Malignant pleural effusion (MPE) is a sign of advanced cancer and is associated with significant symptom burden and mortality. To date, management has been palliative in nature with a focus on draining the pleural space, with therapies aimed at preventing recurrence or providing intermittent drainage through indwelling catheters. Given that patients with MPEs are heterogeneous with respect to their cancer type and response to systemic therapy, functional status, and pleural milieu, response to MPE therapy is also heterogeneous and difficult to predict. Furthermore, the impact of therapies on important patient outcomes has only recently been evaluated consistently in clinical trials and cohort studies. In this review, we examine patient outcomes that have been studied to date, address the question of which are most important for managing patients, and review the literature related to the expected value for money (cost-effectiveness) of indwelling pleural catheters relative to traditionally recommended approaches.

A method is proposed to determine the cone-beam x-ray acquisition geometry of an imaging system using a phantom consisting of discrete x-ray opaque markers defining two parallel rings sharing a common axis. The phantom generates an image of two ellipses which are fitted to an ellipse model. A phantom-centric coordinate system is used to simplify the equations describing the ellipse coefficients such that a solution describing the acquisition geometry can be obtained via numerical optimization of only three of the nine unknown variables. We perform simulations to show how errors in the fit of the ellipse coefficients affect estimates of the acquisition geometries. These simulations show that for ellipse projections sampled with 1200 markers, 25 microm errors in marker positions and a source-detector distance (SDD) of 1.6 m, we can measure angles describing detector rotation with a mean error of <0.002 degrees and a standard deviation (SD) of <0.03 degrees. The SDD has a mean error of 0.004 mm and SD = 0.24 mm. The largest error is associated with the determination of the point on the detector closest to the x-ray source (mean error = 0.05 mm, SD = 0.85 mm). A prototype phantom was built and results from x-ray experiments are presented.

Inhaled molecular oxygen has been widely used in humans to evaluate pulmonary ventilation using MRI. MR imaging has recently played a greater role in examining the morphologic and physiologic characteristics of mouse models of lung disease where structural changes are highly correlated to abnormalities in respiratory function. The motivation of this work is to develop oxygen-enhanced MR imaging for mice. Conventional human MR techniques cannot be directly applied to mouse imaging due to smaller dimensions and faster cardiac and respiratory physiology. This study examines the development of oxygenenhanced MR as a noninvasive tool to assess regional ventilation in spontaneously breathing mice. An optimized cardiactriggered, respiratory-gated fast spin-echo imaging sequence was developed to address demands of attaining adequate signal from the parenchyma, maintaining practical acquisition times, and compensating for rapid physiological motion. On average, a 20% T 1 -shortening effect was observed in mice breathing 100% oxygen as compared to air. The effect of ventilation was shown as a significant signal intensity increase of 11% to 16% in the mouse parenchyma with 100% oxygen inhalation. This work demonstrates that adequate contrast and resolution can be achieved using oxygen-enhanced MR to visualize ventilation, providing an effective technique to study ventilation defects in mice. Key words: lung MRI; mouse; ventilation; oxygen-enhancedOxygen-enhanced MR imaging is a novel technique used to assess regional ventilation of the lung using inhaled molecular oxygen as a contrast agent (1). Molecular oxygen is weakly paramagnetic, and the effect of ventilation is visualized by signal intensity increase in MR images of the lung parenchyma acquired with subjects breathing 100% oxygen as compared to room air. During gas exchange, oxygen diffuses across the alveolar membrane and into the pulmonary capillary blood, coupling with hemoglobin to form oxyhemoglobin as well as dissolving into blood plasma as molecular oxygen (2). The latter contributes to a reduction in the longitudinal relaxation time of surrounding protons in the pulmonary blood that can be detected by T 1 -weighted MR imaging as regions of increased signal intensity. The T 1 -shortening effect is mainly attributed to the excess molecular oxygen because the concentration dissolved in the blood is raised by three-to fivefold with 100% oxygen inhalation, an increase much greater than for the amount of oxygen bound to hemoglobin when breathing 100% oxygen (2,3). Hence, oxygen-enhanced MR provides functional information about the combined ventilation, oxygen diffusion, and perfusion physiology of the lung.Proton MR imaging of the lung, including oxygen-enhanced MR, is challenged by the unique morphology and physiology of the lung. The low proton density of the inflated lung tissue, multiple air-tissue interfaces of the alveoli, and movement of the chest all result in poor image quality due to reduced MR signal, large magnetic susceptibility gradients, and respir...