COMPARISON OF DIGITIZED AND DIRECT VIEWED (ANALOG) RADIOGRAPHIC IMAGES FOR DETECTION OF PULMONARY NODULES

Interobserver variability of radiographic pulmonary nodule diameter measurements in dogs and cats

The purpose of this study was to determine the interobserver variability of radiographic pulmonary nodule diameter measurements among readers with varying levels of experience. Because interobserver variability may lead to inaccurate estimations of nodule growth on repeat radiographic assessment, an incorrect presumption of malignant etiology or misclassification of tumor response to treatment may result. The maximum diameters of 47 pulmonary nodules from 22 dogs and 7 cats were measured. Measurements were performed using one digital thoracic radiographic projection by eight clinicians. The eight clinicians included two interns, two residents, two board-certified veterinary specialists, and two board-certified veterinary radiologists. A mixed-effect analysis of variance model was used to evaluate the contribution of reader, experience level, patient, nodule, and nodule size to the overall variability in mean pulmonary nodule diameter. The interobserver variability in diameter measurement for any given nodule was 16%, and experience level and nodule size classification did not contribute to measurement variability. Linear measurements of the diameter of a pulmonary nodule can vary significantly among a group of clinicians; however, depending on the criteria used to evaluate nodule growth or tumor response, the 16% interobserver variability reported here is likely not clinically significant.

A Subjective Assessment of Perceived Clarity of Indirect Digital Images and Processed Digital Images with Conventional Intra-oral Periapical Radiographs

OBJECTIVES

To compare and analyze the perceived clarity and diagnostic value of Conventional periapical Radiographs (CRs) with those of their Digitized Periapical Images (DIs) and Processed Digitized Periapical Images (PDIs) counterparts.

MATERIAL AND METHODS

Forty two intraoral periapical radiographs of patients with clinically suspected periapical pathosis were made to constitute the group of CRs. These were photographed by using a Canon Power Shot SD500 (7.1 Megapixel) digital camera and the unaltered images were transferred to a computer laptop, to form the group of DIs. Subsequently, the contrast and brightness of these images were modified to represent the group of PDIs. Two experienced oral radiologists independently evaluated 5 specific apical and periapical region parameters of all the 42 CRs, DIs and PDIs for perceived image quality and diagnostic value and graded them on a three point grading scale. Conventional radiographs served as the control. Data were analyzed by using paired t-test and Kappa analysis.

RESULTS

The clarity and diagnostic quality of the PDIs were statistically significant as compared to those of their conventional counterparts. In comparison, the DIs group fared badly, with deterioration of the image quality. The interobserver agreement was good and all the results were statistically significant.

CONCLUSION

Indirectly digitizing the radiographs by employing a digital camera and further digitally processing the images resulted in an improvement in their perceived clarity and they enhanced their diagnostic properties.

A comparison of computed tomography, computed radiography, and film-screen radiography for the detection of canine pulmonary nodules

Computed tomography (CT) has become more widely available and computed radiography (CR) has replaced film-screen radiography for canine thoracic imaging in many veterinary practices. There are limited data comparing these modalities in a veterinary clinical setting to detect pulmonary nodules. We compared CT, CR, and film-screen radiography for detecting the presence, number, and characteristics of pulmonary nodules in dogs. Observer performance for a variety of experience levels was also evaluated. Twenty-one client-owned dogs with a primary neoplastic process underwent CT and CR; nine also received film-screen radiographs. Positive/negative classification by consensus agreed between the three modalities in 8/9 dogs and between CR and CT in the remaining 12. CT detected the greatest (P = 0.002) total number of nodules and no difference was seen between CR and films. The greatest number of nodules was seen in the right middle and both caudal regions, but only using CT (P < 0.0001). Significantly smaller nodules were detected with CT (P = 0.0007) and no difference in minimum size was detected between CR and films. Observer accuracy was high for all modalities; particularly for CT (90.5-100%) and for the senior radiologist (90.5-100%). CT was also characterized by the least interobserver variability. Although CT, CR, and film-screen performed similarly in determining the presence or absence of pulmonary nodules, a greater number of smaller nodules was detected with CT, and CT was associated with greater diagnostic confidence and observer accuracy and agreement.

Expert interpretation compensates for reduced image quality of camera-digitized images referred to radiologists

We compared the accuracy of five veterinary radiologists when reading 20 radiographic cases on both analog film and in camera-digitized format. In addition, we compared the ability of five veterinary radiologists vs. 10 private practice veterinarians to interpret the analog images. Interpretation accuracy was compared using receiver operating characteristic curve analysis. Veterinary radiologists' accuracy did not significantly differ between analog vs. camera-digitized images (P = 0.13) although sensitivity was higher for analog images. Radiologists' interpretation of both digital and analog images was significantly better compared with the private veterinarians (P < 0.05).