DE10310389A1 - Measuring device for the defined exercise examination of the lower leg muscles (MR-PEDALO) - Google Patents

Abstract

The invention relates to a measuring device and a measuring method for the defined stress examination of the lower leg muscles in magnetic resonance imaging. DOLLAR A The measuring device presented here has a resistance device for delivering the work to be performed by a subject, a dynamic magnetic resonance tomography unit, evaluation software DOLLAR I1 suitable for blood circulation measurement, evaluation software DOLLAR I2 suitable for the registration of defined muscle work, and one of the statistical software SPSS for Windows on. DOLLAR A The core of the invention is a resistance device which is used to deliver and standardize the muscle work to be performed by the patient.

Description

[State of the art]

The invention relates to a measuring device and a measurement procedure for the defined exercise examination of the lower leg muscles in magnetic resonance imaging. In contrast to previously used measurement methods To examine the peripheral blood flow, it is with dynamic magnetic resonance imaging succeeded in contrast agent inflow, distribution and elimination without the introduction of instruments or ionizing radiation directly measure in the muscle and thus a measure of the blood flow of the interested Derive muscle organ. However, no correlation has been found so far Blood flow data instead. This is due to the fact that so far no suitable Resistance devices were known, which in connection with dynamic magnetic resonance imaging can be used.

As resistance devices are known in the prior art pedal ergometer.

For example, there is a pedal ergometer with a force measuring device DE 4336507 A1 known. However, in contrast to the present invention, the force is measured quite differently, specifically on a bicycle, which has a drive device with a rotating force transmission means for transmitting a tractive force to a driven wheel.

The patent DE 3443126 C2 describes an ergometer, the frame of which consists of a bed, a braking device and two cranks as drive elements.

There are other patent applications which are an ergometer in their way, but they are all out several reasons for the task is not suitable.

The same task is currently underway solved with other methods: with ultrasound, oximetry and the laser.

In the patent DE 69411739 T2 describes a diagnostic device and a method for detailed and accurate examination of patients who have peripheral vascular disease using ultrasound and oximetry. However, the ultrasound can only be used for this purpose to a limited extent, since its resolution is insufficient for small vessels. Oximetry does not provide enough information for a reliable diagnosis of a vascular disease.

The third method with the laser is relatively new to the market. In contrast to magnetic resonance imaging Measurement is a laser or ultrasound measurement over an entire muscle cross-section independently from the distance skin surface to the region of interest (depth of penetration) not possible.

OBJECT OF THE INVENTION

The object of the invention is therefore to create a measuring device and to provide a method, which are capable of the disadvantages or problems listed above mitigate and correct if necessary.

This object is achieved by the Measuring device according to claim 1 or solved by the measuring method according to claim 10.

With the help of the resistance device according to the invention the force, displacement and time measurement of the alternating bilateral Foot flexion and -Extension for the purpose of a load-induced increase in blood circulation performed in the lower leg muscles.

The standardization of from the dynamic MRI-derived intensity-time curves the enrichment of a contrast agent is due to the assignment of these curves for the muscle work performed.

The measuring device presented here has a resistance device for delivering the work to be performed by a subject, a dynamic magnetic resonance imaging unit, evaluation software suitable for blood flow measurement (DynaVision ^© ), evaluation software (Win-Digi ^© ) suitable for the registration of defined muscle work, and statistics Software SPSS for Windows.

• – Keine Verwendung ferromagnetischer Baumaterialien, da die Vorrichtung einem Magnetfeld von mehr als 1 Tesla Feldstärke ausgesetzt werden muss.
• – Abschirmung von elektrischen Bauteilen, die andernfalls zu Störungen des gleichzeitig wirksamen Hoch frequenzfeldes führen und damit die Untersuchungsqualität beeinträchtigen würden.
• – Gewährleistung einer physiologischen, im Untersuchungsgerät unbehinderten Fußflexion und -extension unter Berücksichtung der Ausmaße des tunnelartigen Untersuchungsraums im Magnetresonanztomoqraphiegerät.
• – Fixierung der Schulter zur Vermeidung einer kompensatorischen Rumpfverschiebung bei Verrichtung der Pedalarbeit.

The core of the invention is a resistance device which fulfills all structural requirements for use with an MRI device, namely:

• - No use of ferromagnetic building materials, since the device must be exposed to a magnetic field of more than 1 Tesla field strength.
• - Shielding of electrical components, which would otherwise lead to interference with the simultaneously effective high-frequency field and thus impair the quality of the examination.
• - Ensuring a physiological foot flexion and extension unimpeded in the examination device, taking into account the dimensions of the tunnel-like examination room in the magnetic resonance tomography device.
• - Fixation of the shoulder to avoid a compensatory trunk shift when doing the pedal work.

The developed measuring device is in 1 to 3 shown.

The base plate ( 1 ) the resistance device consists of a plastic-coated chipboard. Their size adapts to the size of the MRI patient table and the examination tunnel of the MRI apparatus. It is placed on the MRI patient table. The measuring apparatus comprises at least one force ( 10 ) and displacement sensor ( 11 ) is mounted on the top end of the plate and is housed in a housing made of a non-ferromagnetic material, preferably copper. The pedals ( 2 ) are attached to the base of the plate. The materials used are of particular importance here, since the entire measuring device must be MRI-compatible, which can only be achieved with non-ferromagnetic materials.

To register the muscle work, which takes place in the magnetic resonance tomography device without repositioning the patient, a multi-channel measuring system is used. The muscle work or the Performance can be measured by measuring the pedal movement in each case the necessary force, the necessary time and the time distance traveled to calculate.

The multi-channel measuring system is a electronic measuring network for measuring the above-mentioned quantities.

The DigiMax system is a digital, microprocessor-controlled measuring device with good reproducibility of the measurement results. The force is measured using force measuring probes, the displacement or angle measurement using digital cable pullers ( 27 ).

The measuring system is an expandable one electronic measuring system for connection to a free serial interface of a PC. Each DigiMax PC 2-channel interface has its own internal Address, about the any device can be addressed in the measurement network from the PC. The system has 2 channels (one for the Way, one for the force), so that here already a force measurement over the Range of motion and thus a number of other statements about performance, Work and speed possible are.

The measuring device is very sensitive electrical high frequency fields, which is why they are made with suitable materials is shielded. Conversely without shielding the measuring equipment the magnetic resonance imaging to disturb and loss of quality (Image artifacts).

The measuring apparatus is located on the head side on the base plate ( 1 ). On the foot side are two foot pedals ( 2 ) appropriate. These are made entirely of plastic. So that the foot can be firmly positioned on the pedals, the pedals ( 2 ) three straps attached with Velcro. A knee pad that can be moved in the longitudinal axis of the support plate ( 15 ) appropriate. Since only the lower leg muscles are to be stressed during the measurements, a shoulder brace ( 8th ) attached to the base plate, which avoids stressing the other muscles. This is with a bearing block ( 7 ) via a set screw ( 21 ), with which it can also be adjusted. For the patient's head there is a head positioning cup ( 22 ) provided on top of the base plate.

Each foot pedal ( 2 ) is with a plastic cable ( 27 ) connected via a pulley ( 16 ) under the base plate ( 1 ) is forwarded to the measuring device.

On the way to the measuring system, the plastic cable ( 27 ) replaced in places by a device for tensioning the train and attaching the displacement measuring system in parallel so that the two parameters (displacement and force) can be measured simultaneously. The rope for the distance measurement is connected to the 11 ) and the cable for force measurement via a pulley ( 16 ) and a connecting element (e.g. elastic interchangeable rubber bands) ( 12 ) with the force sensor ( 10 ) connected. The rubber band ( 12 ) serves as an adjustable counterforce, since individual patients have different muscle status (age, training status, illnesses, etc.) and the system has to be calibrated in order to be able to interpret the measured values individually. Rubber bands with different coefficients of elasticity can be considered. In order to determine the individual muscle status in patients, the isometric measurements are first carried out before the magnetic resonance imaging, wherein an arbitrary maximum force on the part of the patient is applied to the pedal against such a high resistance that there is no pedal movement. The term "isometric measurement" means that the muscle does a static work, ie there is no change in the length of the muscle. For the isometric measurement, the elastic resistance of the rubber band is overridden by a rigid fixation by a set screw through a metal bar bridging the rubber band is achieved.

• – Testart isometrisch
• – Maximale Kraft konzentrisch
• – Schnellkraftanteil pro Sekunde
• – Ausdauerverhalten

For isometric measurement, the following parameters are registered, saved and immediately evaluated by the measuring apparatus using the WinDigi ^® program:

• - Isometric test type
• - Maximum force concentric
• - Rapid power share per second
• - Endurance behavior

Knowing the maximum strength and endurance behavior of the stressed muscles, the pre-tension (elastic resistance) ( 12 ) in the case of foot flexion for the auxotonic measurement. By coupling in rubber bands with different elastic moduli, different torques or load levels can be simulated during active foot flexion.

• – Testart auxotonisch
• – Maximale Kraft konzentrisch
• – Maximale Kraft exzentrisch
• – Minimale Kraft konzentrisch
• – Minimale Kraft exzentrisch
• – Kraftmittelwert konzentrisch
• – Kraftmittelwert exzentrisch
• – Maximale Kraft/Gewicht konzentrisch
• – Maximale Kraft/Gewicht exzentrisch
• – Minimale Kraft/Gewicht konzentrisch
• – Minimale Kraft/Gewicht exzentrisch
• – % Abweichung der Zugkraft zur Druckkraft: konzentrisch
• – % Abweichung der Zugkraft zur Druckkraft: exzentrisch

The characteristic of the auxotonic measurement is the application of a force on the patient or subject side, which leads to a pedal movement in the case of foot flexion. The term "auxotonic Measurement "means that the muscle tension varies with dynamic muscle work. The foot extension determines the extent of the passive pedal return, the distance, time and force of which are registered identically. A movement cycle can thus be numerically and graphically described, which provides information about the following measurement variables:

• - Test type auxotonic
• - Maximum force concentric
• - Maximum force eccentric
• - Minimum force concentric
• - Minimal force eccentric
• - concentric force average
• - Eccentric force average
• - Maximum force / weight concentric
• - Maximum force / weight eccentric
• - Minimum force / weight concentric
• - Minimum force / weight eccentric
• -% deviation of the tensile force to the compressive force: concentric
• -% deviation of the tensile force to the compressive force: eccentric

All listed sizes calculated from force, distance and time data with a measuring frequency of 100 Hz recorded by the sensors installed in the device be partially synchronized with the examination on a screen shown.

The force and displacement sensors ( 10 . 11 ) via a PC interface ( 14 ) connected to the PC. The MRI measurement data are processed and evaluated using the DynaVision® software package. This is designed for a clear demonstration of results using parameter images as well as for exact numerical data output and detailed curve analysis (ROI analysis).

From the strength and the way it can Work will be calculated using the MRI blood flow measurements be correlated.

The measurements with the MRI device are carried out in the idle state before and after 5 minutes of exposure using MR-PEDALO. The work done by MR-PEDALO increases the blood flow in the lower leg muscles. The force used and the distance traveled are recorded over time with the WinDigi ^® software package and displayed graphically. Completely independently of this, the DynaVision ^® software uses magnetic resonance imaging to measure the blood flow using contrast medium inflow and washout curves over muscle cross-sections of interest.

While The patient should be actively alternating plantar flexion during storage in the magnetic resonance imaging device and perform dorsal texts. The measurement takes about 35-40 minutes and starts with the start of a contrast agent bolus application (2 ml / s) over a 22G cubital cannula.

There is a coil (1 Tesla) inside the MRI machine, and another coil is placed on the patient's leg and fixed with adhesive fasteners.

[Examples]

Embodiments are in the Drawings 1 to 3 shown:

1 shows the side view of the measuring device according to the invention.

2 shows the measuring device according to the invention from below.

3 shows the measuring device according to the invention from above.

1

baseplate

2

pedal

3

bearing block

4

Umlenkrollenhalter

5

communications circuit

6

guide part

7

bearing block for shoulder braces

8th

Shoulder backstop

9

copper case

10

force sensor

11

displacement sensor

12

elastic interchangeable connecting element

13

connecting part

14

PC interface

15

Knee pad (if necessary)

16

guide rollers for connecting train (Force sensor)

17

guide rollers for connecting train (Displacement sensor)

18

communications circuit (Displacement sensor)

19

idler pulley (Displacement sensor)

20

bracket for force sensors

21

screw for shoulder braces

22

head support for shoulder braces

23

row of holes for shoulder braces

24

row of holes for knee pad

25

row of holes for lower leg storage

26

Clamps for fasteners

27

cable

Claims (14)

Measuring device for the non-invasive measurement of the muscular blood flow in the human lower leg as a function of the mechanical load, comprising a resistance device, an associated computer unit, software for providing and evaluating blood flow measurements using an MRI device, evaluation software suitable for the registration of defined muscle work, and one the statistics software for Windows, an MRI device and a second induction coil, characterized in that the resistance device has a mechanical device consisting of non-ferromagnetic building materials for the transmission of work performed by means of a force transmission means and an elongated design, so that the resistance device can be inserted into conventional MRI devices is. Device according to claim 1, characterized in that the adjustable resistance device is a couch with pedals, a power transmission means and a measuring apparatus for measuring the force given, the covered Way and time of activity the resistance device. Device according to claim 1 to 2, characterized in that that the resistance device has several adjustable resistance levels having. Device according to claims 1 to 3, characterized in that that the measuring equipment on both sides e.g. one for each lower leg Test subjects have a force sensor for detecting those transmitted via a force transmission means Has force component. Device according to claims 1 to 4, characterized in that that the measuring apparatus has a displacement sensor on both sides for detecting the Has path component. Apparatus according to claims 1 to 5, characterized in that the resistance device has a shoulder counter-holder ( 8th ), so that only the lower leg muscles are used when the pedals are pressed. Device according to claim 2, characterized in that the bed is made of plastic-coated chipboard, their dimensions adapted to the patient positioning table of the magnetic resonance imaging device is. Device according to claim 2, characterized in that the measuring equipment for shielding is housed in a housing is. Apparatus according to claim 8, characterized in that the housing, in which the measuring apparatus is housed, from a non-ferromagnetic Fabric, especially made of copper. Measurement method for non-invasive measurement of tissue perfusion in the lower leg muscles using the device one of the claims 1 to 9, the method comprising the following steps: - blood flow measurements using an MRI machine, - Provide and evaluating the blood flow measurement data before exposure to the MR-PEDALO using suitable software, - Burden of the test person to be examined by the force output against the Resistance device with predefined resistance, - blood flow measurements using an MRI machine the burden, - Provide and evaluating the blood flow measurement data after exercise the MR-PEDALO using suitable software, - correlation the intensity-time curves from the dynamic MRI before exercise and after exercise, with novel standard values for muscle circulation in the human lower leg. A method according to claim 10, characterized in that the measured values (force and distance) are registered over time and being represented. A method according to claim 10, characterized in that the blood flow is free on the basis of contrast medium inflow and washout curves selectable Lower leg muscle cross sections measured becomes. A method according to claim 10, characterized in that the provision and evaluation of the blood flow measurement data is carried out by means of an MRT device by a specific evaluation software DynaVision ^© . Method according to claim 10, characterized in that the registration of defined muscle work has been carried out by means of the DigiMax ^© software.