Fast spin echo MRI and bone scintigraphy in the detection of skeletal metastases

Abstract

Standard Spin Echo (SE) magnetic resonance imaging (MRI) is known to be a very sensitive method for the detection of bone metastases and in comparison to skeletal scintigraphy, MRI detects more lesions when field of view includes the area of suspicion. However, only with the introduction of new fast SE sequences, have MRI protocols, for the detection of metastases, become rapid enough to make it a potential screening procedure for metastatic disease. Twenty-one patients with a suspicion of carcinomatous bone metastases were evaluated with both conventional T1 weighted (T1w), T2 weighted (T2w) and fast T2w SE (FSE) sequences (thoraco-lumbar spine and pelvis) and whole body bone scintigraphy. Conventional and fast T2w SE sequences detected the same number of lesions while bone scintigraphy detected only 70% of the lesions seen on MRI. However, more importantly, in 11 of the 21 patients bone scintigraphy detected lesions outside the MR field of view, lying in the ribs, skull, scapulae and extremities and in 4 of them, MRI was negative. Our results suggest first that fast SE MRI can replace conventional SE MRI when looking for carcinomatous bone metastases in the axial skeleton, with the advantage of a four to six times reduced acquisition time for fast T2w sequences. However, the limited field of view still limits the usefulness of MRI and whole body bone scintigraphy remains the screening modality for bone metastases. Fast MRI plays an important complementary role.