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SPECT/CT of sentinel lymph nodes more sensitive than lymphoscintigraphy

By 14th August 2014No Comments

Startling data from an international multi-center trial and presented at the recent 2014 annual meeting of the Society of Nuclear Medicine and Molecular Imaging (SNMMI) provide growing evidence that sentinel node imaging is more effectively carried out with (SPECT/CT) hybrid functional imaging than with lymphoscintigraphy. This conclusion is valid for a range of cancers displaying a variety of lymphatic drainage types associated with melanoma; breast carcinoma; and malignancies of the pelvis, such as prostate and cervical cancer.

Molecular imaging of sentinel lymph nodes can provide a surgical map that can improve a patient’s chances of becoming cancer free. Lymph node imaging is important in the context of surgical resection, since cancerous cells spread first to the sentinel lymph nodes, before navigating the bloodstream and developing new malignancies elsewhere in the body. “We found significantly more sentinel lymph node involvement with SPECT/CT, which altered surgical planning for many of our patients—a finding that was repeated across all malignancies and clinical institutions,” said Dr T. Pascual, co-author of the study and a research scientist from the section of nuclear medicine and diagnostic imaging and division of human health of the International Atomic Energy Agency in Vienna, Austria. “These results could potentially affect new clinical practice and shape appropriate use of SPECT/CT imaging for patients selected for surgery.”

The study findings showed that in breast cancer SPECT/CT imaging detected 13 percent more cancerous sentinel nodes—2,165 nodes compared with 1,892 using planar lymphoscintigraphy. The hybrid SPECT system also detected 11.5 percent more sentinel nodes when imaging for melanoma. As for pelvic cancer, 29.2 percent more nodes were imaged using SPECT/CT than with planar imaging.

Changes in surgical planning as dictated by SPECT/CT results were substantial—16.9 percent of breast cancer surgeries underwent a change in management, 37 percent of surgeries for melanoma changed and 64.1 percent of surgical plans for pelvic cancer were changed due to detection of additional sentinel nodes. Calculated mismatch between sentinel nodes and lymphatic territories using the two imaging systems was gauged at 17 percent for breast carcinoma, 11.2 percent for melanoma and 50 percent for pelvic imaging. The significantly higher mismatch in pelvic tumors was thought to be due to relatively deeper lymphatic drainage and location of pelvic sentinel nodes.