18641
Thus , a number of aminophosphonate complexes of platinum group metals have been found to possess remarkable antitumor activity while complexes of some other transition and rare - earth metals like technetium , rhenium , samarium and gadolinium have been used either as therapeutic and diagnostic radiopharmaceuticals or as magnetic resonance imaging ( MRI ) contrast agents .
 aminophosphonate, platinum, technetium, rhenium, samarium, gadolinium
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 aminophosphonate, platinum, technetium, rhenium, samarium, gadolinium