Sacral metastases MRI
Sacral metastases refer to cancerous cells that have spread to the sacral bone from another part of the body. This occurs as part of the process known as metastasis, where cancer cells break away from the original tumor, travel through the bloodstream or lymphatic system, and form new tumors in other organs or tissues.
Causes
Sacral metastases usually arise from cancers that have a tendency to spread to the bone. The most common types of primary cancers that may lead to sacral metastases include:
- Breast cancer
- Prostate cancer
- Lung cancer
- Kidney cancer
- Thyroid cancer
Symptoms
Symptoms of sacral metastases can vary depending on the extent of bone involvement and whether there are associated complications like nerve compression. Common symptoms include:
- Persistent, progressive pain in the lower back, hips, or legs
- Numbness or weakness in the legs
- Difficulty with bowel and bladder function
- Reduced mobility
Diagnosis
Diagnosing sacral metastases typically involves a combination of clinical evaluation and imaging studies, along with biopsy if necessary. Common diagnostic tools include:
- X-rays: Useful for detecting changes in bone structure.
- MRI and CT scans: Provide detailed images of bone and surrounding soft tissues, helping to assess the extent of tumor spread.
- Bone scans: Help in identifying active bone lesions that may not be visible on X-rays.
- Biopsy: Involves taking a small sample of tissue from the sacral area to confirm the presence of cancer cells.
Treatment
Treatment for sacral metastases is primarily aimed at controlling pain and maintaining mobility, as well as addressing the primary cancer. Treatment options include:
- Radiation therapy: Can be effective in relieving pain and reducing the size of the metastatic tumors.
- Surgery: In cases where there is significant structural damage to the sacrum or risk of fracture, surgery might be necessary to stabilize the bone and alleviate nerve compression.
- Chemotherapy and Hormonal Therapy: Depending on the primary cancer, these treatments might be used to control the spread of cancer.
- Targeted Therapy and Immunotherapy: These newer treatments are selected based on the specific genetic markers and characteristics of the cancer cells and can be effective against some types of tumors.
MRI Appearance of Sacral metastases
MRI T1 Appearance of Sacral Metastases
On T1-weighted MRI, sacral metastases typically appear as hypointense (dark) areas compared to the normal fatty marrow, which exhibits a high signal intensity. The infiltrative nature of metastatic lesions results in the replacement of normal marrow fat, leading to this characteristic low signal. The contrast between the dark metastatic lesions and the bright signal of normal marrow provides a clear indication of the extent and location of the metastatic involvement.
MRI T2 Appearance of Sacral Metastases
T2-weighted MRI sequences show sacral metastases as hyperintense (bright) regions relative to the surrounding bone marrow and soft tissues. This increased signal intensity is due to the higher water content within the metastatic lesions, which is a result of tumor infiltration, edema, and potential necrosis. The bright appearance of the lesions on T2-weighted images helps in delineating the extent of metastatic spread and is useful for identifying associated soft tissue involvement.
MRI STIR Appearance of Sacral Metastases
Short Tau Inversion Recovery (STIR) sequences are highly sensitive to the presence of edema and increased water content, making them ideal for detecting sacral metastases. On STIR images, metastatic lesions appear as markedly hyperintense (very bright) areas against the suppressed background of normal fatty marrow. The suppression of fat signal enhances the visibility of the lesions, highlighting the infiltrative and often extensive nature of metastatic disease in the sacrum.
MRI T1 Post-Contrast Appearance of Sacral Metastases
Following the administration of a gadolinium-based contrast agent, T1-weighted post-contrast MRI sequences typically show sacral metastases as areas of variable enhancement. The degree of enhancement depends on the vascularity of the metastatic lesions. Well-vascularized tumors exhibit significant enhancement, appearing bright on post-contrast images, while poorly vascularized or necrotic areas may show minimal or no enhancement. This contrast enhancement helps to better delineate the margins of the metastatic lesions and assess the involvement of adjacent structures.
T2 sagittal image of lumbosacral spine shows Sacral Metastases
![T2 sagittal image of lumbosacral spine shows Sacral Metastases](/wp-content/uploads/2024/06/T2-sagittal-image-of-lumbosacral-spine-shows-Sacral-Metastases-1024x598.jpg)
T1 sagittal image of lumbosacral spine shows Sacral Metastases
![T1 sagittal image of lumbosacral spine shows Sacral Metastases](/wp-content/uploads/2024/06/T1-sagittal-image-of-lumbosacral-spine-shows-Sacral-Metastases-1024x598.jpg)
STIR sagittal image of lumbosacral spine shows Sacral Metastases
![STIR sagittal image of lumbosacral spine shows Sacral Metastases](/wp-content/uploads/2024/06/STIR-sagittal-image-of-lumbosacral-spine-shows-Sacral-Metastases-1024x598.jpg)
T2 TSE axial image of image of lumbosacral spine shows Sacral Metastases
![T2 axial image of lumbosacral spine shows Sacral Metastases](/wp-content/uploads/2024/06/T2-axial-image-of-lumbosacral-spine-shows-Sacral-Metastases-1024x598.jpg)
![T2 axial image of lumbosacral spine shows Sacral Metastases 2](/wp-content/uploads/2024/06/T2-axial-image-of-lumbosacral-spine-shows-Sacral-Metastases-2-1024x598.jpg)
T1 TSE axial image of lumbosacral spine shows Sacral Metastases
![T1 axial image of lumbosacral spine shows Sacral Metastases](/wp-content/uploads/2024/06/T1-axial-image-of-lumbosacral-spine-shows-Sacral-Metastases.jpg)
![T1 axial image of lumbosacral spine shows Sacral Metastases 2](/wp-content/uploads/2024/06/T1-axial-image-of-lumbosacral-spine-shows-Sacral-Metastases-2-768x449.jpg)
References
- Vanheule, E., Huysse, W., Herregods, N., Verstraete, K., & Jans, L. (2019). Sacral Tumours on MRI: A Pictorial Essay. J Belg Soc Radiol, 103(1), 62.
- Thornton, E., Krajewski, K. M., O’Regan, K. N., Giardino, A. A., Jagannathan, J. P., & Ramaiya, N. (2012). Imaging features of primary and secondary malignant tumours of the sacrum. British Journal of Radiology, 85(1011), 279–284.
- Quraishi, N. A., Giannoulis, K. E., Edwards, K. L., & Boszczyk, B. M. (2012). Management of metastatic sacral tumours. European Spine Journal, 21(10), 1984–1993.
- Charest-Morin, R., Fisher, C. G., Versteeg, A. L., Sahgal, A., Varga, P. P., Sciubba, D. M., Schuster, J. M., Weber, M. H., Clarke, M. J., Rhines, L. D., Boriani, S., Bettegowda, C., Fehlings, M. G., Arnold, P. M., Gokaslan, Z. L., & Dea, N. (2019). Clinical presentation, management and outcomes of sacral metastases: A multicenter, retrospective cohort study. Annals of Translational Medicine, 7(10), 214. doi: 10.21037/atm.2019.04.88. PMCID: PMC6595205. PMID: 31297379.