Are quantitative features of lung nodules reproducible at different CT acquisition and reconstruction parameters?

Consistency and duplicability in Computed Tomography (CT) output is essential to quantitative imaging for lung cancer detection and monitoring. This study of CT-detected lung nodules investigated the reproducibility of volume-, density-, and texture-based features (outcome variables) over routine ranges of radiation dose, reconstruction kernel, and slice thickness. CT raw data of 23 nodules were reconstructed using 320 acquisition/reconstruction conditions (combinations of 4 doses, 10 kernels, and 8 thicknesses). Scans at 12.5%, 25%, and 50% of protocol dose were simulated; reduced-dose and full-dose data were reconstructed using conventional filtered back-projection and iterative-reconstruction kernels at a range of thicknesses (0.6-5.0 mm). Full-dose/B50f kernel reconstructions underwent expert segmentation for reference Region-Of-Interest (ROI) and nodule volume per thickness; each ROI was applied to 40 corresponding images (combinations of 4 doses and 10 kernels). Typical texture analysis metrics (including 5 histogram features, 13 Gray Level Co-occurrence Matrix, 5 Run Length Matrix, 2 Neighboring Gray-Level Dependence Matrix, and 3 Neighborhood Gray-Tone Difference Matrix) were computed per ROI. Reconstruction conditions resulting in no significant change in volume, density, or texture metrics were identified as "compatible pairs" for a given outcome variable. Our results indicate that as thickness increases, volumetric reproducibility decreases, while reproducibility of histogram- and texture-based features across different acquisition and reconstruction parameters improves. To achieve concomitant reproducibility of volumetric and radiomic results across studies, balanced standardization of the imaging acquisition parameters is required.

Outcome of pulmonary embolism and clinico-radiological predictors of mortality: Experience from a university hospital in Saudi Arabia.

OBJECTIVES: The objective of this study is to determine the outcome of pulmonary embolism (PE) and the clinico-radiological predictors of mortality in a university hospital setting. METHODS: A Prospective observational study conducted at King Khalid University Hospital, Riyadh Saudi Arabia between January 2009 and 2012. A total of 105 consecutive patients (49.9 ± 18.7 years) with PE diagnosed by computed tomography pulmonary angiography were followed until death or hospital discharge. RESULTS: Overall in hospital mortality rate was 8.6%, which is lower than other international reports. Two-thirds of patients developed PE during the hospitalization. The most common risk factors were surgery (35.2%), obesity (34.3%) and immobility (30.5%). The localization of the embolus was central in 32.4%, lobar in 19% and distal in 48.6%. A total of 26 patients (25%) had evidence of right ventricular strain and 14 (13.3%) were hypotensive. Multivariate analysis revealed that heart failure (Beta = -0.53, P < 0.001), palpitation (Beta = -0.24, P = 0.014) and high respiratory rate (Beta = -0.211, P < 0.036) were significant predictors of mortality. There was no significant difference in the localization of the embolus or obstruction score between survivors and non-survivors. CONCLUSION: The outcome of PE is improving; however, it remains an important risk factor for mortality in hospitalized patients. Congestive heart failure, tachypnea and tachycardia at presentation were associated with higher mortality. These factors need to be considered for risk stratification and management decisions of PE patients. Radiological quantification of clot burden was not a predictor of death.

Prediction of pulmonary hypertension in patients with or without interstitial lung disease: reliability of CT findings.

PURPOSE: To study the reliability of pulmonary vascular measurements based on computed tomography (CT) in the prediction of pulmonary hypertension (PH) in patients with advanced interstitial lung disease (ILD) compared with those without ILD. MATERIALS AND METHODS: The study was approved by the Institutional Review Board. All patients gave written informed consent. A prospective study of 134 patients who underwent right-sided heart catheterization and chest CT scanning within 72 hours of admission was conducted. Patients were divided into two groups-one with ILD (group A, n = 100) and one without ILD (group B, n = 34). CT measurements of the main pulmonary artery diameter (PAD), the ratio of PAD to the ascending aorta diameter (AAD), right pulmonary artery diameter (RPAD), and left pulmonary artery diameter (LPAD) were obtained. Univariate logistic regression analysis was performed, and receiver operating characteristic curves were constructed to assess the predictive ability of vascular measurements obtained by using CT in the identification of PH. RESULTS: Main PAD was significantly greater in patients with PH than in those without PH in both groups (group A, P = .008; group B, P = .02). A PAD greater than 25 mm in patients with ILD was predictive of PH, with a sensitivity of 86.4% (32 of 37), a specificity of 41.2% (26 of 63), a positive predictive value of 46.3% (32 of 69), and a negative predictive value of 83.8% (26 of 31). In patients without ILD, a PAD greater than 31.6 mm and an LPAD greater than 21.4 mm were predictive of PH (sensitivity, 47.3% [nine of 19]; specificity, 93.3% [14 of 15]; positive predictive value, 90.0% [nine of 10]; and negative predictive value, 58.3% [14 of 24]). CONCLUSION: CT-derived vascular measurements were of limited utility in the prediction of PH in patients with ILD compared with those without ILD.