Effect of slab thickness on the CT detection of pulmonary nodules: use of sliding thin-slab maximum intensity projection and volume rendering.

OBJECTIVE: The objective of this study was to evaluate the detection rates of pulmonary nodules on CT as a function of slab thickness using sliding thin-slab maximum intensity projection (MIP) and volume rendering (VR). SUBJECTS AND METHODS: Eighty-eight oncology patients (33 women, 55 men; mean age, 59 years; age range, 18-81 years) who routinely underwent chest CT examinations were prospectively included. Two radiologists independently evaluated each CT examination for the presence of pulmonary nodules using MIP and VR, with each image reconstructed using three different slab thicknesses (5, 8, 11 mm). The standard of reference was the maximum number of detected nodules, which were classified by localization and size, judged to be true-positives by a consensus panel. Interreader agreement was assessed by kappa value on a nodule-by-nodule basis. Sensitivities for both reconstruction techniques and for the three slab thicknesses were calculated using the proportion procedure for survey data with the patient as the primary sample unit and were compared using the Wilcoxon's signed rank test with Bonferroni correction for both readers separately. RESULTS: One thousand fifty-eight true-positive nodules were detected. Interreader agreement was fair to moderate. Sensitivity for pulmonary nodules was superior for 8-mm MIP (reader 1, 84%; reader 2, 81%) and was significantly better than the sensitivities of all other tested techniques for both readers (p < 0.001 each) independent of nodule localization and size (except for one reader's analysis of 8-mm MIP versus 11-mm MIP for nodules > 8 mm). A higher sensitivity was achieved using MIP than VR. CONCLUSION: MIP with a slab thickness of 8 mm is superior in the detection of pulmonary nodules to all other tested techniques.

Swiss teleradiology survey: present situation and future trends.

The purpose of this study was to obtain a survey about the present situation including the usage pattern, technical characteristics and the anticipated future of teleradiology in Switzerland. An internet-based questionnaire was made available to all members of the Swiss Society of Radiology. Questions concerning current teleradiology usage, the type of transmitted modalities, the technology employed, security, billing issues and the anticipated future of teleradiology were addressed. One hundred and two (22.67%) of 450 radiologists responded to the survey. Of the total, 41.2% (42) were teleradiology users, 35.3% (36) planned to use teleradiology in the near future and 24.5% (25) did not use or plan to use teleradiology. The mean number of examinations transmitted per month was 198 (range 1-2,000) and the mean distance was 33 km (range 1,250 km). An emergency service was considered the most important purpose (mean score 6.90; minimum 1, maximum 10) for the use of teleradiology, followed by image distribution (mean 6.74) and expert consultation (mean 6.61). The most commonly transmitted modality was computed tomography (mean 8.80), followed by conventional X-rays (8.40) and magnetic resonance imaging (8.32). The most commonly transmitted format was Digital Imaging and Communications in Medicine (DICOM) (66.7%), followed by bitmap/Joint Photographic Experts Group (jpg) (38.1%), using the DICOM send/receive protocol (52.4%), followed by the hypertext transfer protocol (26.2%) and e-mail (21.4%). For security a secure connection (54.8%) followed by encryption (14.3%) and anonymization (9.5%) was used. For the future, image distribution was rated the most important aspect of teleradiology (7.88), followed by emergency (7.22) and expert consultation (6.53). Development of legal regulations is considered most important (8.17), followed by data security guidelines (8.15). Most radiologists believe that insurance companies should pay for the costs of teleradiology (37.3%), followed by the radiologist (33.3%). In conclusion, in Switzerland a wide spectrum of teleradiology applications and technologies is in use. Guidelines and reimbursement issues remain to be solved.