Radiation dose levels in pediatric chest CT: experience in 499 children evaluated with dual-source single-energy CT

Paediatric high-pitch lung imaging with photon-counting detector computed tomography: a dose reduction phantom study

BACKGROUND

Photon-counting detector computed tomography (PCD-CT) can reduce radiation dose in paediatric lung imaging.

OBJECTIVE

The aim of this study was to determine the lowest radiation dose maintaining adequate image quality for high-pitch lung imaging using a PCD-CT in a chest phantom replicating the characteristics of a 5-year-old child.

MATERIALS AND METHODS

The phantom was imaged on a dual-source PCD-CT with five different volume CT dose indices (CTDIvol): 0.45 mGy, 0.30 mGy, 0.15 mGy, 0.07 mGy, and 0.01 mGy. Scans were acquired with Sn100 kV in standard and ultra-high resolution modes. Polychromatic images were reconstructed with a 1-mm slice thickness, lung kernel Bl60, without quantum iterative reconstruction and with quantum iterative reconstruction at strengths 2 and 4. Two paediatric radiologists rated reconstructions subjectively, defining adequate image quality as the visibility of small peripheral structures. Objective evaluation included global noise index and global signal-to-noise ratio index.

RESULTS

Exposure times were 0.42 s and 0.84 s for standard and ultra-high resolution modes, respectively. Subjective assessments showed no significant differences across scan modes or quantum iterative reconstruction strengths for both readers at all doses (all, P > 0.05). Scans at 0.07 mGy with quantum iterative reconstruction 4 were deemed to maintain adequate image quality at the lowest dose. Global noise index was always lower and global signal-to-noise ratio index always higher in ultra-high resolution compared with standard mode, underscoring noise reduction achieved via ultra-high resolution mode's small pixel effect.

CONCLUSIONS

PCD-CT enables high-pitch lung imaging while maintaining adequate image quality at a radiation dose as low as 0.07 mGy, with quantum iterative reconstruction 4, in a paediatric phantom representing a 5-year-old child.

Dual-source computed tomography protocols for the pediatric chest - scan optimization techniques

The gold standard for pediatric chest imaging remains the CT scan. An ideal pediatric chest CT has the lowest radiation dose with the least motion degradation possible in a diagnostic scan. Because of the known inherent risks and costs of anesthesia, non-sedate options are preferred. Dual-source CTs are currently the fastest, lowest-dose CT scanners available, utilizing an ultra-high-pitch mode resulting in sub-second CTs. The dual-energy technique, available on dual-source CT scanners, gathers additional information such as pulmonary blood volume and includes relative contrast enhancement and metallic artifact reduction, features that are not available in high-pitch flash mode. In this article we discuss the benefits and tradeoffs of dual-source CT scan modes and tips on image optimization.

Pediatric Congenital Lung Malformations: Imaging Guidelines and Recommendations

Congenital lung malformations are a spectrum of developmental anomalies comprised of malformations of the lung parenchyma, airways, and vasculature. Imaging assessment plays a pivotal role in the initial diagnosis, management, and follow-up evaluation of congenital lung malformations in the pediatric population. However, there is currently a lack of practical imaging guidelines and recommendations for the diagnostic imaging assessment of congenital lung malformations in infants and children. This article reviews the current evidence regarding the imaging evaluation of congenital lung malformations and provides up-to-date imaging recommendations for pediatric congenital lung malformations.

Effectiveness of Chest CT in Children: CT Findings in Relation to the Clinical Question

PURPOSE

 To estimate the effectiveness and efficiency of chest CT in children based on the suspected diagnosis in relation to the number of positive, negative, and inconclusive CT results.

MATERIALS AND METHODS

 In this monocentric retrospective study at a university hospital with a division of pediatric radiology, 2019 chest CT examinations (973 patients; median age: 10.5 years; range: 2 days to 17.9 years) were analyzed with regards to clinical data, including the referring department, primary questions or suspected diagnosis, and CT findings. It was identified if the clinical question was answered, whether the suspected diagnosis was confirmed or ruled out, and if additional findings (clinically significant or minor) were detected.

RESULTS

 The largest clinical subgroup was the hematooncological subgroup (n = 987), with frequent questions for inflammation/pneumonia (66 % in this subgroup). Overall, CT provided conclusive results in 97.6 % of all scans. In 1380 scans (70 %), the suspected diagnosis was confirmed. In 406/2019 cases (20 %), the CT scan was negative also in terms of an additional finding. In 8 of 9 clinical categories, the proportion of positive results was over 50 %. There were predominantly negative results (110/179; 61 %) in pre-stem cell transplant evaluation. In the subgroup of trauma management, 81/144 exams (57 %) showed positive results, including combined injuries (n = 23). 222/396 (56 %) of all additional findings were estimated to be clinically significant.

CONCLUSION

 In a specialized center, the effectiveness of pediatric chest CT was excellent when counting the conclusive results. However, to improve efficiency, the clinical evaluation before imaging appears crucial to prevent unnecessary CT examinations.

KEY POINTS

  · Pediatric chest CT in specialized centers has a high diagnostic value.. · CT identifies relevant changes besides the working hypothesis in clinically complex situations.. · Pre-CT clinical evaluation is crucial, especially in the context of suspected pneumonia..

CITATION FORMAT

· Esser M, Tsiflikas I, Kraus MS et al. Effectiveness of Chest CT in Children: CT Findings in Relation to the Clinical Question. Fortschr Röntgenstr 2021; DOI: 10.1055/a-1586-3023.

Pediatric chest computed tomography at 100 kVp with tin filtration: comparison of image quality with 70-kVp imaging at comparable radiation dose

BACKGROUND

Radiation dose reduction is a primary objective in pediatric populations owing to the well-known risks of radiation-induced cancers. Low-energy photons participate in the radiation dose without significantly contributing to image formation. Their suppression by means of tin filtration should decrease the image noise, anticipating a subsequent application to dose saving.

OBJECTIVE

To investigate the level of noise reduction achievable with tin (Sn) filtration at 100 kVp for chest computed tomography (CT) in comparison with a standard scanning mode at 70 kVp with comparable radiation dose.

MATERIALS AND METHODS

Fifty consecutive children (Group 1) underwent non-contrast chest CT examinations on a third-generation dual-source CT system at tin-filtered 100 kVp and pitch 2. The tube-current time product (mAs) was adjusted to maintain the predicted dose length product (DLP) value at 70 kVp for the respective patient. Each child was then paired by weight and age to a child scanned at 70 kVp on the same CT unit (Group 2); Group 2 patients were consecutive patients, retrospectively selected from our database of children prospectively scanned at 70 kVp. Objective and subjective image quality were compared between the two groups of patients to investigate the overall image quality and level of noise reduction that could be subsequently achievable with tin filtration in clinical practice.

RESULTS

The mean image noise was significantly lower in Group 1 compared to Group 2 when measured in the air (P<0.0001) and inside the aorta (P<0.001). The mean noise reduction was 21.6% (standard deviation [SD] 16.1) around the thorax and 12.0% (SD 32.7) inside the thorax. There was no significant difference in subjective image quality of lung and mediastinal images with excellent overall subjective scores in both groups.

CONCLUSION

At comparable radiation dose, the image noise was found to be reduced by 21.6% compared to the 70-kVp protocol, providing basis for dose reduction without altering image quality in further investigations.

Third-generation dual-source dual-energy CT in pediatric congenital heart disease patients: state-of-the-art

Cardiovascular computer tomography (CT) in pediatric congenital heart disease (CHD) patients is often challenging. This might be due to limited patient cooperation, the high heart rate, the complexity and variety of diseases and the need for radiation dose minimization. The recent developments in CT technology with the introduction of the third-generation dual-source (DS) dual-energy (DE) CT scanners well suited to respond to these challenges. DSCT is characterized by high-pitch, long anatomic coverage and a more flexible electrocardiogram-synchronized scan. DE provides additional clinical information about vascular structures, myocardial and lung perfusion and allows artifacts reduction. These advances have increased clinical indications and modified CT protocol for pediatric CHD patients. In our hospital, DSCT with DE technology has rapidly become an important imaging technique for both pre- and postoperative management of pediatric patients with CHDs. The aim of this article is to describe the state-of-the-art in DSCT protocol with DE technology in pediatric CHD patients, providing some case examples of our experience over an 18-month period.

Neuroblastoma image-defined risk factors in adrenal neuroblastoma: role of radiologist

Neuroblastoma, one of the most common extracranial solid malignancies in children, is often localized in the adrenal glands (49%). The staging system for prognostic purpose was one of the first points of disagreement, which led to the International Neuroblastoma Staging System (INSS) of 1986, revised in 1989, which relies on surgical staging. The limit of this classification was the different surgical resection, also done at interval times from diagnosis. To overcome this difficulty, a new staging system was made based on preoperative imaging by the International Neuroblastoma Risk Group (INRG) in 2009. This new staging system uses 20 Image-Defined Risk Factors (IDRFs) across multiple organ systems. The scope of this IDRFs is to predict surgical outcomes and, in addition with clinical data, to provide risk stratification. The INRG Staging System (INRGSS) relies on Imaging-Defined Risk Factors (IDRFs) that are determined before surgery or other therapy. With the application of the INRGSS the radiologist's role in staging children with neuroblastoma increased. The review provides an overview of the INRGSS and the IDRFs in adrenal neuroblastoma.

Advanced CT Techniques for Decreasing Radiation Dose, Reducing Sedation Requirements, and Optimizing Image Quality in Children

CT is an invaluable diagnostic tool for pediatric patients; however, concerns have arisen about the potential risks of ionizing radiation associated with diagnostic imaging in young patients, particularly for pediatric populations that may require serial CT examinations. Recent attention has also been focused on the immediate and long-term risks of administration of anesthetic medications to infants and young children who require sedation to undergo imaging examinations. These concerns can be mitigated with use of advanced CT techniques that can decrease scan time and radiation dose while preserving image quality. In this article, current state-of-the-art CT acquisition techniques are reviewed as part of a comprehensive strategy to reduce radiation dose, decrease sedation needs, and optimize image quality in infants and young children. Three imaging strategies are discussed, including (a) dual-energy CT (DECT), (b) imaging with a low tube potential, and (c) rapid scanning. Consolidating multiphase imaging protocols into a single phase with virtual nonenhanced imaging on DECT scanners, as well as use of low tube voltage, can reduce the radiation dose while increasing the conspicuity of contrast material-enhanced structures with a reduced volume of iodinated contrast material and a reduced rate of injection. Rapid scanning techniques with either ultrahigh pitch at dual-source CT or with wide-area detector single-source CT facilitate scanning without the need for sedation in many children. ^©RSNA, 2019 See discussion on this article by Szczykutowicz .