Calculation Of Cerebral Blood Flow Research Articles

Rapid Quantitative Measurement of CMRO2 and CBF by Dual Administration of 15O-Labeled Oxygen and Water During a Single PET Scan—a Validation Study and Error Analysis in Anesthetized Monkeys

Cerebral blood flow (CBF) and rate of oxygen metabolism (CMRO(2)) may be quantified using positron emission tomography (PET) with (15)O-tracers, but the conventional three-step technique requires a relatively long study period, attributed to the need for separate acquisition for each of (15)O(2), H(2)(15)O, and C(15)O tracers, which makes the multiple measurements at different physiologic conditions difficult. In this study, we present a novel, faster technique that provides a pixel-by-pixel calculation of CBF and CMRO(2) from a single PET acquisition with a sequential administration of (15)O(2) and H(2)(15)O. Experiments were performed on six anesthetized monkeys to validate this technique. The global CBF, oxygen extraction fraction (OEF), and CMRO(2) obtained by the present technique at rest were not significantly different from those obtained with three-step method. The global OEF (gOEF) also agreed with that determined by simultaneous arterio-sinus blood sampling (gOEF(A-V)) for a physiologically wide range when changing the arterial PaCO(2) (gOEF=1.03gOEF(A-V)+0.01, P<0.001). The regional values, as well as the image quality were identical between the present technique and three-step method for CBF, OEF, and CMRO(2). In addition, a simulation study showed that error sensitivity of the present technique to delay or dispersion of the input function, and the error in the partition coefficient was equivalent to that observed for three-step method. Error sensitivity to cerebral blood volume (CBV) was also identical to that in the three-step and reasonably small, suggesting that a single CBV assessment is sufficient for repeated measures of CBF/CMRO(2). These results show that this fast technique has an ability for accurate assessment of CBF/CMRO(2) and also allows multiple assessment at different physiologic conditions.

Quantitative Measurement of Local Cerebral Blood Flow in the Anesthetized Mouse Using Intraperitoneal [14C]Iodoantipyrine Injection and Final Arterial Heart Blood Sampling

Autoradiographic measurement of local cerebral blood flow (CBF) with [14C]iodoantipyrine (IAP) is limited in mice by the difficulty in cannulating vessels and the blood loss for repeated blood sampling. The authors modified and validated the method to measure local CBF with [14C]IAP in mice by combining intraperitoneal tracer application with a single blood sampling from the heart at the end of the experiment. Experiments were carried out in male SV129 mice under halothane anesthesia. After intraperitoneal administration of 15 microCi [14C]IAP, arterial blood samples were collected repeatedly and anesthetized animals were immersed in liquid nitrogen. In addition, frozen blood from the heart was sampled to obtain the final blood [14C]radioactivity. Correlation analysis between the sampling time and [14C]radioactivity of the arterial blood revealed a highly significant linear relationship (P < 0.001, r = 0.978) and a lag time of the [14C]tracer in arterial blood of 3.3 +/- 0.6 seconds. [14C]radioactivity of the final arterial blood sample (444 +/- 264 nCi/mL) was almost equal to that of the heart blood (454 +/- 242 nCi/mL), and the absolute difference in each animal was 3.3 +/- 4.2% (mean +/- SD). The convolution integrals for the CBF calculation were determined either by integrating the radioactivity of individual arterial blood samples or by assuming a linear rise from [14C]tracer lag time after intraperitoneal [14C]IAP injection to the value measured in the blood sample from the frozen heart. Regional flow values calculated by the two methods differed by less than 11% (not significant). This method allows the quantitative measurement of local CBF in anesthetized mice without any vessel catheterization and will make mutant mice a more powerful tool to elucidate the molecular mechanisms of brain injuries by combining flow studies with molecular-biological methods.

Cerebral blood flow: measurement with xenon-enhanced dynamic helical CT.

To improve CT number reproducibility in helical CT, a newly developed controlled-orbit helical scan mechanism was applied. The authors developed a method for volumetric measurement of cerebral blood flow (CBF) with dynamic helical computed tomography (CT) after inhalation of xenon gas. In three subjects (two healthy men aged 22 and 38 years and a 7-year-old girl with moyamoya disease), six helical scans were obtained during 6-minute xenon inhalation, and CT scans with 41 sections in 2-mm increments were reconstructed from each scan. Conventional CBF calculation was then applied to the CT images. CBF maps of 40 sections for each subject of sufficient diagnostic quality were obtained with a 39-cGy radiation dose. The spatial resolution was 2.5 line pairs per centimeter. This volumetric CBF mapping method is applicable in clinical practice because of the short examination time and acceptable radiation dose.

Nicergoline et hemodetournement en faveur des zones d'hypodebit dans les accidents ischemiques cerebraux

Hemispheric and regional variations of cerebral blood flow (CBF) were studied with the Xenon inhalation technique on 19 patients suffering from cerebral infarcts before and at the end of a 10 mg 'alpha-blocking' Nicergoline perfusion. CBF dynamic images and calculations were performed with a gamma computerized camera. No significant hemispheric CBF modification has been noted after Nicergoline perfusion (30.2 +/- 4.5 ml/min/100 g before perfusion and 31 +/- 5.6 ml/min/100 g at the end of perfusion) but, at the end of perfusion, we noticed a CBF increase on the more ischemic areas (25.7 +/- 5.6 ml/min/100 g before and 29.9 +/- 6.8 ml/min/100 g after). This variation depends on the patients (from +67% to -22%). The more ischemic areas are those with the more important CBF increase. This 'inverse steel effect' is comparable to the effect described by other authors for Vincamine or Piracetam.