RESUMEN
BACKGROUND: There has been increasing interest in the superficial circumflex iliac artery perforator (SCIP) flap as a source of thin, pliable soft tissue combined with a favorable donor site. Despite several clinical series from Asia, barriers to adoption include reluctance to perform submillimeter "supermicrosurgery" and the effect of body habitus on flap feasibility. The purpose of this study is to distinguish vascular anatomic characteristics of the SCIP flap in a North American population. METHODS: Computed tomography angiography was examined in 84 flaps in healthy prospective renal donor patients from a radiographic database. Descriptive statistics as well as linear regression comparing variables to body mass index (BMI) were performed. RESULTS: Mean BMI was 27.1 ± 3.5 kg/m2, while the mean patient age was 47.8 ± 11.4 years. The superficial circumflex iliac artery (SCIA) originated from the common femoral artery in 92% cases, with remainder originating from the profunda femoris. The mean vessel diameter was 1.85 mm at source vessel origin. Distance from skin to source vessel averaged 30.7 mm. Suprascarpal subcutaneous thickness averaged 16.5 mm. The mean distance from Scarpa's fascia to vessel origin was 14.1 mm. Direct three-dimensional distance from vessel origin to pubic tubercle was 50.2 mm. A medial and lateral perforator split off of the SCIA was observed in 38 cases (45%). Significant differences were shown when comparing BMI to skin to source vessel distance (p < 0.001), suprascarpal subcutaneous fat thickness (p < 0.001), and fascial distance to vessel origin (p < 0.001). BMI did not significantly affect vessel diameter. CONCLUSION: Despite a significantly higher BMI than many previously published cohorts, the SCIP remains an excellent source of thin and pliable tissue. When dissected closer to the source vessel, a vessel caliber of nearly 2 mm can be achieved, which may obviate the need for "supermicrosurgery" in this population.
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Colgajos Tisulares Libres , Colgajo Perforante , Procedimientos de Cirugía Plástica , Niño , Humanos , Arteria Ilíaca/diagnóstico por imagen , Arteria Ilíaca/cirugía , Estudios ProspectivosRESUMEN
OBJECTIVES: The aim of this study was to assess the impact of oral water and intravenous furosemide challenges on blood oxygenation level-dependent magnetic resonance imaging measurements in the kidney and to examine the contribution of R2 (=1/T2) to changes in R2* (=1/T2*). MATERIALS AND METHODS: This Health Insurance Portability and Accountability Act-compliant study had institutional review board approval, and written informed consent was obtained from all subjects. Nine healthy volunteers were imaged at 3 T on 2 visits. During each visit, a baseline fasting magnetic resonance acquisition was followed by a diuretic challenge: oral water load for the first visit and furosemide for the second. R2* and R2 values in the renal cortex and medulla were measured using multiple gradient echo and multiple spin echo sequences, respectively, and R2' values were computed as R2' = R2* - R2. Timed urinary output was also measured. RESULTS: Averaged across all subjects, the R2* response to furosemide was greater than to water and greater in the medulla than the cortex. The mean R2 responses exhibited the same trends but were uniformly smaller than the mean R2* responses. The peak changes in R2* and R2 appeared, on average, 10 to 14 minutes before peak urinary output. The median percentage contribution of R2 to R2* changes was 16% in the medulla after both challenges. In the cortex, the median contribution was 48% after water load and 58% after furosemide challenge. CONCLUSIONS: The contributions of R2 to R2* changes after water load and furosemide challenge are not negligible, especially in the renal cortex. In routine clinical practice, R2* could be used alone as a rough surrogate for R2' in the medulla. However, in the cortex, both R2 and R2* should be measured to obtain accurate values of R2'.
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Furosemida/administración & dosificación , Riñón/metabolismo , Angiografía por Resonancia Magnética/métodos , Oximetría/métodos , Oxígeno/sangre , Circulación Renal/fisiología , Agua/administración & dosificación , Administración Oral , Adulto , Diuréticos/administración & dosificación , Femenino , Humanos , Inyecciones Intravenosas , Riñón/efectos de los fármacos , Pruebas de Función Renal/métodos , Masculino , Circulación Renal/efectos de los fármacos , Distribución Tisular , Adulto JovenRESUMEN
PURPOSE: To assess the reproducibility and the distribution of intravoxel incoherent motion (IVIM) and diffusion-tensor (DT) imaging parameters in healthy renal cortex and medulla at baseline and after hydration or furosemide challenges. MATERIALS AND METHODS: Using an institutional review board-approved HIPAA-compliant protocol with written informed consent, IVIM and DT imaging were performed at 3 T in 10 volunteers before and after water loading or furosemide administration. IVIM (apparent diffusion coefficient [ADC], tissue diffusivity [D(t)], perfusion fraction [f(p)], pseudodiffusivity [D(p)]) and DT (mean diffusivity [MD], fractional anisotropy [FA], eigenvalues [λ(i)]) imaging parameters and urine output from serial bladder volumes were calculated. (a)Reproducibility was quantified with coefficient of variation, intraclass correlation coefficient, and Bland-Altman limits of agreement; (b) contrast and challenge response were quantified with analysis of variance; and (c) Pearson correlations were quantified with urine output. RESULTS: Good reproducibility was found for ADC, D(t), MD, FA, and λ(i) (average coefficient of variation, 3.7% [cortex] and 5.0% [medulla]), and moderate reproducibility was found for D(p), f(p), and f(p) · D(p) (average coefficient of variation, 18.7% [cortex] and 25.9% [medulla]). Baseline cortical diffusivities significantly exceeded medullary values except D(p), for which medullary values significantly exceeded cortical values, and λ(1,) which showed no contrast. ADC, D(t), MD, and λ(i) increased significantly for both challenges. Medullary diffusivity increases were dominated by transverse diffusion (1.72 ± 0.09 [baseline] to 1.79 ± 0.10 [hydration] µm(2)/msec, P = .0059; or 1.86 ± 0.07 [furosemide] µm(2)/msec, P = .0094). Urine output correlated with cortical ADC with furosemide (r = 0.7, P = .034) and with medullary λ(1) (r = 0.83, P = .0418), λ(2) (r = 0.85, P = .0301), and MD (r = 0.82, P = .045) with hydration. CONCLUSION: Diffusion MR metrics are sensitive to flow changes in kidney induced by diuretic challenges. The results of this study suggest that vascular flow, tubular dilation, water reabsorption, and intratubular flow all play important roles in diffusion-weighted imaging contrast.
Asunto(s)
Imagen de Difusión Tensora/métodos , Diuréticos/administración & dosificación , Furosemida/administración & dosificación , Furosemida/metabolismo , Riñón/metabolismo , Adulto , Algoritmos , Análisis de Varianza , Anisotropía , Femenino , Humanos , Inyecciones Intravenosas , Masculino , Movimiento (Física) , Reproducibilidad de los ResultadosRESUMEN
PURPOSE: To assess the accuracy of glomerular filtration rate (GFR) measurements obtained with low-contrast agent dose dynamic contrast material-enhanced magnetic resonance (MR) renography in patients with liver cirrhosis who underwent routine liver MR imaging, with urinary clearance of technetium 99m ((99m)Tc) pentetic acid (DTPA) as the reference standard. MATERIALS AND METHODS: This HIPAA-compliant study was institutional review board approved. Written informed patient consent was obtained. Twenty patients with cirrhosis (14 men, six women; age range, 41-70 years; mean age, 54.6 years) who were scheduled for routine 1.5-T liver MR examinations to screen for hepatocellular carcinoma during a 6-month period were prospectively included. Five-minute MR renography with a 3-mL dose of gadoteridol was performed instead of a routine test-dose timing examination. The GFR was estimated at MR imaging with use of two kinetic models. In one model, only the signal intensities in the aorta and kidney parenchyma were considered, and in the other, renal cortical and medullary signal intensities were treated separately. The GFR was also calculated by using serum creatinine levels according to the Cockcroft-Gault and modification of diet in renal disease (MDRD) formulas. All patients underwent a (99m)Tc-DTPA urinary clearance examination on the same day to obtain a reference GFR measurement. The accuracies of all MR- and creatinine-based GFR estimations were compared by using Wilcoxon signed rank tests. RESULTS: The mean reference GFR, based on (99m)Tc-DTPA clearance, was 74.9 mL/min/1.73 m(2) ± 27.7 (standard deviation) (range, 10.3-120.7 mL/min/1.73 m(2)). With both kinetic models, 95% of MR-based GFRs were within 30% of the reference values, whereas only 40% and 60% of Cockcroft-Gault- and MDRD-based GFRs, respectively, were within this range. MR-based GFR estimates were significantly more accurate than creatinine level-based estimates (P < .001). CONCLUSION: GFR assessment with MR imaging, which outperformed the Cockcroft-Gault and MDRD formulas, adds less than 10 minutes of table time to a clinically indicated liver MR examination without ionizing radiation. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101338/-/DC1.