Vertebral metastasis is the most common tumor of the spine, with 70% of all bone metastases located in the vertebrae. Breast (21%), lung (19%), prostate (7.5%), kidney (5%), and thyroid (3%) are the most common primary sources. Hematogenous spread through the Batson venous plexus is the main mechanism — the valveless paravertebral venous system allows retrograde flow to vertebral bone marrow during Valsalva maneuver. Osteolytic metastasis is the most common type (breast, lung, kidney, thyroid), osteoblastic metastasis is from prostate, and mixed pattern is also common. Lumbar spine is most commonly affected (52%), followed by thoracic (36%) and cervical (12%). MRI is the most sensitive modality — T1 hypointense signal of tumor replacing fatty marrow is the earliest finding. STIR, diffusion MRI, and contrast-enhanced MRI are complementary. CT is superior for cortical destruction and osteoblastic lesion evaluation. PET-CT (FDG or NaF) is used for whole-body staging. Pathologic fracture and spinal cord compression (epidural metastasis) are urgent clinical situations requiring MESCC protocol.
Age Range
40-85
Peak Age
65
Gender
Equal
Prevalence
Common
The pathogenesis of vertebral metastasis involves three main mechanisms: hematogenous spread (most common), direct invasion, and lymphatic spread. The Batson venous plexus is the main anatomical factor explaining the frequency of vertebral metastasis — the valveless paravertebral venous system carries tumor cells directly to vertebral bone marrow via retrograde flow during increased thoracic/abdominal pressure (coughing, straining, Valsalva), bypassing the caval system and pulmonary filter. This explains the vertebral predilection of prostate, breast, and pelvic tumors. In osteolytic metastasis, tumor cells secrete cytokines activating osteoclasts (RANKL, PTHrP, IL-6) — increased osteoclastic resorption causes bone matrix destruction. On MRI, T1 hypointensity results from tumor tissue replacing normal fatty marrow — the contrast between short T1 of fat protons and long T1 of tumor cells' high water content makes T1 the most sensitive sequence. STIR hyperintensity results from high cellular water content. Diffusion restriction reflects restricted water molecule movement from high cellularity — low ADC values (<1.0 x 10^-3 mm2/s) favor malignancy. In osteoblastic metastasis (prostate), tumor cells secrete osteoblast-stimulating factors creating sclerotic lesions.
On AP view or coronal CT, the two pedicles of the vertebra appear like 'owl eyes'. In metastatic pedicle destruction, the silhouette of one pedicle is lost creating the 'winking owl' appearance. This is a classic and easily recognized radiological sign of vertebral metastasis.
T1-weighted images show focal or diffuse hypointensity in the vertebral body. Against the hyperintense signal of normal fatty marrow, the low signal of tumor tissue creates sharp contrast. Focal type: circumscribed nodular hypointense focus. Diffuse type: homogeneous hypointensity throughout the vertebral body. Pedicle involvement is seen as T1 hypointensity and is a strong indicator of pathologic fracture.
Report Sentence
Hypointense bone marrow signal change in the vertebral body on T1-weighted sequence, suggesting replacement of fatty marrow by tumor tissue, consistent with metastatic involvement.
On diffusion-weighted imaging, metastatic vertebral lesion shows high signal (DWI hyperintense) and low signal on ADC map (diffusion restriction). ADC threshold is generally accepted as <1.0 x 10^-3 mm2/s. DWI/ADC provides 85-90% accuracy for differentiating benign edema (high ADC) from malignant infiltration (low ADC).
Report Sentence
Hyperintense signal on DWI and low signal on ADC map (diffusion restriction) in the vertebral body, indicating high cellularity and supporting metastatic involvement.
On CT, osteolytic metastasis appears as cortical destruction and hypodense lesion, while osteoblastic metastasis (prostate) appears as sclerotic hyperdense lesion. Pedicle destruction creates 'winking owl sign' on AP view. Pathologic fracture: convex posterior wall, cortical collapse, and soft tissue mass may accompany.
Report Sentence
Lytic bone destruction and cortical erosion in the vertebral body on CT, consistent with osteolytic metastasis.
Contrast-enhanced MRI evaluates epidural extension and spinal cord compression of vertebral metastasis. Epidural soft tissue mass shows enhancement and eliminates CSF signal. Billings scale grades epidural compression (Grade 0-3). MESCC requires urgent radiotherapy or surgical decompression.
Report Sentence
Epidural extension of vertebral metastasis and spinal cord compression on contrast-enhanced MRI; MESCC protocol should be applied.
FDG PET-CT is used for whole-body staging and treatment response assessment of vertebral metastases. Osteolytic metastases are generally FDG-avid while osteoblastic metastases (prostate) may show low FDG uptake — NaF PET is superior in this setting. Multifocal FDG uptake indicates metastatic extent.
Report Sentence
Increased FDG uptake (SUVmax: XX) in multiple vertebral bodies on PET-CT, consistent with metastatic bone involvement.
Criteria
Bone destruction dominant — lytic, hypodense lesion
Distinct Features
Most common type; breast, lung, kidney, thyroid origin; cortical destruction + hypodense lesion on CT; MRI T1 hypointense, T2/STIR hyperintense; FDG PET avid; high pathologic fracture risk
Criteria
New bone formation dominant — sclerotic, hyperdense lesion
Distinct Features
Most commonly from prostate; hyperdense sclerotic lesion on CT; MRI T1 AND T2 hypointense (calcium); FDG PET may show low uptake — NaF PET superior; elevated PSA is clinical clue
Criteria
Both lytic and blastic components — common from breast, lung, GI tract
Distinct Features
Heterogeneous density (mixture of lytic + sclerotic areas on CT); heterogeneous signal on MRI; pattern change may be seen during treatment response monitoring (lytic → blastic: treatment response)
Distinguishing Feature
In osteoporotic compression fracture, band-like edema, fluid cleft sign, normal pedicle signal, concave posterior wall, and absence of diffusion restriction (ADC >1.0) support benignity. In metastatic fracture, convex posterior wall, pedicle involvement, epidural mass, diffuse T1 hypointensity, and diffusion restriction (ADC <1.0) accompany as three cardinal signs of malignancy.
Distinguishing Feature
Vertebral hemangioma shows 'polka-dot sign' (thickened vertical trabeculae) on axial CT, hyperintense T1 signal (fat component), and hyperintense T2 signal on MRI. In metastasis, polka-dot sign is absent, T1 is hypointense (fat loss), and destructive pattern predominates.
Distinguishing Feature
In Schmorl's node, focal depression limited to end-plate, surrounding sclerotic rim, and absence of diffusion restriction are distinguishing. In metastasis, signal change extends beyond end-plate, with multiple level involvement, pedicle involvement, and diffusion restriction.
Urgency
urgentManagement
medicalBiopsy
NeededFollow-up
specialist-referralVertebral metastasis requires multidisciplinary approach. SINS (Spinal Instability Neoplastic Score): 0-6 stable (conservative), 7-12 potentially unstable (surgical consultation), 13-18 unstable (surgical). MESCC is an emergency — high-dose dexamethasone + radiotherapy or surgical decompression within 24 hours. In patients without known primary, biopsy is needed for histopathological diagnosis. Systemic treatment options include radiotherapy, bisphosphonates/denosumab, chemotherapy, immunotherapy. Whole-body MRI or PET-CT evaluates disease extent.
Vertebral metastasis is the most common spinal tumor and is one of the most frequent causes of back pain in patients with known malignancy. Assessment of pathologic fracture and cord compression is critical. SINS (Spinal Instability Neoplastic Score) is used for stability assessment. Cord compression requires urgent radiotherapy or surgical decompression. Whole-body MRI or PET-CT evaluates extent of disease.