I wanted to use Matrix.CreatePerspectiveOffCenter() recently but had a little trouble converting from my usage of Matrix.CreatePerspective(). The latter method requires field of view, aspect ratio and near far distances, the former requires the boundaries of the near plane in view space. Fortunately, calculating the near plane size is just a little simple trigonometry.
// tan(angle) = opposite / adjacent
// opposite = adjacent * tan(angle)
float nearPlaneHSize = nearClip * (float)Math.Tan(fov*0.5f);
projection = Matrix.CreatePerspectiveOffCenter(
-nearPlaneHSize * aspectRatio,
nearPlaneHSize * aspectRatio,
-nearPlaneHSize, nearPlaneHSize,
nearClip, farClip);