Methods for making ultrasound contrast agents

Abstract

Provided herein are improved methods for preparing phospholipid formulations including phospholipid UCA formulations.

1 - 27 . (canceled) 
     
     
         28 . A method of ultrasound contrast imaging a subject comprising
 (a) selecting an MPEG5000-DPPE having calcium and/or magnesium divalent metal cation present at a total divalent metal cation concentration of less than 115 parts per million (ppm),   (b) combining the MPEG-5000-DPPE with one or more phospholipids and a non-aqueous solvent, to form a phospholipid solution having calcium and/or magnesium divalent metal cation present at a total divalent metal cation concentration of less than 0.7 ppm,   (c) combining the phospholipid solution with an aqueous solution to form a phospholipid suspension,   (d) activating the phospholipid suspension with a perfluorocarbon gas to form lipid-encapsulated gas microspheres,   (e) administering the lipid-encapsulated gas microspheres to a subject, and   (f) obtaining an ultrasound image of the subject.   
     
     
         29 . The method of  claim 28 , wherein the one or more phospholipids comprise DPPC and/or DPPE. 
     
     
         30 . The method of  claim 28 , wherein the one or more phospholipids exclude DPPA. 
     
     
         31 . The method of  claim 29 , wherein the one or more phospholipids comprise DPPC, and the DPPC has a combined calcium and magnesium concentration of less than 90 ppm. 
     
     
         32 . The method of  claim 28 , wherein the non-aqueous solvent comprises propylene glycol. 
     
     
         33 . The method of  claim 28 , wherein the non-aqueous solvent has a combined calcium and magnesium concentration of less than 0.7 ppm. 
     
     
         34 . The method of  claim 28 , wherein the non-aqueous solvent comprises propylene glycol and glycerol. 
     
     
         35 . The method of  claim 29 , wherein the MPEG-5000-DPPE is present in the phospholipid solution in a molar percentage of 5-15%. 
     
     
         36 . The method of  claim 29 , wherein the one or more phospholipids comprise DPPC, and the DPPC is present in the phospholipid solution in a molar percentage of 77-90%. 
     
     
         37 . The method of  claim 36 , wherein DPPC and MPEG-5000-DPPE are present in the phospholipid solution in a mole % ratio of 82 to 8 (82:8). 
     
     
         38 . The method of  claim 28 , wherein the perfluorocarbon gas is perfluoropropane gas. 
     
     
         39 . The method of  claim 28 , wherein the one or more phospholipids comprise DPPC, the phospholipid solution comprises DPPC, MPEG5000-DPPE and propylene glycol, the aqueous solution comprises water, propylene glycol and glycerol, and the phospholipid suspension comprises DPPC, MPEG5000-DPPE, propylene glycol, water and glycerol. 
     
     
         40 . The method of  claim 28 , wherein the aqueous solution further comprises one or more salts. 
     
     
         41 . The method of  claim 28 , wherein the aqueous solution further comprises one or more buffers. 
     
     
         42 . A method of ultrasound contrast imaging a subject comprising
 (a) combining one or more solid form phospholipids and a non-aqueous solvent, to form a phospholipid solution having calcium and/or magnesium divalent metal cation present at a total divalent metal cation concentration of less than 0.7 parts per million (ppm), and   (b) combining the phospholipid solution with an aqueous solution to form a phospholipid suspension, and   (c) activating the phospholipid suspension with a perfluorocarbon gas to form lipid-encapsulated gas microspheres,   (d) administering the lipid-encapsulated gas microspheres to a subject, and   (e) obtaining an ultrasound image of the subject.   
     
     
         43 . A composition comprising a phospholipid suspension in contact with a perfluoropropane gas, wherein the phospholipid suspension comprises
 (a) a saline solution, and   (b) a phospholipid solution
 (i) comprising one or more phospholipids comprising MPEG5000-DPPE, 
 (ii) having a divalent metal ion concentration of less than 0.7 parts per million (ppm), and 
 (iii) comprising none, one or two but not all three of methanol, toluene and methyl t-butyl ether (MTBE). 
   
     
     
         44 . The composition of  claim 43 , wherein the one or more phospholipids further comprise DPPA and DPPC.