Evaluation of low-dose dual energy computed tomography forin vivoassessment of renal/ureteric calculus composition

Abstract

PurposeThis study aimed to assess the accuracy of low-dose dual-energy computed tomography (DECT) in predicting the composition of urinary calculi.Materials and MethodsA total of 52 patients with urinary calculi were scanned with a 128-slice dual-source DECT scanner by use of a low-dose protocol. Dual-energy (DE) ratio, weighted average Hounsfield unit (HU) of calculi, radiation dose, and image noise levels were recorded. Two radiologists independently rated study quality. Stone composition was assessed after extraction by Fourier transform infrared spectroscopy (FTIRS). Analysis of variance was used to determine if the differences in HU values and DE ratios between the various calculus groups were significant. Threshold cutoff values to classify the calculi into separate groups were identified by receiver operating characteristic curve analysis.ResultsA total of 137 calculi were detected. FTIRS analysis differentiated the calculi into five groups: uric acid (n=17), struvite (n=3), calcium oxalate monohydrate and dihydrate (COM-COD, n=84), calcium oxalate monohydrate (COM, n=28), and carbonate apatite (n=5). The HU value could differentiate only uric acid calculi from calcified calculi (p<0.001). The DE ratio could confidently differentiate uric acid, struvite, calcium oxalate, and carbonate apatite calculi (p<0.001) with cutoff values of 1.12, 1.34, and 1.66, respectively, giving >80% sensitivity and specificity to differentiate them. The DE ratio could not differentiate COM from COM-COD calculi. No study was rated poor in quality by either of the observers. The mean radiation dose was 1.8 mSv.ConclusionsLow-dose DECT accurately predicts urinary calculus composition in vivo while simultaneously reducing radiation exposure without compromising study quality.

Application of Clavien–Dindo Classification System for Complications of Minimally Invasive Percutaneous Nephrolithotomy

“…At the early stage, patients with small diameter stones and mild symptoms can alleviate the illness by drinking lots of water and physical exercises or other conservative treatments [ 4 , 5 ]. However, with the influence of the patient's diets, environmental conditions, and other factors, the diameter of renal stones will be gradually enlarged in some people; consequently, the frequency and duration time of pain will increase, and hematuresis, hydronephrosis, or urinary tract obstruction would be found in some serious patients [ 6 , 7 ]. When conservative treatment does not work for kidney stones, procedures such as transurethral ureteroscopic lithotripsy, percutaneous nephrolithotripsy, and laparoscopic ureterolithotripsy are often considered alternatives to conservative treatment.…”

Role of Dual-Energy Computed Tomography in Urolithiasis

“…DE ratios with cutoff values of 1.12 for uric acid, 1.34 for struvite, and 1.66 for calcium oxalate, and carbonate apatite calculi have >80% sensitivity and specificity to differentiate among these calculi ( p < 0.001). 20 DECT at low energy is thus very useful to get the mineral composition in urolithiasis. The DECT color overlay is also useful in coloring stones of varying composition with different color hues.…”

Dual-Energy Computed Tomography untuk Menentukan Komposisi Batu Urin

“…nilai rasio DECT dapat juga dilakukan melalui diagram alir berdasarkan studi dari Mahalingam dkk. 51 Gambar 3. Diagram alir menggambarkan pendekatan untuk mengidentifikasi komposisi batu berdasarkan nilai rasio DECT.…”

“…Diagram alir menggambarkan pendekatan untuk mengidentifikasi komposisi batu berdasarkan nilai rasio DECT. 51 Penggunaan software post-processing algoritma dekomposisi tiga material ini memungkinkan untuk membedakan asam urat murni, asam urat campuran dan batu non-asam urat. 14,49 Sedangkan untuk membedakan antara jenis batu non-asam urat (batu sistin, hidroksiapatit, kalsium oksalat dan lain-lain) dengan menggunakan pemisahan spektral yang ditingkatkan yang dihasilkan dari penggunaan filter timah pada sumber energi tinggi pada alat DECT.…”