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Waqas M et al, 2017: Non-Contrast Computed Tomography Scan Based Parameters of Ureteric Stones Affecting the Outcome of Extracorporeal Shock Wave Lithotripsy.

Waqas M, Ayaz Khan M, Waqas Iqbal M, Akbar MK, Saqib IU, Akhter S.
Department of Urology, Shifa International Hospital, Islamabad, Pakistan.
Department of Plastic Surgery, Shifa International Hospital, Islamabad, Pakistan.

Abstract

OBJECTIVE : To compare the non-contrast computed tomography (NCCT) scan-based parameters of ureteric stones affecting the outcome of extracorporeal shock wave lithotripsy (ESWL).
MATERIALS AND METHODS: We retrospectively evaluated the pre-procedure NCCT of 74 patients who had ESWL for solitary ureteric calculi of 5-20 mm in diameter. We assessed the age, sex, basal metabolic index (BMI), laterality, location, presence of double 'J' (DJ) stent, skin to stone distance (SSD), stone maximum diameter, Hounsfield unit (HU), Hounsfield density (HD), area, and volume. All those who had no stone on follow-up imaging within 30 days were declared successful while those who had residual stone were declared failures.
RESULTS: The overall success rate was 78% (58/74). Sixty (81.1%) patients were male. The success of ESWL was correlated with lower SSD, Hounsfield units (HU) and Hounsfield density (HD). However, in multivariate analysis, SSD, Hounsfield unit, and stone area showed correlation with success of procedure but Hounsfield density failed to show correlation. The success rate in patients with stone HU <500, 500-1000 and >1000 were 93.9%, 69%, and 58.3%, respectively. Patients with lower BMI (30 kg/m2) and higher HD (>76 HU/mm).
CONCLUSION: BMI, SSD, stone Hounsfield units and Hounsfield unit density were strong predictors of outcome of ESWL for ureteric stone.

Cureus. 2017 May 5;9(5):e1227. doi: 10.7759/cureus.1227.

 

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Comments 1

Hans-Göran Tiselius on Monday, 11 September 2017 09:16

Numerous reports have summarized the importance of factors that might predict the outcome of ESWL. In this report from Pakistan the authors looked at data obtained from NCCT-examinations carried out in 74 patients. The measurements were compared with results of ESWL success. It is of note that as many as 80% of the patients had their stones in the proximal ureter. This is opposite to the statement in the Introduction that only 25% of ureteral stones were located at that level.

The mean number of ESWL-sessions was approximately 1.5 both for patients with and without successful treatment.

The conclusions drawn were that SSD, HU-units, HU-density and BMI were significantly different between those with and without success. The multivariate analysis emphasized the importance of SSD, HU and stone surface area.

In view of the demonstrated importance of SSD, it seems desirable to add to modern lithotripters the possibility to measure this distance in line with the shock wave path, rather that to use an average of measurements in three different angles on the NCCT. Although it might be late to know this distance when the patient is already on the lithotripter table, this knowledge nevertheless might indicate that a higher than normal energy level might be useful.

Numerous reports have summarized the importance of factors that might predict the outcome of ESWL. In this report from Pakistan the authors looked at data obtained from NCCT-examinations carried out in 74 patients. The measurements were compared with results of ESWL success. It is of note that as many as 80% of the patients had their stones in the proximal ureter. This is opposite to the statement in the Introduction that only 25% of ureteral stones were located at that level. The mean number of ESWL-sessions was approximately 1.5 both for patients with and without successful treatment. The conclusions drawn were that SSD, HU-units, HU-density and BMI were significantly different between those with and without success. The multivariate analysis emphasized the importance of SSD, HU and stone surface area. In view of the demonstrated importance of SSD, it seems desirable to add to modern lithotripters the possibility to measure this distance in line with the shock wave path, rather that to use an average of measurements in three different angles on the NCCT. Although it might be late to know this distance when the patient is already on the lithotripter table, this knowledge nevertheless might indicate that a higher than normal energy level might be useful.
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