Low-dose cerebral CT perfusion imaging (CTPI) of senile dementia: diagnostic performance

Perfusion CT imaging as a diagnostic and prognostic tool for dementia: prospective case-control study

BACKGROUND

As functional changes precede structural changes in dementia, we aimed to elucidate changes on cerebral perfusion CT (PCT) for early diagnosis of dementia; and to differentiate Alzheimer's disease (AD) from vascular dementia (VaD). We also aimed to study correlation between Montreal Cognitive Assessment (MOCA) score and PCT parameters.

METHODS

We conducted a prospective case-control study enrolling 25 dementia patients (15 cases of VaD, 10 cases of AD) and 25 age-matched controls. PCT was performed on a 256-slice CT scanner. Using perfusion software, colour maps were generated for cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time and time-to-peak. These colour maps were first visually inspected for any abnormalities. Subsequently, quantitative assessment of perfusion parameters was done using symmetrical freehand region of interests drawn in bilateral frontal, temporal, parietal regions, basal ganglia and hippocampi.

RESULTS

Strategic infarcts were present in 93.3% cases and white matter ischaemic changes in 100% cases of VaD. A global reduction in CBF and CBV was also observed in cases of VaD; whereas these parameters were significantly lower mainly in temporoparietal regions and hippocampi of patients with AD. There was significant positive correlation between MOCA score and various perfusion parameters in both forms of dementia.

CONCLUSION

PCT is a reliable imaging modality for early diagnosis of dementia and in differentiating VaD from AD. As perfusion parameters show positive correlation with MOCA score, they could be used as a surrogate marker of cognitive status in the follow-up of patients with dementia.

Adoption of computerized tomography perfusion imaging in the diagnosis of acute cerebral infarct under optimized deconvolution algorithm

Objectives:

To explore the significance of the hemodynamic parameters of Computerized Tomography Perfusion Imaging (CTPI) under the deconvolution optimization algorithm for the diagnosis and treatment of patients with acute cerebral infarct (ACI).

Methods:

A hundred and ten patients with ACI from December 2018 to September 2019 were selected for research, and CTPI was performed before and after Edaravone injection treatment. Then, the CTPI deconvolution algorithm based on the weighted adaptive (WA) total variation (TV) (WA-TV) optimization was constructed, which was compared with tensor total variation (TTV) and Motion-adaptive sparse parity (MASP). Brain Perfusion 4.0 was applied to obtain the relative time to peak (rTTP), the relative transit time of mean (rMTT), relative cerebral blood volume (rCBV), and relative cerebral blood flow (rCBF) of the core infarction area (CIA) and penumbra ischemic (PI).

Results:

In four parameters of rTTP, rMTT, rCBV, and CBF, the peak signal to noise ratio (PSNR) of the WA-TV algorithm was higher than the MSAP and TTV algorithms, while the Mean Square Error (MSE) and Mean Absolute Error (MAE) were lower than MSAP and TTV algorithms (P<0.05); the parameters of rCBV (71.56±9.87), rCBF (43.17±7.06) of the CIA before treatment were higher than PI (23.66±7.22; 18.37±3.99), rMTT (124.83±9.73) and rTTP (122.57±7.41) were lower than the PI (183.17±10.16); 150.74±9.74) (P<0.05). After treatment, the rCBV and rCBF of PI were higher than before treatment, and rMTT and rTTP were lower than before treatment (P<0.05), and there was no obvious difference in rCBV, rCBF, rMTT, and rTTP before and after treatment in the CIA (P>0.05).

Conclusion:

Compared with TTV and MASP, the WA-TV algorithm performs better in noise reduction and artifact reduction. The CTPI parameters of rCBV, rCBF, rMTT, and rTTP are all important indications for the diagnosis of PI and ACI.

The value of whole-brain CT perfusion imaging and CT angiography using a 320-slice CT scanner in the diagnosis of MCI and AD patients

OBJECTIVES

To validate the value of whole-brain computed tomography perfusion (CTP) and CT angiography (CTA) in the diagnosis of mild cognitive impairment (MCI) and Alzheimer's disease (AD).

METHODS

Whole-brain CTP and four-dimensional CT angiography (4D-CTA) images were acquired in 30 MCI, 35 mild AD patients, 35 moderate AD patients, 30 severe AD patients and 50 normal controls (NC). Cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP), and correlation between CTP and 4D-CTA were analysed.

RESULTS

Elevated CBF in the left frontal and temporal cortex was found in MCI compared with the NC group. However, TTP was increased in the left hippocampus in mild AD patients compared with NC. In moderate and severe AD patients, hypoperfusion was found in multiple brain areas compared with NC. Finally, we found that the extent of arterial stenosis was negatively correlated with CBF in partial cerebral cortex and hippocampus, and positively correlated with TTP in these areas of AD and MCI patients.

CONCLUSIONS

Our findings suggest that whole-brain CTP and 4D-CTA could serve as a diagnostic modality in distinguishing MCI and AD, and predicting conversion from MCI based on TTP of left hippocampus.

KEY POINTS

• Whole-brain perfusion using the full 160-mm width of 320 detector rows • Provide clinical experience of 320-row CT in cerebrovascular disorders of Alzheimer's disease • Initial combined 4D CTA-CTP data analysed perfusion and correlated with CT angiography • Whole-brain CTP and 4D-CTA have high value for monitoring MCI to AD progression • TTP in the left hippocampus may predict the transition from MCI to AD.