SWE in CKD

 

ABSTRACT

To evaluate renal parenchymal stiffness using 2D shear wave elastography (SWE) in patients with chronic kidney disease (CKD) and to investigate the correlation between SWE results and demographic as well as laboratory findings. We evaluated 41 CKD patients and 40 controls who underwent abdominal ultrasound (US) between December 2020 and November 2022. SWE measurements were performed by a single radiologist, assessing renal stiffness in the lower pole, middle section, and upper pole of each kidney. The mean stiffness values were calculated from at least six measurements per kidney. Laboratory data, including glomerular filtration rate (GFR), serum urea, and creatinine levels, were obtained. Mann–Whitney U and Spearman correlation tests were used for statistical analysis. CKD patients (mean age: 66 years) showed significantly higher cortical stiffness compared with controls (15.6 kPa vs. 5.5 kPa, p < 0.001). A positive correlation was found between stiffness and serum urea/creatinine levels, while an inverse correlation was observed with GFR (p < 0.001). A negative correlation was observed between kidney size and SWE (r = −0.215, p = 0.054), while parenchymal thickness showed a stronger and statistically significant inverse relationship with SWE (r = −0.301, p = 0.006). No significant correlation was found with age or gender (p > 0.05). SWE is a reliable, noninvasive method for assessing renal fibrosis in CKD. With standardization, it could become a valuable tool in routine CKD evaluation.

LIVER SWE and SONOGRAPHER EFECT

 

Concerning our study results, when controlling for all factors (machines, probes, and liver volunteers in time), 17% of inter-observer variability was due to sonographers. 

The differences in scanning procedures reported by healthy liver volunteers may explain why SWE values varied among sonographers, but the reason these scan ning procedures varied among sonographers in the first place is not clear. When sonographers were debriefed after the study, all reported receiving training from the manufacturer. However, there are nuances to the protocol that are likely not included in the training or the consen sus guidelines. For example, some sonographers retain the first 10 SWE values they capture while others care fully review and select their SWE values, retaining some and resampling others. Some sonographers tend to keep the lowest measurements, or the measurements with the least variability. Another area of potential variability is where the ROI is placed within the color box. It is pos sible that these differences in sampling produced a selec tion bias that led to differences in SWE values for some liver volunteers but not others (i.e., poor sampling may be less sensitive to the day-to-day differences within liver volunteers; or contrariwise, better sampling may be more robust to day-to-day differences occurring in liver volun teers). That is, it is possible that by following strict pro tocols, along with multiple resamples throughout a day, a more reliable measure of a person’s SWE may be ob tained. Likewise, less strict adherence to protocols, taken only once, may hide true differences in SWE values and thus appear more reliable than they are.

Conclusion 

 In conclusion, liver shear wave elastography (SWE) values are a function, to some degree, of the sonogra phers obtaining these values. Caution should be used in interpreting SWE values, particularly when relying on strict thresholds for clinical decision making.