FV 449. Cerebral Blood Flow Volume and Gray Matter Volume across a Wide Age Range

Background: Physiological brain development has been of great scientific interest for many years. However, very little is known about the correlation of cerebral blood flow volume and gray matter volume. Color duplex sonography is an effective method to assess cerebral blood flow volume, whereas cerebral tissue volume can effectively be measured by magnetic resonance imaging (MRI).

Aim: The main aim of this work was to correlate cerebral blood flow volume (by means of color duplex sonography) and gray matter volume (by means of MRI) in a large number of subjects and across a wide age range from early infancy till old age.

Research Question: How do cerebral blood flow volume and gray matter volume correlate across lifetime, and are there effects of genders?

Methods: In earlier studies, the extracranial blood vessels (internal carotid and vertebral arteries) of 171 healthy subjects in an age range from 40 to 1,044 months (3–87 years) were examined by color duplex sonography. We analyzed the data with regard to the cerebral blood flow volume. Furthermore, 1,348 high-resolution T1-weighted 3D datasets of healthy subjects in an age range from 24 to 1,036 months (2–86 years) were analyzed with regard to global gray matter volume. The MRI datasets were collected from the C-MIND, the fCONN, and the IXI study. For a robust description of the chronological trends, additional neonatal starting points for both modalities were taken from the literature. Using a bootstrap resampling technique, we created 10,000 subsamples with a sampling ratio of 0.8 to which we fitted locally weighted polynomials. These were then analyzed using robust descriptive methods. The cerebral blood flow/tissue volume was generated by the division of the median blood flow volume by the median tissue volume per month.

Results: Cerebral blood flow volume peaks much earlier than gray matter volume, reaching its maximum at the age of 77 months. In contrast to this, gray matter volume only peaks at 112 months. Boys and girls have alternatingly higher cerebral blood flow volumes from birth to adulthood; however, from the age of 369 months on women consistently shows a significantly higher cerebral blood flow volume. Boys/men show significantly higher gray matter tissue volumes throughout lifetime. Cerebral blood flow/tissue volume shows its maximum early in life (68 months) and declines after that, with an intermittent increase between 204 and 316 months. Across mid-adulthood, the trend is slightly increasing (due to declining gray matter volume) and only in very old age cerebral blood flow/tissue volume does decline again. Comparing genders, girls show a later peak of the cerebral blood flow/tissue volume than boys, but from adolescence, they show a significantly higher cerebral blood flow/tissue volume.

Conclusion: Cerebral blood flow volume and gray matter tissue volume show similar trends during life, but they peak at different time points. Also, women tend to have higher cerebral blood flow volumes but lower gray matter volumes. Both findings indicate that gray matter volume itself is not the main factor driving higher cerebral blood flow volume.