Longitudinal changes in renal volumes evaluated by automated three-dimensional volumetric computed tomography of the whole kidney: The association with the renal function and disease progression.

PURPOSE: To clarify the changes in the total renal volume over time with changes of the renal function using automated 3D volumetric CT of the whole kidney and to evaluate the usefulness of the total renal volume CT measurement in predicting chronic kidney disease (CKD) grade progression. METHODS: A total of 961 patients who underwent abdominal CT at least twice (an interval of more than 4 years) were included. The automated 3D volumetric CT measurement of the whole kidney was performed at the initial and latest CT examination. Patients with CKD grade G2 at the time of the initial CT were divided into two groups: a progression group (CKD grade progressed to G3-G5) and a non-progression group. Changes in the renal volume over time were compared between the two groups. RESULTS: The volume of both kidneys measured on initial CT was positively correlated with eGFR (ρ = 0.490, p < 0.001). There was a significant difference in the initial volume of both kidneys among CKD grades (p < 0.001, G1:318.7 ± 60.5 ml, G2:275.5 ± 53.5 ml, G3:233.7 ± 46.9 ml, G4:183.2 ± 22.5 ml, G5:157.7 ± 77.4 ml). When comparing the progression and non-progression groups, the initial volume of both kidneys was significantly smaller in the progression group, compared with the non-progression group (252.0 ± 50.6 ml vs. 278.9 ± 53.7 ml). In addition, the annual reduction volume in both the right and left kidneys was significantly greater in the progression group than in the non-progression group (p < 0.001). CONCLUSION: The automated 3D volumetric CT measurement of the whole kidney has the potential to monitor changes in renal volume over time with changes of the renal function.

Impact on the image quality of modified reduced field-of-view diffusion-weighted magnetic resonance imaging of pancreatic adenocarcinoma using spatially tailored two-dimensional radiofrequency pulses with a tilted excitation plane: A comparison with conventional field-of-view imaging.

PURPOSE: Modified reduced FOV diffusion-weighted imaging (DWI) using spatially-tailored 2D RF pulses with tilted excitation plane (tilted r-DWI) has been developed. The purpose of this study was to evaluate the impact on image quality and quantitative apparent diffusion coefficient (ADC) values of tilted r-DWI for pancreatic ductal adenocarcinomas (PDAC) in comparison to conventional full-FOV DWI (f-DWI). METHODS: This retrospective study included 21 patients (mean 70.7, range 50-85 years old) with pathologically confirmed PDAC. All MR images were obtained using 3 T systems. Two radiologists evaluated presence of blurring or ghost artifacts, susceptibility artifacts, and aliasing artifacts; anatomic visualization of the pancreas; interslice signal homogeneity; overall image quality; and conspicuity of the PDAC. For quantitative analysis, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), signal-intensity ratio (SIR) and ADC values were measured using regions of interest. RESULTS: All image quality scores except aliasing artifacts in tilted r-DWI were significantly higher than those in f-DWI (p < 0.01). The CNR and SIR of PDAC were significantly higher in tilted r-DWI than in f-DWI (6.7 ± 4.4 vs. 4.7 ± 3.9, 2.02 ± 0.72 vs. 1.72 ± 0.60, p < 0.01). Conversely, the SNR of PDAC in tilted r-DWI was significantly lower than that in f-DWI (56.0 ± 33.1 vs. 113.6 ± 67.3, p < 0.01). No significant difference was observed between mean ADC values of the PDAC calculated from tilted r-DWI (tilted r-ADC) and those from f-DWI (f-ADC) (1225 ± 250 vs. 1294 ± 302, p = 0.11). CONCLUSION: The r-DWI using 2D RF techniques with a tilted excitation plane was shown to significantly improve the image quality and CNR and reduce image artifacts compared to f-DWI techniques in MRI evaluations of PDAC without significantly affecting ADC values.

Dual-Source Contrast-Enhanced Multiphasic CT of the Liver Using Low Voltage (70 kVp): Feasibility of a Reduced Radiation Dose and a 50% of Contrast Dose.

This study investigated the feasibility of both a reduced radiation dose and a 50% of contrast dose in multiphasic CT of the liver with a 70 kVp protocol compared with a standard-tube-voltage protocol derived from dual-energy (DE) CT (blended DE protocol) with a full-dose contrast-agents in the same patient group. This study included 46 patients who underwent multiphasic contrast-enhanced dynamic CT of the liver with both a 70 kVp and a blended DE protocols. For quantitative analysis, median CT values for the liver, aorta, and portal vein, as well as signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), were measured and calculated. In addition, as a qualitative analysis, the contrast effect and overall image quality of the abdominal organs were evaluated on a five-point scale. CNR and SNR of the hepatic parenchyma were not significantly different between the 70kV protocol and the Blended DE protocol in all phases. The 70 kVp protocol showed significantly better image quality compared with the blended DE protocol in the arterial phase (p = 0.035) and the equilibrium layer phase (p = 0.016). A 70 kVp CT protocol in combination with a reduced radiation dose and half-dose iodine load is feasible for multiphasic dynamic CT of the liver by maintaining the contrast enhancement effects and image quality in comparison with the blended DE CT protocol.

Automated whole-volume measurement of CT fat fraction of the pancreas: correlation with Dixon MR imaging.

OBJECTIVES: This study aimed to assess the feasibility of pancreatic steatosis quantification by automated whole-volume measurement of the fat fraction of the pancreas on CT in comparison to MRI using proton-density fat fraction (PDFF) techniques. METHODS: Fifty-nine patients who underwent both CT and MRI were analyzed. Automated whole-volume measurement of pancreatic fat on unenhanced CT was performed by a histogram analysis with local thresholding. Three sets of CT fat volume fraction (FVF) (%) values with thresholds of -30 Hounsfield unit (HU), -20 HU and -10 HU were compared to MR-FVF (%) values measured on a PDFF map. RESULTS: The median -30 HU CT-FVF, -20 HU CT-FVF, -10 HU CT-FVF and MR-FVF values of the pancreas were 8.6% (interquartile range (IQR), 11.3), 10.5% (IQR, 13.2), 13.4% (IQR, 16.1) and 10.9% (IQR, 9.7), respectively. The -30 HU CT-FVF (%), -20 HU CT-FVF (%) and -10 HU CT-FVF (%) of the pancreas showed a significant positive correlation with the MR-FVF (%) of the pancreas (ρ = 0.898, p < 0.001, ρ = 0.905, p < 0.001, ρ = 0.909, p < 0.001, respectively). The -20 HU CT-FVF (%) displayed reasonable agreement with the MR-FVF (%) with a low absolute fixed bias (mean difference, 0.32%; limit of agreement from -10.1 to 10.7%). CONCLUSION: The automated whole-volume measurement of the CT fat fraction of the pancreas using the threshold CT attenuation value of -20 HU may be a feasible, non-invasive, and convenient technique for quantifying pancreatic steatosis. ADVANCES IN KNOWLEDGE: CT-FVF value of the pancreas had a positive correlation with the MR-FVF value. The -20 HU CT-FVF may be a convenient technique for quantifying pancreatic steatosis.