Occult breast cancer: scintimammography with high-resolution breast-specific gamma camera in women at high risk for breast cancer.
OBJECTIVE
To prospectively evaluate a high-resolution breast-specific gamma camera for depicting occult breast cancer in women at high risk for breast cancer but with normal mammographic and physical examination findings.


METHODS
Institutional Review Board approval and informed consent were obtained. The study was HIPAA compliant. Ninety-four high-risk women (age range, 36-78 years; mean, 55 years) with normal mammographic (Breast Imaging Reporting and Data System [BI-RADS] 1 or 2) and physical examination findings were evaluated with scintimammography. After injection with 25-30 mCi (925-1110 MBq) of technetium 99m sestamibi, patients were imaged with a high-resolution small-field-of-view breast-specific gamma camera in craniocaudal and mediolateral oblique projections. Scintimammograms were prospectively classified according to focal radiotracer uptake as normal (score of 1), with no focal or diffuse uptake; benign (score of 2), with minimal patchy uptake; probably benign (score of 3), with scattered patchy uptake; probably abnormal (score of 4), with mild focal radiotracer uptake; and abnormal (score of 5), with marked focal radiotracer uptake. Mammographic breast density was categorized according to BI-RADS criteria. Patients with normal scintimammograms (scores of 1, 2, or 3) were followed up for 1 year with an annual mammogram, physical examination, and repeat scintimammography. Patients with abnormal scintimammograms (scores of 4 or 5) underwent ultrasonography (US), and those with focal hypoechoic lesions underwent biopsy. If no lesion was found during US, patients were followed up with scintimammography. Specific pathologic findings were compared with scintimammographic findings.


RESULTS
Of 94 women, 78 (83%) had normal scintimammograms (score of 1, 2, or 3) at initial examination and 16 (17%) had abnormal scintimammograms (score of 4 or 5). Fourteen (88%) of the 16 patients had either benign findings at biopsy or no focal abnormality at US; in two (12%) patients, invasive carcinoma was diagnosed at US-guided biopsy (9 mm each at pathologic examination).


CONCLUSIONS
High-resolution breast-specific scintimammography can depict small (<1-cm), mammographically occult, nonpalpable lesions in women at increased risk for breast cancer not otherwise identified at mammography or physical examination.
Brem
Rachel F
RF
Department of Radiology, Breast Imaging and Intervention Center, George Washington University Medical Center, 2150 Pennsylvania Ave NW, Washington, DC 20037, USA. rbrem@mfa.fwu.edu
Rapelyea
Jocelyn A
JA
Zisman
Gilat
G
Mohtashemi
Kevin
K
Raub
Joyce
J
Teal
Christine B
CB
Majewski
Stan
S
Welch
Benjamin L
BL
D000328:Adult; D000368:Aged; D001706:Biopsy; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D015902:Gamma Cameras; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D011877:Radionuclide Imaging; D017256:Technetium Tc 99m Sestamibi; D014463:Ultrasonography
D017256:Technetium Tc 99m Sestamibi