The role of technetium-99m methoxyisobutyl isonitrile scintigraphy in suspected recurrent breast cancer

Scintimammography in conjunction with ultrasonography for local breast cancer recurrence in post-mastectomy breast

The aim of this study was to compare the usefulness of (99)Tc(m)-methoxy-isobutyl-isonitrile (MIBI) scintimammography and ultrasonography, alone and in combination, for the detection of chest wall recurrence in the post-mastectomy breast. A total of 41 consecutive post-mastectomy patients (mean age 46.6 years; median age 45 years) with clinical suspicion of breast cancer recurrence were evaluated. For scintimammography all patients received a 740-900 MBq iv injection of (99)Tc(m)-MIBI; planar images were taken 5-10 min post-injection followed by supine single photon emission CT. Breast ultrasonography was performed in each patient using a 7.5 MHz transducer. Both MIBI uptake and ultrasound findings were documented using standard protocols. All patients had fine needle aspiration cytology biopsy (FNAC), core biopsy or excision biopsy for final tissue diagnosis. Of the 41 patients, 24 had true positive signs of local breast cancer recurrence upon ultrasonography, 10 were diagnosed as true negatives, a sensitivity of 86%, specificity 77%, positive predictive value (PPV) 89%, negative predictive value (NPV) 71% and accuracy 83% (p = 0.001). By comparison, scintimammography findings were found to be true positive in 25 patients and true negative in 12 patients - sensitivity 89%, specificity 92%, PPV 96%, NPV 80% and accuracy 90% (p = 0.001). Using a combination of these two modalities, the combined sensitivity was 100%, specificity 77%, PPV 90%, NPV 100% and accuracy 93%. The high NPV of the two studies in combination implies a potential use of this approach to exclude recurrent disease in patients with a low initial index of suspicion and/or when histology is indeterminate.

Chest wall recurrence of breast cancer demonstrated on 99mTc-MIBI scintimammography

BACKGROUND

The mastectomy site is usually assessed by clinical examination and ultrasonography for recurrence of breast cancer, although post-surgical and radiotherapy changes limit the accuracy of these methods. MRI has been used successfully but it remains an expensive modality and may not be readily available. Scintimammography is an alternative method which has the advantage of not being affected by post-operative morphological changes.

AIM

To evaluate the usefulness of planar Tc-MIBI scintimammography and supine Tc-MIBI SPECT in the detection of chest wall recurrence post-mastectomy.

METHODS

The study population comprised of 26 patients (mean age, 47.15 years; median age 47 years; age range, 22-77 years) with suspected chest wall recurrence of breast cancer on clinical examination. All patients received a 740-1000 MBq bolus i.v. injection of Tc-MIBI preferably in the pedal vein. At 5-10 min post-injection planar images were obtained in the prone lateral and supine anterior positions using a double-head gamma camera. After planar imaging supine SPECT was performed (64 projections, 64x64 matrix, 30 s.frame). MIBI uptake was scored as follows: 1 = normal uptake (compared with contralateral side); 2 = focal low uptake (equivocal); and 3 = focal high uptake (positive). All patients underwent excision biopsy or FNAC for tissue diagnosis. FNAC was considered sufficient if unequivocally positive.

RESULTS

For the 26 patients, planar scintimammography was found true positive in 14 and true negative in seven. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 78%, 87.5%, 93%, 64% and 81%, respectively (P<0.001). SPECT showed a significantly higher overall sensitivity than planar imaging (89% vs. 78%; P<0.001). SPECT and planar imaging showed the same specificity (87.5%). SPECT showed a significantly higher negative predictive value and accuracy than planar imaging (78% vs. 64% and 88% vs. 81%, respectively; P<0.05).

CONCLUSION

Scintimammography is a reliable diagnostic tool and appears accurate in the detection of chest wall recurrence. SPECT shows high positive predictive value and aids in the diagnosis of the chest wall recurrence with greater confidence.

99m Tc-sestamibi scintimammography in detection of recurrent breast cancer

The aim of this study was to asses the accuracy of 99mTc-sestamibi scintimammography in patients with suspected recurrent breast cancer in the breast or loco regional tissues. After routine analyses in twenty-eight women (clinical examination, ultrasound, X-ray mammography, and fine needle aspiration biopsy) they were examined by scintimammography. All patients with suspected recurrent cancer in the breast or loco regional tissues (19) undergone surgery and the final diagnosis was determined by histopathological examination. Another 9 patients were followed 6-24 months. The scintigraphic studies were correlated with radiological findings and/or with histopathology. There were 19 patients with recurrent tumours (15 with loco-regional recurrent and 4 in another breast). X-ray mammography identified 13 of these cancers. 99mTc-sestamibi scintimammography identified seventeen of recurrent breast cancers. In the seven out of nine patients without cancer, scintimammography were reported as having no changes consistent with cancer. X-ray mammography showed suspected cancer lesions in four out of nine patients without cancer. There were two false-positive scintimammograms and one false negative. Axillary lymph node recurrence occurred in four patients. All of them were positive on scintimammography. 99mTc-sestamibi scintimammography showed higher sensitivity, specificity and accuracy per patient than did X-ray mammography (90,9% vs. 63,6%, 71,4% vs. 57,1% and 83,3% vs. 61,1%, respectively). To identifying recurrent breast cancer disease is better to use scintimammography than X-ray mammography.

Monitoring therapy in breast cancer

Breast cancer remains one of the most common cancers in the developed world. New treatments are proving effective against both limited disease and metastases. Nuclear medicine is in a unique position as it is one of the only methods used to image the breast which is linked to cell cycle changes, the receptors on the cell surface and the cells' response to chemotherapy. Nuclear medicine is unaffected by the anatomical changes seen post-chemotherapy and radiotherapy and is uniquely placed to become a major methodology in the continued assessment of the breast cancer patient. However, before this can happen the utility of nuclear medicine techniques must be proved in multi-centre trials.