Imaging in situ breast carcinoma (with or without an invasive component) with technetium-99m pentavalent dimercaptosuccinic acid and technetium-99m 2-methoxy isobutyl isonitrile scintimammography

Abstract

Introduction: The aim of the study was to retrospectively define specific features of the technetium-99m pentavalent dimercaptosuccinic acid (99mTc-(V)DMSA) and technetium-99m 2-methoxy isobutyl isonitrile (99mTc-Sestamibi [99mTc-MIBI]) distribution in ductal breast carcinoma in situ and lobular breast carcinoma in situ (DCIS/LCIS), in relation to mammographic, histological and immunohistochemical parameters.

Materials and methods: One hundred and two patients with suspicious palpation or mammographic findings were submitted preoperatively to scintimammography (a total of 72 patients with 99mTc-(V)DMSA and a total of 75 patients with 99mTc-Sestamibi, 45 patients receiving both radiotracers). Images were acquired at 10 min and 60 min, and were evaluated for a pattern of diffuse radiotracer accumulation. The tumor-to-background ratios were correlated (T-pair test) with mammographic, histological and immunohistochemical characteristics.

Results: Histology confirmed malignancy in 46/102 patients: 20/46 patients had DCIS/LCIS, with or without coexistent invasive lesions, and 26/46 patients had isolated invasive carcinomas. Diffuse 99mTc-(V)DMSA accumulation was noticed in 18/19 cases and 99mTc-Sestamibi in 6/13 DCIS/LCIS cases. Epithelial hyperplasia demonstrated a similar accumulation pattern. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value for each tracer were calculated. Solely for 99mTc-(V)DMSA, the tumor-to-background ratio was significantly higher at 60 min than at 10 min and the diffuse uptake was significantly associated with suspicious microcalcifications, with the cell proliferation index > or = 40% and with c-erbB-2 > or = 10%.

Conclusion: 99mTc-(V)DMSA showed high sensitivity and 99mTc-Sestamibi showed high specificity in detecting in situ breast carcinoma (99mTc-(V)DMSA especially in cases with increased cell proliferation), and these radiotracers could provide clinicians with preoperative information not always obtainable by mammography.

Figure 1

A 3-cm infiltrating ductal carcinoma of the right breast. Scintimammography, right lateral projection: ^99mTc-(V)DMSA at 10 min and 60 min (upper row, i-ii); ^99mTc-Sestamibi (^99mTc-MIBI) at 13 min and 55 min (bottom row, iii-iv). Focal radiotracer accumulation (arrowhead) in the upper breast hemisphere, corresponding to the invasive tumor, visible in early and late images with both radiotracers. There is no diffuse uptake pattern in the breast; the studies are considered negative for in situ carcinoma.

Figure 2

A 5-cm infiltrating ductal carcinoma, grade 2, with 9-cm, comedo-type, ductal carcinoma in situ of the right breast (patient 4). (a) Mammography, medio-lateral projection. Nodule with spiky margins (transparent arrow), close to the chest wall in the upper breast hemisphere. (b) Scintimammography, right lateral projection: ^99mTc-Sestamibi (^99mTc-MIBI) at 5 min and 60 min (upper row, i-ii); ^99mTc-(V)DMSA at 10 min and 60 min (bottom row, iii-iv). Spindle-shaped focal accumulation (arrowhead) in the area corresponding to the radiological abnormality. The 60-min ^99mTc-(V)DMSA image additionally reveals an extensive area of diffuse heterogeneous patchy tracer uptake (arrow) extending below and anterior to the margins of the focal accumulation. Lymph node involvement in the axilla is visible (curved arrow).

Figure 3

A 6-cm infiltrating ductal carcinoma, grade 2, with coexistent 5-cm ductal carcinoma in situ, comedo type, of the left breast (patient 1). (a) Mammography, medio-lateral projection. Multinodular opacity with abnormal radiating spicules and clustered microcalcifications (transparent arrow) behind the nipple. (b) Scintimammography, left lateral projection: ^99mTc-Sestamibi (^99mTc-MIBI) at 10 min and 65 min (upper row, i-ii); ^99mTc-(V)DMSA at 15 min and 60 min (bottom row, iii-iv). Increased bifocal ^99mTc-Sestamibi uptake (arrowheads) behind the nipple, clearly defining the invasive component of the tumor. Focal ^99mTc-(V)DMSA accumulation in the same area (arrowhead), with additional diffuse uptake (arrow) extending inferiorly, more prominent at 60 min and corresponding to the in situ tumor component. No diffuse pattern is imaged with ^99mTc-Sestamibi. (c) Scintimammography, left lateral projection: ^99mTc-(V)DMSA at 60 min (same as (b) iv), with regions of interest (ROIs) drawn. ROI selection for diffuse uptake with each tracer is based on the comparison between early and late images (see text).

Figure 4

A 4.5-cm ductal carcinoma in situ of the left breast, comedo, solid and cribriform type (patient 18). (a) Mammography, medio-lateral projection. Microcalcifications (transparent arrow) behind the nipple. (b) Scintimammography, left lateral projection: ^99mTc-(V)DMSA at 10 min and 60 min (i-ii). Diffuse semi-lunar accumulation (arrow) extending behind the nipple, more prominent in the late image. ^99mTc-Sestamibi scan was not performed in this patient.

Figure 5

A 4-cm infiltrating lobular carcinoma, grade 3, associated with 6-cm lobular carcinoma in situ (LCIS) of the left breast in a 65-year-old woman (patient 20). (a) Mammography, cranio-caudal projection. Nodular opacity (asterisk) in the inner hemisphere of the breast. (b) Scintimammography, left lateral projection: ^99mTc-Sestamibi (^99mTc-MIBI) at 10 min and 60 min (upper row, i-ii); ^99mTc-(V)DMSA at 10 min and 60 min (bottom row, iii-iv). Focal increased uptake (arrowhead) between upper and lower breast hemisphere, imaged by both radiotracers, corresponding to an invasive tumor. A diffuse patchy 'V'-shaped tracer accumulation (arrows), surrounding the focal activity and extending anterior to it, is revealed with ^99mTc-(V)DMSA at 60 min only (iv). It corresponds to LCIS.

Figure 6

Atypical epithelial hyperplasia of the right breast in a 41-year-old woman. Scintimammography, right lateral projection: ^99mTc-(V)DMSA at 15 min and 75 min (upper row, i-ii); ^99mTc-Sestamibi (^99mTc-MIBI) at 10 min and 70 min (bottom row, iii-iv). Increased diffuse homogeneous ^99mTc-(V)DMSA uptake (arrow) at early and late acquisitions, more prominent in the late image. Very faint (hardly visible) ^99mTc-Sestamibi activity (arrow) in the same area.

Figure 7

Ductal carcinoma in situ (DCIS), comedo, solid and cribriform type (patient 18). (a) Tumor section (hematoxylin & eosin, × 25). Regions of DCIS (arrowheads), within normal breast tissue (asterisk). (b) In vitro ^99mTc-(V)DMSA autoradiogram of the same section (× 25). Distribution of the radioactivity in the same tumor section. The sites of intense tracer uptake (curved arrow) appear darker. (c) Overlay of stained tumor section and autoradiogram. The histologically detected lesion is well correlated with the tissue sites of intense ^99mTc-(V)DMSA uptake.