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ObjectiveTo assess the diagnostic accuracy of peripheral capillary oxygen saturation (SpO2) while breathing room air for 5 min (the ‘Air-Test’) in detecting postoperative atelectasis.DesignProspective cohort study. Diagnostic accuracy was assessed by measuring the agreement between the index test and the reference standard CT scan images.SettingPostanaesthetic care unit in a tertiary hospital in Spain.ParticipantsThree hundred and fifty patients from 12 January to 7 February 2015; 170 patients scheduled for surgery under general anaesthesia who were admitted into the postsurgical unit were included.InterventionThe Air-Test was performed in conscious extubated patients after a 30 min stabilisation period during which they received supplemental oxygen therapy via a venturi mask. The Air-Test was defined as positive when SpO2 was ≤96% and negative when SpO2 was ≥97%. Arterial blood gases were measured in all patients at the end of the Air-Test. In the subsequent 25 min, the presence of atelectasis was evaluated by performing a CT scan in 59 randomly selected patients.Main outcome measuresThe primary study outcome was assessment of the accuracy of the Air-Test for detecting postoperative atelectasis compared with the reference standard. The secondary outcome was the incidence of positive Air-Test results.ResultsThe Air-Test diagnosed postoperative atelectasis with an area under the receiver operating characteristic curve of 0.90 (95% CI 0.82 to 0.98) with a sensitivity of 82.6% and a specificity of 87.8%. The presence of atelectasis was confirmed by CT scans in all patients (30/30) with positive and in 5 patients (17%) with negative Air-Test results. Based on the Air-Test, postoperative atelectasis was present in 36% of the patients (62 out of 170).ConclusionThe Air-Test may represent an accurate, simple, inexpensive and non-invasive method for diagnosing postoperative atelectasis.Trial RegistrationNCT02650037.

Osteoid osteoma (OO) is a benign skeletal neoplasm. Twenty-eight patients with proven OO were studied with MRI regarding soft tissue involvement which was diagnosed when high proton-density and T2-weighted signal intensity and low signal intensity on T1-weighted images were found close to bone. Most tumors were located in the femur and tibia; 6 cases diaphyseal, 12 metaphyso-diaphyseal, and 10 epiphyseal. In relation to the cortex, 15 were located centrally or in its outer margin. Soft tissue involvement was found in 15 patients (53.6 %). A statistical relationship was found between soft tissue involvement and the tumor's location with regard to the cortex, being more frequent in peripherally located tumors. Therefore, soft tissue involvement is a frequent finding in peripherally located OO.

The prevalence of Baker cysts in MR studies of the knee is high. Its presence and volume are related to the quantity of synovial fluid, and to the presence and severity of meniscal lesions.

The aim of this case report is to describe the appearance on magnetic resonance imaging (MRI) of an incidentally found adenomatoid tumor of the adrenal gland, and to evaluate the utility of MRI in characterizing this type of tumor. The appearance of the tumor was nonspecific on T1-weighted in-phase, opposed-phase, and T2-weighted images, as well as its behavior after paramagnetic contrast administration, outlining the differential diagnosis among carcinoma, metastatic tumors, and pheochromocytoma. After surgery, the pathologic diagnosis was adenomatoid benign tumor of mesothelial origin. Although MRI enables the characterization of most benign lesions of the adrenal gland, the appearance of other lesions is nonspecific. In our case, MRI did not assist in preoperative diagnosis, guiding us towards a diagnosis of malignancy.