The Preoperative Role of Breast-specific Gamma Imaging for the Breast Cancer Patients: In Comparison with Conventional Imaging Modality

KSNM60 in Clinical Nuclear Oncology

Since the foundation of the Korean Society of Nuclear Medicine in 1961, clinical nuclear oncology has been a major part of clinical nuclear medicine in Korea. There are several important events for the development of clinical nuclear oncology in Korea. First, a scintillating type gamma camera was adopted in 1969, which enabled to perform modern oncological gamma imaging. Second, Tc-99 m generator was imported to Korea since 1979, which promoted the wide clinical use of gamma camera imaging by using various kinds of Tc-99 m labeled radiopharmaceuticals. Third, a gamma camera with single photon emission tomography (SPECT) capability was first installed in 1980, which has been used for various kinds of tumor SPECT imaging. Fourth, in 1994, clinical positron emission tomography (PET) scanner and cyclotron with a production of F-18 fluorodeoxyglucose were first installed in Korea. Fifth, Korean Board of Nuclear Medicine was established in 1995, which contributed in the education and manpower training of dedicated nuclear medicine physicians in Korea. Finally, an integrated PET/CT scanner was first installed in 2002. Since that, PET/CT imaging has been a major imaging tool in clinical nuclear oncology in Korea. In this review, a brief history of clinical nuclear oncology in Korea is described.

Diagnostic Performance of Breast-Specific Gamma Imaging (BSGI) for Breast Cancer: Usefulness of Dual-Phase Imaging with (99m)Tc-sestamibi

PURPOSE

The aim of this study was to investigate the usefulness of breast-specific gamma imaging (BSGI) with dual-phase imaging for increasing diagnostic performance and interpreter confidence.

METHODS

We studied 76 consecutive patients (mean age: 49.3 years, range: 33-61 years) who received 925 MBq (25 mCi) (99m)Tc-sestamibi intravenously. Craniocaudal and mediolateral oblique planar images were acquired for all patients. Delayed images were obtained from all patients 1 h after tracer injection, except for patients with no definite abnormal uptake. All images were classified into four categories: group 1 (definite negative) = no definite abnormal uptake; group 2 (possible negative) = symmetrically diffuse and amorphous uptake; group 3 (possible positive) = asymmetrically mild and nodular uptake; group 4 (definite positive) = asymmetrically intense and nodular uptake. To evaluate diagnostic performance, the BSGI studies were classified as positive (group 3 or 4) or negative (group 1 or 2) for malignancy according to a visual analysis. The final diagnoses were derived from histopathological confirmation and/or imaging follow-up after at least 6 months (range: 6-14 months) by both ultrasonography and mammography.

RESULTS

The patients' ages ranged from 33 to 61 years, with an average of 49.3 years. Thirteen patients were diagnosed with malignancy, and 63 patients were diagnosed as negative for malignancy. Using early images, 43 patients were classified as group 1, 12 as group 2, 10 as group 3 and 11 as group 4. Based on early images, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of BSGI were 77 %, 83 %, 48 %, 95 % and 82 %, respectively. Dual-phase BSGI had a sensitivity, specificity, PPV, NPV and accuracy of 69 %, 95 %, 75 %, 94 % and 91 %, respectively. The BSGI specificity was significantly higher with dual-phase imaging than with single-phase imaging (p = 0.0078), but the sensitivity did not differ significantly (p = 1.0). Based on dual-phase imaging, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of BSGI for the evaluation of US BI-RADS 4 lesions were 60 %, 86 %, 67 %, 83 % and 78 %, respectively.

CONCLUSION

Dual-phase imaging in BSGI showed good diagnostic performance and would be useful for increasing interpreter diagnostic confidence, with higher specificity, positive predictive value and accuracy for breast cancer screening as well as the differential diagnosis of breast disease compared with single-phase imaging.

Effectiveness of breast-specific gamma imaging (BSGI) for breast cancer in Korea: a comparative study

Despite the fact that mammography has been the golden standard in breast cancer detection for several decades, its sensitivity decreases for women with dense breast tissue, which happens to be common in Korea. As an alternative, breast ultrasonography can be effective diagnostic modalities that complement the defect of mammography. Recently, breast-specific gamma imaging (BSGI) has been introduced as a new diagnostic modality for breast cancer. This study was designed to analyze the effectiveness of BSGI in particular. In a retrospective study, 471 patients underwent BSGI, breast ultrasonography, and mammography simultaneously during the period between February 2009 and March 2010. The indications of BSGI were as follows: (a) patient who was diagnosed with malignancy prior to surgery, (b) patient who is under follow up after cancer surgery, (c) patient with lesions which cannot be evaluated by breast ultrasonography or mammography, (d) patient with multiple benign lesions, and (e) patient with suspicious lesion who refuses biopsy. Among these patients, 121 patients underwent biopsy, whereas others were followed up with imaging studies. We compared the BSGI results with those of mammography, breast ultrasonography, and pathology. The mean age of the patients was 49.63 ± 10.43 years. There were 107 patients with 110 malignant lesions and 364 patients with benign lesions. Total 474 lesions were evaluated. The sensitivities of BSGI, mammography, and breast ultrasonography were 94.45%, 93.64%, and 98.18%, respectively, whereas the specificities of BSGI, mammography, and breast ultrasonography were 90.93%, 90.66%, and 87.09%, respectively. The sensitivity and specificity of BSGI for axillary lymph node (LN) status were 44.7 4% and 87.88%, respectively. BSGI is a good complementary imaging modality with high sensitivity and high specificity for breast cancer detection. However, it has low efficacy for the evaluation for axillary LN status.