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. 2017 Jun;30(3):358-368.
doi: 10.1007/s10278-017-9941-1.

Clinical Applications of a CT Window Blending Algorithm: RADIO (Relative Attenuation-Dependent Image Overlay)

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Free PMC article

Clinical Applications of a CT Window Blending Algorithm: RADIO (Relative Attenuation-Dependent Image Overlay)

Jacob C Mandell et al. J Digit Imaging. .
Free PMC article

Abstract

A methodology is described using Adobe Photoshop and Adobe Extendscript to process DICOM images with a Relative Attenuation-Dependent Image Overlay (RADIO) algorithm to visualize the full dynamic range of CT in one view, without requiring a change in window and level settings. The potential clinical uses for such an algorithm are described in a pictorial overview, including applications in emergency radiology, oncologic imaging, and nuclear medicine and molecular imaging.

Keywords: CT dynamic range; CT window settings; Contrast sensitivity; Grayscale visualization.

Conflict of interest statement

Les R. Folio is an associate investigator in a research agreement with Carestream Health (Rochester, NY).

Figures

Fig. 1
Fig. 1
Diagram demonstrating the concept of the RADIO window blending algorithm, which blends the regions of an image that are not overlapping in attenuation
Fig. 2
Fig. 2
Diagram demonstrating the RADIO window blending algorithm. The three conventional CT window settings in soft tissue, bone, and lung windows are placed on separate layers in a Photoshop document. The soft tissue window layer is not modified. On the bone window layer, only relatively high attenuation information is retained, which replaces the corresponding pixel locations in the soft tissue window. On the lung window layer, only relatively low attenuation is maintained, which is summed with the underlying soft tissue window
Fig. 3
Fig. 3
Screenshot from Adobe Photoshop demonstrating the advanced blending settings for the lung window layer (left image) and the bone window layer (right image)
Fig. 4
Fig. 4
a Axial contrast-enhanced CT of a normal chest demonstrating the RADIO window blended algorithm. Key features to note include relative good visualization of the osseous structures, the lungs, and the soft tissues. b Conventional soft tissue, c bone, and d lung window settings comprising the blended image
Fig. 5
Fig. 5
a Axial noncontrast CT of the cervical spine at the level of C2 with the RADIO window blending algorithm applied, using soft tissue and bone source images. There are fractures of C2 involving the left pedicle and right facet (white arrows). There is a subtle epidural hematoma (black arrows point to the interface of the hematoma and the CSF), causing spinal stenosis. b Conventional soft tissue and c bone window settings comprising the blended image
Fig. 6
Fig. 6
a Axial contrast-enhanced CT of the chest in a trauma patient with RADIO window blending algorithm applied, using soft tissue, bone, and lung source images. There is a small left anterior pneumothorax (white arrow), and a subtle nondisplaced fracture of a left posterior rib (black arrow). b Conventional soft tissue, c bone, and d lung window settings comprising the blended image
Fig. 7
Fig. 7
a Axial noncontrast CT of the head with RADIO window blending applied, using brain and bone windows. There is a large right epidural hematoma (white arrows) and subtle overlying temporal bone fractures (gray arrows). b Conventional brain and c bone window settings comprising the blended image
Fig. 8
Fig. 8
a Axial contrast-enhanced CT of the chest in a patient with lung cancer with RADIO window blending algorithm applied, using soft tissue, bone, and lung source images. There are enlarged right hilar lymph nodes (white arrows), causing narrowing of the right bronchus intermedius (black arrow) and mild post-obstructive atelectasis (gray arrow). b Conventional soft tissue, c bone, and d lung window settings comprising the blended image
Fig. 9
Fig. 9
a Axial contrast-enhanced CT of the chest in a patient with a soft tissue sarcoma with RADIO window blending algorithm applied, using soft tissue, bone, and lung source images. There is a left lower lobe mass (arrow), which is closely associated with a pulmonary vessel. b Conventional soft tissue, c bone, and d lung window settings comprising the blended image
Fig. 10
Fig. 10
a Axial fused PET-CT image in a patient with lung cancer with RADIO window blending algorithm applied, using soft tissue, bone, lung, and PET source images. There is an FDG-avid right hilar mass and bilateral FDG-avid hilar lymph nodes. b Conventional soft tissue, c bone, and d lung window settings comprising the blended image
Fig. 11
Fig. 11
a Axial fused PET-CT image with RADIO window blending algorithm applied, using soft tissue, bone, lung, and PET source images. There is an FDG-avid pleural-based mass-like opacity in the superior segment of the right lower lobe (arrow), representing metastatic disease in a patient with squamous cell carcinoma of the mouth treated previously with radiation and chemotherapy. b Conventional soft tissue, c bone, and d lung window settings comprising the blended image

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