The effect of gas composition on the color Doppler ultrasound twinkling artifact in kidney stones
Open Access
- Author:
- Brownstead, Laura
- Graduate Program:
- Acoustics (MS)
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 28, 2023
- Committee Members:
- Julianna Simon, Thesis Advisor/Co-Advisor
Andrea P. Arguelles, Committee Member
Andrew Barnard, Program Head/Chair
Yun Jing, Committee Member - Keywords:
- kidney stones
twinkling
doppler power
ultrasound
clinical study
ambient gas
urinary tract
kidney - Abstract:
- When kidney stones travel through the urinary tract, they sometimes become lodged in the ureter and can cause severe pain, nausea, and infection. Kidney stones are often diagnosed when they attempt to pass, and those who repeatedly form stones may receive routine scans to detect and monitor additional stones. However, ultrasound scans lack the sensitivity and specificity of other kidney stone detection methods, like X-ray and computed tomography. The color Doppler ultrasound twinkling artifact, a signal unique to ultrasound scans, increases the specificity of kidney stone detection. However, twinkling only appears in about 60% of stones, prompting investigations to enhance the consistency of twinkling to make it a valuable clinical tool. Based on previous work, environmental gas composition may alter the occurrence and strength of the twinkling artifact. Predominant published theories attribute twinkling to trapped surface microbubbles, whose gas content may change in response to environmental gas composition. The current work investigates how oxygen, nitrogen, and carbon dioxide affect twinkling from ex vivo kidney stones and how breathing oxygen affects twinkling from in vivo kidney stones. Twinkling from ex vivo kidney stones was measured in elevated oxygen, nitrogen, and carbon dioxide environments. The changes in power from each gas were not statistically significant, though 3D maps detail twinkling features that align with predominant theories. Averaged twinkling increased 35 ± 76% when oxygen concentration increased from 9.1 mg/L to 12.9 mg/L, increased 125 ± 102% from 8.7 mg/L to 13.5 mg/L, and increased 93 ± 43% from 5.2 mg/L to 20.0 mg/L. Averaged twinkling increased 133 ± 59% from 14 ppm carbon dioxide to 28 ppm, and increased 79 ± 140% from 0 ppm nitrate to 60 ppm nitrate. However, no gas study was ii statistically significant (p=0.17, p=0.08, p=0.11; W=123.0, p=0.126; p=0.17, respectively). Summed twinkling increased by 34 ± 70%, by 134 ± 113%, and by 93 ± 43% in the three oxygen studies, by 132 ± 59% in carbon dioxide, and by 34 ± 70% in nitrogen; however, none was statistically significant (p=0.17, p=0.08, p=0.11; W=123.0, p=0.126; p=0.17, respectively). Twinkling from in vivo stones was measured before and after human subjects breathed pure oxygen for fifteen minutes. Breathing oxygen increased background-normalized averaged twinkling by 30 ± 64% and summed twinkling by 18 ± 63%; however, neither was statistically significant (averaged: p=0.18, summed: p=0.27). Twinkling from background reference boxes decreased by 1 ± 19% from baseline to oxygenated, so non-normalized data was also evaluated. When power levels were not normalized to a depth-matched reference level, averaged twinkling increased by 28 ± 61% and summed twinkling increased by 33 ± 63%, which approached statistical significance (averaged: p=0.05, summed: p=0.07). Although in vivo and ex vivo studies show no significant twinkling change from environmental gas changes, studies with oxygen approach significance most closely. Since oxygen did not prevent twinkling in any stones, it may cause more stones to twinkle when scanned with ultrasound.