Comparison between planar, SPECT and SPECT/computed tomography systems in 99mTc- nanocolloid sentinel lymph node imaging: phantom design and clinical investigations.

PURPOSE

It was aimed to examine the performance of planar, SPECT and SPECT/CT in lymph nodes detection of breast cancer.

MATERIALS AND METHODS

In-house made phantom was immersed in water-filled container. Disparate activities were injected into spheres emulating breast tumour (1.5 cm), and adjacent lymph nodes (1, 0.5 and 0.25 cm). Planar, SPECT and SPECT/CT scans were made at depths of 1, 3, 5, 7 and 9 cm. Rose Criteria was employed to investigate the detectability in planar imaging, and contrast to noise ratios (CNRs) were used in SPECT and SPECT/CT images. SPECT and SPECT/CT of 20 patients were randomly incorporated in the current study.

RESULTS

CNR values from planar images at 1 cm depth for the simulated nodes of 1, 0.5and 0.25 cm were 36, 18 and 17, respectively. Whereas, those from SPECT/CT were 94.5, 63.3 and 20.9, repectively. CNRs from SPECT were lower than SPECT/CT in order of 60.1, 41.8 and 17.1 at the same depth. At 9 cm, CNR values of 1, 0.5 and 0.25 cm from the planar images were 14, 6 and 5, respectively. While CNR values from SPECT were higher as 53.6, 38.0, and 14.9, respectively, and the greatest CNRs were in SPECT/CT as 85.7, 55.8, and 19.1, repectively.

CONCLUSION

The CNR values in SPECT/CT were 1.5- and 3.5-folds higher than SPECT and planar imaging at depth range 1-9 cm. The patients study exhibited larger SPECT/CT CNRs over SPECT as great as 1.6-fold.