Magnetic resonance imaging versus radionuclide scintigraphy in screening for bone metastases

AIM: To determine the frequency of isolated, asymptomatic metastases of the peripheral skeleton in patients with breast and prostate cancer. METHODS: A retrospective review was performed of staging skeletal scintigra ms, Patients with hot spots in the peripheral skeleton in the absence of co nvincing evidence of metastatic disease in the axial skeleton were followed -up to determine the nature of the peripheral lesion(s) based on other imag ing modalities, serial imaging or biopsy, and to determine if the lesion(s) had been symptomatic at the time of the scintigram, SUBJECTS: 200 patients with histologically proven carcinomas of the breast or prostate. RESULTS: Four patients (2%) had isolated metastatic involvement of the peri pheral skeleton, and would, therefore, have been wrongly staged by a magnet ic resonance 'marrow screen' of the axial skeleton. However, in three of th ese patients the lesions were painful, prompting diagnostic plain radiograp hs independent of the scintigraphic findings. Twelve patients (6%) had isol ated scintigraphic abnormalities of the peripheral skeleton suggestive of m etastatic disease but which on further investigation mere shown to be benig n lesions. CONCLUSION: A limited magnetic resonance (MR) 'marrow screen' confined to t he axial skeleton would not result in any significant loss of accuracy in s taging patients with breast and prostate carcinoma compared with skeletal s cintigraphy, Given the proven increased sensitivity of MR over skeletal sci ntigraphy in the detection of bone metastases, and the additional informati on MR provides, it is likely to provide a more accurate basis for managemen t.