Renal stones, composition

Fig. 36.4a,b. DECT to differentiate urinary renal stone composition. a Axial low-dose, single-energy NCCT image shows an 8-mm stone in the proximal ureter in a 45-year-old male with acute flank pain, b DECT in the same patient and same... 

Eliahou, R., Hidas, G., Duvdevani, M., Sosna, J., 2010. Determination of renal stone composition with dual-energy computed tomography an emerging application. Semin. Ultrasonnd CT 31, 315-320. 

Scholz, D., Schwille, P.O., Ulbrich, D., Bausch, W.M., Sigel, A. Composition of renal stones and their frequency in a stone clinic relationship to parameters of mineral metabolism in serum and urine. Urol. Res. 7 161-170 (1979). 

Approximately 10% of the human population (with regional differences indicating both genetic and environmental factors [33]) is affected by the formation of stones or calculi in the urinary tract. Urolithiasis is not only a painful condition, but also causes annual costs to the health system in the order of billions of dollars in the USA alone [34, 35]. Based on their composition, structure and location in the urinary tract, renal stones have been classified into 11 groups and their formation mechanisms have been discussed together with alterations in urinary parameters and metabolic risk factors for renal lithiasis [35]. Approximately 70% of these stones contain calcium oxalate monohydrate (COM) and dihydrate as major components, while other calculi are composed of ammonium magnesium phosphate (struvite), calcium phosphates (hydroxyapatite and brushite), uric acid and urates, cystine and xanthine. An accurate knowledge of the solubilities of these substances is necessary to understand the cause of renal or bladder calculi formation and find ways towards its prevention and treatment [36]. 

The future of phosphate fibers should be very bright when the patents on the composition expire in 1999. In the author s mind there has never been a safety issue with phosphate fibers or any other inorganic phosphate that does not contain a toxic cationic or anionic function. Phosphates such as sodium, potassium, calcium, magnesium, ammonium, and hydrogen have never caused a problem of any type with perhaps the exception of renal stones. In this case it may be more of a condition than the cause of a condition. Urine is known to be saturated with respect to calcium phosphates. Some threshold agent or other mechanism that is poorly understood keeps kidneys from becoming completely calcified even in the healthiest of persons. 

Strain on the efficacy of a particular technique. The main obstacle for diagnosing them is very subtle visual difference between their sonograms. One possible approach can be texture analysis, because as the composition of the renal stone changes, it produces changes in acoustical properties of the tissue, which could be detected by ultrasound as a textural pattern different for each type. For example, ultra sono graphic images of different concentrations of calcium oxalate monohydrate, dihydrate and carbonate apatite are very similar and it is very difficult, even for an experienced clinician, to perform the diagnosis about the existence and type. Therefore, a reliable non-invasive method for early detection and differentiation of these different is clearly desirable, (see Fig. 1). 

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