How can MRI differentiate normal marrow signal from pathology in the vertebral bodies?

How can MRI differentiate normal marrow signal from pathology in the vertebral bodies?

• A. Normal red marrow intermediate T1; fatty marrow high T1; pathologic replacement lowers T1 and increases T2/PD; post-contrast enhancement patterns help
• B. Normal marrow is always bright on T1
• C. Pathology raises T1 signal and reduces T2 signal
• D. Post-contrast imaging is rarely used

Answer: (A)

Understanding marrow signal on MRI hinges on marrow composition. In adults, vertebral marrow shifts from red (hematopoietic) to yellow (fatty) marrow. Fatty marrow has high signal on T1-weighted images, so normal fatty marrow appears bright, while red marrow has intermediate T1 signal due to higher water content. When pathology replaces normal marrow—such as metastasis, infection, or marrow edema—the T1 signal drops (less fat, more water) and T2/PD signals rise because of increased water content. Post-contrast enhancement patterns further aid differentiation, with pathologic processes typically showing notable enhancement, reflecting tumor vascularity or inflammatory change. This combination—normal marrow with intermediate T1 for red and high T1 for yellow, pathologic replacement lowering T1 and increasing T2/PD, plus informative post-contrast enhancement—best explains how MRI distinguishes normal marrow signal from pathology in the vertebral bodies.

Understanding marrow signal on MRI hinges on marrow composition. In adults, vertebral marrow shifts from red (hematopoietic) to yellow (fatty) marrow. Fatty marrow has high signal on T1-weighted images, so normal fatty marrow appears bright, while red marrow has intermediate T1 signal due to higher water content. When pathology replaces normal marrow—such as metastasis, infection, or marrow edema—the T1 signal drops (less fat, more water) and T2/PD signals rise because of increased water content. Post-contrast enhancement patterns further aid differentiation, with pathologic processes typically showing notable enhancement, reflecting tumor vascularity or inflammatory change. This combination—normal marrow with intermediate T1 for red and high T1 for yellow, pathologic replacement lowering T1 and increasing T2/PD, plus informative post-contrast enhancement—best explains how MRI distinguishes normal marrow signal from pathology in the vertebral bodies.