Impact of iterative reconstruction on image quality and radiation dose in multidetector CT of large body size adults.
ABSTRACT To compare image quality and radiation dose using Adaptive Statistical Iterative Reconstruction (ASiR) and Filtered Back Projection (FBP) in patients weighing ≥ 91 kg.
In this Institution Review Board-approved retrospective study, single-phase contrast-enhanced abdominopelvic CT examinations of 100 adults weighing ≥ 91 kg (mean body weight: 107.6 ± 17.4 kg range: 91-181.9 kg) with (1) ASiR and (2) FBP were reviewed by two readers in a blinded fashion for subjective measures of image quality (using a subjective standardized numerical scale and objective noise) and for radiation exposure. Imaging parameters and radiation dose results of the two techniques were compared within weight and BMI sub-categories.
All examinations were found to be of adequate quality. Both subjective (mean = 1.4 ± 0.5 vs. 1.6 ± 0.6, P < 0.05) and objective noise (13.0 ± 3.2 vs.19.5 ± 5.7, P < 0.0001) were lower with ASiR. Average radiation dose reduction of 31.5 % was achieved using ASiR (mean CTDIvol. ASiR: 13.5 ± 7.3 mGy; FBP: 19.7 ± 9.0 mGy, P < 0.0001). Other measures of image quality were comparable between the two techniques. Trends for all parameters were similar in patients across weight and BMI sub-categories.
In obese individuals, abdominal CT images reconstructed using ASiR provide diagnostic images with reduced image noise at lower radiation dose.
• CT images in obese adults are noisy, even with high radiation dose. • Newer iterative reconstruction techniques have theoretical advantages in obese patients. • Adaptive statistical iterative reconstruction should reduce image noise and radiation dose. • This has been proven in abdominopelvic CT images of obese patients.
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ABSTRACT: The purpose of our study was to compare a low-dose abdominal CT protocol, delivering a dose of radiation close to the dose delivered by abdominal radiography, with standard-dose unenhanced CT in patients with suspected renal colic. One hundred twenty-five patients (87 men, 38 women; mean age, 45 years) who were admitted with suspected renal colic underwent both abdominal low-dose CT (30 mAs) and standard-dose CT (180 mAs). Low-dose CT and standard-dose CT were independently reviewed, in a delayed fashion, by two radiologists for the characterization of renal and ureteral calculi (location, size) and for indirect signs of renal colic (renal enlargement, pyeloureteral dilatation, periureteral or renal stranding). Results reported for low-dose CT, with regard to the patients' body mass indexes (BMIs), were compared with those obtained with standard-dose CT (reference standard). The presence of non-urinary tract-related disorders was also assessed. Informed consent was obtained from all patients. In patients with a BMI < 30, low-dose CT achieved 96% sensitivity and 100% specificity for the detection of indirect signs of renal colic and a sensitivity of 95% and a specificity of 97% for detecting ureteral calculi. In patients with a BMI < 30, low-dose CT was 86% sensitive for detecting ureteral calculi < 3 mm and 100% sensitive for detecting calculi > 3 mm. Low-dose CT was 100% sensitive and specific for depicting non-urinary tract-related disorders (n = 6). Low-dose CT achieves sensitivities and specificities close to those of standard-dose CT in assessing the diagnosis of renal colic, depicting ureteral calculi > 3 mm in patients with a BMI < 30, and correctly identifying alternative diagnoses.American Journal of Roentgenology 05/2007; 188(4):927-33. · 2.90 Impact Factor
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ABSTRACT: This paper presents a general statistical methodology for the analysis of multivariate categorical data arising from observer reliability studies. The procedure essentially involves the construction of functions of the observed proportions which are directed at the extent to which the observers agree among themselves and the construction of test statistics for hypotheses involving these functions. Tests for interobserver bias are presented in terms of first-order marginal homogeneity and measures of interobserver agreement are developed as generalized kappa-type statistics. These procedures are illustrated with a clinical diagnosis example from the epidemiological literature.Biometrics 04/1977; 33(1):159-74. · 1.41 Impact Factor
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ABSTRACT: The increasing prevalence and associated sociodemographic disparities of morbid obesity are serious public health concerns. Bariatric surgical procedures provide greater and more durable weight reduction than behavioral and pharmacological interventions for morbid obesity. To examine trends for elective bariatric surgical procedures, patient characteristics, and in-hospital complications from 1998 to 2003 in the United States. The Nationwide Inpatient Sample was used to identify bariatric surgery admissions from 1998-2002 (with preliminary data for 12 states from 2003) using International Classification of Diseases, Ninth Revision, codes for foregut surgery with a confirmatory diagnosis of obesity or by diagnosis related group code for obesity surgery. Annual estimates and trends were determined for procedures, patient characteristics, and adjusted complication rates. Trends in bariatric surgical procedures, patient characteristics, and complications. The estimated number of bariatric surgical procedures increased from 13,365 in 1998 to 72,177 in 2002 (P<.001). Based on preliminary state-level data (1998-2003), the number of bariatric surgical procedures is projected to be 102 794 in 2003. Gastric bypass procedures accounted for more than 80% of all bariatric surgical procedures. From 1998 to 2002, there were upward trends in the proportion of females (81% to 84%; P = .003), privately insured patients (75% to 83%; P = .001), patients from ZIP code areas with highest annual household income (32% to 60%, P<.001), and patients aged 50 to 64 years (15% to 24%; P<.001). Length of stay decreased from 4.5 days in 1998 to 3.3 days in 2002 (P<.001). The adjusted in-hospital mortality rate ranged from 0.1% to 0.2%. The rates of unexpected reoperations for surgical complications ranged from 6% to 9% and pulmonary complications ranged from 4% to 7%. Rates of other in-hospital complications were low. These findings suggest that use of bariatric surgical procedures increased substantially from 1998 to 2003, while rates of in-hospital complications were stable and length of stay decreased. However, disparities in the use of these procedures, with disproportionate and increasing use among women, those with private insurance, and those in wealthier ZIP code areas should be explored further.JAMA The Journal of the American Medical Association 10/2005; 294(15):1909-17. · 29.98 Impact Factor