The role of magnetic resonance imaging and positron emission tomography-computed tomography combined in differentiating benign from malignant lesions contributing to vertebral compression fractures

BACKGROUND: Obtaining tissue confirmation of the underlying pathology is the gold standard for establishing the etiology of nontraumatic vertebral compression fractures. However, newer investigative modalities such as the magnetic resonance imaging (MRI) and positron emission tomography-computed tomography (PET-CT) combined potentially offer the ability to distinguish between benign and malignant lesions, thereby circumventing the need for invasive tissue diagnostic/biopsy procedures. METHODS: Twenty-four patients with nontraumatic, spontaneous vertebral compression fractures were prospectively studied. After clinical evaluation, all patients underwent MRI (with/without contrast) focusing on the spinal lesion, followed by whole-body PET-CT. This was followed by fine needle aspiration cytology (FNAC) of the lesion to confirm the diagnosis. The sensitivity and specificity of MRI and PET-CT studies were calculated for benign vs. malignant lesions. RESULTS: The sensitivity/specificity of MRI for benign lesions were 78.57%/90%, while the sensitivity/specificity values of PET-CT for benign disease were 92.8%/90% respectively. Alternatively, the sensitivity/specificity of MRI for malignant lesions were 90%/78.57%, while the sensitivity/specificity of PET-CT for malignant disease were 90%/92.8%, respectively. Furthermore, the sensitivity for diagnosing malignant lesions utilizing both studies together was 100%, but the algorithm was not specific. Additionally, the specificity for MRI and PET-CT combined was 100% for benign lesions. PET-CT also helped in monitoring responses to empirical antitubercular treatment (ATT) therapy. Of interest, FNAC was inconclusive in four cases in which PET-CT findings helped further in either obtaining a tissue diagnosis from another location or institution of empirical therapy in suspected cases of tuberculosis. CONCLUSIONS: The specificity for MRI and PET-CT combined was 100% for benign lesions. Unfortunately, the specificity for MRI and PET-CT combined was not 100% for malignant vertebral lesions, though it was sensitive. The PET-CT scan was an extremely useful tool when FNAC from the affected site proved inconclusive. It gave additional information regarding the overall extent of disease, while identifying other locations amenable to FNAC. Furthermore, in countries where tuberculosis is endemic, the empirical response to ATT therapy could be monitored utilizing PET-CT.