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1.
Magn Reson Med ; 48(3): 419-24, 2002 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-12210905

RESUMEN

Fast arterial-venous transit in the carotid arteries requires accurate, reliable timing of the acquisition to the bolus transit to maximize arterial signal and minimize venous artifacts. The rising edge of the bolus is not utilized in conventional elliptical-centric view-ordering because the critical k-space center must be acquired with full arterial enhancement. In this study, a recessed elliptical-centric view-ordering scheme is introduced in which the k-space center is acquired a few seconds following scan initiation. The recessed view-ordering is shown to be more robust to timing errors than the conventional scheme in a study of 37 patients.


Asunto(s)
Enfermedades de las Arterias Carótidas/diagnóstico , Imagenología Tridimensional , Angiografía por Resonancia Magnética/métodos , Medios de Contraste , Fluoroscopía , Gadolinio DTPA , Humanos
2.
Invest Radiol ; 36(7): 422-9, 2001 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-11496097

RESUMEN

RATIONALE AND OBJECTIVES: The purpose of this study was to identify the cross-sectional location of collateral vessels in patients with peripheral vascular disease on three-dimensional magnetic resonance angiograms (3D MRAs) to suggest sites for intravascular or transcutaneous angiogenesis gene delivery in the lower extremity. METHODS: The axial locations were measured and categorized by tissue compartments, as well as by radial coordinates with respect to the femur. RESULTS: Collateral vessels in the thigh were identified in 24 of 93 consecutive patients who underwent peripheral 3D MRA. Ninety-one percent (99/109) of the observed collaterals were located near the adductor canal level of the thigh, with 78% (31/46) of these collaterals located in the fat in or surrounding the posterior muscle. CONCLUSIONS: The majority of collateral vessels in the thigh are located in the fat or muscle within the posterior compartment near the femur at the level of the adductor canal.


Asunto(s)
Arteriopatías Oclusivas/patología , Circulación Colateral , Arteria Femoral/patología , Muslo/irrigación sanguínea , Adulto , Anciano , Anciano de 80 o más Años , Arteriopatías Oclusivas/diagnóstico por imagen , Femenino , Arteria Femoral/diagnóstico por imagen , Humanos , Imagenología Tridimensional , Angiografía por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Arteria Poplítea/patología , Radiografía , Muslo/anatomía & histología , Muslo/diagnóstico por imagen
3.
J Vasc Surg ; 33(6): 1148-57, 2001 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-11389411

RESUMEN

INTRODUCTION: Intra-arterial thrombolysis is commonly used as the initial treatment of acute or subacute lower extremity ischemia. METHODS: To evaluate the efficacy and cost of thrombolysis, we retrospectively analyzed 100 consecutive cases (87 patients) in which intra-arterial lysis (urokinase) was used as the initial treatment for native arterial lower extremity occlusive disease. The mean age of patients was 67 years, 57% of the patients were male, and preexisting peripheral vascular disease was present in 74%. Presenting symptoms were limb-threatening ischemia (53%) and claudication (47%). Acute symptoms (< 2 weeks' duration) were present in 48%. RESULTS: The 30-day morbidity rate was 31%, and four patients died. Complications were significant bleeding (23%), ischemic stroke (1%), and renal failure with (2%) and without (2%) dialysis. Concomitant angioplasty was performed in 63%. Complete or significant lysis as demonstrated with angiography was achieved in 75% of iliac, 58% of femoropopliteal, and 41% of crural vessels (P <.001). Within 30 days of lysis, 9% of patients underwent major amputation and 20% surgical revascularization (in 3 patients the extent of revascularization was lessened by the lytic therapy). Amputation-free survival was 83% and 75% at 6 months and 2 years, respectively. Relief of ischemia (defined as relief of claudication or limb salvage without major surgical intervention) was achieved in only 70% and 43% of patients at 30 days and 2 years, respectively (Kaplan-Meier analysis; mean follow-up, 31 months). Patients with aortoiliac disease had significantly better outcomes than those with infrainguinal disease (P =.03). Duration or type of presenting symptoms did not predict outcome. The cost of the initial hospitalization per patient for thrombolysis was $18,490. CONCLUSION: Thrombolysis can be as or more costly than surgery and is associated with a suboptimal outcome in a significant number of patients. These data lead us to caution against a uniform policy of initial thrombolysis for patients who present with lower extremity ischemia.


Asunto(s)
Arteriopatías Oclusivas/tratamiento farmacológico , Fibrinolíticos/administración & dosificación , Costos de Hospital , Isquemia/tratamiento farmacológico , Pierna/irrigación sanguínea , Terapia Trombolítica/economía , Terapia Trombolítica/métodos , Activador de Plasminógeno de Tipo Uroquinasa/administración & dosificación , Anciano , Anciano de 80 o más Años , Análisis de Varianza , Angiografía , Arteriopatías Oclusivas/diagnóstico por imagen , Arteriopatías Oclusivas/mortalidad , Análisis Costo-Beneficio , Femenino , Arteria Femoral/diagnóstico por imagen , Arteria Femoral/efectos de los fármacos , Humanos , Claudicación Intermitente , Isquemia/diagnóstico por imagen , Isquemia/mortalidad , Masculino , Persona de Mediana Edad , Enfermedades Vasculares Periféricas/diagnóstico por imagen , Enfermedades Vasculares Periféricas/tratamiento farmacológico , Enfermedades Vasculares Periféricas/mortalidad , Valor Predictivo de las Pruebas , Probabilidad , Modelos de Riesgos Proporcionales , Estudios Retrospectivos , Índice de Severidad de la Enfermedad , Tasa de Supervivencia , Resultado del Tratamiento
4.
Invest Radiol ; 36(3): 170-7, 2001 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-11228581

RESUMEN

UNLABELLED: Wang Y, Winchester PA, Khilnani NM, et al. Contrast-enhanced peripheral MR angiography from the abdominal aorta to the pedal arteries: Combined dynamic two-dimensional and bolus-chase three-dimensional acquisitions. Invest Radiol 2001;36:170-177. RATIONALE AND OBJECTIVES: To obtain reliable contrast-enhanced peripheral MR angiography for imaging peripheral vascular disease from the abdominal aorta to the pedal arteries. METHODS: A protocol consisting of contrast-enhanced, dynamic two-dimensional (2D) acquisition at the feet and calf and bolus-chase three-dimensional (3D) acquisition from the abdominal aorta to the calf was developed and applied in patients with peripheral vascular disease. The performance of this integrated protocol was assessed in 89 consecutive patients. RESULTS: The bolus-chase 3D acquisition was of diagnostic quality in 100% of the acquisitions in the abdomen, 96% in the thigh, and 43% in the calf. The poor quality of the calf acquisitions was due to insufficient spatial resolution, poor arterial signal, and venous contamination. Diagnostic-quality images were obtained in 100% of the dynamic 2D acquisitions of the calf and 98% of the feet. CONCLUSIONS: The combined dynamic 2D and bolus-chase 3D contrast-enhanced MR angiography technique provides diagnostic images of the entire lower extremity.


Asunto(s)
Aorta Abdominal/diagnóstico por imagen , Medios de Contraste , Pie/irrigación sanguínea , Pie/diagnóstico por imagen , Angiografía por Resonancia Magnética/métodos , Adulto , Anciano , Anciano de 80 o más Años , Angiografía de Substracción Digital , Femenino , Humanos , Masculino , Persona de Mediana Edad
5.
Radiology ; 218(3): 899-904, 2001 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-11230673

RESUMEN

The purpose of this study was to evaluate a variable k-space sampling method for bolus-chase three-dimensional magnetic resonance digital subtraction angiography in the arterial system from the abdomen to the calf. Imaging time was minimized by tailoring the acquisition according to the vascular anatomy of the station. For images obtained in 30 patients, results with the modified protocol were compared to those with the previously published protocol. For all stations, significant improvement (P <.001) was found with the modified protocol.


Asunto(s)
Angiografía de Substracción Digital/métodos , Angiografía por Resonancia Magnética/métodos , Adulto , Anciano , Femenino , Humanos , Imagenología Tridimensional , Masculino , Persona de Mediana Edad
6.
Radiology ; 215(2): 600-7, 2000 May.
Artículo en Inglés | MEDLINE | ID: mdl-10796945

RESUMEN

A view order that matches k-space sampling to cardiac motion within the acquisition window was developed for breath-hold three-dimensional contrast material-enhanced coronary magnetic resonance angiography. In vivo experiments in seven volunteers demonstrated that blurring was substantially reduced with this motion-matched view order as compared with the standard centric view order. Coronary arteries were well delineated.


Asunto(s)
Medios de Contraste , Vasos Coronarios/anatomía & histología , Corazón/fisiología , Aumento de la Imagen/métodos , Procesamiento de Imagen Asistido por Computador/métodos , Angiografía por Resonancia Magnética/métodos , Respiración , Adulto , Algoritmos , Electrocardiografía , Estudios de Factibilidad , Femenino , Frecuencia Cardíaca/fisiología , Humanos , Masculino , Movimiento , Contracción Miocárdica/fisiología , Variaciones Dependientes del Observador
7.
J Vasc Interv Radiol ; 9(6): 891-9; discussion 900, 1998.
Artículo en Inglés | MEDLINE | ID: mdl-9840032

RESUMEN

PURPOSE: To perform a preliminary evaluation of the diagnostic accuracy of contrast-enhanced, two-dimensional (2D) magnetic resonance (MR) digital subtraction angiography (DSA) of the lower extremity by comparison with x-ray angiography (XRA). MATERIALS AND METHODS: Forty lower extremities in 22 patients were imaged at multiple levels with both XRA and 2D MR DSA. Images were retrospectively analyzed by three radiologists in a randomized blinded manner. Seventeen vascular segments were graded as an insignificant lesion, a significant lesion, or as an occlusion. With the use of segments well depicted with XRA as the gold standard, the sensitivity, specificity, and accuracy of 2D MR DSA, as compared with XRA, were evaluated. The McNemar-Stuart-Maxwell test was performed to determine the significance of any differences found. RESULTS: Three hundred eighty-three arterial segments were evaluated with both techniques. Three hundred one segments were well depicted with XRA. There was no significant difference between 2D MR DSA and XRA for assessing the degree of occlusive disease in these 301 segments (.25 < P < .5). The sensitivity, specificity, and diagnostic accuracy of 2D MR DSA were found to be 90%, 98%, and 93%, respectively. CONCLUSION: Two-dimensional MR DSA is an accurate method for assessing arterial lesions in the lower extremity.


Asunto(s)
Angiografía de Substracción Digital , Arteriopatías Oclusivas/diagnóstico , Pierna/irrigación sanguínea , Angiografía por Resonancia Magnética , Técnica de Sustracción , Adulto , Anciano , Anciano de 80 o más Años , Arteriopatías Oclusivas/diagnóstico por imagen , Medios de Contraste , Estudios de Factibilidad , Femenino , Arteria Femoral/diagnóstico por imagen , Arteria Femoral/patología , Peroné/irrigación sanguínea , Pie/irrigación sanguínea , Humanos , Arteria Ilíaca/diagnóstico por imagen , Arteria Ilíaca/patología , Pierna/diagnóstico por imagen , Masculino , Persona de Mediana Edad , Arteria Poplítea/diagnóstico por imagen , Arteria Poplítea/patología , Estudios Retrospectivos , Sensibilidad y Especificidad , Método Simple Ciego , Arterias Tibiales/diagnóstico por imagen , Arterias Tibiales/patología
8.
J Vasc Interv Radiol ; 9(5): 786-92, 1998.
Artículo en Inglés | MEDLINE | ID: mdl-9756068

RESUMEN

PURPOSE: To compare the rates of thrombolysis produced by forced intrathrombic injections of saline versus urokinase, as well as automated versus manual injections of urokinase, with use of an in vitro model of a vascular occlusion. MATERIALS AND METHODS: The rates of thrombolysis produced by forced intrathrombic injections of saline and urokinase were compared in an in vitro radiometric model utilizing I-125-labeled thrombus. Similar experiments were performed to compare manual and automated injections of urokinase. The dissolution of the thrombus was quantitatively monitored with use of a scintillation detector. Averaged time activity data for each type of experiment were fit to exponential functions and half times of lysis calculated. The differences in the half times for the experiments being compared were evaluated for significance with use of the Student t test. RESULTS: The half times of lysis produced by forced intrathrombic injections of urokinase were substantially and significantly shorter than those produced by forced saline injections. The half time of lysis produced by automated injections was not significantly different than that produced by manual injections. CONCLUSIONS: Forced intrathrombic injections of urokinase produce faster and substantially more thrombolysis when compared with similarly administered saline. Also, for forced intrathrombic injections of lytic agents, an automated injector is an equivalent alternative to manual injections.


Asunto(s)
Activadores Plasminogénicos/administración & dosificación , Terapia Trombolítica/métodos , Trombosis/tratamiento farmacológico , Activador de Plasminógeno de Tipo Uroquinasa/administración & dosificación , Cateterismo , Humanos , Inyecciones/instrumentación , Inyecciones/métodos , Cloruro de Sodio/administración & dosificación , Terapia Trombolítica/instrumentación
9.
Magn Reson Med ; 39(5): 691-6, 1998 May.
Artículo en Inglés | MEDLINE | ID: mdl-9581598

RESUMEN

To acquire multiple longitudinal locations in the lower extremity after a single contrast injection, appropriate table translation and contrast injection are required. An approximate model based on constant bolus velocity was developed to describe the space-time course of a contrast bolus in the lower extremity. This model was verified in dynamic MR angiograms acquired in a group of patients using time-resolved 2D MR digital subtraction angiography (MRDSA). From this contrast bolus passage model, a timing algorithm for table translation and contrast injection was developed for bolus chase MRDSA, subsequently validated in bolus chase 2D MRDSA experiments. All targeted major peripheral arteries were well depicted in bolus chase 2D MRDSA using this timing algorithm and a single 15-ml contrast dose.


Asunto(s)
Algoritmos , Angiografía por Resonancia Magnética/métodos , Técnica de Sustracción , Adulto , Medios de Contraste , Femenino , Gadolinio DTPA , Humanos , Inyecciones Intravenosas , Pierna/irrigación sanguínea , Masculino , Enfermedades Vasculares Periféricas/diagnóstico , Factores de Tiempo
10.
Radiology ; 207(1): 263-9, 1998 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-9530326

RESUMEN

A bolus-chase magnetic resonance (MR) angiographic technique performed with a prototypic stepping table and coil holder and a 15-20-mL injection of contrast material was developed to depict the entire lower extremity. Image acquisition was synchronized with passage of the contrast medium bolus through the lower extremity. Ten subjects underwent the examination, which was performed in less than 1 minute. All major arteries were well demonstrated in all cases.


Asunto(s)
Medios de Contraste/administración & dosificación , Gadolinio DTPA , Pierna/irrigación sanguínea , Angiografía por Resonancia Magnética/métodos , Técnica de Sustracción , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Gadolinio DTPA/administración & dosificación , Humanos , Inyecciones Intravenosas , Angiografía por Resonancia Magnética/instrumentación , Masculino , Persona de Mediana Edad
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