The Sensitivity and Specificity of Using a Computer Aided Diagnosis Program for Automatically Scoring Chest X-Rays of Presumptive TB Patients Compared with Xpert MTB/RIF in Lusaka Zambia

Abstract

ObjectiveTo determine the sensitivity and specificity of a Computer Aided Diagnosis (CAD) program for scoring chest x-rays (CXRs) of presumptive tuberculosis (TB) patients compared to Xpert MTB/RIF (Xpert).MethodConsecutive presumptive TB patients with a cough of any duration were offered digital CXR, and opt out HIV testing. CXRs were electronically scored as normal (CAD score ≤60) or abnormal (CAD score>60) using a CAD program. All patients regardless of CAD score were requested to submit a spot sputum sample for testing with Xpert and a spot and morning sample for testing with LED Fluorescence Microscopy-(FM).ResultsOf 350 patients with evaluable data, 291 (83.1%) had an abnormal CXR score by CAD. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of CXR compared to Xpert were 100% (95%CI 96.2–100), 23.2% (95%CI 18.2–28.9), 33.0% (95%CI 27.6–38.7) and 100% (95% 93.9–100), respectively. The area under the receiver operator curve (AUC) for CAD was 0.71 (95%CI 0.66–0.77). CXR abnormality correlated with smear grade (r = 0.30, p<0.0001) and with Xpert CT(r = 0.37, p<0.0001).ConclusionsTo our knowledge this is the first time that a CAD program for TB has been successfully tested in a real world setting. The study shows that the CAD program had high sensitivity but low specificity and PPV. The use of CAD with digital CXR has the potential to increase the use and availability of chest radiography in screening for TB where trained human resources are scarce.

Perspectives on Advances in Tuberculosis Diagnostics, Drugs, and Vaccines

“…A further development is application of computer-aided image analysis to provide an automated imaging service. Studies suggest that sensitivities from automated readers can be similar to those obtained by eye but that specificity is reduced [27], a finding confirmed by studies in Africa [28,29]. Alternative imaging technologies such as magnetic resonance imaging, computed tomography, and positron emission tomography-computed tomography (PET-CT) may eventually find utility in the investigation of extrapulmonary disease [26].…”

Use of Standardized Uptake Value Ratios Decreases Interreader Variability of [18F] Florbetapir PET Brain Scan Interpretation

“…In this regard, our methodology was similar to that in other studies examining interreader performance in diagnostic imaging with and without an intervention such as computer-aided diagnostic software. Parallel methodology has been used in lung disease, [39][40][41][42][43] breast imaging, 29,[44][45][46] and Alzheimer disease, 26,47 without determining intraobserver variability.…”

Screening for pulmonary tuberculosis in a Tanzanian prison and computer-aided interpretation of chest X-rays

“…14,15 The software ran on the same computer that was used as the viewing station and analysed all images in the background autonomously after initial installation.…”

“…14 Breuninger et al compared it against culture (excluding non-tuberculous mycobacteria, clinically presumed culture-negative cases and extra-pulmonary TB), and reported an AUC of 0.84. 15 The performance of X-ray readers in identifying TB in CXRs was found to be highly variable, and although many studies report high sensitivity (sometimes up to 100%) 24 and low specificity, some authors found the specificity to be higher than the sensitivity.…”

“…Previous studies have established good diagnostic performance of the software Computer Aided Detection for Tuberculosis (CAD4TB, Delft Imaging Systems, Veenendaal, The Netherlands) in a patient population seeking care for TB-related symptoms. [13][14][15] In this study, we examined the potential benefits of CAD4TB when screening a prison population for active PTB and assessed the diagnostic accuracy of CAD4TB in a predominantly asymptomatic prison population. In addition, we recorded parameters to assess the operational feasibility of such screening.…”