Detection of the detachment of immobilized contrast agent in medical imaging applications

Abstract

An embodiment of a solution is proposed for imaging a body-part that is perfused with a contrast agent. A corresponding method includes the step of providing a sequence of input images (for example, acquired with an ultrasound scanner); the input images offer a digital representation over time of the body-part. Each input image includes a plurality of input values (i.e., pixel or voxel values); each input value is indicative of a response to an interrogation signal (such as an echo signal for ultrasound waves) of a corresponding location of the body-part, which possibly includes the contrast agent. The method further includes the step of generating at least one filtered image from a plurality of selected ones of the input images (such as all of them or a subset thereof). Each filtered image includes a filtered value for each of a plurality of selected ones of the locations (for example, in a region of interest, or ROI). The filtered value of each selected location is indicative of the contrast agent that leaves the selected location after being substantially stationary at the selected location for a period of time, which is comprised between a first non-zero threshold and a second threshold higher than the first threshold (such as because the contrast agent detaches from the location after having been immobilized thereon, or because it was moving very slowly). The filtered value is obtained by reducing, where present, a contribution of the contrast agent that is substantially stationary at the selected location along the selected input images for a period of time equal to or shorter than the first threshold, and by reducing a contribution of the contrast agent that is substantially stationary at the selected location along the selected input images for a period of time equal to or longer than the second threshold.

Description

technical field [0001] The invention relates to the field of medical imaging. More specifically, the present invention relates to contrast agent imaging applications. Background technique [0002] Medical imaging is a well-established technology (in the field of medically applied devices) that enables the analysis of body parts of a patient in a substantially non-invasive manner. One specific medical imaging technique is based on the recording of echo signals produced by applying ultrasound waves to body parts. This technique can advantageously be accomplished by administering to the patient an ultrasound contrast agent (UCA, for example composed of a phospholipid-stabilized suspension of gas-filled microbubbles); Visualization of the vascular system. [0003] Target-specific contrast agents adapted to reach specific (biological) targets and remain immobilized thereon have also been proposed in recent years to facilitate the detection of specific pathologies. In particul...

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Problems solved by technology

However, such transiently immobilized contrast agents are completely indistinguishable from permanently immobilized contrast agents when they attach to passive targets

Therefore, if the body part is analyzed shortly after administration of the target-specific contrast agent to the patient, any temporarily immobilized contrast agent will lead to misidentification and localization of the desired target (false positive)

[0009] Furthermore, the above solutions also fail to differentiate persistently immobilized contrast agents from very slowly moving circulating contrast agents (e.g. at the microvascular level)

In particular, when a slow-moving contrast agent remains around the same location longer than the filter window of the modified Min_IP algorithm, it appears stationary at those moments; The intensity peak of the echo signal is too wide to be removed by the modified Min_IP algorithm

[0010] All of the above issues can adversely affect the spatial delineation and quantification of persistently immobilized contrast agents, preventing proper detection of the pathology of interest

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