Positioning in magnetic resonance imaging

In magnetic resonance imaging, prepared first is a three-dimensional image data consisting of a plurality of tomographic image data of a diagnostic portion of an object being examined. Then, data of a pilot image in the three-dimensional image data are designated, and the pilot image is displayed. Then, a linear ROI (region of interest) is placed on the displayed pilot image. Then, image data of a cross-section are edited from the three-dimensional image data, the cross-section passing through the linear ROI in a space of the three-dimensional image data. On the basis of the edited image data of the cross-section, a prediction image for scan is displayed.

BACKGROUND OF THE INVENTION 
The present invention relates to a positioning technique in magnetic 
resonance imaging, and in particular, to the positioning technique 
applying multiplanar reconstruction (MPR) to a three-dimensional image 
data composed of a plurality of tomographic images collected at different 
slice positions of an object being diagnosed. 
In magnetic resonance imaging, an object to be diagnosed is placed in a 
static magnetic field, whereby atomic nuclei align themselves with the 
static magnetic field. Then gradient magnetic fields in three x-, y- and 
z-directions are applied to the object for spatially encoding and a radio 
frequency (RF) signal is applied to the object for exciting the atomic 
nuclei in a magnetically sliced plane, which has a certain thickness in a 
slicing direction, of the object. When the RF signal is removed, magnetic 
resonance (MR) signals emitted from the sliced plane can be collected. A 
series of the excitation and MR signal acquisition is performed on a 
predetermined pulse sequence. The collected MR signals are then processed, 
for example, by Fourier transformation to form image data of the 
magnetically sliced plane of the object. 
Prior to the scan for diagnosis, it is usual to perform a preparation which 
includes a process of positioning. There are two ways for the positioning; 
one way is to use a light localizer, and another way is to use one or two 
pilot images. 
In positioning with a single pilot image, as shown in FIG. 1, a single 
tomographic image IMi (for instance, an axial image of an object) is given 
as a single pilot image. On the pilot image IMi, a linear ROI(region of 
interest) Ra is placed to specify an arbitrary linear position thereon, 
thus specifying a slice plane perpendicular to the pilot image IMi at its 
linear position specified by the ROI Ra. Slice positions to be scanned are 
determined such that they are parallel to the specified slice plane. As a 
result, a scan for diagnosis is carried out at the determined slice 
positions. Hereinafter, the term "linear ROI" is used for specifying a 
linear position, so this includes line ROIs and elongated rectangular 
ROIs. 
On one hand, in positioning with two pilot images, as shown in FIG. 2, the 
first and second tomographic images IMi and IMj (for instance, both are 
axial images parallel to each other) are given as two pilot images. Then, 
one linear ROI Rb is placed on the first pilot image IMi and another 
linear ROI Rc is placed on the second pilot image IMj. In consequence, a 
slice plane passing through the two linear ROIs Rb and Rc at the same time 
can be specified for a scan. Using the two parallel pilot images enables 
positioning in any direction. 
However, it is impossible for the above positioning ways with one and two 
pilot images to provide an entire tomographic image of a slice plane to be 
scanned before the diagnostic scan. Hence, there is no means for 
operators, such as doctors, who place the above linear ROIs to Judge 
whether or not the slice plane determined by the ROIs catches properly a 
desired lesion to be examined. In other words, for images except one or 
two pilot images, operators have to place one or two ROIs with his or her 
intuition or presumption. 
Therefore, improper positioning situations have often been occurred; for 
example, the position of a lesion is different or deviates from a desired 
slice plane, for which a diagnostic scan will be carried out. In such 
cases, most of the images finally obtained will be useless and it is 
required to repeat the same process of positioning. This results in 
reduced efficiency of diagnostic throughput. 
Further, operators are necessarily required to have a skilled technique and 
much experience for placing ROIs. So the positioning operation becomes a 
hard work. 
Still further, although the slice position to be scanned can be shown by 
the two ROIs on the two pilot images, the slice angle of a slice plane are 
not easily recognizable thereon. As a result, it is difficult to designate 
a proper slice plane having a desired slice angle. 
SUMMARY OF THE INVENTION 
Accordingly, it is a primary object of the present invention to provide a 
positioning technique by which a slice image in a diagnostic scan can be 
confirmed before an actual diagnostic scan and a slice position can surely 
be arranged. 
It is a further object of the present invention to provide a positioning 
technique to be able to perform precise and easy-to-operate positioning, 
thus preventing efficiency of diagnosis from being reduced. 
It is a further object of the present invention to provide a positioning 
technique decreasing a volume of data calculation than in case that a 
prepared three-dimensional image data is directly processed. 
It is a still further object of the present invention to provide a 
positioning technique by which a slice angle is easily recognizable. 
These and other objects can be achieved according to the present invention, 
in one aspect by providing, a method of magnetic resonance imaging 
comprising steps of: a step of preparing a three-dimensional image data 
consisting of a plurality of tomographic image data of a diagnostic 
portion of an object being examined; a step of designating data of a pilot 
image in the three-dimensional image data; a step of displaying the pilot 
image; a step of placing a linear region of interest on the displayed 
pilot image; a step of editing image data of a cross-section from the 
three-dimensional image data, the cross-section passing through the linear 
region of interest in a space of the three-dimensional image data; and a 
step of displaying a prediction image for scan on the basis of the edited 
image data of the cross-section. 
Further, by providing a method of magnetic resonance imaging comprising 
steps of: a step of preparing a three-dimensional image data consisting of 
a plurality of tomographic image data of a diagnostic portion of an object 
being examined; a step of designating data of a pilot image in the 
three-dimensional image data; a step of displaying the pilot image; a step 
of placing a first linear region of interest on the displayed pilot image; 
a step of editing image data of a first cross-section from the 
three-dimensional image data, the first cross-section passing through the 
first linear region of interest and being perpendicular to the pilot image 
in a space of the three-dimensional image data; a step of displaying a 
reference image on the basis of the image data of the first cross-section; 
a step of placing a second linear region of interest on the displayed 
reference image; a step of editing image data of a second cross-section 
from the three-dimensional image data, the second cross-section passing 
through the second linear region of interest in a space of the 
three-dimensional image data; and a step of displaying a prediction image 
for scan on the basis of the edited image data of the second 
cross-section. 
Preferably, the pilot image consists of one image and the reference image 
consists of one image and said first and second linear regions of interest 
consist of one region of interest, respectively. 
It is also preferred that the pilot image consists of one image and the 
reference image consists of two images, the first linear region of 
interest consists of two regions of interest placed on the one pilot 
image, and the second linear region of interest consists of two regions of 
interest placed on the two reference images, respectively. The two first 
linear regions of interest are parallel to each other on the pilot image 
and the two second linear regions of interest are parallel to each other 
over the two reference images. 
It is also preferred that the step of editing image data of a second 
cross-section has a step of judging whether or not the second 
cross-section is twisted and a step of stopping the editing of the image 
data when the second cross-section is twisted. 
It is preferred to further comprise a step of judging whether or not said 
prediction image is desired in response to a signal supplied for the 
prediction image. It is also preferred to further comprise steps of: a 
step of performing a scan plan on the basis of the prediction image, when 
the prediction image is desired; and a step of performing said scan in 
accordance with the scan plan. 
Still further, by providing a method of magnetic resonance imaging 
comprising steps of: a step of preparing a three-dimensional image data 
consisting of a plurality of tomographic image data of a diagnostic 
portion of an object being examined; a step of designating data of a pilot 
image in the three-dimensional image data; a step of displaying the pilot 
image; a step of placing a two-dimensional data collecting area on the 
displayed pilot image; a step of placing a linear region of interest on 
the displayed pilot image, the linear region of interest passing through 
the two-dimensional data collecting area; a step of editing image data of 
a cross-section from the three-dimensional image data, the cross-section 
passing through the linear region of interest and being perpendicular to 
the pilot image in a space of the three-dimensional image data; a step of 
displaying a reference image on the basis of the image data of the 
cross-section; and a step of specifying a one-dimensional data collecting 
range on the displayed reference image, the one-dimensional data 
collecting range, together with the two-dimensional data collecting area, 
determining a three-dimensional voxel size for local excitation in 
spectroscopy. 
In another aspect by providing, a system for magnetic resonance imaging 
comprising: an element for preparing a three-dimensional image data 
consisting of a plurality of tomographic image data of a diagnostic 
portion of an object being examined; an element for designating data of a 
pilot image in the three-dimensional image data; an element for displaying 
the pilot image; an element for placing a linear region of interest on the 
displayed pilot image; an element for editing image data of a 
cross-section from the three-dimensional image data, the cross-section 
passing through the linear region of interest in a space of the 
three-dimensional image data; and an element for displaying a prediction 
image for scan on the basis of the edited image data of the cross-section. 
Further, by providing, a system for magnetic resonance imaging comprising: 
an element for preparing a three-dimensional image data consisting of a 
plurality of tomographic image data of a diagnostic portion of an object 
being examined; an element for designating data of a pilot image in the 
three-dimensional image data; a first element for displaying the pilot 
image; a first element for placing a first linear region of interest on 
the displayed pilot image; a first element for editing image data of a 
first cross-section from the three-dimensional image data, the first 
cross-section passing through the first linear region of interest and 
being perpendicular to the pilot image in a space of the three-dimensional 
image data; a second element for displaying a reference image on the basis 
of the image data of the first cross-section; a second element for placing 
a second linear region of interest on the displayed reference image; a 
second element for editing image data of a second cross-section from the 
three-dimensional image data, the second cross-section passing through the 
second linear region of interest in a space of the three-dimensional image 
data; and a third element for displaying a prediction image for scan on 
the basis of the edited image data of the second cross-section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Embodiments of the present invention will now be described with reference 
to the accompanying drawings. 
A first embodiment of the present invention will now be described according 
to FIGS. 3 to 8. FIG. 3 is a block diagram schematically representing the 
whole construction of an MRI system of the first embodiment. 
The MRI system shown in FIG. 3 comprises a magnet 1 generally formed into a 
cylinder shape having a hollow portion therein for placing a patient P, 
and a static power source 2 for supplying required electric current to the 
magnet 1. When the magnet 1 begins to work, a static field, having a 
uniform magnetic strength H.sub.0 and being directed in Z-direction along 
the body axis of the patient P, is formed in the central diagnostic space 
in the hollow portion of the magnet 1. 
In the hollow portion of the magnet 1, there is provided a gradient coil 
portion 3. The gradient coil portion 3 includes two pairs of x-coils 3x . 
. . 3x for generating a field gradient in X-direction, two pairs of 
y-coils 3y . . . 3y for generating a field gradient in Y-direction, and 
one pair of z-coils 3z and 3z for generating a field gradient in 
Z-direction. 
An RF coil 4 is disposed in the inner space of the magnet 1, whereby the 
patient P inserted into the inner space is surrounded by the RF coil 4 and 
the gradient coils 3x . . . 3z. The RF coil 4 is in charge of transmitting 
and receiving radio frequency(RF) magnetic pulses to and from the patient 
P. 
The MRI system is also provided with a main controller 10 controlling the 
entire system, a gradient sequence controller 11 controlling the pulse 
sequences to the field gradients, an RF sequence controller 12 controlling 
the pulse sequence to the RF signal. The main controller 10 comprises a 
computer for entire control of the entire system. The main controller 10 
is able to send a start signal and a stop signal of the pulse sequences to 
the controllers 11 and 12. 
The gradient sequence controller 11 is also provided with a computer which 
stores programs of pulse sequences including a multi-slice and a gradient 
field echo process, for example. In response to the start signal from the 
main controller 10, the gradient sequence controller 11 is to supply 
pulsed currents to the x-coils 3x . . . 3x, y-coils 3y . . . 3y, and 
z-coils 3z and 3z, respectively, according to a given sequence. 
As shown in FIG. 3, the RF sequence controller 12 is connected to the RF 
coil 4 by way of a transmitter 20 and a receiver 21. The transmitter 20 is 
designed to supply a radio frequency(RF) pulsed current to the RF coil 4, 
thus a high frequency magnetic field generated from the RF coil 4 being 
sent to a diagnostic portion of the patient P. MR signals emitted from the 
diagnostic portion of the patient P can be detected by the RF coil 4 and 
received by the receiver 21 through control of the RF sequence controller 
12. 
The received MR signals are sent, by way of an analogue to digital 
converter 24, to a data calculator 25 to be reconstructed therein into 
corresponding image data with Fourier transformation, for example. The 
image data thus-reconstructed is designed to be stored in a data memory 
unit 26. 
The main controller 10 is also connected to an input device 27, a program 
memory unit 28, and a display unit 29. The reconstructed image data can be 
supplied, through the main controller 10, to the display unit 29. The 
program memory unit 28 stores a procedure from positioning to scanning 
shown in FIG. 4. This procedure is to be taken into a work area of the 
main controller 10, when the present MRI system is started. 
The entire operation of this embodiment will now be explained using FIGS. 4 
to 7. 
After the arrangement and registration of a patient, the procedure shown in 
FIG. 4 will be started by the main controller 10. 
At Step 20 in FIG. 4, a command of multi-slice imaging is sent to the 
gradient and RF sequence controllers 11 and 12. The multi-slice imaging 
slices a portion containing a lesion at its plural but adjacent slice 
positions, thus providing a three-dimensional image data of a plurality of 
tomographic images IM1 to IMn for positioning, as shown in FIG. 5. 
Then at Step 21, among the plurality of images IM1 to IMi, a single 
tomographic image IMi is designated as a pilot image for the positioning. 
This designation is done in response to either an image position command 
from a operator through the input device 27 or a predetermined 
automatically-generated command therein. As a result, for example, a 
tomographic image at the front is designated as a pilot image. 
Then at Step 22, the pilot image IMi thus-designated is displayed on the 
display unit 29 as shown in FIG. 6A, for instance. 
At Step 23, by way of the input device 27, the operator places two linear 
ROIs Rd and Re at desired positions on the displayed pilot image IMi, as 
shown in FIG. 6B. The two linear ROIs Rd and Re compose first linear ROIs 
of the present invention. In this embodiment, while one ROI Rd specifies a 
cross-section in the transverse direction of the pilot image IMi in FIG. 
6B, the other ROI Re specifies a cross-section in the longitudinal 
direction perpendicular to the transverse direction. As another variation, 
it is possible to place the two ROIs Rd and Re obliquely crossed with each 
other. 
Then the process at Step 24 will be carried out. Namely, two 
cross-sections, passing through each of the linear positions of the two 
ROIs Rd and Re and being perpendicular to the pilot image IMi, are 
estimated. Image data of pixels composing the two cross-sections are each 
edited (i.e., searched and gathered) from the three-dimensional image 
data. 
At Step 25, in divided form shown in FIG. 6C, the image data of the two 
perpendicular cross-sections edited at Step 24 are displayed on the 
display unit 29 as a transverse cross-section image IMx and a longitudinal 
cross-section image IMy, the both images IMx and IMy corresponding to 
reference images of the present invention. 
At the next Step 26, as illustrated in FIG. 6D, elongated rectangular ROIs 
Rf and Rg are each manually placed by the operator on the transverse and 
longitudinal cross-section images IMx and IMy. In this situation, the 
operator can observe carefully the cross-section images IMx and IMy, and 
select the positions for the elongated rectangular ROIs Rf and Rg such 
that a cross-section passing through the ROIs Rf and Rg becomes a desired 
slice plane to be scanned. 
After the placing of the ROIs Rf and Rg, which correspond to second linear 
ROIs of the present invention, Step 27 is processed. At this Step 27, it 
is judged whether or not the cross-section passing through the two ROIs Rf 
and Rg is twisted. If Yes (twisted), the procedure of Step 28 will be 
done. That is, it is displayed that the editing of image data for the 
cross-section passing through the two ROIs Rf and Rg is impossible, 
because of the twist of the cross-section. In this situation, the 
processing will be returned to Step 26 for resetting the elongated 
rectangular ROIs Rf and Rg. 
In contrast, when No at Step 27 (not twisted), the processing will go on to 
Steps 29 to 31. 
At Step 29, one cross-section, passing through the linear positions of the 
two ROIs Rf and Rg at the same time, is estimated. Image data of pixels 
composing the cross-section is edited also from the three-dimensional 
image data. For example, in case of the two oblique ROIs Rf and Rg 
illustrated in FIG. 6D, the cross-section passing the ROIs Rf and Rg 
becomes an oblique slice plane shown in FIG. 7, the oblique slice plane 
slicing the head of a patient obliquely in both front-to-back and 
left-to-right directions with no twist. Therefore, proper selection of the 
angles of the two ROIs Rf and Rg enables the specification of any slice 
plane having an arbitrary slice angle and having no twist, in addition to 
axial, sagittal and coronal images. 
Then at Step 30, the image data thus-edited at Step 29 is displayed, as a 
prediction image IMob, on the display unit 29, as shown in FIG. 6E by 
divided form. That is, even if a diagnostic scan has not been carried out 
yet, the monitor of the display unit 29 provides the prediction image 
IMob, which is a tomographic image edited from the three-dimensional data 
in positioning. For example, when the oblique cross-section shown in FIG. 
7 is specified by the ROIs Rf and Rg, the prediction image IMob is its 
tomographic image. 
Hence, the prediction image IMob have a meaning that when a diagnostic scan 
will is carried out, the resultant reconstructed image is approximately 
like so, thus providing the operator an appropriate scan image beforehand. 
As the prediction image IMob is created by editing from the 
three-dimensional image date once reconstructed, it is true that the 
prediction image IMob is lower in diagnostic information values than the 
original three-dimensional image date. But still, the prediction image 
IMob maintains configuration information with high accuracy, besides 
information of a slice angle. 
Then at Step 31, the operator Judges whether or not the prediction image 
IMob is acceptable for a diagnostic scan carried out later on. When 
acceptable (YES), at Step 32, a desired scan plan is done using 
information (such as a slice angle and a position of a lesion) obtained 
from the prediction image IMob. 
Finally, at Step 33, under the scan plan including a given pulse sequence, 
a scan for diagnostic is carried out, thereby providing reconstructed 
images of a lesion of the patient. 
If the prediction image IMob is not satisfied (NO), the processing will be 
returned to Step 21 for resetting of it. 
As mentioned above, the MRI system of the present invention utilizes a 
technique of multiplanar reconstruction (MPR) and provides a tomographic 
image as a prediction image of a cross-section along which a diagnostic 
scan is to be carried out. An operator can confirm the prediction image by 
direct observation beforehand. It is not required to position a slice 
plane to be scanned on the basis of operator's intuition or estimation, 
thus leading to steadier positioning. 
In consequence, errors in positioning are reduced substantially than the 
conventional positioning technique, with the result that higher quality 
images can be obtained through the scan. 
In addition, according to this embodiment, when a prediction image IMob 
displayed once is not satisfied for an operator, it can easily be 
re-displayed through the resetting of ROIs. Operation skill is relieved 
greatly and positioning operation is greatly facilitated. These lead to 
increased throughput in diagnosis. 
Furthermore, because the present invention uses two-dimensional images as a 
pilot image and reference images in a three-dimensional image, it is easy 
for an operator to access the three-dimensional image data. Also, 
calculation load for data processing is rather reduced, compared with a 
data processing technique handling a three-dimensional image data 
directly. 
The functional block of the MRI system in accordance with the present 
embodiment can be illustrated as shown in FIG. 8. The processing of Step 
20 in FIG. 4 composes the main part of an image data preparation means. 
Also, Step 21 composes the main part of a pilot image designation means, 
Step 22 composes the main part of a first display means, and Step 23 
composes the main part of a first ROI placing means. Moreover, Step 24, 25 
and 26 are included into a first image data editing means, a second 
display means and a second ROI placing means, respectively. Further, Step 
27 corresponds a twist judging means. Steps 29 and 30 compose the main 
parts of a second image data editing means and a third display means, 
respectively. Still further, Step 31 composes a judging means. Steps 32 is 
included in a scan plan means and Step 33 is included in a scanning means. 
In the first embodiment, judgement for the pilot image and/or the reference 
images, that is, question steps asking if they are desired or not can be 
inserted between Steps 22 and 23 and/or between Steps 25 and 26 in FIG. 4. 
A second embodiment of the present invention will now be described 
according to FIGS. 9 and 10. The hardware construction of an MRI system in 
this embodiment is the same as that in the first embodiment, except that 
the positioning process carried out by the main controller 10. The same or 
equivalent hardware components use the same reference numerals as the 
first embodiment. This usage of the reference numerals are applied to all 
of the following embodiments. 
The second embodiment uses a way in which the judgement of the twist for 
the final cross-section is not required, instead of adding some 
restrictions to the placing of the ROIs in the first embodiment. 
FIG. 9 shows a procedure from positioning to scanning in the second 
embodiment carried out by the main controller 10. 
Steps 40 to 42 in FIG. 9, which are carried out in turn, are the same as 
Steps 20 to 22 in FIG. 4. This leads to the display of a one pilot image 
IMi (for example, an axial image of a head shown in FIG. 10A), which is 
one of the three-dimensional image data IM1 to IMn. 
Then at Step 43, it is judged whether or not the pilot image IMi is proper 
and acceptable, on the basis of signals through the input device 27 from 
an operator. If NO (another pilot image is desired), the processing will 
be returned to Step 41 for resetting. If YES (pilot image now on display 
is acceptable), the processing of Steps 44 to 46 will be done as follows. 
At Step 44, in response to ROI designation signals from the operator, two 
elongated and rectangular first ROIs R1a and R1b are placed in parallel on 
desired positions on the pilot image IMi. For example, as shown in FIG. 
10B, the ROIs R1a and R1b are placed such that on the pilot image they are 
oblique and parallel to each other. These first ROIs R1a and R1b 
correspond to first linear ROIs of the present invention. 
At Step 45, in the same way as Step 24 in FIG. 4, image data of two 
cross-sections, perpendicular to the pilot image IMi at the positions of 
the ROIs R1a and R1b, are edited from the three-dimensional image data. At 
Step 46, as illustrated in FIG. 10C, the image data of the two 
cross-sections thus edited are displayed as two reference images IMa and 
IMb, respectively. In case of FIG. 10C, the reference images IMa and IMb 
are tomographic images sliced along longitudinal directions of a head at 
the positions of the ROIs R1a and R1b. 
Then at Step 47, it is judged whether the reference images IMa and IMb are 
acceptable. As a result, when NO (not acceptable) comes out thereat, the 
processing is to be returned to Step 44 for resetting of the first ROIs 
R1a and R1b. In contrast, when YES (acceptable) comes out, Steps 48 to 50 
will proceed. 
At Step 48, as exemplified in FIG. 10D, two elongated and rectangular 
second ROIs R2a and R2b are each placed in parallel on desired positions 
on the two reference images IMa and IMb, the reference images IMa and IMb 
being displayed on condition that their directions are aligned in the same 
direction. These second ROIs R2a and R2b correspond to second linear-ROIs 
of the present invention. 
Steps 49 and 50 is the same as Steps 29 and 30, thus editing image data of 
a cross-section passing through the two ROIs R2a and R2b and displaying a 
prediction image IMob, as shown in FIG. 10E, using the edited image data. 
Namely, on top of axial, sagittal and coronal images, an oblique 
prediction image IMob having an arbitrary slice angle can be displayed. 
Further, at Step 51, it is Judged if the prediction image IMob is 
acceptable or not. If another prediction image IMob is desired (NO), the 
processing will then be returned to Step 48. Contrary to it, the 
prediction image IMob is acceptable (YES), Steps 52 and 53 will be done in 
the same way as Steps 32 and 33 in FIG. 4, with the result that a scan 
plan and a diagnostic scan are carried out. 
As apparent from the above, the second embodiment can offer almost the same 
advantages as the first embodiment. Besides, as each pair of the first and 
second ROIs R1a, R1b and R2a, R2b are placed in parallel to each other, 
the judgement of twist of the final cross-section is not required, 
resulting in much simplified processing. Moreover, on the way to the scan 
plan, three judgements (refer to Steps 43, 47 and 51) are inserted and the 
operator are asked if the pilot image IMi, the reference images IMa and 
IMb, and the prediction image IMob is acceptable or not at each stage. 
This gives a steady positioning operation at each stage and can shorten 
the whole operation time when the final prediction image IMob is not 
acceptable, compared with the first embodiment. 
In the second embodiment, the judgement of Steps 43 and/or 47 in FIG. 9 can 
be omitted, if necessary. 
A third embodiment of the present invention will now be described according 
to FIGS. 11 and 12. 
In the third embodiment, the number of the first ROI and the second ROI is 
reduced to one, respectively. 
FIG. 11 shows a procedure from positioning to scanning in the third 
embodiment carried out by the main controller 10. Steps 60 to 63 in FIG. 
11 are the same as Steps 40 to 43 in FIG. 9. As a result, a pilot image 
IMi (for example, an axial image of a head) is displayed on the display 
unit 29, as shown in FIG. 12A. 
Then at Step 64, a single elongated rectangular first ROI R1 (corresponding 
to a first linear ROI of the present invention) is placed at a desired 
position on the pilot image IMi, as shown in FIG. 12B. At Step 65, image 
data of a cross-section passing through the first ROI R1 and being 
perpendicular to the pilot image IMi are edited from the three-dimensional 
image data. At Step 66, the image data of the perpendicular cross-section 
thus-edited are displayed as a single reference image IMref, as 
illustrated in FIG. 12C. 
Then at Step 67, it is Judged whether or not the reference image IMref is 
acceptable. When not accepted (NO), the processing will be returned to 
Step 64. When accepted (YES), Step 68 will be carried out such that, as 
shown in FIG. 12D, a single elongated rectangular second ROI R2 
(corresponding to a second linear ROI of the present invention) is placed 
at a desired position on the reference image IMref. Also at Step 68, image 
data of a cross-section passing through the second ROI R2 and being 
perpendicular to the reference image IMref are edited from the 
three-dimensional image data. At Step 70, the image data of the 
perpendicular cross-section thus-edited are displayed as a prediction 
image IMob, as illustrated in FIG. 12E. The prediction image IMob can give 
any oblique tomographic image, besides axial, sagittal and coronal images. 
In addition, Steps 71 to 73, the same as Steps 51 to 53 in FIG. 9, is 
carried out in turn. 
Because the first and second ROIs are each one, ROI placing operation and 
data processing are simplified. Further, the prediction image is also 
reduced in number than the first and second embodiments, but still 
maintains enough tomographic information to diagnostic scan. Still 
further, the three confirmations (refer to Steps 63, 67 and 71) gives a 
steady positioning operation. 
A fourth embodiment of the present invention will now be described 
according to FIGS. 13 to 15. 
In the fourth embodiment, the positioning is reduced to one process stage. 
FIG. 13 shows a procedure from positioning to scanning in the fourth 
embodiment carried out by the main controller 10. Steps 80 to 85 in FIG. 
13 are the same as Steps 60 to 65 in FIG. 11. As a result, a single ROI R1 
is placed on a pilot image IMi as shown in FIGS. 14A and 14B, and image 
data of a cross-section passing through the ROI R1 and being perpendicular 
to the pilot image IMi are edited. 
Then at Step 86, the image data of the cross-section are displayed as a 
prediction image IMob, as shown in FIG. 14C. Then Steps 87 to 89 is 
processed in the same way as Steps 71 to 73 in FIG. 11. 
The fourth embodiment is able to obtain a prediction image without a 
reference image. The process to obtain the prediction image is shortened 
to only one stage, so the processing for data editing is simplified. 
In this embodiment, as shown in FIG. 15, Step 80 in FIG. 13 composes the 
main part of an image data preparation means of the present invention. 
Also, Step 81 composes the main part of a pilot image designation means 
and Step 82 does the main part of a pilot image display means. Further 
Step 84 is included in a ROI placing means. Steps 85 and 86 are included 
in an image data editing means and a prediction image display means, 
respectively. Furthermore, Step 87 corresponds to a judging means. Step 88 
composes a part of a scan plan means and Step 89 composes a part of a 
scanning means. 
A fifth embodiment of the present invention will now be described according 
to FIGS. 16 and 17. 
In the fifth embodiment, the positioning still consists of one stage, but 
two pilot images are used therein. 
FIG. 16 shows a procedure from positioning to scanning in the fifth 
embodiment carried out by the main controller 10. At Step 90 in FIG. 16, a 
three-dimensional image data of a lesion is collected. Then at Step 91, 
among a plurality of tomographic images IM1 to IMn composing a 
three-dimensional image data, two desired tomographic image IMi and IMj 
are designated as two pilot images. For example, the two pilot images IMi 
and IMj are the images at the front and back of the three-dimensional 
image data. 
The two pilot images IMi and IMj thus designated are displayed, as shown in 
FIG. 17A. At Step 93, it is judged if these pilot images IMi and IMj are 
acceptable. 
After the pilot images IMi and IMj have been confirmed, at Step 94, two 
elongated rectangular ROIs R1a and R1b are placed on them, respectively, 
as shown in FIG. 17B. At this time, the two ROIs R1a and R1b are placed in 
parallel to each other. Then at Step 95, image data of a cross-section 
passing through the two ROIs R1a and R1b are edited from the 
three-dimensional image data. Further, at Step 96, the image data 
thus-edited are displayed as a prediction image IMob, as shown in FIG. 
17C. 
Then Steps 97 to 99 are processed in the same way. 
This embodiment is able to predict an arbitrary oblique tomographic image, 
except that images in the same direction as the pilot images. Moreover, as 
the pilot image is increased in number than the fourth embodiment, more 
information of tomographic images is obtained with simplified one-stage 
processing, leading to more precise positioning. 
A sixth embodiment of the present invention will now be described according 
to FIGS. 18 and 19. 
The sixth embodiment relates to collection of voxel data in spectroscopy. A 
data collection by local excitation in spectroscopy have been done using 
an ISIS (image-selected in vivospectroscopy) method, for instance. This 
data collection adopts a positioning technique in which one pilot image is 
prepared and a rectangular ROI is placed on the pilot image for specifying 
a two-dimensional collection area. In addition to the collection area, 
under a conventional manner, a collection range in the depth direction of 
a lesion was given by manual operation. These collection area and range 
determines a three-dimensional voxel size for excitation. 
In the above conventional manner, the collection range in the depth 
direction relied largely upon the sense of an operator. This sometimes 
resulted in the exclusion of a necessary important part of a lesion or the 
inclusion of a unnecessary part of it. That is, it is difficult to 
adequately determine the voxel size, thus often leading to recollection 
and increased collection time as a whole. 
FIG. 18 shows a procedure from positioning to scanning in the sixth 
embodiment carried out by the main controller 10. 
Steps 100 to 103 in FIG. 18 are the same as the aforementioned embodiments, 
with the result that one pilot image IMi (e.g. an axial image of a head) 
is displayed as in FIG. 19A. 
The pilot image IMi is confirmed at Step 103. Then at Step 104, a 
rectangular ROI Rrec is placed on the pilot image IMi, as shown in FIG. 
19B, for specifying a two-dimensional collection area. 
Further at Step 105, a linear ROI Rn, such as a line ROI and an elongated 
rectangular ROI, is placed in a manner that it passes the rectangular ROI 
Rrec (refer to FIG. 19C-1 or 19C-2). The linear ROI Rn may be set in any 
direction. Then at Step 106, image data of a cross-section passing the 
linear ROI Rn and being perpendicular to the pilot image IMi are edited as 
well, and at Step 107, the image data edited is displayed as a reference 
image IMtm, as shown in FIG. 19D-1 or 19D-2). 
At Step 108, it is judged if the reference image IMtm is desired one. When 
NO (not desired image), the processing will go back to Step 105. In 
contrast, when YES (desired image), Step 109 is processed, in which two 
ROIs are used to specify a collection range in the depth direction on the 
reference image IMtm. For the specification, for example, two line ROIs 
Rm1 and Rm2 can be used to limit the collection range to a certain and 
appropriate one as shown in FIG. 19E-1 or two point ROIs Rs1 and Rs2 can 
also be used as shown in FIG. 19E-2. 
Using the collection area and range thus-specified, a scan plan is done at 
Step 110. And at Step 111, data collection by local excitation is carried 
out, for instance, with an ISIS method. 
As apparent from the above, the present invention can be applied to the 
data collection by local excitation in spectroscopy, preventing the 
collection range in the depth direction from being specified by the sense 
of an operator. This surely leads to more precise and proper determination 
of the voxel size. As a result, the present embodiment is effective in 
avoiding useless repeat of scans and excessive collection time.