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Usefulness of Spect-CT Image Fusion in Degenerative Pathology of the Spine 2005

General Spine

Gonzalo Ucros, MD
Sonia V Bermudez, MD, Non ASSR Member
Anibal J Morillo, MD, Non ASSR Member
Monica D Ocampo, MD, Non ASSR Member
Andres . Rodriguez, MD, Non ASSR Member

Purpose

To compare CT and SPECT bone scintigraphy evaluated independenty with SPECT- CT fusion images in patients with known degenerative spinal pathology.

Methods & Materials

Seventeen patients with known degenerative spinal disease were evaluated with initial bone scintigrams performed with a dual-head coincidence gamma camera, with an elliptical orbit trajectory obtaining 128 images on a 128 x 128 matrix. Axial, sagittal, coronal and 3D reconstructions were obtained. The images were evaluated independently by a nuclear medicine specialist.

Within a 24- hour period, the patients underwent helical CT studies (3-4mm axial slice acquisition, 2mm reconstructed slice thickness, sagittal and coronal multiplanar reconstructions). The study was independently evaluated by a radiologist.

Finally, multimodality image fusion software (ESoft Siemens- Erlangen, Germany) was used to merge the CT and SPECT studies and a final interpretation of the combined images was obtained.

Results

18 CT scans and bone scintigraphy images were obtained for 17 patients. The results of the bone scintigraphy and CT scans were in agreement in 9 pairs of studies (50%). In these studies image fusion did not provide additional information on the location or extension of the lesions.
In 6 of the study pairs (33%), the information obtained was not in agreement between scintigraphy and CT studies. In these cases image fusion helped establish the precise localization of the lesion with the greatest uptake.
Image fusion proved helpful in 3 studies (16%) where scintigraphy and CT findings were in agreement but each provided additional information. In these cases image fusion helped define the most significant findings.

Conclusion

The use of CT- SPECT fusion images increases the diagnostic accuracy of degenerative joint disease to a greater degree than CT and SPECT alone scintigraphy with SPECT or CT alone, in particular in facetary arthrosis.
In 33% of cases the interpretation of CT-SPECT fusion images altered the therapeutic choices for the patient, allowing for a more precise localization of the most metabolically active lesion.

References

1. AJR 2004; 182: 1571- 1577
2. Radiology 2001; 218: 163- 171
3. Radiographics 2004; 24: 1411- 1431
4. The British Journal of Radiology 2002; 75: S 24- S 30