columns was possible at nanoparticle concentrations below 10 mg/ml. The particles were non-cytotoxic, non-thrombogenic and non-immunogenic in a range of assay systems developed for toxicity testing of nanoparticles. They were micellar prior to lyophilisation, but loosely structured aggregated masses after lyophilisation and subsequent resuspension. These nanoparticles provide a platform for further development, based on non-toxic materials of low immunogenicity already in clinical use, not expensive, and synthesized using methods which can be upscaled for industrial production.


Assuntos
Meios de Contraste/química , Gadolínio/química , Espectroscopia de Ressonância Magnética , Nanopartículas/química , Nanopartículas/ultraestrutura , Albuminas/química , Albuminas/ultraestrutura , Imageamento por Ressonância Magnética/métodos , Microscopia Eletrônica de Transmissão , Tamanho da Partícula
13.
Histochem Cell Biol ; 131(5): 537-51, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19234714

RESUMO

Visualising vascular endothelial cell function in individual blood microvessels allows elucidation of molecular interactions at the vascular wall, the first barrier between blood-borne therapeutic agent and its target. Functional analysis in situ requires sub-micrometer spatial resolution and tagged molecules generating contrast in living blood vessels. Light microscopy fulfills these requirements, particularly if fluorescent tags deliver the contrast. However, vascular arborisations in living organs defy morpho-functional analysis, filling tissues with closely meshed three-dimensional networks which are inaccessible to optical imaging. We protocol here successful morpho-functional analysis of microvascular processing in a living organ, the human placental cotyledon. Fluorescence-tagged tracer was positionally fixed by snap-freezing, frozen sections were cut, freeze-dried and heat-fixed. A brief histochemical procedure then labelled all vascular elements in the sections, providing fluorescence contrast in two colour channels. Mosaic monochromatic images acquired in both channels delivered high-resolution maps of centimeter-wide tissue areas. Quantitative analysis of the images' greyscale histograms defined objectifiable, reproducible thresholds, used to reduce the images to colour-coded wide-area functional maps tracking placental vascular processing of the tagged molecules. Rapid positional fixing of tracer with reduction of images to maps was combined with ultrastructural tracking to elucidate vascular processing at scales of nanometres and seconds.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Microscopia de Fluorescência/métodos , Placenta/irrigação sanguínea , Placenta/ultraestrutura , Feminino , Angiofluoresceinografia , Humanos , Microscopia Eletrônica de Transmissão , Microvasos/fisiologia , Microvasos/ultraestrutura , Gravidez
14.
Br J Anaesth ; 100(6): 827-33, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18430744

RESUMO

BACKGROUND: Lornoxicam like other non-steroidal anti-inflammatory drugs (NSAIDs) is widely used for postoperative pain therapy. Evaluation of the effect of lornoxicam on cerebral processing of surgical pain was thus the aim of the present functional magnetic resonance imaging (fMRI) study. METHODS: An fMRI-compatible pain model that mimics surgical pain was used to induce pain rated 4-5 on a visual analogue scale (VAS) at the anterior margin of the right tibia in volunteers (n=22) after i.v. administration of saline (n=11) or lornoxicam (0.1 mg kg(-1)) (n=11). RESULTS: Lornoxicam, which significantly reduced pain sensation [VAS: mean (sd) 4.6 (0.7) vs 1.2 (1.5)], completely suppressed pain-induced activation in the SII/operculum, anterior cingulate cortex, insula, parietal (inferior), prefrontal (inferior, medial), temporal (inferior, medial/superior) lobe, cerebellum, and contralateral (e.g. left-sided) postcentral gyrus (SI). Only the hippocampus and the contralateral superior parietal lobe (BA 7) were activated. CONCLUSIONS: As compared with saline, lornoxicam typically suppressed pain-induced brain activation in all regions except the hippocampus. Furthermore, de novo activation was found in the contralateral, superior parietal lobe (BA 7).


Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Encéfalo/efeitos dos fármacos , Dor/fisiopatologia , Piroxicam/análogos & derivados , Adulto , Anti-Inflamatórios não Esteroides/uso terapêutico , Encéfalo/fisiopatologia , Mapeamento Encefálico/métodos , Humanos , Imageamento por Ressonância Magnética , Masculino , Dor/etiologia , Dor/prevenção & controle , Medição da Dor/métodos , Estimulação Física , Piroxicam/farmacologia , Piroxicam/uso terapêutico , Método Simples-Cego
15.
Eur J Radiol ; 102: 74-82, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29685548

RESUMO

PURPOSE: To prospectively evaluate a prototypical 3D turbo-spin-echo proton-density-weighted sequence with compressed sensing and free-stop scan mode for preventing motion artefacts (3D-PD-CS-SPACE free-stop) for knee imaging in a clinical setting. METHODS AND MATERIALS: 80 patients underwent 3T magnetic resonance imaging (MRI) of the knee with our 2D routine protocol and with 3D-PD-CS-SPACE free-stop. In case of a scan-stop caused by motion (images are calculated nevertheless) the sequence was repeated without free-stop mode. All scans were evaluated by 2 radiologists concerning image quality of the 3D-PD-CS-SPACE (with and without free-stop). Important knee structures were further assessed in a lesion based analysis and compared to our reference 2D-PD-fs sequences. RESULTS: Image quality of the 3D-PD-CS-SPACE free-stop was found optimal in 47/80, slightly compromised in 21/80, moderately in 10/80 and severely in 2/80. In 29/80, the free-stop scan mode stopped the 3D-PD-CS-SPACE due to subject motion with a slight increase of image quality at longer effective acquisition times. Compared to the 3D-PD-CS-SPACE with free-stop, the image quality of the acquired 3D-PD-CS-SPACE without free-stop was found equal in 6/29, slightly improved in 13/29, improved with equal contours in 8/29, and improved with sharper contours in 2/29. The lesion based analysis showed a high agreement between the results from the 3D-PD-CS-SPACE free-stop and our 2D-PD-fs routine protocol (overall agreement 96.25%-100%, Cohen's Kappa 0.883-1, p < 0.001). CONCLUSION: 3D-PD-CS-SPACE free-stop is a reliable alternative for standard 2D-PD-fs protocols with acceptable acquisition times.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Articulação do Joelho/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Artefatos , Feminino , Humanos , Traumatismos do Joelho/diagnóstico por imagem , Traumatismos do Joelho/patologia , Articulação do Joelho/patologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Prótons , Reprodutibilidade dos Testes , Adulto Jovem
16.
Eur J Radiol ; 89: 149-155, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28267532

RESUMO

PURPOSE: To evaluate pancreatic iron in patients with human hemochromatosis protein associated hereditary hemochromatosis (HHC) using R2* relaxometry. MATERIALS AND METHODS: 81 patients (58 male, 23 female; median age 49.5, range 10-81 years) with HHC were retrospectively studied. All underwent 1.5T magnetic resonance imaging (MRI) of the abdomen. A fat-saturated multi-gradient echo sequence with 12 echoes (TR=200ms; TE-initial 0.99ms; Delta-TE 1.41ms; 12 echoes; flip-angle: 20°) was used for the R2* quantification of the liver and the pancreas. Parameter maps were analyzed using regions of interest (3 in the liver and 2 in the pancreas) and R2* values were correlated. RESULTS: 59/81 patients had a liver R2*≥70 1/s of which 10/59 patients had a pancreas R2*≥50 1/s. No patient presented with a liver R2*<70 1/s and pancreas R2*≥50 1/s. All patients with pancreas R2* values≥50 1/s had liver R2* values≥70 1/s. ROC analysis resulted in a threshold of 209.4 1/s for liver R2* values to identify HFE positive patients with pancreas R2* values≥50 1/s with a median specificity of 78.87% and a median sensitivity of 90%. CONCLUSION: In patients with HHC R2* relaxometry of the pancreas should be performed when liver iron overload is present and can be omitted in cases with no sign of hepatic iron.


Assuntos
Proteína da Hemocromatose/genética , Hemocromatose/genética , Pâncreas/patologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Feminino , Hemocromatose/patologia , Humanos , Ferro/metabolismo , Sobrecarga de Ferro/patologia , Fígado/patologia , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Curva ROC , Estudos Retrospectivos , Sensibilidade e Especificidade , Adulto Jovem
17.
J Control Release ; 115(1): 78-84, 2006 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-16901569

RESUMO

The aim of this study was to compare different oral delivery systems based on the thiolated polymer polycarbophil-cysteine (PCP-Cys) and to provide evidence for the validity of the hypothesis that unhydrated polymers provide better mucoadhesion in vivo. To achieve dry polymer application, a new, experimental dosage form named Eutex (made of Eudragit L100-55 and latex) capsule has been developed. Magnetic resonance imaging was used to localize the point of release of the thiolated polymer from the application forms via the positive magnetic resonance signal from a gadolinium complex (Gd-DTPA). In vivo mucoadhesion was determined by ascertaining the residence time of the fluorescence-tagged thiomer on intestinal mucosa after 3 h. Results showed that in comparison to conventional application forms the Eutex capsules led to 1.9-fold higher mucoadhesive properties of PCP-Cys when compared to application with a conventional enteric-coated capsule, and to 1.4-fold higher mucoadhesion when compared to administration with an enteric-coated tablet of the thiomer. The findings of this study should contribute to the understanding of mucoadhesion and mucoadhesion influencing parameters in vivo and should therefore be of considerable interest for the development of future mucoadhesive oral drug delivery dosage forms.


Assuntos
Mucosa/metabolismo , Compostos de Sulfidrila/química , Animais , Líquidos Corporais , Meios de Contraste , Fluoresceína , Gadolínio DTPA/farmacocinética , Esvaziamento Gástrico/fisiologia , Técnicas In Vitro , Absorção Intestinal/efeitos dos fármacos , Látex , Imageamento por Ressonância Magnética , Masculino , Metoclopramida/farmacologia , Microscopia de Fluorescência , Polímeros/química , Ácidos Polimetacrílicos , Ratos , Ratos Sprague-Dawley , Espectrometria de Fluorescência , Suínos , Comprimidos com Revestimento Entérico
20.
Cancer Res ; 61(6): 2513-6, 2001 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-11289123

RESUMO

Contrast enhanced dynamic studies of malignant tumors performed by computed tomography or magnetic resonance imaging (MRI) are increasingly applied to characterize tumor microcirculation for the prediction of therapy outcome. The aim of our study was to correlate perfusion index (PI) values determined in primary rectal carcinoma before chemoradiation with therapy outcome. In 17 patients with clinically staged T3 primary rectal carcinoma, dynamic MRI was performed before the onset of therapy using an ultrafast T1-mapping sequence. On the basis of the acquired data sets, PI values were calculated on a pixel-by-pixel basis. To characterize the heterogeneity of tumor microcirculation, relative cumulative frequency histograms of PI values within the tumors were computed. Subsequent resection of the tumors allowed correlating PI with histopathological classification. In 12 of 17 patients, T-downstaging as a response to therapy was found, whereas in the remaining 5 patients no therapy response was observed after chemoradiation. A statistically significant difference between both groups was found for the mean PI (P < 0.001; 8.5+/-1.7 ml/min/100 g versus 11.4+/-0.7 ml/min/100 g). Analyzing the cumulative frequency histograms for both groups revealed an optimal discrimination for a P1 value of 12.6 ml/min/100 g. The fraction of pixels in the tumor with PI values larger than 12.6 ml/min/100 g was significantly different (P < 0.001) between therapy-responding (3+/-3.6%) and therapy-nonresponding tumors (21+/-4.3%). The results indicate either a reduced supply of nutrients as well as chemotherapeutic agents attributable to increased shunt flow or highly aggressive tumor cell clusters characterized by increased angiogenic activity. Noninvasive PI measurements by dynamic MRI in rectal carcinoma before therapy seem to be of predictive value for therapy outcome in patients scheduled for preoperative chemoradiation.


Assuntos
Adenocarcinoma/irrigação sanguínea , Adenocarcinoma/terapia , Neoplasias Retais/irrigação sanguínea , Neoplasias Retais/terapia , Adenocarcinoma/patologia , Adulto , Idoso , Antimetabólitos Antineoplásicos/uso terapêutico , Terapia Combinada , Fluoruracila/uso terapêutico , Humanos , Angiografia por Ressonância Magnética , Microcirculação , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Valor Preditivo dos Testes , Cuidados Pré-Operatórios , Neoplasias Retais/patologia , Resultado do Tratamento
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