GetTypeSpecs.cs

using System;
using System.Reflection.Metadata;
using System.Reflection.Metadata.Ecma335;
using System.Reflection.PortableExecutable;

class Program
{
    static void Main()
    {
        using (var pe = new PEReader(...))
        {
            MetadataReader md = pe.GetMetadataReader();

            for (int row = 1, count = md.GetTableRowCount(TableIndex.TypeSpec); row <= count; row++)
            {
                TypeSpecificationHandle handle = MetadataTokens.TypeSpecificationHandle(row);
                TypeSpecification specification = md.GetTypeSpecification(handle);
                ...
            }
        }
    }
}