Diagnostic accuracy of computer-aided detection of pulmonary tuberculosis in chest radiographs : a validation study from sub-saharan Africa

Chest radiography to diagnose and screen for pulmonary tuberculosis has limitations, especially due to inter-reader variability. Automating the interpretation has the potential to overcome this drawback and to deliver objective and reproducible results. The CAD4TB software is a computer-aided detection system that has shown promising preliminary findings. Evaluation studies in different settings are needed to assess diagnostic accuracy and practicability of use.; CAD4TB was evaluated on chest radiographs of patients with symptoms suggestive of pulmonary tuberculosis enrolled in two cohort studies in Tanzania. All patients were characterized by sputum smear microscopy and culture including subsequent antigen or molecular confirmation of Mycobacterium tuberculosis (M.tb) to determine the reference standard. Chest radiographs were read by the software and two human readers, one expert reader and one clinical officer. The sensitivity and specificity of CAD4TB was depicted using receiver operating characteristic (ROC) curves, the area under the curve calculated and the performance of the software compared to the results of human readers.; Of 861 study participants, 194 (23%) were culture-positive for M.tb. The area under the ROC curve of CAD4TB for the detection of culture-positive pulmonary tuberculosis was 0.84 (95% CI 0.80-0.88). CAD4TB was significantly more accurate for the discrimination of smear-positive cases against non TB patients than for smear-negative cases (p-value>0.01). It differentiated better between TB cases and non TB patients among HIV-negative compared to HIV-positive individuals (p>0.01). CAD4TB significantly outperformed the clinical officer, but did not reach the accuracy of the expert reader (p = 0.02), for a tuberculosis specific reading threshold.; CAD4TB accurately distinguished between the chest radiographs of culture-positive TB cases and controls. Further studies on cost-effectiveness, operational and ethical aspects should determine its place in diagnostic and screening algorithms

Flow chart of individuals taking part in the study.

<p>Flow chart of individuals taking part in the study.</p

ROC analysis for the detection of M.tb culture-positive individuals.

<p>Legend. <b>—–</b>A (s+/c+ M.tb), B (s−/c+ M.tb) vs. F (Controls): A_z = 0.84 (0.80–0.88), <b>- - -</b> A (s+/c+ M.tb), B (s−/c+ M.tb) vs. C (s±/c+ NTM), E (EPTB), F (Controls): A_z = 0.81 (0.77–0.85), p = 0.28.</p

Classification of study population according to clinical and microbiological data.

<p>Classification of study population according to clinical and microbiological data.</p

Distribution of CAD scores for patient groups A (s+/c+ M.tb), B (s−/c+ M.tb), C (s±/c+ NTM), D (s−/c− clin.TB) and F (Controls).

<p>Distribution of CAD scores for patient groups A (s+/c+ M.tb), B (s−/c+ M.tb), C (s±/c+ NTM), D (s−/c− clin.TB) and F (Controls).</p

Median CAD scores and 90% central range.

<p>Median CAD scores and 90% central range.</p

Summary statistics of study population.

1<p>standard deviation.</p><p>Summary statistics of study population.</p

Performance of CAD4TB and human readers.

1<p>sensitivity²specificity ³positive predictive value ⁴negative predictive value ⁵positive likelihood ratio ⁶negative likelihood ratio. All parameters were assessed against group A and B as positive reference standard and group F as negative controls.</p><p>Performance of CAD4TB and human readers.</p

A cultural meaning of The New Yorker ‘Lawyer cartoon’

This essay concerns itself with the Lawyer cartoon, a thematic subgenre of the ‘‘The New Yorker Magazine’’ cartoon, which focuses on the legal profession in the US context. An examination of the cultural meaning of this phenomenon is carried out on the strength of ethnography of communication, which discloses the cartoon as a cultural, social and rhetorical artifact. Among the findings of this study are the structural components, functions, and the rules of configuring the Lawyer cartoon toward it becoming a matter of ‘‘risibility’’ as well as a matter of cultural symbolism. By presenting the attorney as an abnormal character with excessive and hypocritical characteristics, the Lawyer cartoon points to the ascriptions of a disrupted self, making the profession appear as fundamentally inauthentic