Final answer:
In breast MRI, mass shapes such as round, oval, lobulated, and irregular provide diagnostic clues, with smooth margins usually indicating benign masses and irregular or spiculated margins suggesting malignancy.
Step-by-step explanation:
In breast MRI, various mass shapes have distinct implications and can help in the diagnosis of breast lesions. Common shapes include round, oval, lobulated, and irregular. The margin of the mass, which can be smooth, irregular, or spiculated, also provides important diagnostic clues. Round or oval masses with smooth margins tend to be benign, while irregular and spiculated masses are more suspicious for malignancy. However, any mass detected on MRI must be correlated with other imaging findings and histopathological results for accurate diagnosis.