A suitable formulation of a diagnostic claim according to Art. 54(5) may read:

Substance X
or
Composition comprising X

for use in a method of diagnosis

"in vivo"

of disease Y

The wording "in vivo" limits the scope of the claim to diagnostic methods which are excluded from patentability pursuant to Art. 53(c).

If the independent claim is directed to a composition, the definition of the composition may be inserted before or after the term "for use".

Purpose-related product claims which do not define a diagnostic use excluded from patentability under Art. 53(c) are construed as claims directed to a product per se which is suitable for the claimed use.

The following table shows some examples of claims which do not define a diagnostic use within the meaning of Art. 53(c):

1. Substance X or Composition comprising X

for use in the diagnosis of disease Y,
or for use in the "in vitro"/"ex vivo" diagnosis of disease Y

2. Substance X or Composition comprising X

for use as a contrast agent for imaging blood flow

Claims 1 and 2 would lack novelty over prior art disclosing either the product per se in a form which could be considered suitable for the claimed use, or its first medical application.

Claim 1 could be reformulated as "Use of [...] in the "in vitro/ex vivo" diagnosis of disease Y". If the application as filed discloses, either explicitly or implicitly, that the claimed diagnostic methods are to be carried out "in vivo", the wording of claim 1 could also be limited to encompass only "in vivo" methods, as described above.

Claim 2 could be reformulated as "Use of [...] as contrast agent for imaging blood flow".

Claims 1 and 2 could also be reformulated as method claims, e.g. "A method for in vitro/ex vivo diagnosing disease Y using substance X [...]" or " A method for diagnosing disease Y in a sample by using substance X [...]" or "A method of imaging blood flow using substance X [...]".

These amendments may be proposed by the examining division in the Rule 71(3) communication without the need to consult the applicant beforehand (see C‑V, 1.1, point (f)).