Comparison of whole-body MRI and bone scintigraphy in the detection of bone metastases in renal cancer

This study aims to compare the sensitivity of whole-body MRI with bone scintigraphy in the detection of bone metastases in patients with renal cancer. A prospective study was carried out in 47 patients with renal cancer (mean age 62 years, range 29-79 years). All patients had assessment of the skeleton with whole-body bone scintigraphy (with technetium-99m methylene diphosphonate) and whole-body MRI (coronal T, weighted and short tau inversion recovery sequences). The number and sites of bony metastases were assessed on each imaging investigation independently. Sites of extra-osseous metastasis on MRI were also noted. The imaging findings were correlated with other imaging modalities and follow-up. 15 patients (32%) had bone metastases at 34 different sites. Both scintigraphy and MRI were highly specific (94% and 97%, respectively), but the sensitivity of MRI (94%) was superior (P=0.007) to that of scintigraphy (62%). MRI identified more metastases in the spine and appendicular skeleton, whereas scintigraphy showed more lesions in the skull/facial and thoracic bones. MRI identified extra-osseous metastases in 33 patients (70%), these were mainly lung and retroperitoneal in site. Whole-body MRI is a more sensitive method for detection of bone metastases in renal cancer than bone scintigraphy, and also allows the assessment of soft-tissue disease.