Sensitivity and specificity of planar scintimammography with 99mTc-sestamibi

The development of breast radiology: the Acta Radiologica perspective

The encouraging results of modern breast cancer care builds on tremendous improvements in diagnostics and therapy during the 20th century. Scandinavian countries have made important footprints in the development of breast diagnostics regarding technical development of imaging, cell and tissue sampling methods and, not least, population screening with mammography. The multimodality approach in combination with multidisciplinary clinical work in breast cancer serve as a role model for the management of many cancer types worldwide. The development of breast radiology is well represented in the research published in this journal and this historical review will describe the most important steps.

Tc-99m sestamibi scintimammography for the diagnosis of breast cancer: meta-analysis and meta-regression

Tc-99m sestamibi (MIBI) is a relatively noninvasive diagnostic modality in the evaluation of breast cancer. The purpose of this study was to review the existing literature on the accuracy of Tc-99m MIBI in the diagnosis of breast cancer. After a systematic review of English-language studies, the sensitivity, specificity, and other measures of accuracy of Tc-99m MIBI in the diagnosis of breast cancer were pooled using random-effects models. Summary receiver operating characteristic curves were used to summarize the overall test performance. Forty-five studies met our inclusion criteria. The summary estimates for Tc-99m MIBI in the diagnosis of breast cancer in the studies included were as follows: sensitivity, 0.83 [95% confidence interval (CI), 0.82-0.84]; specificity, 0.85 (95% CI, 0.83-0.86); positive likelihood ratio, 5.06 (95% CI, 4.26-6.01); negative likelihood ratio, 0.20 (95% CI, 0.17-0.24); and diagnostic odds ratio, 27.63 (95% CI, 21.63-36.10). For patients with a palpable mass, the sensitivity and specificity were 87 and 86%, respectively. For patients without a palpable mass, the sensitivity and specificity were 59 and 89%, respectively. Tc-99m MIBI has a high level of overall accuracy for the diagnosis of breast cancer.

99MTechnetium-sestamibi scintimammography in non-palpable breast lesions found on screening X-ray mammography

OBJECTIVE

The sensitivity and specificity of (99m)Tc-sestamibi scintimammography in patients with non-palpable breast lesions diagnosed by screening mammography and the value of (99m)Tc-sestamibi to detect axillary lymph node metastases was determined.

METHODS

Between September 2000 and December 2003, 103 females with non-palpable breast lesions were included for further evaluation. X-ray mammography was repeated and 99mTc-sestamibi scintimammography performed within one-week. Anterior, and left and right lateral images were obtained. The scintimammography was analysed by 2 experienced observers who were blinded to the clinical, pathological, and radiological results. The sensitivity and specificity of scintimammography to diagnose non-palpable lesion(s), including the axillary regions, was compared with histopathology, clinical, and radiological follow up.

RESULTS

Two patients (one non-small lung cancer and one non-Hodgkin's disease) were excluded. Both showed (99m)Tc-sestamibi avid lesions in the breast and axillary region. In the remaining 101 patients, 37 true positive (TP), 4 false positive (FP), 52 true negative (TN), and 8 false negative (FN) breast carcinomas were found. The specificity was 92.8%, sensitivity 82.2%, positive predictive value (PPV) 90.2%, and negative predictive value (NPV) 86.6%. (99m)Tc-sestamibi scintimammography showed axillary lesions in 5/15 (33%) patients with axillary lymph node metastasis.

CONCLUSION

In patients with non-palpable lesions diagnosed by screening- X-ray-mammography, (99m)Tc-sestamibi scintimammography provided high specificity and PPV. Furthermore, (99m)Tc-sestamibi scintimammography detected 33% of patients with axillary lymph node metastases. Therefore, (99m)Tc-sestamibi scintimammography could be of incremental value in the surgical work-up of these patients.

A meta-analysis of scintimammography: an evidence-based approach to its clinical utility

BACKGROUND

Scintimammography using (99m)Tc-labelled isonitriles, sestamibi and tetrofosmin, has become a mature technique in the adjunctive setting for the diagnosis of primary breast cancer. To establish an evidence base for its use, clinically, a meta-analysis was performed on both single-site and multi-centre trials performed since January 1997.

METHODS

Using an on-line literature search all such trials containing 100 or more studies were identified. To prevent double counting of patients only the last published report from any centre was used.

RESULTS

A total of 2424 patients were identified in the single-site trial group, the smallest study having 105 patients and the largest 353 patients. The overall sensitivity was 85% and the specificity was 84%. In the multi-centre trial studies, published data from 3049 patients were included. The overall sensitivity in this group was also 85% and the specificity was 83%.

CONCLUSION

There is evidence that this is a robust imaging technique delivering high sensitivities and specificities in patients studied in both single-centre and multi-centre trials and, as such, can be relied on as an adjunctive method for the investigation of primary breast cancer.

Clinical applications of 99mTc-sestamibi scintimammography

Mammography is the imaging modality of choice in detection of early, nonpalpable breast cancer. However, scintimammography may prove to be a very useful adjunct to a nondiagnostic or difficult mammography. Future prospective studies will have to be designed so that the specific clinical applications of scintimammography will be well defined. To be clinically relevant, each niche where scintimammography is potentially indicated should be clearly evaluated and incorporated into an algorithm of investigation of breast cancer, taking into consideration the relative advantages and limitations of scintimammography. Special care to obtain high-quality scintimammographic studies is mandatory. Because poor quality studies may be the major drawback, the nuclear medicine community should remind the lesson learned from radiologic mammography. Furthermore, it is also hoped that significant improvement in the scintigraphic equipment and data acquisition will be seen in a very near future to have more widespread clinical diagnostic applications of scintimammography.

Comparison of quantitative and visual analysis of Tc-99m MIBI scintimammography for detection of primary breast cancer

Tc-99m MIBI scintimammography (SMM) is known to be a useful diagnostic tool for primary breast cancer. We conducted this study to compare the quantitative and visual analysis for detection of primary breast cancer and also investigated the incremental role of quantitative index of SMM.

METHODS

520 highly suspected breast cancer patients (malignant 370: palpable 232, nonpalpable 138; benign 150: palpable 67, nonpalpable 83) were included in this study. The SMM was performed 10 min after the injection of 750 MBq of Tc-99m MIBI. For visual analysis, three-scoring based method was used. The lesions to non-lesion ratios (L/Ns) were calculated. Receiver operating characteristic curve (ROC) analyses were performed to determine the optimal visual grade, to calculate cut-off value of L/N and to investigate whether the L/N could provide incremental value additive to visual analysis. The patients were divided into four groups according to the tumor size (group A: size </= 1cm; group B: 1cm < size </= 3 cm; group C: 3 cm < size </= 5 cm; group D: size > 5 cm). Also, the patients were divided into two groups according to age (under and over 45 years) to investigate incremental value of quantitative analysis.

RESULTS

When visual grade 3 was used as the cut-off grade, the sensitivity and specificity were 82.7 and 78%, respectively. The L/N of malignant breast disease was significantly higher than that of benign (2.00 +/- 1.88 versus 0.60 +/- 0.7, P < 0.01). When L/N of 1.27 was used as the cut-off value, the sensitivity and specificity of SMM were 77.6 and 83.3%, respectively. When the L/N was added to visual grade, the area under curve (AUC) of visual + quantitative (V + Q) analyses was higher than that of visual (V) and quantitative (Q) analyses (AUC 0.874 versus 0.803, P < 0.01). In group A and B, the AUCs of V + Q (0.861, 0.895) were higher than those of V (0.808, 0.781) and Q (0.808, 0.813). In group C, the AUC of V + Q (0.847) was higher than that of Q (0.803, P = 0.041). However, the AUC of V (0.915) was higher than that of V + Q (P = 0.009). In group D, there were no statistical differences between V + Q (0.685) and V (0.570, P = 0.058) and Q (0.620, P = 0.145). The V + Q revealed incremental value in the detection of primary breast cancer in both age groups. Also, in older age patients group (over 45 years), the specificities of Q and V + Q were higher than younger group (under 45 years). For axillary lymph node involvement, the sensitivity, specificity, and accuracy of SMM were 66.9, 70.1, and 68%, respectively.

CONCLUSION

From this study, the optimal visual grade for diagnosis of breast cancer was grade 3 and cut-off value of L/N was 1.27. Also, we found that the L/N provides incremental value additive to visual analysis. Especially, when the tumor is small (size </=3 cm), the L/N should be obtained for the diagnosis of breast cancer. The V + Q revealed incremental value in the detection of primary breast cancer in both age groups. Also, in older age patients group, the specificities of Q and V + Q were higher than younger group.

Incremental Diagnostic Value of Quantitative Analysis of Double Phase Tc-99m MIBI Scintimammography for the Detection of Primary Breast Cancer Additive to Visual Analysis

Tc-99m MIBI scintimammography (SMM) is known to be a useful diagnostic tool for primary breast cancer. We conducted this study to establish optimal visual grades for the detection of primary breast cancer and to investigate whether the quantitative indices of double phase SMM could provide incremental diagnostic value additive to visual analysis.

METHODS

Five hundred and twenty highly suspected breast cancer patients (malignant: 370; benign: 150) were included in this study. Double phase Tc-99m MIBI SMM (early: 10 min; delayed: 3 h) was performed after injection of 750 MBq of Tc-99m MIBI. For visual analysis, five scoring method was used. The early and delayed lesion to non-lesion ratios (L/N) and retention index (RI) were calculated. Receiver operating characteristic curve (ROC) analyses was performed to determine the optimal visual grade, to calculate cut-off value of quantitative indices for differentiation malignant and benign diseases and to investigate whether the quantitative indices could provide incremental diagnostic value additive to visual analysis. To investigate the incremental diagnostic value of quantitative index in variable tumor size groups, the patients were subdivided into four groups (group A: size <or= 1 cm, group B: 1 cm < size <or= 3 cm, group C: 3 cm < size <or= 5 cm, group D: size > 5 cm).

RESULTS

When over visual grade 3 was used as the cut-off grade for the diagnosis of breast cancer, the sensitivity and specificity were 75.5, 86.4%, respectively. Early L/N of malignant breast disease was significantly higher than that of benign (2.00 +/- 1.88 vs. 0.60 +/- 0.7; p < 0.01). However, delayed L/N and RI had no significant difference between malignant and benign breast diseases. When early L/N of 1.27 was used as the cut-off value, the sensitivity and specificity of SMM were 77.6, 83.3%, respectively. When the early L/N was added to visual grade, the area under curve (AUC) of visual + quantitative analysis (V + Q) was higher than that of visual analysis (V) alone (AUC 0.893 vs. 0.803; p < 0.01). In group A, the AUC of V + Q was higher than that of V alone (0.843 vs. 0.808; p = 0.029). In group B, the AUC of V + Q was also higher (0.913 vs. 0.781; p < 0.01). However, in groups C and D, the AUCs of V + Q and V were not different (0.926 vs. 0.915; p = 0.144: 0.663 vs. 0.570; p = 0.093). For axillary lymph node involvement, the sensitivity, specificity, and of SMM were 66.9, 70.1, and 68%, respectively.

CONCLUSION

From this study, the optimal visual interpretation grades for diagnosis of breast cancer were grades 4 and 5 and cut-off value of early L/N was 1.27. Also, we found that delayed image was not required for breast cancer detection and quantitative index of early L/N provide incremental diagnostic value additive to visual analysis. Especially, when the tumor is small (size <or= 3 cm), the early L/N should be obtained for the diagnosis of breast cancer.

Breast cancer diagnosis by scintimammography: a meta-analysis and review of the literature

Scintimammography is a relatively new, non-invasive diagnostic modality in the evaluation of breast cancer. The purpose of the current study was to review the existing literature on the accuracy of scintimammography in the diagnosis of breast cancer. A search of all articles published between 1st January 1967 and 31st December 1999 was conducted. A total of 64 unique studies were selected. Each scientific paper was reviewed for scientific merit by an epidemiologist, a surgeon and a surgical resident. Assessment of scientific merit was based on a scoring scheme developed for the study. The articles included in this review reported data on a total of 5340 patients assessed for breast cancer with scintimammography. The aggregated summary estimates on these patients were sensitivity: 85.2% and specificity: 86.6%. For patients with a palpable mass the sensitivity and specificity were 87.8 and 87.5%, respectively. For patients without a palpable mass the sensitivity was 66.8% and that for specificity was 86.9%. The results of this review have shown that scintimammography may be used effectively as an adjunct to mammography and physical examination in the diagnosis of breast cancer.

Complementary use of scintimammography with 99m-Tc-MIBI to triple diagnostic procedure in palpable and non-palpable breast lesions

PURPOSE

The aim of this study was to determine the clinical value of scintimammography with 99m-Tc-MIBI (Sc) as a complementary method to the triple diagnostic procedure in the diagnosis of breast lesions.

MATERIAL AND METHODS

Ninety-six consecutive patients with 65 palpable and 54 non-palpable breast lesions were included in a prospective study. All lesions were evaluated by clinical examination, mammography and fine-needle-aspiration cytology (FNAC), called triple diagnostic procedure (TD). Prone planar scintimammography with 99m-Tc-MIBI was performed in all patients. Five groups were defined for diagnosis: 1 = normal; 2 = benign; 3 = probably benign; 4 = highly suspect of malignancy; and 5 = malignant. In the calculations, groups 1-3 were considered benign, and 4-5 malignant. All lesions were excised and examined histologically. The additional value of Sc + TD procedure was studied separately for palpable and non-palpable lesions.

RESULTS

Histologically, 83 malignant and 36 benign lesions were found in the 119 breast lesions. Sensitivity for malignancy in palpable lesions of TD alone and of the combination TD + Sc were 95.6% and 100%, respectively. Sensitivity for malignancy in non-palpable lesions of TD and TD + Sc was 89.1% and 97.2%, respectively.

CONCLUSION

Adding scintimammography to the triple diagnostic procedure increased the sensitivity for the detection of both palpable and non-palpable breast cancers, but decreased the specificity.

99mTc-sestamibi uptake and histological malignancy grade in invasive breast carcinoma

The aim of this study was to investigate whether there is a correlation between (99m)Tc-sestamibi uptake and histological malignancy grade in breast carcinoma. Such a correlation could, prior to surgery and histopathological analysis, facilitate selection of patients who need adjuvant therapy. Ninety-six patients with mammographically determined lesions and/or a palpable tumour suspected for malignancy underwent (99m)Tc-sestamibi scintimammography prior to surgery. The final diagnosis was determined by histopathological examination. Benign lesions, cancer in situ and tumours located medially in the breast were excluded. Fifty-three invasive cancer lesions in 53 patients were finally included in the study. Planar scintigraphic breast imaging included two prone lateral projections and one anterior supine projection taken 10 min after injection of 700 MBq (99m)Tc-sestamibi. Focal (99m)Tc-sestamibi uptake in breast lesions was used as the scintigraphic criterion of abnormality. Tumour to background ratios were calculated with partial volume compensation, and histological malignancy grading was performed according to the Elston classification. A correlation was found between (99m)Tc-sestamibi uptake and histological malignancy grade in invasive breast carcinomas ( P<or=0.037).

Functional breast imaging using the single photon technique

Early diagnosis of carcinoma of the breast is currently attempted by mammography and physical examination which together have a sensitivity of 85%. Mammography has a positive predictive value of only 15 to 40 percent. The usefulness of scintimammography for the detection of carcinoma of the breast has been studied which demonstrated improved specificity compared to conventional mammography. In future, with the development or dedicated breast imager and new targeted radiopharmaceuticals, we can achieve detection of smaller than 1 cm carcinoma. This type of imaging enables us to detect cancer at its 'pre-anatomic' stage.

The role of Tc99m-sestamibi scintimammography in combination with the triple assessment of primary breast cancer

AIM

The aim of this study was to evaluate if Tc99m-sestamibi scintimammography in addition to the triple assessment consisting of clinical examination, mammography, breast ultrasonography and fine needle aspiration cytology (FNA) enhances the diagnosis of breast cancer and helps in avoiding unnecessary operative biopsies.

METHODS

Pre-operational scintimammography was performed within 2 weeks of operation to 46 consecutive patients with abnormal findings in clinical breast examination, mammography or ultrasonography. Three patients had abnormalities in both breasts. Histological diagnosis was obtained in all 49 cases.

RESULTS

The histological diagnosis was benign in 18 (37%) cases and malignant in 31 (63%) cases. The overall sensitivity of scintimammography was 77% and the specificity was 61%. The sensitivity of scintimammography was 95% in invasive ductal carcinoma, 50% in invasive lobular carcinoma and 25% in ductal carcinoma in situ. Scintimammography showed 100% sensitivity in cases with invasive carcinoma, with highly suspicious findings for malignancy in the other examinations. The sensitivity was 63% in cases with indeterminate or contradictory findings in mammography, ultrasonography and FNA.

CONCLUSIONS

Adding scintimammography to the triple assessment does not seem to be helpful in the diagnosis of breast abnormalities because of low sensitivity in malignant cases with a challenging diagnosis by mammography, ultrasonography and FNA, and because of low overall specificity.

Breast tumor localization using sestamibi

PURPOSE

The sensitivity of sestamibi scanning is 85% for breast lesions that measure >or=1 cm in diameter. This detection technique complements mammography and clinical examination and can benefit patients with very dense breast tissue. An innovation in nuclear imaging uses a lead marker for localization.

MATERIALS AND METHODS

A 53-year-old woman underwent scintigraphy to clarify the indeterminate findings of a mammogram. Left breast biopsies 7 and 8 years earlier had yielded benign results. Mammography revealed a somewhat asymmetric stromal pattern, but the tissue appeared stable compared with results of previous studies. No focal abnormalities were identified. The original sestamibi breast scan revealed focally increased sestamibi uptake in the left breast. She was referred for another sestamibi scan because no radiographic or palpable abnormality correlated with the scintigraphic findings, and the lesion was believed to be nonlocalizable. Histologic examination revealed high-grade, poorly differentiated infiltrating ductal adenocarcinoma.

RESULTS

After intravenous administration of Tc-99m sestamibi, the site of the lesion was identified using a lead marker, the persistence scope, and localization needles. This facilitated surgical removal.

CONCLUSION

Using a lead marker allows placement of localization wires to guide surgical breast biopsy in patients whose lesions are visible by scintigraphy but not via mammography or palpation.

Screening women at high risk of breast cancer on the basis of evidence

Geneticists are able to identify the risk of breast cancer. Strategies on offer include prevention, early diagnosis by screening, and prophylactic surgery. This paper analyses the evidence for offering screening. The radiation dose of mammography has been measured, but the risk is not fully known. Mammography screening of women of 40-50 years in the normal population has known effect. Little evidence is available for women under 40 years or for women with genetic susceptibility to breast cancer. Dense parenchymal pattern is associated with high grade cancers, and is both a risk factor and a reason for impaired screening sensitivity. Whether this applies to younger women or women at high risk is speculative. The pathological features of the cancers in gene carriers show differences from those occurring in normal women. This work should be correlated with imaging features. There is no literature to support the use of newer imaging methods in these women. Ultrasound and MRI avoid radiation and may be useful in dense breasts. SestaMIBI and PET scanning are not yet mature enough for screening, and may never have such a role. Any newer modality must be subjected to a formal randomised trial before being offered to screen women at high risk.

Development of a miniature scintillation camera using an NaI(Tl) scintillator and PSPMT for scintimammography

We have developed a small scintillation camera dedicated to breast imaging and have evaluated the performance of the system. In order to increase the limited field of view (FOV) determined by the size of a position-sensitive photomultiplier tube (PSPMT), the imaging characteristics of a diverging hole collimator (DHC) were also investigated. The small scintillation camera system consists of an NaI(Tl) crystal (60 mm x 60 mm x 6 mm) coupled to a Hamamatsu R3941 PSPMT, a resistor chain circuit, preamplifiers, nuclear instrument modules, an analogue to digital converter and a PC for control and display. The intrinsic energy resolution of the system was 12.9% FWHM at 140 keV. The spatial resolution was measured using a line-slit mask and 99mTc point sources and was 3.1 mm FWHM. The intrinsic sensitivity of the system was approximately 162 counts/s kBq(-1). The DHC made it possible to image a larger FOV (75 x 75 mm2 at the surface of collimator) than a parallel-hole collimator (60 x 60 mm2). The system sensitivity obtained using the DHC gradually decreased with distance (3% at 1 cm, 6% at 2 cm and 9% at 3 cm). The results demonstrate that the system developed in this study could be utilized clinically to image malignant breast tumours. A DHC can be employed to expand the FOV of the system confined by the size of PSPMT with a modest compromise in the performance of the system.