How to find graph centre of Subgraph

Hello I am working on a huge graph over 1 billion nodes. I have created a subgraph after performing some filters where I am keeping 2 hop distance from particular node . I need to find out the centre node or list of centre nodes using cypher. can you give some guidelines. I need to check centre nodes for further analysis purpose
Thank you

If you want to calculate graph centrality, then you can use the Graph Algorithms plugin, and you can use PageRank for example.

Thanks for your answer
I want to find a graph centre where its eccentricity is equal to radius. The graph centre node or nodes are most influential nodes I suppose.

I see.
So, the diameter is the maximum shortest path I guess, so you can do something like this:

MATCH (a:Node), (b:Node) WHERE id(a) > id(b)
MATCH p=shortestPath((a)-[:RELATIONSHIP*]-(b))
WITH length(p) AS len, p
RETURN len, extract(x IN nodes(p) | x) AS path

Then you can check the path at half way. This is my quick guess.