scholarly journals Intraoperative Imaging of Cortical Blood Flow by Camera-Based Photoplethysmography at Green Light

2020 ◽  
Vol 10 (18) ◽  
pp. 6192
Author(s):  
Oleg V. Mamontov ◽  
Anton V. Shcherbinin ◽  
Roman V. Romashko ◽  
Alexei A. Kamshilin
Keyword(s):  
Blood Flow ◽  
Pulse Shape ◽  
Arrival Time ◽  
Surgical Intervention ◽  
Green Light ◽  
Blood Perfusion ◽  
Pulse Arrival Time ◽  
Cortical Blood Flow ◽  
Pulse Arrival ◽  
The Brain

Intraoperative evaluation of blood perfusion in the brain cortex is an important but hitherto unresolved problem. Our aim was to demonstrate the feasibility of cerebral microcirculation assessment during open brain surgery by using camera-based photoplethysmography (cbPPG) synchronized with an electrocardiograph. Cortical blood flow was monitored in five patients with different diagnoses. Two cases (tumor resection and extra-intracranial bypass grafting) are presented in detail. Blood-flow parameters were visualized after processing cortex images recorded under green-light illumination before and after surgical intervention. In all cases, blood flow was successfully visualized in >95% of open brain. Distributions of blood pulsation amplitude, a parameter related to cortical blood perfusion; pulse arrival time; and blood-pressure-pulse shape were calculated with high spatial resolution (in every pixel). Changes in cerebral blood supply caused by surgical intervention were clearly revealed. We have shown that the temporal spread of pulse arrival time and the spatiotemporal variability of pulse shape are very sensitive markers of brain circulatory disturbances. The green-light cbPPG system offers a new approach to objective assessment of blood-flow changes in the brain during surgical intervention. The proposed system allows for contactless monitoring of cortex blood flow in real time with high resolution, thus providing useful information for surgery optimization and minimization of brain tissue damage.

Pulsar Timing Observations at Tidbinbilla

1976 ◽  
Vol 3 (1) ◽  
pp. 81-83 ◽  
Author(s):  
R. N. Manchester ◽  
W. M. Goss ◽  
Lynette M. Newton ◽  
P. A. Hamilton
Keyword(s):  
Faraday Rotation ◽  
High Frequency ◽  
Pulse Shape ◽  
Arrival Time ◽  
Dispersion Measure ◽  
Pulse Arrival Time ◽  
Pulsar Timing ◽  
One Year ◽  
Pulse Arrival

Pulse arrival time measurements allow the determination of accurate pulsar periods, period derivatives and, provided the data span is at least one year, precise pulsar positions. If observations are frequent and reasonably regular, irregularities in the period can also be investigated. To minimize the effect of possible variations in dispersion measure, it is important that these observations be made at a relatively high frequency, preferably above 1 GHz. To eliminate pulse shape variations due to variable ionospheric Faraday rotation, the pulse total intensity or one of the circular polarizations must be recorded.

Pulse Arrival Time Techniques

2019 ◽  
pp. 43-59
Author(s):  
Marshal S. Dhillon ◽  
Matthew J. Banet
Keyword(s):  
Arrival Time ◽  
Pulse Arrival Time ◽  
Pulse Arrival

Vascular pressures and cortical blood flow in cavernous angioma of the brain

1990 ◽  
Vol 73 (4) ◽  
pp. 555-559 ◽  
Author(s):  
John R. Little ◽  
Issam A. Awad ◽  
Stephen C. Jones ◽  
Zeyd Y. Ebrahim
Keyword(s):  
Blood Flow ◽  
Cavernous Angioma ◽  
Sitting Position ◽  
Cortical Blood Flow ◽  
Content Type ◽  
Cavernous Angiomas ◽  
Arterial Blood ◽  
Mean Pressure ◽  
Local Cortical Blood Flow ◽  
The Brain

✓ This study was designed to investigate the hemodynamic characteristics of cavernous angiomas of the brain. Five adult patients with a cavernous angioma underwent local cortical blood flow studies and vascular pressure measurements during surgery for the excision of the cavernous angioma. Clinical presentation included headache in four patients, seizures in four patients, and recurring diplopia in one patient. Magnetic resonance imaging demonstrated the cavernous angiomas in all patients and revealed an associated small hematoma in two. Four patients with a cerebral cavernous angioma were operated on in the supine position and the remaining patient, whose lesion involved the brain stem, was operated on in the sitting position. Mean local cortical blood flow (± standard error of the mean) in the cerebral cortex adjacent to the lesion was 60.5 ± 8.3 ml/100 gm/min at a mean PaCO2 of 35.0 ± 0.6 torr. Mean CO2 reactivity was 1.1 ± 0.2 ml/100 gm/min/torr. The local cortical blood flow results were similar to established normal control findings. Mean pressure within the lesion in the patients undergoing surgery while supine was 38.2 ± 0.5 mm Hg; a slight decline in cavernous angioma pressure occurred with a drop in mean systemic arterial blood pressure and PaCO2. Mean pressure in the cavernous angioma in the patient operated on in the sitting position was 7 mm Hg. Jugular compression resulted in a 9-mm Hg rise in cavernous angioma pressure in one supine patient but no change in the patient in the sitting position. Direct microscopic observation revealed slow circulation within the lesions. The hemodynamic features demonstrated in this study indicate that cavernous angiomas are relatively passive vascular anomalies that are unlikely to produce ischemia in adjacent brain. Frank hemorrhage would be expected to be self-limiting because of relatively low driving pressures.

The Effect of Peripheral Pulse Arrival Time(PPAT) Measurement in Evaluating Endothelial Function: a Comparison with Flow-Mediated Vasodilation(FMD)

2004 ◽  
Vol 34 (2) ◽  
pp. 178
Author(s):  
Moo Hyun Kim ◽  
Dong Sung Kum ◽  
Suk Hwan Chung ◽  
Seung Ho Han ◽  
Tae Hyung Lim ◽  
...  
Keyword(s):  
Endothelial Function ◽  
Arrival Time ◽  
Pulse Arrival Time ◽  
Peripheral Pulse ◽  
Flow Mediated Vasodilation ◽  
Pulse Arrival

A computational model for blood perfusion in ischemic strokes

2020 ◽  
Vol 31 (05) ◽  
pp. 2050064
Author(s):  
Lanhua Zhang ◽  
Tao Wang ◽  
Mingfeng Yang ◽  
Shaowei Xue ◽  
Yujuan Li ◽  
...  
Keyword(s):  
Blood Flow ◽  
Ischemic Stroke ◽  
Computational Model ◽  
Correlation Matrix ◽  
Network Modeling ◽  
Small World ◽  
Blood Perfusion ◽  
And Topology ◽  
Vessel Injury ◽  
The Brain

Quantitative analysis is vital for blood perfusion in ischemic stroke validating and predicting blood trend to refer and remedy on selection, operation and intervention. We leveraged the complex network modeling blood perfusion to pursue the changes and trends of blood flow in ischemic stroke. According to conversion of the flow chart from laser Doppler perfusion images of rats into the correlation matrix, the blood perfusion networks were formed and topology characters were quantitatively analyzed. The results verified the steal phenomenon and the compensatory ability in the vessel injury in accord with clinical indexes by the basic characters and efficiency, especially the interesting local efficiency. In addition, the outcomes exhibited consistently the small-world characters in the brain of rats. This computational model strengthened the new way of blood perfusion and potential predictions for stroke’s assessment, operation and prevention from the basic vascular dynamic indexes and complex networks.

Evaluation of blood pressure estimation models based on pulse arrival time

2020 ◽  
Vol 84 ◽  
pp. 106616
Author(s):  
José M. Bote ◽  
Joaquín Recas ◽  
Román Hermida
Keyword(s):  
Blood Pressure ◽  
Arrival Time ◽  
Pulse Arrival Time ◽  
Pressure Estimation ◽  
Blood Pressure Estimation ◽  
Pulse Arrival ◽  
Estimation Models
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