| 1. |
- Crafoord, Joakim, et al.
(författare)
-
Comparison of two landmark based image registration methods for use with a body atlas
- 2000
-
Ingår i: Physica medica (Testo stampato). - 1120-1797 .- 1724-191X. ; 16:2, s. 75-82
-
Tidskriftsartikel (refereegranskat)abstract
- We describe preliminary work registering abdominal MRI images from three healthy male volunteers. Anatomically selected 3D homologous point pairs (landmarks), from which eigenvalues were generated to form the basis for a 3D non-affine polynomial transformation, were placed on axial slices alone and on axial, coronal and sagittal slices. Registration accuracy was judged visually by comparing superimposed 3D isosurfaces from the reference, untransformed, and transformed volume data and by comparing merged 2D slices projected fi om the transformed and reference volume data superimposed with 2D isolines. The squared sum of intensity differences between the transformed/untransformed and the reference volume was significant at the 0.05 (p >0.05) confidence level. The correlation coefficient improved by an average of 38% and the cross correlation between pixel values improved by an average of 22%. In each trial, the standard deviation of the landmarks after transformation was within one voxel and the standard error of the mean was not significantly different from zero at the 0.05 confidence level. Abdominal isosurface volume differences (between individuals) changed from an average of 14.5% before registration to 2.9% after registration. This experiment shows that it is possible to choose landmarks such that abdominal data from different subject volumes can be mapped to a common reference, and thus that it is possible to use this combined volume both to form an atlas and to warp abdominal data from an atlas to a patient volume.
|
|
| 2. |
- Kimiaei, Sharok, et al.
(författare)
-
Evaluation of polynomial image deformation using anatomical landmarks for matching of 3D-abdominal MR-images and for atlas construction
- 1999
-
Ingår i: IEEE TRANSACTIONS ON NUCLEAR SCIENCE. - : IEEE. - 0018-9499. ; 46:4, s. 1110-1113
-
Tidskriftsartikel (refereegranskat)abstract
- While a variety of different deformation algorithms have been implemented for matching of skull, few attempts in matching areas in abdomen have been reported. In this study the authors evaluate the usability of first and second order polynomial 3D-warping for this purpose. They match abdominal MR-images from different individuals using manually picked anatomical landmarks. Generation of transformation coefficients was done through a linear regression technique that employs a least square fit using the reference landmarks. The landmarks were picked in a predefined order, well spread over the entire data set, by a radiologist. The image resampling was done using linear interpolation and the evaluation was performed visually as well as by calculating the cross correlation and the normalized least squared error between the original image and the transformed image. The authors' preliminary results reveal that the second order polynomial transformation using landmarks is a robust and efficient method. It is also superior to the second order one, for image deformation in the abdominal region and it may be used in atlas generation as well as in multimodality image co-registration and fusion.
|
|
| 3. |
|
|
| 4. |
- Mahmoud, Faaiza, et al.
(författare)
-
Comparison of three methods for registration of abdominal/pelvic volume data sets from functional-anatomic scans
- 2000
-
Ingår i: SPIE - The International Society for Optical Engineering. - : SPIE - International Society for Optical Engineering. ; , s. 1378-1386
-
Konferensbidrag (refereegranskat)abstract
- The purpose of this work was to evaluate three volumetric registration methods in terms of technique, user-friendliness and time requirements. CT and SPECT data from 11 patients were interactively registered using: a 3D method involving only affine transformation; a mixed 3D - 2D non-affine (warping) method; and a 3D non-affine (warping) method. In the first method representative isosurfaces are generated from the anatomical images. Registration proceeds through translation, rotation, and scaling in all three space variables. Resulting isosurfaces are fused and quantitative measurements are possible. In the second method, the 3D volumes are rendered co-planar by performing an oblique projection. Corresponding landmark pairs are chosen on matching axial slice sets. A polynomial warp is then applied. This method has undergone extensive validation and was used to evaluate the results. The third method employs visualization tools. The data model allows images to be localized within two separate volumes. Landmarks are chosen on separate slices. Polynomial warping coefficients are generated and data points from one volume are moved to the corresponding new positions. The two landmark methods were the least time consuming (10 to 30 minutes from start to finish), but did demand a good knowledge of anatomy. The affine method was tedious and required a fair understanding of 3D geometry.
|
|
| 5. |
- Noz, Marilyn E., et al.
(författare)
-
A versatile functional-anatomic image fusion method for volume data sets
- 2001
-
Ingår i: Journal of medical systems. - 0148-5598 .- 1573-689X. ; 25:5, s. 297-307
-
Tidskriftsartikel (refereegranskat)abstract
- We describe and validate a volumetric three-dimensional registration method, and compare it to our previously validated two-dimensional/three-dimensional method. {CT/MRI} and {SPECT} data from 14 patients were interactively fused using a polynomial warping technique. Registration accuracy was confirmed visually and by a nonsignificant F value from multivariate analysis of the transformed landmarks, a significant difference of the squared sum of intensity differences between the transformed/untransformed and the reference volume both at the 0.05 (p {\textgreater} 0.05) confidence level and an average 31\% improvement of the correlation coefficient and cross correlation. For the two-dimensional/three-dimensional method, {ROI} center-to-center distance ranged from 1.42 to 11.32 mm (for liver) with an average of 6.13 mm +/- 3.09 mm. The average {ROI} overlap was 92.51\% with a 95\% confidence interval of 90.20-96.88\%. The new method is superior because it operates on the true three-dimensional volume. Both methods give good registration results, take 10 to 30 min, and require anatomic knowledge.
|
|
| 6. |
- Noz, Marilyn E., et al.
(författare)
-
Clinical applications from head to toe using a semiautomatic 3D inter/intramodality fusion technique
- 2003
-
Ingår i: BIOMEDICAL IMAGE REGISTRATION. - 3540203435 ; , s. 387-397
-
Konferensbidrag (refereegranskat)abstract
- Automated image registration techniques, particularly between modalities which clearly display anatomy and especially within the head, have become commonplace. Meanwhile advances in molecular imaging and the need to perform registration in other areas of body has driven the development of non-rigid and semiautomatic 3D volume fusion methods. This paper will focus on this latter class of 3D volume registration methods for a variety of clinical applications.
|
|
| 7. |
- Olivecrona, Lotta, et al.
(författare)
-
Acetabular component migration in total hip arthroplasty using CT and a semiautomated program for volume merging
- 2002
-
Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 43:5, s. 517-527
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: To develop a non-invasive method for detection of acetabular cup migration after total hip arthroplasty (THA) with a higher degree of accuracy than routine plain radiography. Material and Methods: Two CT examinations, 10 min apart, were obtained from each of 10 patients that had undergone THA. Using an in-house developed semiautomated program for volume merging, the pelves in the two examinations were fused and the acetabular cup was visually and numerically evaluated to test the method's accuracy in detecting migration. Results: In the visual evaluation of the best match a 1-mm translation of the cup was detectable. The numerical evaluation, comparing landmarks placed in the images of the acetabular cup and the head of the femur component in the two examinations, showed the mean difference in orientation of acetabular axes to be 2.5degrees, the mean distance between centre of cup face to be 2.5 mm and the mean distance between centre of the head of the prosthetic femoral component to be 1 mm. Conclusion: This method has a significantly higher accuracy than routine plain radiography in detecting acetabular cup migration and could be used in clinical practice. It gives both a visual and a numerical correlate to migration.
|
|
| 8. |
- Qatarneh, Sharif M., et al.
(författare)
-
A whole body atlas for segmentation and delineation of organs for radiation therapy planning
- 2001
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - Berlin, Heidelberg : Springer. - 0168-9002 .- 1872-9576. ; 471, s. 160-164, s. 1168-1169
-
Tidskriftsartikel (refereegranskat)abstract
- A semi-automatic procedure for delineation of organs, to be used as the basis of a whole body atlas database for radiation therapy planning was developed. The Visible Human Male Computed Tomography (CT)-data set was used as a standard man reference. The organ of interest was outlined manually and then transformed by a polynomial warping algorithm onto a clinical patient CT. This provided an initial contour, which was then adjusted and refined by the semi-automatic active contour model to find the final organ outline. The liver was used as a test organ for evaluating the performance of the procedure. Liver outlines obtained by the segmentation algorithm on six patients were compared to those manually drawn by, a radiologist. The combination of warping and semi-automatic active contour model generally provided satisfactory segmentation results, but the procedure has to be extended to three dimensions.
|
|
| 9. |
- Qatarneh, Sharif M., et al.
(författare)
-
Evaluation of a segmentation procedure to delineate organs for use in construction of a radiation therapy planning atlas
- 2003
-
Ingår i: International Journal of Medical Informatics. - 1386-5056 .- 1872-8243. ; 69, s. 39-55
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: This paper evaluates a semi-automatic segmentation procedure to enhance utilizing atlas based treatment plans. For this application, it is crucial to provide a collection of 'reference' organs, restorable from the atlas so that they closely match those of the current patient. To enable assembling representative organs, we developed a semiautomatic procedure using an active contour method. Method: The 3D organ volume was identified by defining contours on individual slices. The initial organ contours were matched to patient volume data sets and then superimposed on them. These starting contours were then adjusted and refined to rapidly find the organ outline of the given patient. Performance was evaluated by contouring organs of different size, shape complexity, and proximity to surrounding structures. We used representative organs defined on CT volumes obtained from 12 patients and compared the resulting outlines to those drawn by a radiologist. Results: A strong correlation was found between the area measures of the delineated liver (r = 0.992), lung (r = 0.996) and spinal cord (r = 0.81), obtained by both segmentation techniques. A paired Student's t-test showed no statistical difference between the two techniques regarding the liver and spinal cord (p > 0.05). Conclusion: This method could be used to form 'standard' organs, which would form part of a whole body atlas (WBA) database for radiation treatment plans as well as to match atlas organs to new patient data.
|
|
| 10. |
- Sandgren, Buster, et al.
(författare)
-
Computed Tomography vs. Digital Radiography Assessment for Detection of Osteolysis in Asymptomatic Patients With Uncemented Cups: A Proposal for a New Classification System Based on Computer Tomography.
- 2013
-
Ingår i: The Journal of arthroplasty. - : Elsevier BV. - 1532-8406 .- 0883-5403. ; 28:9, s. 1608-1613
-
Tidskriftsartikel (refereegranskat)abstract
- Digital radiographic images in the anterior-posterior and lateral view have been gold standard for evaluation of peri-acetabular osteolysis for patients with an uncemented hip replacement. We compared digital radiographic images and computer tomography in detection of peri-acetabular osteolysis and devised a classification system based on computer tomography. Digital radiographs were compared with computer tomography on 206 hips, with a mean follow up 10years after surgery. The patients had no clinical signs of osteolysis and none were planned for revision surgery. On digital radiographs, 192 cases had no osteolysis and only 14 cases had osteolysis. When using computer tomography there were 184 cases showing small or large osteolysis and only 22 patients had no osteolysis. A classification system for peri-acetabular osteolysis is proposed based on computer tomography that is easy to use on standard follow up evaluation.
|
|
