Visual grading of emphysema severity in candidates for lung volume reduction surgery. Comparison between HRCT, spiral CT and "density-masked" images.
OBJECTIVE
To investigate which of three types of CT imaging yielded the best results in estimating the degree of emphysema in patients undergoing evaluation for lung volume reduction surgery (LVRS), whether there was any difference in this regard between the cranial and caudal part of the lung, and whether the degree of emphysema had an impact on the estimation.


METHODS
Four radiologists visually classified different degrees of emphysema on three different types of CT images into four groups. The degree of emphysema was calculated by a computer. The three types of images were as follows: HRCT images (2-mm slice thickness); spiral CT images (10-mm slice thickness); and density-masked images (spiral CT images printed with pixels below -960 HU, depicted in white).


RESULTS
The conventionally presented images from HRCT and spiral CT yielded the same results (60% respective 62% correct classifications) in assessing the degree of emphysema irrespective of localisation. Significantly improved results were obtained when the spiral CT images were presented as density-masked images (74%).


CONCLUSIONS
There was no difference between HRCT and spiral CT in assessing the degree of emphysema in candidates for LVRS. Improvement can be achieved by the use of density-masked images.
Cederlund
Kerstin
K
Department of Thoracic Radiology, Karolinska Hospital, SE-171 76 Stockholm, Sweden.
Bergstrand
L
L
Högberg
S
S
Rasmussen
E
E
Svane
B
B
Aspelin
P
P
D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008168:Lung / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011013:Pneumonectomy; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging* / Q000601:surgery*; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed; D014796:Visual Perception