Tools to Improve the Accuracy of Kidney Stone Sizing with Ultrasound

Dunmire, Barbrina; Lee, Franklin C.; Hsi, Ryan S.; Cunitz, Bryan W.; Paun, Marla; Bailey, Michael R.; Sorensen, Mathew D.; Harper, Jonathan D.

doi:10.1089/end.2014.0332

Cited by 36 publications

(36 citation statements)

References 15 publications

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“…5,7,10 The average overestimation reported previously and here is on the order of 1.5 to 2.0 mm. Conventional ray line imaging is more accurate in measuring stone size than spatial compound imaging, but when measuring the stone directly the most accurate results were with harmonic imaging.…”

Section: Discussionsupporting

confidence: 49%

“…Recent literature has shown that system settings and US imaging modality can affect the appearance of the hyperechoic boundaries and, thus, the measured stone size. 7 However, the edges of the acoustic shadow do not undergo the same distortion as the hyperechoic stone. In this study we investigated the acoustic shadow width as an alternative measure of stone size.…”

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confidence: 99%

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Use of the Acoustic Shadow Width to Determine Kidney Stone Size with Ultrasound

et al. 2016

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Purpose Ultrasound is known to overestimate kidney stone size. We explored measuring the acoustic shadow behind kidney stones combined with different ultrasound imaging modalities to improve stone sizing accuracy. Materials and Methods A total of 45 calcium oxalate monohydrate stones were imaged in vitro at 3 different depths with the 3 different ultrasound imaging modalities of conventional ray line, spatial compound and harmonic imaging. The width of the stone and the width of the acoustic shadow were measured by 4 operators blinded to the true size of the stone. Results Average error between the measured and true stone width was 1.4 ± 0.8 mm, 1.7 ± 0.9 mm, 0.9 ± 0.8 mm for ray line, spatial compound and harmonic imaging, respectively. Average error between the shadow width and true stone width was 0.2 ± 0.7 mm, 0.4 ± 0.7 mm and 0.0 ± 0.8 mm for ray line, spatial compound and harmonic imaging, respectively. Sizing error based on the stone width worsened with greater depth (p <0.001) while the sizing error based on the shadow width was independent of depth. Conclusions Shadow width was a more accurate measure of true stone size than a direct measurement of the stone in the ultrasound image (p <0.0001). The ultrasound imaging modality also impacted the measurement accuracy. All methods performed similarly for shadow size while harmonic imaging was the most accurate stone size modality. Overall 78% of the shadow sizes were accurate to within 1 mm, which is similar to the resolution obtained with clinical computerized tomography.

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Section: Discussionsupporting

confidence: 49%

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confidence: 99%

Use of the Acoustic Shadow Width to Determine Kidney Stone Size with Ultrasound

et al. 2016

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“…Taking this research even further, our group is working on a stone-specific mode for ultrasonography termed ‘S-mode’ to harness the inherent differences between stones and their surrounding tissues 42,44 . Ultrasonographic greyscale imaging is currently optimized for visualization and differentiation of soft tissues.…”

Section: Ultrasonographymentioning

confidence: 99%

An overview of kidney stone imaging techniques

2016

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Kidney stone imaging is an important diagnostic tool and initial step in deciding which therapeutic options to use for the management of kidney stones. Guidelines provided by the American College of Radiology, American Urological Association, and European Association of Urology differ regarding the optimal initial imaging modality to use to evaluate patients with suspected obstructive nephrolithiasis. Noncontrast CT of the abdomen and pelvis consistently provides the most accurate diagnosis but also exposes patients to ionizing radiation. Traditionally, ultrasonography has a lower sensitivity and specificity than CT, but does not require use of radiation. However, when these imaging modalities were compared in a randomized controlled trial they were found to have equivalent diagnostic accuracy within the emergency department. Both modalities have advantages and disadvantages. Kidney, ureter, bladder (KUB) plain film radiography is most helpful in evaluating for interval stone growth in patients with known stone disease, and is less useful in the setting of acute stones. MRI provides the possibility of 3D imaging without exposure to radiation, but it is costly and currently stones are difficult to visualize. Further developments are expected to enhance each imaging modality for the evaluation and treatment of kidney stones in the near future. A proposed algorithm for imaging patients with acute stones in light of the current guidelines and a randomized controlled trial could aid clinicians.

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“…7 This includes reducing the use of smoothing algorithms and the compression of high signal-intensity regions to improve visualization and sharpen contrast at the edge of stones and in the posterior shadow. 8,9 These techniques have been incorporated into an US imaging modality, coined the stone-specific mode, or S-mode.…”

Section: Introductionmentioning

confidence: 99%

Stone-Mode Ultrasound for Determining Renal Stone Size

May

Haider

Dunmire

et al. 2016

Journal of Endourology

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Purpose: The purpose of this study was to measure the accuracy of stone-specific algorithms (S-mode) and the posterior acoustic shadow for determining kidney stone size with ultrasound (US) in vivo. Materials and Methods: Thirty-four subjects with 115 renal stones were prospectively recruited and scanned with S-mode on a research US system. S-mode is gray-scale US adjusted to enhanced stone contrast and resolution by minimizing compression and averaging, and increasing line density and frequency. Stone and shadow width were compared with a recent CT scan and, in 5 subjects with 18 stones, S-mode was compared with a clinical US system. Results: Overall, 84% of stones identified on CT were detected on S-mode and 66% of these shadowed. Seventy-three percent of the stone measurements and 85% of the shadow measurements were within 2 mm of the size on CT. A posterior acoustic shadow was present in 89% of stones over 5 mm versus 53% of stones under 5 mm. S-mode visualized 78% of stones, versus 61% for the clinical system. S-mode stone and shadow measurements differed from CT by 1.6 -1.0 mm and 0.8 -0.6 mm, respectively, compared with 2.0 -1.5 mm and 1.6 -1.0 mm for the clinical system. Conclusions: S-mode offers improved visualization and sizing of renal stones. With S-mode, sizing of the stone itself and the posterior acoustic shadow were similarly accurate. Stones that do not shadow are most likely <5 mm and small enough to pass spontaneously.

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Tools to Improve the Accuracy of Kidney Stone Sizing with Ultrasound

Cited by 36 publications

References 15 publications

Use of the Acoustic Shadow Width to Determine Kidney Stone Size with Ultrasound

Use of the Acoustic Shadow Width to Determine Kidney Stone Size with Ultrasound

An overview of kidney stone imaging techniques

Stone-Mode Ultrasound for Determining Renal Stone Size

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