Diagnostic accuracy of 3-T lung magnetic resonance imaging in human immunodeficiency virus-positive children

Impact of Radial Percentage K-Space Filling and Signal Averaging on Native Lung MRI Image Quality in 3D Radial UTE Acquisition: A Pilot Study

RATIONALE AND OBJECTIVE

To assess the impact of radial percentage k-space filling and signal averaging on lung MRI image quality in 3D radial ultrashort echo-time (UTE) acquisition.

MATERIALS AND METHODS

In this IRB approved prospective study, 25 patients (10-30 years) referred for MRI examination for indications other than related to lungs were enrolled from January 2021 to November 2021. All the patients underwent lung MRI, using three different UTE sequence parameters with radial (R) percentage of 100 or 200 and number of signal averages (NSA) of one or two. Two radiologists independently assessed the images for the outline of pleural and mediastinal surface, visibility of lung parenchyma, major bronchi, and segmental bronchi. The quality of the images was assessed based on the degree of motion artifacts. For objective assessment, signal-to-noise ratio, contrast-to-noise ratio, and contrast ratio were calculated.

RESULTS

The outline of pleural and mediastinal surface, lung parenchyma, and segmental bronchi were best demonstrated on R100_NSA2 sequence. The major bronchi were best demonstrated on R100_NSA2 and R100_NSA1 sequences. The intersequence difference was statistically significant for evaluating the pleural and mediastinal surface and segmental bronchi only (p < 0.05). Overall, the best image quality with least artifacts was seen with R100_NSA2 sequence. The objective assessment showed no statistically significant difference between the three sequences (p > 0.05). Interobserver agreement for different findings was substantial to almost perfect for R100_NSA2 and R200_NSA1 sequences.

CONCLUSION

R100_NSA2 UTE sequence performed best for the evaluation of the different findings and showed the best image quality.

Ultrasound and magnetic resonance imaging in thoracic tuberculosis in the pediatric population: moving beyond conventional radiology

Imaging is crucial in the diagnostic work-up and follow-up after treatment in children with thoracic tuberculosis (TB). Despite various technological advances in imaging modalities, chest radiography is the primary imaging modality for initial care and in emergency settings, especially in rural areas and where resources are limited. Ultrasonography (US) of the thorax in TB is one of the emerging applications of US as a radiation-free modality in children. Magnetic resonance imaging (MRI) is the ideal radiation-free, emerging imaging modality for thoracic TB in children. However, only limited published data is available regarding the utility of MRI in thoracic TB. In this pictorial review, we demonstrate the use of US and rapid lung MRI in evaluating children with thoracic TB, specifically for mediastinal lymphadenopathy and pulmonary complications of TB.

Radiological Imaging in Chest Diseases: Moving Away from Conventional Modes

A chest radiograph is the most common and the initial radiological investigation for evaluating a child presenting with respiratory complaints. However, performing and interpreting chest radiography optimally requires training and skill. With the relatively easy availability of computed tomography (CT) scanning and more recently multidetector computed tomography (MDCT), these investigations are often performed. Although these can be the cross-sectional imaging modalities of choice in certain situations where detailed and exact anatomical and etiological information is required, both these investigations are associated with increased radiation exposure which has more detrimental effects on children, especially when repeated follow-up imaging is necessary to assess the disease status. Ultrasonography (USG) and magnetic resonance imaging (MRI) have evolved as radiation-free radiological investigations for evaluating the pediatric chest pathologies over the last few years. In the present review article, the utility and the current status, as well as the limitations of USG and MRI for evaluation of pediatric chest pathologies, are discussed. Radiology has grown beyond having just the diagnostic capabilities in managing children with chest disorders in the last two decades. Image-guided therapeutic procedures (percutaneous and endovascular) are routinely performed in children with pathologies in the mediastinum and lungs. The commonly performed image-guided pediatric chest interventions, including biopsies, fine needle aspiration, drainage procedures and therapeutic endovascular procedures, are also discussed in the current review.

Role of MRI in the Evaluation of Pulmonary Sequel Following COVID-19 Acute Respiratory Distress Syndrome (ARDS)

To evaluate the role of magnetic resonance imaging (MRI) chest as an alternative modality to CT chest for follow-up of patients recovered from severe COVID-19 acute respiratory distress syndrome (ARDS). A total of 25 subjects (16 [64%] men; mean age 54.84 years ± 12.35) who survived COVID-19 ARDS and fulfilled the inclusion criteria were enrolled prospectively. All the patients underwent CT and MRI chest (on the same day) at 6-weeks after discharge. MRI chest was acquired on 1.5T MRI using HASTE, BLADE, VIBE, STIR, and TRUFI sequences and evaluated for recognition of GGOs, consolidation, reticulations/septal thickening, parenchymal bands, and bronchial dilatation with CT chest as the gold standard. The differences were assessed by independent-sample t-test and Mann-Whitney U test. P-value of less than 0.05 was taken significant. There was a strong agreement (k = 0.8-1, P<0.01) between CT and MRI chest. On CT, the common manifestations were: GGOs (n=24, 96%), septal thickening/reticulations (n=24, 96%), bronchial dilatation (n=16, 64%), parenchymal bands (n=14, 56%), pleural thickening (n=8, 32%), consolidation (n=4, 16%) and crazy-paving (n=4, 16%). T2W HASTE, T2W BLADE, and T1 VIBE sequences showed 100% (95% CI, 40-100) sensitivity and 100% (95% CI, 3-100) specificity for detecting GGOs, septal thickening/reticulations, pleural thickening, consolidation, and crazy-paving. The overall sensitivity of MRI for detection of bronchial dilatation and parenchymal bands were 88.9% (95% CI, 77-100) and 92.9% (95% CI, 66-100), respectively; and specificity was 100% (95% CI, 29-100) for both findings. MRI chest, being radiation-free imaging modality can act as an alternative to CT chest in the evaluation of lung changes in patients recovered from COVID-19 pneumonia.

Comparison Between Magnetic Resonance Imaging and Computed Tomography in the Detection and Volumetric Assessment of Lung Nodules: A Prospective Study

Rationale and Objectives

Computed tomography (CT) lung nodule assessment is routinely performed and appears very promising for lung cancer screening. However, the radiation exposure through time remains a concern. With the overall goal of an optimal management of indeterminate lung nodules, the objective of this prospective study was therefore to evaluate the potential of optimized ultra-short echo time (UTE) MRI for lung nodule detection and volumetric assessment.

Materials and Methods

Eight (54.9 ± 13.2 years) patients with at least 1 non-calcified nodule ≥4 mm were included. UTE under high-frequency non-invasive ventilation (UTE-HF-NIV) and in free-breathing at tidal volume (UTE-FB) were investigated along with volumetric interpolated breath-hold examination at full inspiration (VIBE-BH). Three experienced readers assessed the detection rate of nodules ≥4 mm and ≥6 mm, and reported their location, 2D-measurements and solid/subsolid nature. Volumes were measured by two experienced readers. Subsequently, two readers assessed the detection and volume measurements of lung nodules ≥4mm in gold-standard CT images with soft and lung kernel reconstructions. Volumetry was performed with lesion management software (Carestream, Rochester, New York, USA).

Results

UTE-HF-NIV provided the highest detection rate for nodules ≥4 mm (n = 66) and ≥6 mm (n = 32) (35 and 50%, respectively). No dependencies were found between nodule detection and their location in the lung with UTE-HF-NIV (p > 0.4), such a dependency was observed for two readers with VIBE-BH (p = 0.002 and 0.03). Dependencies between the nodule's detection and their size were noticed among readers and techniques (p < 0.02). When comparing nodule volume measurements, an excellent concordance was observed between CT and UTE-HF-NIV, with an overestimation of 13.2% by UTE-HF-NIV, <25%-threshold used for nodule's growth, conversely to VIBE-BH that overestimated the nodule volume by 28.8%.

Conclusion

UTE-HF-NIV is not ready to replace low-dose CT for lung nodule detection, but could be used for follow-up studies, alternating with CT, based on its volumetric accuracy.

Practical protocol for lung magnetic resonance imaging and common clinical indications

Imaging speed, spatial resolution and availability have made CT the favored cross-sectional imaging modality for evaluating various respiratory diseases of children - but only for the price of a radiation exposure. MRI is increasingly being appreciated as an alternative to CT, not only for offering three-dimensional (3-D) imaging without radiation exposure at only slightly inferior spatial resolution, but also for its superior soft-tissue contrast and exclusive morpho-functional imaging capacities beyond the scope of CT. Continuing technical improvements and experience with this so far under-utilized modality contribute to a growing acceptance of MRI for an increasing number of indications, in particular for pediatric patients. This review article provides the reader with practical easy-to-use protocols for common clinical indications in children. This is intended to encourage pediatric radiologists to appreciate the new horizons for applications of this rapidly evolving technique in the field of pediatric respiratory diseases.

Chest MRI as an emerging modality in the evaluation of empyema in children with specific indications: Pilot study

OBJECTIVES

To assess the diagnostic role of chest magnetic resonance imaging (MRI) for evaluating empyema in children with specific indications.

METHODS

Nineteen children (5-16 years) with a diagnosis of empyema were enrolled in this prospective study from January 2018 to February 2020. MRI and multidetector computed tomography (MDCT) of the chest was performed within 48 h of each other. Two pediatric radiologists independently evaluated the MRI and CT images for the presence of fluid and air in the pleural cavity, septations within the fluid, pleural thickening, pleural enhancement, drainage tube tip localization, consolidation, and lymphadenopathy. Kappa test of agreement was used to determine the agreement between the MRI and MDCT findings. Chance-corrected kappa statistics were used for calculating the interobserver variation.

RESULTS

The kappa test showed almost perfect agreement (κ = 1) between MRI and MDCT for detecting fluid, pleural thickening, pleural enhancement, drainage tube tip localization, consolidation, and lymphadenopathy. Septations within the fluid were detected in 16 (84.2%) patients on MRI, and in 14 (73.7%) patients on MDCT. Almost perfect agreement (κ = 0.81-1.00) was seen for all the findings on CT and MRI between the two radiologists, except for pleural thickening for which a strong agreement (κ = 0.642) was observed.

CONCLUSION

MRI is comparable to MDCT for the detection of various findings in children with empyema. MRI may be considered in lieu of CT, as a problem-solving tool and as a radiation-reducing endeavor in children with empyema, specifically, only where CT is required for preoperative planning and evaluation of complications.

Lung MRI in Children: The Road Less Travelled

Magnetic resonance imaging (MRI) of the lungs is one of the most underutilized imaging modality when it comes to imaging of thoracic diseases in children. This is largely due to less-than-optimal image quality and multiple technical challenges involved with MRI of the lungs. Advances in MRI technology along with increased awareness about optimization of MR protocol have led to it being viewed as a feasible option for evaluation of various chest diseases in children. This short review article takes the reader to the road less travelled to explore newer horizons for applications of this rapidly evolving magnetic resonance technique in the field of thoracic diseases in children.

New Insight into Laboratory Tests and Imaging Modalities for Fast and Accurate Diagnosis of COVID-19: Alternative Suggestions for Routine RT-PCR and CT-A Literature Review

The globally inimitable and unremitting outbreak of COVID-19 infection confirmed the emergency need for critical detection of human coronavirus infections. Laboratory diagnostic tests and imaging modalities are two test groups used for the detection of COVID-19. Nowadays, real-time polymerase chain reaction (RT-PCR) and computed tomography (CT) have been frequently utilized in the clinic. Some limitations that confront with these tests are false-negative results, tests redone for follow-up procedure, high cost, and unable to do for all patients. To overcome these limitations, modified and alternative tests must be considered. Among these tests, RdRp/Hel RT-PCR assay had the lowest diagnostic limitation and highest sensitivity and specificity for the detection of SARS-CoV-2 RNA in both respiratory tract and nonrespiratory tract clinical specimens. On the other hand, lung ultrasound (LUS) and magnetic resonance imaging (MRI) are CT-alternative imaging modalities for the management, screening, and follow-up of COVID-19 patients.

Quantitative CT analysis for bronchiolitis obliterans in perinatally HIV-infected adolescents-comparison with controls and lung function data

OBJECTIVE

To compare quantitative chest CT parameters in perinatally HIV-infected adolescents with and without bronchiolitis obliterans compared with HIV-uninfected controls and their association with lung function measurements.

MATERIALS AND METHODS

Seventy-eight (41 girls) HIV-infected adolescents with a mean age of 13.8 ± 1.65 years and abnormal pulmonary function tests in the prospective Cape Town Adolescent Antiretroviral Cohort underwent contrast-enhanced chest CT on inspiration and expiration. Sixteen age-, sex-, and height-matched non-infected controls were identified retrospectively. Fifty-one HIV-infected adolescents (28 girls) displayed mosaic attenuation on expiration suggesting bronchiolitis obliterans. Pulmonary function tests were collected. The following parameters were obtained: low- and high-attenuation areas, mean lung density, kurtosis, skewness, ventilation heterogeneity, lung mass, and volume.

RESULTS

HIV-infected adolescents showed a significantly higher mean lung density, ventilation heterogeneity, mass, and high- and low-attenuation areas compared with non-infected individuals. Kurtosis and skewness were significantly lower as well. HIV-infected adolescents with bronchiolitis obliterans had a significantly lower kurtosis and skewness compared with those without bronchiolitis obliterans. Lung mass and volume showed the strongest correlations with forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), and alveolar volume. Low-attenuation areas below - 950 HU and ventilation heterogeneity showed the strongest correlation with FEV₁/FVC (range, - 0.51 to - 0.34) and forced expiratory flow between 25 and 75% of FVC (range, - 0.50 to - 0.35).

CONCLUSION

Quantitative chest CT on inspiration is a feasible technique to differentiate perinatally HIV-infected adolescents with and without bronchiolitis obliterans. Quantitative CT parameters correlate with spirometric measurements of small-airway disease.

KEY POINTS

• Perinatally HIV-infected adolescents showed a more heterogeneous attenuation of the lung parenchyma with a higher percentage of low- and high-attenuation areas compared with non-infected patients. • Kurtosis and skewness are able to differentiate between HIV-infected adolescents with and without bronchiolitis obliterans using an inspiratory chest CT. • Quantitative CT parameters of the chest correlate significantly with pulmonary function test. Low-attenuation areas and ventilation heterogeneity are particularly associated with spirometric parameters related to airway obstruction.