The most important prognostic factor in breast (B) cancer (C) is axillary (A) lymph (L) node (N) status, and virtually all patients with BC undergo ALN dissection to assess N involvement. The aim of this study was to evaluate the accuracy of planar and tomographic Tc-99m tetrofosmin scintigraphy in the detection of ALN involvement in BC. A group of 85 female patients (age range: 31-82 years) with 87 BCs were studied before surgery. Three planar images, right and left prone lateral and supine anterior thoracic views, and 360° supine thoracic single photon emission tomography (SPET) were acquired after Tc-99m tetrofosmin injection (740 MBq i.v.). ALN status was evaluated by histological exam after A dissection: metastatic ALN involvement was proved in 31 out of 87 cases. Sensitivity was 87.1% (27/31) for SPET and 61.3% (19/31) for planar images (p<0.01); specificity was 92.9% (52/56) and 94.6% (53/56), respectively, with a global accuracy of 90.8% (79/87) for SPET and 82.8% (72/87) for planar imaging (p<0.05). Sensitivity rose from 75% in non-palpable Ns to 94.7% in palpable ones for SPET, and from 41.7 to 73.7% for planar scans. SPET was positive in 17/18 (94.4%) patients with >3 metastatic Ns and in 10/13 (76.9%) with ≤3 involved Ns, whereas planar images were positive in 14/18 (77.8%) and in 5/13 (38.5%) cases, respectively. In conclusion, our findings indicate that Tc-99m tetrofosmin scintigraphy is useful in the presurgical detection of ALN metastases in BC, with SPET more accurate than conventional planar images, thus suggesting its more frequent use in scintimammography; moreover, the total number of histologically involved Ns can affect the scintigraphic results.

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