Three-dimensional volumetric assessment of abnormally low attenuation of the lung from routine helical CT: inspiratory and expiratory quantification.

Chronic obstructive pulmonary disease * 4: Imaging the lungs in patients with chronic obstructive pulmonary disease

“…20 22-31 Three different approaches have mainly been used for objective quantification of emphysema on CT scanning: (1) use of a threshold value below which emphysema is considered to be present (density mask or pixel index (PI)), 20 24 25 (2) assessment of the range of lung densities represented in a lung slice (histogram analysis), 23 27 and (3) assessment of overall lung density, often in combination with volumetric imaging. [28][29][30][31] Müller et al 20 first made use of a standard CT software program called density mask that highlights voxels within any preselected range. They showed that, on conventional 10 mm thick sections, a threshold of -910 HU, which highlights all pixels with attenuation values less than -910, correlates best with the extent of emphysema.…”

“…The development of sophisticated computer programs, coupled with spiral CT scanners, now allows practical quantitative three dimensional (3D) CT assessment of either select regions or entire lung volumes in a single breath hold period. [29][30][31] Using 5 mm and 7 mm collimation with a pitch of 1.5, Park et al 25 found good correlation between 3D assessment of both mean lung attenuation values and frequency distribution histograms of whole lungs compared with routine two dimensional analysis (r=0.98-0.99) and visual scoring (r=0.74-0.82), respectively.…”

Radiograma de tórax e tomografia computadorizada na avaliação do enfisema pulmonar

“…The denomination three-dimensional CT-guided densitometry and volumetric assessment for emphysema (55) has been currently suggested for this quantification process of the volume of emphysema, based on data obtained through spiral CT scan with three-dimensional representation of emphysematous lesions (Figures 5 and 6). The test measures the whole pulmonary volume with abnormal density and, also, the whole lung volume with normal density, (41,(56)(57)(58)(59)(60)(61) setting them apart based on the separation threshold generally selected at −950 HU, as per the suggestion of one author. Among the practical applications of the technique, one study demonstrated that normal CT-guided pulmonary densitometry and volumetric of normal lung and emphysematous areas, or emphysema-like, based on the density measured using Hounsfield scale.…”

Virtual tools for imaging of the thorax

“…With the recent development of lung volume reduction surgery, attempts have been made to use 3D reconstructions of HCT data for quantifying emphysema and evaluating its distribution ( fig. 4) [44][45][46]. In three series, the authors used 3D SSD models of the lungs and various threshold values to select pulmonary parenchyma and emphysema [44][45][46].…”

“…4) [44][45][46]. In three series, the authors used 3D SSD models of the lungs and various threshold values to select pulmonary parenchyma and emphysema [44][45][46]. Their basic idea was that an abnormal emphysematous lung shows lower attenuation than a healthy lung.…”