Radiology Imaging of Bronchiectasis in Children and Adolescents (Literature Review with Own Observations)

Timely detection of bronchiectasis in children is of great prognostic value. The importance of modern bronchiectasis in children is due to their possible reversibility over time with effective treatment, as well as a number of significant differences between bronchiectasis in childhood and onset in children, which may reflect different phenotypes of bronchiectasis. In adult patients with bronchiectasis that began in childhood, the pathological process has a more severe and worse prognosis compared to bronchiectasis that began in adulthood. In 2020, the European Respiratory Society proposed a new formulation of the terminal «bronchiectasis» for children and adolescents, now this term refers to an abnormal expansion of the bronchi by computed tomography (CT) of the chest, which, if detected early, can be reversible. CT is the true «gold standard» for confirming bronchiectasis in children and adolescents. This method is included in the minimum set of tests for children and adolescents with suspected bronchiectasis according to the recommendations of the European Respiratory Society. When conducting CT, it is recommended to perform a continuous spiral scan with a collimation of 1 mm, the study is carried out without intravenous use using low-dose protocols. To assess the state of the bronchi in children and adolescents, it is necessary to use the pediatric norms of the broncho-arterial ratio (> 0.8). At the same time, radiation methods are not decisive in establishing the causes of bronchiectasis and only in rare cases can help in establishing bronchiectasis. Dynamic observation of bronchiectasis for children and adolescents is determined individually. Consideration should be given to repeat chest computed tomography scans to answer the question that will change treatment.

PSEUDOGRADIENT ALGORITHM FOR IDENTIFICATION OF DOUBLY STOCHASTIC CYLINDRICAL IMAGE

Nowadays image processing problems are becoming increasingly important due to development of the aerospace Earth monitoring systems, radio and sonar systems, medical devices for early diagnosis, etc. However, the most of the image processing works deals with images defined on rectangular two-dimensional grids or grids of higher dimension. In some practical situations images are set on a cylinder, for example images of pipeline sections, blood vessels, rotary parts, etc. The peculiarity of the domain for specifying such images requires its consideration in their models and processing algorithms. The article deals with autoregressive models of cylindrical images and gives some expressions of the correlation function depending on the autoregression parameters are given. To represent heterogeneous images with random heterogeneities, ‘doubly stochastic’ models are used in which one or more images control the parameters of resulted image. The spiral scan of a cylindrical image can be considered as a quasiperiodic process due to the correlation of image rows. The article proposes the pseudogradient algorithms for the modal identification. The statistical modeling proves these algorithms give good model identification.

Radiation Dose Reduction in Preprocedural CT Imaging for TAVI/TAVR Using a Novel 3-Phase Protocol: A Single Institution’s Experience

Purpose To retrospectively investigate the effectiveness of a novel 3-phase protocol for computed tomography (CT) before transcatheter aortic valve implantation/transcatheter aortic valve replacement (TAVI/TAVR) in terms of radiation dose and image quality. Materials and Methods A total of 107 nonrandomized patients (81 ± 7.4 years) scheduled for TAVI/TAVR underwent preprocedural CT on an 80-row CT scanner. 55 patients underwent a combined ECG-synchronized spiral scan of the chest and non-ECG-synchronized spiral scan of the abdomen/pelvis as recommended by the Society of Cardiovascular Computed Tomography (SCCT). 52 patients underwent an updated 3-phase variable helical pitch (vHP3) protocol combining a non-ECG-synchronized spiral scan of the upper thoracic aperture, followed by a prospective ECG-synchronized spiral scan of the heart, and a non-ECG-synchronized abdominal/pelvic spiral scan. The radiation dose was determined from an automatically generated protocol based on the CT dose index (CTDI). Objective image quality in terms of vessel attenuation and image noise was measured, and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective image quality was evaluated using a 4-point scale and compared for interrater agreement using Cohen’s weighted kappa coefficient (κw). All data were compared and statistically analyzed. Results Use of the novel 3-phase vHP3 protocol reduced the dose-length product (DLP) from 1256.58 ± 619.05 mGy*cm to 790.90 ± 238.15 mGy*cm, reducing the effective dose (E) from 21.36 ± 10.52 mSv to 13.44 ± 4.05 mSv and size-specific dose estimates (SSDE) from 20.85 ± 7.29 mGy to 13.84 ± 2.94 mGy (p < 0.001). There were no significant differences in objective and subjective image quality between the two protocols and between the two readers. Conclusion The novel 3-phase vHP3 protocol significantly reduces the radiation dose of preprocedural TAVI/TAVR CT without a loss of image quality. Key Points: Citation Format