can ct perfusion evaluate cerebral hemodynamic change in chronic occlusive cerebrovascular diseases?...
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Can CT Perfusion Evaluate Cerebral Hemodynamic Changein Chronic Occlusive Cerebrovascular Diseases?
- Comparison with Diamox-enhanced SPECT -
M. Hirata MD , Y. Sugawara MD , K. Kikuchi MD , H. Miki MD , T. Mochizuki MD , K. Murase PhD , S. Yamauchi RN
INTRODUCTIONCerebral perfusion parameters such as cerebral blood flow
(CBF), cerebral blood volume (CBV), and mean transit time (MTT) are important for the determination of medical treatment plan and/or prognostic prediction of patients with cerebrovascular diseases (CVDs) (1, 2). Although the utilities of CT perfusion in acute stroke have been reported by many investigators (3-6), the role of quantitative CT perfusion parameters in patients with chronic occlusive CVD has not been elucidated enough (7) .
Prior studies from our group and others have shown that CBF and cerebral perfusion reserve (CPR) measurements using Diamox enhancement and SPECT are useful to evaluate hemodynamic status in chronic occlusive CVDs (8, 9).
In this exhibit, we will present the quantitative results of CT perfusion parameters in chronic occlusive CVDs and compare these with the data of Diamox-SPECT. Finally, we will discuss about the advantages and limitations in each of perfusion imaging modalities.
Learning Objectives:
1. Describe the comparative results for quantitative values of CBF, CBV and MTT measured by CT perfusion in comparison with Diamox-enhanced SPECT.
2. Clarify the utilities and limitations in CT perfusion parameters in management of patients with chronic occlusive cerebrovascular diseases.
BACKGROUNDXe-133 SPECT in patients with chronic CVDs
Significantly increased immediately after treatment. Therapeutic effects continue on follow-up
Increased little immediately after PTA and stenting. No significant changes on follow-up
Cerebral Perfusion Reserve
PTA and/or stenting
Cerebral Blood Flow
We previously reported that cerebral perfusion reserve (CPR) significantly increased, but cerebral blood flow increased little immediately after PTA and /or stenting. Therefore, measurement of CPR is useful for evaluating therapeutic effects and for follow-up after PTA and stenting.
Sugawara, et al. (SNM 2000) Hirata , et al. (SNM 2003)
BACKGROUND
• The MTT values in the territories of severely decreased CPR were significantly higher than those in the territories of moderately decreased or normal CPR
• Severe CPR impairment can be estimated with MTT (8).
MR perfusion in patients with chronic CVDs
Perfusion reserve
Severely decreased CPR ≦ 0%
Moderately decreased
0% < CPR ≦ 15%
Normal CPR > 15 %
CBF
CBV
MTT
CBF
CBV
MTT
REST
DIAMOX
42(27%)
Post PTA
MR Perfusion
133Xe-SPECT CT Perfusion
30
1.6
5.4
32
1.6
5.1
29
BACKGROUND
MR Perfusion
CBF
CBV
MTT
REST
DIAMOX
23(-13%)
133Xe-SPECT
Pre PTA
26 Decrease of CPR
Increase of MTT
Improvement of CPR
Normalization of MTT
An example case: 73/M, PTA for Lt. MCA stenosis
Can CT Perfusion Evaluate Cerebral Hemodynamic Changein Chronic Occlusive Cerebrovascular Diseases?
CT perfusion
Mean Transit Time(MTT)
Cerebral Blood Volume(CBV)
Cerebral Blood Flow(CBF)
Diamox-enhanced 133Xe SPECT
Cerebral Perfusion Reserve (CPR)?
relation
Comparison of CBF, CBV and MTT measured by CT perfusion with CPR measured by Diamox-enhanced SPECT
METHODS• CT perfusion protocol
– CT Scanner: Light Speed QX/i (GE) or Ultra (GE)– Dynamic Scan:
• Contrast medium: 300 mgI/ml, total 30-40 ml• 3-4 ml/s with power injector• Cine mode (5mm x 4i, 1 sec/rot) • 5 sec delay for 60 sec
– Data Analysis: Advantage Workstation 4.2 with CT perfusion 3• Xe-133 SPECT protocol
– Xe-133 gas (1850 MBq) inhalation (Kanno-Lassen method)– Dynamic SPECT (20 s/scan x 16, Hitachi SPECT 2000H-40)– At rest and after Diamox® (1g)
• SUBJECTS– 6 male patients with chronic occlusive CVDs
(Mean age = 63.3 ± 9.3 years)Rt. MCA stenosis: 2
Lt. MCA stenosis: 2
Rt.ICA and MCA stenosis with Lt. ICA occlusion: 1
Rt.ICA occlusion : 1
METHODS
MTT
CBV
CBF
CT perfusion
CPR = ×100 (%)CBF(Diamox) - CBF(Rest)
CBF(Rest)
133Xe-SPECT
Mean value inMCA territory
Mean CPR inMCA territory
• Regions of interest were placed in the MCA territories. The values of CBF, CBV and MTT measured by CT perfusion were compared with CPR values obtained from Diamox-enhanced 133Xe-SPECT.
Results -Relation between CPR and CTP parameters-
• Positive correlation was found between CBF and CPR.
• Negative correlation was found between CBV and CPR.
• Negative correlation was found between MTT and CPR.
• The strongest correlation was found in MTT
0
10
20
30
40
50
- 20% 0% 20% 40% 60%CPR
CBF(mL/100g/min)
r = 0.58 CPR
CBV(mL/100 g)
r = -0.34
02468
1012
- 20% 0% 20% 40% 60%CPR
MTT(sec)
r = -0.63
-20 0 20 40 60 (%) -20 0 20 40 60 (%)
-20 0 20 40 60 (%)
• Positive correlation was found between CBF and CPR.
• Negative correlation was found between CBV and CPR.
• Negative correlation was found between MTT and CPR.
• The strongest correlation was found in MTT
REST
DIAMOX
CBF
CBV
MTT
CT Perfusion
41
52(27%)
29
1.7
5.5
19
2.0
10.4
133Xe-SPECT
133Xe-SPECT
REST
DIAMOX
36
32 (-10%)
Case 1: 57/M, Rt. MCA Occlusion
No abnormal findings
CBF ↓CPR ↓
CBF ↓CBV ↑MTT ↑ ↑
Summary 1
• Every CT perfusion parameters correlate with CPR.
• MTT is the most sensitive to reflect severely decreased CPR in chronic occlusive CVDs.
What is the limitation in CT perfusion in management of patients with chronic occlusive cerebrovascular diseases?
Assessment of the therapeutic effects -
Two example cases
CASE 1• STA-MCA anastomasis for Rt. ICA occlusion
CASE 2• CEA for Rt. ICA Stenosis
CASE.1 66/M, STA-MCA anastomasis for Rt. ICA occlusion
REST
Pre STA-MCA
DIAMOX
CBF
CBV
MTT
CT Perfusion
30(0%)
30 35
44(26%)
35
2.9
4.66.2
3.4
27
133Xe-SPECT
REST
Post STA-MCA
DIAMOX
CBF
CBV
MTT
CT Perfusion
39
2.2
4.9
30
3.2
6.8
28
29(4%)
36
39 (6%)
133Xe-SPECT
On CT perfusion•CBF values were decreased.•CBV and MTT values were increased.
On 133Xe-SPECT•CBF and CPR were decreased in Rt. MCA territory.
On 133Xe-SPECT and CT perfusion•No remarkable change was found.
NormalDecrease of Perfusion ReserveMisery PerfusionInfarction
CBF
CBV
MTT
OEF
CMRO2
CASE.1
133Xe-SPECT CT Perfusion
CBF↓ CBF↓
CPR↓ CBV↑
MTT↑
On 133Xe-SPECT, both CBF and CPR were decreased in Rt. MCA territory. This area could be categorized to "misery perfusion" in which CBF is reduced and the oxygen extraction fraction (OEF) is increased to maintain the cerebral metabolic rate of oxygen (CMRO2) (10) .
CT perfusion represented decrease of CBF and increase of CBV and MTT.
On 133Xe-SPECT•CPR increased after treatment. •No remarkable change was found on CBF.
On CT perfusion•No remarkable change was found
on CBF, CBV and MTT.
On 133Xe-SPECT•CPR was decreased in the Rt. MCA territory. •CBF was not decreased.
CASE.2
51(18%)
43(2%)
57(29%)
61 (37%)
CBF
CBV
MTT
CBF
CBV
MTT
Pre CEA Post CEA
REST REST
DIAMOX DIAMOX
45454442
40
2.1
4.7
40
2.1
48
2.3
3.9
43
2.1
4.1
68/M, CEA for Rt. ICA Stenosis
CT Perfusion CT Perfusion133Xe-SPECT 133Xe-SPECT
On CT perfusion•CBF, CBV and MTT were normal.
4.6
NormalDecrease of Perfusion ReserveMisery PerfusionInfarction
CBF
CBV
MTT
OEF
CMRO2
CASE.2
133Xe-SPECT CT Perfusion
CBF → CBF →
CPR ↓ CBV →
MTT →
On 133Xe-SPECT, only CPR was decreased in Rt. MCA territory. In this case, CBF , OEF and CMRO2 were maintained by autoregulatory
vasodilatation (i.e. increase of CBV) (10) .However, all CT perfusion parameters were
normal. This suggest that CT perfusion potentially has limitation in the detection of mild hemodynamic changes.
Summary 2
• Severe ischemic change is detectable by CT perfusion
• CT perfusion potentially has limitation in the detection of mild ischemic changes.
Conclusion
• MTT is the most sensitive to reflect severely decreased CPR in chronic occlusive CVDs.
• CT perfusion potentially has limitation in the detection of mild ischemic changes.
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