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2.
Pediatr Radiol ; 31(8): 589-93, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11550773

RESUMO

OBJECTIVE: To evaluate a gadolinium-enhanced MR angiography (Gd-MRA) imaging protocol for the assessment of thoracic vessels using double-dose gadolinium and quiet breathing. An animal model was used to simulate imaging in infants and young children. MATERIAL AND METHODS: Six baboons (Papio anubis), mean weight 5.7 kg, were sedated and intubated. After the injection of double-dose Gd-DTPA (0.2 mmol/kg) through a peripheral vein, a coronal spoiled 3D gradient-echo volume acquisition was obtained during quiet breathing. Two radiologists reviewed the images for visualization of aortic arch, brachiocephalic vessel origins, pulmonary arteries (central, upper lobe and descending branches), and pulmonary veins (upper and lower). RESULTS: Visualization was excellent for the aortic arch, brachiocephalic vessel origins, and pulmonary arteries, including the hilar branches. Visualization was excellent for the lower and right upper pulmonary veins and fair for the left upper pulmonary vein. There was excellent agreement between radiologists. CONCLUSION: Imaging of thoracic vessels with Gd-MRA using double gadolinium during quiet breathing was effective in our animal model. The advantages of this technique include a short imaging time and depiction of vascular segments--branches of pulmonary arteries and intraparenchymal segments of pulmonary veins--not optimally visualized with other non-invasive imaging techniques.


Assuntos
Meios de Contraste/administração & dosagem , Gadolínio DTPA/administração & dosagem , Angiografia por Ressonância Magnética/métodos , Tórax/irrigação sanguínea , Animais , Aorta Torácica/anatomia & histologia , Veias Braquiocefálicas/anatomia & histologia , Processamento de Imagem Assistida por Computador , Modelos Animais , Papio , Artéria Pulmonar/anatomia & histologia , Veias Pulmonares/anatomia & histologia , Respiração
3.
Thromb Haemost ; 85(3): 423-9, 2001 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11307808

RESUMO

Inhibition of P-selectin by antibody or selectin antagonist decreases inflammation and thrombosis. This study evaluates the dose-response relationship using a selectin receptor antagonist. Eight male baboons (Papio anubis) underwent inferior vena caval thrombosis using a 6 h balloon occlusion model. Three animals received 500 microg/kg P-selectin antagonist (rPSGL-Ig) and five 1 mg/kg rPSGL-Ig with or without a non-anticoagulant dose of Dalteparin. These animals were compared to our published results in this model with 4 saline controls and 8 animals that received 4 mg/kg rPSGL-Ig. A statistically significant dose-response relationship existed between rPSGL-Ig dose and thrombosis (p < 0.01), and between rPSGL-Ig dose and spontaneous recanalization (p<0.05). Inflammatory assessment revealed decreased gadolinium enhancement in all rPSGL-Ig groups compared to previously reported control, despite no significant differences in inflammatory cell extravasation. No dose of rPSGL-Ig caused anticoagulation. Selectin antagonism results in a dose-dependent decrease in thrombosis and increase in spontaneous recanalization.


Assuntos
Glicoproteínas de Membrana/administração & dosagem , Selectina-P/efeitos dos fármacos , Trombose Venosa/prevenção & controle , Animais , Anticoagulantes/administração & dosagem , Oclusão com Balão , Dalteparina/administração & dosagem , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Antagonismo de Drogas , Quimioterapia Combinada , Inflamação/tratamento farmacológico , Masculino , Papio , Trombose Venosa/tratamento farmacológico
4.
Invest Radiol ; 36(5): 283-91, 2001 May.
Artigo em Inglês | MEDLINE | ID: mdl-11323516

RESUMO

RATIONALE AND OBJECTIVES: To optimize three-dimensional gadolinium magnetic resonance angiography (3D-Gd-MRA) of the aorta and runoff vessels by addressing fundamentally different requirements for temporal and spatial resolution in a single semiautomated examination. METHODS: The technique was designed to obtain pure arterial-phase 3D-Gd-MR angiograms with adequate spatial resolution for each station while avoiding incomplete enhancement due to delayed filling vessels as well as venous overlay. During gadolinium-chelate infusion, a breath-held multiphase 3D-Gd-MRA scan was initiated in the aorta by automatic triggering, followed by automatic table movement. The acquisition was tailored to the vessels of interest by tilting of the 3D volumes. A spatial resolution of 1.7 x 1.2 x 0.8 mm in the calves was achieved by use of elliptical-centric k-space reordering. Signal-to-noise ratio was maximized with a 12-element peripheral vascular coil. Twelve patients with peripheral vascular disease were studied. RESULTS: In cases of aortic occlusive disease (n = 2), dissections (n = 3), or aneurysms (n = 4), substantially delayed fill-in of reconstituted arteries, false lumens, or aneurysmal segments occurred, which was detected only on the later 3D-Gd-MRA phase. High-resolution arterial-phase scans in the calves were obtained, with only one case of substantial venous overlay. Correlation to digital subtraction angiography revealed excellent agreement of pathological findings. CONCLUSIONS: Multiphase-multistep 3D-Gd-MRA reduces the limitations of standard 3D-Gd-MRA techniques with respect to anatomic coverage, spatial resolution, and nonuniform arterial vessel enhancement.


Assuntos
Aorta Abdominal/diagnóstico por imagem , Doenças da Aorta/diagnóstico por imagem , Meios de Contraste , Gadolínio DTPA , Perna (Membro)/irrigação sanguínea , Perna (Membro)/diagnóstico por imagem , Angiografia por Ressonância Magnética/métodos , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Radiografia
5.
Radiology ; 217(2): 581-6, 2000 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11058664

RESUMO

At arterial phase gadolinium-enhanced magnetic resonance (MR) angiography, artifactual stenosis of the subclavian artery is sometimes seen adjacent to the subclavian vein on the side of the contrast material injection. Experiments in phantoms and in 19 patients showed increased artifact with longer echo time and higher concentration of injected contrast material. An effective method to substantially decrease this susceptibility artifact was threefold dilution of gadopentetate dimeglumine and use of a short echo time (1 msec).


Assuntos
Artefatos , Meios de Contraste/administração & dosagem , Gadolínio DTPA , Angiografia por Ressonância Magnética , Artéria Subclávia/anatomia & histologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Feminino , Gadolínio DTPA/administração & dosagem , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Imagens de Fantasmas , Veia Subclávia/anatomia & histologia
6.
J Immunol ; 164(4): 2131-41, 2000 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-10657667

RESUMO

Post-thrombotic inflammation probably contributes to chronic venous insufficiency, and little effective treatment exists. IL-10 is an anti-inflammatory cytokine that previously has been shown to decrease perithrombotic inflammation and thrombosis. We investigated in a rat model whether local expression of viral IL-10 (vIL-10) in a segment of vein that undergoes thrombosis would confer an anti-inflammatory effect and how this effect might be mediated. Rats underwent inferior vena cava isolation, cannulation, and instillation of saline or adenovirus encoding either beta-galactosidase or vIL-10. Two days after transfection, thrombosis was induced, 2 days after this the rats underwent gadolinium (Gd)-enhanced magnetic resonance venography exam, and the vein segments were harvested. Tissue transfection was confirmed by either RT-PCR of vIL-10 or positive 5-bromo-4-chloro-3-indolyl beta-d-galactopyranoside (X-Gal) staining. vIL-10 significantly decreased both leukocyte vein wall extravasation and area of Gd enhancement compared with those in controls, suggesting decreased inflammation. Immunohistochemistry demonstrated decreased endothelial border staining of P- and E-selectin, while ELISA of vein tissue homogenates revealed significantly decreased P- and E-selectin and ICAM-1 levels in the vIL-10 group compared with those in controls. Importantly, native cellular IL-10 was not significantly different between the groups. However, neither clot weight nor coagulation indexes, including tissue factor activity, tissue factor Ag, or von Willebrand factor levels, were significantly affected by local vIL-10 expression. These data suggest that local transfection of vIL-10 decreases venous thrombosis-associated inflammation and cell adhesion molecule expression, but does not directly affect local procoagulant activity.


Assuntos
Moléculas de Adesão Celular/biossíntese , Técnicas de Transferência de Genes , Interleucina-10/genética , Trombose Venosa/patologia , Trombose Venosa/prevenção & controle , Proteínas Virais/genética , Animais , Testes de Coagulação Sanguínea , Moléculas de Adesão Celular/metabolismo , Citocinas/análise , Modelos Animais de Doenças , Epoprostenol/análise , Herpesvirus Humano 4/genética , Interleucina-10/biossíntese , Masculino , Ratos , Ratos Sprague-Dawley , Tromboplastina/metabolismo , Transfecção , Veia Cava Inferior/metabolismo , Veia Cava Inferior/patologia , Trombose Venosa/sangue , Trombose Venosa/imunologia , Proteínas Virais/biossíntese
7.
J Vasc Surg ; 31(2): 309-24, 2000 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10664500

RESUMO

OBJECTIVE: This study was performed to determine the effectiveness of recombinant P-selectin glycoprotein ligand Ig (rPSGL-Ig) pretreatment to decrease thrombosis and inflammation in experimental venous thrombosis. rPSGL-Ig, a unique mucin-like glycoprotein, has a high affinity for P-selectin. METHODS: Twelve juvenile baboons underwent inferior vena cava (IVC) thrombosis with temporary 6-hour IVC balloon occlusion. Before balloon placement, the animals received rPSGL-Ig (4 mg/kg; n = 8) or saline solution for control (n = 4). The animals underwent evaluation with duplex ultrasound scan imaging, magnetic resonance venography (MRV), phlebography, coagulation profile, and tissue analysis at death for cytokines and vein wall leukocyte morphometrics. With the MRV results, thrombus development, thrombus resolution, and inflammation (gadolinium; square millimeters of enhancement) were assessed. RESULTS: Each animal provided two time points for evaluation (days 2 and 6 after balloon occlusion). A significant decrease in IVC thrombosis between balloons was found in the rPSGL-Ig animals (1 of 16) versus the control animals (5 of 8; P <.01). The MRV results showed significantly less enhancement in the rPSGL-Ig animals at days 2 and 6 (P <.05). Spontaneous thrombus resolution (including balloon sites) was significantly greater from day 2 to day 6 in the rPSGL-Ig animals versus the control animals (23% vs 2%; P <.001), without pulmonary embolism. Lower interleukin-8, platelet factor IV, and monocyte chemotactic protein-1 levels were found in rPSGL-Ig vein walls without significant differences in vein wall leukocyte morphometrics. There were significantly lower D-dimer levels in the rPSGL-Ig-treated animals (P <.05), but there were no differences in measurements of coagulation. Adequate circulating rPSGL-Ig levels were documented. CONCLUSION: Pretreatment with rPSGL-Ig results in: (1) a significant inhibition of thrombosis and vein wall inflammation; (2) a decrease in vein wall cytokine expression; and (3) a promotion of thrombus resolution. Inflammatory inhibition by rPSGL-Ig without anticoagulation therapy provides effective venous thrombosis prophylaxis in experimental venous thrombosis.


Assuntos
Glicoproteínas de Membrana/antagonistas & inibidores , Glicoproteínas de Membrana/uso terapêutico , Mucinas/antagonistas & inibidores , Selectina-P/metabolismo , Veia Cava Inferior , Trombose Venosa/prevenção & controle , Animais , Anticoagulantes , Avaliação Pré-Clínica de Medicamentos , Hemodinâmica/efeitos dos fármacos , Ligantes , Angiografia por Ressonância Magnética , Papio , Radiografia , Proteínas Recombinantes/uso terapêutico , Ultrassonografia , Veia Cava Inferior/diagnóstico por imagem , Veia Cava Inferior/patologia , Trombose Venosa/sangue , Trombose Venosa/diagnóstico , Trombose Venosa/patologia , Trombose Venosa/fisiopatologia
8.
J Invest Surg ; 12(3): 151-6, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-10421517

RESUMO

Venous thrombosis is associated with a significant inflammatory response in the vein wall, which can be imaged noninvasively with gadolinium (Gd)-enhanced magnetic resonance venography (MRV). Interleukin-10 (IL-10), a naturally occurring anti-inflammatory cytokine, has been found to decrease the inflammatory response at the proper dosage and timing of administration. The present study determines if MRV with Gd is useful in a rat model of stasis-induced venous thrombosis to document the anti-inflammatory effects of rIL-10. Rats underwent laparotomy and ligation of the inferior vena cava (IVC). Animals were infused with rIL-10 at 2.5 microg (n = 6), rIL-10 at 10 microg (n = 6), or rIL-10 at 40 microg (n = 6). Six animals without IVC ligation or drug infusion served as controls. Two days after thrombosis induction, the rats underwent MRV with both time-of-flight imaging and pre/post-Gd T1-weighted imaging. Inflammation was analyzed by measuring the area of Gd enhancement at the point of IVC thrombosis. Enhancement area was also measured in the distal IVC where flow persisted. All animals with IVC ligation developed thrombosis, and all control rats were free of thrombus. In areas where flow remained, the area of enhancement was 1.8 +/- 0.4 mm2, while controls demonstrated 3.8 +/- 1.0 mm2 enhancement. Enhancement was significantly greater in all groups at the level of thrombus compared to the area of distal IVC flow and control IVCs (p < .001). Animals receiving rIL-10 at 40 microg revealed the most enhancement, 32.7 +/- 6.2 mm2, while the least enhancement was noted with 2.5 microg, 14.7 +/- 1.5 mm2 (p < .05). In conclusion, Gd-enhanced MRV was found useful in this rat model of stasis-induced venous thrombosis to document inflammation noninvasively and to evaluate the effects of anti-inflammatory interventions during stasis-induced IVC venous thrombosis.


Assuntos
Gadolínio , Aumento da Imagem , Angiografia por Ressonância Magnética , Trombose Venosa/diagnóstico , Animais , Modelos Animais de Doenças , Ratos , Ratos Sprague-Dawley
9.
Pediatr Radiol ; 29(5): 367-71, 1999 May.
Artigo em Inglês | MEDLINE | ID: mdl-10382217

RESUMO

BACKGROUND: Literature on magnetic resonance imaging (MR) evaluation of inflammatory joint effusions is sparse. OBJECTIVE: To describe an animal model for studying infectious and non-infectious joint effusions with magnetic resonance imaging. MATERIALS AND METHODS: Ten rabbit knees with septic arthritis and four with talc synovitis were imaged with MR. Contralateral knees injected with saline served as controls. Fat saturation T2-weighted and gadolinium-enhanced T1-weighted images were assessed for joint effusion, and periarticular and adjacent intraosseous increased signal or enhancement. Each knee was cultured and underwent pathologic examination. RESULTS: Both Staphylococcus aureus and talc produced effusions in all knees. The degree of periarticular signal and enhancement was greater in infected knees than talc-injected knees. No abnormal enhancement was seen within bone. Pathologic examination showed a greater degree of inflammation and joint destruction in the infected knees, but no evidence of osteomyelitis. CONCLUSION: A greater degree of abnormal signal and enhancement seen on MR suggests a more vigorous inflammatory process, as seen with septic arthritis. In spite of advanced septic arthritis, no enhancement was evident within bone, suggesting that enhancement within bone is not an expected finding in isolated septic arthritis and should raise concern for osteomyelitis.


Assuntos
Imageamento por Ressonância Magnética , Infecções Estafilocócicas/diagnóstico , Membrana Sinovial/patologia , Sinovite/diagnóstico , Animais , Diagnóstico Diferencial , Modelos Animais de Doenças , Exsudatos e Transudatos , Processamento de Imagem Assistida por Computador , Joelho/microbiologia , Joelho/patologia , Coelhos , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/isolamento & purificação , Membrana Sinovial/microbiologia , Sinovite/induzido quimicamente , Sinovite/microbiologia , Talco/toxicidade
10.
Med Phys ; 26(5): 707-14, 1999 May.
Artigo em Inglês | MEDLINE | ID: mdl-10360530

RESUMO

Quantitative analysis of dynamic gadolinium-DTPA (diethylenetriamine pentaacetic acid) enhanced magnetic resonance imaging (MRI) is emerging as a highly sensitive tool for detecting malignant breast tissue. Three-dimensional rapid imaging techniques, such as keyhole MRI, yield high temporal sampling rates to accurately track contrast enhancement and washout in lesions over the course of multiple volume acquisitions. Patient motion during the dynamic acquisitions is a limiting factor that degrades the image quality, particularly of subsequent subtraction images used to identify and quantitatively evaluate regions suggestive of malignancy. Keyhole imaging is particularly sensitive to motion since datasets acquired over an extended period are combined in k-space. In this study, motion is modeled as set of translations in each of the three orthogonal dimensions. The specific objective of the study is to develop and implement an algorithm to correct the consequent phase shifts in k-space data prior to offline keyhole reconstruction three-dimensional (3D) volume breast MR acquisitions.


Assuntos
Gadolínio , Processamento de Imagem Assistida por Computador/métodos , Mamografia/métodos , Algoritmos , Simulação por Computador , Humanos , Imageamento por Ressonância Magnética , Modelos Teóricos , Imagens de Fantasmas , Fatores de Tempo
11.
Invest Radiol ; 33(9): 506-14, 1998 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-9766034

RESUMO

RATIONALE AND OBJECTIVES: The authors review different imaging and contrast-media infusion strategies for arterial-phase three-dimensional (3D) gadolinium-enhanced magnetic resonance angiography (Gd-MRA). METHODS: The influence of physicochemical factors on the infusion of contrast media, including viscosity, flow rate, inline pressure, and cannula size, is assessed. The combination of manual or automated contrast-media administration with timing-dependent or -independent 3D Gd-MRA techniques is reviewed regarding the aspects of effectiveness, robustness, image quality, and costs. RESULTS: For effective bolus delivery with high flow rates, the type and temperature of the contrast media, the size of the cannula, and an immediate saline flush must be considered. Timing-dependent techniques based on a test bolus and using automated contrast-media infusion as well as timing independent techniques such as MR SmartPrep or multiphase 3D Gd-MRA by using a manual injection with a SmartSet tubing set, are all effective procedures for arterial phase 3D Gd-MRA. CONCLUSIONS: Manual contrast-media injection with a tubing set can be used for timing-independent MRA techniques. The multiphase 3D Gd-MRA approach seems to be favorable for different MR systems, robustness, and speed.


Assuntos
Meios de Contraste/administração & dosagem , Gadolínio/administração & dosagem , Angiografia por Ressonância Magnética , Artéria Renal/patologia , Meios de Contraste/economia , Análise Custo-Benefício , Sistemas de Liberação de Medicamentos/economia , Sistemas de Liberação de Medicamentos/instrumentação , Gadolínio DTPA/administração & dosagem , Gadolínio DTPA/economia , Compostos Heterocíclicos/administração & dosagem , Humanos , Aumento da Imagem/métodos , Injeções Intravenosas , Angiografia por Ressonância Magnética/economia , Angiografia por Ressonância Magnética/métodos , Compostos Organometálicos/administração & dosagem , Obstrução da Artéria Renal/diagnóstico , Reprodutibilidade dos Testes , Fatores de Tempo
12.
Invest Radiol ; 33(9): 660-9, 1998 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-9766051

RESUMO

RATIONALE AND OBJECTIVES: The anatomic and hemodynamic renal changes after renal arterial revascularization (RAR) were investigated. METHODS: Thirty-seven kidneys and 40 renal arteries were evaluated in 20 patients by using magnetic resonance imaging/magnetic resonance angiography (MRI/MRA) to assess pre- and post-RAR renal length and mass, parenchymal thickness, renal enhancement, renal artery caliber, poststenotic dilation, and signal dephasing on 3D phase contrast (PC). The kidneys and renal arteries were segregated into three groups. Group 1 included 16 patients who benefited from RAR (defined as clinical improvement based on decreased serum creatinine or fewer number of antihypertensive medications) in whom 26 renal arteries in 25 kidneys were studied. Intervention included renal artery endarterectomy (n = 20); aortorenal bypass (n = 3); renal artery reimplantation (n = 3); and percutaneous transluminal angioplasty (PTA; n = 1). A total of 27 interventions was performed, as PTA failed for one patient who subsequently underwent aortorenal bypass before reimaging. Group 2 included four patients who did not clinically benefit. A total of eight revascularized arteries were studied in seven kidneys. In group 3, six renal arteries in five kidneys from groups 1 and 2 without RAS/RAR were analyzed as an internal control. RESULTS: Technical success (defined as increased vessel caliber after intervention) was achieved in 33 of the 34 revascularized arteries. A statistically significant increase in renal length occurred regardless of clinical outcome (pre-RAR, 9.5 cm; post-RAR, 10.5 cm; P < 0.0001). Parenchymal thickness and renal mass, however, improved only in patients who benefited clinically from RAR. Parenchymal enhancement was unchanged in any of the groups studied. No significant morphologic changes were detected in the control group. CONCLUSIONS: Magnetic resonance imaging and Gd-MRA detect anatomic and hemodynamic changes that occur with renal revascularization.


Assuntos
Meios de Contraste/administração & dosagem , Gadolínio , Angiografia por Ressonância Magnética , Obstrução da Artéria Renal/diagnóstico , Artéria Renal/patologia , Procedimentos Cirúrgicos Vasculares , Adulto , Idoso , Velocidade do Fluxo Sanguíneo , Feminino , Seguimentos , Gadolínio/administração & dosagem , Humanos , Aumento da Imagem/métodos , Infusões Intravenosas , Masculino , Pessoa de Meia-Idade , Artéria Renal/fisiopatologia , Obstrução da Artéria Renal/fisiopatologia , Obstrução da Artéria Renal/cirurgia , Resultado do Tratamento
13.
Invest Radiol ; 33(9): 699-708, 1998 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-9766055

RESUMO

RATIONALE AND OBJECTIVES: Our purpose was to investigate a "blood pool" contrast agent for abdominal and thoracic MR angiography by comparison with standard ionic and nonionic gadolinium-based contrast agents, which redistribute into the extracellular fluid compartment. METHODS: Abdominal and thoracic MR angiography was performed in three adult dogs using a three-dimensional spoiled gradient echo pulse sequence before and after intravenous administration of one of three gadolinium-based contrast agents (gadopentetate dimeglumine, gadobutrol, and gadomer-17). Each compound was tested at five different doses in all three dogs. Quantitative analysis of signal-to-noise ratio (SNR) was performed in the aorta, inferior vena cava (IVC), liver, spleen, kidney (medulla and cortex), fat, and muscle. RESULTS: Gadomer-17 improved visualization of vascular anatomy at doses of 0.025, 0.05, 0.1, and 0.2 mmol/kg with three-fold greater aorta SNR during the arterial phase and more than four-fold greater aorta and IVC SNR during the equilibrium phase, in comparison with gadopentetate dimeglumine and gadobutrol at equal doses. CONCLUSIONS: Gadomer-17 is a promising contrast agent for both arterial phase and equilibrium phase MR angiography.


Assuntos
Vasos Sanguíneos/anatomia & histologia , Meios de Contraste/administração & dosagem , Gadolínio , Angiografia por Ressonância Magnética , Tecido Adiposo/irrigação sanguínea , Animais , Aorta/anatomia & histologia , Cães , Feminino , Seguimentos , Gadolínio/administração & dosagem , Gadolínio DTPA/administração & dosagem , Aumento da Imagem , Infusões Intravenosas , Rim/irrigação sanguínea , Fígado/irrigação sanguínea , Angiografia por Ressonância Magnética/métodos , Músculo Esquelético/irrigação sanguínea , Compostos Organometálicos/administração & dosagem , Sensibilidade e Especificidade , Veia Cava Inferior/anatomia & histologia
14.
AJR Am J Roentgenol ; 170(3): 747-52, 1998 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-9490968

RESUMO

OBJECTIVE: The purpose of this study was to analyze the CT contrast enhancement washout curves of adrenal masses and to determine the earliest time after initial enhancement that differentiation of adenomas from nonadenomas is possible. MATERIALS AND METHODS: Contrast enhancement washout curves were generated after delayed contrast-enhanced CT scans of 52 adrenal adenomas and 24 nonadenomas. The optimal threshold value and corresponding sensitivity and specificity for the diagnosis of adenoma were determined according to attenuation values. Also, we calculated the percentage and relative percentage of enhancement washout at time delays from 5 to 45 min after initial enhancement. RESULTS: The mean percentage of enhancement washout for adrenal adenomas was 51% at 5 min and 70% at 15 min, compared with 8% and 20%, respectively, for nonadenomas. The sensitivity and specificity for the diagnosis of adenoma were both 96% at a threshold attenuation value of 37 H on the 15-min delayed enhanced scan. CONCLUSION: On CT, adrenal adenomas show a much earlier and more rapid washout of contrast enhancement than do nonadenomas. Adenomas and nonadenomas can be differentiated by attenuation values or the percentage or relative percentage of washout as early as 5-15 min after enhancement.


Assuntos
Adenoma/diagnóstico por imagem , Neoplasias das Glândulas Suprarrenais/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Adulto , Idoso , Idoso de 80 Anos ou mais , Meios de Contraste , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Curva ROC , Sensibilidade e Especificidade
15.
Radiology ; 205(1): 128-36, 1997 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9314974

RESUMO

PURPOSE: To identify magnetic resonance (MR) angiographic features of hemodynamically significant renal artery stenosis. MATERIALS AND METHODS: Forty-seven patients underwent MR angiography of the renal arteries, including T1-weighted spin-echo and three-dimensional gadolinium-enhanced spoiled gradient-echo and three-dimensional phase-contrast pulse sequences, followed by renal revascularization. Thirty-five patients (52 arteries) were identified who benefited from renal revascularization, which indicated that they had hemodynamically significant renal artery stenoses. Kidney length, cortical thickness, parenchymal enhancement, and poststenotic dilatation were measured. Arteries were also examined for signal drop-out (dephasing) on phase-contrast angiograms; dephasing was considered severe if the stenotic artery appeared occluded on phase-contrast angiograms. RESULTS: Poststenotic dilatation of greater than 20% was present in 36 (59%) of 52 hemodynamically significant renal artery stenoses, and severe dephasing was present in 45 (87%) of 52. In patients with unilateral hemodynamically significant stenosis or occlusion, mean ischemic kidney length was reduced to 9.3 cm compared with 10.7 cm for the contralateral normal kidney (P = .009), mean parenchymal thickness was reduced (1.2 vs 1.7 cm; P < .001), and mean parenchymal enhancement was 15% less on the ischemic side (P = .05). Severe dephasing on phase-contrast angiograms was present in nine (75%) of 12 unilateral hemodynamically significant stenoses but in only one contralateral normal renal artery (P < .001). CONCLUSION: MR angiography depicts features of renal artery stenosis that are markers of hemodynamic significance.


Assuntos
Arteriosclerose/diagnóstico , Angiografia por Ressonância Magnética , Obstrução da Artéria Renal/diagnóstico , Adulto , Idoso , Idoso de 80 Anos ou mais , Meios de Contraste , Feminino , Gadolínio , Gadolínio DTPA , Hemodinâmica , Humanos , Masculino , Pessoa de Meia-Idade , Compostos Organometálicos , Ácido Pentético/análogos & derivados , Artéria Renal/patologia , Obstrução da Artéria Renal/fisiopatologia , Obstrução da Artéria Renal/terapia
16.
J Vasc Surg ; 25(5): 816-27; discussion 828, 1997 May.
Artigo em Inglês | MEDLINE | ID: mdl-9152309

RESUMO

PURPOSE: Venous thrombosis and inflammation are interrelated. P-selectin contributes to activation of leukocyte-mediated inflammation. Therefore, we hypothesized that the neutralization of P-selectin would decrease vein wall inflammation and thrombosis. METHODS: Twelve baboons underwent infrarenal inferior vena caval balloon occlusion to induce thrombosis. Two groups of four baboons received neutralizing intravenous anti-P-selectin antibody (PSab) GA6 or CY1748 before occlusion and at days 2 and 4. Four baboons received saline control injections. One baboon per group was killed at days 2, 6, and 13, and at 2 months. Analysis included phlebography, ultrasound, gadolinium (Gd)-enhanced magnetic resonance venography (reflecting vein wall inflammation), and histologic, morphometric, and protein evaluation of the vein wall. Thrombus presence or absence was assessed. RESULTS: By day 2 in PSab baboons, vein wall Gd enhancement was decreased in the mid-inferior vena cava and the right iliac vein (p < 0.05; GA6 vs control baboons), normalizing by 2 months. The mid-inferior vena cava revealed fewer neutrophils and total leukocytes in PSab baboons; however, for GA6 in the right iliac vein these decreases were not present despite the absence of Gd enhancement; they were decreased with CY1748. PSab baboons demonstrated significantly less thrombus than control baboons (p < 0.01, GA6 and CY1748 vs control baboons). CONCLUSIONS: Anti-P-selectin antibody decreases vein wall inflammation and thrombus formation. Inhibition of P-selectin may be useful in venous thrombosis prophylaxis.


Assuntos
Anticorpos Monoclonais/uso terapêutico , Veia Ilíaca , Selectina-P/imunologia , Trombose/tratamento farmacológico , Vasculite/tratamento farmacológico , Veia Cava Inferior , Doença Aguda , Animais , Anticorpos/sangue , Doença Crônica , Meios de Contraste , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos , Gadolínio , Veia Ilíaca/diagnóstico por imagem , Veia Ilíaca/patologia , Angiografia por Ressonância Magnética , Papio , Radiografia , Trombose/diagnóstico , Trombose/imunologia , Trombose/patologia , Fatores de Tempo , Ultrassonografia , Vasculite/diagnóstico , Vasculite/imunologia , Vasculite/patologia , Veia Cava Inferior/diagnóstico por imagem , Veia Cava Inferior/patologia
17.
Radiology ; 203(1): 109-14, 1997 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9122376

RESUMO

PURPOSE: To improve gadolinium-enhanced magnetic resonance (MR) angiogram quality by automatically synchronizing acquisition of central k-space image data with the arterial phase of contrast material bolus infusion. MATERIALS AND METHODS: A spin-echo pulse sequence with orthogonal 90 degrees and 180 degrees pulses was used to monitor signal in a single 4 x 4 x 12-cm voxel that encompassed a segment of aorta. An increase in signal that corresponded to the arrival of gadolinium was used to trigger three-dimensional, spoiled gradient-echo abdominal MR angiography in 50 adult patients. RESULTS: Arterial signal intensity increased 28-fold with automatic compared to 19-fold with manual triggering (P < .05) at an approximate dose of 0.3 mmol/kg. Automatic triggering with a lower dose (approximately 0.2 mmol/kg) resulted in 20-fold arterial enhancement, which is comparable with enhancement after manual triggering at the high dose. In addition, venous enhancement was less (1.5-fold) with automatic than with manual (3.5-fold) triggering at the same dose (P < .05). CONCLUSION: Automatic triggering results in improved arterial-tovenous contrast. It increases arterial enhancement or enables MR angiograms to be obtained with less contrast material. The authors now routinely use this technique for aortorenal imaging with a gadolinium-based contrast material dose of 20 mmol (40 mL) in patients who weigh more than 50 kg and 10 mmol (20 mL) in patients who weigh less than 50 kg.


Assuntos
Abdome/irrigação sanguínea , Aorta/patologia , Meios de Contraste , Angiografia por Ressonância Magnética , Combinação de Medicamentos , Feminino , Gadolínio , Gadolínio DTPA , Humanos , Masculino , Meglumina , Pessoa de Meia-Idade , Compostos Organometálicos , Ácido Pentético/análogos & derivados
18.
J Magn Reson Imaging ; 7(1): 209-14, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-9039617

RESUMO

The purpose of the study was to investigate the use of a dextran-coated ultrasmall superparamagnetic iron oxide (USPIO) as a blood pool contrast agent for thoracic and abdominal MR angiography. Abdominal and thoracic MR angiography was performed in six healthy volunteers using two-dimensional and three-dimensional spoiled gradient echo (SPGR) sequences before and after intravenous administration of USPIO. Doses ranged from 1.1 to 2.6 mg Fe/kg. Flip angle was varied from 20 to 60 degrees. Subjective image quality, analysis of signal-to-noise ratio (SNR), and blood T1 relaxation times were measured. USPIO significantly lowered the T1 of blood (from 1,210 ms precontrast to 159 ms postcontrast at a dose of 2.6 mg Fe/kg) (P < .01). Image quality on coronal fast three-dimensional breath-hold SPGR images of the abdomen increased with increasing dose and was maximum at the highest dose, producing an aortic SNR of 9.6 compared to 1.8 precontrast. Axial two-dimensional time-of-flight (TOF) aortic SNR was reduced significantly from 13 on precontrast to 6 on the postcontrast images at the highest dose (P < .05) due to T2* shortening effects. There was little flip angle dependence on image quality. Due to the T1 shortening effect and long intravascular half-life, USPIO improved visualization of vascular anatomy using three-dimensional fast SPGR imaging. The echo time must be minimized to minimize signal loss from T2* shortening effects. The blood pool distribution of USPIO is useful for equilibrium-phase MR angiography.


Assuntos
Abdome/irrigação sanguínea , Compostos Férricos , Angiografia por Ressonância Magnética/métodos , Tórax/irrigação sanguínea , Adulto , Angiografia , Meios de Contraste , Relação Dose-Resposta a Droga , Estudos de Viabilidade , Feminino , Compostos Férricos/administração & dosagem , Compostos Férricos/farmacocinética , Meia-Vida , Humanos , Injeções Intravenosas , Masculino , Pessoa de Meia-Idade , Flebografia , Valores de Referência , Sensibilidade e Especificidade
19.
AJR Am J Roentgenol ; 168(1): 261-6, 1997 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8976957

RESUMO

OBJECTIVE: Our aim was to evaluate the effect of gadolinium chelates on image quality in phase-contrast MR angiography of renal arteries in patients suspected of having renal artery stenosis. MATERIALS AND METHODS: In 24 patients, axial three-dimensional phase-contrast MR angiography of the renal arteries was obtained on a 1.5-T MR imaging system before and after administration of gadolinium contrast agent. The improvement in distal renal artery signal-to-noise ratio after enhancement was measured and correlated with patient age, serum creatinine level, clinical estimation of renal artery flow, and the imaging parameter flip angle. RESULTS: On average, the distal renal artery signal-to-noise ratio increased 2.2-fold after gadolinium administration (p < .001). The increase was greatest in patients more than 60 years old (3.1-fold; p < .001) and in patients with serum creatinine levels greater than 3.0 mg/dl (4.3-fold; p < .01). After enhancement, we found an apparent increase in renal artery diameter (3.5 +/- 1.1 mm before enhancement versus 4.8 +/- 1.4 mm after enhancement [mean +/- SD; p < .001]). We believe this increase reflects improved visualization of slow blood flow along the artery wall. Although the visualization of renal arteries was better in most patients after enhancement, two patients had poorer image quality after enhancement because of increased venous signal obscuring the arteries. CONCLUSION: Gadolinium administration significantly increases distal renal artery signal-to-noise ratio on three-dimensional phase-contrast MR angiography in most patients. The signal-to-noise ratio improvement is greatest in older patients and in patients with impaired renal function. However, in some cases, increased venous signal may obscure arteries.


Assuntos
Meios de Contraste , Gadolínio , Angiografia por Ressonância Magnética/métodos , Obstrução da Artéria Renal/diagnóstico , Artéria Renal/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Aneurisma da Aorta Abdominal/diagnóstico , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos
20.
J Magn Reson Imaging ; 6(4): 642-51, 1996.
Artigo em Inglês | MEDLINE | ID: mdl-8835958

RESUMO

The optimum infusion timing and k-space ordering for obtaining gadolinium-enhanced three-dimensional MR angiograms was determined through computer modeling using temporal contrast characteristics obtained from patient gadolinium infusion data. The effects of bolus timing were evaluated by varying the relationship between peak intravascular gadolinium concentration and the time at which the center of k space was acquired (tck) for sequential and centric acquisition techniques. Flow phantom experiments were performed to validate the theoretical computations. Gadolinium concentration at the time of central k-space acquisition determines intravascular signal intensity. Artifacts, including vessel broadening and edge ringing, depend on the order in which k space is collected and on how rapidly the gadolinium concentration changes. Artifacts are greatest when the center of k space is acquired before the intravascular gadolinium peak. Application of the optimal infusion timing results in preferential arterial enhancement with a minimum of artifacts in patients undergoing MR angiography.


Assuntos
Meios de Contraste/administração & dosagem , Gadolínio , Aumento da Imagem/métodos , Angiografia por Ressonância Magnética/métodos , Algoritmos , Artefatos , Vasos Sanguíneos/patologia , Simulação por Computador , Combinação de Medicamentos , Análise de Fourier , Gadolínio/administração & dosagem , Gadolínio DTPA , Humanos , Processamento de Imagem Assistida por Computador , Infusões Intravenosas , Meglumina/administração & dosagem , Modelos Cardiovasculares , Compostos Organometálicos/administração & dosagem , Ácido Pentético/administração & dosagem , Ácido Pentético/análogos & derivados , Imagens de Fantasmas , Reprodutibilidade dos Testes , Fatores de Tempo
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