No abstract

Purpose To evaluate the image quality of an iterative reconstruction algorithm (IRIS) in low-dose chest CT in comparison with standard-dose filtered back projection (FBP) CT. Materials and methods Eighty consecutive patients referred for a follow-up chest CT examination of the chest, underwent a low-dose CT examination (Group 2) in similar technical conditions to those of the initial examination, (Group 1) except for the milliamperage selection and the replacement of regular FBP reconstruction by iterative reconstructions using three (Group 2a) and five iterations (Group 2b). Results Despite a mean decrease of 35.5% in the doselength-product, there was no statistically significant difference between Group 2a and Group 1 in the objective noise, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios and distribution of the overall image quality scores. Compared to Group 1, objective image noise in Group 2b was significantly reduced with increased SNR and CNR and a trend towards improved image quality. Conclusion Iterative reconstructions using three iterations provide similar image quality compared with the conventionally used FBP reconstruction at 35% less dose, thus enabling dose reduction without loss of diagnostic information. According to our preliminary results, even higher dose reductions than 35% may be feasible by using more than three iterations.

Objective To assess noise reduction achievable with an iterative reconstruction algorithm. Methods 32 consecutive chest CT angiograms were reconstructed with regular filtered back projection (FBP) (Group 1) and an iterative reconstruction technique (IRIS) with 3 (Group 2a) and 5 (Group 2b) iterations.

To determine the histopathologic basis for computed tomographic (CT) interpretation of smokers' lung and the accuracy of CT in the detection of alterations related to cigarette smoking, parenchymal lung lesions were studied from 41 heavy smokers who underwent thoracotomy for removal of a solitary pulmonary nodule. CT scanning of the resected lungs, corresponding exactly to the sections seen on preoperative CT scans, resulted in the following pathologic-CT correlations. Areas of ground-glass attenuation seen on preoperative CT scans (n = 11 [27%]) were related to three main histologic features: (a) accumulation of pigmented macrophages and mucus in the alveolar spaces, associated with mild interstitial inflammation and/or fibrosis (n = 7); (b) thickening of the alveolar walls with inflammatory cells with normal alveolar spaces (n = 3); and (c) presence of organizing alveolitis (n = 1). Parenchymal micronodules depicted presurgically (n = 4 [10%]) corresponded to bronchiolectases with peribronchiolar fibrosis (n = 4) associated with obliterative bronchiolitis in one patient. When emphysema was detected presurgically (n = 21 [51%]), it was always present at pathologic study to a higher extent than initially suspected.

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120414/-/DC1.

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120195/-/DC1.

To evaluate the manifestations of chronic hypersensitivity pneumonitis at radiography and high-resolution computed tomography (HRCT), findings in 16 patients with this disease were reviewed. To ensure objectivity, 50 patients with other chronic infiltrative lung diseases (fibrosing alveolitis [n = 29], sarcoidosis [n = 16], and miscellaneous conditions [n = 5]) were included. All patients had chronic disease with evidence of fibrosis at HRCT, as indicated by irregular linear areas and architectural distortion. Radiographs and HRCT scans were reviewed separately, in random order, and without knowledge of diagnosis. On radiographs and HRCT scans, the fibrosis in cases of hypersensitivity pneumonitis was situated predominantly in the middle lung zones or showed no zonal predominance. Lung apices and bases were relatively spared in all cases. The distribution of fibrosis in the transverse plane was random in seven cases, subpleural in six, and peri-bronchovascular in three. The distribution of fibrosis can allow distinction of chronic hypersensitivity pneumonitis from other causes of fibrosis in many cases.

Systemic sclerosis-related interstitial lung disease (SSc-ILD) is the leading cause of death in SSc. In this study, we aimed to describe the baseline severity and evolution of forced vital capacity (FVC) and diffusing capacity for carbon monoxide (DLCO) in patients with SSc-ILD and to assess the baseline clinical, biological and high-resolution CT scan (HRCT) predictors of this evolution. Baseline and serial FVC and DLCO were collected in 75 SSc-ILD patients followed during 6.4±4.2 years (n = 557 individual data). FVC and DLCO evolution was modelled using a linear mixed model with random effect. During follow-up, FVC was stable while DLCO significantly decreased (-1.5±0.3%/year (p<0.0001). Baseline NYHA functional class III/IV, extensive SSc-ILD on HRCT and DLCO<80% were associated with a lower baseline FVC. Absence of digital ulcers extensive SSc-ILD, and FVC<80% and were associated with a lower baseline DLCO. Presence or history of digital ulcers and presence of pulmonary hypertension at baseline or during follow-up were associated with a faster decline of DLCO overtime. Neither age, gender, subtype of SSc nor specificity of autoantibodies were associated with baseline severity or outcome of lung function tests. In this SSc-ILD population, FVC was therefore stable while DLCO significantly declined over time. ILD extension was associated with baseline FVC and DLCO but not with their evolution. Presence or history of digital ulcers and pulmonary hypertension were predictors of a faster decline of DLCO over time.