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1.
Drug Deliv ; 28(1): 733-740, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33827326

RESUMO

Talcum powder is recognized as the leading drug for pleurodesis, a treatment of choice for malignant pleural effusions. Recently, it was shown that hydrogel foam delivery systems significantly enhanced the number of adhesions between the chest wall and the lung in a New Zealand rabbit model due to the sol-gel transition. However, many questions still remain regarding the cause of improved efficacy, such as: (1) Would only hydrogel foams improve the efficacy of talc pleurodesis? (2) Is it possible to achieve the same efficacy of hydrogels using non-hydrogel foams? 3) What are the physicochemical properties that can be correlated to the efficacy of talc pleurodesis? In this study, we use non-hydrogel foam formulations to determine the efficacy of pleurodesis. Foam stability and rheology of the formulations were correlated to adhesion formation. The results clearly suggest a correlation of pleurodesis efficacy to the viscosity and modulus of the foam delivery system.


Assuntos
Hidrogéis/química , Pleurodese/métodos , Talco/administração & dosagem , Animais , Química Farmacêutica , Estabilidade de Medicamentos , Coelhos , Reologia , Talco/uso terapêutico
2.
AJNR Am J Neuroradiol ; 29(10): 1847-54, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18768727

RESUMO

BACKGROUND AND PURPOSE: Time-resolved MR angiography (MRA) offers the combined advantage of large anatomic coverage and hemodynamic flow information. We applied parallel imaging and time-resolved imaging with stochastic trajectories (TWIST), which uses a spiral trajectory to undersample k-space, to perform time-resolved MRA of the extracranial internal carotid arteries and compare it to time-of-flight (TOF) and high-resolution contrast-enhanced (HR) MRA. MATERIALS AND METHODS: A retrospective review of 31 patients who underwent carotid MRA at 1.5T using TOF, time-resolved and HR MRA was performed. Images were evaluated for the presence and degree of ICA stenosis, reader confidence, and number of pure arterial frames attained with the TWIST technique. RESULTS: With a consensus interpretation of all sequences as the reference standard, accuracy for identifying stenosis was 90.3% for TWIST MRA, compared with 96.0% and 88.7% for HR MRA and TOF MRA, respectively. HR MRA was significantly more accurate than the other techniques (P < .05). TWIST MRA yielded datasets with high in-plane spatial resolution and distinct arterial and venous phases. It provided dynamic information not otherwise available. Mean diagnostic confidence was satisfactory or greater for TWIST in all patients. CONCLUSION: The TWIST technique consistently obtained pure arterial phase images while providing dynamic information. It is rapid, uses a low dose of contrast, and may be useful in specific circumstances, such as in the acute stroke setting. However, it does not yet have spatial resolution comparable with standard contrast-enhanced MRA.


Assuntos
Artérias Carótidas/patologia , Doenças das Artérias Carótidas/patologia , Gadolínio DTPA , Aumento da Imagem/métodos , Imageamento Tridimensional/métodos , Angiografia por Ressonância Magnética/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Meios de Contraste , Feminino , Gadolínio DTPA/administração & dosagem , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Processos Estocásticos
3.
AJNR Am J Neuroradiol ; 27(10): 2118-21, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-17110679

RESUMO

The combination of 3T and parallel-acquisition techniques holds promise for improved performance of contrast-enhanced MR angiography (MRA), in terms of speed, spatial resolution, and coverage. We present a comparison of 2 MRA techniques, including time-of-flight (TOF) and contrast-enhanced MRA, for detection and evaluation of intracranial aneurysms. Our results show that contrast-enhanced MRA with highly accelerated parallel acquisition at 3T does not have the known drawbacks of TOF-MRA techniques, including prolonged acquisition time, spin saturation, and flow-related artifacts, with comparable aneurysm characterization.


Assuntos
Meios de Contraste , Aneurisma Intracraniano/diagnóstico , Angiografia por Ressonância Magnética/métodos , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
4.
Rofo ; 178(5): 515-24, 2006 May.
Artigo em Alemão | MEDLINE | ID: mdl-16586309

RESUMO

PURPOSE: The aim of this study was the optimization of a gradient echo (GRE) MR tagging sequence at 3.0 T in comparison to 1.5 T in order to obtain the best image contrast between the myocardium, tag lines and blood signal. Theoretically expected improvements of signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were also calculated. MATERIALS AND METHODS: 14 healthy volunteers (8 male, 6 female; mean age 43.4 +/- 10.3 years) were scanned using a 3.0 T as well as a 1.5 T whole-body system. A GRE flash-2 D tagging sequence was evaluated (midventricular short axis view) by varying the flip angle (8 - 16 degrees ), slice thickness (4 - 8 mm; fixed flip angle 1.5/3.0 T: 12 degrees /8 degrees , tag size 8 mm) and tag size (4 - 8 mm, fixed flip angle 1.5/3.0 T: 12 degrees /8 degrees , slice thickness 6 mm). The field of view, acquisition time and temporal resolution (45 ms) were kept constant. Qualitative and quantitative image analysis was performed by calculating the SNR, CNR (tag) as well as the relative contrast between the myocardium and tag lines (RCMT). RESULTS: Based on individual comparison, the best imaging protocol was found at a slice thickness of 6 mm, tag size of 8 mm, optimized flip angle of 8 degrees (3.0 T) and 12 degrees (1.5 T), respectively. Compared to 1.5 T, a significantly higher overall image score was determined (mean +/- sd; 3.2 +/- 0.2 vs. 2.7 +/- 0.4) and a strong correlation between the CNR (tag) and RCMT for flip angle alpha and the slice thickness was found. A higher field strength resulted in an 80 % increase in the CNR (tag) compared to 1.5 T (mean 10.7/6.1). Furthermore, the SNR was improved by 35 % (mean 20.6/15.3) and the RCMT by 35 % (mean 0.47/0.35). CONCLUSION: Myocardial tagging at 3.0 T has shown superior image quality in comparison to 1.5 T due to a higher baseline SNR and an improved CNR as well as RCMT. The suppressed fading of the tags enables the accessibility to the diastolic phase of the cardiac cycle.


Assuntos
Coração/anatomia & histologia , Coração/fisiologia , Imageamento por Ressonância Magnética/métodos , Adulto , Interpretação Estatística de Dados , Feminino , Humanos , Imageamento por Ressonância Magnética/instrumentação , Masculino , Pessoa de Meia-Idade , Contração Miocárdica , Sensibilidade e Especificidade , Sístole
5.
Rofo ; 177(6): 800-4, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15902628

RESUMO

PURPOSE: To evaluate the feasibility of high-spatial resolution magnetic resonance angiography (MRA) of the renal arteries at 3.0 T. MATERIAL AND METHODS: Twelve healthy volunteers (mean age, 38.8 years) underwent renal MRA at 3.0 T. The application of parallel imaging with an acceleration factor of 3 allowed obtaining MR angiographic data with a voxel size of 0.9 x 0.8 x 0.9 mm in scan time of only 16 s. A dose of 0.2 mmol/kg body weight of 0.5-molar gadodiamide was administered at a flow rate of 2 ml/s. For image analysis, image quality, presence of artifacts, venous contamination and level of noise were rated by two radiologists in consensus. RESULTS: All examinations were of diagnostic quality. The image quality was rated good or very good in 91 % (11/12) of cases. Due to the high parallel imaging factor the level of noise was slightly increased without diagnostic impairment. Mild venous enhancement was found in 75 % (9/12) of the examinations. CONCLUSION: Renal MRA at 3.0 T is feasible with high spatial resolution and a short acquisition time.


Assuntos
Rim/irrigação sanguínea , Angiografia por Ressonância Magnética , Artéria Renal/anatomia & histologia , Adulto , Idoso , Algoritmos , Artefatos , Estudos de Viabilidade , Feminino , Humanos , Consentimento Livre e Esclarecido , Angiografia por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Imagens de Fantasmas
6.
Radiologe ; 44(10): 975-84, 2004 Oct.
Artigo em Alemão | MEDLINE | ID: mdl-15549221

RESUMO

Arteriosclerosis of the supra-aortic vessels is a known risk factor for cerebrovascular disease. Large multicenter studies like NASCET and ECST have proven the protective effects of the surgical treatment of severe (>70%) carotid artery stenoses. The exact detection and grading of stenoses of the carotid arteries is a prerequisite for a successful therapy. Besides the gold-standard examination, digital subtraction angiography (DSA), MR angiography (MRA) is being used increasingly. MRA allows a non-invasive, high-resolution depiction of the supra-aortic vessels without ionizing radiation in only 20 s. This article first illustrates the MRA-techniques, and the indications and limitations of MRA. Next, the diagnostic accuracy of MRA is compared to DSA and ultrasound. The clinical value of MRA for the detection of stenoses of the carotid arteries is discussed on the basis of clinical examples.


Assuntos
Estenose das Carótidas/diagnóstico , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional , Arteriosclerose Intracraniana/diagnóstico , Angiografia por Ressonância Magnética , Angiografia Digital , Artéria Carótida Interna/patologia , Dissecação da Artéria Carótida Interna/diagnóstico , Angiografia Cerebral , Humanos , Sensibilidade e Especificidade , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/prevenção & controle
7.
Rofo ; 175(6): 822-9, 2003 Jun.
Artigo em Alemão | MEDLINE | ID: mdl-12811696

RESUMO

AIM: To investigate the signal-enhancing effects of the macromolecular contrast medium Gadomer in MR angiography of the coronary arteries compared to Gd-DTPA. MATERIAL AND METHODS: A total of 15 MRI examinations of the heart were performed in pigs at 1.5 T using a pulse-triggered, segmented 3D FLASH sequence with data acquisition during breathhold before and up to 30 min after contrast medium injection. Gadomer was investigated at two doses (0.05 and 0.1 mmol Gd/kg), Gd-DTPA at one (0.3 mmol Gd/kg) (n = 5 examinations per dose). Standard sequences without magnetization preparation were supplemented by sequences with magnetization saturation applied before data acquisition before and immediately after contrast medium injection. Analysis comprised quantitative determination of blood and myocardium signal to noise (S/N) and contrast to noise (C/N) and qualitative assessment of several parameters of image quality and coronary artery visualization. RESULTS: Gadomer leads to a significant C/N increase between blood and myocardium compared to the unenhanced examination and the increase is longer-lasting than that produced by Gd-DTPA (Gd-DTPA: only directly after injection; Gadomer: up to 5 min post injection at 0.05 mmol Gd/kg, up to 10 min at 0.1 mmol Gd/kg). The qualitative evaluation shows that visualization of the coronary arteries and branch vessels is significantly better with Gadomer at both doses than with Gd-DTPA. Magnetization saturation increases the C/N in combination with Gd-DTPA and at the higher dose of Gadomer with the latter producing a higher increase in C/N values. CONCLUSION: Gadomer is a suitable contrast medium for MR angiography of the coronary arteries with the dose of 0.1 mmol Gd/kg being superior to 0.05 mmol Gd/kg due to a longer imaging window.


Assuntos
Meios de Contraste/administração & dosagem , Doença das Coronárias/diagnóstico , Vasos Coronários/patologia , Gadolínio DTPA , Gadolínio , Angiografia por Ressonância Magnética/métodos , Animais , Artefatos , Meios de Contraste/farmacocinética , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Gadolínio/farmacocinética , Gadolínio DTPA/farmacocinética , Injeções Intravenosas , Taxa de Depuração Metabólica/fisiologia , Sensibilidade e Especificidade , Suínos , Porco Miniatura
8.
Radiology ; 221(3): 827-36, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11719686

RESUMO

The authors developed and evaluated two cine magnetic resonance (MR) imaging sequences with a radial rather than a rectilinear k-space coordinate frame: segmented k space and real-time true fast imaging with steady-state precession, or FISP. The two radial k-space segmentation (or view sharing) techniques, which were interleaved or continuous, were compared, and the feasibility of their application in cardiac cine MR imaging was explored in phantom and volunteer studies. Images obtained with the radial sequences were compared with those obtained with two-dimensional Fourier transform, or 2DFT, sequences currently used in cine MR imaging. Temporal resolution of 55 msec was achieved with the real-time radial sequences, which allowed acquisition of almost 19 high-quality images per second.


Assuntos
Imagem Cinética por Ressonância Magnética/métodos , Contração Miocárdica , Adulto , Humanos , Aumento da Imagem/métodos , Masculino , Pessoa de Meia-Idade , Imagens de Fantasmas
9.
J Magn Reson Imaging ; 14(4): 348-54, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11599057

RESUMO

Contrast-enhanced coronary angiography has become an important technique for magnetic resonance (MR) coronary artery imaging. However, the relationship between the quality of the coronary artery images and blood T1 has not yet been fully explored. In this paper, we assessed this relationship in an animal model by using a prototypical blood pool agent. With accumulated injections of this agent, the blood T1 would be maintained at different levels. The measured blood T1 values in vivo were 147 +/- 3, 82 +/- 6, 48 +/- 4, 40 +/- 3, and 30 +/- 8 msec (N = 7). Fixed and variable flip angle schemes were used in coronary artery imaging. The signal to noise ratios (SNR) of coronary arteries were measured and the image quality was assessed. It was found that blood T1 less than 80 msec might be desired. No statistically significant difference was observed between two flip angle schemes. There was better vessel definition using variable flip angle at blood T1 lower than 50 msec. Understanding this relationship may be beneficial to optimizing image protocol and/or design of blood pool contrast agents for contrast-enhanced coronary angiography.


Assuntos
Angiografia Coronária/métodos , Angiografia por Ressonância Magnética/métodos , Animais , Simulação por Computador , Suínos
10.
J Magn Reson Imaging ; 14(4): 425-32, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11599067

RESUMO

Initial evaluation of a new blood pool agent, B-22956/1, for pulmonary imaging was performed in five domestic pigs with artificial embolism. Pre-embolism 3D pulmonary perfusion images were first acquired by injecting an extravascular agent, gadoteridol. The pulmonary arteries of the pigs were then occluded by the artificial emboli. Post-embolism perfusion scans were subsequently performed by injecting B-22956/1. Additional post-embolism high-spatial-resolution angiograms were also acquired. Parenchyma perfusion deficits were well depicted in the post-embolism perfusion maps. The post-embolism angiography clearly revealed the location and extent of the filling defects in the pulmonary vessels. Signal intensities of perfusion maps on the normal parenchyma were significantly improved (30%) by using B-22956/1, in comparison with perfusion images using gadoteridol (P < 0.01). Many pulmonary angiograms with approximately equal contrast could be obtained even at 22 minutes after the injection of B-22956/1. Our initial results indicate that blood pool agent B-22956/1 may provide opportunities for whole-lung-coverage perfusion mapping and additional high-resolution target angiograms after a single injection.


Assuntos
Meios de Contraste , Pulmão/anatomia & histologia , Angiografia por Ressonância Magnética/métodos , Imageamento por Ressonância Magnética/métodos , Compostos Organometálicos , Circulação Pulmonar/fisiologia , Animais , Gadolínio , Compostos Heterocíclicos , Pulmão/fisiologia , Embolia Pulmonar/diagnóstico , Suínos
11.
J Magn Reson Imaging ; 14(3): 319-28, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11536410

RESUMO

The purpose of this study was to develop a method for reducing gadolinium dose and suppressing venous overlap in moving-table three-dimensional (3D) magnetic resonance (MR) angiography from the abdomen to the feet. Thirty-one patients underwent three-phase infusion of 16-18 mL of gadolinium: infusion rates and imaging times were determined after taking into account mean blood flow velocity, so that image acquisition was synchronized with peak arterial enhancement at both the first and third stations (velocity-dependent method). Twenty-three other patients underwent slow infusion of 38 mL of gadolinium with fixed acquisition time (high-dose method). The image quality for the two methods was compared. The velocity-dependent method produced good image quality with significantly less venous overlap than the high-dose method, especially in the below-the-knee region (P <.001). The velocity-dependent method provides satisfactory MR angiograms using 16-18 mL of gadolinium in patients having various blood flow velocities.


Assuntos
Artérias/patologia , Meios de Contraste/administração & dosagem , Gadolínio/administração & dosagem , Angiografia por Ressonância Magnética/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Velocidade do Fluxo Sanguíneo , Constrição Patológica/diagnóstico , Feminino , Humanos , Aumento da Imagem , Imageamento Tridimensional , Perna (Membro)/irrigação sanguínea , Masculino , Pessoa de Meia-Idade , Modelos Biológicos
12.
Magn Reson Med ; 46(3): 494-502, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11550241

RESUMO

The purpose of this work was to develop an ECG-triggered, segmented 3D true-FISP (fast imaging with steady-state precession) technique to improve the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of breath-hold coronary artery imaging. The major task was to optimize an appropriate magnetization preparation scheme to permit saturation of the epicardial fat signal. An alpha/2 preparation pulse was used to speed up the approach to steady-state following a frequency-selective fat-saturation pulse in each heartbeat. The application of dummy cycles was found to reduce the oscillation of the magnetization during data acquisition. The fat saturation and magnetization preparation scheme was validated with simulations and phantom studies. Volunteer studies demonstrated substantially increased SNR (55%) and CNR (178%) for coronary arteries compared to FLASH (fast low-angle shot) with the same imaging time. In conclusion, true-FISP is a promising technique for coronary artery imaging.


Assuntos
Vasos Coronários/anatomia & histologia , Aumento da Imagem , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional , Angiografia por Ressonância Magnética , Adulto , Eletrocardiografia , Feminino , Humanos , Masculino , Imagens de Fantasmas , Valores de Referência , Sensibilidade e Especificidade
13.
Eur Radiol ; 11(8): 1355-63, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11519543

RESUMO

The aim of this study was to test three injection protocols for contrast-enhanced magnetic resonance angiography (MRA) of the thoracic aorta with a standard-dose application. Ninety-three patients with a total of 118 examinations underwent MRA of the thoracic aorta at 1.5 T. There were three injection protocols: in 24 cases, no test bolus was performed and contrast was injected manually; in 14 cases, contrast was injected manually after a test bolus; and in 80 cases, a MR-compatible injector was used after a timing examination. All patients received 20 ml of Gd-DTPA. Quantitative signal-to-noise (SNR) measurements were obtained at different locations in the thoracic aorta, the pulmonary arteries, and the superior vena cava. Two readers in conference retrospectively evaluated each examination with respect to overall image quality and quality of bolus timing. Bolus timing was considered optimal in 70 cases, and either too early or too late in 11 cases. In 37 examinations the bolus was broadened. The SNR measurements of the thoracic aorta revealed that examinations after bolus testing were significantly superior to examinations without a test bolus (p < 0.001). Signal intensity ratios of the aorta and the pulmonary trunk were significantly higher in examinations with an optimal contrast timing (p < 0.001). Magnetic resonance angiograms of the thoracic aorta with a timing run are significantly superior to non-timed examinations with respect to image quality and SNRs. The administration of 20 ml of Gd-DTPA is sufficient for adult patients.


Assuntos
Aorta Torácica/patologia , Meios de Contraste/administração & dosagem , Gadolínio DTPA , Angiografia por Ressonância Magnética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Doenças da Aorta/diagnóstico , Feminino , Gadolínio DTPA/administração & dosagem , Humanos , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional , Injeções Intravenosas/instrumentação , Injeções Intravenosas/métodos , Masculino , Pessoa de Meia-Idade
14.
Radiology ; 220(2): 540-7, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11477266

RESUMO

Selective line acquisition mode (SLAM) reduces magnetic resonance imaging time by a factor n relative to conventional techniques. Seventeen patients with cardiac disease and three volunteers were examined with SLAM and two-frame interpolation (2FI). SLAM images were sharper than 2FI images and showed well-defined endocardial borders. SLAM is best suited for fast imaging of moving objects, such as the heart, confined to 1/n of the field of view.


Assuntos
Coração/anatomia & histologia , Imageamento por Ressonância Magnética/métodos , Adulto , Idoso , Artefatos , Feminino , Cardiopatias/diagnóstico , Humanos , Masculino , Pessoa de Meia-Idade , Sensibilidade e Especificidade
15.
Radiology ; 220(1): 252-6, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11426006

RESUMO

A technique for whole-body magnetic resonance (MR) imaging in only 30 seconds was developed on the basis of a rolling table platform with integrated surface coils and real-time true fast imaging with steady-state precession. In five patients, all hepatic and pulmonary lesions with a diameter exceeding 8 mm were detected by using thoracic and abdominal helical computed tomography as the reference method. Whole-body MR imaging with real-time true fast imaging with steady-state precession is feasible and may be suitable for tumor screening and staging.


Assuntos
Neoplasias Brônquicas/diagnóstico , Imageamento por Ressonância Magnética/métodos , Neoplasias Ovarianas/diagnóstico , Neoplasias Testiculares/diagnóstico , Adulto , Idoso , Desenho de Equipamento , Estudos de Viabilidade , Feminino , Humanos , Imageamento por Ressonância Magnética/instrumentação , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Valores de Referência , Sensibilidade e Especificidade , Fatores de Tempo
16.
J Magn Reson Imaging ; 13(3): 372-7, 2001 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11241809

RESUMO

Although 3D MRA has been shown to provide excellent depiction of the pulmonary arterial tree, its clinical use has been limited due to lengthy breath-holding requirements. Employing the newest gradient generation (1.5 T MR system, amplitude of 40 mT/m and a slew rate of 200 mT/m/msec), we evaluated a technique permitting the dynamic acquisition of 3D data sets of the entire pulmonary tree in under 4 seconds. Coronal image sets were collected using a repetition time of 1.64 msec and an echo time of 0.6 msec, resulting in an acquisition time of 3.74 seconds. Three volunteers and eight dyspneic patients with known or suspected pulmonary embolism underwent MRI of the pulmonary arteries. The pulmonary arterial tree was visible to a subsegmental level in all examined subjects. Regarding the presence of pulmonary emboli in four patients, there was complete concordance between MR angiographic findings and those of corroborative studies. We conclude that diagnostic MRA of the pulmonary vasculature can be obtained even in patients with severe respiratory distress.


Assuntos
Aumento da Imagem , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional , Angiografia por Ressonância Magnética , Artéria Pulmonar/patologia , Dispneia/etiologia , Eficiência , Humanos , Embolia Pulmonar/diagnóstico , Sensibilidade e Especificidade , Fatores de Tempo
17.
Radiology ; 219(1): 264-9, 2001 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11274568

RESUMO

Short- and long-axis cine magnetic resonance (MR) images were obtained with a standard fast low-angle shot, or FLASH, sequence and a first-generation true fast imaging with steady-state precession (FISP) sequence on a 1.5-T MR imager. Contrast-to-noise ratios and volumetric left ventricular measurements were compared for manual and automatic segmentation. True FISP images were associated with significantly (P<.01) higher contrast-to-noise ratios and allowed better detection of the endocardial border. True FISP images were provided with short acquisition times and excellent contrast between the myocardium and the ventricular lumen.


Assuntos
Doença das Coronárias/diagnóstico , Insuficiência Cardíaca/diagnóstico , Aumento da Imagem , Processamento de Imagem Assistida por Computador , Imagem Cinética por Ressonância Magnética/métodos , Função Ventricular Esquerda/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Doença das Coronárias/fisiopatologia , Diástole/fisiologia , Feminino , Insuficiência Cardíaca/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Sensibilidade e Especificidade , Volume Sistólico/fisiologia , Sístole/fisiologia
18.
J Magn Reson Imaging ; 13(2): 301-7, 2001 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11169838

RESUMO

The purpose of this work was to develop a multiple-breath-hold (BH) imaging method for coronary arteries in which a segment of k-space is acquired in each BH. The goal was to increase the resolution, or the signal-to-noise ratio (SNR) and coverage, of three-dimensional-(3D)-BH volume-targeted scanning (VCATS). To correct for slab position differences, a real-time slab following technique using navigator echoes for motion detection was used. Sixteen normal volunteers were imaged to compare the method with a single-BH scan. Results showed that higher resolution, or larger coverage and higher SNR, were achieved by the multiple-BH method without respiratory motion artifacts. In conclusion, 3D segmented k-space data acquisition with multiple-BHs and real-time slab following is a promising approach for extending the capabilities of VCATS further.


Assuntos
Vasos Coronários/patologia , Aumento da Imagem , Imageamento Tridimensional , Angiografia por Ressonância Magnética/métodos , Imageamento por Ressonância Magnética/métodos , Adulto , Doença das Coronárias/diagnóstico , Humanos , Processamento de Imagem Assistida por Computador , Valores de Referência
19.
J Magn Reson Imaging ; 12(6): 912-23, 2000 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11105030

RESUMO

The authors describe the optimization of a contrast-enhanced, breath-held, three-dimensional magnetic resonance angiography (CE-BH-3DMRA) technique in the assessment of the renal arteries and compare its utility with conventional x-ray angiography (XRA). Signal optimization using specific pulse sequence parameters was based on the patient's circulatory conditions, injection rate, and pulse sequence timing. Fifty-one patients (27 M, 24 F; mean age 69.7 years) were evaluated with CE-BH-3DMRA and XRA. All patients had an MR angiogram 3 months either before or after XRA. A test bolus study was performed for accurate assessment of transit time in each patient. A total of 51 patients (115 vessels) were studied in which the sensitivity and specificity for all renal artery stenoses including the proximal and mid-renal arterial segments were 96% and 92%, respectively. In-stent stenosis could only be diagnosed by quantifying flow beyond the stent using an additional triggered phase contrast cine pulse sequence. A total of 11 accessory renal arteries were correctly identified. In addition, fibromuscular dysplasia in two patients and stents in three patients were correctly identified on MRA. J. Magn. Reson. Imaging 2000;12:912-923.


Assuntos
Imageamento Tridimensional , Angiografia por Ressonância Magnética/métodos , Obstrução da Artéria Renal/diagnóstico , Adulto , Idoso , Idoso de 80 Anos ou mais , Velocidade do Fluxo Sanguíneo/fisiologia , Feminino , Displasia Fibromuscular/diagnóstico , Displasia Fibromuscular/terapia , Oclusão de Enxerto Vascular/diagnóstico , Humanos , Masculino , Pessoa de Meia-Idade , Artéria Renal/patologia , Obstrução da Artéria Renal/terapia , Sensibilidade e Especificidade , Stents
20.
J Am Coll Cardiol ; 36(1): 44-50, 2000 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-10898411

RESUMO

OBJECTIVES: The purpose of this study was to evaluate a contrast-enhanced three-dimensional (3D) breath-hold magnetic resonance (MR) technique for detection of coronary artery stenoses. BACKGROUND: The accuracy of previously published MR coronary angiography protocols varies widely. Recently, coronary artery imaging using T1-shortening contrast agent has become possible, but so far there are no data concerning its clinical application. METHODS: Magnetic resonance coronary angiography was performed in 50 patients with suspected coronary artery disease. Magnetic resonance data acquisition using an ultrafast 3D gradient-echo sequence lasted over 32 heartbeats within one single breath-hold. Twenty milliliters of gadopentetate dimeglumine was injected at a flow rate of 1 ml/s for two successive studies covering the main coronary arteries in single-oblique planes. Stenosis assessment by MR was compared with significant (diameter stenosis > 50%) stenoses on X-ray angiography. Evaluation was limited to the proximal and mid-coronary artery segments. RESULTS: Two hundred sixty-eight of 350 artery segments (76.6%) could be evaluated. Left circumflex coronary artery was only evaluable in 50% of cases by MR. In the evaluable segments, 48 of 56 stenoses and 193 of 212 nonstenotic segments were correctly classified by MR. On a patient basis, MR correctly identified 34 of 36 patients with and 8 of 14 patients without significant coronary stenoses as demonstrated by X-ray angiography (sensitivity 94.4%, specificity 57.1%). CONCLUSIONS: Oblique projection contrast-enhanced MR coronary angiograms obtained within one single breath-hold permit identification of patients with coronary stenoses in the proximal and mid segments of the major coronary arteries with satisfactory accuracy.


Assuntos
Doença das Coronárias/diagnóstico , Vasos Coronários/patologia , Processamento de Imagem Assistida por Computador , Angiografia por Ressonância Magnética , Adulto , Idoso , Meios de Contraste/administração & dosagem , Angiografia Coronária , Feminino , Gadolínio DTPA/administração & dosagem , Humanos , Injeções Intravenosas , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
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