Abstract
ObjectiveChest radiographs (CXR) are an important diagnostic tool for the detection of invasive pulmonary aspergillosis (IPA) in critically ill patients, but their diagnostic value is limited by a poor sensitivity. By using advanced image processing, the aim of this study was to increase the value of chest radiographs in the diagnostic work up of neutropenic patients who are suspected of IPA.MethodsThe frontal CXRs of 105 suspected cases of IPA were collected from four institutions. Radiographs could contain single or multiple sites of infection. CT was used as reference standard. Five radiologists and two residents participated in an observer study for the detection of IPA on CXRs with and without bone suppressed images (ClearRead BSI 3.2; Riverain Technologies). The evaluation was performed separately for the right and left lung, resulting in 78 diseased cases (or lungs) and 132 normal cases (or lungs). For each image, observers scored the likelihood of focal infectious lesions being present on a continuous scale (0–100). The area under the receiver operating characteristics curve (AUC) served as the performance measure. Sensitivity and specificity were calculated by considering only the lungs with a suspiciousness score of greater than 50 to be positive.ResultsThe average AUC for only CXRs was 0.815. Performance significantly increased, to 0.853, when evaluation was aided with BSI (p = 0.01). Sensitivity increased from 49% to 66% with BSI, while specificity decreased from 95% to 90%.ConclusionThe detection of IPA in CXRs can be improved when their evaluation is aided by bone suppressed images. BSI improved the sensitivity of the CXR examination, outweighing a small loss in specificity.
Highlights
Invasive pulmonary aspergillosis (IPA) is a major cause of morbidity and mortality, in patients with hematological malignancies [1,2,3]
The imaging criteria of the EORTC/MSG guidelines for the presence of IPA refer to specific Computed Tomography (CT) findings and the guidelines published by the Infectious Diseases Working Party of the German Society of Haematology and Oncology (AGIHO) in 2012 state that in patients with granulocytopenia, high resolution computed tomography (HRCT) should be preferred to chest x-ray for primary diagnosis in high-risk patients [11]
Neutropenic patients with signs of fever with a normal chest radiograph functioned as control subjects
Summary
Invasive pulmonary aspergillosis (IPA) is a major cause of morbidity and mortality, in patients with hematological malignancies [1,2,3]. While a proven diagnosis requires histological and/or cultural evidence from tissue specimen or positive cultures from body fluids, these criteria are often not met and not applicable at an early stage of infection This discrepancy between definite diagnostic proof of IPA on one side and the need for treatment as early as possible on the other side has led to different therapeutic strategies ranging from prophylaxis to empirical therapy of persistent neutropenia to pre-emptive approaches of very early, still preclinical disease [9]. In this diagnostic dilemma, imaging still plays an important role. The imaging criteria of the EORTC/MSG guidelines for the presence of IPA refer to specific CT findings (dense well circumscribed lesions with or without a halo sign, air crescent sign, cavity) and the guidelines published by the Infectious Diseases Working Party of the German Society of Haematology and Oncology (AGIHO) in 2012 state that in patients with granulocytopenia, high resolution computed tomography (HRCT) should be preferred to chest x-ray for primary diagnosis in high-risk patients [11]
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