Low-Dose Unenhanced Computed Tomography with Iterative Reconstruction for Diagnosis of Ureter Stones

Hoon, Byung; Chang, In Ho; Lee, Dong Hoon; Park, Sung Bin; Kim, Kyung Do; Moon, Young Tae; Hur, Taekyu

doi:10.3349/ymj.2018.59.3.389

Cited by 10 publications

(11 citation statements)

References 20 publications

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“…Dual energy XCT is often used with contrast agents which include elements such as iodine and barium, although non-contrast scans are current practice as well. [16] Elements with K edges in the range of medical x-rays would likely require one or more additional tube voltages, or a scan with a limited spectral range, to provide a complete picture of the patient or sample.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, Lalonde and Bouchard [9] suggested that two tube voltages were required for soft tissue and an additional two tube voltages could be used for bony tissue, leading to a suggestion that measurements at three or four tube voltages would have an advanges over dual energy XCT for natural (i.e., not contrast enhanced) tissue. [16] Here, we will differ somewhat from previous studies in looking directly at the the intrinsic dimensionality of the Hounsfield unit measurements as a function of tube voltage instead of considering the intrinsic dimensionality of the x-ray cross sections themselves.…”

Section: Introductionmentioning

confidence: 99%

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Preliminary X-ray CT investigation to link Hounsfield unit measurements with the International System of Units (SI)

et al. 2018

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PurposeThis paper lays the groundwork for linking Hounsfield unit measurements to the International System of Units (SI), ultimately enabling traceable measurements across X-ray CT (XCT) machines. We do this by characterizing a material basis that may be used in XCT reconstruction giving linear combinations of concentrations of chemical elements (in the SI units of mol/m3) which may be observed at each voxel. By implication, linear combinations not in the set are not observable.Methods and materialsWe formulated a model for our material basis with a set of measurements of elemental powders at four tube voltages, 80 kV, 100 kV, 120 kV, and 140 kV, on a medical XCT. The samples included 30 small plastic bottles of powders containing various compounds spanning the atomic numbers up to 20, and a bottle of water and one of air. Using the chemical formulas and measured masses, we formed a matrix giving the number of Hounsfield units per (mole per cubic meter) at each tube voltage for each of 13 chemical elements. We defined a corresponding matrix in units we call molar Hounsfield unit (HU) potency, the difference in HU values that an added mole per cubic meter in a given voxel would add to the measured HU value. We built a matrix of molar potencies for each chemical element and tube voltage and performed a singular value decomposition (SVD) on these to formulate our material basis. We determined that the dimension of this basis is two. We then compared measurements in this material space with theoretical measurements, combining XCOM cross section data with the tungsten anode spectral model using interpolating cubic splines (TASMICS), a one-parameter filter, and a simple detector model, creating a matrix similar to our experimental matrix for the first 20 chemical elements. Finally, we compared the model predictions to Hounsfield unit measurements on three XCT calibration phantoms taken from the literature.ResultsWe predict the experimental HU potency values derived from our scans of chemical elements with our theoretical model built from XCOM data. The singular values and singular vectors of the model and powder measurements are in substantial agreement. Application of the Bayesian Information Criterion (BIC) shows that exactly two singular values and singular vectors describe the results over four tube voltages. We give a good account of the HU values from the literature, measured for the calibration phantoms at several tube voltages for several commercial instruments, compared with our theoretical model without introducing additional parameters.ConclusionsWe have developed a two-dimensional material basis that specifies the degree to which individual elements in compounds effect the HU values in XCT images of samples with elements up to atomic number Z = 20. We show that two dimensions is sufficient given the contrast and noise in our experiment. The linear combination of concentrations of elements that can be observed using a medical XCT have been characterized, providing a material basis for use in dual-energy recon...

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Preliminary X-ray CT investigation to link Hounsfield unit measurements with the International System of Units (SI)

et al. 2018

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“…Taking all the 17 studies into consideration, the sensitivity estimates ranged from 0.70 to 0.98 and the speci city estimates ranged from 0.39 to 1.00. The result of heterogeneity test showed that 3 studies [20,26,30] have obvious heterogeneity (Supplemental Fig. 4).…”

Section: Data Extraction and Meta-analysismentioning

confidence: 99%

“…full-text articles were later excluded due to these reasons: retrospective studies (n = 4), without speci c number of TP, FP, FN, TN(n = 3), without effective dose (n = 1). Finally, A total of 17 unique articles with 1,761 patients (mean age: 46.40) and 2,053 stones were included [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] for the quantitative analysis. 13 studies [14][15][16][17][18][19][20][21][22][23][24][25][26] were included in the former studies [10][11], and 4 studies [27][28][29][30] were new studies.…”

Section: Literature Search and Study Selectionmentioning

confidence: 99%

The Diagnostic Accuracy of Low-Dose Computed Tomography in Diagnosing Urolithiasis: A Systematic Review and Meta-Analysis

Liang

Chang

Wang

et al. 2020

Preprint

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Background: Urolithiasis is a prevalent health issue all over the world,To evaluate the diagnostic accuracy of low-lose computed tomography(LDCT) for detecting urolithiasis. Methods: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was followed. PubMed, EMBASE and The Cochrane Library were searched for original diagnostic studies to identify all relevant studies published prior to May 2020. The index test was LDCT, and the reference standards were comprehensive diagnosis or standard-dose CT (SDCT). Results: 17 studies with 1,761 patients and 2,053 stones were included for the quantitative analysis. The pooled sensitivity was 0.95 (95%CI: 0.93-0.97) in patient-based studies and 0.86 (95%CI: 0.76-0.93) in urolithiasis-based studies. The pooled specificity of LDCT were 0.97 (95%CI: 0.95-0.99) in patient-based studies and 0.98 (95%CI: 0.63-1.00) in urolithiasis-based studies. The Fagan nomogram of LDCT for diagnosis of urolithiasis showed that the probability of urolithiasis is 98% if the LDCT scan is positive and 6% if the LDCT scan is negative. The likelihood ratio plot showed that the summary positive pooled likelihood ratio (LRP) and negative likelihood ratio (LRN) for LDCT was in the left upper quadrant(LUQ) area. Conclusions: LDCT has excellent diagnostic value in urolithiasis. LDCT can detect the urolithiasis specifically, but is limited to differentiate the contents of the stones.

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“…Given that non-contrast computed tomography (NCCT) has become the gold standard of diagnosing urinary stones [10,11], many groups have focused on the relation between Hounsfield units (HU), especially mean stone density (MSD), and urinary stone composition or treatment outcome [12]. In addition to MSD, the stone heterogeneity index (SHI), also known as standard deviation of HU, and the variant coefficient of stone density (VCSD) have emerged as potential therapeutic gauges [13,14].…”

Section: Introductionmentioning

confidence: 99%

Predictors of Uric Acid Stones: Mean Stone Density, Stone Heterogeneity Index, and Variation Coefficient of Stone Density by Single-Energy Non-Contrast Computed Tomography and Urinary pH

Kim

Chung

et al. 2019

JCM

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We analyzed the capacities of pertinent parameters (determined by single-energy non-contrast computed tomography [NCCT]) and urinary pH to predict uric acid stones. We reviewed the medical records of 501 patients whose stones were removed surgically or passed spontaneously between December 2014 and April 2016. Qualifying participants (n = 420) were stratified by the nature of the stone (calcium oxalate, uric acid, or infectious). Based on NCCT, we determined maximal stone length (MSL), mean stone density (MSD), and stone heterogeneity index (SHI) using Hounsfield units (HU) and calculated the variant coefficient of stone density (VCSD = SHI/MSD × 100). Urinary pH was also ascertained. Mean patient age was 55.55 ± 15.46 years. MSD (448.59 ± 173.21 HU), SHI (100.81 ± 77.37 HU), and VCSD (22.58 ± 10.55) proved to be significantly lower in uric acid versus other types of stones, as did urinary pH (5.33 ± 0.56; all p < 0.001). Receiver operating characteristic (ROC) curves depicting predictability of uric acid stones yielded area under ROC curve (AUC) values for MSD, SHI, VCSD, and urinary pH of 0.806 (95% CI: 0.761–0.850), 0.893 (95% CI: 0.855–0.931), 0.782 (95% CI: 0.726–0.839), and 0.797 (95% CI: 0.749–0.846), respectively, with corresponding cutpoints of 572.3 HU, 140.4 HU, 25.79, and 6.0. Among these four parameters, SHI was verifiably (DeLong’s test) the most effective predictor of uric acid stones (all p < 0.001). Compared with MSD, VCSD, and urinary pH, SHI may better predict uric acid stones, using a cutpoint of 140.4 HU.

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Low-Dose Unenhanced Computed Tomography with Iterative Reconstruction for Diagnosis of Ureter Stones

Cited by 10 publications

References 20 publications

Preliminary X-ray CT investigation to link Hounsfield unit measurements with the International System of Units (SI)

Preliminary X-ray CT investigation to link Hounsfield unit measurements with the International System of Units (SI)

The Diagnostic Accuracy of Low-Dose Computed Tomography in Diagnosing Urolithiasis: A Systematic Review and Meta-Analysis

Predictors of Uric Acid Stones: Mean Stone Density, Stone Heterogeneity Index, and Variation Coefficient of Stone Density by Single-Energy Non-Contrast Computed Tomography and Urinary pH

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