The skin-to-calyx distance measured by renal ct scan and ultrasound

Int Braz J Urol. Mar-Apr 2014;40(2):212-9. doi: 10.1590/S1677-5538.IBJU.2014.02.11.

Abstract

Purpose: We developed a stereotactic device to guide the puncture for percutaneous nephrolithotripsy, which uses the distance from the target calyx to its perpendicular point on skin (SCD) to calculate the needle´s entry angle. This study seeks to validate the use of measurements obtained by ultrasound (US) and computerized tomography (CT) for needle´s entry angle calculation and to study factors that may interfere in this procedure.

Materials and methods: Height, weight, abdominal circumference, CT of the urinary tract in dorsal decubitus (DD) and ventral decubitus (VD), and US of the kidneys in VD were obtained from thirty-five renal calculi patients. SCD obtained were compared and correlated with body-mass index (BMI).

Results: BMI was 28.66 ± 4.6 Kg/m2. SCD on CT in DD was 8.40 ± 2.06cm, in VD was 8.32 ± 1.95cm, in US was 6.74 ± 1.68cm. SCD measured by US and CT were statistically different (p < 0.001), whereas between CT in DD and VD were not. SCD of the lower calyx presented moderate correlation with BMI.

Conclusion: SCD obtained by CT in ventral and dorsal decubitus may be used for calculation of the needle´s entry angle. SCD obtained by US cannot be used. A rule for the correlation between BMI and the SCD could not be determined.

Publication types

  • Validation Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Analysis of Variance
  • Body Mass Index
  • Equipment Design
  • Female
  • Humans
  • Kidney Calices / anatomy & histology*
  • Kidney Calices / diagnostic imaging
  • Male
  • Middle Aged
  • Reference Values
  • Reproducibility of Results
  • Skin / anatomy & histology*
  • Skin / diagnostic imaging
  • Stereotaxic Techniques / instrumentation*
  • Supine Position
  • Tomography, X-Ray Computed / instrumentation*
  • Tomography, X-Ray Computed / methods
  • Ultrasonography
  • Waist Circumference
  • Young Adult