Seminars in respiratory and critical care medicine
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Semin Respir Crit Care Med · Feb 2014
ReviewImaging assessment of lung tumor angiogenesis: insights and innovations.
Lung cancer is the leading cause of cancer death in the United States. It is estimated that more than 228,000 new cases will be diagnosed in 2013, accounting for approximately 159,000 or 27% of all cancer deaths. Survival in these patients remains poor despite advances in surgery, definitive radiotherapy, and chemotherapy for primary and metastatic non-small cell lung cancer. ⋯ Hypoxia and angiogenesis play an important role in the development and progression of lung cancer. Targeted and non-targeted imaging techniques in the preclinical and clinical setting, combined with advanced postprocessing techniques to assess tumor heterogeneity, may enable clinicians to better characterize lung tumors, and to predict and assess response to treatment. In this review, we summarize our current understanding of angiogenesis in lung cancer and discuss the available imaging techniques to assess this in the preclinical and clinical setting.
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This article reviews the current diagnostic strategies for patients with suspected pulmonary embolism (PE) focusing on the current first choice imaging modality, computed tomographic pulmonary angiography (CTPA). Diagnostic strengths and weaknesses and associated cost-effectiveness of the diagnostic pathways will be discussed. The radiation dose risk of these pathways will be described and techniques to minimize dose will be reviewed. ⋯ Although current cost-effectiveness evaluations have established CT as integral in the PE diagnostic pathway, failure to acknowledge the impact of alternate diagnosis represents a current knowledge gap. The emerging dual energy capacity of current CT scanners offers the potential to evaluate both pulmonary vascular morphology and ventilation perfusion relationships within the lung parenchyma at high spatial resolution. This dual assessment of lung morphology and lung function at low (< 5 millisievert) radiation dose represents a substantial advance in PE imaging.
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Semin Respir Crit Care Med · Feb 2014
ReviewPET-CT: Current Applications and New Developments in the Thorax.
Positron emission tomography computed tomography(PET-CT) imaging has emerged as an essential clinical diagnostic tool in the evaluation of thoracic abnormalities. Currently, its primary role is for tumor imaging; it helps to differentiate benign from malignant nodules, stage tumors, determine response, and follow patients after therapy is complete. It has also been used for nononcologic diseases, but the indications are less well defined. PET is a fundamental component of the molecular imaging initiative, and as new more specific imaging probes and better instrumentation are developed, PET-CT is certain to improve diagnostic accuracy and become even more integrated into the imaging armamentarium.
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Beyond being a substitute for X-ray, computed tomography, and scintigraphy, magnetic resonance imaging (MRI) inherently combines morphologic and functional information more than any other technology. Lung perfusion: The most established method is first-pass contrast-enhanced imaging with bolus injection of gadolinium chelates and time-resolved gradient-echo (GRE) sequences covering the whole lung (1 volume/s). Images are evaluated visually or semiquantitatively, while absolute quantification remains challenging due to the nonlinear relation of T1-shortening and contrast material concentration. ⋯ Respiratory mechanics: Time-resolved series with high background signal such as GRE or steady-state free precession visualize the movement of chest wall, diaphragm, mediastinum, lung tissue, tracheal wall, and tumor. The assessment of volume changes allows drawing conclusions on regional ventilation. With this arsenal of functional imaging capabilities at high spatial and temporal resolution but without radiation burden, MRI will find its role in regional functional lung analysis and will therefore overcome the sensitivity of global lung function analysis for repeated short-term treatment monitoring.
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Semin Respir Crit Care Med · Feb 2014
Risks, Benefits, and Risk Reduction Strategies in Thoracic CT Imaging.
Chest computed tomography (CT) is a useful tool for diagnosing various thoracic conditions and has become the diagnostic imaging modality of choice for many diseases. Recent discussions about the radiation dose from CT have attracted the attention of medical professionals and the general public. ⋯ Four techniques are discussed in detail, including tube current modulation, automatic exposure control, automatic tube voltage selection, and iterative image reconstruction. Adopting these techniques in routine clinical practice can dramatically reduce radiation dose levels.