Factors influencing visualization of vertebral metastases on MR imaging versus bone scintigraphy.
OBJECTIVE
The purpose of this study was to investigate whether the location and size of vertebral body metastases influence the difference in detection rates between MR imaging and bone scintigraphy.


METHODS
We retrospectively evaluated the vertebral body lesions detected on MR imaging in 74 patients with known widely disseminated metastatic disease. Three radiologists independently reviewed the MR images and bone scintigraphs. MR imaging findings included lesion size and its spatial relationship to the bony cortex (intramedullary, subcortical, and transcortical) and results were correlated with those of planar technetium 99m bone scintigraphy.


RESULTS
Findings on bone scans were negative for all intramedullary lesions without cortical involvement shown on MR imaging, regardless of their size. Findings on bone scans (71.3% for transcortical and 33.8% for subcortical) were frequently positive for lesions with cortical involvement (trans- or subcortical), and the probability of positive findings on bone scans was also influenced by the lesion size. Statistical analysis showed a positive correlation among cortical involvement, lesion size, and positive findings on bone scintigraphy (p < 0.0001).


CONCLUSIONS
Location (the presence of cortical bone involvement on MR imaging) and size of the vertebral body metastases appear to be important contributing factors to the difference in detection rates between MR imaging and bone scintigraphy. Cortical involvement is likely the cause of positive findings on bone scans. Early vertebral metastases tend to be small and located in the medullary cavity without cortical involvement, and therefore, findings may be positive on MR images but negative on bone scans.
Taoka
T
T
Department of Radiology, Magnetic Resonance Imaging Center, University of Iowa College of Medicine, 200 Hawkins Dr., Iowa City, IA 52242, USA.
Mayr
N A
NA
Lee
H J
HJ
Yuh
W T
WT
Simonson
T M
TM
Rezai
K
K
Berbaum
K S
KS
D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D013125:Spinal Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000556:secondary*; D013669:Technetium Tc 99m Medronate; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging* / Q000473:pathology
D019275:Radiopharmaceuticals; D013669:Technetium Tc 99m Medronate