U.S. patent number RE43,499 [Application Number 12/913,372] was granted by the patent office on 2012-07-03 for method to improve cancerous lesion detection sensitivity in a dedicated dual-head scintimammography system.
This patent grant is currently assigned to Jefferson Science Associates, LLC. Invention is credited to Douglas Arthur Kieper, Stanislaw Majewski, Benjamin L. Welch.
United States Patent |
RE43,499 |
Kieper , et al. |
July 3, 2012 |
Method to improve cancerous lesion detection sensitivity in a
dedicated dual-head scintimammography system
Abstract
An improved method for enhancing the contrast between background
and lesion areas of a breast undergoing dual-head
scintimammographic examination comprising: 1) acquiring a pair of
digital images from a pair of small FOV or mini gamma cameras
compressing the breast under examination from opposing sides; 2)
inverting one of the pair of images to align or co-register with
the other of the images to obtain co-registered pixel values; 3)
normalizing the pair of images pixel-by-pixel by dividing pixel
values from each of the two acquired images and the co-registered
image by the average count per pixel in the entire breast area of
the corresponding detector; and 4) multiplying the number of counts
in each pixel by the value obtained in step 3 to produce a
normalization enhanced two dimensional contrast map. This enhanced
(increased contrast) contrast map enhances the visibility of minor
local increases (uptakes) of activity over the background and
therefore improves lesion detection sensitivity, especially of
small lesions.
Inventors: |
Kieper; Douglas Arthur
(Seattle, WA), Majewski; Stanislaw (Morgantown, WV),
Welch; Benjamin L. (Hampton, VA) |
Assignee: |
Jefferson Science Associates,
LLC (Newport News, VA)
|
Family
ID: |
39874360 |
Appl.
No.: |
12/913,372 |
Filed: |
October 27, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
10961552 |
Oct 8, 2004 |
7444009 |
Oct 28, 2008 |
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Current U.S.
Class: |
382/128;
378/37 |
Current CPC
Class: |
G01T
1/1644 (20130101); A61B 6/4258 (20130101); G01T
1/1642 (20130101); A61B 6/583 (20130101); A61B
6/502 (20130101) |
Current International
Class: |
G06K
9/00 (20060101); A61B 6/04 (20060101) |
Field of
Search: |
;382/128,129,130,131,132,133,134 ;378/37,21-27,4,8,901
;600/407,410,411,425,427 ;607/901 ;128/915,916,920,922 ;435/330
;436/64,813 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Majewski et al., "Optimization of Dedicated Scintimammography
Procedure Using Detector Prototypes and Compressible Phantoms,"
IEEE Trans. Nucl. Sci., vol. 48, No. 3, pp. 822-829, Jun. 2001.
cited by other .
Kieper et al., "Improved Lesion Visibility in a Dedicated Dual-Head
Scintimammography System--Phantom Results," submitted for
publication at the 2002 IEEE Medical Imagining Conference, Norfolk,
VA, Nov. 7-19, 2002. cited by other .
Kieper et al., "Optimization of Breast Imaging Procedure with
Dedicated Compact Gamma Cameras," Nuclear Instruments and Methods
in Physics Research, Section A, 497, pp. 168-173, 2003. cited by
other.
|
Primary Examiner: Tabatabai; Abolfazl
Attorney, Agent or Firm: Morgan, Lewis & Bockius LLP
Government Interests
The United States of America may have certain rights to this
invention under Management and Operating Contract No. DE-AC05-84ER
40150 from the Department of Energy.
Claims
What is claimed is:
1. An improved method for enhancing the contrast between background
and lesion areas of a breast undergoing dual-head
scintimammographic examination comprising: 1) acquiring a pair of
digital images from a pair of small FOV or mini gamma cameras
compressing the breast under examination from opposing sides; 2)
inverting one of the pair of images to align or co-register with
the other of the pair of images to obtain a co-registered image and
co-registered pixel values; 3) normalizing the pair of images
pixel-by-pixel by dividing the pixel values from each of the two
acquired images and the co-registered image by the average count
per pixel in the entire breast area of the corresponding detector;
and 4) multiplying the number of counts in each pixel by the value
obtained in step 3 to produce a normalization enhanced two
dimensional contrast map of the breast.
2. The method of claim 1 wherein the breast is directly compressed
by the opposing mini gamma cameras.
.Iadd.3. A method for imaging a breast, comprising: generating
first and second digital images using a pair of opposing small
field of view or mini gamma cameras of a dual-head
scintimammographic imaging system while compressing the breast
under examination from opposing sides; processing the first and
second images to produce first and second processed images having
adjusted pixel values, the processing including: (a) for each of
the first and second images, adjusting the pixel values in the
image based on a value derived from that image, and (b) registering
one of the first and second images to the other of the first and
second images; and generating a combined image derived from
corresponding pixel values from the first and second processed
images. .Iaddend.
.Iadd.4. The method of claim 3, wherein the step of adjusting
comprises: adjusting the pixel values of first image on a
pixel-by-pixel based on a value derived from the pixels of the
first image; and adjusting the pixel values of the second image on
a pixel-by-pixel based on a value derived from the pixels of the
second image. .Iaddend.
.Iadd.5. The method of claim 3, wherein the step of adjusting
comprises: normalizing the pixels values of the first image on a
pixel-by-pixel basis based on a value derived from the pixels of
the first image; and normalizing the pixels values of the second
image on a pixel-by-pixel basis based on a value derived from the
pixels of the second image. .Iaddend.
.Iadd.6. The method of claim 3, wherein the step of adjusting
comprises: normalizing the pixel values of the first image on a
pixel-by-pixel basis by dividing the pixel values from the first
image by the average count per pixel in the entire breast area of
the first image; and normalizing pixels values of the second image
on a pixel-by-pixel basis by dividing the pixel values from the
second image by the average count per pixel in the entire breast
area of the second image. .Iaddend.
.Iadd.7. The method of claim 3, wherein the step of generating the
combined image comprises combining corresponding pixel values of
the first and second processed images on a pixel-by-pixel basis.
.Iaddend.
.Iadd.8. A method for imaging a breast, comprising: generating
first and second digital images using a pair of opposing small
field of view or mini gamma cameras of a dual-head
scintimammographic imaging system while compressing the breast
under examination from opposing sides; processing the first and
second images to produce co-registered first and second processed
images having adjusted pixel values, the processing including
separately altering the pixel values of each of the first and
second images; and generating a combined image derived from
corresponding pixel values from the first and second processed
images. .Iaddend.
.Iadd.9. The method of claim 8, wherein the step of processing
includes registering one of the first and second images to the
other of the first and second images. .Iaddend.
.Iadd.10. The method of claim 8, wherein the step of separately
altering comprises: changing the pixel values of the first image on
a pixel-by-pixel basis based on a value derived from the pixels of
the first image; and changing the pixel values of the second image
on a pixel-by-pixel basis based on a value derived from the pixels
of the second image. .Iaddend.
.Iadd.11. The method of claim 8, wherein the step of processing
includes normalizing the pixel values in each of the first and
second images. .Iaddend.
.Iadd.12. The method of claim 8, wherein the step of generating the
combined image comprises combining corresponding pixel values of
the first and second processed images on a pixel-by-pixel basis.
.Iaddend.
.Iadd.13. A method for imaging a breast, comprising: generating
first and second digital images using a pair of opposing small
field of view or mini gamma cameras of a dual-head
scintimammographic imaging system while compressing the breast
under examination from opposing sides; processing the first and
second images to produce co-registered first and second processed
images, wherein the processing includes calculating, for each pixel
of the first and second image, a corresponding value, the
corresponding value being calculated from a pixel value of the
pixel to which the corresponding value corresponds; and generating
a combined image derived from corresponding pixel values from the
first and second processed images. .Iaddend.
.Iadd.14. A dual-head scintimammographic system for imaging a
breast, comprising: first and second small field of view or mini
gamma cameras, the first and second cameras disposed opposite each
other for generating first and second images of the breast while
compressing the breast under examination; and a computer for
processing the first and second images to produce first and second
processed images having adjusted pixel values and for generating a
combined image derived from corresponding pixel values from the
first and second processed images, wherein the processing includes:
(a) for each of the pair of images, adjusting the pixel values in
the image based on a value derived from that image, and (b)
registering one of the first and second images to the other of the
first and second images. .Iaddend.
.Iadd.15. The dual-head scintimammographic system of claim 14,
wherein the adjusting comprises: adjusting the pixel values of the
first image on a pixel-by-pixel basis based on a value derived from
the pixels of the first image; and adjusting the pixel values of
the second image on a pixel-by-pixel basis based on a value derived
from the pixels of the second image. .Iaddend.
.Iadd.16. The dual-head scintimammographic system of claim 14,
wherein the adjusting comprises: normalizing the pixel values of
the first image on a pixel-by-pixel basis based on a value derived
from the pixels of the first image; and normalizing the pixel
values of the second image on a pixel-by-pixel basis based on a
value derived from the pixels of the second image. .Iaddend.
.Iadd.17. The dual-head scintimammographic system of claim 14,
wherein the adjusting comprises: normalizing the pixel values of
the first image on a pixel-by-pixel basis by dividing the pixel
values from the first image by the average count per pixel in the
entire breast area of the first image; and normalizing the pixel
values of the second image on a pixel-by-pixel basis by dividing
the pixel values from the second image by the average count per
pixel in the entire breast area of the second image. .Iaddend.
.Iadd.18. The dual-head scintimammographic system of claim 14,
wherein generating the combined image comprises combining
corresponding pixel values of the first and second processed images
on a pixel-by-pixel basis. .Iaddend.
.Iadd.19. A dual-head scintimammographic system for imaging a
breast, comprising: first and second small field of view or mini
gamma cameras, the first and second cameras disposed opposite each
other for generating first and second images of the breast while
compressing the breast under examination; and a computer for
processing the first and second images to produce co-registered
first and second processed images having adjusted pixel values and
for generating a combined image derived from corresponding pixel
values from the first and second processed images, wherein the
processing includes separately altering the pixel values of each of
the first and second images. .Iaddend.
.Iadd.20. The dual-head scintimammographic system of claim 19,
wherein the processing includes registering one of the first and
second images to the other of the first and second images.
.Iaddend.
.Iadd.21. The dual-head scintimammographic system of claim 19,
wherein the separately altering comprises: changing the pixel
values of the first image on a pixel-by-pixel basis based on a
value derived from the pixels of the first image; and changing the
pixel values of the second image on a pixel-by-pixel basis based on
a value derived from the pixels of the second image. .Iaddend.
.Iadd.22. The dual-head scintimammographic system of claim 19,
wherein the processing includes normalizing the pixel values in
each of the first and second images. .Iaddend.
.Iadd.23. The dual-head scintimammographic system of claim 19,
wherein generating the combined image comprises combining
corresponding pixel values of the first and second processed images
on a pixel-by-pixel basis. .Iaddend.
.Iadd.24. A dual-head scintimammographic system for imaging a
breast, comprising: first and second small field of view or mini
gamma cameras, the first and second cameras disposed opposite each
other for generating first and second images of the breast while
compressing the breast under examination; and a computer for
processing the first and second images to produce co-registered
first and second processed images and for generating a combined
image derived from corresponding pixel values from the first and
second processed images, wherein the processing includes wherein
calculating, for each pixel of the first and second image, a
corresponding value, the corresponding value being calculated from
a pixel value of the pixel to which the corresponding value
corresponds. .Iaddend.
Description
FIELD OF THE INVENTION
The present invention relates to dual-head scintimammography
techniques for the detection and localization of cancerous lesions
particularly in breast examinations and more particularly to a
method for combining the information provided by the opposing heads
in a dual head system to maximize system sensitivity for cancerous
lesions.
BACKGROUND OF THE INVENTION
Currently scintimammography imaging to detect breast cancer is
performed with standard nuclear medicine cameras and it suffers
from poor sensitivity for lesions under about 1 cm in diameter and
lesions located in the medial aspect of the breast, away from the
large camera surface. The main contributing factor to this poor
performance is the poor spatial resolution during imaging due to
the relatively large distance between the lesion and the collimator
of the detector head.
The development of compact small field of view (FOV)
cameras/detectors, allowed for the placement of the camera directly
against the breast thus significantly minimizing spatial resolution
effects by minimizing the target to collimator distance. Testing
and evaluation of these small FOV cameras in direct contact with
the breast provided the expected increase in detection sensitivity
for small lesions. However it was apparent that lesion-to-camera
distance still had a strong impact upon lesion detection and even
these dedicated instruments can show substantial sensitivity
variation depending on lesion position within the breast. By
incorporating a second camera/detector on the opposite side of the
breast, total target-to-detector distance was further
minimized.
In 2001, Majewski et al. (S. Majewski, E. Curran, C. Keppel, D.
Keiper, B. Kross, A. Pulumbo, V. Popov, A. G. Weisenberger, B.
Welch, R. Wokjcik, M. B. Willimas, A. R. Goods, M. Moore, and G.
Zheng, Optimization of Dedicated Scintimammography Procedure Using
Detector Prototypes and Compressible Phantoms, IEEE Trans. Nucl.
Sci, vol 48, no. 3, pp 822-829, June 2001) proposed a system
implementing two identical and opposed detector heads placed on
either side of a breast under compression to provide an optimal
imaging geometry. While this improved approach confirmed that the
dual head system is especially useful in most clinical situations
where lesion location is not known a priori, the remaining
important issue was how to combine most efficiently the two images
obtained from the double sided imaging.
In a paper published in 2002, Kieper et al. (D. Kieper, S.
Majewski, V. Popov, M. F. Smith, A. G. Weisenberger, B. Welch, R.
Wojcik, M. B. Williams, M. J. Moore, and D. Narayanan, "Improved
Lesion Visibility in a Dedicated Dual-Head Scintimammography
System--Phantom Results", submitted for publication at the 2002
IEEE Medical Imaging Conference, Norfolk, Va., Nov. 7-19, 2002)
further proposed to enhance lesion detection and localization by
enhancing the contrast value through the application of a geometric
mean technique involving the use of the square root of two
registered images, one from each of the two cameras used to
compress the breast from opposing sides. This technique further
enhanced lesion vs. background contrast, but still did not produced
the degree of contrast desired.
Accordingly, there remains a need to further enhance lesion vs.
background contrast to more accurately characterize and localize
potentially cancerous lesions.
OBJECT OF THE INVENTION
It is therefore an object of the present invention to provide a
methodology for the further enhancement of the contrast between
background and lesion areas of a breast undergoing dual-head
scintimammography examination.
SUMMARY OF THE INVENTION
According to the present invention, there is provided an improved
method for enhancing the contrast between background and lesion
areas of a breast undergoing dual-head scintimammographic
examination comprising: 1) acquiring a pair of digital images from
a pair of small FOV or mini gamma cameras compressing the breast
under examination from opposing sides; 2) inverting one of the pair
of images to align or co-register with the other of the images to
obtain co-registered pixel values; 3) normalizing the pair of
images pixel-by-pixel by dividing pixel values from each of the two
acquired images and the co-registered image by the average count
per pixel in the entire breast area of the corresponding detector;
and 4) multiplying the number of counts in each pixel by the value
obtained in step 3 to produce a normalization enhanced two
dimensional contrast map. This enhanced (increased contrast)
contrast map enhances the visibility of minor local increases
(uptakes) of activity over the background and therefore improves
lesion detection sensitivity, especially of small lesions. It also
increases lesion sensitivity independently of lesion position
within the breast volume.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic depiction of the same breast under
compression between two compact gamma camera detector heads.
DETAILED DESCRIPTION
So called mini gamma or small field of view (FOV) cameras and their
methods for use are well known in the art (see for example U.S.
Pat. No. 6,271,525 to Majewski et al. whose description is
incorporated herein by reference in its entirety) and commercially
available from at least two sources: Dilon Technologies, 12050
Jefferson Ave., New Port News, Va. 23606; and Gamma Medica.TM.,
Inc., 19355 Business Center Drive, Suite 8, Northridge, Calif.
91324. Such cameras have been routinely applied to the examination
of breasts for the presence of lesions by a process that involves
injection of the patient with a radiopharmaceutical and examination
of the breast with the mini gamma camera to detect differences in
the uptake of the radiopharmaceutical between normal tissue and
areas containing lesions.
In the 2002 paper by Kieper et al. described above, it was proposed
to enhance lesion detection and localization through the use of a
pair of opposed mini gamma cameras compressing the breast directly
from opposite sides to obtain a pair of images, co-registering the
images and enhancing the contrast value of the co-registered image
through the application of a geometric mean technique involving
taking the square root of two registered images, one from each of
the two cameras used to compress the breast from opposing sides.
While, as stated above, this approached proved highly useful and
did indeed result in enhancement of the images further increase in
contrast between the normal background and lesion areas of the
breast, particularly in the detection of small lesions, <about 1
cm, was desired.
We have now discovered a better method for combining the
information provided by the opposing detector heads as proposed by
Kieper et al. to maximize system sensitivity for cancerous
lesions.
In accordance with the present invention, the breast tissue 10 is
first compressed between two opposing, mini gamma camera detector
heads 12 and 14 including collimators 13 and 15 and gamma
transparent faces 17 and 19 as shown in FIG. 1, preferably in the
absence of additional passive compression paddles. This compression
geometry maximizes the spatial resolution by minimizing the average
detector-to-lesion distance as discussed above, and minimizes the
absorption and scatter effect of radiation emitted by the lesion
by, on average, decreasing the amount of benign tissue between the
lesion and the detector heads. Additionally, it minimizes the
thickness of overlaying breast tissue to be imaged and therefore
enhances lesion contrast by minimizing background emitted by that
benign tissue. This technique is described in detail in the
aforementioned Kieper et al. paper that is also incorporated herein
by reference in its entirety.
The imaging process of the present invention differs from that of
Kieper et al. in it use of a novel image normalization/fusion
technique that provides a two dimensional contrast map of the
breast that is the result of multiplying the normalized pixel
values of each of the two images together. The advantages of the
use of the method of the present invention will be clearly
demonstrated by a direct comparison of the results of contrast maps
obtained by the method of Kieper et al. and that of the instantly
described method.
In order to demonstrate the enhanced results of the method of the
present invention over those of Keiper et al., the methodology of
Kieper et al. was replicated. A compressible breast phantom was
constructed from gelatin filler mixed with Tc-99 sodium
pertecnitate in solution encapsulated in a latex outer skin to
simulate breast tissue. Three plastic lesion spheres were filled
with a specific activity six times greater than that of the gelatin
mix and then introduced into the breast phantom as shown at 16, 18
and 20 in FIG. 1. The left lesion (16 in FIG. 1) had a diameter of
0.6 cm the center lesion (18 in FIG. 1) a diameter of 0.8 cm and
the left lesion (20 in FIG. 1) a diameter of 0.45 cm. The exact
method of preparing flexible gelatin breast phantoms is well known
in the art and is described in detail in the following paper, S.
Majewski, E. Curran, C. Kepple, D. Keiper, B. Kross, A. Pulumbo, V.
Popov, A. G. Weisenberger, B. Welch, Wojcik. M. B. Williams, A. R.
Goode, G. Moore, and G. Zang, "Optimization of Dedicated
Scintimamography Procedure Using Detector Prototypes and
Compressible Phantoms", IEEE Trans. Nucl. Sci. 2001, 48(3):
822-829, which paper is incorporated herein in its entirety for its
description of the method of preparing gelatin based breast
phantoms. The breast phantom containing the inserted "lesions" was
then compressed to 6 cm +/-1.5 cm between two opposing mini gamma
cameras as shown in FIG. 1. This experimental set up is identical
to that used by Keiper et al. As reported by Keiper et al.,
contrast results for each of the three lesions and the combined
image results obtained using the geometric mean technique, square
root (image 1* and image 2) are as shown in Table 1 below.
TABLE-US-00001 TABLE 1 Left lesion Center Lesion Right Lesion 0.6
cm dia. 0.8 cm dia. 0.45 cm dia. Detector 1 1.25 1.28 1.07 Detector
2 1.11 1.31 1.04 Combined 1.38 1.69 1.13 Image
In contrast to the above results when the identical opposed, dual
camera, compression experimental arrangement (as shown in Figure)
was used but the contrast was enhanced using the image
normalization/fusion technique of the present invention, the
results were as shown in Table 2 below.
TABLE-US-00002 TABLE 2 Left lesion Center Lesion Right Lesion 0.6
cm dia. 0.8 cm dia. 0.45 cm dia. Detector 1 1.73 1.65 1.39 Detector
2 1.95 1.61 1.16 Combined 3.38 2.68 1.61 Image
In the tests performed in accordance with the present invention,
the positions of cameras 12 and 14 were geometrically aligned to
better than 1 mm so as to achieve a one-to-one pixel
correspondence. In the first step, the image from second camera 14,
initially vertically mirror-reflected relative to first camera
position 12, was inverted to align (co-register) with the first
image obtained from first camera 12. Using the average count per
pixel in the entire breast area of the corresponding detector as a
normalization value, the number of counts in each pixel was divided
by that normalization value. Thus, pixel values at or near
background level became equal to a value near one while any
meaningful lesion signal produced normalized pixel values greater
than one. The normalized images from each detector were then
multiplied pixel-by-pixel to combine and "magnify" the presence of
co-registered focal hot spots. As shown above, the use of this
technique indeed enhanced the visibility of the small lesions.
There has thus been described a method for enhancing the
sensitivity of scintimammographic images to the presence of
especially small lesions in a dual-head/opposing view mini gamma
camera system. The availability of such enhanced sensitivity will
further increase the diagnostician's ability to identify and locate
ever smaller potentially cancerous lesions at ever earlier time
thereby advancing the start of remedial treatment.
As the invention has been described, it will be apparent to those
skilled in the art that the same may be varied in many ways without
departing from the intended spirit and scope of the invention, and
any and all such modifications are intended to be included within
the scope of the appended claims.
* * * * *