The effects of ambient lighting in chest radiology reading rooms.

Under typical dark chest radiography reading room conditions, a radiologist's pupils contract and dilate as their visual focus intermittently shifts between the high luminance monitor and the darker background wall, resulting in increased visual fatigue and degradation of diagnostic performance. A controlled increase of ambient lighting may minimize these visual adjustments and potentially improve comfort and accuracy. This study was designed to determine the effect of a controlled increase of ambient lighting on chest radiologist nodule detection performance. Four chest radiologists read 100 radiographs (50 normal and 50 containing a subtle nodule) under low (E=1 lx) and elevated (E=50 lx) ambient lighting levels on a DICOM-calibrated, medical-grade liquid crystal display. Radiologists were asked to identify nodule locations and rate their detection confidence. A receiver operating characteristic (ROC) analysis of radiologist results was performed and area under ROC curve (AUC) values calculated for each ambient lighting level. Additionally, radiologist selection times under both illuminance conditions were determined. Average AUC values did not significantly differ (p>0.05) between ambient lighting levels (estimated mean difference=-0.03; 95% CI, (-0.08, 0.03)). Average selection times decreased or remained constant with increased illuminance. The most considerable decreases occurred for false positive identification times (35.4±18.8 to 26.2±14.9 s) and true positive identification times (29.7±18.3 to 24.5±15.5 s). No performance differences were statistically significant. Study findings suggest that a controlled increase of ambient lighting within darkly lit chest radiology reading rooms, to a level more suitable for performance of common radiological tasks, does not appear to have a statistically significant effect on nodule detection performance.

Nonsurgical extracardiac vascular shunts in the thorax: clinical and imaging characteristics.

Extracardiac nonsurgical vascular shunts in the thorax are a group of well-recognized heterogeneous conditions, frequently symptomatic, in which there is diversion of blood flow from one vessel to another or from a vessel to a cardiac chamber. The authors describe and classify many of these nonsurgical extracardiac shunts or fistulas according to their source and endpoint (eg, systemic-to-systemic, systemic-to-pulmonic, pulmonic-to-systemic, and pulmonic-to-pulmonic) and to whether the oxygenated blood mixes with deoxygenated systemic venous flow (left-to-right shunts), deoxygenated blood bypasses the pulmonary capillary bed (right-to-left shunts), or oxygenated blood recirculates (left-to-left shunts). Clinical manifestations and imaging appearances of these conditions are highlighted.

Mucoid impactions: finger-in-glove sign and other CT and radiographic features.

Mucoid impaction is a relatively common finding at chest radiography and computed tomography (CT). Both congenital and acquired abnormalities may cause mucoid impaction of the large airways that often manifests as tubular opacities known as the finger-in-glove sign. The congenital conditions in which this sign most often appears are segmental bronchial atresia and cystic fibrosis. The sign also may be observed in many acquired conditions, include inflammatory and infectious diseases (allergic bronchopulmonary aspergillosis, broncholithiasis, and foreign body aspiration), benign neoplastic processes (bronchial hamartoma, lipoma, and papillomatosis), and malignancies (bronchogenic carcinoma, carcinoid tumor, and metastases). To point to the correct diagnosis, the radiologist must be familiar with the key radiographic and CT features that enable differentiation among the various likely causes. CT is more useful than chest radiography for differentiating between mucoid impaction and other disease processes, such as arteriovenous malformation, and for directing further diagnostic evaluation. In addition, knowledge of the patient's medical history, clinical symptoms and signs, and predisposing factors is important.

PET imaging in patients with bronchioloalveolar cell carcinoma.

OBJECTIVE: Focal bronchioloalveolar cell carcinoma (BAC) has been reported as often being negative on 2-[fluorine-18] fluoro-2-deoxy-D-glucose (FDG-PET) scans, but no studies have examined the FDG-PET findings of both the focal and multifocal forms of the disease. The purpose of this study was to examine the sensitivity of PET in detecting both forms of BAC. MATERIALS AND METHODS: A retrospective review of our tumor registry revealed 15 patients who had pathologically proved BAC and who had undergone FDG-PET imaging. FDG-PET scans were interpreted as positive if the tumor demonstrated activity that was greater than the mediastinal blood pool. RESULTS: Eight patients had focal BAC, and seven patients had multifocal disease. Nine of the 15 patients (60%) had a positive PET scan, and of these, six (67%) had multifocal disease. Six of the 15 patients (40%) had negative PET scans, and of these, five patients (83%) had the solitary form of disease. The sensitivity for focal tumors was 38%, and the sensitivity for the multifocal form was 86%. CONCLUSIONS: Our data confirm previous reports describing a high percentage of false negative PET scans in the setting of focal BAC. However, in the presence of multifocal disease, FDG-PET seems to be highly sensitive.

Computed tomography diagnosis of macroscopic pulmonary fat embolism.

Pulmonary fat embolism probably occurs commonly after major orthopedic injuries and after orthopedic surgery. Furthermore, tiny fat emboli can often be shown by transesophageal echocardiography during orthopedic surgery. However, large macroscopic are rarely identified radiologically. Macroscopic fat emboli have been previously described in the common femoral vein and inferior vena cava on abdominal imaging. To the authors' knowledge, a macroscopic fat embolus in the pulmonary arteries has not been previously described. The authors report a case of a woman who, on computed tomography, had a large fat embolus after intramedullary rod placement for an isolated left femur fracture.