The diagnostic value of planar and SPET scintimammography in different age groups

[Molecular breast imaging. An update]

CLINICAL/METHODICAL ISSUE

The aim of molecular imaging is to visualize and quantify biological, physiological and pathological processes at cellular and molecular levels. Molecular imaging using various techniques has recently become established in breast imaging.

STANDARD RADIOLOGICAL METHODS

Currently molecular imaging techniques comprise multiparametric magnetic resonance imaging (MRI) using dynamic contrast-enhanced MRI (DCE-MRI), diffusion-weighted imaging (DWI), proton MR spectroscopy ((1)H-MRSI), nuclear imaging by breast-specific gamma imaging (BSGI), positron emission tomography (PET) and positron emission mammography (PEM) and combinations of techniques (e.g. PET-CT and multiparametric PET-MRI).

METHODICAL INNOVATIONS

Recently, novel techniques for molecular imaging of breast tumors, such as sodium imaging ((23)Na-MRI), phosphorus spectroscopy ((31)P-MRSI) and hyperpolarized MRI as well as specific radiotracers have been developed and are currently under investigation.

PRACTICAL RECOMMENDATIONS

It can be expected that molecular imaging of breast tumors will enable a simultaneous assessment of the multiple metabolic and molecular processes involved in cancer development and thus an improved detection, characterization, staging and monitoring of response to treatment will become possible.

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.

Molecular Imaging in Breast Cancer - Potential Future Aspects

SUMMARY: Molecular imaging aims to visualize and quantify biological, physiological, and pathological processes at cellular and molecular levels. Recently, molecular imaging has been introduced into breast cancer imaging. In this review, we will present a survey of the molecular imaging techniques that are either clinically available or are being introduced into clinical imaging. We will discuss nuclear imaging and multiparametric magnetic resonance imaging as well as the combined application of molecular imaging in the assessment of breast lesions. In addition, we will briefly discuss other evolving molecular imaging techniques, such as phosphorus magnetic resonance spectroscopic imaging and sodium imaging.

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.

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.

Nuclear medicine and breast cancer: a review of current strategies and novel therapies

While breast cancer is still increasing in frequency, new diagnostic procedures are now available to challenge existing procedures and to make diagnosis of breast cancer more accurate and reliable. Mammography remains the standard investigation to reveal disease in an asymptomatic population: it can also be used to diagnose breast cancer in symptomatic patients (e.g. those with palpable breast lumps) and for guiding fine needle aspiration (FNA). Because the majority of breast lumps are benign, the challenge is to distinguish benign from malignant lesions without the use of invasive methods and this has attracted nuclear medicine physicians and medical oncologists to investigate the role of scintigraphic procedures to identify which patients require FNA. This review attempts to shed light on the various scintigraphic methods available which are of potential practical use in the assessment of malignant breast disease as well as looking at the possible role of nuclear medicine in the treatment of advanced disease.

Technetium-99m-Sestamibi Scintimammography to Detect Breast Cancer in Patients with Paraffinomas or Siliconomas After Breast Augmentation

As the mechanism of (99)mTc-MIBI scintimammography is different from that of anatomic modalities, the detection of breast cancer should not be affected by prior breast augmentation. The aim of this study was to compare the diagnostic accuracy of (99)mTc-MIBI scintimammography for breast cancer in patients with or without paraffinomas or siliconomas. Twenty-eight women with a history of paraffin or silicone injection into the breasts and 17 without were included. All patients received intravenous injection of 1110 MBq (99)mTc-MIBI and were subsequently examined using high-resolution planar and SPECT imaging 5 minutes after the injection. In the 45 patients with 87 breasts, 21 abnormal breasts were found at scintigraphy. The sensitivity, specificity, and accuracy to detect cancer in these breasts with paraffinomas or siliconomas were 100% (5/5), 92% (46/50), and 93% (51/55), respectively. For the breasts without paraffinomas or siliconomas, the sensitivity, specificity, and accuracy were 92% (11/12), 95% (19/20), and 94% (30/32), respectively, not significantly different (p = 0.51, 0.66, and 0.86, respectively). (99)mTc-MIBI scintimammography is both sensitive and specific for the detection of breast cancer, whether or not paraffinomas or siliconomas are present. The accuracy of scintimammography did not seem to be affected by prior breast augmentation.

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.

A review of the cost-effectiveness of Tc-99m sestamibi scintimammography in diagnosis of breast cancer in Taiwanese women with indeterminate mammographically dense breast

In general, biopsy is the preferred management method for women with indeterminate mammographically dense breasts. In this review, we describe a decision analysis model comparing technetium-99m methoxyisobutylisonitrile (Tc-99m sestamibi) scintimammography and excisional biopsy as breast cancer evaluation strategies for hypothetical cohorts of estimated 16,000-40,000 women with indeterminate mammographic probability of malignancy because of mammographically dense breasts. In cost-effectiveness analysis, quantitative decision tree sensitivity analysis was used to compare the conventional excision biopsy alone strategy (strategy A) with decision strategy for screening with Tc-99m sestamibi scintimammography before excision biopsy (strategy B) after an indeterminate mammogram. Strategy B showed a cost saving of US dollars 649,600-1,624,000 in reducing the cost of unnecessary biopsies. The total cost of strategy B showed a cost saving of US dollars 123,075-307,776 compared to strategy A. The analysis data indicate that Tc-99m sestamibi scintimammography can save the cost of unnecessary biopsies in Taiwanese women with non-diagnostic mammogram because of mammographically dense breasts.

Nuclear medicine in primary breast cancer imaging

The application of nuclear medicine techniques to study patients with breast cancer has recently raised its profile, particularly in the investigation 'indeterminate mammographic lesions'. This review briefly points out some of the difficulties encountered with other more conventional imaging modalities and describes the radionuclide techniques most frequently employed in the investigation of those patients with breast cancer. Both planar and single photon emission tomography methods are discussed including the use of monoclonal antibodies, perfusion ligands, receptor binding hormones and other specific radiotracers, non-specific tumour markers, as well as deoxyglucose and other amino acids labelled with positron emitting radionuclides.

Scintimammography: better detection of small-sized lesions with tomoscintigraphic than planar images, a phantom study

Planar (99)Tc(m)-methoxyisobutylisonitrile ((99)Tc(m)-MIBI) scintimammography has been used for several years to detect breast cancer tumours, but with low sensitivity for small lesions. Results of tomoscintimammography studies have not been conclusive. We conducted a phantom study to compare the detection of small-sized tumours with planar versus tomoscintigraphic images. We used a data spectrum anthropomorphic fillable breast phantom with two 9.8 mm and 12.4 mm spheres superficially or deep in the breast compartment with sphere/breast activity ratios varying from 3 to 6. We acquired planar and 180 degrees tomoscintigraphic images in each configuration using a double head standard gamma camera. In certain cases we varied different parameters (64x64 matrix or 360 degrees rotation) in a second series of tomoscintigraphic acquisitions. We simultaneously used filtered back-projection reconstruction (FBP) and iterative reconstruction (IR). Planar images were shown by the sphere in 10 out of 25 cases. Tomoscintigraphic images were shown by the sphere in nine out of 25 cases with FBP and in 18 out of 25 with IR. There was a significant difference between IR and FBP (P<0.01) and between planar and IR images (P<0.01), but no significant difference between planar and IR images. The noise/signal ratio was lower with planar images than with the two types of reconstruction (P<0.05) but was not significantly different between the two types of reconstruction. Contrast was lower on planar images than on the two types of reconstruction (P<0.05) and was also better on IR than on FBP images (P<0.05). Granularity was lower for planar images than for reconstruction images (P<0.01) and also lower for IR than for FBP (P<0.01). The tomoscintigraphic reconstructions acquired with a 64x64 matrix were only positive in four out of 10 cases, while they were positive in nine out of 10 with a 128x128 matrix. We concluded that, in this phantom study, tomoscintimammography with IR provides a significant improvement in the detection of small-sized breast tumours compared with planar images. In addition, for tomoscintigraphic images, a 128x128 matrix is preferable to a 64x64 matrix. Those results have, of course, to be confirmed in vivo in a large population of patients with small-sized breast lesions.

Tc-99m-MIBI scintimammography; SPECT versus planar imaging

This study compares single photon emission tomography (SPECT) with planar scintimammography. 16 normal, 54 benign and 80 malignant lesions were studied (total 150). 700 MBq of Tc99m-sestamibi (MIBI) was injected intravenously. Anterior supine, right and left lateral planar images were acquired in prone position at 2 hours post injection. After this a SPECT study (64 projections, 64 x 64 matrix, 30 sec/frame, anterior 180 degrees arc) was acquired in supine position. Attenuation coefficient of 0.12 and Butterworth order 5 Nyquist 0.9 filter was applied for reconstruction. A scoring system for visualization of lesions was devised with scores of 0 or 1 as negative and 2 or 3 as positive for MIBI uptake. Scores for each group of patients were added together and then compared between planar and SPECT studies.

RESULTS

Planar imaging missed 10 malignant lesions while SPECT missed only 4. Ten benign lesions showed uptake of MIBI on planar imaging while 11 showed uptake on SPECT. Cumulative scores for normal and benign groups did not show any significant difference between planar and SPECT imaging. The malignant group showed significant increase in score for SPECT. Specificity, false negative fraction and positive predictive value for planar imaging were 85.7%, 14.3% and 87.5%. These values did not show any significant difference for SPECT (84.5%, 15.5% and 87.4% respectively). Sensitivity, false negative fraction and negative predictive value for planar imaging (87.5%, 12.5% and 85.7%) was significantly different (p < 0.005) than SPECT (95%, 5% and 93.7% respectively). MIBI SPECT scintimammography improves the sensitivity, false negative fraction and negative predictive value of the planar imaging. In the absence of MIBI uptake on SPECT imaging, malignancy can be ruled out with great confidence, while only uptake should be further evaluated.

The role of 99mTc-sestamibi and other conventional radiopharmaceuticals in breast cancer diagnosis

The wide availability and the extensive use of screening mammography have resulted in an earlier diagnosis of breast cancer and in a significant reduction in the relative risk of dying from this disease. Despite technical improvements and major advantages associated with the use of mammography (and breast ultrasound), this procedure has some limitations in clinical practice, especially in women with dense breast tissue, implants, severe dysplastic disease, or significant architectural distortion following breast surgery or radiation therapy. Different noninvasive imaging techniques have been evaluated to overcome these limitations. Nuclear medicine also has been actively involved in the detection of breast cancer, using various types of radiopharmaceuticals. Currently, there are three radiotracers commonly used for breast imaging or scintimammography in either clinical practice or research: 99mTc-sestamibi and 99mTc-tetrofosmin (two agents used for myocardial perfusion imaging) and 99mTc-MDP (methylene diphosphonate, used for bone scintigraphy). 99mTc-sestamibi was the first radiopharmaceutical to be approved by the FDA for scintimammography. Several prospective studies have shown that the overall sensitivity of 99mTc-sestamibi scintimammography in detection of breast cancer was 85%, the specificity was 89%, and the positive and negative predictive values were 89% and 84% respectively. Similar numbers have been demonstrated for 99mTc-tetrofosmin and 99mTc-MDP scintimammography. Although not indicated as a screening procedure for the detection of breast cancer, scintimammography may play a useful and significant role in various specific clinical indications such as nondiagnostic or difficult mammography, and evaluation of high-risk patients, tumor response to chemotherapy, and axillary lymph node metastatic involvement.