Summary
Between 1976 and 1994 nephrolithiasis developed in 5.2% of the American inhabitants between ages 20 and 74 years.1 Nephrolithiasis is a recurrent illness with a relapse fee of about 50% in 5 to 10 years.2 Unenhanced CT is a quick, correct methodology of diagnosing urolithiasis in sufferers with acute flank ache.3,4 It’s presently the diagnostic check of alternative for detecting nephrolithiasis. Latest technological advances elevated the quantity of doubtless helpful knowledge that may be obtained from these examinations together with for guiding optimum remedy. DECT gives a instrument to characterize the chemical composition of kidney stones, a key issue for understanding the reason for and potential remedy methods in people. A number of research present that stones might be precisely separated into UA and nonUA sorts utilizing DECT with nearly 100% accuracy.5–8 Qu et al improved the tactic by reporting that extra tin filtration earlier than one of many x-ray tubes additional separated nonUA stones into 4 subgroups.9
The accuracy of stone sort discrimination utilizing DECT is strongly influenced by the efficient atomic variety of stones.10 For stones with a comparatively massive distinction within the efficient atomic quantity, eg UA vs nonUA stones, DECT can separate stone sorts with excessive accuracy, eg 100%.9 Nonetheless, present DECT expertise can not reliably distinguish stones with shut efficient atomic numbers, eg a distinction of lower than 0.5, as a result of lack of a ample signal-to-noise ratio. For instance, COM and COD calculi can’t be discriminated by DECT as a result of they’ve comparable chemical compositions (CaC2O4 · H2O and CaC2O4 · 2H2O) and shut efficient atomic numbers (13.45 and 12.99, respectively).
Nonetheless, discriminating COM and COD stones has potential medical advantages as a result of COD stones reply extra successfully to extracorporeal SWL.11, 12 In vivo differentiation of COM and COD stones could keep away from ineffective, doubtlessly dangerous SWL procedures and enhance preventive medical remedy in sufferers with stones. Moreover, data of stone composition can present data on pathogenic components since COD tends to type at comparatively low supersaturation and excessive calcium-to-oxalate ratios,13 whereas COM is extra attribute of hyperoxaluric states (enteric and first hyperoxaluria.14)
We differentiated COM from COD stones utilizing morphological data gleaned from CT pictures. Kidney stones have distinctive visible morphological options that strongly correlate with chemical composition.14–16 For instance, COM stones normally have easy, mammillary or mulberry-shaped floor morphology, whereas the COD stone floor is normally speculated with bipyramidal crystals with blunt or sharp angles and edges.14 Moreover, stone morphology is distinguishable on radiographic or CT pictures,17–19 which can higher permit stone sort differentiation or prediction of the SWL consequence. Nonetheless, the strategies used to delineate stone morphology in earlier research have been qualitative, much less goal, time-consuming and topic to variability between topics and observers.
To handle these limitations, we developed what’s to our data a novel, totally automated methodology to quantify stone floor morphology from 3D CT pictures. We utilized the tactic to a check knowledge set to find out its skill to distinguish COM and COD stones ex vivo and in vivo.
MATERIALS AND METHODS
Two sorts of picture knowledge have been acquired on this research, together with 1 sort from micro-CT and the opposite from affected person CT pictures. These knowledge units have been processed independently utilizing the identical algorithm.
RESULTS
Determine 2 reveals the floor traits of COM and COD stones on micro-CT. The morphological variations of two stones consultant of the two teams have been quantified by a histogram representing the curvature of the stone floor (fig. 2, a to c). In the entire group of 37 stones the form index was considerably completely different between COM and COD (imply ± SD 0.26 ± 0.23, vary 0.04 to 1.03 vs 0.64 ± 0.15, vary 0.39 to 0.91, p <0.0001, fig. 3, a). Utilizing the form index decided by micro-CT to separate COD from COM stones, the AUC of the ROC curve was 0.92 (95% CI 0.74–0.99, fig. 3, b). The optimum cutoff level used to distinguish stone sorts was decided by the minimal value methodology with equal value weightings for false-negative and false-positive outcomes with 0.93 sensitivity and 0.91 specificity for the differentiation. Determine 4 reveals a consultant affected person picture. General, the form index of COM and COD stones considerably differed on DECT in vivo (imply 0.08 ± 0.02, vary 0.05–0.12 vs 0.12 ± 0.03, vary 0.08 to 0.16, p = 0.008, fig. 5, a). The ROC AUC was 0.90 (95% CI 0.66–1, fig. 5, b). Utilizing the optimum cutoff, sensitivity and specificity have been 1 and 0.73 to distinguish COM and COD, respectively.
DISCUSSION – “calcium oxalate dihydrate stone”
We report what’s to our data the primary try to find out kidney stone composition utilizing morphological options from medical CT pictures. We achieved excessive accuracy for distinguishing COM and COD stone sorts. This methodology requires minimal operator enter and, due to this fact, it’s environment friendly and goal.
SWL is a typical first line, minimally invasive remedy for renal stone illness. The SWL consequence varies relying partly on stone fragility, which in flip is decided by a number of components, together with composition. Cystine and brushite calculi are sometimes most proof against shock waves, adopted in descending order by COM, struvite, COD and UA.27 Utilizing optical microscopy, Daudon et al systematically categorized stone sorts based mostly on morphological and structural look and located a robust relation between stone morphology and kind.14 Thus, since stone morphology may doubtlessly predict the SWL consequence, others studied the connection between stone morphology, formation mechanisms and composition.
Grases investigated stone micromorphology utilizing scanning electron microscopy.15,16 They proposed 2 normal formation mechanisms of hooked up and unattached calculus improvement. Zarse et al used micro-CT to nondestructively characterize kidney stone morphology and chemical composition.28 These research present strong proof of the significance of stone morphological data for analysis.
Others tried to make use of morphological data from medical imaging, eg radiography12,29 and CT,17,19,30 for higher stone administration. Nonetheless, in these research descriptions of stone morphological shapes have been qualitative, which can undergo from interobserver variation. The form index proposed in our research is a quantitative measure of stone morphology straight calculated from 3D CT pictures. Thus, it’s anticipated to be extra constant and handy. This methodology is also helpful for different stone morphological evaluation.
We used micro-CT and medical CT to validate our methodology at 2 spatial decision ranges. Micro-CT is a strong instrument for stone evaluation due to its excessive spatial and distinction decision. In our research the tremendous construction and morphological options of calculi have been clearly seen on micro-CT pictures. Thus, the calculated form index had a a lot bigger dynamic vary than the medical CT pictures. Nonetheless, micro-CT can solely be used for ex vivo research. Moreover, stones despatched for evaluation are sometimes solely items shaped throughout fragmentation of the stone earlier than its removing. Subsequently, the integrity of morphological options might be compromised and the calculated form index could deviate from the calculation utilizing the entire stone. For these causes we confirmed our findings utilizing medical CT pictures.
Though presently medical CT has a lot decrease spatial decision than micro-CT attributable to {hardware} limitation and radiation dose issues, in our research they supplied invaluable in vivo evaluation of intact stones. Certainly, medical CT outcomes have been akin to these of micro-CT, offering a possible alternative to combine quantitative morphological evaluation into an imaging evaluation and remedy algorithm for stone illness. Nonetheless, as a result of morphological distinction in stone samples between the two knowledge units, it was tough to quantitatively examine micro-CT and medical CT outcomes.
There are 2 limitations of this research. For medical scans we selected stones bigger than 5 mm as a result of spatial decision limits of medical CT. Though it will be optimum to check smaller stones, calculi higher than 5 mm are much less more likely to move spontaneously. Subsequently, data of their composition is extra necessary for making surgical administration selections. Sooner or later newer technology scanners could enhance the flexibility to check smaller stones, which can permit composition data to be utilized to this subset for medical analysis and medical administration proposes.
The opposite limitation is that we had a restricted variety of stones in our affected person cohort. Nonetheless, as a result of the distinction was comparatively massive, this preliminary knowledge set was ample to point out the effectiveness of our algorithm. A bigger cohort of affected person shall be included in future research.
CONCLUSIONS
COM and COD stones might be precisely differentiated by micro-CT based mostly on distinctive morphological floor options on micro-CT pictures. These options can be used to distinguish COM from COD stones higher than 5 mm in vivo with cheap accuracy utilizing medical scans. COD and COM calculi might be differentiated utilizing noninvasive, available CT scanners to tell the care of sufferers with stones, together with the selection of surgical intervention.
Acknowledgments