title: Prediction of calcium level in melamine-related urinary calculi with helical CT: diagnostic performance evaluation and clinical significance.
abstract: The aim of the study was to investigate the relationship between CT-attenuation and stone calcium level in melamine-related urinary calculi (MRUC). A total of 25 MRUC with known composition and calcium level were included (11 uric acid stones, 2 calcium oxalate stones and 12 mixture stones of uric acid and calcium oxalate). Of all, 18 renal stones accepted alkalization therapy except for 5 lower urinary tract stones and 2 stones of unknown position. With well-matched composition, 61 adult urinary stones were included as controls. Every stone was scanned by helical CT (80 kV/120 kV, 300 mA, pitch 0.625 mm) and the highest CT-attenuation value measured. CT-attenuation values of MRUC increased gradually from uric acid stones, mixture stones to calcium oxalate stones, but were always lower than the values of controls. Furthermore, a strong positive correlation was found between stone CT-attenuation value and stone calcium level (n = 25, r (80kV) = 0.883, p = 0.000; r (120kV) = 0.855, p = 0.000). Compared with alkalization-therapy-alone group, stone CT-attenuation values and stone calcium level in the comprehensive-therapy group were significantly greater (CT(80kV) 1,057 ± 639 vs. 172 ± 61 HU, p = 0.001; CT(120kV) 783 ± 476 vs. 162 ± 60 HU, p = 0.001; Ca 19.83 ± 7.48% vs. 1.30 ± 1.51%, p = 0.000). Fisher's exact test suggested that the stones with higher CT-attenuation values tended to resist alkalization when 400 HU served as the cutoff value (P (80kV) = 0.002, P (120kV) = 0.000). In conclusion, the study was the first to illustrate that the CT-attenuation value could reflect calcium level in MRUC and found that stones with higher CT-attenuation value were not amenable to alkalization because they probably contained greater calcium. For those patients, we believe that comprehensive therapy will be the best choice.
authors.affiliation: Center Lab, The People's Hospital in Gansu Province, Lanzhou, Gansu, China. ly4139@163.com
authors.forename: Li
authors.initials: L
authors.lastname: Yuan
authors.forename: Ru
authors.initials: R
authors.lastname: Xiaorui
authors.forename: Huang
authors.initials: H
authors.lastname: Gang
authors.forename: Xi
authors.initials: X
authors.lastname: Xinsheng
authors.forename: Huang
authors.initials: H
authors.lastname: Xiaogang
authors.forename: Dong
authors.initials: D
authors.lastname: Li
authors.forename: Chen
authors.initials: C
authors.lastname: Yirong
mesh_terms: D002118:Calcium / Q000032:analysis*; D006801:Humans; D012189:Retrospective Studies; D036542:Tomography, Spiral Computed / Q000379:methods*; D014227:Triazines / Q000633:toxicity*; D014545:Urinary Calculi / Q000737:chemistry* / Q000000981:diagnostic imaging / Q000628:therapy
chemical_list: D014227:Triazines; C011907:melamine; D002118:Calcium