EARLY DETECTION OF PNEUMONIA IN FEBRILE NEUTROPENIC PATIENTS - USE OFTHIN-SECTION CT

OBJECTIVE. The purpose of this study was to evaluate the usefulness of thin-section CT for early detection of pneumonia in neutropenic patie nts with an unknown site of infection and normal or nonspecific findin gs on chest radiographs.SUBJECTS AND METHODS. Eighty-seven patients wi th febrile neutropenia that persisted for more than 2 days despite emp iric antibiotic treatment underwent 146 prospective examinations. If f indings on chest radiographs were normal (n = 126) or nonspecific (n = 20), thin-section CT (1-mm collimation, 10-mm increment) was done. If thin-section CT scans showed opacities, bronchoalveolar lavage was re commended. RESULTS. Findings on chest radiographs were nonspecific for pneumonia in 20 (14%) of 146 cases, and CT findings in those cases we re suggestive of pneumonia. Microorganisms were detected in Il of thos e 20 cases. Seven of the 11 cases were not optimally treated before CT diagnosis, the other four were sufficiently treated. Findings on ches t radiographs and thin-section CT scans were normal in 56 (38%) of 146 cases. In 70 (48%) of 146 cases, findings on chest radiographs were n ormal, whereas findings on thin-section CT scans were suggestive of pn eumonia. Microorganisms were detected in 30 of the 70 cases. Nineteen of 30 cases were not optimally treated before CT, whereas the other 11 cases were sufficiently treated before CT. In 22 (31%) of these 70 ca ses, an opacity was observed on the chest radiograph during the 7 days after the CT study. Only three (5%) of 56 pneumonias occurred during the first 7 days after thin-section CT studies with normal findings (p < .005). Additional risk factors for pneumonia occurring later that w ere detectable on chest radiographs were poorly defined nodules (p < . 05), consolidation (p < .05), and younger age (p < .05). CONCLUSION. T hin-section CT scans show findings suggestive of pneumonia about 5 day s earlier than chest radiographs show suggestive findings. When thin-s ection CT scans show findings suggestive of pneumonia, the probability of pneumonia being detected on chest radiographs during the 7-day fol low-up is 31%, whereas the probability is only 5% when the findings on the prior thin-section CT scan were normal (p < .005). All neutropeni c patients with fever of unknown origin and normal findings on chest r adiographs should be examined with thin-section CT.