Can a computed tomography (CT) scan of the spine determine if a vertebral compression fracture is a pathological fracture?

Can CT Spine Determine if a Vertebral Compression Fracture is Pathological?

CT spine has limited but useful capability to suggest pathological fractures through specific morphologic features, but MRI is imperative and superior for definitively distinguishing benign from malignant vertebral compression fractures. 1

CT's Diagnostic Capabilities for Pathological Fractures

What CT Can Show

CT spine without contrast can evaluate osseous integrity and identify several features suggestive of pathological fracture: 1

• Cortical destruction of the anterolateral and/or posterior vertebral body (100% accuracy for malignancy) 2
• Cancellous bone destruction within the vertebral body (97.4% accuracy for malignancy) 2
• Endplate destruction 2
• Pedicle involvement or destruction 2
• Paraspinal soft tissue mass 2
• Epidural mass (though poorly depicted compared to MRI) 1

High-resolution multidetector CT with thin-slice (1mm) axial images and multiplanar reconstructions provides sufficient diagnostic ability for clinical differentiation between benign and malignant fractures based on these morphologic features. 2

CT's Limitations

CT is fundamentally limited because intradural and spinal cord pathologies are poorly depicted, and it cannot assess bone marrow signal abnormalities that are critical for distinguishing pathological from benign fractures. 1

• CT cannot detect early metastases localized completely within the bone marrow cavity 1
• CT cannot reliably determine fracture acuity or demonstrate bone marrow edema 3, 4
• CT cannot assess the degree of thecal sac or cord compression as effectively as MRI 1
• CT cannot evaluate epidural extension, paraspinal extension, or vascularity with the same sensitivity and specificity as MRI 1

Why MRI is Imperative

MRI is imperative for assessing vertebral compression fractures in patients with history of malignancy or atypical clinical features, as it can definitively differentiate benign from malignant fractures. 1

MRI's Superior Features

• Visualization of abnormal marrow signal, convex posterior vertebral body border, and extension into posterior elements are suggestive of pathologic fracture 1
• Detection of bone marrow edema determines fracture acuity, which CT cannot reliably assess 3, 4
• Intraosseous disease is best delineated on noncontrast MRI sequences (T1-weighted and STIR) 1
• Contrast-enhanced MRI helps delineate epidural, foraminal, paraspinal, and intrathecal disease extension 1

When to Use MRI Without and With Contrast

Add contrast when clinical suspicion exists for: 1, 3

• Underlying malignancy or metastatic disease
• Infection or epidural abscess
• Inflammatory processes
• Immunosuppression

Clinical Algorithm

Step 1: Assess for Red Flags 1, 3

• History of cancer
• Unexplained weight loss
• Fever
• Immunosuppression
• IV drug use

Step 2: Choose Imaging Based on Clinical Context

If red flags present: Order MRI spine without and with IV contrast as the initial study 1, 3

If no red flags but fracture identified on radiographs/CT: Order MRI spine without IV contrast to determine fracture acuity and distinguish benign from pathological etiology 3

If CT already performed and shows concerning features: Proceed directly to MRI, as CT findings of cortical destruction, cancellous bone destruction, pedicle involvement, or soft tissue mass warrant definitive characterization 2

Step 3: Consider Biopsy if Ambiguous

If imaging features remain ambiguous after MRI, image-guided biopsy should be performed to verify etiology. 1

Important Caveats

• At least half of bone must be eroded before changes are noticeable on radiographs or CT, making these modalities insensitive for early pathological processes 1
• Osteoporotic fractures can occur in patients with known malignancy, so the presence of cancer history alone does not confirm pathological etiology—imaging differentiation is essential 1
• CT with IV contrast adds minimal value for distinguishing pathological from benign fractures compared to noncontrast CT, as the key discriminators are morphologic features visible without contrast 1
• Whole-body FDG-PET/CT can distinguish benign versus malignant compression fractures but is not an initial imaging study 1