Farbkodierte Darstellung des Lungenparenchyms bei vermuteter Lungenembolie mittels Mehrschicht-Spiral-CT

Abstract

Summary. Purpose: The purpose of our preliminary study was to evaluate the feasibility of a new technique for the perfusion weighted color display of the density of lung parenchyma derived from multi-slice CT (MSCT) data sets of clinical routine examinations for visualization of pulmonary embolism (PE). Materials and Methods: Imaging of patients with suspected PE was performed on a commercially available MSCT (Somatom Volume Zoom; Siemens, Forchheim, Germany) after intravenous application of 120 cc of contrast-medium using a power injector. Scan parameters were 140 kV and 100 mAs, using a thin collimation of 4 1 mm and a table speed of 7 mm (pitch: 1.75). Derived from thin collimation axial slices (slice thickness eff. 1.25 mm, reconstruction increment 0.8 mm), a new image processing technique was deployed. Based on these source images, an automated 3D-segmentation of the lungs was performed followed by threshold based extraction of major airways and vascular structures. The filtered volume data were color encoded and finally overlayed onto the original CT images. This color encoded display of parenchymal density distribution of the lungs was shown in axial, coronal and sagittal plane orientation. In four patients with excluded PE as well as in two patients with proven PE this new technique was performed. Results: In the four patients that were considered negative regarding PE on MSCT, lung densitometry showed a homogeneous distribution of color encoded densities without circumscribed decreased or increased areas, beside the usually present gravity-dependent gradient in ventro-dorsal direction. In the two patients with proven PE, low density values on perfusion weighted color maps were found distally to the occluded pulmonary arteries. Conclusions: Our initial experience indicates that lung densitometry with an optimized display of the density distribution within the lung parenchyma may provide additional information in patients with suspected or proven PE. However, a comparison with ventilation/perfusion scintigraphy and a larger number of patients are necessary for the full clinical evaluation of this new functional imaging methodology.

Dual-Energy CT Angiography of the Lung in Patients with Suspected Pulmonary Embolism: Initial Results

“…Previous studies have evaluated CT for the assessment of lung perfusion in patients with suspected pulmonary embolism. In a study by Wildberger et al, perfusion weighted maps were generated by color-coding the density of lung parenchyma in contrast-enhanced CTA [6]. Schoepf et al evaluated a dynamic multisection EBCT protocol for pulmonary perfusion imaging [7].…”

“…The idea of lung perfusion imaging by CT in PE is not new. In a previous study by Wildberger et al, density differences of the perfused and non-perfused lung on lung CTA data were highlighted by spectral color coding [6]. The main disadvantage of this approach is that differences in the density of lung parenchyma may also be caused by emphysema, air-trapping, and ground-glass opacities.…”

Assessing lung function using contrast‐enhanced dual‐energy computed tomography for potential applications in radiation therapy

“…Nevertheless, higher CT numbers could still inform on the level of functionality of an area due to an increased amount of contrast agent. In that regards, Wildberger et al have shown how perfused map based on the intensity of CT numbers could help detect pulmonary embolism. By combining this idea with the same thresholding step described in the DECT method, the functional level is directly retrieved from the CT number of the voxels inside the functional area of the CT mixed images.…”

“…16,17 The DECT approach was also successful to detect perfusion defects in the context of pulmonary embolism [18][19][20][21][22] and parenchymal lung disease. 23,24 Other single-energy CT (SECT) techniques may also process contrast-enhanced CT images to produce functional maps of the lung parenchyma; 6,25,26 however, they do not quantitatively address the perfused blood volume.…”

Reformatierungen als Lösungsansatz für die Problematik der unterschiedlichen Schichtführung beim Vergleich von3He-MRT und HR-CT der Lunge

“…Hierzu erschienen Computer-generierte Rekonstruktionen im Sinne einer multiplanaren Reformatierung (MPR) in der jeweils entsprechenden Orientierung hilfreich und einfach durchführbar [9,10]. Ziel dieser Mitteilung ist es, die Hilfestellung von multiplanaren Reformatierungen von 3 He-MRT und HR-CT beim Vergleich der beiden Verfahren anhand der Zuordnung anatomischer und pathologischer Strukturen zu prüfen.…”