Accurate Determination of Chemical Composition of Urinary Calculi by Spiral Computerized Tomography

Mostafavi, Mohammad; Ernst, Randy D.; Saltzman, Brian

doi:10.1016/s0022-5347(01)63698-x

Cited by 204 publications

(82 citation statements)

References 17 publications

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“…More recently, Mostafavi et al [18] reported that the best single CT parameter for assessing the chemical composition of stones was the absolute CT-attenuation value at 120 kV rather than at 80 kV, a result that is not confirmed by our data. They demonstrated in an in vitro setting that the absolute CT-attenuation value at 120 kV was able to identify uric acid, struvite and calcium oxalate stones but was unable to distinguish between calcium oxalate and brushite stones and struvite and cystine stones.…”

Section: Discussioncontrasting

confidence: 95%

“…However, cystine and uric acid stones were identified in one study [13], but not in another [12]. Mostafavi et al [18] were able to determine accurately at dual kilovoltage the chemical composition of urinary tract calculi by scanning the whole urinary tract with 1-mm collimation and a pitch of 1:1, which is impractical in daily practice. More recently, it was shown in vitro that visualization of stone structure was greatly enhanced using bone windows and a narrow slice width [19].…”

Section: Introductionmentioning

confidence: 99%

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Helical CT evaluation of the chemical composition of urinary tract calculi with a discriminant analysis of CT-attenuation values and density

et al. 2004

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The aim of this study was to evaluate the efficacy of helical CT using a combination of CT-attenuation values and visual assessment of stone density as well as discriminant linear analysis to predict the chemical composition of urinary calculi. One hundred human urinary calculi were obtained from a stone-analysis laboratory and placed in 20 excised pig kidneys. They were scanned at 80, 120 and 140 kV with 3-mm collimation. Average, highest and lowest CT-attenuation values and CT variability were recorded. The internal calculus structure was assessed using a wide window setting, and visual assessment of stone density was recorded. A stepwise discriminant linear analysis was performed. The following three variables were discriminant: highest CT-attenuation value, visual density, and highest CT-attenuation value/area ratio, all at 80 kV. The probability of correctly classifying stone composition with these three variables was 0.64, ranging from 0.54 for mixed calculi to 0.69 for pure calculi. The probabilities of correctly classifying calculus composition were: 0.91 for calcium oxalate monohydrate and brushite, 0.89 for cystine, 0.85 for uric acid, 0.11 for calcium oxalate dihydrate, 0.10 for hydroxyapatite, and 0.07 for struvite calculi. When the first two ranks of highest probability for the accurate classification of each calculus type were taken into account, 81% of the calculi were correctly classified. Assessment at 80 kV of the highest CT-attenuation value, visual density and the highest CT-attenuation value/area ratio accurately predicts the chemical composition of 64-81% of urinary calculi. When the first two ranks of highest probability for the accurate classification of each calculus type were taken into account, all cystine, calcium oxalate monohydrate and brushite calculi were correctly classified.

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Section: Discussioncontrasting

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Helical CT evaluation of the chemical composition of urinary tract calculi with a discriminant analysis of CT-attenuation values and density

et al. 2004

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“…Several previous studies have shown that a certain prediction of the chemical composition can be made by analyzing the CT attenuation of the calculus if the CT system is well calibrated [9][10][11]. However, despite promising in vitro results, the reproducibility of the results in vivo has not been found satisfactory [11].…”

Section: Introductionmentioning

confidence: 99%

Dual-energy CT for the characterization of urinary calculi: In vitro and in vivo evaluation of a low-dose scanning protocol

et al. 2009

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The efficiency and radiation dose of a low-dose dual-energy (DE) CT protocol for the evaluation of urinary calculus disease were evaluated. A low-dose dual-source DE-CT renal calculi protocol (140 kV, 46 mAs; 80 kV, 210 mAs) was derived from the single-energy (SE) CT protocol used in our institution for the detection of renal calculi (120 kV, 75 mAs). An Alderson-Rando phantom was equipped with thermoluminescence dosimeters and examined by CT with both protocols. The effective doses were calculated. Fifty-one patients with suspected or known urinary calculus disease underwent DE-CT. DE analysis was performed if calculi were detected using a dedicated software tool. Results were compared to chemical analysis after invasive calculus extraction. An effective dose of 3.43 mSv (male) and 5.30 mSv (female) was measured in the phantom for the DE protocol (vs. 3.17/4.57 mSv for the SE protocol). Urinary calculi were found in 34 patients; in 28 patients, calculi were removed and analyzed (23 patients with calcified calculi, three with uric acid calculi, one with 2,8-dihyxdroxyadenine-calculi, one patient with a mixed struvite calculus). DE analysis was able to distinguish between calcified and non-calcified calculi in all cases. In conclusion, dual-energy urinary calculus analysis is effective also with a low-dose protocol. The protocol tested in this study reliably identified calcified urinary calculi in vivo.

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“…We hypothesized that the density of opacified calyces should be uniformly more than 150 HU but less than 250 HU because published CT measured calculus densities have varied between 250-1,600 Hounsfield units (HU) [3][4][5][6][7][8], and unpublished data from our department have shown that the renal parenchyma measures around 100 HU in the excretory phase. Initial studies of CT pyelography using slightly different techniques [9,10] have been promising, and in this retrospective study we critically analyze the reproducibility of CT pyelography in routine use.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional CT pyelography for planning of percutaneous nephrostolithotomy: accuracy of stone measurement, stone depiction and pelvicalyceal reconstruction

et al. 2009

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Retrospective evaluation of computed tomographic (CT) pyelography before percutaneous nephrostolithotomy (PCNL). Twenty patients with renal calculi underwent CT pyelography using a dedicated protocol. Calculus size, uniformity of contrast excretion and accuracy of calculus and pelvicalyceal (PC) system reconstructions were scored and compared on axial and coronal maximum intensity projections (MIP) and volume reconstructions (VRmovie loops). After contrast medium administration, the size of calculi is accurate on axial images, but underestimated on coronal studies: mean 14.7 mm vs. 14.4 mm (axial) and 17.2 mm vs. 16.1 mm (coronal) for measurements before and after enhancement, respectively (p = 0.11 and 0.03). Uniform contrast medium excretion (median 228 HU; 95% CI 209-266 HU) was sufficiently lower than calculus density (median 845 HU; 95% CI 457-1,193 HU) for precise calculus and pelvicalyceal reconstructions in 87% and 85%, respectively. Coronal MIP scans were rated best for calculus depiction (mean score 2.68 vs. 2.50 and 2.41 for coronal, axial and VRs, respectively; p = 0.14) and VR studies best for PC anatomy (mean score 4.4 vs. 3.73 and 2.89 for VR, coronal and axial studies, respectively; p = <0.0001). Three-dimensional CT pyelography can accurately demonstrate calculus position and spatial relationships of the collecting system before PCNL.

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Accurate Determination of Chemical Composition of Urinary Calculi by Spiral Computerized Tomography

Abstract: This study demonstrates that the chemical composition of urinary calculi can be accurately determined by CT scanning in an in vitro setting.

Cited by 204 publications

References 17 publications

Helical CT evaluation of the chemical composition of urinary tract calculi with a discriminant analysis of CT-attenuation values and density

Helical CT evaluation of the chemical composition of urinary tract calculi with a discriminant analysis of CT-attenuation values and density

Dual-energy CT for the characterization of urinary calculi: In vitro and in vivo evaluation of a low-dose scanning protocol

Three-dimensional CT pyelography for planning of percutaneous nephrostolithotomy: accuracy of stone measurement, stone depiction and pelvicalyceal reconstruction

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