1. To learn about the creation of CT perfusion images.
2. To understand the complementarity between morphological and functional information.
3. To learn the various causes of perfusion defects.
Since the introduction of dual-energy CT (DECT) in clinical practice, great interest has been directed toward analysis of the distribution of iodine in the most distal parts of the pulmonary circulation, often referred to as perfusion imaging. Initially only available with dual-source CT, dual-energy CT has become accessible to single-source CT, with the introduction of rapid kV switching and more recently, dual-layer (sandwich) detectors. Regardless of the difference in the technological approach, perfusion images are generated from the same data set as that used for morphological evaluation, offering the possibility of a simultaneous approach of structure and function in respiratory patients. This combined information provided with CT is a major advantage over scintigraphy and MRI, not only in the field of primary disorders of the pulmonary circulation, like acute pulmonary embolism, but also in the context of bronchopulmonary diseases where perfusion alterations can be interpreted with precise knowledge of the underlying morphologic changes. More recently, this complementarity has also been extended in the field of chronic thromboembolic disease and pulmonary hypertension while a growing interest is reported in oncologic indications. The purpose of this presentation is to make radiologists familiar with the use of CT lung perfusion in clinical practice.
1. To become familiar with the technical aspects of MRI perfusion.
2. To learn key imaging features.
3. To discuss the most relevant clinical indications.
Among functional lung magnetic resonance imaging (MRI) techniques, dynamic contrast-enhanced (4D) perfusion MRI is probably the most robust and widely used method that has entered the clinical arena of routine patient management. Because it delivers temporally resolved datasets, perfusion parameters such as time-to-peak or pulmonary blood flow may be directly quantified by dedicated post-processing. In pulmonary vascular disease it may help to identify arterio-venous-malformations, pulmonary shunts or anomalous venous return. In combination with contrast-enhanced and non-constrast enhanced lung MR angiography, 4D perfusion MRI is now considered an alternative for computed tomography angiography for pulmonary embolism. In case of airways disease such as cystic fibrosis or chronic obstructive pulmonary disease, 4D perfusion imaging exploits the physiological mechanism of hypoxic pulmonary vasoconstriction. This effects a downregulation of perfusion to functional lung units with reduced ventilation, i.e. airway obstruction. Thus, 4D perfusion MRI can directly visualize functional lung impairment associated with airways disease, even when small airways are affected that cannot be otherwise captured with structural imaging. The lecture will summarise technical aspects of performing 4D perfusion imaging with clinical MRI scanners, discuss the most important routine indications incl. implementation into routine workflow, and discuss most relevant imaging findings in vascular and airways disease. Further, future developments and non-contrast-dependent techniques will be reviewed.
1. To learn about the specificities of perfusion scintigraphy.
2. To understand the advantages of hybrid imaging.
3. To appreciate potential pitfalls of nuclear medicine techniques.
Initial management of pulmonary vascular and lung diseases has consisted of lung scintigraphy, enabling the study of both lung perfusion and ventilation. The advent of CT and CTPA has replaced many of the acute indications. Nevertheless, there remains an important role for the use of both lung scintigraphy and the combined use of new hybrid systems (SPECT/CT) to study these disease and facilitate in their management. This presentation will evaluate the historical and current state-of-the-art capabilities of lung scintigraphy to study lung perfusion and ventilation. It will also evaluate the potential best applications in the current diagnostic management, as well as demonstrate some of the pitfalls of this technology.