On the validity of blood flow measurement using colored microspheres

Abstract

The aim of this study was 1) to investigate the validity of repeated estimations of blood flow using colored microspheres (CMS) and 2) to develop and validate a method that permits four consecutive estimations in the same animal using nonradiolabeled microspheres (NRMS). Several mixtures of different types of microspheres were injected in dogs, with each mixture containing the radiolabeled microspheres (RMS; labeled with113Sn) with either three CMS, four CMS, or three CMS and one type of fluorescent (crimson labeled) microsphere (FMS). The blood flows estimated with the use of any of the injected microspheres were compared with those measured using the RMS as the “gold standard.” The results were analyzed by 1) regression analysis, 2) variance analysis (ANOVA I), and 3) estimation of the limits of agreement between RMS and NRMS flow rates. The results indicate that simultaneous estimations of blood flow obtained with the use of more than three CMS lack accuracy and reliability. A combination of three types of CMS with crimson-labeled FMS, however, offers the possibility to estimate consecutively four different flow rates in the same animal in an accurate way and with relatively high precision.

Effects of Dopamine, Dobutamine, Amrinone and Milrinone on Regional Blood Flow in Isoflurane Anesthetized Dogs

“…This technique enabled to measure blood flow of all organs simultaneously and repeatedly, however the dispersion of data among the individuals was relatively large. Although CM technique is easy to be performed, some technical problems such as the risk of losing CM during filtration process or overlapping of the extract have been reported [15,22,36].…”

Donepezil, an acetylcholinesterase inhibitor against Alzheimer's dementia, promotes angiogenesis in an ischemic hindlimb model

“…According to previous studies using fluorescent microspheres [15,16], we evaluated the relative blood flow between the left and right hindlimbs in mice. Briefly, after anesthesia, 200 L of green FluoSphere fluorescent microspheres (15 m, Molecular Probes, Invitrogen, Carlsbad, CA, USA) were administered within 1 min, followed by immediate sampling of blood and bilateral quadriceps femoris muscles.…”

Blood flow measurements in rats using four color microspheres during blockade of different vasopressor systems

“…Recently, Prinzen and Bassingthwaighte (1) discussed the pros and cons of radioactive, colored and fluorescent microspheres. The CM technique allows the measurement of regional blood flow in a manner quite similar to that of radioactive microspheres (4,7,8,13) while avoiding the disadvantage of radioisotope decay, limiting their lifetime, and the handling of radioactive materials. In a study that used fluorescent and CM simultaneously and compared them with radioactive microspheres, no differences were found in the accuracy of blood flow values obtained with the two types of non-radioactive spheres (7).…”

“…The use of colored microspheres (CM) represents a simple and safe method, especially because it avoids the radiation associated with radioactive spheres (2)(3)(4). Frequently, repeated blood flow measurements must be performed in the same animal (same tissue or organ) (5)(6)(7). For this purpose, microspheres labeled with different color components are injected, and the components are then measured simultaneously.…”

“…However, the determination of the amount of the different components may be disturbed by interference between the different absorption spectra. Indeed, CM have been further validated (4,6,8) and employed extensively, although usually with a maximum of three different colors (7). The present study was designed to test the possibility to use four different microsphere colors: white (370 nm), yellow (448 nm), red (530 nm), and blue (672 nm).…”