The quantitative potential for breast tomosynthesis imaging.
OBJECTIVE
Due to its limited angular scan range, breast tomosynthesis has lower resolution in the depth direction, which may limit its accuracy in quantifying tissue density. This study assesses the quantitative potential of breast tomosynthesis using relatively simple reconstruction and image processing algorithms. This quantitation could allow improved characterization of lesions as well as image processing to present tomosynthesis images with the familiar appearance of mammography by preserving more low-frequency information.


METHODS
All studies were based on a Siemens prototype MAMMOMAT Novation TOMO breast tomo system with a 45 degrees total angular span. This investigation was performed using both simulations and empirical measurements. Monte Carlo simulations were conducted using the breast tomosynthesis geometry and tissue-equivalent, uniform, voxelized phantoms with cuboid lesions of varying density embedded within. Empirical studies were then performed using tissue-equivalent plastic phantoms which were imaged on the actual prototype system. The material surrounding the lesions was set to either fat-equivalent or glandular-equivalent plastic. From the simulation experiments, the effects of scatter, lesion depth, and background material density were studied. The empirical experiments studied the effects of lesion depth, background material density, x-ray tube energy, and exposure level. Additionally, the proposed analysis methods were independently evaluated using a commercially available QA breast phantom (CIRS Model 11A). All image reconstruction was performed with a filtered backprojection algorithm. Reconstructed voxel values within each slice were corrected to reduce background nonuniformities.


RESULTS
The resulting lesion voxel values varied linearly with known glandular fraction (correlation coefficient R2 > 0.90) under all simulated and empirical conditions, including for the independent tests with the QA phantom. Analysis of variance performed on the fit line parameters revealed statistically significant differences between the two different background materials and between 28 kVp and the remaining energies (26, 30, and 32 kVp) for the dense experimental phantom. How ever, no significant differences arose between different energies for the fatty phantom, nor for any of the many other combinations of parameters.


CONCLUSIONS
These strong linear relationships suggest that breast tomosynthesis image voxel values, after being corrected by our outlined methods, are highly positively correlated with true tissue density. This consistent linearity implies that breast tomosynthesis imaging indeed has potential to be quantitative.
Shafer
Christina M
CM
Department of Radiology, Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705, USA. christina.shafer@duke.edu
Samei
Ehsan
E
Lo
Joseph Y
JY
D000465:Algorithms; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003198:Computer Simulation; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008327:Mammography / Q000295:instrumentation / Q000379:methods*; D008954:Models, Biological; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*
Med Phys. 2008 Feb;35(2):409-11
18383660
Acad Radiol. 2009 Mar;16(3):283-98
19201357
Radiology. 2009 Jul;252(1):40-9
19420321
Radiology. 2008 Mar;246(3):725-33
18195383
JAMA. 2005 Mar 9;293(10):1245-56
15755947
Radiology. 2001 Dec;221(3):657-67
11719660
Med Phys. 1997 Dec;24(12):1863-74
9434969
Med Phys. 2003 Mar;30(3):365-80
12674237
N Engl J Med. 2003 Apr 24;348(17):1672-80
12711743
Phys Med Biol. 1994 Oct;39(10):1629-38
15551535
Phys Med Biol. 2003 Oct 7;48(19):R65-106
14579853
Med Phys. 2005 Dec;32(12):3767-76
16475776
Biometrics. 1949 Jun;5(2):99-114
18151955
Br J Radiol. 2010 Apr;83(988):344-50
19505964
Med Phys. 2002 May;29(5):755-70
12033572
Radiology. 1997 Nov;205(2):399-406
9356620
Ann Intern Med. 2002 Sep 3;137(5 Part 1):344-6
12204019
IEEE Trans Biomed Eng. 1972 Jan;19(1):20-8
5008409