Ultra-low-dose chest computed tomography without anesthesia in the assessment of pediatric pulmonary diseases

Paediatric Thoracic Imaging in Cystic Fibrosis in the Era of Cystic Fibrosis Transmembrane Conductance Regulator Modulation

Cystic fibrosis (CF) is one of the most common progressive life-shortening genetic conditions worldwide. Ground-breaking translational research has generated therapies that target the primary cystic fibrosis transmembrane conductance regulator (CFTR) defect, known as CFTR modulators. A crucial aspect of paediatric CF disease is the development and progression of irreversible respiratory disease in the absence of clinical symptoms. Accurate thoracic diagnostics have an important role to play in this regard. Chest radiographs are non-specific and insensitive in the context of subtle changes in early CF disease, with computed tomography (CT) providing increased sensitivity. Recent advancements in imaging hardware and software have allowed thoracic CTs to be acquired in paediatric patients at radiation doses approaching that of a chest radiograph. CFTR modulators slow the progression of CF, reduce the frequency of exacerbations and extend life expectancy. In conjunction with advances in CT imaging techniques, low-dose thorax CT will establish a central position in the routine care of children with CF. International guidelines regarding the choice of modality and timing of thoracic imaging in children with CF are lagging behind these rapid technological advances. The continued progress of personalised medicine in the form of CFTR modulators will promote the emergence of personalised radiological diagnostics.

Cancer risk in healthy patients who underwent chest tomography comparing three different technologies

This research aimed to estimate the risk of cancer associated with patients without previous disease undergoing chest tomography. Siemens CT scanners have 6, 64, and 128 detectors. The Biologic Effects of Ionizing Radiation Reports - BEIR VII methodology was used. The study presented a sample of 64 patients aged between 18 and 80 years, in the city of Belo Horizonte, Minas Gerais - Brazil. The IMPACT CT software and CalDose X CT Online were used to calculate the absorbed and equivalent dose from the Volumetric Computed Tomography Dose Index - CTDIvol (mGy) and Dose Length Product - DLP values provided by the equipment. CT-Expo Software was also used to estimate Specific Dose Estimates (SSDEs) values. The CTDvol results for the MG1, MG,2 and MG3 Diagnostic Centers in mGy were respectively 4.369 ± 1.352, 6.99 4 ± 1.53,3 and 9.984 ± 2.282 and the SSDE values were 3.800, 6.40,0 and 9,.500. The values for the equivalent dose, at the MG2 Diagnostic Center, by IMPACT CT, in (mSv) for the breasts, esophagus, heart, thyroid, lung and thymus were respectively 3.9, 5.7, 4.7, 1.0, 4.8 and 5.7. The CalDose Software, for the same equipment and the same organs, in mSv, estimated the values 7.4, 9.4, 11.1, 5.3, 10.8 and 11.3 for women and 7.1, 9.3, 11.0, 5.3, 10.2 and 10.9 for men. The estimated risk of cancer decreased according to the patient's age, but with a higher incidence for females. The use of each software must be carefully analyzed to avoid undue values due to the particularities of each one. The results also showed that the risk of developing cancer due to radiation decreases with patient age and is higher in females.

Evaluation of Ultra-Low-Dose Chest Computed Tomography Images in Detecting Lung Lesions Related to COVID-19: A Prospective Study

Background

The present study aimed to evaluate the effectiveness of ultra-low-dose (ULD) chest computed tomography (CT) in comparison with the routine dose (RD) CT images in detecting lung lesions related to COVID-19.

Methods

A prospective study was conducted during April-September 2020 at Shahid Faghihi Hospital affiliated with Shiraz University of Medical Sciences, Shiraz, Iran. In total, 273 volunteers with suspected COVID-19 participated in the study and successively underwent RD-CT and ULD-CT chest scans. Two expert radiologists qualitatively evaluated the images. Dose assessment was performed by determining volume CT dose index, dose length product, and size-specific dose estimate. Data analysis was performed using a ranking test and kappa coefficient (κ). P<0.05 was considered statistically significant.

Results

Lung lesions could be detected with both RD-CT and ULD-CT images in patients with suspected or confirmed COVID-19 (κ=1.0, P=0.016). The estimated effective dose for the RD-CT protocol was 22-fold higher than in the ULD-CT protocol. In the case of the ULD-CT protocol, sensitivity, specificity, accuracy, and positive predictive value for the detection of consolidation were 60%, 83%, 80%, and 20%, respectively. Comparably, in the case of RD-CT, these percentages for the detection of ground-glass opacity (GGO) were 62%, 66%, 66%, and 18%, respectively. Assuming the result of real-time polymerase chain reaction as true-positive, analysis of the receiver-operating characteristic curve for GGO detected using the ULD-CT protocol showed a maximum area under the curve of 0.78.

Conclusion

ULD-CT, with 94% dose reduction, can be an alternative to RD-CT to detect lung lesions for COVID-19 diagnosis and follow-up.An earlier preliminary report of a similar work with a lower sample size was submitted to the arXive as a preprint. The preprint is cited as: https://arxiv.org/abs/2005.03347.