Open type magnetic resonance imaging system which allows for easy access to the patient being examined

A magnetic resonance imaging system includes a lower body which has a flat upper surface, and contains a first magnetic pole, an upper body which has a lower surface disposed in opposed relation to the upper surface of the lower body, and contains a second magnetic pole, a bed disposed adjacent to the lower body, and a pair of support posts which are provided respectively on right and left sides of the lower body, and interconnect the lower body and the upper body. A space, formed between the lower surface of the upper body and the upper surface of the lower body, is open at least toward the bed between the pair of right and left support posts.

BACKGROUND OF THE INVENTION 
This invention relates generally to a magnetic resonance imaging system 
(hereinafter referred to as "MRI system"), and more particularly to a MRI 
system in which considerations, contributing to easy handling, are given 
to the subject to be examined (hereinafter referred to as "patient"), and 
also the efficiency of operations, such as a medical treatment to be given 
to the patient by a doctor, and an examination operation to be effected by 
a technician or the like (The doctor and the technician will hereinafter 
be referred to as "doctor or the like"), is improved. 
A MRI system utilizes nuclear magnetic resonance (NMR) phenomena to provide 
an image of a cross-sectional area of that portion of the patient to be 
examined for diagnostic purposes. In such a MRI system, in order to 
produce NMR phenomena on the patient's portion to be examined, it is 
necessary to produce a strong magnetic field and then to locate the 
patient's portion to be examined in this magnetic field. 
In conventional MRI systems, generally, a bore such as a tunnel is formed 
in a strong magnetic field, and the patient is put into this bore. In such 
a system, although the strong magnetic field can be easily formed, the 
patient must be loaded into the narrow bore, which has invited a problem 
that the examination can not be carried out easily. Japanese Patent 
Unexamined Publication No. 62-26052 discloses a MRI system not using a 
tunnel space, in which one side of a measurement space is open. 
In the conventional MRI systems, the measurement space is formed in the 
tunnel, or is open at its one side with the remaining sides closed by 
walls. Therefore, when the patient is inserted into the measurement space 
for examination purposes, he tends to feel oppressed and uneasy, and it 
has often been difficult to properly examine a patient having 
claustrophobia. Moreover, the doctors or the like have now increasingly 
desired to give a medical treatment to the patient simultaneously with the 
examination operation; particulerly when the patient has an emergency 
condition, it is necessary to effect a medical treatment simultaneously 
with the examination. In such a case, the doctors or the like need to gain 
access to the patient from opposite sides of the patient. With 
conventional MRI systems, however, it has been impossible to achieve this. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a magnetic resonance 
imaging system capable of decreasing oppressed or uneasy feelings in 
patients to be examined during examination. And, it is another object of 
the present invention to provide a magnetic resonance imaging system in 
which doctors or the like can easily effect an operation of the 
examination or a medical treatment at the same time during the 
examination. 
In order to achieve such objects of the present invention, there is 
provided a magnetic resonance imaging system including a lower body which 
has a flat upper surface and contains a first magnetic pole, an upper body 
which has a flat lower surface disposed in opposed relation to the upper 
surface of the lower body and contains a second magnetic pole, the lower 
body and the upper body forming an examination space, and a pair of 
support posts which are provided respectively on sides of the examination 
space, i.e. both side surfaces of the lower body. These support posts 
interconnecting the lower body and the upper body; the examination space 
being open at least toward a bed between the pair of support posts. 
In order to achieve further the above objects according to the present 
invention, the support posts are located outside the lower body, and are 
fixed to the side surfaces of the lower body which extend toward a rear 
side thereof from a connecting portion of the lower body and the bed. A 
space is provided for permitting the effecting of a medical treatment at 
the same time during the doctor's examination as needed at the side 
surfaces thereof between the support posts and the connecting portion of 
the lower body.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
One preferred embodiment of the present invention will now be described 
with reference to FIGS. 1 to 3. 
FIG. 1 is a perspective view of a MRI system of the invention as seen at an 
angle from the front side thereof. A body of this MRI system includes a 
lower body 40 having a substantially circular upper surface, an upper body 
70 which is disposed above the lower body 40, and has a substantially 
circular lower surface, a pair of opposed right and left support posts 62 
and 64 which interconnect the lower body 40 and the upper body 70 in such 
a manner that the lower body 40 and the upper body 70 are disposed 
generally between the two support posts 62 and 64. At a front side of the 
MRI system body of FIG. 1, that is, at one side of the two support posts 
62 and 64, a bed 10 is disposed adjacent to the lower body 40 through a 
connecting portion 42. In this MRI system, the patient is placed on the 
bed 10, and is transferred or loaded to the lower body 40. In the lower 
body 40, an examination is effected using known magnetic resonance 
phenomena, and results of the examination are displayed as an image in a 
display portion of a central operating device (not shown). 
The bed 10 includes a bed body 14, a top plate 12 mounted on the bed body 
14, and a bed leg 18. The top plate 12 is driven to move in longitudinal 
and transverse directions of the bed 10 by a drive device contained in the 
bed 10. A pair of bed side portions 16, made of a soft material, such as 
foamed urethane, sponge or rubber, are provided at opposite lateral sides 
of the bed body 14, respectively, and these bed side portions 16 prevent 
the patient from injury while he moves onto the bed, and also absorb an 
impact force produced when a stretcher, on which the patient is placed, is 
brought into contact with the lateral side of the bed 10. After the 
patient is placed on the bed 10, the top plate 12 is moved forward, 
backward, right and left, so that the patient can be accurately loaded to 
the lower body 40. This operation can be carried out by any one of a pair 
of operating devices 72 and 74 which are mounted respectively on right and 
left portions of a front side of an outer peripheral surface of the upper 
body 70 facing the bed 10, a rear operating device 75 which is mounted on 
the rear side of the outer peripheral surface of the ceiling portion 70, 
and the central operating device (See FIGS. 1 to 3). The leg 18 of the bed 
10 is much smaller in cross-sectional area than the bed body 14, and is 
disposed at a central portion of the bed body 14, and the outer periphery 
of the leg 18 is sufficiently recessed inwardly from the outer periphery 
of the bed body 14, thus providing a sufficient space at the feet of the 
doctors or the like that the they can move freely around the bed. This 
facilitates the examination operation. 
The upper surface of the lower body 40 is disposed in opposed relation to 
the lower surface of the upper body 70, and the lower body 40 and the 
upper body 70 contain respective opposed inclined magnetic field coils, 
irradiation coils, receiving coils and magnetic poles, and circular yokes 
47 and 79 for these parts are also contained respectively in the lower 
body 40 and the upper body 70, as shown in FIG. 6. The lower body 40 has 
the bed connecting portion 42 formed at a central portion of the front 
side thereof for connection to the bed 10. A pair of outer peripheral 
surfaces (arcuate surfaces) 46 and 48 of the lower body 40, which lie 
between one end of the bed connecting portion 42 and the right support 
post 62 and between the other end of the bed connecting portion 42 and the 
left support post 64, respectively, are substantially part of a 
cylindrical surface having its axis disposed on an axis 41 of the lower 
body 40. With this construction, the doctor or the like can move the 
patient from either of the right and left outer peripheral surfaces 46 and 
48 according to the need, and also when the patient to be examined 
requires the attendance of a nurse or a medical treatment, a necessary 
medical instrument, such as an oxygen mask and an instillator, can be 
applied to the patient from the right and left outer peripheral surfaces 
46 and 48. The lower body 40 has a circular shape, and that surface of the 
bed connecting portion 42 facing the bed 10 is straight so as to 
accurately connect the circular lower body 40 to the bed and also to 
lessen the burden on the patient during transfer of the patient to the 
lower body 40. 
An upper peripheral edge of the lower body 40 is chamfered or cut off to 
provide a chamfered or beveled portion 52. The chamfered portion 52 is 
made of a soft material. With this construction, the doctors or the like 
and the patient are prevented from being injured by the upper edge of the 
lower body 40, and also the doctors or the like can easily approach the 
patient. A lower peripheral edge portion of the lower body 40 is recessed 
as at 54, thus providing a space at the feet of the doctors or the like so 
that they can easily move around the lower body 40 during the examination 
and a medical treatment. 
The front side (surface) and opposite lateral sides (surfaces) of the upper 
body 70 continuous therewith are defined by a substantially semi-circular 
surface, and therefore the degree of opening of an measurement space is 
high, so that the patient feels less oppressed. In addition, because of 
this widely-open arrangement, the doctors or the like can effect the 
operation easily. A lower peripheral edge of the upper body 70 is 
chamfered or cut off to provide a chamfered or beveled portion 82, and 
this chamfered portion 82 is made of a soft material. With this 
construction, even if the doctors or the like hit their head against this 
edge during the operation, they will not be injured. 
The lower body 40 and the upper body 70 are interconnected by the pair of 
right and left support posts 62 and 64 provided respectively on opposite 
(right and left) sides of the lower body 40 and the upper body 70 as seen 
from the bed 10 (FIG. 1) in such a manner that the lower body 40 and the 
upper body 70 are interposed between the two support posts 62 and 64. A 
magnetic circuit is formed in these support posts 62 and 64, and is 
connected to the magnetic poles provided respectively within the lower 
body 40 and the upper body 70. A circular yoke 67 is contained in each of 
the two support posts 62 and 64, as shown in FIG. 6. The right and left 
support posts 62 and 64 are spaced apart from the lower body 40, so that a 
space is formed between the outer periphery of the lower body 40 and the 
outer periphery of each of the two support posts 62 and 64. As a result, a 
space 66 is formed between the inner side of the right support post 62 and 
the outer periphery of the measurement space formed between the lower body 
40 and the upper body 70 whereas a space 68 is formed between the inner 
side of the left support post 64 and the outer periphery of the 
measurement space. The support posts 62 and 64 are formed into a generally 
square cross-section, so that extension portions, which constitute side 
tables 76 and 78, respectively, are formed respectively at the bottoms of 
these spaces 66 and 68. With this construction, the patient placed on the 
lower body 40 can feel easy, and also when applying a medical treatment to 
the patient, medical instruments can put on the side tables 76 and 78, and 
the doctors or the like can effect the operation easily. Illumination 
means 61 and 63 can be provided respectively on the inner sides of the 
right and left support posts 62 and 64 respectively facing the spaces 66 
and 68, or on the side tables 76 and 78, respectively. In this case, the 
space is made brighter, so that the patient can feel less oppressed, and 
also the doctors or the like can effect the operation more easily, which 
prevents errors in the operation. The right operating device 72 is 
provided in the outer peripheral surface of the upper body 70, and is 
disposed between the front side thereof which faces the bed 10 and the 
right support post 62, whereas the left operating device 74 is provided in 
the outer peripheral surface of the upper body 70, and is disposed between 
the front side thereof and the left support post 64. Further, the rear 
operating device 75 is provided in the rear surface of the upper body 70 
lying between the two support posts 62 and 64, as shown in FIG. 3. With 
this arrangement, the doctor or the like, even if positioned at any of the 
right, left and rear sides of the lower body 40, can effect the operations 
such as the movement of the bed 10 and the start and interruption of the 
examination operation. 
The space, formed by the lower body 40 and the upper body 70, is also wide 
open at the rear side as shown in FIG. 3. This open construction is 
obtained by recessing the rear sides of the lower body 40 and the upper 
body 70 over a wide range between the two support posts 62 and 64. More 
specifically, a recess 71 is formed in the rear side of the outer 
periphery of the lower body 40, and a recess 73 is formed in the rear side 
of the outer periphery of the upper body 70. With this construction, the 
distance from the rear side to the center of the lower body 40 is reduced, 
so that the operation can be effected easily in the measurement space. 
In the above embodiment, as shown in FIG. 6, the support posts have the 
surfaces not opposed to the lower body as formed as large curved surfaces. 
Although it is described above that the support posts have a generally 
square crosssection, all the side surfaces thoseof may be made straight, 
the crosssections may be square, and all corner portions of the support 
posts may be cut off. 
A central light marker 92 is mounted on the front side of the cut portion 
82 provided in the outer peripheral surface of the upper body 70 adjacent 
to its lower surface, and a pair of side light markers 94 and 96 are 
provided on the side surfaces of the right and left support posts at the 
sides of the examination space 62 and 64, respectively. These light 
markers 92, 94 and 96 emit light beams serving as a reference of the 
positional relation. 
FIG. 4 is a view showing the doctor or the like conducting the examination 
while sitting on a chair. A height L1 of the upper surface of the lower 
body 40 is in the range of between 600 mm and 800 mm so that the doctor or 
the like can put his head into the measurement space formed between the 
upper surface of the lower body 40 and the lower surface of the upper body 
70. A height L3 of the lower surface of the upper body 70 from a floor 
surface on which the lower body 40 is mounted is set to 1,285 mm in this 
embodiment. Preferably, this height L3 is in the range of between 1,000 mm 
and 1,550 mm. In order to enhance the resolution of the image obtained as 
the examination result, it is desirable that the distance or spacing 
between the upper surface of the lower body 40 and the lower surface of 
the upper body 70 be small, and for this reason the height L3 is set to 
1,285 mm. A vertical dimension L2 of the measurement space between the 
upper surface of the lower body 40 and the lower surface of the upper body 
70 is in the range of between 350 mm to 435 mm. With this value, the 
patient, lying down on the lower body 40, can move both hands, and if this 
dimension is increased, the patient can move his hands more easily, but 
the precision of the examination is lowered. 
The lower body 40 has the chambered portion 52 formed at the upper 
peripheral edge thereof, and the upper body 70 has the chamfered portion 
82 formed at the lower peripheral edge thereof. Therefore, the doctors and 
other attending personnel are prevented from being injured upon striking 
against these edges. The recess 54 is formed at the lower peripheral edge 
portion of the lower body 40, and therefore the nails of the foot of the 
doctor or the like will not strike against this lower end. FIG. 5 is a 
view showing the doctor or the like effecting the operation while standing 
up at the lateral side of the lower body 40. Since the lower peripheral 
edge of the upper body 70 is cut off or chamfered, the doctor or the like 
can better look into the measurement space above the lower body 40, so 
that the operation can be carried out easily. The lower peripheral edge of 
the upper body 70 may be chamfered over the entire periphery thereof to 
provide the chamfered portion 82 either in such a manner that the outer 
peripheral surface thereof is straight in transverse cross-section as 
indicated at the left of FIG. 5, or in such a manner that the outer 
peripheral surface is rounded in transverse cross-section as indicated by 
a broken line at the right. In FIG. 5, preferably, an inclination angle 
300 is in the range of between 40.degree. and 75.degree.. In the case 
where the chambered portion 82 has the rounded peripheral surface, the 
radius of curvature thereof is preferably in the range of between 50 mm 
and 80 mm. As shown in FIGS. 1 and 3, the upper surface of the upper body 
70 is flat at its outer peripheral portion, and the remainder surrounded 
by this outer peripheral portion is slightly outwardly convex to assume a 
dome-like configuration, thereby increasing the strength. 
FIG. 6 is a view showing the doctor or the like standing up at the lateral 
side of the lower body 40. The center or axis 41 of the lower body 40 
coincides with the center of the measurement space, and it is preferred 
that portion of the patient to be examined should be disposed on this 
center 41. In this condition, the doctors or the like can be positioned 
accurately at the opposite sides of the lower body 40, and hence at the 
opposite sides of the patient, respectively, and therefore the various 
operations can be carried out efficiently. The light markers 92, 94 and 96 
accurately indicate a reference position 141 of the bed and the reference 
position 41 of the measurement space by light beams emitted therefrom. The 
patient is properly positioned by the reference position 141 of the bed 
10, and then is automatically moved or transferred into the reference 
position in the measurement space. At this time, however, if the patient 
moves himself, a deviation results from this movement. In this case, the 
doctors or the like must again position the patient with respect to the 
reference position in the measurement space; however, since the light 
markers 92, 94 and 96 can indicate the position of the center of the 
measurement space, the position of the patient can be easily corrected 
accurately. 
FIG. 7 is a view showing an area of the operation to be effected by the 
doctor or the like standing up at the lateral side of the lower body 40. 
If the height of the lower body 40 is 1,000 mm, the doctor or the like can 
effect the operation in the range of an operation line 202, that is, in 
the range of 600 mm from the doctor or the like. If the height of the 
lower body 40 is about 800 mm, the operation range is increased to the 
range of an operation line 204, that is, in the range of 1,000 mm from the 
doctor or the like. In this embodiment, the height of the lower body 40 is 
in the range of between 600 mm and 750 mm, the operation range is 
increased. In the above embodiment, the hands can reach deeper beyond the 
center of the lower body 40, so that the various operations can be dealt 
with. 
FIG. 8 is a view showing the doctor or the like effecting the operation 
while standing up at the rear side of the lower body 40. If the height of 
the lower body 40 is 1,000 mm, the operation range is in the range of an 
operation line 206, that is, in the range of 600 mm from the doctor or the 
like, as described above for FIG. 7. If the height of the lower body 40 is 
about 800 mm, the operation range is increased to the range of an 
operation line 208, that is, in the range of 1,000 mm from the doctor or 
the like. In this embodiment, the height of the lower body 40 is in the 
range of between 600 mm and 750 mm as explained for FIG. 7, the operation 
can be effected in the range of the operation line 208, that is, in the 
range of 1,000 mm from the doctor or the like. Since the rear side is 
concave inwardly as shown in FIG. 8, the operation range is further 
increased. 
Furthermore, the above L1 is desirable to be made the value between 600 mm 
and 750 mm in case of the patient to be examined lying on the lower body 
for examination and further desirable to be the value between 600 mm and 
800 mm in case of the doctor or the like operating while sitting on a 
chair or standing up. 
And, the above L2 is desirable to be made the value between 400 mm and 435 
mm as a dimension thereof for not reducing an accuracy of the examination 
and in such a manner that the patient to be examined can lie with a space 
on the lower body. Since the accuracy of the examination can be improved 
by setting the height dimension thereof lower value, the L2 is further 
desirable to be made the value between 350 mm and 435 mm. 
Furthermore, the above L3 is most desirable to be made the value between 
950 mm and 1235 mm when the most suitable values of the above L1 and L2 
are taken into consideration. 
FIGS. 9 and 10 show a MRI system according to another embodiment of the 
present invention. A front portion of a lower body 40 is connected to a 
bed 10 in continuous relation thereto. A pair of opposed right and left 
support posts 62 and 64 are provided at the rear side of the lower body 40 
facing away from the bed 10, and the lower body 40 and an upper body 70 
are interconnected by the right and left support posts 62 and 64. The 
lower body 40 and the upper body 70 contain respective opposed magnetic 
poles, inclined magnetic field coils, irradiation coils, receiving coils 
and yokes, as described above in the preceding embodiment. These magnetic 
poles are electromagnetically connected together through a magnetic 
circuit formed in the right and left support posts 62 and 64. Opposite 
lateral sides of the lower body 40 are open, so that the doctors or the 
like can make an examination of the patient, and can apply a necessary 
medical treatment to the patient in a manner as described above in the 
preceding embodiment. The distance between each of the opposite sides of 
the lower body 40 and the center thereof is 750 mm. Preferably, this 
distance is in the range of between 500 mm and 750 mm. With this range, 
the hands can reach the patient from the right, left, front and rear 
sides, so that the medical treatment can be carried out easily. The bed 10 
has a top plate so as to easily move or transfer the patient into the 
lower body 40 as in the preceding embodiment. 
The rear side of this system is also open, and the doctors or the like can 
effect the necessary operation and treatment. In order to make the rear 
side wide open, the distance between the right and left support posts 62 
and 64, that is, between the outer peripheries of the two support posts, 
is set to 1,010 mm. A front portion of the upper body 70 is reduced in 
thickness. This is done not only to reduce the weight of the upper body 70 
but also to reduce the thickness of the front portion of the magnetic pole 
so as to make a magnetic distribution of the magnetic pole generally 
uniform. 
FIG. 11 shows details of an operating portion. Positional deviations, that 
is, deviations in the directions of the width and the height, of the bed 
from the lower body are numerically displayed on a LED display portion 
110. Operation keys 102 are used for operating the bed, and the "LEFT" key 
and "RIGHT" key are used for moving the bed right and left, and when these 
keys are operated, indication elements 127 and 129 are lighted to indicate 
the direction of movement of the bed. When the center of the lower body 
coincides with the centerline of the bed, an indication element 128 is 
lighted. 
When the "UP" key or the "DOWN" key among the operation keys 102 is 
operated, the position of a bed 125 in the LED display with respect to a 
lower body 124 in the LED display in the direction of the height is 
indicated by indication elements 131 and 130. The indication element 130 
is lighted when the height of the bed is generally equal to the height of 
the lower body, whereas the indication element 131 is lighted when the bed 
is at a height lower than the lower body, or the bed is in a downward 
movement mode. 
A key 103 is used for indicating emergency stop of the examination 
operation. Keys 104 are used for turning on an off the light markers and 
for releasing the setting of indication of the reference position. A key 
105 is used for turning on an off the illumination devices. Keys 106 are 
used for controlling the bed so as to move the patient into and out of the 
lower body. A key 107 is an automatic control key for loading and 
unloading the patient. Keys 108 are operation keys for indicating the 
completion of the preparation for the magnetic resonance operation and for 
starting the magnetic resonance operation. The above keys are arranged in 
a predetermined order, and more specifically the operation keys 104 
related to the positioning of the patient, as well as the illumination 
control key 105, are disposed at an upper portion of the operating 
portion, and the bed operating keys 102, 106 and 107 are disposed next to 
these keys, and the magnetic resonance operation and scan keys 108 are 
disposed next to these keys. With respect to the control of the position 
of the bed, the position of the bed with respect to the lower body is 
numerically displayed in a display 120 at the left side portion, and the 
contents of the operation are graphically indicated by the indication 
elements 127, 129 and 131. Therefore, the contents of the operation can be 
confirmed, thus preventing an erroneous operation. 
In the above embodiments, although the right and left support posts 62 and 
64 are offset rearwardly with respect to the center of the lower body 40, 
these support posts 62 and 64 may be offset forwardly toward the bed. In 
this case, when a tebet 11 is brought to the lower body, the sense of 
oppression may slightly increase. However, once it is introduced into the 
measurement space, the degree of opening of the patient's view is 
increased, and therefore the patient feels less oppressed during the 
examination. When the patient requires a medical treatment in addition to 
the examination, necessary instruments can be brought close to the lower 
body from the opposite sides and the rear side, since the rear side is 
wide open during the examination. Therefore, the operation can be carried 
out easily, and the efficiency of the operation is enhanced. 
With the above construction, the doctors or the like can be positioned at 
the opposite (right and left) sides of the lower body, and the examination 
can be effected efficiently, and besides the doctors or the like can 
respond to the patient, and also can apply a necessary medical treatment 
to the patient, using a medical instrument.