Comparison Between Computed Tomography and Ultrasonography in Detection of Urinary Tract Calculi

Introduction: In the past decade, developments in CT technology have changed the trend of imaging modalities used in the evaluation of urinary system. The present study was undertaken to compare between Computed Tomography (CT) and Ultrasonography (USG) in detection of urinary tract calculi.  Methods: The prospective, cross-sectional and observational research design was used. The study was conducted in Department of Radiology and Imaging of Tribhuvan University Teaching Hospital from June 2017 to September 2017 in 96 patients. Patients who underwent plain CT abdomen (CT KUB) with suspicion of urolithiasis after performing USG were enrolled in the study. Ultrasound and CT findings were compared on the basis of age, gender, clinical complaints, number of stones and their locaton (site of occurrence). Similarly, specificity, sensitivity, positive predictive value and negative predictive value of USG were calculated using CT as gold standard.  Results: A total number of 96 patients were studied from June 2017 to September 2017. Among them 56 were males and 40 were females with male to female ratio of 1.4:1. The mean age among the males was 34±14.79 years and  females was 38±18.74 years. Flank pain was the commonest complaint recorded in 35.41% of patients. On the CT scan, 80% patients had renal calculi, 15.60% of stones were found in vesico-ureteric junction (VUJ) and 41.66% stones were seen bilaterally. Out of the 22 cases with ureteric calculi, USG detected calculi only in 5 cases and the sensitivity of USG in diagnosing ureteric calculi in comparision to CT was 22.72% with 100 % specificity, 100% PPV and 81% NPV.  Conclusion: Ultrasound has lower sensitivity for the detection of ureteric calculi. CT helps in precise detection of calculi during initial evaluation which is critical for clinical decision making and patient counselling.

Comparative Study of Image Quality and Radiation Dose between 120kVp Filtered Back Projection and 80kVp Iterative Reconstructed Computed Tomography Images

Background: Iterative Reconstruction techniques have been shown to produce diagnostically acceptable images at low doses to the patient. This study aimed to compare the image quality and radiation dose between 120kVp Filtered Back Projection and 80kVp Iterative Reconstructed (SAFIRE) CT images. Methods: This cross-sectional study was performed on patients referred for CT Urography examinations for various clinical indications to the Department of Radiology and Imaging, Tribhuvan University Teaching Hospital. Data were collected for a period of four months (From August to November 2019) after approval from the Institutional Review Committee of the Institute of Medicine. Convenience sampling was employed and a total of 96 examinations were included. Among them 48 were male and 48 were female. Data were obtained from the 128-slice MDCT Siemens Somaton Definition AS+ CT scanner. Venous phase scans were obtained with Protocol A (120kVp and Filtered Back Projection) and non-contrast scans were obtained with Protocol B (80kVp and SAFIRE). The mAs (tube current-time product) was fixed at 200 for both protocols. Results: There was a 72.5% reduction in Size Specific Dose Estimate (SSDE) in Protocol B compared to Protocol A. However, there was a 13.17% increase in noise in Protocol B compared to Protocol A. Image quality evaluation showed a 98.95% acceptability for the low dose i.e. Protocol B images. Conclusion: CT using low kVp (80kVp) and low current (200mAs) along with an iterative reconstruction algorithm (SAFIRE) can provide diagnostically acceptable images at very low doses for examinations of the Urinary trac

Dose optimization in computed tomography of brain using CARE kV and CARE Dose 4D

Background: Computed Tomography (CT) scan of brain is the most widely used CT examination. Latest CT scanners have the potential to deliver very low radiation dose by utilizing tube potential and tube current modulation techniques. We aim to determine the application of CARE kV (tube potential modulation) and CARE Dose4D (tube current modulation) in CT scan of brain. Both CARE kV and CARE Dose4D are well-established innovative technology of Siemens Medical Solutions. Methodology: A prospective hospital-based study was conducted during four months at Tribhuvan University Teaching Hospital (TUTH). The data were collected on a Siemens Somatom Definition Edge 128 slices CT scanner. Non-random purposive sampling technique was employed. Ethical approval and consent to participate were taken for every participant. Non-contrast (NC) CT images were acquired without using CARE kV and CARE Dose4D, whereas during contrast-enhanced (CE) investigation, both were turned on keeping other scanning parameters constant for each individual. Results: A total of 72 patients, 42 males and 28 females - mean age 41y (range 16-87y) participated in this study. The Body Mass Index (BMI) was 22.0, range 20.1-25.0. The mean value of Computed Tomography Dose Index (CTDI), Dose Length Product (DLP) and Effective Dose (ED) before and after switching on both CARE kV and CARE Dose4D were 58.19±0.35 and 39.67±3.59 milli-Gray (mGy), 946.67 and 652.58 mGy-cm, and 1.98 and 1.36 milli-Sievert (mSv) respectively. Conclusion: CARE kV and CARE Dose4D can reduce radiation dose in CT scan of brain without loss of image quality