ABSTRACT
PURPOSE: This study aimed to assess the accuracy of low-dose dual-energy computed tomography (DECT) in predicting the composition of urinary calculi. MATERIALS AND METHODS: A 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. RESULTS: A 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 (p80% 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. CONCLUSIONS: Low-dose DECT accurately predicts urinary calculus composition in vivo while simultaneously reducing radiation exposure without compromising study quality.
Subject(s)
Adult , Female , Humans , Male , Middle Aged , Young Adult , Apatites/analysis , Calcium Oxalate/analysis , Image Interpretation, Computer-Assisted/methods , Kidney Calculi/chemistry , Magnesium Compounds/analysis , Phosphates/analysis , Prospective Studies , Radiation Dosage , Tomography, X-Ray Computed/methods , Ureteral Calculi/chemistry , Uric Acid/analysis , Waist CircumferenceABSTRACT
To determine the utility of tissue harmonic imaging in evaluating cystic renal lesions and to compare these findings with conventional ultrasound guidance [USG] and CT. Thirty patients, detected with cystic renal lesions on routine USG [over a period of 18 months from July 2004 to December 2005 at the Postgraduate Institute of Medical Education and Research Chandigarh, Chandigarh, India] were included in this study. All patients underwent a conventional gray scale ultrasound study [GSI], followed by tissue harmonic imaging [THI] sonography on the same machine [advance technology limited high definition imaging 5000]. Computed tomography of abdomen was carried out within one week of the ultrasound examinations. All images were evaluated for size, number, and location of lesions. The findings of THI sonography, conventional USG and CT of abdomen were recorded in their respective proformas. The images obtained by GSI, THI, and contrast enhanced CT were also evaluated for image quality, lesion conspicuity, and fluid-solid differentiation. Tissue harmonic imaging showed better image quality in 27 of 34 lesions, improvement in lesion conspicuity was found in 27 of 34 cystic lesions, and an improved solid-fluid differentiation in 30 of 34 lesions when compared to GSI. The THI provided additional information as compared to GSI in 8 patients. The grading of CT scan was significantly higher in overall image quality [p=0.007] and lesion conspicuity [p=0.004], but was non-significant for fluid-solid differentiation [p=0.23]. Tissue harmonic imaging provides better image quality, lesion delineation, and superior characterization than conventional gray scale sonography