Early detection of radiation-induced structural changes in rat trabecular bone.
OBJECTIVE
Early detection of bone changes following radiotherapy is very important. The aim of this study is to establish a radiographic image analysis method for early detection of radiation-induced trabecular bone changes.


METHODS
Thirty-five Wistar rats were used for the experimental model of trabecular bone changes, which were induced by X-ray irradiation with 30 Gy to develop simulated osteomyelitis. Standardized 2.2 x direct magnification radiography was performed immediately prior to X-ray irradiation and once a week for 4 weeks following irradiation. The latent X-ray images were scanned using a computed radiography (CR) system. Mathematical morphological processing was then applied to the CR image data, which allowed the bone trabecular pattern features to be extracted as skeletal binary images. The sensitivity and specificity for detecting early trabecular bone changes in CR images and in skeletal binary images were evaluated. Quantitative analyses with quantum level value (QL value), skeletal pixel percentage (SKP) and star volume analysis (skeletal volume (Vsk), skeletal space volume (Vsp)) were performed. Histopathological examination was also conducted for confirmation of physical changes in the bone.


RESULTS
Visual observation of the skeletal binary images provided a higher sensitivity than the CR images. In the quantitative analysis, SKP, Vsk and Vsp values provided higher sensitivity than QL values.


CONCLUSIONS
The results of the present study suggest that a combined radiographic image analysis method using CR, mathematical morphological processing, SKP, Vsk and Vsp can be useful for the early detection of radiation-induced trabecular bone changes.
Kiyohara
S
S
Department of Oral and Maxillofacial Radiology, Kanagawa Dental College, Yokosuka, Japan.
Sakurai
T
T
Kashima
I
I
D000704:Analysis of Variance; D000818:Animals; D001842:Bone and Bones / Q000528:radiation effects*; D008297:Male; D010019:Osteomyelitis / Q000000981:diagnostic imaging*; D011832:Radiation Injuries / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement; D011857:Radiographic Image Interpretation, Computer-Assisted; D051381:Rats; D017208:Rats, Wistar; D012680:Sensitivity and Specificity