If you are getting a scan soon after the PSMA scan then it would have to be one of those other types. Normally, you would get those for cases where your metastasis are not producing PSMA. You can also get them to find metastasis that are smaller than can be seen on the PSMA scan. At one conference, they said that the smallest size is 2.7 mm but then yesterday UCSF had a conference where they said you really had a problem seeing them if they were under 5 mm.