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PURPOSE: This study aimed to evaluate the association of portal flow hemodynamics with lobar hepatic steatosis by means of dynamic contrast-enhanced (DCE) CT. METHODS: The study population consisted of 235 patients, 77 with lobar hepatic steatosis (right, n = 67; left, n = 10), 158 with diffuse hepatic steatosis with (n = 76) and without (n = 82) a focal fatty spared area. CT attenuation values (Hounsfield units: HU) of the liver with and without hepatic steatosis were measured in unenhanced and arterial-phase CT. The contrast enhancement (CE) values were calculated as the difference in HU values between unenhanced and arterial-phase CT. RESULTS: In 67 patients with lobar steatosis of the right lobe, the median CE values of the areas of right lobar steatosis were significantly lower than those of the non-fatty left lobe (13 [IQR 7-19] vs 23 [13-33] HU, P < 0.01), suggesting dominant SMV flow to the right lobe with lobar hepatic steatosis. Conversely, in 10 patients with lobar steatosis of the left lobe, the median CE values of the areas of left lobar steatosis were lower than those of the non-fatty right lobe (15.5 [11.75-21.5] vs 16 [14.5-22] HU); however, this difference was not statistically significant (P = 0.20). In 76 patients with a focal fatty spared area, there were significant differences in the median CE values between hepatic steatosis areas and focal fatty spared areas in the gallbladder fossa group (P = 0.01) and in the segment IV group (P < 0.01). CONCLUSION: Lobar hepatic steatosis may be associated with regional changes of the portal flow hemodynamics (i.e., predominant perfusion from the SMV flow to the lobes with steatosis).
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Hígado Graso , Humanos , Hígado Graso/diagnóstico por imagen , Hígado , Tomografía Computarizada por Rayos X , Estudios RetrospectivosRESUMEN
PURPOSE: To investigate the clinical value of measuring the ECV fraction of the pancreas by DECT in association with an impaired glucose tolerance (IGT) estimated by the hemoglobin A1C (HbA1C) value in patients with or without cirrhosis. MATERIALS AND METHODS: This retrospective study included patients who underwent contrast-enhanced dynamic CT with dual-energy mode between March 2018 and February 2019. The ECV fraction of the pancreas was calculated from iodine map images created from equilibrium-phase contrast-enhanced DECT images. The cross-sectional areas of the pancreas were also measured. RESULTS: In total, 51 patients were analyzed (median age, 69 years old; 22 women). The ECV fraction of the pancreas showed a significant negative correlation with the HbA1c value in the cirrhotic group (ρ=-0.346, p = 0.048), while there was no significant correlation in the non-cirrhotic group (ρ=-0.086, p = 0.734). In the elevated HbA1C group, the ECV fraction of the pancreas in the cirrhotic patients (median, 0.247; interquartile range [IQR], 0.098) was significantly lower than that in the non-cirrhotic patients (0.332, IQR 0.113) (p = 0.024). In the elevated HbA1C group, the cross-sectional area of the pancreas was significantly larger in the cirrhotic patients than that in the non-cirrhotic patients (median [IQR]; 2945 [904] vs. 1885 [909] mm2, p = 0.019). CONCLUSION: A reduction in the ECV fraction of the pancreas measured by DECT as well as the enlargement of the pancreatic parenchyma was observed in cirrhotic patients with IGT. These findings suggest that the measurement of the pancreatic ECV fraction by DECT may help clarify the pathophysiology of IGT in patients with cirrhosis.
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Intolerancia a la Glucosa , Anciano , Medios de Contraste , Femenino , Humanos , Páncreas/diagnóstico por imagen , Estudios Retrospectivos , TomografíaRESUMEN
BACKGROUND: Reduced field-of-view diffusion-weighted imaging (rDWI) with tilted two-dimensional radiofrequency (RF) excitation planes has not yet been applied to the imaging of the pancreas although the utility of this technique which allows the acquisition of high-quality images without aliasing artifacts in the phase-encoding direction has been evaluated for brain and spinal cord imaging. PURPOSE: To evaluate the visual image quality of the pancreas by tilting the excitation plane (tilted rDWI) in comparison to conventional DWI (cDWI) and rDWI without using the tilted excitation plane. STUDY TYPE: Retrospective. POPULATION: Thirty-two patients evaluated for suspected pancreatobiliary diseases. FIELD STRENGTH/SEQUENCE: Echo-planar imaging DWI (cDWI, rDWI, and tilted rDWI) acquired at 3 T. ASSESSMENT: Images from each DWI sequence were analyzed by five radiologists to compare image quality (conspicuity of pancreatic edges, interslice signal homogeneity, overall image quality, and conspicuity of focal pancreatic lesions) and artifacts (presence of blurring or ghosting artifacts, susceptibility artifacts, and aliasing artifact). STATISTICAL TESTS: Shapiro-Wilk test was performed to assess whether data were normally distributed. Friedman test followed by Bonferroni-adjusted Wilcoxon signed-rank test for post hoc analysis was performed to compare image quality and artifact scores. RESULTS: The mean scores for conspicuity of pancreatic edges (3.36 vs. 2.37), interslice signal homogeneity (3.14 vs. 2.81), presence of ghosting artifacts (3.32 vs. 2.66), susceptibility artifacts (3.06 vs. 2.30), and aliasing artifacts (3.90 vs. 2.34), and overall image quality (3.49 vs. 2.36) were significantly higher in the tilted rDWI than in the rDWI (P < 0.017 for all parameters). The conspicuity score for focal pancreatic lesions tended to be higher in tilted rDWI than in rDWI (2.44 vs. 2.00, P = 0.07). DATA CONCLUSION: Tilted rDWI had better image quality and reduced artifacts relative to cDWI and rDWI techniques in the pancreas. LEVEL OF EVIDENCE: 4 TECHNICAL EFFICACY: Stage 2.
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Imagen de Difusión por Resonancia Magnética , Imagen Eco-Planar , Artefactos , Humanos , Imagen por Resonancia Magnética , Páncreas/diagnóstico por imagen , Reproducibilidad de los Resultados , Estudios RetrospectivosRESUMEN
PURPOSE: To compare the occurrence of transient respiratory motion artifacts (TRMAs) in multiple arterial phases on abdominal magnetic resonance (MR) images between those obtained using gadobutrol and gadoxetate disodium. MATERIALS AND METHODS: Two hundred and fourteen abdominal MR examinations (101 with gadoxetate disodium, 113 with gadobutrol) were evaluated. Dynamic three-dimensional contrast-enhanced T1-weighted imaging (CAIPIRINHA-Dixon-TWIST-VIBE) including single-breath-hold six arterial phase acquisitions was performed on a 3.0-T MRI scanner. The TRMAs frequency and the mean TRMA scores were compared between patients assessed with gadoxetate disodium and those assessed with gadobutrol. In addition, the timing of TRMAs appearing for the first time was also recorded and compared between the two groups. RESULTS: The mean TRMA scores in all arterial phases using gadoxetate disodium were significantly worse than in those using gadobutrol (1.49 ± 0.78 vs. 1.18 ± 0.53, P < .001). Regarding the timing of the occurrence of TRMAs, the severe TRMAs frequency after the third arterial phase was significantly higher in patients using gadoxetate disodium (10/101, 10%) than in those using gadobutrol (0/113, 0%) (P < .001). CONCLUSION: In multiple-arterial-phase dynamic MRI, the TRMAs frequency when using gadoxetate disodium increased compared with gadobutrol, due to intolerable respiratory suspension after the third arterial phase.
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Abdomen/diagnóstico por imagen , Artefactos , Medios de Contraste , Gadolinio DTPA , Hígado/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Compuestos Organometálicos , Adulto , Anciano , Anciano de 80 o más Años , Arterias/diagnóstico por imagen , Contencion de la Respiración , Medios de Contraste/administración & dosificación , Femenino , Gadolinio DTPA/administración & dosificación , Humanos , Imagenología Tridimensional , Hígado/irrigación sanguínea , Espectroscopía de Resonancia Magnética , Masculino , Persona de Mediana Edad , Movimiento (Física) , Compuestos Organometálicos/administración & dosificación , Estudios Retrospectivos , Factores de RiesgoRESUMEN
OBJECTIVES: Although it is important to quantify the degree of fatty degeneration of the pancreas, it is difficult to make such a quantification using conventional computed tomography (CT). The present study evaluated the feasibility of pancreatic fat quantification by dual-energy CT (DECT) compared with T2*-corrected six-point Dixon magnetic resonance imaging (MRI). MATERIALS AND METHODS: Twenty-eight patients who underwent both DECT (100 and 150 kVp) and Dixon MRI without the use of contrast agents were analyzed. The region of interest (ROI) was placed at the head and body/tail of the pancreas on fat volume fraction (FVF) maps generated using the multi-material decomposition (MMD) algorithm on DECT. The FVF (%) of pancreatic parenchyma measured by DECT (CT-FVF) was compared with that measured on FVF maps calculated using Dixon MRI (MR-FVF) using the Spearman rank correlation coefficient. RESULTS: The median CT-FVF (%) values of the head and body/tail of the pancreas on DECT were 14.2% (range 0.1-81.2%) and 9.4% (range 0-40.8%), respectively. The median MR-FVF (%) values of the head and body/tail of the pancreas on Dixon MRI were 12.2% (range 1.2-80.9%) and 8.1% (range 0.3-43.7%), respectively. CT-FVF (%) measured by DECT showed a significant correlation with the MR-FVF (%) measured by Dixon MRI in the head of the pancreas (ρ = 0.631, P < 0.001) as well as the body/tail of the pancreas (ρ = 0.526, P = 0.004). CONCLUSION: DECT may be useful for quantifying the degree of fatty degeneration of the pancreas.