Chest CT in infants and children

Radiation-free and injection-free imaging of the paediatric chest using a magnetic resonance imaging protocol including zero time echo sequence (3D-ZTE)

Computed tomography (CT) is commonly used for paediatric thoracic diseases but involves radiation exposure and often requires intravenous contrast. We evaluated the performance of a magnetic resonance imaging (MRI) protocol including a 3D zero echo time (3D-ZTE) sequence for radiation-free and contrast-free imaging of the paediatric chest. In this prospective, single-centre study, children aged 6-16 years underwent chest CT and MRI within 48 h. CT and MRI exams were independently assessed by two paediatric radiologists. The primary outcome was the image quality of the 3D-ZTE sequence using a scoring system based on the acceptability of the images obtained and visibility of bronchial structures, vessels and fissures. Secondary outcomes included radiologists' ability to detect lung lesions on 3D-ZTE MRI images compared with CT images. Seventy-two children were included. Overall, the image quality achieved with the 3D-ZTE MRI sequence was inferior to that of CT for visualising pulmonary structures, with satisfactory lung image quality observed for 81.9% (59/72) and 100% (72/72) of patients, respectively. However, MRI sensitivity was excellent (above 90%) for the detection of certain lesions such as lung consolidation, proximal mucoid impactions, pulmonary cysts, ground glass opacities and honeycombing. Intermodality agreement (MRI versus CT) was consistently higher for the senior reader compared to the junior reader.

CONCLUSION

Despite its overall lower image quality compared to CT, and the additional years of experience required for accurate interpretation, the 3D-ZTE MRI sequence demonstrated excellent sensitivity for several lesions, making it an appropriate imaging method in certain indications.

WHAT IS KNOWN

• Chest radiography and CT are the main imaging modalities for paediatric thoracic diseases but involve radiation exposure and CT often requires IV contrast. • MRI is promising for radiation-free lung imaging in children but faces challenges of low signal-to-noise ratio and motion artefacts.

WHAT IS NEW

• An MRI protocol including a 3D zero echo time (ZTE) sequence allows satisfactory visualisation of lung parenchyma in 82% of children. • Despite overall inferior image quality compared to CT, MRI demonstrated excellent sensitivity for several lesions, making it an appropriate imaging method in certain indications.

Neonatal and Infant Lung Disorders: Glossary, Practical Approach, and Diagnoses

A multitude of lung disorders ranging from congenital and genetic anomalies to iatrogenic complications can affect the neonate or the infant within the first year of life. Neonatal and infant chest imaging, predominantly by plain radiography and computed tomography, is frequently employed to aid in diagnosis and management; however, these disorders can be challenging to differentiate due to their broad-ranging, and frequently overlapping radiographic features. A systematic and practical approach to imaging interpretation which includes recognition of radiologic patterns, utilization of commonly accepted nomenclature and classification, as well as interpretation of imaging findings in conjunction with clinical history can not only assist radiologists to suggest the diagnosis, but also aid clinicians in management planning. The contents of this article were endorsed by the leadership of both the World Federation of Pediatric Imaging (WFPI), and the International Society of Pediatric Thoracic Imaging (ISPTI).

Strategies for recognizing pneumonia look-alikes

Community-acquired pneumonia is a common diagnosis in children. Among the many children whose symptoms and/or chest X-ray is consistent with community-acquired pneumonia, it can be difficult to distinguish the rare cases of differential diagnoses that require specific management. The aim of this educational article is to provide clinicians with a series of questions to ask themselves in order to detect a possible differential diagnosis of pneumonia in children. The value of this approach is illustrated by 13 real clinical cases in which a child was misdiagnosed as having lobar pneumonia. What is Known: • When a lobar pneumonia is diagnosed, an appropriate antibiotic treatment leads to the resolution of the clinical signs in most cases. • However, several diseases can be look-alikes for pneumonia and mislead the practitioner. What is New: • This article provides a new approach to identify differential diagnoses of pneumonia in children. • It is illustrated by 13 real-life situations of children misdiagnosed as having pneumonia.

Magnetic Resonance Imaging Assessment of Pulmonary Vascularity in Infants with Congenital Diaphragmatic Hernia: A Novel Tool for Direct Assessment of Severity of Pulmonary Hypertension and Hypoplasia

OBJECTIVES

To assess the feasibility of magnetic resonance imaging (MRI) for postnatal assessment of pulmonary vascularity in infants with congenital diaphragmatic hernia (CDH).

STUDY DESIGN

Infants with prenatally diagnosed CDH (n = 24) received postnatal pulmonary MRI. Infants with nonpulmonary birth defects served as controls (n = 5). Semiautomatic segmentation was performed to obtain total vascular volume using time of flight images to assess vascularity.

RESULTS

Average vascular density (vascular volume/lung volume) in control infants was 0.23 ± 0.06 mm³/mm³ compared with 0.18 ± 0.06 mm³/mm³ in infants with CDH is (P = .09). When stratified further based on CDH severity, the difference between control infants and moderate CDH group was statistically significant. (0.23 mm³/mm³ vs 0.15 mm³/mm³, P = .01). Ipsilateral vascular density on MRI in infants with CDH significantly correlated with the prenatal pulmonary hypertensive index (P = .0004, Spearman R = +0.87) and with number of days on mechanical ventilation (P = .04, Spearman R = -0.44), total days on inhaled nitric oxide (P = .02, Spearman R = -0.47), use of epoprostenol for acute pulmonary hypertension (PH) (0.14 mm³/mm³ vs 0.20 mm³/mm³, P = .005), and use of sildenafil for chronic PH (0.15 mm³/mm³ vs 0.19 mm³/mm³, P = .03).

CONCLUSIONS

Our results suggest that postnatal pulmonary vascularity assessed by MRI strongly correlates with prenatal and postnatal markers of PH severity and that pulmonary vascularity may serve as a direct measure of pulmonary vascular hypoplasia in infants with CDH.

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.

CTA utilization for evaluation of suspected pulmonary embolism in a tertiary pediatric emergency department

OBJECTIVE

To evaluate changes in the utilization of computed tomography angiography (CTA) for evaluating suspected pulmonary embolism (PE) and the positive rate of ancillary for those studies negative for PE in the last 13 years.

MATERIALS AND METHODS

A retrospective review of patient ≤ 20 years of age who underwent a chest CT angiography to rule out PE was performed in a 13-year-period. CT angiographies were grouped into three categories: Positive for PE, negative for PE and positive for ancillary findings, and negative for any pathology. From the exams with ancillary findings, we examined how many of these had a chest radiograph perform within 24 h prior to the CTA and how many of them had an impression stating the same conclusion as the CTA.

RESULTS

307 chest CT angiographies for suspected PE were included. 50 (16%) were reported as positive for PE and 91 (30%) were negative for PE but positive for ancillary findings. The most frequent ancillary findings were pneumonia (n = 26) and pleural effusion (n = 11). Out of 91, 73 patients had a previous chest radiograph and 28 of them reported a similar diagnosis than the CTA. The number of CT angiographies indicated for PE increased by 3.2 studies per year. The rate of CT angiographies positive for ancillary findings (slope = 1.5) and positive for PE (slope = 0.3) remained similar throughout the same period.

CONCLUSIONS

CTA orders for PE have been increasing without any increased detection of PE or ancillary findings in children.

Neonatal Lung Disorders: Pattern Recognition Approach to Diagnosis

OBJECTIVE

Lung disease is a common indication for neonates to require medical attention, and neonatal chest radiographs are among the most common studies interpreted by pediatric radiologists. Radiographic features of many neonatal lung disorders overlap, and it may be difficult to differentiate among conditions.

CONCLUSION

This review presents an up-to-date practical approach to the radiologic diagnosis of neonatal lung disorders, with a focus on pattern recognition and consideration of clinical history, patient age, and symptoms.

Imaging the Infant Chest without Sedation: Feasibility of Using Single Axial Rotation with 16-cm Wide-Detector CT

Purpose To compare image quality, patient preparation time, and radiation dose using a single axial rotation with 16-cm wide-detector computed tomography (CT) in imaging the infant chest without sedation with those in infants examined by using a 64-row CT and sedation. Materials and Methods Thirty-two infants (group 1) were prospectively enrolled to undergo nonenhanced chest CT without sedation using a single axial rotation on a 16-cm wide-detector CT scanner. Patients were imaged with automatic tube current modulation and tube voltages of 80 kVp for patients weighing 5 kg or less and 100 kVp for patients weighing more than 5 kg. Patient preparation time, CT dose index (CTDI), dose-length product (DLP), and image quality were compared with those in a historical control group consisting of 30 infants (group 2) who underwent conventional helical scanning with sedation performed by using a 64-row volume CT scanner. The Student t test for independent samples was used to assess continuous variables. The Mann-Whitney rank test and the κ test were used to evaluate image quality. Results There was no statistically significant difference in body weight, age, mean CT attenuation value, image noise, and subjective image quality score between the two groups. However, compared with the group scanned by using a 64-row volume CT scanner (group 2), group 1 experienced significantly reduced scan time by 83% (0.35 second vs 2.01 seconds ± 0.21 [standard deviation]), preparation time by 57% (41.25 minutes ± 103.78 vs 96.5 minutes ± 151.77), CTDI by 42% (2.03 mGy ± 0.4 vs 3.52 mGy ± 0.03), and DLP by 52% (27.07 mGy·cm ± 6.97 vs 55.84 mGy·cm ± 6.46) (P < .05 for all). Conclusion Compared with conventional 64-row helical CT with sedation, use of a single axial rotation with 16-cm wide-detector CT in imaging the infant chest without sedation can reduce radiation dose, preparation time, and total scan time, while providing comparable image quality. ^© RSNA, 2017.

Computed tomography dose optimisation in cystic fibrosis: A review

Cystic fibrosis (CF) is the most common autosomal recessive disease of the Caucasian population worldwide, with respiratory disease remaining the most relevant source of morbidity and mortality. Computed tomography (CT) is frequently used for monitoring disease complications and progression. Over the last fifteen years there has been a six-fold increase in the use of CT, which has lead to a growing concern in relation to cumulative radiation exposure. The challenge to the medical profession is to identify dose reduction strategies that meet acceptable image quality, but fulfil the requirements of a diagnostic quality CT. Dose-optimisation, particularly in CT, is essential as it reduces the chances of patients receiving cumulative radiation doses in excess of 100 mSv, a dose deemed significant by the United Nations Scientific Committee on the Effects of Atomic Radiation. This review article explores the current trends in imaging in CF with particular emphasis on new developments in dose optimisation.

Pediatric Chest CT: Wide-Volume and Helical Scan Modes in 320-MDCT

OBJECTIVE

The purpose of this study was to compare wide-volume and helical pediatric 320-MDCT of the chest with respect to radiation dose and image quality.

MATERIALS AND METHODS

From November 2012 to September 2013, 59 wide-volume and 47 helical pediatric chest 320-MDCT images were obtained. The same tube potential and effective tube current-time product were applied in the two groups according to patient weight (group A, < 10 kg, n = 18; group B, 10-19.9 kg, n = 60; group C, 20-39.9 kg, n = 28). To compensate for overranging, adjusted CT dose index (CTDI) was calculated by dividing dose-length product (DLP) by the scan ranges imaged. Adjusted CTDI, DLP, overall image quality, motion artifact, noise, and scan ranges were compared by Mann-Whitney U test or t test.

RESULTS

The adjusted CTDI was significantly lower in the group who underwent wide-volume CT than in the group who underwent helical CT (weight group A, p < 0.001; group B, p < 0.001; group C, p = 0.003). The DLP was lower in the wide-volume group than in the helical CT group in weight groups A (p < 0.001) and B (p < 0.001) but not in group C (p = 0.162). All CT scans were of diagnostic quality, and there was no significant difference between the wide-volume and helical CT groups (p = 0.318). The motion artifact score was significantly higher in the wide-volume group than in the helical CT group in groups B (p < 0.001) and C (p = 0.010) but not in group A (p = 0.931). The noise was significantly lower in the wide-volume group than in the helical CT group (p < 0.001).

CONCLUSION

In pediatric chest CT, use of wide-volume CT can decrease radiation exposure while preserving image quality. It is associated with less noise than helical CT but may be subject to more motion artifact.

Pediatric Computed Tomography Dose Optimization Strategies: A Literature Review

INTRODUCTION

Computed tomography (CT) dose optimization is an important issue in radiography because CT is the largest contributor to medical radiation dose and its use is increasing. However, CT dose optimization for pediatric patients could be more challenging than their adult counterparts. The purpose of this literature review was to identify and discuss the current pediatric CT dose saving techniques. Optimized pediatric protocols were also proposed.

METHODS

A comprehensive literature search was conducted using the Medline, ProQuest Health and Medical Complete, PubMed, ScienceDirect, Scopus, Springer Link, and Web of Science databases and the keywords CT, pediatric, optimization, protocol, and radiation dose to identify articles focusing on pediatric CT dose optimization strategies published between 2004 and 2014.

RESULTS AND SUMMARY

Seventy-seven articles were identified in the literature search. Strategies for optimizing a range of scan parameters and technical considerations including tube voltage and current, iterative reconstruction, diagnostic reference levels, bowtie filters, scout view, pitch, scan collimation and time, overscanning, and overbeaming for pediatric patients with different ages and body sizes and compositions were discussed. An example of optimized pediatric protocols specific to age and body size for the 64-slice CT scanners was devised. It is expected that this example could provide medical radiation technologists, radiologists, and medical physicists with ideas to optimize their pediatric protocols.

Evaluation of the impact of organ-specific dose reduction on image quality in pediatric chest computed tomography

BACKGROUND

Organ-specific dose reduction significantly reduces the radiation exposure of radiosensitive organs.

OBJECTIVE

The purpose of this study was to assess the impact of a novel organ-specific dose reduction algorithm on image quality of pediatric chest CT.

MATERIALS AND METHODS

We included 28 children (mean age 10.9 ± 4.8 years, range 3-18 years) who had contrast-enhanced chest CT on a 128-row scanner. CT was performed at 100 kV using automated tube current modulation and a novel organ-specific dose-reduction algorithm (XCare™; Siemens, Forchheim, Germany). Seven children had a previous chest CT performed on a 64-row scanner at 100 kV without organ-specific dose reduction. Subjective image quality was assessed using a five-point scale (1-not diagnostic; 5-excellent). Contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were assessed in the descending aorta.

RESULTS

Overall mean subjective image quality was 4.1 ± 0.6. In the subgroup of the seven children examined both with and without organ-specific dose reduction, subjective image quality was comparable (score 4.4 ± 0.5 with organ-specific dose reduction vs. 4.4 ± 0.7 without it; P > 0.05). There was no significant difference in mean signal-to-noise ratio and contrast-to-noise ratio with organ-specific dose reduction (38.3 ± 10.1 and 28.5 ± 8.7, respectively) and without the reduction (35.5 ± 8.5 and 26.5 ± 7.8, respectively) (P > 0.05). Volume computed tomography dose index (CTDIvol) and size-specific dose estimates did not differ significantly between acquisitions with the organ-specific dose reduction (1.7 ± 0.8 mGy) and without the reduction (1.7 ± 0.8 mGy) (P > 0.05).

CONCLUSION

Organ-specific dose reduction does not have an impact on image quality of pediatric chest CT and can therefore be used in clinical practice to reduce radiation dose of radiosensitive organs such as breast and thyroid gland.

[Chest computed tomography in children: indications, efficiency and effective dose]

INTRODUCTION

New multidetector row computed tomography (CT) has made the imaging of younger children more feasible and extending CT indications to a wide range of pediatric respiratory diseases in the last few years. However, CT is a source of radiation exposure. The aim of this study was to evaluate the main indications and the contribution of chest CT in pediatric pulmonology as well as induced radiation.

METHODS

This was an observational, prospective study. Children whose chest CTs were analyzed during multidisciplinary meetings (radiologist, pulmonary pediatrician) were included from November 2009 to April 2010. We collected demographic data, CT results, contribution of CT to diagnosis and management, and radiation doses (dose-length product [DLP] and effective dose). Radiation doses were compared according to the CT scans (Lille University Hospital with 128-slice dual-source CT or Lille University Hospital single-source 64-slice CT, or CT performed outside the university hospital).

RESULTS

One hundred thirty-five patients were included. The mean age was 6.4 years old. The main indications were analysis of bronchial disease (44%), infectious disease (16%), interstitial disease (14%), or a malformation (9%). The aim of CT was diagnosis (61%) or follow-up of previous lung diseases (39%). Diagnosis chest-CT directly contributed to diagnosis in 48% of cases and to treatment in 24%. Follow-up CT contributed to diagnosis in 38% and treatment in 19% of cases. DLP and effective doses were significantly lower for CT performed in the university hospital, especially with the 128-slice CT compared to the others (P<0.001). The effective doses were: 128-slice CT, 0.61 mSv ± 0.32; 64-slice CT, 1.24 mSv ± 0.97; outside university hospital, 2.56 mSv ± 1.98.

CONCLUSION

This study confirms the role played by chest CT in children, which contributes to diagnosis and management of lung diseases. The main concern of CT application, especially in children, is the radiation burden. Children are more susceptible to the effects of radiation than adults and have a longer life expectancy to develop complications. Both radiologists and pediatricians should be aware of a potential risk and have to conjugate their efforts in reducing this risk. The wide range of radiation doses in this study for the same CT procedures underlines the extensive efforts still needed to limit radiation exposure in children.