Comparison of Radiation Dose and Image Quality of Contrast-Enhanced Dual-Source CT of the Chest: Single-Versus Dual-Energy and Second-Versus Third-Generation Technology.

OBJECTIVE: The purpose of this study was to compare radiation dose and image quality of single- and dual-energy CT (SECT, DECT) examinations of the chest in matched cohorts for second and third-generation dual-source CT (DSCT) systems. MATERIALS AND METHODS: We analyzed 200 patients (100 men; mean age, 61.7 ± 14.8 years old; 100 women, mean age, 59.4 ± 15.1 years old), matched by sex and body mass index, who had undergone clinically indicated contrast-enhanced chest CT. Four study groups, each consisting of 50 patients, were evaluated. Contrast-enhanced chest CT was performed using vendor-preset second-generation DSCT (group A, 120-kV SECT; group C, 80/Sn140-kV DECT) or third-generation DSCT (group B, 90-kV SECT; group D, 90/Sn150-kV DECT) protocols. Radiation dose assessment was normalized to a scan range of 27.5 cm. Image quality was objectively analyzed using dose-independent figure-of-merit (FOM) contrast-to-noise ratio (CNR) calculations and subjectively evaluated by three independent radiologists. RESULTS: Direct comparison of effective radiation dose for second-generation DSCT groups A and C showed statistically significant lower radiation dose values for DECT compared with SECT acquisition (3.2 ± 1.2 mSv vs 2.3 ± 0.6 mSv, p ≤ 0.004), but differences between third-generation SECT and DECT were not significant (1.2 ± 0.9 mSv vs 1.3 ± 0.6 mSv, p = 0.412). FOM CNR analysis revealed highest values for third-generation DECT (p ≤ 0.043). Differences in subjective image quality between the four groups were not statistically significant (p ≥ 0.179). CONCLUSION: Contrast-enhanced DECT examinations of the chest can be performed routinely with second- and third-generation DSCT systems without either increased radiation exposure or decreased image quality compared with SECT acquisition.

A Clinical Feasible Method for Computed Tomography-Based Assessment of Sarcopenia in Patients With Chronic Pancreatitis.

OBJECTIVES: Sarcopenia is a serious but often overlooked complication of chronic pancreatitis (CP). We investigated the prevalence and risk factors for sarcopenia in patients with CP and determined the utility of a computed tomography (CT)-based method, based on psoas muscle measurements, for easy and clinical feasible diagnosis of sarcopenia. METHODS: This was a retrospective multicenter study of 265 patients with CP. We used segmentation of CT images to quantify skeletal muscle mass and diagnose sarcopenia. On the same CT image as used for muscle segmentation, psoas muscle thickness and cross-sectional area were measured and receiver operating characteristic analyses defined age and sex-specific cutoffs for diagnosing sarcopenia. RESULTS: The prevalence of sarcopenia was 20.4%. The optimal height-adjusted psoas muscle cross-sectional area cutoff for diagnosing sarcopenia was 3.3 cm/m in males and 2.5 cm/m in females. The corresponding area under the receiver operating characteristic curves were 0.8 and 0.9, with sensitivities of 84% and 81% and specificities of 62% and 81%, respectively. Comparable diagnostic performance characteristics were observed for psoas muscle thickness. CONCLUSIONS: Sarcopenia is present in 1 of 5 patients with CP. Assessment of psoas muscle parameters provides a clinical feasible method to diagnose sarcopenia.

Reliability and validity of the new VikingSlice software for computed tomography body composition analysis.

BACKGROUND/OBJECTIVES: Body composition assessment by computed tomography (CT) is increasingly used for diagnostic and prognostic purposes in various patient groups. This study aimed to compare the reliability and validity of a newly in-house developed segmentation software VikingSlice against a commercial software (SliceOMatic) for quantification of adipose tissue and skeletal muscle cross-sectional areas (CSA). SUBJECTS/METHODS: Fifty abdominal CT sets from chronic pancreatitis patients were analyzed (mean age 49, range 27-84 years; 38 males). Soft tissue CSAs at level of 4th lumbar vertebra were assessed by measuring standard Hounsfield unit threshold definitions with both softwares. Analysis with VikingSlice included automatic segmentation of interested region with subsequent manual corrections. Analysis with SliceOMatic included manual segmentation of each area. Same investigator measured CSAs using both programs. Inter-observer reliability of CSAs measurements with VikingSlice were assessed by comparing results from two independent investigators. Measurements were compared using the intra-class correlation coefficient (ICC), coefficient of variation (CV), Jaccard index and Bland-Altman analyses. RESULTS: The inter-observer reliability of VikingSlice was excellent (CV 3.4-15.4%, ICC 0.979-0.999, Jaccard index 0.68-0.98). Validity was high (CV 1.6-10.2%, ICC 0.950-0.997) for measurements by SliceOmatic and VikingSlice. The findings were supported in the Bland-Altman plots. The reliability study had small average differences with means of soft tissue compartments in range -2.29 cm2 to 1.56 cm2; average differences between both softwares were -1.28 cm2 to 0.31 cm2. CONCLUSIONS: The in-house developed software VikingSlice was fast and showed good reliability that is comparable with commercial software in its utility to estimate adipose tissue and skeletal muscle CSAs.