Image guidance for FNAC of vertebral lytic lesions - USG or CT?

Aim: To assess the role of sonography and CT for guiding FNACs of vertebral lytic lesions and to determine the type of lesions amenable for sonographically guided biopsies. Material and methods: Prospective study was carried out incorporating 65 patients with vertebral lytic lesions, out of which 27 patients were taken up for FNAC under USG guidance, after review of available radiology. Rest 38 patients underwent FNAC under CT guidance. FNAC was taken from bone (n=19) or associated extra osseous soft tissue component (n=46). FNAC findings were categorized as group I = positive, when aetiology whether infective/neoplastic could be established on smear/culture, Group II = adequate aspirate but inconclusive diagnosis and Group III = inadequate aspirate. Results: Posterior element involvement was seen in 41.5% patients (n=27) out of which USG guided FNAC was performed in 74% patients (n=20) while CT guided FNAC was performed in rest 25.9% patients (n=7). In patients with sparing of posterior elements (n=38) USG guided FNAC was possible in 18.4% patients (n=7) of which 5 lesions were in the cervical spine and 2 in the lumbar region. Rest of the 81.6% patients (n=31) were subjected to CT guided FNAC. US guided FNAC was possible in 90% of cervical vertebral lesions. US guided FNAC yielded adequate material and definite diagnosis in 92.5% patients (n=25/27). CT guided FNAC yielded adequate material in 76.3% (n=29/38). Conclusion: USG guided FNAC is an inexpensive, readily available and non-ionizing modality for FNAC of vertebral lytic lesions. It is specially useful in patients with lesions in cervical spine. In patients with thoracic lumbar and sacral lesions it is feasible in presence of posterior element involvement with sonographically visualized extraosseous soft tissue component. If patient selection is carefully made using the proposed algorithm it has a diagnostic yield of almost 97.5%.