Academic radiology
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Clinical Trial
Arterial spin labeling blood flow magnetic resonance imaging for the characterization of metastatic renal cell carcinoma(1).
This study sought to assess the feasibility of arterial spin labeling (ASL) blood flow (BF) magnetic resonance imaging (MRI) for the study of metastatic renal cell carcinoma (RCC) in the body, where the respiratory, cardiac, and peristaltic motions present challenges when applying ASL. ⋯ With background suppression, ASL MRI is a feasible method for quantifying BF in patients with renal cell carcinoma. This technique may be useful for evaluating tumor response to antiangiogenic agents.
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The purpose of this study was to evaluate the performance of a fully automated lung nodule detection method in a large database of low-dose computed tomography (CT) scans from a lung cancer screening program. Because nodules demonstrate a spectrum of radiologic appearances, the performance of the automated method was evaluated on the basis of nodule malignancy status, size, subtlety, and radiographic opacity. ⋯ We have evaluated an automated lung nodule detection method with a large number of low-dose CT scans from a lung cancer screening program. An overall sensitivity of 80% for malignant nodules was achieved with 0.85 false-positive detections per section. Such a computerized lung nodule detection method is expected to become an important part of CT-based lung cancer screening programs.
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The advantage of a higher static magnetic field for functional MRI has been advocated; however, the observed advantage varies. The aim of this study was to evaluate the effect of increasing static magnetic field strength on the task-related increase in blood oxygenation level-dependent (BOLD) signal and residual noise with visual stimuli of different frequencies, which may enable better comparisons of results of different MRI scanners. ⋯ There was a greater-than-linear increase in the contrast-to-noise ratio compared with the increase of field strength, demonstrating an advantage of using higher field strengths in fMRI studies.
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Comparative Study
Intraoperative tumor segmentation and volume measurement in MRI-guided glioma surgery for tumor resection rate control.
Gross-total surgery under intraoperative magnetic resonance imaging (MRI) is a promising method of glioma removal. The purpose of this article is intraoperative measurement of resected tumor volume in MRI-guided glioma surgery using semiautomatic image segmentation to unbiased resection rate control. ⋯ The FC-based tumor segmentation method can be used for intraoperative tumor segmentation and volume measurement in MRI-guided glioma surgery using 0.3-T open magnets. This method is useful for objective resection rate monitoring, which may ultimately minimize the amount of residual tumor in glioma surgery.
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The two-dimensional (2D)-three dimensional (3D) registration of a computed tomography image to one or more x-ray projection images has a number of image-guided therapy applications. In general, fiducial marker-based methods are fast, accurate, and robust, but marker implantation is not always possible, often is considered too invasive to be clinically acceptable, and entails risk. There also is the unresolved issue of whether it is acceptable to leave markers permanently implanted. Intensity-based registration methods do not require the use of markers and can be automated because such geometric features as points and surfaces do not need to be segmented from the images. However, for spine images, intensity-based methods are susceptible to local optima in the cost function and thus need initial transformations that are close to the correct transformation. ⋯ The use of one fiducial marker reduces 2D-3D spine image registration error slightly and improves robustness substantially. The findings are potentially relevant for image-guided therapy. If one marker is sufficient to obtain clinically acceptable registration accuracy and robustness, as the preliminary results using the proposed hybrid similarity measure suggest, the marker can be placed on a spinous process, which could be accomplished without penetrating muscle or using fluoroscopic guidance, and such a marker could be removed relatively easily.