Ultrasound system and method for forming an ultrasound image

The present invention is directed to an ultrasound system and a method for reformatting a planar image. The ultrasound system includes a volume data acquiring unit and an image processing unit. The volume data acquiring unit may acquire volume data by transmitting/receiving ultrasound signals to/from a target object of an un-echoic area. The image processing unit may perform inverse volume rendering upon the volume data to form a 3-dimensional image showing the target object and set a region of interest (ROI) on the target object in response to a user input. The image processor detects data corresponding to the ROI from the volume data and reformats the detected data to form a planar image.

The present application claims priority from Korean Patent Application No. 10-2007-0026909 filed on Mar. 20, 2007, the entire subject matter of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention generally relates to ultrasound systems, and more particularly to an ultrasound system and a method for displaying multi-planar images.

2. Background Art

The ultrasound system has become an important and popular diagnostic tool due to its non-invasive and non-destructive nature. Modern high-performance ultrasound imaging diagnostic systems and techniques are commonly used to produce two- or three-dimensional images of internal features of patients.

An ultrasound system generally uses a probe containing an array of piezoelectric elements to transmit and receive ultrasound signals. The ultrasound system forms an image of human internal tissues by electrically exciting transducer elements to generate ultrasound signals that travel into the body. Echoes reflected from tissues and organs return to the transducer element and are converted into electrical signals, which are amplified and processed to produce ultrasound data. The ultrasound data may include volume data obtained by using a 3-dimensional probe, etc.

Generally, the ultrasound system is configured to perform volume rendering upon the volume data to form a 3-dimensional ultrasound image. Also, the ultrasound system may be adapted to reformat planar images by using a reference plane (e.g., sagittal plane, coronal plane or axial plane) or an arbitrary plane set in the volume data, which is referred to as a multi-planar reformatting (MPR) method. The MPR method is widely used in various medical imaging fields in addition to the ultrasound fields.

However, the MPR method is carried out by reformatting the planar images with planes having merely different directions in the volume data in the conventional ultrasound system. Thus, it is difficult to obtain sufficient information regarding a target object to be reformatted to multi-planar images. As such, there is a problem in that the target object, which exists in many planes and has un-echoic areas (e.g., blood vessel), cannot be reformatted.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a block diagram showing an ultrasound system constructed in accordance with one embodiment of the present invention. Referring toFIG. 1, the ultrasound system100includes a Transmit/Receive (T/R) unit110, a beam former120, a volume data forming unit130, an image processing unit140, a storage unit150, an input unit160and a display unit170.

The T/R unit110may be operable to transmit ultrasound signals to a target object and receive ultrasound echo signals reflected from the target object to form reception signals. The T/R unit110may be a probe including a plurality of transducer elements for reciprocally converting ultrasound signals and electrical signals. The ultrasound signals transmitted from the T/R unit110may be propagated into the target object along an axial direction.

The beam former120may be operable to focus the reception signals by considering a distance between each transducer element and a focal point set in the target object and positions between the transducer elements.

The volume data forming unit130may be operable to form volume data based on the focused reception signals. The volume data may include position information corresponding to pixels (or voxels) of a 3-dimensional ultrasound image (i.e., coordinate information at a 3-dimensional coordinate system) and brightness information of the pixels (or voxels). The volume data formed in the volume data forming unit130may be stored in the storage unit150.

The image processing unit140may be operable to reformat a planar image based on the volume data. As illustrated inFIG. 2, the image processing unit140may include an inverse volume rendering unit141, a region of interest (ROI) setting unit142, a position detecting unit143and a planar reformatting unit144.

The inverse volume rendering unit141may be operable to perform inverse volume rendering upon the volume data by inverting gray levels of voxels contained in the volume data to thereby form a 3-dimensional reference image310containing the target object320of an un-echoic area, as shown inFIG. 3. The un-echoic area may be an area at which the ultrasound signals are not reflected, such as a blood vessel, pleural effusion, expansion of renal pelvis, hydrocephalic, urethra, duodenal atresia or the like.

From a user, the input unit160may receive setup information of ROI to be reformatted to the planar image from the 3-dimensional reference image. The setup information of ROI may include information of a start point and an end point of the ROI to be set on the target object of the un-echoic area in the 3-dimensional reference image310. The ROI setting unit142may be operable to set the ROI based on the setup information of ROI. The ROI setting unit142may set the start point411and the end point412on the target object320based on the setup information of the ROI. The ROI setting unit142may set a first shortest line421connecting the start point411to the end point412. The ROI setting unit142may detect a boundary point441along the first shortest line421from the start point411to the end point412. It may set a first straight line431connecting the start point411to the detected boundary point441. The boundary may be detected by using a change of brightness with a differential operator. In accordance with one embodiment of the present invention, the boundary may be detected by using an edge mask such as Sobel, Prewitt, Robert, Laplacian of Gaussian, Canny or the like. The ROI setting unit142may set a normal line451to the first straight line431at the boundary point441. The normal line451may have a predetermined length. The ROI setting unit142may compute brightness values of voxels within a predetermined range along the normal line451from the boundary point441and determine a direction having a relatively larger mean brightness value. The ROI setting unit142may set a second straight line432from the first boundary point441toward the determined direction at a predetermined angle with respect to the first straight line431. The ROI setting unit142may detect a boundary point442along the second straight line432and set a second shortest line422connecting the boundary point442to the end point412. The ROI setting unit142may repeatedly perform the above procedure until the straight line extending straight from the boundary point is connected to the end point412without passing the boundary point. The ROI setting unit142may set the ROI of a curvature line shape to be reformatted to the planar image by using curve fitting with the start point411, the end point412and a plurality of boundary points441-446.

The user input unit160may further receive an instruction for rotating the 3-dimensional reference image310. The instruction may include information upon a view point of the 3-dimensional reference image310. The image processing unit140may be operable to rotate the 3-dimensional image to be displayed at a different view point in response to the instruction while the ROI set on the target object. Thus, the user may easily check whether or not the ROI is appropriately set along the target object.

The position detecting unit143may be operable to detect positions of voxels corresponding to the set ROI on the target object in the 3-dimensional reference image310. The multi-planar reformatting unit144may be operable to detect data corresponding to the detected positions from the volume data, i.e., a gray level of brightness, and reformat the detected data to form planar image.

The storage unit150may be operable to store the volume data formed in the volume data forming unit130. The display unit170may be operable to display the 3-dimensional reference image and the reformatted planar image.

As described above, since the present invention forms a 3-dimensional image containing a target object of an un-echoic area through the inverse volume rendering method and set the ROI along the target object to thereby reformat the planar image, stricture or atresia of the blood vessel may be easily observed.

In accordance with one embodiment of the present invention, there is provided an ultrasound system for forming an ultrasound image, comprising: a volume data acquiring unit operable to acquire volume data by transmitting/receiving ultrasound signals to/from a target object of an un-echoic area; and an image processing unit operable to perform inverse volume rendering upon the volume data to form a 3-dimensional image showing the target object and set a region of interest (ROI) on the target object in response to a user input, the image processing unit being configured to detect data corresponding to the ROI from the volume data and reformat the detected data to form a planar image.

In accordance with another embodiment of the present invention, there is provided a method of forming an ultrasound image, comprising: a) acquiring volume data by transmitting/receiving ultrasound signals to/from a target object of an un-echoic area; b) performing inverse volume rendering upon the volume data to form a 3-dimensional image showing the target object; c) setting a region of interest (ROI) on the target object in response to a user input; and d) reformatting data corresponding to the ROI in the volume data to form a planar image.