Medical How does the contrast agent bind with breast tumor?

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This is a beginner question. In breast MRI, The gadolinium-based contrast agents reduces the T1 and T2 relaxation time of protons. My question is "how does the intravenously injected contrast agent knows where the breast tumor is and binds with the tumor?"

Many thanks.
 
The contrast agents do not actually bind to a tumor but enhance the MRI signal for the entire scan.
 
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If the response of the healthy breast tissue and malignant tissue are both enhanced, how would the contrast agents be able to accentuate the region of malignancy?
 

bobze

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If the response of the healthy breast tissue and malignant tissue are both enhanced, how would the contrast agents be able to accentuate the region of malignancy?
They don't. As Stormer pointed out they just enhance the signal for the scan, giving you a better picture which the radiologist can read. And since tissue densities and water properties are different, adding contrast allows better visual differentiation.
 
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Then I was mis-informed. The contrast agent more sounds like a lamp lit up a room. Everything is illuminated. Thx.
 

bobze

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Then I was mis-informed. The contrast agent more sounds like a lamp lit up a room. Everything is illuminated. Thx.
Yes, that's a pretty good analogy.
 
Actually , the T1 and T2 relaxation times of protons in malignant vs. normal cells are different for some malignancies). The presence of , e.g.. gadolinium nuclei in some of the MRI 'contrast agents', injected into the patient some time before the contrast MRI image acquisition 'enhances' this difference and MR radiologists who 'read' these images, pre- and post- contrast can deduce whether that imaged tissue is malignant or not.
 
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Actually , the T1 and T2 relaxation times of protons in malignant vs. normal cells are different for some malignancies). The presence of , e.g.. gadolinium nuclei in some of the MRI 'contrast agents', injected into the patient some time before the contrast MRI image acquisition 'enhances' this difference and MR radiologists who 'read' these images, pre- and post- contrast can deduce whether that imaged tissue is malignant or not.
Gadolinium and other paramagnetic contrast agents map blood flow. Malignant tumors are metabolically active and have "tumor vascularity" -- specific tumor growth factors recruit the growth of new blood vessels into the malignant tissue (neovascularity) to supply the increased metabolic needs of the malignant cells.

Breast MRI contrast agents are more like an arteriogram. The blood vessels and highly vascular tissue lights up, not the whole room. By taking a digital image before and after contrast, the before contrast image data can digitally subtracted from the after contrast image to create a maximum intensity projection (MIP) reconstructed in 3D, and the areas of increased vascularity are more readily apparent. In addition to vascularity, tumor morphology and the appearance of the lesion on both mammograms and ultrasound help to differentiate benign from malignant lesions. Both benign and malignant lesions can enhance with contrast.

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