Aspecte imagistice în fracturile vertebrale tumorale versus osteoporotice

Clinical history

A 74-year-old female patient with no significant medical history presented to our hospital (Fundeni Clinical Institute, Bucharest, Romania) with gradually increasing low back pain and functional impairment for one month.

Imaging findings

Non enhanced CT imaging demonstrated a compression fracture of L1 secondary to an osteolytic lesion involving the entire vertebral body, with cortical interruption (Figure 1 a, b). MRI of the lumbar spine revealed an L1 vertebral expansile mass, hypointense on T1-weighted images and hyperintense on STIR sequen­ces (Figure 1 c, d). Following contrast administration, the lesion showed intense, homogeneous enhancement, extending to the paravertebral and epidural space and posterior elements (Figure 1 e, f); additional lesions were identified in other lumbar and lower thoracic vertebrae. The findings were consistent with a tumoral fracture.

Discussion

The main differential diagnosis in our patient was an osteoporotic vertebral fracture, given her age and low-energy onset of symptoms. These are common in elderly patients, and typically involve multiple vertebral levels at onset⁽¹⁾.

Unlike malignant fractures, compression in osteoporotic fractures is usually symmetric on frontal views, whereas focal endplate fractures, as in this case (Figure 1b), should raise concern⁽²⁾. On CT and MRI, in acute osteoporotic fractures, fracture lines may be visible within the vertebral body or cortical bone, but there is no bone destruction (Figure 2) as seen in malignant fractures^(3,4). Retropulsion of the posterosuperior or inferoposterior vertebral corner into the spinal canal is a sign of benignity, and the posterior vertebral elements are typically preserved in osteoporotic fractures^(5,6). Intravertebral vacuum phenomenon (“vacuum cleft sign”) is almost pathognomonic for a benign fracture (Figure 3), and results from gas (mainly nitrogen) accumulating in the fracture line due to negative pressure, especially during spinal hyperextension^(2,7).

Tumoral fractures are often associated with paravertebral or epidural masses, indicating direct tumor extension; on axial images, the ventral extradural space may appear bilobed (“curtain sign”) – Figure 1f^(4,6).

Bone marrow contains 40-80% fat, appearing hyperintense on T1-weighted images⁽⁸⁾. In chronic osteoporotic fractures (>3 months), T1 hyperintensity is usually preserved^(4,6). In recent osteoporotic fractures, vertebral edema appears as low T1 and high T2 signal beneath the collapsed plateau, with indistinct margins and gradually decreasing intensity away from the fracture line^(2,9).

Bone tumor infiltration appears as low signal on T1-weighted images, equal to or lower than that of the intervertebral disc or paravertebral muscles⁽¹⁰⁾. On fluid-sensitive sequences, marrow is moderately to markedly hyperintense. Tumor-related fractures show heterogeneous T1/T2 signal, may enhance post-contrast, and often extend beyond the fracture site^(2,4,6).

Hypointense band on all sequences indicates the fracture line in osteoporotic vertebrae. The “fluid sign” (T1 hypointense, T2 hyperintense focal, linear, or triangular area) appears in acute fractures, reflecting fluid replacing air in the vacuum cleft^(2,4).

Conclusions

Differentiating tumor-related from osteoporotic vertebral fractures remains challenging, particularly in elderly patients presenting after minor trauma. CT and MRI play a crucial role in identifying imaging features suggestive of malignancy, allowing the accurate diagno­sis and the appropriate therapeutic management.   

Corresponding author: Ioana G. Lupescu E-mail: ioana.lupescu@umfcd.ro

Conflict of interest: none declared.

Financial support: none declared.

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