Comparing normal values to perfusion values in TIA and ischemic stroke patients

This section presents the results of the fourth study objective: Comparison of normal values to perfusion values of patients with TIA and ischemic stroke.

Special attention should be drawn to the fact that complete hemispheres have been used for the comparison instead of affected flow territories. For example, the comparison using the affected hemispheres of ischemic stroke patients included patients with MCA deficits, patients with PCA deficits and patients with other deficits. A single exception was figure 30, which was created using separated groups for patients with a deficit of the MCA flow territory and patients with a deficit of the posterior flow territory.

The most striking findings in the comparison using the groups that are created according to the affected flow region were the MTT differences within the ischemic stroke group. The MTT was increased in the affected flow region for both the patients with a medial and with a posterior flow deficit, as shown in figure 30.

Comparison to the affected hemisphere of TIA patients

Values of CBF, CBV and MTT for the affected hemisphere of the TIA patients group were derived and presented in table 16. CBF values of grey matter varied between 69 and 110 ml/100g/min with median values between 80 and 91 ml/100g/min. CBF values of white matter varied between 40 and 113 ml/100g/min with median values between 65 and 73 ml/100g/min. No significant CBF differences between the hemispheres of the normal patient group and the affected hemisphere of the TIA patients group were found. CBV values of grey matter varied between 3.7 and 6.2 ml/100g with median values between 4.6 and 5.0 ml/100g. CBV values of white matter varied between 2.2 and 6.1 ml/100g with median values between 3.8 and 4.2 ml/100g. No significant differences with the normal patient group were found. MTT values of grey matter varied between 6.9 and 7.3 s with median values between 7.4 and 7.5 s. MTT values of white matter varied between 7.1 and 9.0 s with median values between 7.6 and 7.8 s. No significant differences with the normal patient group were found.

Table 16. Perfusion values of the affected hemisphere of TIA patients. Values are presented as median (IQR). CBF in ml/100g/min; CBV, ml/100g and MTT, s.

N = 6 Anterior Medial Posterior Basal g.

Grey White Grey White Grey White

CBF 91 (89-94) 65 (54-77) 80 (76-94) 65 (57-83) 90 (82-96) 73 (54-88) 92 (80-100)

CBV 4.9 (4.7-5.4) 3.9 (3.1-5.1) 4.6 (4.1-5.3) 3.8 (3.3-4.8) 5.0 (4.5-5.3) 4.2 (3.1-5.0) 5.0 (4.2-5.7)

72 Figure 30. Boxplots presenting CBF, CBV and MTT obtained from the grey matter of normal subjects, TIA patients and ischemic stroke patients. For the normal subjects boxplots of the medial and posterior flow territories in the right and left hemisphere were included. TIA patients and ischemic stroke patients were divided over a medial and posterior group according to the affected flow territory. In the patient groups the affected flow territory was compared to the contralateral unaffected flow territory. For patients that had a central posterior deficit the mean of the perfusion values of the left and right hemisphere was used and was compared to the unaffected medial flow territory. (eg patients with a basilar artery deficit). Aff indicates affected; Unaff, unaffected.

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Comparison to the affected hemisphere of ischemic stroke patients

Values of CBF, CBV and MTT for the affected hemisphere of the ischemic stroke patients group were derived and presented in table 17. CBF values of grey matter varied between 33 and 151 ml/100g/min with median values between 76 and 88 ml/100g/min. CBF values of white matter varied between 31 and 119 ml/100g/min with median values between 55 and 71 ml/100g/min. No significant CBF differences between the hemispheres of the normal patient group and the affected hemisphere of the TIA patients group were found. CBV values of grey matter varied between 2.1 and 7.0 ml/100g with median values between 4.5 and 4.8 ml/100g. CBV values of white matter varied between 1.9 and 6.8 ml/100g with median values between 3.4 and 4.1 ml/100g. No significant differences with the normal patient group were found. MTT values of grey matter varied between 5.9 and 11.3 s with median values between 7.6 and 7.9 s. MTT values of white matter varied between 7.0 and 10.6 s with median values between 8.0 and 8.2 s. The MTT of grey matter in the medial flow territory showed a significant increase with respect to the MTT of the same region in the right hemisphere of normal subjects; Z = -1.986, p = 0.047. Further, the MTT of white matter in the medial flow territory showed a significant increase with respect to the MTT of the same region in the left hemisphere of normal subjects; Z = -2.013, p = 0.044.

Table 17. Perfusion values of the affected hemisphere of ischemic stroke patients. Values are presented as median (IQR). CBF in ml/100g/min; CBV, ml/100g and MTT, s.

Comparison to the unaffected hemisphere of TIA patients

Values of CBF, CBV and MTT of the unaffected hemisphere of the TIA patients group were derived and presented in table 18. CBF values of grey matter varied between 70 and 111 ml/100g/min with median values between 51 and 84 ml/100g/min. CBF values of white matter varied between 43 and 96 ml/100g/min with median values between 65 and 75 ml/100g/min. No significant CBF differences between the hemispheres of the normal patient group and the affected hemisphere of the TIA patients group were found. CBV values of grey matter varied between 3.9 and 6.2 ml/100g with median values between 4.5 and 4.6 ml/100g. CBV values of white matter varied between 2.5 and 5.5 ml/100g with median values between 3.8 and 4.4 ml/100g. No significant differences with the normal patient group were found. MTT values of grey matter varied between 6.6 and 7.9 s with median values between 7.0 and 7.5 s. MTT values of white matter varied between 7.2 and 8.7 s with median values between 7.6 and 7.9 s. No significant differences with the normal patient group were found.

Table 18. Perfusion values of the unaffected hemisphere of TIA patients. Values are presented as median (IQR). CBF in ml/100g/min; CBV, ml/100g and MTT, s.

N = 29 Anterior Medial Posterior Basal g.

Grey White Grey White Grey White

CBF 78 (66-96) 55 (50-73) 76 (68-90) 61 (54-73) 88 (74-96) 71 (56-83) 90 (81-110)

CBV 4.5 (3.8-5.3) 3.4 (2.8-4.1) 4.5 (4.1-5.1) 3.9 (3.3-4.7) 4.8 (4.5-5.4) 4.1 (3.6-4.9) 51 (47-58)

MTT 7.6 (7.1-8.2) 8.0 (7.6-8.6) 7.9 (7.6-8.4) 8.2 (7.6-9.0) 7.6 (7.3-8.2) 8.1 (7.6-8.5) 7.4 (6.9-7.8)

N = 6 Anterior Medial Posterior Basal g.

Grey White Grey White Grey White

CBF 84 (76-100) 65 (48-86) 83 (74-94) 75 (59-81) 51 (73-86) 71 (67-81) 94 (83-102)

CBV 4.6 (4.0-5.7) 3.8 (2.9-4.7) 4.6 (4.3-5.4) 4.4 (3.3-4.7) 4.5 (4.0-5.0) 4.2 (3.6-4.5) 5.1 (4.6-5.7)

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Comparison to the unaffected hemisphere of ischemic stroke patients

Values of CBF, CBV and MTT of the unaffected hemisphere of the ischemic stroke patients group were derived and presented in table 19. CBF values of grey matter varied between 57 and 137 ml/100g/min with median values between 80 and 87 ml/100g/min. CBF values of white matter varied between 37 and 121 ml/100g/min with median values between 61 and 73 ml/100g/min. No significant CBF differences between the hemispheres of the normal patient group and the affected hemisphere of the TIA patients group were found. CBV values of grey matter varied between 3.2 and 7.3 ml/100g with median values of 4.8 ml/100g. CBV values of white matter varied between 2.4 and 8.0 ml/100g with median values between 3.6 and 4.3 ml/100g. No significant differences with the normal patient group were found. MTT values of grey matter varied between 6.5 and 10.1 s with median values between 7.6 and 7.7 s. MTT values of white matter varied between 6.9 and 9.9 s with median values between 7.8 and 8.0 s. No significant differences with the normal patient group were found.

Table 19. Perfusion values of the unaffected hemisphere of ischemic stroke patients. Values are presented as median (IQR). CBF in ml/100g/min; CBV, ml/100g and MTT, s.