Pulmonary nodule detection with low-dose CT of the lung: agreement among radiologists.

OBJECTIVE: The purpose of our study was to assess relative intra- and interobserver agreement in detecting pulmonary nodules when interpreting low-dose chest CT screening examinations. MATERIALS AND METHODS: Two hundred ninety-three selected low-dose CT examinations of the lung were independently interpreted by three radiologists to detect and classify pulmonary nodules. The data set selected was enriched with examinations depicting pulmonary nodules. A subset of 30 examinations was interpreted twice. All pulmonary nodules greater than 1.0 mm were marked. All nodules greater than 3.0 mm were marked, measured, and scored as to their probability of being benign or malignant. Nodule-based and examination-based relative reviewer agreements were evaluated using percentage of agreement and kappa statistics. Similar assessments were performed on the subset of examinations interpreted twice. RESULTS: The three radiologists identified a total of 470, 729, and 876 pulmonary nodules of which 395, 641, and 778 were rated as noncalcified with some level of suspicion for being malignant. Nodule-based interobserver agreement among the radiologists was poor (highest kappa value in a paired comparison, 0.120). Examination-based agreement was higher (highest kappa value in a paired comparison, 0.458). Intraobserver agreement was higher than interobserver agreement for examination-based agreement (highest kappa = 0.889) but lower for nodule-based agreement (highest kappa = -0.035). Agreement improved as the suspicion of malignancy increased. CONCLUSION: Unaided intra- and interobserver agreement in detecting pulmonary nodules in low-dose CT of the lung is relatively low. Computer-assisted detection may provide the consistency that is needed for this purpose.

Size and morphology of the trachea before and after lung volume reduction surgery.

OBJECTIVE: The purpose of this investigation was to determine the effect of lung volume reduction surgery on measured tracheal features. MATERIALS AND METHODS: Twenty-four male and 19 female patients with emphysema underwent lung volume reduction surgery, pulmonary function testing, and repeated CT. The tracheal air column was segmented from axial images. The sagittal and coronal dimensions of the intrathoracic trachea were determined. Tracheal morphology was quantified using the tracheal (coronal and sagittal dimensions) and circularity indexes. The results were compared with pulmonary function test results. RESULTS: Morphologic appearance of the intrathoracic trachea was consistent before and 3 months after surgery. The group means of the tracheal length, mean area, and volume were 78.60 mm (+/- 16.88 mm), 283.84 mm(2) (+/- 61.47 mm(2)), and 22.59 cm(3) (+/- 7.69 cm(3)), respectively, before surgery and 67.53 mm (+/- 15.78 mm), 309.12 mm(2) (+/- 79.83 mm(2)), and 20.99 cm(3) (+/- 7.27 cm(3)), respectively, after surgery (p < 0.05). Mean tracheal indexes were 0.85 (+/- 0.11) before surgery and 0.82 (+/- 0.04) after surgery (p < 0.01). Mean circularity indexes were 0.91 (+/- 0.03) before surgery and 0.90 (+/- 0.04) after surgery (p < 0.05). The size of the trachea was significantly correlated with lung volume before and after surgery (p < 0.05). The changes in tracheal features and changes in pulmonary function were not correlated (p > 0.05), except for tracheal area (p < 0.05). CONCLUSION: Our data suggest that tracheal dimensions reflect the severity of emphysema as reflected by increased lung volumes. Tracheal features were poor predictors of changes in postsurgical pulmonary function parameters evaluated in this preliminary study.

Biomechanics of tendons and tendon failure.

Research into the biomechanical properties of tendons had led to a better understanding of the functional and pathophysiologic processes that occur in vivo, particularly in the setting of tendon injury and failure. Increasingly, biomechanical information is being utilized in the clinical setting, guiding patient management in certain circumstances. Differentiating minor and self-limiting abnormalities from those in which specific treatment may prevent further disability from altered biomechanics may become an important role for imaging. This article examines normal tendon anatomy and its relationship to tendon biomechanics under both physiological and pathologic conditions. Imaging characteristics of tendons in the physiologic and pathologic states are discussed. We have focused primarily on MRI, as this modality has been studied most intensively and has been shown to offer additional information regarding unsuspected pathology.

Foot and ankle biomechanics.

With the advent of imaging advancements there has been renewed interest in the foot and ankle. However, many of the basic functions and biomechanical considerations of the bones, joints, and specialized tissues of the normal and dysfunctional foot and ankle remain unfamiliar to many radiologists. This article focuses on the basic biomechanics, normal alignment, and common alignment disorders of the foot and ankle that are relevant to radiologists.

Prevalence effect in a laboratory environment.

PURPOSE: To measure observer performance at various levels of prevalence. MATERIALS AND METHODS: A multiobserver multiabnormality receiver operating characteristic (ROC) study to assess the effect of prevalence on observer performance was conducted. Fourteen observers, including eight faculty members, two fellows, and four residents, interpreted 1,632 posteroanterior chest images with five prevalence levels by using a nested study design. Performance comparisons were accomplished by using a multireader multicase approach to assess the effect of prevalence from 28% (69 of 249) to 2% (31 of 1,577) on diagnostic accuracy. The mean times required to review and report a case were analyzed and compared for different levels of prevalence and readers' experience. RESULTS: Area under the ROC curve demonstrated that, with the study experimental conditions, no significant effect could be measured as a function of prevalence (P >.05) for any abnormality, group of cases, or readers. There were no significant differences (P >.05) in the mean times required to review and report cases at different prevalence levels and with different groups of readers. CONCLUSION: The consistency in the results and the size of this study suggest that with laboratory conditions, if a prevalence effect exists, it is quite small in magnitude; hence, it will not likely alter conclusions derived from such studies.