Can the Hounsfield unit predict the success of medically expulsive therapy?

Do Hounsfield Units have any significance in predicting intra- and postoperative outcomes in retrograde intrarenal surgery using Holmium and Thulium fiber laser? Results from the FLEXible ureteroscopy Outcomes Registry (FLEXOR)

PURPOSE

To evaluate outcomes of flexible ureteroscopy for renal stones by comparing hard versus soft stones based on their attenuation on computed tomography (Hounsfield Units-HU).

METHODS

Patients were divided into two groups according to the type of laser employed [Holmium:YAG (HL) or Thulium fiber laser (TFL)]. Residual fragments (RF) were defined as > 2 mm. Multivariable logistic regression analysis was performed to evaluate factors associated with RF and RF needing further intervention.

RESULTS

4208 patients from 20 centers were included. In whole series, age, recurrent stones, stone size, lower pole stones (LPS), and multiple stones were predictors of RF at multivariable analysis and LPS and stone size with RF requiring further treatment. HU and TFL were associated with lesser RF and RF requiring an additional treatment. In HU < 1000 stones, recurrent stones, stone size, and LPS were predictors of RF at multivariable analysis, whereas TFL was less likely associated with RF. Recurrent stones, stone size, and multiple stones were predictors of RF requiring further treatment, while LPS and TFL were associated with lesser RF requiring further treatment. In HU ≥ 1000 stones, age, stone size, multiple stones, and LPS were predictors of RF at multivariable analysis, while TFL was less likely associated with RF. Stone size and LPS were predictors of RF requiring further treatment, whereas TFL was associated with RF requiring further treatment.

CONCLUSION

Stone size, LPS, and use of HL are predictors of RF after RIRS for intrarenal stones regardless of stone density. HU should be considered an important parameter in predicting SFR.

Can the Hounsfield unit predict the success of medical expulsive therapy using silodosin in 4- to 10-mm distal ureteral stones?

OBJECTIVE

We aimed to investigate the predictive ability of the Hounsfield unit (HU) on non-contrast computed tomography (NCCT) for the success of medical expulsive therapy (MET) using silodosin in distal ureteric stones of 4-10 mm.

METHODOLOGY

The data of patients who underwent MET were retrospectively screened. The patients were divided into two groups as Groups 1 and 2 depending on the presence or absence of stone expulsion, respectively. In addition to HU calculated using the NCCT images, state of the collecting systems, daily fluid intake, number of emergency department visits, and number of pain attacks were compared.

RESULTS

A total of 88 patients were included in the study. Sixty-four patients (72.7%) expelled the stone after MET while the treatment was not successful in 24 patients (27.3%). The stone area was significantly larger in Group 2 (28.4 ± 15.7 mm² vs 46.8 ± 16.1 mm² ; P < .001). NCCT-HU was calculated as 542.5 ± 256.8 for Group 1 and 873.1 ± 335.2 for Group 2, indicating a significant difference (P < .001). The mean number of pain attacks was 1.5 ± 1.2 in Group 1 and 2.2 ± 1.4 in Group 2 (P = .048). The number of visits to the emergency department significantly differed between Groups 1 and 2 (1.1 ± 1.0 and 1.8 ± 1.3, respectively; P = .010).

CONCLUSIONS

In this study, HU and stone area values calculated on NCCT were found to be effective factors in predicting the treatment success for MET. Therefore, we consider that it would be useful to consider these parameters in the selection of an appropriate treatment for distal ureteric stones.

Can ureteral wall thickness (UWT) be used as a potential parameter for decision-making in uncomplicated distal ureteral stones 5-10 mm in size? A prospective study

OBJECTIVE

To evaluate the correlation between ureteral wall thickness (UWT) and stone passage (SP) and its cut-off value in distal uncomplicated ureteral stones.

PATIENTS AND METHODS

In the prospective study from January 2019 to January 2020 at a tertiary care hospital, we reviewed 212 patients aged above 18 years with single, symptomatic, radiopaque, and distal ureteric stone sized 5-10 mm, who were treated with MET (Silodosin 8 mg once daily) until SP or a maximum of 4 weeks. There were 2 groups: responders and non-responders. Demographic data of the patients and all stone radiological parameters including stone size, laterality, density, UWT, the diameter of the ureter proximal to the stone (PUD), and the degree of hydronephrosis were recorded and compared between the 2 groups.

RESULTS

There were 126 (59.4%) in the responder group and 86 (40.6%) in the non-responder group. On univariate analysis, gender, stone density, stone size, PUD, UWT, and the degree of hydronephrosis were significant factors for stone passage. However, using multivariate analysis, only UWT and the degree of hydronephrosis were significant. ROC analysis showed that 3.75 mm is the cut-off value for UWT, with 86% and 87.3% sensitivity and specificity, respectively.

CONCLUSIONS

UWT and hydronephrosis can be used as potential predictors for SP and can help with decision-making in patients with uncomplicated 5-10 mm lower ureteric stones.

Hounsfield unit and its correlation with spontaneous expulsion of lower ureteric stone

Background:

Hounsfield unit (HU) is the measure of stone density, and is utilized in the predetermination of type of stone. The purpose of this study was to identify some factors in noncontrast computed tomography (NCCT) of kidney, ureter, and bladder (KUB) that are easily extractable and can be used to determine the outcome of expectant management.

Methods:

All patients 18–50 years of age who presented with flank pain and diagnosed as having lower ureteric calculi of size 5–10 mm by NCCT KUB were included in the study. HU of stone was calculated from the mean HU at three different regions of interest. We prescribed tamsulosin for 4 weeks as medical expulsive therapy. We divided the patients into two groups: group A included patients with successful expulsion of stone, and group B included patients who failed to pass stone. We compared age, gender, laterality, stone size in axial and coronal section of NCCT, HU of stone, blood urea, creatinine, and renal parenchymal thickness.

Results:

A total of 180 patients with lower ureteric calculus were included in the study. The mean age of patients was 34 years, with male:female ratio of 2.3:1. Of these 180 patients, 119 (66%) successfully expelled the stone and were included in group A, with the remaining 61 (34%) forming group B. In univariate analysis, longitudinal diameter of stone (p < 0.001), transverse diameter of stone (p < 0.001) and high HU (p < 0.001) were significantly associated with failure of expulsion. However, in multivariate analysis only longitudinal diameter of stone (p < 0.001) differed significantly among groups. Differences in HU (p = 0.179) and transverse diameter of stone (p = 0.108) did not reach significance level.

Conclusions:

Lower ureteric calculi are definitely amenable to conservative management. Longitudinal diameter of stone can be a useful parameter; however, HU and its derivatives cannot be used as a predictor of outcome.

Assessment of factors affecting the spontaneous passage of lower ureteric calculus on the basis of lower ureteric calculus diameter, density, and plasma C- reactive protein level

Introduction:

The study aimed to evaluate the factors which affect the spontaneous passage of lower ureteric calculus on the basis of noncontrast computed tomography kidneys, ureters, and bladder (NCCT KUB) stone diameter, stone density, and plasma C-reactive protein (CRP) level.

Materials and Methods:

We conducted a prospective study of 200 patients with lower ureteric calculus 5–10 mm in size, from October 2015 to December 2016. All patients underwent NCCT KUB region with a 5 mm axial and reformatted coronal section. Edema just above the calculus and rim sign at the level of calculus and density of calculus is evaluated. Only scan with isolated, unilateral, solitary ureteric calculus was included in the final analysis and monitored up to 4 weeks, and plasma CRP is estimated in all patients to determine the clinical outcome.

Results:

A total of 200 patients (145 males, 55 females; mean age ± standard deviation, 34.73 ± 10.29) were included in the study. Lower ureteric calculus between 5–7 mm passed in 70% and 7–10 mm passed in 40%. There was 18% underestimation of maximum stone diameter in axial plane as compared to coronal plane. For spontaneous passage of calculus, craniocaudal (CC) diameter is more reliable then axial in NCCT. Rim sign and edema is absent in 64% of those passed spontaneous calculus. CRP level more than 2.45 mg/dl has low spontaneous expulsion rate. The stone with different HU passes through the ureter with same rate.

Conclusion:

Plasma CRP level and CC diameter and absence of rim sign on NCCT KUB are more reliable factors then density for spontaneous passage of ureteric calculus.