One-dimensional mean computed tomography value evaluation of ground-glass opacity on high-resolution images.
OBJECTIVE
Differentiation of atypical adenomatous hyperplasia (AAH), bronchioloalveolar carcinoma (BAC), and invasive carcinoma on computed tomography (CT) is useful for determining "follow-up or resection" strategies for lesions displaying ground-glass opacity (GGO). The purpose of this study is to evaluate one-dimensional quantitative CT values of GGO on high-resolution CT (HRCT) images using computer-aided diagnosis.


METHODS
Between April 2001 and March 2010, a total of 44 nodules in 42 patients with pure or mixed GGOs ≤2 cm were retrospectively evaluated. Maximum diameter and one-dimensional mean CT (m-CT) value of the diameter were measured using a computer graphics support system (HOPE/DrABLE-EX, Fujitsu, Tokyo, Japan) that displays a CT density profile across the tumor.


RESULTS
m-CT values were -682 ± 64 HU (range) for AAH lesions, -544 ± 179 (range) for Type A lesions, -496 ± 147 (range) for Type B lesions, and -371 ± 142 (range) for invasive lesions. AAH lesions had a significantly lower m-CT value than Type B lesions. AAH, Type A, and Type B lesions had significantly lower m-CT values than invasive lesions (p < 0.05). All seven GGO lesions with a maximum diameter ≤1 cm and m-CT value ≤-600 HU were pre-invasive lesions, while 16 of 22 (73 %) cases with maximum diameter >1 cm and m-CT value >-600 HU were invasive lesions.


CONCLUSIONS
Observation may be indicated for GGO lesions with a maximum diameter ≤1 cm and m-CT value ≤-600 HU.
Respiratory Disease Center, Showa University Northern Yokohama Hospital, Yokohama, Japan. akitami@med.showa-u.ac.jp
Akihiko
A
Kitami
Yoshito
Y
Kamio
Shoko
S
Hayashi
Kosuke
K
Suzuki
Shugo
S
Uematsu
Ryozo
R
Gen
Takashi
T
Suzuki
Mitsutaka
M
Kadokura
D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000473:pathology; D000077192:Adenocarcinoma of Lung; D002282:Adenocarcinoma, Bronchiolo-Alveolar / Q000000981:diagnostic imaging* / Q000473:pathology; D000236:Adenoma / Q000000981:diagnostic imaging* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006965:Hyperplasia; D007564:Japan; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011237:Predictive Value of Tests; D011379:Prognosis; D011857:Radiographic Image Interpretation, Computer-Assisted; D014057:Tomography, X-Ray Computed