Browse Prior Art Database

Publication Date: 2005-Aug-05
Document File: 5 page(s) / 26K

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The Prior Art Database


In an embodiment, the user prescribes a MULTISTATION series. The mask images from all the stations are obtained. The mask images are used to get the size of the stitched image and the size of the image view port. As the images from Station1 are reconstructed, they are subtracted from the mask and the subtracted image is stitched with the mask image from station2. This image is displayed in the new image view port. All subsequent stitched images replace the previous image. Figure 4 shows how the combined image appears in the view port. Once all the images in Station1 are reconstructed, the Station2 scanning starts. The first image from staion2 is subtracted from the mask obtained previously from Station2. This subtracted image is stitched with the last image from station1 and displayed in the view port. As subsequent images from Station2 are reconstructed, their subtracted image are stitched with the last image from station1 and displayed in the view port.

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MR provides a way of doing Vascular studies to track contrast flow. Contrast Enhanced Magnetic Resonance Angiography (CE MRA) is a technique for obtaining images of the vascular structures.  For this, a contrast agent is introduced into the vascular system of the patient to be examined. The magnetic resonance (MR) signals originating from the contents of the blood vessels are acquired following the injection of the contrast agent. MR signals acquired are notably of higher intensity once the contrast agent has entered the blood. An arterial magnetic resonance image, which shows the arteries getting filled with the contrast agent, is derived from such MR signals. After some time, when the contrast agent has also reached the veins and has not yet disappeared from the arteries, MR signals are acquired again. A venous magnetic resonance image which shows only the veins filled with the contrast agent is derived from the latter MR signals, by subtracting the arterial images from it. This removes the stationary parts and the location through which the contrast is flowing is brought out.

Typically this is done on multiple stations (multiple locations), to track the contrast flow. 

Typically, the image of the location, before the contrast is injected, is scanned. This is called as the mask. Subsequent images taken after the contrast is injected are subtracted from the mask.

Only a part of the vasculature can be imaged in the first station and these images appear in the first series. The remaining vasculature from the second station appears in the second series. Typically for lower body studies, we require the whole lower body to be viewed at a shot so that the flow of contrast through the multiple stations can be observed as it flows through the vasculature. Because of the restriction of the FOV we have to do a multi-station scan that covers overlapping regions of the locations to be imaged. It is not possible to view the whole area completely. The images have to be viewed offline per station basis. This does not give a correct view of the contrast flow. The images have to be placed side-by-side or artificially joined by hand offline to get a better view.

Figure1 shows the image taken from station1 and figure2 shows the image taken from station2. Most of the times the user has to place the figure1 on top of figure2 and then view the image. This has to be done manually or has to be done offline and most of the times the overlap might not be correct which might mislead in giving diagnoses. Figure3 shows how the image should actually appear. An image stitching software, stitches the images after the images have been obtained. There is no way of viewing the subtracted images from multiple stations as a single piece.

Also, the user has to scroll through the series to view the contrast flow. This has to be repeated for both the stations.