Presurgical SPECT/CT Imaging for Breast Cancer Reveals More Tumors Than Lymphoscintigraphy

Surprising findings from an international multicenter trial provide mounting evidence that sentinel node imaging is more effectively performed with hybrid functional imaging using single photon emission computed tomography/computed tomography (SPECT/CT) than with another molecular imaging technique, the current standard, lymphoscintigraphy.

This conclusion was reached after imaging a range of tumors displaying a variety of lymphatic drainage types associated with melanoma, an aggressive skin cancer; breast carcinoma; and malignancies of the pelvis, such as prostate and cervical cancer.

Lymph node imaging is an indispensable tool in the context of surgical resection, because cancer metastasizes first to the lymph nodes, specifically the sentinel lymph nodes, before moving through the bloodstream and developing new tumors elsewhere in the body. Molecular imaging of these sentinel nodes provides a surgical map that can improve a patient’s likelihood of becoming cancer-free.

“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 Thomas N.B. Pascual, MD, coauthor 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 (IAEA; Vienna, Austria). “These results could potentially inform new clinical practice and shape appropriate use of SPECT/CT imaging for patients selected for surgery.”

The study’s findings were presented at the Society of Nuclear Medicine and Molecular Imaging’s 2014 annual meeting, held June 7–11, 2014, in St. Louis (MO, USA). Study findings revealed that SPECT/CT breast cancer imaging captured 13% more cancerous sentinel nodes—2,165 nodes versus 1,892 using planar lymphoscintigraphy. The hybrid SPECT system also captured 11.5% more sentinel nodes when imaging for melanoma, with 602 versus 532 nodes identified. Furthermore, 29.2% more nodes were imaged using SPECT/CT to detect pelvic cancer—195 nodes found versus 138 with planar imaging.

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

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International Atomic Energy Agency