Should SPECT-CT replace SPECT for the evaluation of equivocal bone scan lesions in patients with underlying...

Bone scintigraphy is used extensively in evaluating metastatic disease. There are currently no clear recommendations for the use of single photon emission computed tomography (SPECT)/CT in metastatic bone disease. Given its limited availability there is a need to identify the clinical indications for which SPECT/CT is clearly beneficial in influencing patient care and outcome.

Forty-two patients with equivocal lesions on planar scintigraphy were recruited and underwent SPECT/CT imaging. On reading of SPECT alone and then SPECT/CT, lesions were classified as malignant, benign or equivocal. Follow-up clinical information, radiological studies and/or bone scans were used as a gold standard. SPECT and SPECT/CT were compared in terms of the number of equivocal findings and accuracy on a patient-wise and lesion-wise basis.

Forty-two patients with 189 skeletal lesions were examined. There was a diverse variety of primary tumours, with the majority being breast (n=22) and prostate cancer (n=8). SPECT/CT resulted in a significant reduction in the proportion of patients (48-14%, P=0.0015) and lesions (31-9%, P<0.0001) with equivocal findings. The overall accuracy of SPECT/CT was significantly higher on both a patient-wise (52-79%, P=0.0026) and lesion-wise basis (67-92%, P<0.0001).

SPECT/CT significantly outperforms SPECT alone for the interpretation of skeletal lesions in patients undergoing bone scanning for metastases. When available SPECT/CT is indicated in patients in whom correct classification of equivocal lesions is expected to alter the patient's management.