MATERIAL AND METHODS |
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| At our institution MR imaging is performed at 1.5-T GE system. We have used EasyVision Release 4.3 (Philips) and 3D package (GE). So far 51 living renal donors have been evaluated. |
The following 16 3D MRI reconstructions have been involved: |
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| 1. MIP (Maximum Intensity Projection): The maximum value encountered on a line through the volume is used on the projection plane. We use the sequence of entire volume MIPs of 360 degrees spin (step 2 degrees) to visualize renal arteries like a conventional angiography (Sequence 1). We use the sequence of depth 10mm slab MIPs of 360 degrees spin (step 2 degrees ) to visualize renal arteries (Sequence 2). We use sequence of depth 10mm oblique & slab (step 1mm) MIPs to visualize renal arteries (Sequence 3). We use sequence of depth 10mm slab MIPs of 360 degrees spin (step 2 degrees ) to visualize renal veins (Sequence 4.). We use sequence of depth 10mm (step 1mm) oblique &slab MIPs to visualize renal veins (Sequence 5). MIP is so quick, easy to use and nice for MR angiography, especially venous anatomy that it has been used as standard reconstruction technique in our study. |
| Sequence 1. entire volume MIP of 360 degrees spin (step 2 degrees ): to visualize four renal arteries. | Sequence 2. depth 10mm slab MIP of 360 degrees spin (step 2 degrees ) to visualize the four renal arteries. | Sequence 3. depth 10mm oblique & slab (step 1mm) MIP to visualize two right renal arteries. |
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| Sequence 4. depth 10mm slab MIP of 360 degrees spin (step 2 degrees ) to visualize renal veins and vena cava. | Sequence 5. depth 10mm (step 1mm) oblique & slab MIP to visualize left renal vein and ovum vein. | |
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2.mIP (Minimum Intensity Projection): the minimum value encountered on a line through the volume is used on the projection plane (sequence 6). We hardly use this technique in our study because of its poor visualization of renal angiography.
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sequence6.mIP 10mm: |
3.Ave (Average intensity projection): the average value of all voxels encountered on a projection ray is used (sequence7). So far we can not find value of the technique in our study.
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sequence7. Ave. |
| 4.CVP (Closest vessel projection): the
value of the first voxels encountered in the volume above a threshold value is used
(sequence 8). So far we can not find value of the technique in our study.
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sequence 8.CVP: |
| 5.Opacity blend (VR-b) weighted average of
voxels: a weighted average is used of voxels encountered on a projection ray (sequence 9).
The classification function defines how the original pixel values are weighted. (Basic
form of volume rending). So far we can not find value of the technique in our study.
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Sequence9. VR-b |
| 6.Planar reformat is used to reconstruct a
single slice in a plane through a volume and displays this slice in the reformat panel
(Figure 1). This plane can be positioned and rotated anywhere in the volume. The technique
is usually helpful in evaluating anatomic relationship of renal arteries and veins
together with kidney lesions in our study since it is quick and easy to use.
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Figure 1. planar
reformat: anatomic relationship between the left renal vein and gonadal vein. |
| 7.Orthogonal reformat is used to reconstruct three slices in mutual orthogonal planes through a volume and displays them simultaneously ( Figure 2.3.4). These planes can be positioned and rotated anywhere in the volume. The technique is helpful in evaluating 3 dimensional anatomy in our study while it is quick and easy to use. |
Figure 2.3.4 Orthogonal reformat: 3 dimensional anatomy of the kidney. |
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| 8.Cross-section reformat is used to show
planes perpendicular to paths in a volume. The cross plane can be stepped along a selected
path to any position on the path (Sequence 10). The technique is sometimes in evaluating
the irregular wall and lumen of vessels in our study while it is time consuming because of
its creating paths.
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Sequence 10:
Cross-section reformat: aorta and renal artery. |
