Data di Pubblicazione:
2013
Citazione:
Low-dose CT for quantitative analysis in acute respiratory distress syndrome / V. Vecchi, T. Langer, M. Bellomi, C. Rampinelli, K.K. Chung, L.C. Cancio, L. Gattinoni, A.I. Batchinsky. - In: CRITICAL CARE. - ISSN 1466-609X. - 17:4(2013 Aug 31), pp. R183.1-R183.10.
Abstract:
Introduction: The clinical use of serial quantitative computed tomography (CT) to characterize
lung disease and guide the optimization of mechanical ventilation in patients with acute respiratory
distress syndrome (ARDS) is limited by the risk of cumulative radiation exposure and by the
difficulties and risks related to transferring patients to the CT room. We evaluated the effects of
tube current-time product (mAs) variations on quantitative results in healthy lungs and in
experimental ARDS in order to support the use of low-dose CT for quantitative analysis.
Methods: In 14 sheep chest CT was performed at baseline and after the induction of ARDS via
intravenous oleic acid injection. For each CT session, two consecutive scans were obtained
applying two different mAs: 60 mAs was paired with 140, 15 or 7.5 mAs. All other CT parameters
were kept unaltered (tube voltage 120 kVp, collimation 32x0.5 mm, pitch 0.85, matrix 512x512,
pixel size 0.625x0.625 mm ). Quantitative results obtained at different mAs were compared via
Bland-Altman analysis.
Results: Good agreement was observed between 60 mAs and 140 mAs and between 60 mAs and 15
mAs (all biases less than 1%). A further reduction of mAs to 7.5 mAs caused an increase in the bias
of poorly and non aerated tissue (-2.9 and 2.4%, respectively) and determined a significant
widening of the limits of agreement for the same compartments (-10.5 - 4.8 % for poorly aerated
and -5.9 - 10.8% for non aerated tissue). Estimated mean effective dose at 140, 60, 15 and 7.5 mAs
corresponded to 17.8, 7.4, 2.0 and 0.9 millisievert, respectively. Image noise of scans performed at
140, 60, 15 and 7.5 mAs corresponded to 10, 16, 38 and 74 Hounsfield Units, respectively.
Conclusions: A reduction of effective dose up to 70% has been achieved with minimal effects on
lung quantitative results. Low-dose computed tomography provides accurate quantitative results
and could be used to characterize lung compartment distribution and possibly monitor time-course
of ARDS with a lower risk of exposure to ionizing radiation. A further radiation dose reduction is
associated with lower accuracy in quantitative results.
Tipologia IRIS:
01 - Articolo su periodico
Elenco autori:
V. Vecchi, T. Langer, M. Bellomi, C. Rampinelli, K.K. Chung, L.C. Cancio, L. Gattinoni, A.I. Batchinsky
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