Breast Cancer Axillary Lymph Node Metastasis Detection by a High-Resolution Dedicated Breast Camera: A Comparative Study with SPECT and Pinhole SPECT

We evaluated the usefulness of ^99mTc-tetrofosmin planar scintigraphy acquired with a high-resolution (HR) dedicated breast camera in comparison with conventional single-photon emission computed tomography (SPECT) and pinhole-SPECT (P-SPECT) in breast cancer (BC) axillary lymph node metastasis detection in a consecutive series of 76 BC patients, 28 of whom had axillary lymph node metastases, including 9 positive at clinical examination. HR planar scintigraphy was true positive in only 7 patients with >3 palpable metastases (sensitivity: 25%), while SPECT was true positive in 23 of 28 cases (sensitivity: 82.1%) and P-SPECT in 25 of 28 (sensitivity: 89.3%). SPECT was false negative in 5 patients with nonpalpable ≤3 nodes, including 2 with one micrometastatic node, while P-SPECT was false negative in the latter 2 cases, and in another of the cases, false negative at SPECT with one macrometastatic node. Neither planar nor SPECT had false-positive findings (specificity: 100%), while P-SPECT had two (specificity: 95.8%). P-SPECT presented the best resolution in showing the metastatic nodes and was the only procedure able to define the number of involved nodes, thus delivering important prognostic information. HR planar scintigraphy appears an ineffective diagnostic tool in BC axillary lymph node metastasis detection, only succeeding in identifying palpable and >3 metastatic nodes. SPECT should be preferred, significantly improving the sensitivity of planar scintigraphy, especially when using a pinhole collimator.