Determinants of radiological patterns and severity in immunocompromised adults with Metapneumovirus infection

BACKGROUND

Human Metapneumovirus (HMPV) belongs to the Pneumoviridae family and is responsible for respiratory infections. Mild infections are well-recognized in children, while its precise impact in various categories of immunocompromised adults has not been well addressed.

RESEARCH QUESTION

We retrospectively studied HMPV infections in immunocompromised adults followed in two large French university medical centers.

STUDY DESIGN AND METHODS

We identified immunocompromised adults with positive HMPV Polymerase Chain Reaction (PCR) for 36 months and reviewed their medical charts. For lung transplant recipients (LTR), FEV1 was collected at baseline, during and after infection. Imaging was centralized and chest involvement was categorized by dominant CT patterns. We compared severe patients (requiring oxygen or ventilation) and non hypoxemic patients.

RESULTS

Seventy-two patients were included, 27 were LTR, 25 had a hematological malignancy or were hematopoietic stem cell recipients, 20 had another immunocompromised status. Twenty patients (28%) presented a hypoxemic infection, requiring hospitalization and intensive care units transfers in 50/72 (69.4%) and 9/72 (12.5%) respectively, with only one death. Hypoxemia was less pronounced in LTRs (p = 0.014). Finally, age and dyspnea remained independent factors associated with hypoxemia (p < 0.005). The most frequent radiological patterns were bronchopneumonia (34.2%) and bronchiolitis (39.5% and 64.3% in the overall population and in LTRs respectively, p = 0.045). FEV1 improved in LTRs at one month and 85% had recovered their baseline FEV1 within 6 months.

INTERPRETATIONS

In immunocompromised adults, HMPV infections required frequent hospitalizations and ICU transfers, while mortality is low. In LTRs, bronchiolitis pattern was predominant with short and long-term favorable outcome.

[The contribution of artificial intelligence (AI) subsequent to the processing of thoracic imaging]

The contribution of artificial intelligence (AI) to medical imaging is currently the object of widespread experimentation. The development of deep learning (DL) methods, particularly convolution neural networks (CNNs), has led to performance gains often superior to those achieved by conventional methods such as machine learning. Radiomics is an approach aimed at extracting quantitative data not accessible to the human eye from images expressing a disease. The data subsequently feed machine learning models and produce diagnostic or prognostic probabilities. As for the multiple applications of AI methods in thoracic imaging, they are undergoing evaluation. Chest radiography is a practically ideal field for the development of DL algorithms able to automatically interpret X-rays. Current algorithms can detect up to 14 different abnormalities present either in isolation or in combination. Chest CT is another area offering numerous AI applications. Various algorithms have been specifically formed and validated for the detection and characterization of pulmonary nodules and pulmonary embolism, as well as segmentation and quantitative analysis of the extent of diffuse lung diseases (emphysema, infectious pneumonias, interstitial lung disease). In addition, the analysis of medical images can be associated with clinical, biological, and functional data (multi-omics analysis), the objective being to construct predictive approaches regarding disease prognosis and response to treatment.

[Bronchiectasis imaging]

Bronchiectasis are defined as an irreversible focal or diffuse dilatation of the bronchi and can be associated with significant morbidity. The prevalence is currently increasing, probably due to an increased use of thoracic computed tomography (CT). Indeed, the diagnosis relies on imaging and chest CT is the gold standard technique. The main diagnosis criterion is an increased bronchial diameter as compared to that of the companion artery. However, false positives are possible when the artery diameter is decreased, which is called pseudo-bronchiectasis. Other features such as the lack of bronchial tapering, and visibility of bronchi within 1cm of the pleural surface are also diagnostic criteria, and other CT features of bronchial disease are commonly seen. Thoracic imaging also allows severity assessment and long-term monitoring of structural abnormalities. The distribution pattern and the presence of associated findings on chest CT help identifying specific causes of bronchiectasis. Lung MRI and ultra-low dose CT and are promising imaging modalities that may play a role in the future. The objectives of this review are to describe imaging features for the diagnosis and severity assessment of bronchiectasis, to review findings suggesting the cause of bronchiectasis, and to present the new developments in bronchiectasis imaging.

[Allergic bronchopulmonary aspergillosis: Evaluation of a maintenance therapy with nebulized Ambisome®]

BACKGROUND

Allergic bronchopulmonary aspergillosis (ABPA) affects 3-13% of patients with asthma. Its natural history includes possibly life-threatening exacerbations and evolution towards fixed obstructive ventilatory disorders or even irreversible lung fibrosis lesions. ABPA prognosis is directly associated with exacerbation control and the main objective of the treatment is to decrease their frequency and duration. Recommendations regarding dosage and duration of treatment are not very precise. The currently used combination of itraconazole and corticosteroid therapy has many limitations. The interests of a therapeutic strategy using nebulized liposomal amphotericin B (LAmB) are to heighten antifungal lung tissue concentration, to circumvent drug interactions and decrease the potential toxicity of systemic antifungal treatments. Finally, this association leads to improved eradication of Aspergillus, thereby limiting the risk of side effects and the emergence of treatment-resistant Aspergillus strains.

METHODS

This is a phase II, multicentre, randomized, single blind, controlled therapeutic study, with the objective of comparing the potential benefit on exacerbation control of a maintenance therapy by LAmB nebulization. The main objective of the study is to compare the incidence of severe clinical exacerbations in ABPA treatment, between a maintenance treatment strategy with nebulized LAmB and a conventional strategy without antifungal maintenance therapy.

EXPECTED RESULTS

The results will guide practitioners in the management of ABPA treatments and help to define the place of aerosols of LAmB on "evidence base medicine" criteria.

[Chest trauma: spectrum of lesions]

Blunt chest trauma typically occurs as part of polytrauma, usually secondary to motor vehicle accidents, sports related injuries or defenestration in Western Europe. Each chest compartment may be responsible for immediate and/or delayed complications, thus requiring a dedicated systematic and comprehensive analysis. The use of image post-processing is mandatory in order to not overlook a potentially severe injury. The purpose of this paper is to review the technical considerations of multidetector CT, and the imaging features and interpretation method for each chest compartment, in order to generate an adapted report.

[Rhinocerebral mucormycosis]

We report a case of a rhinocerebral mucormycosis with extensive cavernous sinus thrombophlebitis and internal carotid artery thrombosis. This case illustrates the usual clinical and imaging features of the disease, which is a potentially devastating infection in immunocompromised patients.