scholarly journals Validity of the γ-Ray Evaluation with iodoamphetamine for Cerebral Blood Flow Assessment (REICA) method for quantification of cerebral blood flow including acetazolamide challenge test

2022 ◽  
Author(s):  
Yoshiaki Miyazaki ◽  
Masashi Kameyama ◽  
Akira Nakamizo ◽  
Tomoyuki Noguchi ◽  
Nobuyuki Tabata
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Challenge Test ◽  
Correlation Coefficients ◽  
Flow Quantification ◽  
Emission Computed Tomography ◽  
Arterial Blood ◽  
Significant Difference ◽  
Γ Ray ◽  
Acetazolamide Challenge

Abstract Objective The γ-Ray Evaluation with iodoamphetamine for Cerebral Blood Flow Assessment (REICA) is a new method for quantifying cerebral blood flow (CBF) using single-photon emission computed tomography (SPECT) and [123I]N-isopropyl-p-iodoamphetamine (123I-IMP). The present study aimed to validate the REICA method using data including acetazolamide challenge test. Methods The REICA and Graph-Plot (GP) methods were used to calculate mean CBF (mCBF) for 92 acquisitions (rest: 57, stress: 35) and cerebrovascular reactivity (CVR) in 33 patients. To obtain stress data, 15 mg/kg of acetazolamide was injected intravenously 10 min before the administration of 123I-IMP, and blood samples were collected under the same conditions as rest data. The reference standard was the Autoradiograph (ARG) method using arterial blood sampling, and the accuracy of the REICA method was analyzed by comparing it with each method. Results For mCBF, the correlation coefficients (r) were 0.792 for the REICA method and 0.636 for the GP method. For CVR, r values were 0.660 for the REICA method and 0.578 for the GP method. In both acquisitions, the REICA method had a stronger correlation with the ARG method than the GP method. For mCBF, there was a significant difference in the correlation coefficient between the two correlation coefficients (p < 0.01). Conclusions The REICA method was more accurate than the GP method in quantifying CBF and closer to the ARG method. The REICA method, which is a noninvasive method of cerebral blood flow quantification using 123I-IMP, has great medical usefulness.

Reduced regional cerebral blood flow measured by 99mTc-HMPAO SPECT in microgravity simulated by 5-day dry immersion

2021 ◽  
Author(s):  
Laurent Guillon ◽  
Marc Kermorgant ◽  
Thomas Charvolin ◽  
Fabrice Bonneville ◽  
Marie-Pierre Bareille ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Regional Cerebral Blood Flow ◽  
Peak Level ◽  
Emission Computed Tomography ◽  
Regional Cerebral Blood ◽  
Caudate Nuclei ◽  
Dry Immersion ◽  
Hmpao Spect ◽  
Significant Difference

Abstract Purpose Neuro-ophthalmological changes defined as spaceflight-associated neuro-ocular syndrome have been reported after long duration space flights. The pathophysiology of this syndrome remains unclear, with the possible involvement of elevated intracranial pressure. Changes in blood flow in the brain, evaluated indirectly by Doppler, have been reported in flight. However, the effects of microgravity on regional cerebral blood flow (rCBF) are not known. We therefore investigated changes in rCBF in a 5-day dry immersion (DI) model. Moreover, we tested thigh cuffs as a countermeasure to prevent potential microgravity-induced modifications in rCBF.Methods 18 healthy male participants underwent 5-day DI with or without a thigh cuffs countermeasure. They were randomly allocated to a control (n = 9) or cuffs (n = 9) group. rCBF was measured 4 days before DI (Pre-DI) and at the end of the fifth day of DI (Post-DI), using single-photon emission computed tomography (SPECT) with radiopharmaceutical 99mTc-hexamethyl propylene amine oxime (HMPAO). SPECT images were processed using statistical parametric mapping (SPM12) software.Results At DI5, we observed a significant decrease in rCBF in 32 cortical and subcortical patterns, with greater hypoperfusion in the occipital region (occipital peak level: z = 4.51, puncorr < 0.001) and basal ganglia (putamen peak level: z = 4.71, puncorr < 0.001; caudate nuclei peak level: z = 3.80, puncorr < 0.001). No significant difference was found between the control and cuffs groups on variations in rCBF at DI5.Conclusion 5-day DI induces a relative decrease in rCBF in cortical and subcortical regions. Nevertheless, the consequences of this decrease for brain function and mechanisms need further investigation.

scholarly journals Reproducibility of Cerebral Blood Flow Assessment using a Quantitative SPECT Reconstruction Program and Split-Dose 123I-Iodoamphetamine in Institutions with Different γ-Cameras and Collimators

2012 ◽  
Vol 32 (9) ◽  
pp. 1757-1764 ◽  
Author(s):  
Hiroshi Yoneda ◽  
Satoshi Shirao ◽  
Hiroyasu Koizumi ◽  
Fumiaki Oka ◽  
Hideyuki Ishihara ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Vascular Reactivity ◽  
Single Photon ◽  
Photon Emission ◽  
Emission Computed Tomography ◽  
Multicenter Studies ◽  
Quantitative Spect ◽  
Split Dose ◽  
Acetazolamide Challenge

Single photon emission computed tomography (SPECT) is used widely in clinical studies. However, the technique requires image reconstruction and the methods for correcting scattered radiation and absorption are not standardized among SPECT procedures. Therefore, quantitation of cerebral blood flow (CBF) may not be constant across SPECT models. The quantitative SPECT (QSPECT) software package has been developed for standardization of CBF. Using the QSPECT/dual-table autoradiographic (DTARG) method, CBF and cerebral vascular reactivity (CVR) at rest and after acetazolamide challenge can be evaluated using 123I-iodoamphetamine in a single SPECT session. In this study, we examined the reproducibility of quantitative regional CBF and CVR in QSPECT/DTARG using different SPECT models at two facilities. The subjects were nine patients with chronic cerebral ischemic disease who underwent QSPECT/DTARG at both facilities with use of different γ-cameras and collimators. There were significant correlations for CBF at rest and after acetazolamide challenge measured at the two facilities. The consistency of the CBFs of the patients measured at the two facilities were good in all cases. Our results show that CBF measured by QSPECT/DTARG in the same patients is reproducible in different SPECT models. This indicates that standardized evaluation of CBF can be performed in large multicenter studies.

scholarly journals Cerebrovascular Carbon Dioxide Reactivity in Sheep: Effect of Propofol or Isoflurane Anaesthesia

2002 ◽  
Vol 30 (4) ◽  
pp. 413-421 ◽  
Author(s):  
J. A. Myburgh ◽  
R. N. Upton ◽  
G. L. Ludbrook ◽  
A. Martinez ◽  
C. Grant
Keyword(s):  
Carbon Dioxide ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Linear Regression Analysis ◽  
Published Data ◽  
Anaesthetic Agents ◽  
Sagittal Sinus ◽  
Doppler Probe ◽  
Arterial Blood ◽  
Significant Difference

Propofol and isoflurane are commonly used in neuroanaesthesia. Some published data suggest that the use of these agents is associated with impaired cerebral blood flow/carbon dioxide (CO 2 ) reactivity. Cerebrovascular CO 2 reactivity was therefore measured in three cohorts of adult merino sheep: awake (n=6), anaesthetized with steady-state propofol (15 mg/min; n=6) and anaesthetized with 2% isoflurane (n=6). Changes in cerebral blood flow were measured continuously from changes in velocities of blood in the sagittal sinus via a Doppler probe. Alterations in the partial pressure of carbon dioxide in arterial blood (P a CO 2 ) over the range 18–63 mmHg were achieved by altering either the inspired CO 2 concentration or the rate of mechanical ventilation. Cerebral blood flow/CO 2 relationships were determined by linear regression analysis, with changes in cerebral blood flow expressed as a percentage of the value for a P a CO 2 of 35 mmHg. Propofol decreased cerebral blood flow by 55% relative to pre-anaesthesia values (P=0.0001), while isoflurane did not significantly alter cerebral blood flow (88.45% of baseline, P=0.39). Significant linear relationships between cerebral blood flow and CO 2 tension were determined in all individual studies (r 2 ranged from 0.72 to 0.99). The slopes of the lines were highly variable between individuals for the awake cohort (mean 4.73, 1.42–7.12, 95% CI). The slopes for the propofol (mean 2.67, 2.06–3.28, 95% CI) and isoflurane (mean 2.82, 2.19–3.45, 95% CI) cohorts were more predictable. However, there was no significant difference between these anaesthetic agents with respect to the CO 2 reactivity of cerebral blood flow.

Drug Effects on Cerebral Blood Flow in the Baboon Model - Acetazolamide and Nimodipine

1993 ◽  
Vol 32 (06) ◽  
pp. 292-298 ◽  
Author(s):  
D. W. Oliver ◽  
I. F. Redelinghuys ◽  
N. Hugo ◽  
G. Beverley ◽  
I. C. Dormehl
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Single Photon ◽  
Photon Emission ◽  
Drug Effects ◽  
Emission Computed Tomography ◽  
Arterial Blood ◽  
Baboon Model ◽  
The Individual

SummaryThe sensitivity of the baboon model under anaesthesia for single photon emission computed tomography (SPECT) of the brain with 99mTc-HMPAO, as recently developed by us to study cerebral blood flow patterns, was investigated using drugs that are known to increase cerebral blood flow, e.g. acetazolamide, the carbonic anhydrase inhibitor and nimodipine, the calcium channel blocker. Increases in cerebral blood flow for both acetazolamide and nimodipine were observed that correspond well with other studies. Statistically significant regional specificity was noted for acetazolamide and nimodipine. Interestingly a combination of these drugs did not enhance cerebral blood flow but rather decreased it in comparison with the individual drug responses. The results were correlated with arterial blood pressure, heart rate, pCO2 and pO2. A blood pressure decrease was noted for both drugs, while acetazolamide had a marked influence on pO2. The results indicate that the baboon model is sensitive for evaluation of drug effects on cerebral blood flow.

Estimation of regional cerebral blood flow using N-isopropyl-p-123I iodoamphetamine acquisition data from the lungs and brain

2014 ◽  
Vol 53 (06) ◽  
pp. 221-226
Author(s):  
S. Abe ◽  
Y. Takahashi ◽  
N. Fujita ◽  
M. Ikeda ◽  
N. Ota ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Regional Cerebral Blood Flow ◽  
Photon Emission ◽  
Previous Method ◽  
Emission Computed Tomography ◽  
Regional Cerebral Blood ◽  
Arterial Blood ◽  
The Mean ◽  
Method R

Summary Aim: Previously, we devised a method for estimating 123I labeled N-isopropyl-p-iodo- amphetamine (123I IMP) arterial blood activity at 10 minutes after intravenous injection of 123I IMP (Ca10) without any blood sampling using 123I IMP autoradiography (ARG) acquisition data, and verified its usefulness for quantification of regional cerebral blood flow (rCBF). In this study, we attempted to develop an improved noninvasive method for estimating rCBF. Patients, methods: 123I IMP studies with 23 patients and 15O-H2O positron emission tomography (PET) ARG studies with 20 patients were evaluated. Multiple regression analysis was used to estimate an integral of the arterial blood counts during the time after injection of 123I (JCa) using parameters from the time series of the lung counts and brain counts as the explanatory variables and the fraction [brain single-photon emission computed tomography (SPECT) average count / the mean of rCBFs (mean CBF) measured by 15O-H2O PET ARG method] as the objective variable. Results: The regression equation was as follows: Estimated JCa = (7.09x10-3 · Cb12) - (1.57x10-4 · CbpreSPECT) + (9.48x10-5 · CbpostSPECT) + (1.35x10-4· L15) - (6.95x10-4· L33) + (7.61x10-4· L81) - (0.417), where Cb12: brain count at 12 minutes, Cbpre-SPECT: brain count before SPECT, Cbpost-SPECT: brain count after SPECT, L15, L33, and L81: lung count at 15, 33, and 81 seconds, respectively. The mean CBF values (ml/min/100g) calculated using the estimated JCa values more closely correlated with those measured by 15O-H2O PET ARG method (r = 0.833, p < 0.01) than those obtained by our previous method (r = 0.590, p < 0.01). Conclusion: The rCBFs obtained by this method approximated more accurately to the values measured by 15O-H2O PET ARG method than those obtained by our previous method.

Heterogeneity of Cerebral Blood Flow: a Fractal Approach

2000 ◽  
Vol 39 (02) ◽  
pp. 37-42 ◽  
Author(s):  
P. Hartikainen ◽  
J. T. Kuikka
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Fractal Dimension ◽  
Frontal Lobe ◽  
Fractal Analysis ◽  
Relative Dispersion ◽  
Emission Computed Tomography ◽  
Brain Blood Flow ◽  
Healthy Controls ◽  
Fractal Approach

Summary Aim: We demonstrate the heterogeneity of regional cerebral blood flow using a fractal approach and singlephoton emission computed tomography (SPECT). Method: Tc-99m-labelled ethylcysteine dimer was injected intravenously in 10 healthy controls and in 10 patients with dementia of frontal lobe type. The head was imaged with a gamma camera and transaxial, sagittal and coronal slices were reconstructed. Two hundred fifty-six symmetrical regions of interest (ROIs) were drawn onto each hemisphere of functioning brain matter. Fractal analysis was used to examine the spatial heterogeneity of blood flow as a function of the number of ROIs. Results: Relative dispersion (= coefficient of variation of the regional flows) was fractal-like in healthy subjects and could be characterized by a fractal dimension of 1.17 ± 0.05 (mean ± SD) for the left hemisphere and 1.15 ± 0.04 for the right hemisphere, respectively. The fractal dimension of 1.0 reflects completely homogeneous blood flow and 1.5 indicates a random blood flow distribution. Patients with dementia of frontal lobe type had a significantly lower fractal dimension of 1.04 ± 0.03 than in healthy controls. Conclusion: Within the limits of spatial resolution of SPECT, the heterogeneity of brain blood flow is well characterized by a fractal dimension. Fractal analysis may help brain scientists to assess age-, sex- and laterality-related anatomic and physiological changes of brain blood flow and possibly to improve precision of diagnostic information available for patient care.

scholarly journals Examination of Potential Mechanisms in the Enhancement of Cerebral Blood Flow by Hypoglycemia and Pharmacological Doses of Deoxyglucose

1997 ◽  
Vol 17 (1) ◽  
pp. 54-63 ◽  
Author(s):  
Naoaki Horinaka ◽  
Nicole Artz ◽  
Jane Jehle ◽  
Shinichi Takahashi ◽  
Charles Kennedy ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Glucose Metabolism ◽  
Plasma Glucose ◽  
Plasma Lactate ◽  
Insulin Hypoglycemia ◽  
Glucose Levels ◽  
Arterial Blood ◽  
Arterial Plasma

Cerebral blood flow (CBF) rises when the glucose supply to the brain is limited by hypoglycemia or glucose metabolism is inhibited by pharmacological doses of 2-deoxyglucose (DG). The present studies in unanesthetized rats with insulin-induced hypoglycemia show that the increases in CBF, measured with the [14C]iodoantipyrine method, are relatively small until arterial plasma glucose levels fall to 2.5 to 3.0 m M, at which point CBF rises sharply. A direct effect of insulin on CBF was excluded; insulin administered under euglycemic conditions maintained by glucose injections had no effects on CBF. Insulin administration raised plasma lactate levels and decreased plasma K+ and HCO3– concentrations and arterial pH. These could not, however, be related to the increased CBF because insulin under euglycemic conditions had similar effects without affecting CBF; furthermore, the inhibition of brain glucose metabolism with pharmacological doses (200 mg/kg intravenously) of DG increased CBF, just like insulin hypoglycemia, without altering plasma lactate and K+ levels and arterial blood gas tensions and pH. Nitric oxide also does not appear to mediate the increases in CBF. Chronic blockade of nitric oxide synthase activity by twice daily i.p. injections of NG-nitro-L-arginine methyl ester for 4 days or acutely by a single i.v. injection raised arterial blood pressure and lowered CBF in normoglycemic, hypoglycemic, and DG-treated rats but did not significantly reduce the increases in CBF due to insulin-induced hypoglycemia (arterial plasma glucose levels, 2.5-3 m M) or pharmacological doses of deoxyglucose.

scholarly journals Cerebral blood flow autoregulation in ischemic heart failure

2017 ◽  
Vol 312 (1) ◽  
pp. R108-R113 ◽  
Author(s):  
J. R. Caldas ◽  
R. B. Panerai ◽  
V. J. Haunton ◽  
J. P. Almeida ◽  
G. S. R. Ferreira ◽  
...  
Keyword(s):  
Heart Failure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Healthy Volunteers ◽  
Neurological Complications ◽  
Ischemic Heart ◽  
Step Response ◽  
Ischemic Heart Failure ◽  
Arterial Blood ◽  
End Tidal

Patients with ischemic heart failure (iHF) have a high risk of neurological complications such as cognitive impairment and stroke. We hypothesized that iHF patients have a higher incidence of impaired dynamic cerebral autoregulation (dCA). Adult patients with iHF and healthy volunteers were included. Cerebral blood flow velocity (CBFV, transcranial Doppler, middle cerebral artery), end-tidal CO2 (capnography), and arterial blood pressure (Finometer) were continuously recorded supine for 5 min at rest. Autoregulation index (ARI) was estimated from the CBFV step response derived by transfer function analysis using standard template curves. Fifty-two iHF patients and 54 age-, gender-, and BP-matched healthy volunteers were studied. Echocardiogram ejection fraction was 40 (20–45) % in iHF group. iHF patients compared with control subjects had reduced end-tidal CO2 (34.1 ± 3.7 vs. 38.3 ± 4.0 mmHg, P < 0.001) and lower ARI values (5.1 ± 1.6 vs. 5.9 ± 1.0, P = 0.012). ARI <4, suggestive of impaired CA, was more common in iHF patients (28.8 vs. 7.4%, P = 0.004). These results confirm that iHF patients are more likely to have impaired dCA compared with age-matched controls. The relationship between impaired dCA and neurological complications in iHF patients deserves further investigation.

Diurnal variation in time to presyncope and associated circulatory changes during a controlled orthostatic challenge

2010 ◽  
Vol 299 (1) ◽  
pp. R55-R61 ◽  
Author(s):  
N. C. S. Lewis ◽  
G. Atkinson ◽  
S. J. E. Lucas ◽  
E. J. M. Grant ◽  
H. Jones ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Diurnal Variation ◽  
Flow Velocity ◽  
Blood Flow Velocity ◽  
Cerebral Blood Flow Velocity ◽  
Orthostatic Challenge ◽  
Arterial Blood ◽  
Neurally Mediated Syncope

Epidemiological data indicate that the risk of neurally mediated syncope is substantially higher in the morning. Syncope is precipitated by cerebral hypoperfusion, yet no chronobiological experiment has been undertaken to examine whether the major circulatory factors, which influence perfusion, show diurnal variation during a controlled orthostatic challenge. Therefore, we examined the diurnal variation in orthostatic tolerance and circulatory function measured at baseline and at presyncope. In a repeated-measures experiment, conducted at 0600 and 1600, 17 normotensive volunteers, aged 26 ± 4 yr (mean ± SD), rested supine at baseline and then underwent a 60° head-up tilt with 5-min incremental stages of lower body negative pressure until standardized symptoms of presyncope were apparent. Pretest hydration status was similar at both times of day. Continuous beat-to-beat measurements of cerebral blood flow velocity, blood pressure, heart rate, stroke volume, cardiac output, and end-tidal Pco2 were obtained. At baseline, mean cerebral blood flow velocity was 9 ± 2 cm/s (15%) lower in the morning than the afternoon ( P < 0.0001). The mean time to presyncope was shorter in the morning than in the afternoon (27.2 ± 10.5 min vs. 33.1 ± 7.9 min; 95% CI: 0.4 to 11.4 min, P = 0.01). All measurements made at presyncope did not show diurnal variation ( P > 0.05), but the changes over time (from baseline to presyncope time) in arterial blood pressure, estimated peripheral vascular resistance, and α-index baroreflex sensitivity were greater during the morning tests ( P < 0.05). These data indicate that tolerance to an incremental orthostatic challenge is markedly reduced in the morning due to diurnal variations in the time-based decline in blood pressure and the initial cerebral blood flow velocity “reserve” rather than the circulatory status at eventual presyncope. Such information may be used to help identify individuals who are particularly prone to orthostatic intolerance in the morning.

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