WO2013128314A1

WO2013128314A1 - Vessel scan planning method

Info

Publication number: WO2013128314A1
Application number: PCT/IB2013/051132
Authority: WO
Inventors: Raymond Joseph Elisabeth Habets; Jeroen Jozef SONNEMANS; Liesbeth Geerts-Ossevoort
Original assignee: Koninklijke Philips N.V.
Priority date: 2012-02-27
Filing date: 2013-02-12
Publication date: 2013-09-06

Abstract

A method of planning and conducting a set of magnetic resonance (MR) scans with an MR scanner (12), comprising the following steps (48-60): (1a) using a set of MR data that describes a tubular object of interest (32), displayed on a display unit (16), to determine a location (36, 38, 40) at the tubular object of interest (32) for an MR scan to be carried out with the MR scanner (12), wherein the location (36, 38, 40) lies in a scan plane of the MR scan; (lb) by using an analyzing tool, automatically determine parameters describing a plane that is essentially exactly perpendicularly arranged to a direction of extension (34) of the tubular object of interest (32), wherein a center of the scan plane lies inside the tubular object of interest (32), and wherein the scan plane has a field of view that encompasses the tubular object of interest (32); (1c) store the parameters in a memory unit (22) that is accessible by a control unit (20) that is provided to control the MR scanner (12); (1d) repeat steps (la) to (1c) as often a desired, so that the stored parameters constitute a plan of scan planes to be scanned; (1e) consecutively carry out MR scans in accordance with the plan of scan planes; an application software provided to carry out the method; a control station (14) for controlling an MR scanner (12), comprising a control unit (20) and an application software module (24) including the application software.

Description

Vessel scan planning method

FIELD OF THE INVENTION

The invention pertains to a method of planning and conducting a set of magnetic resonance (MR) scans with an MR scanner, application software representing the methods, and a control station to execute the application software.

BACKGROUND OF THE INVENTION

Magnetic resonance imaging (MRI) is a well-established diagnostic procedure, in particular in the field of vascular examination. Besides producing anatomical images without the presence of bone, MRI can produce many additional contrasts that provide a great diversity of information about the vascular system. Among others, a magnetic resonance (MR) scanner can produce images of lumen, vessel wall, plaque, and flow. Vessel wall, plaque and flow scans benefit from a scan planning that is orthogonal to the vessel, as accuracy of derived quantities such as maximum flow speed or vessel wall thickness is improved with orthogonal scan planning.

In scan planning for vessel anatomies, it is known to use a default scan planning tool that is commonly implemented in control stations provided to control the MR scanner. Each planned scan plane has to be planned separately. When using scan planning tools of the prior art, it is quite often perceived as difficult and time consuming by an operator to exactly plan the scanning planes that lie orthogonal to the vessel. Another challenge with scan planning for plaque and flow measurements is to find exact locations where the scans should favorably be made.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a scan planning method for an MR scanner with an improved ease of use for planning orthogonal scan planes through tubular shaped objects.

In one aspect of the present invention, the object is achieved by a method of planning and conducting a set of magnetic resonance (MR) scans with an MR scanner, comprising the following steps: (a) using a set of MR data that describes a tubular object of interest, displayed on a display unit, to determine a location at the tubular object of interest for an MR scan to be carried out with the MR scanner, wherein the location lies in a scan plane of the MR scan;

(b) by using an analyzing tool, automatically determine parameters describing a plane that is essentially exactly perpendicularly arranged to a direction of extension of the tubular object of interest, wherein a center of the scan plane lies inside the tubular object of interest, and wherein the scan plane has a field of view that encompasses the tubular object of interest;

(c) store the parameters describing the plane in a memory unit that is accessible by a control unit that is provided to control the MR scanner;

(d) repeat steps (a) to (c) as often a desired, so that the stored parameters constitute a plan of scan planes to be scanned;

(e) consecutively carry out MR scans in accordance with the plan of scan planes.

The set of MR data that describes a tubular object of interest may preferably be an image from a maximum intensity projection (MIP), providing an outline image ('scout scan') of the tubular object of interest and its surroundings.

Analyzing tools that automatically determine parameters describing a plane that is essentially exactly perpendicularly arranged to the direction of extension of the tubular object of interest are well-known in the field of MR scanners. For instance, a method of calculating gradients to the surface of a tubular vessel at a starting point from acquired scan data, and deriving a mathematical normal that is perpendicularly arranged to the gradients, is described in document WO 01/26055 B2. Parameters describing a scan plane that is orthogonally oriented to the mathematical normal can readily be obtained.

The phrase "perpendicularly arranged plane", as used in this application, shall be understood particularly as a detail of an in principle infinite plane that is arranged perpendicular to a direction that is made reference to, wherein the detail of the plane includes a cross-sectional view of the tubular object of interest, and wherein a field of view

encompasses the cross-sectional view of the tubular object of interest.

The invention is based on the concept that by using the described method, an accurate geometry of planned scan planes that lie orthogonal to the direction of extension of the tubular object of interest is favorably available beforehand, such that a correlation between acquired MR data and their pertinent geometrical locations is available right after acquiring the MR data, and any cumbersome fitting of geometrical data becomes

unnecessary. In another aspect of the present invention, the method further comprises the following steps:

assign acquired data of the MR scan to geometrical data of the scan plane; display the acquired data of the MR scan using the assigned geometrical data of the scan plane.

Thus, as the geometrical data of the scan plane are available before the scan data are acquired, geometry data and acquired scan data may be readily assigned to each other. This will advantageously turn the process of selecting locations where scan data are to be acquired into a 'closed loop imaging' process: after determining the locations, an orientation of the orthogonal scan plane is fed back to the MR scanner that will acquire the planned scan data.

Even more advantageous, acquired scan data may then automatically be processed using a software processing tool, and processed data derived from the scan data may be fed back to be displayed on the display of the MR scanner, so that image data exactly perpendicular to the direction of extension of the tubular object of interest can readily be obtained and, for instance, be used for further plaque or blood flow analysis, thus presenting results of such analyses in their anatomical context.

By employing this step in the method, the planning process may become fully interactive: a direct analysis of data from the tubular object of interest (e.g. vascular data) is followed by determining a location of interest for further plaque or flow scanning.

In a further embodiment of the invention, the location at the tubular object of interest may be a region in which a flow scan is to be carried out. After processing, the results are fed back for inspection on the display.

The method of the invention may advantageously be applied in an analysis of plaque burden of a vessel and its composition. Using a range of locations for carrying out plaque scans would allow for scanning at planes that are exactly orthogonally aligned with regard to the vessel. Moreover, an assignment of plaque slab data to vessels would be readily available without any need of fitting data together.

In a further aspect of the invention, step (a) of using a set of MR data that describes the tubular object of interest, displayed on the display of the MR scanner, to determine the location at the object of interest for an MR scan to be carried out with the MR scanner, wherein the location lies in a scan plane of the MR scan, is performed from a site that is remote to a site of installation of the MR scanner. Thus, medical experts like cardiologists, radiologists or vascular surgeons, often fully occupied people, do not have to travel to or to be on the site of installation of the MR scanner at all, to be able to give their expertise on where MR scans should preferably be carried out, whereby time and costs for a pertaining examination may be saved.

It is another object of the invention to provide an application software to carry out at least one of the methods disclosed herein, wherein the method is converted into a program code that is implementable in and executable by a control unit that is provided to control an MR scanner by carrying out the method.

It is yet another object of the invention to provide a control station for controlling an MR scanner. The control station comprises a control unit and an application software module residing in the control unit, and which the application software module that includes the application software is executable by.

The control station may further comprise a user interface, provided for enabling at least one step of one of the methods disclosed in this application. A user interface may provide a commonly means for selecting and activating portions of the application software that represents one of the disclosed methods. In the environment of the user interface for controlling the MR scanner, application software options for planning and conducting a set of MR scans in accordance with the invention may readily be implemented. A combination of the application software module with features of a software analyzing tool that is commonly available with the MR scanner, provides a variety of further options of visualization. For instance, a combination of plaque scan analysis results with a vessel segmentation may allow for mapping the plaque analysis results onto an outside of the vessel segmentation to show a plaque composition underneath the vessel wall.

The control station may further comprise a display formed by a customary monitor screen that is furnished with options for medical application, facilitating easy navigation for the user and visualizing quantified analyses results.

In a preferred embodiment, the control station further comprises a remote control unit to determine a location, using a set of MR data that describes an object of interest, for an MR scan to be carried out with the MR scanner, from a site that is remote to a site of installation of the MR scanner. The remote control unit may have a receiving unit to receive signals sent by a computer located anywhere via internet, or via intranet, using a LAN/WLAN ((Wireless) Local Area Network) connection. BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. Such embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention.

In the drawings:

Fig. 1 is a schematic view illustrating a configuration of an MR scanner and a control station according to an embodiment of the invention,

Fig. 2 illustrates a flowchart describing a method of planning and conducting MR scans in accordance with the invention,

Fig. 3 shows results from conducted MR scans as visualized on the control station.

DETAILED DESCRIPTION OF EMBODIMENTS

Fig. 1 shows a schematic view of a magnetic resonance (MR) system 10 configured and installed on a site of a medical center, comprising an MR scanner 12 and a control station 14 for controlling the MR scanner 12. The control station 14 is designed as a work station and is provided to control image acquisition with the MR scanner 12 as well as processing of images acquired by the MR scanner 12. The control station 14 has a monitor that is customarily designed as a display unit 16 for medical applications and that allows for a visualization of several high-resolution images and that thus constitutes a part of a user interface 18 for an operator of the MR system 10.

In order to fulfill the above-mentioned control functions, the control station 14 comprises a plurality of application software modules 24 that are residing in a control unit 20 of the control station 14. The plurality of application software modules 24 is executable by the control unit 20 to carry out the control functions. One of the application software modules 24 comprises an application software that is provided to carry out the method subsequently described herein. The steps 48-64 of the method are converted into a program code of the application software module 24 that is implementable in and executable by the control unit 20 that is provided to control the MR scanner 12 by carrying out the method in a well-known manner which needs no further explanation to a person of skill in the art. The control station 14 further comprises several memory units 22 that are provided to store data acquired by the MR scanner 12, and that the control unit 20 has access to. In Fig 1, only a single memory unit 22 is exemplarily shown. The user interface 18 of the control station 14 includes several interface members for giving input by the operator of the MR system 10 to the control unit 20, among those a computer mouse, a keyboard and a graphic tablet. The user interface 18 is, among others, provided for enabling a number of steps 48-64 of the methods subsequently described herein, by the operator.

Further, the control station 14 comprises a remote control unit 26 to carry out the steps 48-64 of the methods subsequently described herein from a site that is remote to a site of installation of the MR scanner 12. For that purpose, the remote control unit 26 has a remote control receiving unit 28 that is connected to an intranet network of a medical center via a Local Area Network (LAN) connection, and a remote control transmitting unit 30 that is connected to a circuitry of the control unit 20. Input to the control unit 20 can thereby be given by a medical expert from a site with an access to the local area network that is remote to a site of installation of the MR scanner 12, so as to enable a number of selected steps 48-64 of the methods subsequently described herein.

Fig. 2 illustrates a method of planning and conducting a set of magnetic resonance (MR) scans with the MR scanner 12 in a flow chart. In the first step 48, a set of medical MR data describing a tubular object of interest 32, for instance a blood vessel such as an artery, which has a direction of extension 34, is displayed on a center portion of the display unit 16. Fig. 3 shows an MIP (maximum intensity projection) view 42 of tubular objects of interest 32 which are an aortic bifurcation and common iliac arteries of a patient. It should be noted for clarity that the direction of extension 34 does not necessarily lie in the view plane of the MIP view. In the next step 50, using the application software and the mouse, the operator is able to select a position within the MIP view to determine a location 36, 38, 40 at the tubular object of interest 32, here one of the iliac arteries, for an MR scan to be carried out with the MR scanner 12, wherein the location 36, 38, 40 lies in a scan plane of the MR scan. The selected position is marked in the MIP view by a ring, indicating the location 36, 38, 40 of the scan plane.

In the next step 52, by using an analyzing tool that is part of the application software, parameters are automatically determined that describe a plane that is essentially exactly perpendicularly arranged to the direction of extension 34 of the iliac artery which is the tubular object of interest 32, and that the location 36, 38, 40 lies in. The determination of the plane parameters is carried out by calculating gradients to a surface of the iliac artery, at the selected location 36, 38, 40 from the acquired MIP scan data, and deriving a

mathematical normal that is perpendicularly arranged to the gradients. Next, parameters describing a scan plane that is orthogonally oriented to the mathematical normal are readily obtained with the analyzing tool. The scan plane is described in terms of the parameters such that a field of view of the calculated scan plane encompasses a cross-sectional view of the tubular object of interest. In the MIP view, the ring that represents the selected location 36, 38, 40 is oriented to lie in the calculated scan plane.

In the following step 54, the calculated plane parameters are stored in the memory unit 22 that is accessible by the control unit 20.

The steps 50-54 of selecting a position within the MIP view to determine a location 36, 38, 40 at the tubular object of interest 32 and the automatic determination of parameters of a plane that is perpendicular to the tubular object of interest 32 at the location 36, 38, 40 is repeated as often as desired by the operator (decision step 56). Via the remote control unit 26 of the control station 14, a medical expert sitting in an office remote to the site of installation of the MR scanner 12, can look at an identical view of the MR data on another computer monitor, and can be consulted by performing the step 50 of determining a location 36, 38, 40 for a scan to be carried out by using a computer mouse as part of the user interface 18.

In this way, the stored parameters of the planes selected by the operator and/or the medical expert constitute a plan of scan planes to be scanned with the MR scanner 12.

On acknowledging by an operator mouse click in the next step 60, the MR scanner 12 consecutively carries out MR scans in accordance with the plan of scan planes to acquire MR scan data.

In another step 62, the MR scan data are automatically assigned to geometrical data of the pertinent scan plane which are exactly known from the set of plane parameters. By that, the acquired MR data are directly linked to their exact geometry data. As part of the step 62, an automatic processing is also carried out by using a software processing tool. The automatic processing in the step 62 allows for a quantization of properties of the tubular object of interest 32 that is conducted free from operator influences, and in a scan plane that is exactly perpendicular to the direction of extension 34 of the tubular object of interest 32.

The acquired and processed data of the MR scan can then readily be displayed in another step 64, using the assigned geometrical data of the scan plane. On the upper right side of the monitor in Fig. 3, a cross-sectional view 44 of the tubular object of interest 32 in an exactly orthogonal scan plane at the selected location 36, 38, 40 is shown as an inlay of the original ring. In addition, a cross-sectional view 46 of the tubular object of interest 32 in a plane the direction of extension 34 of the tubular object of interest 32 lies in is given in the lower right side of the monitor.

Even further below on the right side of the monitor, the cross-sectional MR data 66 acquired at the various determined locations 36, 38, 40 with the scans according to the scan plan are displayed and can be selected to be shown on the display unit 16 in an enlarged view.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

REFERENCE SYMBOL LIST:

10 magnetic resonance system

12 magnetic resonance scanner

14 control station

16 display unit

18 user interface

20 control unit

22 memory unit

24 software module

26 remote control unit

28 remote control receiving unit

30 remote control transmitting unit

32 object of interest

34 direction of extension

36 location

38 location

40 location

42 maximum intensity projection view

44 cross-sectional view

46 cross-sectional view

48 step

50 step

52 step

54 step

56 decision step

58 step

60 step

62 step

64 step

66 cross-sectional MR data

Claims

CLAIMS:

1. A method of planning and conducting a set of magnetic resonance (MR) scans with an MR scanner (12), comprising the following steps (48-60):

(la) using a set of MR data that describes a tubular object of interest (32), displayed on a display unit (16), to determine a location (36, 38, 40) at the tubular object of interest (32) for an MR scan to be carried out with the MR scanner (12), wherein the location (36, 38, 40) lies in a scan plane of the MR scan;

(lb) by using an analyzing tool, automatically determine parameters describing a plane that is essentially exactly perpendicularly arranged to a direction of extension (34) of the tubular object of interest (32), wherein a center of the scan plane lies inside the tubular object of interest (32), and wherein the scan plane has a field of view that encompasses the tubular object of interest (32);

(lc) store the parameters describing the plane in a memory unit (22) that is accessible by a control unit (20) that is provided to control the MR scanner (12);

(Id) repeat steps (la) to (lc) as often a desired, so that the stored parameters constitute a plan of scan planes to be scanned;

(le) consecutively carry out MR scans in accordance with the plan of scan planes.

2. The method as claimed in claim 1, further comprising the following steps (62, 64):

- assign acquired data of the MR scan to geometrical data of the scan plane;

display the acquired data of the MR scan using the assigned geometrical data of the scan plane.

3. The method as claimed in claim 2, further comprising the following step (58): - using a software processing tool, automatically process the data of the MR scan before displaying them.

4. The method as claimed in claim 1, wherein step (la) is performed from a site that is remote to a site of installation of the MR scanner (12).

5. An application software provided to carry out the method as claimed in any of claims 1 to 4, wherein the method is converted into a program code that is implementable in and executable by a control unit (20) that is provided to control an MR scanner (12) by carrying out the method.

6. A control station (14) for controlling an MR scanner (12), comprising a control unit (20) and an application software module (24) residing in the control unit (20), which the application software module (24) that includes the application software as claimed in claim 5 is executable by.

7. The control station (14) for controlling an MR scanner (12) as claimed in claim 6, further comprising a user interface (18), provided for enabling at least one step (48- 64) of one of the methods as claimed in claims 1 to 4.

8. The control station (20) for controlling an MR scanner (12) as claimed in claim 6, further comprising a remote control unit (26) to carry out the method as claimed in claim 4 from a site that is remote to a site of installation of the MR scanner (12).