Purpose
The Penumbra-Effect describes blurring at the margins of an image-profile due to the finite size of the energy source.
A computer aided detection (CAD) algorithm based on the De-convolution Technique (Ref.
1) can be used to pinpoint true-edge positions to sub-pixel accuracy and remove the Penumbra-Effect via sub-pixel transfers without trade-off losses.
Derived from this,
a definitive method of accurate measurement may have been found.
4 case studies of two patients using two MR sequences were used to study the merits of the algorithm and...
Methods and Materials
Composite phantom and New-York Catphan-500 images and 4 case studies were used.
Results
Phantom calibrations: Measurements: Distance & area/volume - At 1% low-contrast:– Distance accurate to 1/50th of a pixel & area/volume accurate to 1/10th of a pixel.
Field-examples:
(1)–(2) 77 year-old patient (7041077) was imaged with MR sequences (i) T2_W_FS+SENSE (SENSE MR breast coil) and (ii) T1_W_3D_FS+GD (Gadolinium contrast injection).
Five consecutive image-slices of each MR sequence across the central breast region (with tumor) were analyzed.
Figure 1 shows the original image of 1,1,2,75 with ROI (Region of Interest) placed over the tumor,
Figure 2 shows the...
Conclusion
Hyper-accurate area and volume measurements of small structures are now possible.
From (1) to (2),
the improvement of 25.42% in the area/volume detection was likely due to the use of Gadolinium contrast agent,
which,
in effect,
improve the contrast-to-noise ratio to detect edges of low-contrast tissues.
Similarly,
an improvement of 49.27% was measured from (3) to (4).
References
(1) "A De-Convolution Technique used for NDT in X-ray & CT",
by Kui M.
Chui,
Shyr L.
Chui,Andrew Wride,
& David B.
Stanfield,
Oral/Full paper presentation in 17th World Conference on Non-destructive Testing (17WCNDT),
Shanghai,
China,
October 25-28,
2008.
(www.NDT.net - The e-Journal & Database of Non-Destructive Testing - ISSN 1435-4934).