Abstract
Purpose
The aim of this study was to assess the accuracy of some computed tomography (CT) quantitative indices (histogram features, ranges of density and one novel volumetric index) in the discrimination between normals and patients affected by lung fibrosis, and to compare their morphologic-functional relationship with the visual score one.
Materials and methods
We analysed thin-section CTs and pulmonary function tests (PFTs) of six healthy subjects and 31 patients affected by lung fibrosis, including 17 with a usual interstitial pneumonia pattern (UIP group), and 14 with a predominant pattern of ground-glass opacities without honeycombing (non-UIP group). Presence and extent of various CT findings were assessed by the visual score as well as by CT computer indices.
Results
Together with the histogram features, fibrosis ratio (defined as the ratio of nonfibrotic CT lung volume divided by total CT lung volume) contributed to objectively differentiate fibrotic lungs from normal lungs. The range of density 700 to 400 HU showed the greatest degree of correlation with physiologic abnormality in the non-UIP group. In the UIP group, the lone visual score provided prediction of functional impairment.
Conclusions
The visual score is still the main radiological method of quantifying the extent of abnormalities in patients with UIP, whilst the range of density 700 to 400 HU can be helpfully applied in a predominant pattern of ground-glass and reticular opacities without honeycombing.
Riassunto
Obiettivo
Valutare l’accuratezza di alcuni indici quantitativi utilizzati in tomografia computerizzata (TC) (istogrammi, intervalli di densità ed indici volumetrici) nel discriminare pazienti normali da pazienti affetti da fibrosi polmonare e confrontare la loro relazione morfologica-funzionale con lo score visivo.
Materiali e methodi
Abbiamo analizzato scansioni TC a strato sottile di sei soggetti sani e di 31 pazienti con fibrosi polmonare, compresi 17 con un pattern di polmonite interstiziale usuale (gruppo di UIP) e 14 con un pattern predominante di ground-glass senza honey-combing (gruppo non-UIP). La presenza e l’estensione dei vari reperti TC sono stati valutati sia con score visivo che con indici TC quantitativi.
Risultati
Insieme agli istogrammi, l’indice fibrotico volumetrico (definito come il rapporto tra il volume di polmone non fibrotico e il volume polmonare totale) ha contributio nel differenziare in modo obiettivo i polmoni fibrotici dai polmoni normali. Il range di densità −700–400 HU ha mostrato la maggiore correlazione con i parametri funzionali nel gruppo dei pazienti non-UIP. Nel gruppo UIP, solo lo score visivo ha fornito una corretta previsione del danno funzionale.
Conclusioni
Lo score visivo è ancora il metodo radiologico principale per quantificare l’estensione della patologia in pazienti con UIP, mentre l’intervallo di densità −700–400 HU può essere vantaggiosamente applicato in un pattern predominante a ground-glass e reticolare senza honey-combing.
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Sverzellati, N., Calabrò, E., Chetta, A. et al. Visual score and quantitative CT indices in pulmonary fibrosis: Relationship with physiologic impairment. Radiol med 112, 1160–1172 (2007). https://doi.org/10.1007/s11547-007-0213-x
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DOI: https://doi.org/10.1007/s11547-007-0213-x