Variability of semiautomated lung nodule volumetry on ultralow-dose CT: comparison with nodule volumetry on standard-dose CT.

The study investigates the effect of a substantial dose reduction on the variability of lung nodule volume measurements by assessing and comparing nodule volumes using a dedicated semiautomated segmentation software on ultralow-dose computed tomography (ULD-CT) and standard-dose computed tomography (SD-CT) data. In 20 patients, thin-slice chest CT datasets (1 mm slice thickness; 20% reconstruction overlap) were acquired at ultralow-dose (120 kV, 5 mAs) and at standard-dose (120 kV, 75 mAs), respectively, and analyzed using the segmentation software OncoTREAT (MeVis, Bremen, Germany; version 1.3). Interobserver variability of volume measurements of 202 solid pulmonary nodules (mean diameter 11 mm, range 3.2-44.5 mm) was calculated for SD-CT and ULD-CT. With respect to interobserver variability, the 95% confidence interval for the relative differences in nodule volume in the intrascan analysis was measured with -9.7% to 8.3% (mean difference -0.7%) for SD-CT and with -12.6% to 12.4% (mean difference -0.2%) for ULD-CT. In the interscan analysis, the 95% confidence intervals for the differences in nodule volume ranged with -25.1% to -23.4% and 26.2% to 28.9% (mean difference 1.4% to 2.1%) dependent on the combination of readers and scans. Intrascan interobserver variability of volume measurements was comparable for ULD-CT and SD-CT data. The calculated variability of volume measurements in the interscan analysis was similar to the data reported in the literature for CT data acquired with equal radiation dose. Thus, the evaluated segmentation software provides nodule volumetry that appears to be independent of the dose level with which the CT source dataset is acquired.

Initial experience with a chest pain protocol using 320-slice volume MDCT.

We sought to determine the feasibility and image quality of 320-slice volume computed tomography (CT) angiography for the evaluation of patients with acute chest pain. Thirty consecutive patients (11 female, 19 male, mean age 63.2 +/- 14.2 years) with noncritical, acute chest pain underwent 320-slice CT using a protocol consisting of a nonspiral, nongated CT of the entire chest, followed by a nonspiral, electrocardiography-gated CT study of the heart. Data were acquired following a biphasic intravenous injection of 90 ml iodinated contrast agent. Vessel attenuation values of different thoracic vascular territories were recorded, and image quality scored on a five-point scale by two readers. Mean attenuation was 467 +/- 69 HU in the ascending aorta, 334 +/- 52 HU in the aortic arch, 455 +/- 71 HU in the descending aorta, 492 +/- 94 HU in the pulmonary trunk, and 416 +/- 63 HU and 436 +/- 62 HU in the right and left coronary artery, respectively. Radiation exposure estimates ranged between 7 and 14 mSv. The CT protocol investigated enabled imaging of the thoracic aorta, coronary and pulmonary arteries with an excellent diagnostic quality for chest pain triage in all patients. This result was achieved with less contrast material and reduced radiation exposure compared with previously investigated imaging protocols.

Computer-aided detection in computed tomography colonography with full fecal tagging: comparison of standalone performance of 3 automated polyp detection systems.

PURPOSE: We sought to compare the performance of 3 computer-aided detection (CAD) polyp algorithms in computed tomography colonography (CTC) with fecal tagging. METHODS: CTC data sets of 33 patients were retrospectively analysed by 3 different CAD systems: system 1, MedicSight; system 2, Colon CAD; and system 3, Polyp Enhanced View. The polyp database comprised 53 lesions, including 6 cases of colorectal cancer, and was established by consensus reading and comparison with colonoscopy. Lesions ranged from 6-40 mm, with 25 lesions larger than 10 mm in size. Detection and false-positive (FP) rates were calculated. RESULTS: CAD systems 1 and 2 could be set to have varying sensitivities with higher FP rates for higher sensitivity levels. Sensitivities for system 1 ranged from 73%-94% for all lesions (78%-100% for lesions > or =10 mm) and, for system 2, from 64%-94% (78%-100% for lesions > or =10 mm). System 3 reached an overall sensitivity of 76% (100% for lesions > or =10 mm). The mean FP rate per patient ranged from 8-32 for system 1, from 1-8 for system 2, and was 5 for system 3. At the highest sensitivity level for all polyps (94%), system 2 showed a statistically significant lower FP rate compared with system 1 (P = .001). When analysing lesions > or =10 mm, system 3 had significantly fewer FPs than systems 1 and 2 (P < .012). CONCLUSIONS: Standalone CTC-CAD analysis in the selected patient collective showed the 3 systems tested to have a variable but overall promising performance with respect to sensitivity and the FP rate.

Intra- and interobserver variability of linear and volumetric measurements of brain metastases using contrast-enhanced magnetic resonance imaging.

OBJECTIVES: To compare the intra- and interobserver variability of diameter and semiautomated volume measurements of brain metastases on contrast-enhanced magnetic resonance imaging (CE-MRI) data. MATERIALS AND METHODS: About 75 MRI staging examinations of patients with metastasized renal cell carcinoma, thyroid cancer, or malignant melanoma (mean age, 56 years; range, 40-75 years) were included. Patients had been examined with a routine MRI protocol, including a CE 3D T1-weighted MP-RAGE sequence (1-mm slice thickness). MRI data were retrospectively analyzed using the OncoTREAT segmentation system (MeVis, Bremen, Germany, version 1.6). Volume of 355 enhancing brain metastases included in the analysis as well as the largest diameter according to Response Evaluation Criteria for Solid Tumors were measured by 2 radiologists. Intra- and interobserver variability was calculated. RESULTS: Metastases (n = 355) had a mean diameter of 12.2 mm (range, 3.4-44.3 mm) and a mean volume of 1.4 cm(3) (range, 12-25.1 cm(3)). With respect to interobserver variability analysis revealed broader limits of agreement for response evaluation criteria for solid tumor measurements of all lesions (range, +/-27.8%-+/-33.0%; unsigned mean: 0.2%-2.5%) than for volume measurements (range, +/-21.4%-+/-23.3%; unsigned mean, 0.1%-0.3%) with statistically significant differences between diameter and volume measurements (P