RESUMEN
PURPOSE: To prospectively compare the blood oxygen level-dependent (BOLD) magnetic resonance (MR) signal intensity of calf muscle during ischemia and reactive hyperemia with laser Doppler flowmetry (LDF) and transcutaneous oxygen pressure (TcPo2) measurements, two parameters routinely used to evaluate peripheral arterial occlusive disease. MATERIALS AND METHODS: The study was institutional review board approved; all volunteers gave informed consent. Fifteen healthy volunteers (eight male, seven female; mean age, 33.0 years +/- 6.1 [standard deviation]) underwent LDF, TcPo2 measurement, and BOLD MR imaging of the calf during ischemia and reactive hyperemia. The BOLD signal intensity of the gastrocnemius muscle was measured at 1.5-T single-shot multiecho gradient-echo echo-planar imaging. Time to half ischemia minimum (THIM), time to half hyperemia peak (THHP), and time to peak (TTP) after cuff deflation were measured with each method. Correlation coefficients (CCs) for associations of BOLD response with LDF and TcPo2 time courses were calculated. Student t testing of key BOLD MR, LDF, and TcPo2 measurement parameters was performed. RESULTS: During ischemia, normalized LDF and TcPo2 measurements decreased similarly to BOLD MR signal intensity (CCs: 0.86 and 0.96 for associations with LDF and TcPo2 measurements, respectively). Mean THIM values were 136.0, 82.5, and 121.3 seconds for BOLD MR, LDF (P < .01), and TcPo2 (P > .05) measurements, respectively. During early reactive hyperemia, LDF and TcPo2 measurements increased rapidly to peak values, similarly to BOLD MR signal intensity (CCs: 0.81 and 0.78, respectively). Mean THHP values were 26.0, 12.5, and 44.0 seconds for BOLD MR, LDF (P < .01), and TcPo2 (P < .01) measurements, respectively. Mean TTP values were 48.7, 47.5, and 98.0 seconds for BOLD MR, LDF (P > .05), and TcPo2 (P < .01) measurements, respectively. CONCLUSION: BOLD MR imaging of calf muscles-depending on underlying key parameters-has moderate to good correlation with LDF and TcPo2 measurements during ischemia and reactive hyperemia.
Asunto(s)
Arteriopatías Oclusivas/diagnóstico , Isquemia/diagnóstico , Pierna/irrigación sanguínea , Imagen por Resonancia Magnética/métodos , Músculo Esquelético/irrigación sanguínea , Enfermedades Vasculares Periféricas/diagnóstico , Adulto , Arteriopatías Oclusivas/fisiopatología , Velocidad del Flujo Sanguíneo/fisiología , Monitoreo de Gas Sanguíneo Transcutáneo , Femenino , Humanos , Hiperemia , Procesamiento de Imagen Asistido por Computador , Isquemia/fisiopatología , Flujometría por Láser-Doppler , Masculino , Oxígeno/metabolismo , Enfermedades Vasculares Periféricas/fisiopatología , Estudios Prospectivos , Flujo Sanguíneo Regional/fisiologíaRESUMEN
BACKGROUND: Blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) has been used to measure T2* changes in skeletal muscle tissue of healthy volunteers. The BOLD effect is assumed to primarily reflect changes in blood oxygenation at the tissue level. We compared the calf muscle BOLD response of patients with peripheral arterial occlusive disease (PAOD) to that of an age-matched non-PAOD group during postischemic reactive hyperemia. METHODS AND RESULTS: PAOD patients (n=17) with symptoms of intermittent calf claudication and an age-matched non-PAOD group (n=11) underwent T2*-weighted single-shot multiecho planar imaging on a whole-body magnetic resonance scanner at 1.5 T. Muscle BOLD MRI of the calf was performed during reactive hyperemia provoked by a cuff-compression paradigm. T2* maps were generated with an automated fitting procedure. Maximal T2* change (deltaT2*(max)) and time to peak to reach deltaT2*(max) for gastrocnemius, soleus, tibial anterior, and peroneal muscle were evaluated. Compared with the non-PAOD group, patients revealed significantly lower deltaT2*(max)-values, with a mean of 7.3+/-5.3% versus 13.1+/-5.6% (P<0.001), and significantly delayed time-to-peak values, with a mean of 109.3+/-79.3 versus 32.2+/-13.3 seconds (P<0.001). CONCLUSIONS: T2* time courses of the muscle BOLD MRI signal during postocclusive reactive hyperemia revealed statistically significant differences in the key parameters (deltaT2*(max); time to peak) in PAOD patients compared with age-matched non-PAOD controls.
Asunto(s)
Arteriopatías Oclusivas/patología , Imagen por Resonancia Magnética/métodos , Músculo Esquelético/patología , Anciano , Arteriopatías Oclusivas/sangre , Arteriopatías Oclusivas/complicaciones , Estudios de Casos y Controles , Imagen Eco-Planar , Femenino , Humanos , Hiperemia/sangre , Hiperemia/etiología , Hiperemia/patología , Pierna/irrigación sanguínea , Masculino , Persona de Mediana Edad , Músculo Esquelético/irrigación sanguínea , Oxígeno/sangre , Factores de TiempoRESUMEN
PURPOSE: To reduce venous contamination at the calf level in three-dimensional contrast-enhanced MR angiography (CE-MRA) by applying continuous infragenual cuff-compression. MATERIALS AND METHODS: Ten patients with clinically relevant peripheral arterial occlusive disease (PAOD) underwent dynamic three-dimensional CE-MRA of the calf. Six consecutive measurements were acquired with the first measurement serving as mask. Cuff-compression of 50 mmHg was attached below the knee. To allow intra-individual comparison, compression was applied unilaterally. The cuff was inflated three minutes before scanning and was continued throughout the MRA session. Venous contamination and arterial visualization scores were ranked using a five-point rating scale. Contrast-to-noise ratios (CNRs) of superficial enhancing calf-veins on the uncompressed and compressed calf sides were evaluated. An asymmetry index (AI) defined by CNR(mean) (uncompressed)/CNR(mean) (compressed) was introduced to describe the ratio in venous contrast agent supply between both sides quantitatively. RESULTS: Three-dimensional CE-MRA of the calves demonstrated significantly lower superficial venous contamination scores (P < 0.004) and clearly improved arterial visualization (P < 0.009) on the compressed side. Additionally, AI values were larger than 1 (P < 0.02), indicating a higher contrast agent supply in the superficial veins on the uncompressed side. CONCLUSION: Infragenual cuff-compression minimizes venous overlay in three-dimensional CE-MRA at calf level by reduction of contrast agent supply in the superficial veins.