Virtual Non-Contrast Spectral CT in Renal Masses: Is It Time to Discard Conventional Unenhanced Phase?

Dual-layer Dual-Energy CT (dl-DECT) allows one to create virtual non-contrast (VNC) reconstructions from contrast-enhanced CT scans, with a consequent decrease of the radiation dose. This study aims to assess the reliability of VNC for the diagnostic evaluation of renal masses in comparison with true non-contrast (TNC) images. The study cohort included 100 renal masses in 40 patients who underwent dl-DECT between June and December 2021. Attenuation values and standard deviations were assessed through the drawing of regions of interest on TNC and VNC images reconstructed from corticomedullary and nephrographic phases. A Wilcoxon signed-rank test was performed in order to assess equivalence of data and Spearman's Rho correlation coefficient to evaluate correlations between each parameter. The diagnostic accuracy of VNC was estimated through the performance of receiver operating characteristic (ROC) curve analysis. Differences between attenuation values were, respectively, 74%, 18%, 5% and 3% (TNC-VNC_cort), and 74%, 15%, 9% and 2% (TNC-VNC_neph). The Wilcoxon signed-rank test demonstrated the equivalence of attenuation values between the TNC and VNC images. The diagnostic performance of VNC images in the depiction of kidney simple cysts remains high compared to TNC (VNC_cort-AUC: 0.896; VNC_neph-AUC: 0.901, TNC-AUC: 0.903). In conclusion, quantitative analysis of attenuation values showed a strong agreement between VNC and TNC images in the evaluation of renal masses.

Comparison of point-shear wave elastography (ElastPQ) and transient elastography (FibroScan) for liver fibrosis staging in patients with non-alcoholic fatty liver disease

BACKGROUND AND AIMS

ElastPQ is a point shear wave elastography technique used to non-invasively assess liver fibrosis. We compared liver stiffness measurements (LSM) by ElastPQ and fibroscan transient elastography (F-TE) in a cohort of patients with non-alcoholic fatty liver disease (NAFLD). We further evaluated the performance of ElastPQ in a subgroup of patients with available liver histology.

MATERIALS AND METHODS

We included patients with NAFLD who presented in a dedicated multidisciplinary clinic. Anthropometric parameters, blood tests and elastography measurements were obtained using F-TE and ElastPQ as part of routine clinical care.

RESULTS

We enrolled 671 patients with NAFLD, mean age 55.8 ± 13 years, body mass index (BMI) 31.5 ± 5.7 kg/m² , 56.6% males, 41% diabetes, 53.7% hypertension, 68% dyslipidaemia. ElastPQ showed an excellent correlation with F-TE (Spearman's r = 0.80, p < .001), which was better for mild/moderate stages of fibrosis. Independent predictors of a >2 kPa discrepancy between the two techniques were a larger waist circumference and F-TE ≥10 kPa. In the subgroup of 159 patients with available histology, ElastPQ showed similar diagnostic accuracy with F-TE in staging liver fibrosis (ElastPQ area under the curves 0.84, 0.83, 0.86 and 0.95, for F ≥ 1, F ≥ 2, F ≥ 3 and F = 4 respectively). Optimal cut-off values of ElastPQ for individual fibrosis stages were lower than those of F-TE.

CONCLUSIONS

ElastPQ shows an excellent correlation with F-TE in patients with NAFLD, which was better for lower LSM. The optimal cut-off values of ElastPQ are lower than those of F-TE for individual stages of fibrosis. ElastPQ has similar diagnostic accuracy to F-TE for all stages of fibrosis.