Novel benzamide compounds of Formula (I), Formula (II) and Formula (III, salts, water soluble salts, analogs and radiolabeled counterparts thereof as sigma-2 receptor radiotracers for imaging the proliferative status of solid tumors. A method for diagnosing a mammal for the presence of a mammalian tumor therein comprises administering to the mammal a diagnostic imaging detectable effective amount of a benzamide compound having a structure illustrated in Formula (I), Formula (II) and Formula (III) and detecting binding of the compound to a tumor in the mammal. A method for diagnostic imaging of a mammalian tissue having cell surface sigma-2 receptors comprising administering to a mammal a diagnostic imaging amount of a compound having a structure illustrated in Formula (I) Formula (II) and Formula (III) and detecting an image of a tissue having an ample cells with sigma-2 receptors.