Subjects:
16 patients were studied, 9 were males and 7 females, with a mean age of 60 ± 13 years. 14 had SPECT imaging before and after thrombolysis and 2 patients had SPECT imaging only before thrombolysis because their poor clinical outcome did not allow control examination. All patients with anterior circulation ischemia were treated before 6 hours of onset of symptoms while in the posterior circulation the time to treat was variable and depended mostly on the clinical status of the patient. Nine presented with MCA (Middle Cerebral Artery) occlusion, while 4 had basilar artery occlusion and 1 had PCA (Posterior Cerebral Artery) and 2 had carotid artery occlusion. 11 patients presented with right hemisphere lesions and 5 with left hemisphere arterial occlusions. Other variables reported included the NIH scores at admission, discharge, 3 months, Time To Treat (TTT), TIMI recanalization score among others (Please see Table 1).
Table 1
NIH score on admission, on discharge and at three month post Thrombolysis. (Please see Appendix). back
| - |
NIHAdm
|
NIHDisch
|
NIH3ms
|
mR3ms
|
TTT
|
Locat.
|
TIMI
|
| 1 |
17
|
2
|
-
|
-
|
2
|
M1
|
3
|
| 2 |
23
|
11
|
5
|
1
|
4
|
CI/M1
|
3
|
| 3 |
16
|
12
|
8
|
-
|
72
|
Basilar
|
2
|
| 4 |
10
|
1
|
1
|
-
|
1,5
|
M1left
|
2
|
| 5 |
9
|
3
|
0
|
0
|
3
|
M1
|
2
|
| 6 |
18
|
5
|
1
|
2
|
6
|
Basilar
|
3
|
| 7 |
5
|
3
|
2
|
2
|
5
|
P2
|
1
|
| 8 |
4
|
1
|
1
|
-
|
3
|
M1
|
1
|
| 9 |
22
|
10
|
-
|
-
|
3
|
M2
|
3
|
| 10 |
17
|
10
|
8
|
2
|
2,5
|
M1
|
1
|
| 11 |
10
|
23
|
-
|
--
|
-
|
Basilar
|
3
|
| 12 |
14
|
0
|
-
|
0
|
2
|
M2 left
|
2
|
| 13 |
10
|
9
|
7
|
3
|
6
|
M2
|
0
|
| 14 |
14
|
3
|
1
|
0
|
4
|
M1
|
1
|
Imaging Protocol:
Prior to angiography the patient's antecubital vein was cannulated and an HMPAO dose of 30 mCi (1 100 MBq) was administered intravenously. The intravenous injection was given in an approximate volume of 2 ml. followed by a bolus of normal saline of 10 ml. All subjects were maintained in a low ambient light and low noise environment during the intravenous injection and brain uptake phase (2 minutes after injection). After the arterial thrombolysis was completed, imaging of HMPAO distribution in the cerebral cortex was performed utilizing a Dual Head Siemens ECAM SPECT System with Ultra High Resolution collimation and conventional acquisition protocol. The matrix is 64 x 64 with a circular orbit and Step&Shoot motion with 64 steps and 360 degrees rotation. The time of acquisition per projection was 30 seconds with a zoom factor of 1.66 and at the end of acquisition we verified the possibility of a motion artifact in a Cine mode and the Sinogram would demonstrate the existence of patient motion. The subjects laid in supine position, with the head fastened and positioned carefully in order to obtain an optimal orbito-meatal line angle and a vertical midline.
Data analysis:
All studies had the same post acquisition image processing which was performed at Clinica Las Condes. The acquisition was three-dimensionally (3D) reconstructed by back projection by means of a Butterworth filter 4.25 delimiting non-useful information by means of an elliptic region of interest (ROI). We perform oblique reorientation for transaxial, coronal, and sagittal planes with a volume zoom of 35%.
The reconstructed 3D raw images are transferred in an Interfile format to a Personal Computer (PC) in order to reprocess, quantify and normalize their volume.
The computer performed an analysis voxel by voxel of the brain uptake of HMPAO, and the results were normalized and expressed as percentage of maximal uptake observed in the brain for cortical analysis and for basal ganglia analysis. The results were displayed by means of a color scale that defined normal values in a range of 72 ± 5 % of maximum cortical uptake in red color, values above the normal mean above 82%,, in silver color and values below 60% (larger than 2 standard deviations below normal mean) expressed in color yellow, 50% of maximum in color green and below 40% in color blue. Fig.1.
|
Figure 1
|
|
Right MCA Stroke, 53 years old male. Notice extensive and deep hypoperfusion in territory of RMCA. In the projection of temporal lobe there are areas of deep hypoperfusion,< 40 % of maximum in brain cortex. (Color black), with extension into the convexity of parietal lobe. Notice also small focal areas of hypoperfusion in the left hemisphere suggestive of embolism. (Please see Method).
|
automated cortical gray-matter edge detection technique defined 64 ROIs per transaxial image. The data was normalized to the maximal brain activity and the results were expressed as maximal, minimal and average percentage uptake of each ROI. We applied Chang's attenuation correction with an attenuation coefficient µ= 0.1cm-1. Three criticaltransaxial images were analyzed including images located at the orbito-meatal plane and + 70 mm above it and also - 40mm below it. The results were displayed in an Excel table and a program was build to determine areas of interest with Minimal values < 2 standard deviations (SD), < 4 SD and < 8 SD below the mean uptake of HMPAO. Fig. 4.
|
Figure 4
|
|
Transaxial plane same patient, at 3 mm above AC-Post Commissural plane. Edge detection is performed by second derivative analysis and a band with a width of 30% of the distance to the center of the brain is defined. On this band 64 identical size ROIS are automatically determined for quantitative analysis. Maximal, minimal and average activity is reported for each ROI. (Please see Method section). Notice hypoperfusion of Caudate, Lentiforme Nucleus and a segment of Thalamus in Right Hemisphere, denoting ischemia of deep structures. Deepest ischemia appears in the cortex of right frontal-temporal lobes.
|
Furthermore, the Talairach technique normalized the brain volume and allowed a voxel by voxel comparison of the HMPAO uptake in the brain cortex with a normal elderly data base, corrected also volumetrically. In this 3D image, we define a new color scale that represents in color gray values above and below 2 SD of the normal mean, and two standard deviations above the normal mean in color red, also 3 and 4 SD above the normal mean in colors pink and white respectively. Colors light blue, dark blue and green defined areas at 2, 3 and 4 SD below the normal mean (Segami Corp., Maryland, USA). Fig. 2 and 3.
|
Figure 2
|
|
Same study of Figure 1. (Table 1 pt. 1) compared against Normal Older than 45 years Data Base. The territory of right MCA appears with deep hypoperfusion )< 5 SD below the Normal mean (black color). There is a relative small volume of superficial penumbra, color blue 2 and 3 SD below the Normal mean. In the left hemisphere there are small focal areas of superficial hypoperfusion, at 2 SD below the Normal mean.
|
|
Figure 3
|
|
Same study of Figure 1. Color Scale for Deep hypoperfusion, color black = < 8 SD. Demonstrates large area of deep penumbra colors dark blue (4 and 5 SD below Normal) and very deep penumbra color, green (6 and 7 SD below Normal), while there a a peripherical superficial large penumbra color light blue (2 and 3 SD below Normal).
|
Table 2 depicts in column 1 the ROIs that were analyzed in 3 adjacent transaxial images, numbers 0-32 in the right hemisphere progressing counterclockwise from the frontal lobe and numbers 33-64 in the left hemisphere progressing from occipital to frontal lobe.
Statistical analysis of the data: We considered that the absolute SD was a continuous variable, and therefore we applied an unpaired Student t test for the intra-comparison of pairs of before and after thrombolysis in each study group.
