18F-fluorodeoxyglucose specimen-positron emission mammography delineates tumour extension in breast-conserving surgery: Preliminary results

Differences in Re-excision Rates for Breast-Conserving Surgery Using Intraoperative 2D Versus 3D Tomosynthesis Specimen Radiograph

BACKGROUND

Intraoperative specimen radiographs performed during breast conservation surgery for cancer reduces the need for re-excision for positive margins. We studied 2D versus 3D image-guided cavity margin excision and compared it to final pathology and need for additional surgery.

METHODS

We conducted a retrospective review of 657 breast-conserving operations performed for cancer from 2013 to 2018. Procedures were performed by four surgeons at a single tertiary institution with access intraoperatively to 2D and 3D radiographs. Data collected included demographics, intraoperative margin assessment, final pathology, and re-excision rates.

RESULTS

A total of 466 patients had 2D and 191 had 3D specimen imaging. The 2D group had a lower mean age and a higher body mass index and proportion of minority patients than the 3D group (P < 0.01). In the 3D group, there was a higher percentage of patients with mammographically denser breasts (P < 0.06); 58% of patients in the 3D group had additional imaging-directed cavity margins excised versus 32% of patients in the 2D group (P < 0.01). In the 2D group, 44 patients (9%) had positive final margins versus 8 patients (4%) in the 3D group (P = 0.02). No difference was found on total volume of excision (P = 0.56). The re-excision rate for the 2D group was 11% versus 5% for the 3D group (P = 0.02; adjusted odds ratio = 0.41, 95% confidence interval 0.19-0.86).

CONCLUSIONS

Re-excision rates using both modalities are low. A lower re-excision rate is independently associated with 3D tomosynthesis. This allows surgeons to excise additional margins at the index operation, decreasing reoperations and anxiety/costs for patients.

Newly-Developed Positron Emission Mammography (PEM) Device for the Detection of Small Breast Cancer

Positron emission mammography (PEM) has higher detection sensitivity for breast cancer compared with whole-body positron emission tomography (PET) due to higher spatial resolution. We have developed a new PEM device with high resolution over a wide field of view. This PEM device comprises novel scintillation crystals, praseodymium-doped lutetium aluminum garnet (Pr:LuAG). In the present study, the clinical use of the newly developed PEM for the detection of small breast cancer was compared with that of the conventional PET-computed tomography (PET/CT). Eighty-two patients with breast cancer less than 20 mm (UICC T1) participated in this study, including 23 patients with T1a or T1b breast cancer (less than 10 mm). Histologically-proved lesions were examined by PET/CT and PEM on the same day after injection of [¹⁸F]fluoro-2-deoxy-2-fluoro-D-glucose ([¹⁸F]FDG), a marker of glycolytic activity. The newly developed PEM showed better sensitivity of cancer detection compared with PET/CT especially in case of the small T1a or T1b lesions. Moreover, when the conventional PET/CT and new PEM were combined, the detection sensitivity with [¹⁸F]FDG molecular imaging for T1 (N = 82) and T1a plus T1b breast cancer (N = 23) were 90% and 70%, respectively. The uptake of [¹⁸F]FDG was proportional to the histological malignancy of breast cancer. Using the newly-developed PEM with [¹⁸F]FDG, we are able to identify and characterize exactly the small breast tumors less than 10 mm in combination with the conventional PET/CT. These data indicate that PEM and PET/CT are synergic and complementary for the detection of small breast cancer.