Whole-body magnetic resonance imaging for detecting bone metastases: comparison with bone scintigraphy

The aim of the study was to assess the reliability of whole-body magnetic resonance imaging (WB-MRI) in detecting skeletal metastasis and to compare the results with those of bone scintigraphy (BS). Thirty-three patients (21 women, 12 men, median age 58 years, range 27-78) were enrolled. Histological proof of malignancy was obtained in all cases. The primary tumour was unknown in 1 patient. BS and WB-MRI were performed as staging procedures in 15 patients, during the follow-up in 6 and to investigate pain in 9 and neurological symptoms in 3. Bone metastases were recorded for 8 different skeletal segments (ribs, skull, cervicothoracic spine, lumbosacral spine, clavicle-scapula-sternum, pelvis, upper extremities and lower extremities) in all patients, for a total of 264 examined areas. Bone metastases were detected in 18 patients (55%). In 15/33 patients, WB-MRI and BS were concordantly negative. BS revealed focal metastatic uptake in 72%, whereas WB-MRI was positive in 89%. Results differed in seven patients. WB-MRI was positive but BS was negative in five cases. Two patients with negative WB-MRI had focal and intense uptake in the ribs on BS. Out of 264 examined areas, bone metastases were detected in 34 (13%). WB-MRI revealed tumour spread in 26/34 areas (76%) and BS in 21/34 areas only (62%). WB-MRI is a reliable method for screening patients with suspected skeletal metastases, although BS still remains a useful tool. WB-MRI is also advantageous because it reveals extraskeletal and soft tissue metastases.