Abstract
Purpose
The authors reviewed chest radiographs (CXR) and thin-section computed tomography (CT) findings of pulmonary complications in a selected population of 50 consecutive patients with severe novel swine-origin influenza A (H1N1) virus (S-OIV) pneumonia who were seen at the Subintensive Respiratory Unit (UTSIR) and at the Intensive Care Unit (ICU) at Monaldi Hospital, Naples, Italy.
Materials and methods
CXR and CT findings of 50 patients who fulfilled the World Health Organisation (WHO) criteria for S-OIV infection were reviewed by four radiologists. The final study group of 50 patients was divided into two subgroups on the basis of clinical course: group 1 consisted of 42 patients requiring noninvasive mechanical ventilation and admitted to the UTSIR; group 2 consisted of eight patients who required ICU admission and extracorporeal membrane oxygenation or advanced mechanical ventilation from October 2009 to December 2009. All patients underwent CXR and thinsection multidetector CT (MDCT) scan; the initial and follow-up radiographs and CT scans were evaluated for the presentation and follow-up pattern (consolidation, groundglass opacities, nodules, reticulation), distribution and extent of abnormality.
Results
All patients had radiological signs of pulmonary involvement. Ground-glass opacity and consolidation, which was mainly peripheral, was the most frequent finding. In three patients, we report for the first time in viral pneumonia the reversed halo sign. Lesion extent was related to aggressiveness of the illness. More often, both lungs were involved (82%). Thoracic comorbidity was present in 18% of patients; 22% of patients was obese, and in this group, the clinical course was more aggressive than in the others with the same lesion extent at imaging. Furthermore, superinfection led to worsening of the clinical conditions.
Conclusions
The most common CXR and CT findings in patients with S-OIV infection were unilateral or bilateral ground-glass opacities with or without associated focal or multifocal areas of consolidation. On MDCT, ground-glass opacities and areas of consolidation had a predominant peribronchovascular and subpleural distribution, resembling organising pneumonia; they progressed to bilateral extensive airspace disease in severely ill patients.
Keywords: Influenza A (H1N1), Viral pneumonia, Reverse halo sign (RHS), Radiology, Computed tomography
Riassunto
Obiettivo
Lo scopo di questo lavoro è stato quello di definire il quadro radiologico (RX) e la semeiotica della tomografia computerizzata (TC) a strato sottile delle complicanze polmonari in una popolazione selezionata di 50 pazienti consecutivi affetti da influenza virale A (H1N1) di origine suina (S-OIV) ricoverati nell’unità di terapia respiratoria subintensiva (UTSIR) e nella terapia intensiva (ICU) dell’Azienda Ospedaliera Monaldi, Napoli, Italia.
Materiali e metodi
Quattro radiologi hanno retrospettivamente esaminato gli esami radiologici tradizionali (RX) e di tomografia computerizzata multidetettore (TCMD) di cinquanta pazienti che rispettavano i criteri della World Health Organization (WHO) per l’influenza A (H1N1) S-OIV. Il gruppo dei 50 pazienti in studio è stato suddiviso in due sottogruppi sulla base del decorso clinico: il gruppo 1, composto da 42 pazienti che hanno richiesto la ventilazione meccanica non invasiva e ricoverati all’UTSIR; il gruppo 2, costituito da 8 pazienti sottoposti a extra corporeal membrane oxygenation (ECMO) o a ventilazione meccanica convenzionale protetta, ricoverati in ICU da ottobre a dicembre 2009. Tutti i pazienti hanno eseguito esami RX e TCMD a strato sottile, di cui è stato valutato il pattern di ingresso e di follow-up (consolidazione, opacità groundglass, noduli e reticolazione interstiziale), la distribuzione e l’estensione delle alterazioni.
Risultati
Tutti i pazienti hanno mostrato segni di interessamento polmonare. L’opacità ground-glass (GGO) e la consolidazione, principalmente periferiche, sono stati i segni più frequenti. Segnaliamo per la prima volta in una polmonite virale in tre pazienti il segno dell’alone invertito (reversed halo sign). L’estensione delle lesioni è risultata correlata all’aggressività clinica della malattia. Nella nostra casistica sono stati spesso (82%) interessati entrambi i polmoni. Il 18% dei pazienti presentava una comorbidità toracica; il 22% di essi era obeso ed in questo gruppo, pur con la stessa estensione delle lesioni all’imaging rispetto ai non obesi, il decorso clinico è stato più aggressivo. Infine la sovra-infezione ha determinato un peggioramento delle condizioni cliniche.
Conclusioni
I segni RX e TCMD più comuni nei pazienti con influenza virale A di origine suina sono rappresentati da opacità GGO uni- o bilaterali con o senza aree di consolidazione focali o multifocali associate. Alla TC le aree GGO e consolidative hanno presentato una distribuzione prevalente subpleurica e peribroncovasale, rassomigliando alla polmonite in organizzazione; in pazienti gravemente malati esse progrediscono ad una malattia consolidativa degli spazi aerei bilaterale ed estesa.
Parole chiave: Influenza A (H1N1), Polmonite virale, Segno dell’alone inverso (RHS), Radiologia, Tomografia computerizzata
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