Helical computed tomography accurately reports urinary stone composition using attenuation values: in vitro verification using high-resolution micro-computed tomography calibrated to fourier transform infrared microspectroscopy

About 5% of American women and 12% of men will develop a kidney stone at some time in their life, and prevalence has been rising in both sexes. Approximately 80% of stones are composed of calcium oxalate (CaOx) and calcium phosphate (CaP); 10% of struvite (magnesium ammonium phosphate produced during infection with bacteria that possess the enzyme urease), 9% of uric acid (UA); and the remaining 1% are composed of cystine or ammonium acid urate or are diagnosed as drug-related stones. Stones ultimately arise because of an unwanted phase change of these substances from liquid to solid state. Here we focus on the mechanisms of pathogenesis involved in CaOx, CaP, UA, and cystine stone formation, including recent developments in our understanding of related changes in human kidney tissue and of underlying genetic causes, in addition to current therapeutics.

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“…On CT images, they resemble calcium stones, from which they can be distinguished by their lower density (1). On an i.v.…”

Section: Ua Stonesmentioning

confidence: 99%

Kidney stone disease

Coe

Evan

Worcester

2005

Journal of Clinical Investigation

681

527

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“…Combining the analysis of CT numbers with visual assessment of stone morphology using a wide window setting (eg, bone window) substantially improves the accuracy of stone characterization (12). Bellin et al (13) reported in vitro prediction of stone composition with 64%-81% accuracy, whereas Zarse et al (14) demonstrated that highresolution spiral CT yields unique CT numbers for common types of stones if proper window settings are used to localize homogeneous regions within the stones.…”

mentioning

confidence: 99%

Noninvasive Differentiation of Uric Acid versus Non–Uric Acid Kidney Stones Using Dual-Energy CT

et al. 2007

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Rationale and Objectives-To determine the accuracy and sensitivity for dual-energy computed tomography (DECT) discrimination of uric acid (UA) stones from other (non-UA) renal stones in a commercially implemented product.Materials and Methods-Forty human renal stones comprising uric acid (n = 16), hydroxyapatite (n = 8), calcium ox-alate (n = 8), and cystine (n = 8) were inserted in four porcine kidneys (10 each) and placed inside a 32-cm water tank anterior to a cadaver spine. Spiral dual-energy scans were obtained on a dual-source, 64-slice computed tomography (CT) system using a clinical protocol and automatic exposure control. Scanning was performed at two different collimations (0.6 mm and 1.2 mm) and within three phantom sizes (medium, large, and extra large) resulting in a total of six image datasets. These datasets were analyzed using the dual-energy software tool available on the CT system for both accuracy (number of stones correctly classified as either UA or non-UA) and sensitivity (for UA stones). Stone characterization was correlated with micro-CT.Results-For the medium and large phantom sizes, the DECT technique demonstrated 100% accuracy (40/40), regardless of collimation. For the extra large phantom size and the 0.6-mm collimation (resulting in the noisiest dataset), three (two cystine and one small UA) stones could not be classified (93% accuracy and 94% sensitivity). For the extra large phantom size and the 1.2-mm collimation, the dual-energy tool failed to identify two small UA stones (95% accuracy and 88% sensitivity). Conclusions-In an anthropomorphic phantom model, dual-energy CT can accurately discriminate uric acid stones from other stone types. KeywordsKidney stones; renal calculi; dual-energy computed tomography; uric acid; urolithiasis Symptomatic urinary stone disease affects approximately 900,000 persons in the United States each year, resulting in annual medical cost of $5.3 billion. Nephrolithiasis has traditionally been evaluated using plain film radiographic techniques with or without tomography or administration of intravenous contrast for excretory urography. Over recent years, however, computed tomography (CT) has supplanted these traditional techniques because of increased sensitivity, speed, and the lack of intravenous contrast (1 Although state-of-the-art CT provides accurate submillimeter details of the size and location of renal stones (4,5), current routine clinical image analysis does not differentiate stone composition. This is particularly important in the case of uric acid (UA) stones (~10% of cases), because urinary alkalinization can be prescribed to dissolve UA stones and could thereby be initiated at presentation rather than following lengthy metabolic workup. Therefore simple and reliable differentiation of UA versus non-UA stone composition could potentially allow patients with UA stones to avoid invasive interventional urinary procedures for stone removal or external shock wave lithotripsy, both of which are expensive and might result in renal hemorrh...

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“…Stones of size 5 -7 mm have a modest chance (50%) of passage, and those greater than 7 mm almost always require surgical intervention [11].…”

Section: Spontaneous Expulsion Of Giantmentioning

confidence: 99%

Spontaneous Expulsion of Giant Bladder Stone: Case Report

et al. 2018

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Urinary stones of up to 5 mm of diameter are known to pass spontaneously through the urinary tract; whereas those exceeding 7 mm of diameter almost always require surgical intervention. To the best of our knowledge, the option of expectant management for large stones is rarely considered. We report an unusual case of a woman who spontaneously passed out two large bladder stones measuring 70 and 60 mm without having significant pain or bleeding. We find this case striking for the fact that giant bladder stones can expel spontaneously without any surgical manipulations.

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Helical computed tomography accurately reports urinary stone composition using attenuation values: in vitro verification using high-resolution micro-computed tomography calibrated to fourier transform infrared microspectroscopy

Cited by 89 publications

References 19 publications

Kidney stone disease

Kidney stone disease

Noninvasive Differentiation of Uric Acid versus Non–Uric Acid Kidney Stones Using Dual-Energy CT

Spontaneous Expulsion of Giant Bladder Stone: Case Report

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