Nano-scale contrast agents and methods of use

1. A method for evaluating a subject's vasculature integrity, the method comprising:

introducing a composition into the subject's vasculature, the composition comprising: liposomes, the liposomes encapsulating one or more iodinated nonradioactive contrast enhancing agents, and the liposomes comprising: cholesterol, at least one phospholipid, and at least one phospholipid which is derivatized with a polymer chain, wherein the average diameter of the liposomes is less than 150 nanometers;

generating images of the subject's vasculature; and

analyzing the images to detect a leak in the subject's vasculature.

2. The method of claim 1 , wherein the generating images comprises generating X-ray images.

3. The method of claim 1 , wherein the generating images comprises generating images before and after introducing the composition into the subject's vasculature.

4. The method of claim 1 , wherein the analyzing the images comprises distinguishing areas having an enhanced signal from areas having little or no signal.

5. The method of claim 1 , wherein the composition is characterized in that the composition accumulates in an extravascular region of the subject's vasculature when a leak exists in the subject's vasculature, in comparison to an intravascular region of the subject's vasculature, thereby enhancing the signal in the extravascular region.

6. The method of claim 2 , wherein the generating X-ray images comprises generating X-ray images using at least one of computed tomography, micro-computed tomography, mammography, and chest X-ray.

7. The method of claim 1 , wherein the generating images comprises generating images using at least one of MRI, ultrasound, and optical imaging, including fluorescence or bioluminescence imaging.

8. The method of claim 1 , wherein the leak is indicative of at least one of cancer, stroke, aneurism, healing, and trauma.

9. A method for differentiating between a malignant lesion and a benign lesion, the method comprising:

introducing a composition into a lesion of interest, the composition comprising:

liposomes, the liposomes comprising:

at least one first lipid or phospholipid;

at least one second lipid or phospholipid which is derivatized with one or more polymers;

at least one sterically bulky excipient capable of stabilizing the liposomes, wherein the average diameter of the liposomes is less than 150 nanometers, and wherein the liposomes encapsulate at least one iodinated nonradioactive contrast enhancing agent;

generating images of the lesion of interest; and

analyzing the images to determine the extent of accumulation of the composition in the lesion of interest.

10. The method of claim 9 , wherein the composition is characterized in that the composition accumulates in a malignant lesion to a greater extent than in a benign lesion.

11. The method of claim 9 , wherein the generating images comprises generating X-ray images.

12. A method for evaluating the accessibility of a tumor to nano-sized therapeutics, the method comprising:

introducing a composition into the tumor, the composition comprising: liposomes, the liposomes comprising: at least one first lipid or phospholipid; at least one second lipid or phospholipid which is derivatized with one or more polymers; and at least one sterically bulky excipient capable of stabilizing the liposomes, wherein the average diameter of the liposomes is less than 150 nanometers, and wherein the liposomes encapsulate at least one iodinated nonradioactive contrast enhancing agent;

generating images of the tumor; and

analyzing the images to determine the extent of accumulation of the composition in the tumor.

13. The method of claim 12 , wherein the generating images comprises generating X-ray images.

14. A method for treating a tumor and monitoring the treatment, comprising:

introducing a composition into the tumor, the composition comprising:

liposomes, the liposomes comprising:

at least one first lipid or phospholipid;

at least one second lipid or phospholipid which is derivatized with one or more polymers; and

cholesterol,

wherein the liposomes co-encapsulate:

at least one iodinated nonradioactive contrast enhancing agent; and

at least one bioactive agent,

and wherein the average diameter of the liposomes is less than 150 nanometers; and

generating X-ray images of the tumor.

15. The method of claim 14 , wherein the tumor is a cancerous tumor.

16. The method of claim 14 , wherein the at least one first lipid or phospholipid comprises 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC).

17. The method of claim 14 , wherein the at least one second lipid or phospholipid which is derivatized with one or more polymers comprises N-carbamylmethoxypoly(ethylene glycol)-1,2-distearoyl-sn-glycerol-3-phosphoethanolamine (mPEG(2000)-DSPE).

18. The method of claim 14 , wherein the at least one iodinated nonradioactive contrast enhancing agent comprises at least one of iodixanol and iohexol.

19. The method of claim 14 , wherein the at least one bioactive agent comprises a chemotherapeutic agent.

20. The method of claim 14 , wherein the at least one bioactive agent comprises doxorubicin.

21. The method of claim 14 , wherein the tumor is a cancerous tumor, and wherein:

the at least one first lipid or phospholipid comprises 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC);

the at least one second lipid or phospholipid which is derivatized with one or more polymers comprises N-carbamylmethoxypoly(ethylene glycol)-1,2-distearoyl-sn-glycerol-3-phosphoethanolamine (mPEG(2000)-DSPE),

wherein the DPPC, the cholesterol, and the mPEG(2000)-DSPE are present in a molar ratio of approximately 55:40:5,

wherein the at least one iodinated nonradioactive contrast enhancing agent comprises at least one of iodixanol and iohexol,

and wherein the at least one bioactive agent comprises doxorubicin.

22. The method of claim 14 , wherein the average diameter of the liposomes is about 100 nanometers.

23. The method of claim 14 , wherein the encapsulated liposomal iodine is about 91 mg/mL and the bioactive agent content is about 1.2 mg/mL.