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Intramedullary spinal cord metastases: visibility on PET and correlation with MRI features
P M Mostardi1, F E Diehn, J B Rykken
1Mayo Medical School.
Background And Purpose:
Studies systematically evaluating the detection of intramedullary spinal cord metastasis with PET are lacking. Our purpose was to evaluate the visibility of intramedullary spinal cord metastasis on PET in a single institutional series and to correlate PET and MR imaging features.
Materials And Methods:
Patients were included if pretreatment MR imaging identifying an intramedullary spinal cord metastasis and an [(18)F] FDG-PET examination near the time of MR imaging were available. PET examinations were retrospectively reviewed, with reviewers blinded and then unblinded to the PET report and MR imaging findings. PET intramedullary spinal cord metastasis features were compared with and correlated with previously analyzed MR imaging lesion characteristics. Original clinical PET reports were reviewed.
Results:
The final study sample was 10 PET examinations in 10 patients with 13 intramedullary spinal cord metastases. In 7 (70%) patients, retrospective blinded review demonstrated convincing evidence of 10 (77%) intramedullary spinal cord metastases. Three MR imaging features correlated with intramedullary spinal cord metastases being visible on PET compared with those nonvisible, respectively: larger lesion enhancement size: mean size: 32.1 mm versus 6.0 mm (P = .038); larger longitudinal extent of T2 signal abnormality: mean 5.6 versus 1.0 segments (P = .0081); and larger ratio of extent of T2 signal abnormality to contrast enhancement: 3.8 versus 1.0 (P = .0069). Intramedullary spinal cord metastasis was confidently reported clinically in 2 (20%) patients, accounting for 5 (38%) intramedullary spinal cord metastases.
Conclusions:
Most intramedullary spinal cord metastases can be detected on PET when performed near the time of pretreatment MR imaging. However, intramedullary spinal cord metastases may not be clinically reported on PET. Larger lesions with more edema are more likely to be visible. The spinal cord should be specifically and carefully assessed on PET for evidence of intramedullary spinal cord metastases to provide timely diagnosis.
Insights
Positron emission tomography (PET) can detect most intramedullary spinal cord metastases when performed with MR imaging. However, these metastases may be missed in clinical PET reports, highlighting the need for careful spinal cord assessment.
Area of Science:
- Oncology
- Radiology
- Nuclear Medicine
Background:
- Systematic evaluations of PET for intramedullary spinal cord metastasis detection are limited.
- Intramedullary spinal cord metastasis detection is crucial for timely diagnosis and treatment.
Purpose of the Study:
- To evaluate the visibility of intramedullary spinal cord metastasis on PET scans.
- To correlate PET findings with MR imaging features of these metastases.
Main Methods:
- Retrospective review of 10 PET examinations in 10 patients with confirmed intramedullary spinal cord metastasis via MR imaging.
- PET scans were reviewed by blinded and unblinded readers.
- PET findings were correlated with MR imaging characteristics.
Main Results:
- PET detected 77% of intramedullary spinal cord metastases in a blinded review.
- Larger lesion size, greater T2 signal abnormality extent, and a higher ratio of T2 abnormality to enhancement on MR imaging correlated with PET visibility.
- Clinical PET reports only identified 38% of the metastases.
Conclusions:
- PET can detect most intramedullary spinal cord metastases when performed concurrently with MR imaging.
- Larger lesions with increased edema are more likely to be visible on PET.
- Careful, specific assessment of the spinal cord on PET is essential for accurate diagnosis.
