Benign versus malignant breast disease: comparison of contrast-enhanced MR imaging and Tc-99m tetrofosmin scintimammography

Breast-specific gamma imaging as an adjunct modality for the diagnosis of invasive breast cancer with correlation to tumour size and grade

OBJECTIVES

The purpose of this study was to determine the sensitivity of breast-specific gamma imaging (BSGI) in the detection of invasive breast cancers and to characterise the sensitivity of BSGI based on tumour size and pathological grade.

METHODS

139 females with invasive carcinoma who underwent BSGI were retrospectively reviewed. Patients were injected in the antecubital vein with 20-30 mCi (925-1110 MBq) of (99m)Tc-sestamibi. Images were obtained with a high-resolution, breast-specific gamma camera (Dilon 6800; Dilon Technologies, Newport News, VA) and were categorised based on radiotracer uptake as normal, normal with heterogeneous uptake, probably abnormal and abnormal. For a positive examination, the region of the area of increased uptake had to correlate with the laterality and location of the biopsy-proven cancer.

RESULTS

149 invasive cancers in 139 patients with a mean size of 1.8 cm (0.2-8.5 cm) were included. 146 were identified with BSGI (98.0%). All cancers which measured ≥ 0.7 cm (n = 123) as well as all cancers grade 2 or higher (n = 102), regardless of tumour size, were identified with BSGI (100%). There were 6 cancers that were pathological grade 1 and measured <7 mm, of which 50% (3/6) were identified with BSGI. The overall sensitivity of BSGI for the detection of invasive breast cancer is 98.0%. The sensitivity for subcentimetre cancers is 88.5% (23/26).

CONCLUSION

BSGI has a high sensitivity for the detection of invasive breast cancer. Our results demonstrate that BSGI detected all invasive breast cancers pathological grade 2 and higher regardless of size and all cancers which measured ≥ 7 mm regardless of grade. BSGI can reliably detect invasive breast cancers and is a useful adjunct imaging modality for the diagnosis of breast cancer.

Alternative Breast-Imaging Approaches

Although conventional breast-imaging techniques routinely include mammography and ultrasound, growing interest in other approaches, perhaps most notably MR imaging, has drawn increasing attention to exploiting the anatomic and physiologic basis for understanding breast cancer. Nuclear medicine techniques have been applied in several circumstances with the intent of approaching or defining a role for molecular imaging, exemplified by the use of F-18 fluorodeoxyglucose and positron emission tomography. Other techniques, including exploitation of additional components of the electromagnetic spectrum, have provided novel concepts that may ripen into clinical use.

Detecting infiltrating lobular carcinoma using scintimammographic breast specific gamma imaging

This study evaluated the effectiveness of scintimammography performed with gamma cameras optimized for breast imaging in the detection of infiltrating lobular carcinoma. This new procedure, Breast Specific Gamma Imaging (BSGI), was conducted on 105 patient presenting with 113 breast lesions. Studies were conducted at two medical centers using three prototype cameras [14, 16]. Biopsy and pathology reports were obtained for all cases and, of the 34 detected carcinomas, 6 were determined to be infiltrating lobular type without mixed component other than lobular carcinoma in situ. Of the 6 lesions, 4 were smaller than 1 cm, the smallest moasuring 3 mm at biopsy. BSGI detected all 6 of the lobular carcinomas and correctly identified the secondary lesion in the only multifocal case. The BSGI foci sizes matched the lesion size at biopsy to within +/-5.5 mm, with about an equal number of cases ovar and under estimated.

CONCLUSION

BSGI provides an effective tool for the detection of lobular carcinoma and in the determination of lesion size and multifocality.

Complementary role of adjunctive breast magnetic resonance imaging and scintimammography in patients of all ages undergoing breast cancer surgery

The aims of this study were to assess breast MRI and scintimammography (SMM) for the detection of breast cancer, and to determine any complementary role of these tests to each other and conventional imaging. Seventy-two patients (age 35-81 years) with a suspicious breast mass were investigated by mammography, breast ultrasound, breast MRI and SMM before undergoing surgical excision of the breast mass. Sensitivity, specificity and area under receiver operator characteristic curves were calculated for each test. Of the 72 patients, there were 66 proven malignant tumours, including two patients with bilateral breast cancer. When comparing the diagnostic sensitivity of breast MRI and SMM for lesion size, both tests showed higher sensitivities for lesions >25 mm in size, particularly for SMM. When these tests were compared for patient age, patients less than 51 years showed higher sensitivities for both tests. This was statistically significant for breast MRI. The overall respective diagnostic sensitivities for mammography, mammography with breast ultrasound, breast MRI and SMM were 56, 67, 86 and 85%. The differences were significant between mammography, mammography/ultrasound and both breast MRI and SMM. Breast MRI and SMM offer incremental diagnostic advantage in the diagnosis of breast cancer. Although improved diagnostic accuracy is seen in patients of all ages, those patients less than 51 years of age receive the greatest diagnostic benefit.

Noncardiac findings on dual-isotope myocardial perfusion SPECT

BACKGROUND

This study examined the frequency of reporting noncardiac findings (NCFs), such as malignancies from inspection of raw projection images with dual-isotope single photon emission computed tomography (SPECT) perfusion imaging, which could potentially be of greater clinical importance than myocardial perfusion imaging alone. Dual-isotope (ie, rest thallium 201 and stress technetium 99m sestamibi [MIBI] or Tc-99m tetrofosmin [TET]) SPECT myocardial perfusion imaging combines multipotential tracers for noncardiac purposes (Tl-201 for renal or splenic imaging, inflammation, or lymphoma and MIBI or TET for hepatobiliary imaging and detecting increased mitochondrial number or activity in neoplastic processes). These images are optimally interpreted with cinematic inspection of the raw projection data, but this may not be practiced uniformly in every laboratory.

METHODS AND RESULTS

We reviewed 12,526 computer-generated text reports of dual-isotope perfusion SPECT studies from a 6-year period for NCFs. NCFs were categorized by organ and by probability of malignancy: high (eg, focal breast or lung uptake of MIBI or TET), intermediate (eg, lymph node uptake or thyroid abnormalities), or low (eg, filling defects in liver, kidney, spleen, or gall bladder; ascites; or pleural effusions). Confirmatory imaging studies or clinical confirmation for each NCF was sought. There were a total of 207 NCFs identified in 180 reports (1.7% of reports, ranging from 0% to 2.8% of reports of individual interpreters). Of these, 107 NCFs were unsuspected before SPECT; 24% were considered at high probability for malignancy, and 24% were considered intermediate in likelihood of malignancy. Follow-up data were available for 178 NCFs, confirming 88% of these findings, including 82% of breast foci, 62% of lung foci, 86% of hepatobiliary/spleen abnormalities, and 94% of renal abnormalities. The probability of malignancy was highest (82%) in breast or lung foci in which uptake of both Tl-201 and the Tc-99m-labeled agent was present.

CONCLUSIONS

In patients referred for evaluation of myocardial perfusion, NCFs are unusual and require systematic and careful inspection of projection images for their detection. With Tl-201, TET, MIBI, or dual-isotope imaging, detecting and reporting NCFs may occasionally result in life-saving early cancer identification.

Predicting multidrug resistance-related protein and P-glycoprotein expression with technetium-99 m tetrofosmin mammoscintigraphy

The purpose of this study was a retrospective survey of 40 patients with infiltrating ductal breast carcinoma to evaluate the relationships between the degree of accumulation of technetium-99m tetrofosmin (Tc-TF), multidrug resistance-related protein (MRP) expression and P-glycoprotein (Pgp) expression in breast cancer tissue. Immunohistochemical analysis (IHA) was performed on pathological specimens of the 40 breast cancers to determine Pgp and MRP expression. The results of IHA, were used as the basis for dividing the 40 breast cancers into four groups: A, 10 tumors with positive MRP and Pgp expressions; B, 10 tumors with positive MRP but negative Pgp expression; C, 10 tumors with negative MRP but positive Pgp expression; and D, 10 tumors with negative MRP and Pgp expression. All 40 patients had undergone Tc-TF mammoscintigraphy to calculate breast cancer uptake of Tc-TF to background uptake (T/B) ratios before IHA and surgery/biopsy. Of the four groups, group A had the lowest T/B ratios (1.15+/-0.10) and group D, the highest (2.19+/-0.15) (P<0.05). The T/B ratios in groups B (1.36+/-0.27) and C (1.37+/-0.26) were intermediate between those of groups A and D. In addition, the T/B ratios were statistically significantly lower in group A than in group B or C, and statistically significantly higher in groups D than in groups B or C (P<0.05). However, no significant difference in T/B ratio was found between groups B and C (P>0.05). Our results indicate that Tc-TF mammoscintigraphy is helpful for in vivo determination of Pgp and MRP expression in breast cancers.

Detecting breast cancer in mammographically dense breasts: comparing technetium-99m tetrofosmin mammoscintigraphy and ultrasonography

The aim of our study was to compare the usefulness of technetium-99m tetrofosmin (Tc-TF) mammoscintigraphy and ultrasonography for detecting breast cancer in mammographically dense breasts. This study included 32 female Taiwanese patients with indeterminate mammographic probability of malignancy due to mammographically dense breasts. Both Tc-TF mammoscintigraphy and ultrasonography were performed on each patient. Then, all of the 32 breast masses underwent biopsies or operations to obtain final pathological diagnoses. Based on the final pathological diagnoses, 24 women had breast cancer and eight had benign breast tumors among the 32 patients. Twenty cancers and one benign tumor had positive Tc-TF mammoscintigraphic findings. The sensitivity, specificity, and accuracy were 83, 88, and 84%, respectively. Twenty-two cancers and five benign tumors had positive ultrasonographic findings. The sensitivity, specificity, and accuracy were 92, 38, and 78%, respectively. To detect breast cancer in patients with nondiagnostic mammograms because of mammographically dense breasts, ultrasonography with its higher sensitivity is more suitable for screening breast masses. However, due to its higher specificity, Tc-TF mammoscintigraphy is useful to confirm the ultrasonographic findings.

Usefulness of technetium-99m tetrofosmin scintimammography to detect breast cancer in mammographically dense breasts

The purpose of this study was to assess the usefulness of techentium-99m tetrofosmin (Tc-TF) scintimammography to detect breast cancer in 32 female Taiwanese patients with indeterminate mammograpic probability of malignancy because of mammographyically dense breasts. All breast masses were removed and final histopathological diagnoses were obtained in all cases. The results showed that Tc-TF scintimammography findings were true-positive in 20 cases, false-positive in 1 case, true-negative in seven cases, and false-negative in four cases. The diagnostic sensitivity, specificity, and accuracy were 83, 88, and 84%, respectively, for detecting breast cancer in mammographically dense breasts. In conclusion, Tc-TF scintimammography is a useful tool for detecting breast cancer in patients with indeterminate mammograms 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.

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.

Preliminary observation of 99mTc-thymine imaging in breast neoplasms

New biological knowledge and new diagnostic tools for breast cancer diagnosis may have an important impact on the strategies followed by oncologists in breast cancer management. So far, it has not been possible to label a nucleotide or its precursor with technetium-99m (99mTc) for use in in vivo studies. In this paper, we report the labelling of a precursor, the nitrogenate base thymine, with 99mTc. It has been used to evaluate breast lesions. After animal studies and with the consent of patients, it was employed for evaluation in humans. Thirty-nine women were studied: 32 patients and seven healthy volunteers. Twenty-three malignant lesions showed uptake of labelled thymine. Of the 12 benign cases, there was one false-positive uptake. Labelled thymine was also taken up by one case of malignant microcalcifications. Labelled thymine can be used as a diagnostic method in the identification of malignant anatomo-radiologic palpable lesions of the breast, observed by mammography, possibly avoiding unnecessary biopsies.

Updated audit database for breast imaging/histopathology correlation

AIM

To develop, test and validate an audit database, evolved from a prior, peer-reviewed, audit tool for symptomatic multi-modality breast imaging services.

MATERIALS AND METHODS

The database is to cover all aspects of non-invasive breast imaging and recognize subspeciality inputs. When more than one imaging investigation is used for diagnosis, an overall breast imaging audit grade is to be introduced. Data derived from clinical studies has been input into the new database.

RESULTS

Results for mammography alone are virtually identical to those of the previous program. A slight increase in accuracy is suggested by using more investigations if the first investigation is not conclusive. More comprehensive reports can be issued.

CONCLUSION

The audit program can be used in the same context as the old audit. If mammography is the sole investigation, there is no change from the previous standards of a minimum mammography (ultrasound)/histopathology agreement of 70%, an equivocal rate of less than 15%, a false-positive rate of less than 7.5% and a false-negative rate of less than 6.5%. Although there is no statistical difference when more than one imaging investigation is used, there is some marginal improvement. It is suggested that initial audit standards for multi-imaging should be 75% for minimum agreement, a 10% maximum for an equivocal rate, a 5% maximum for false negative and an unchanged false positive rate of 7.5% maximum. These standards will be refined with experience. Due to the nature of the database, complex queries can be made including those about histopathological data. If widely used, the database will be a useful tool to audit the accuracy of symptomatic breast imaging services and types and frequencies of symptomatic breast disease, as seen in routine settings.

Scintimammography in patients with minimal mammographic or clinical findings

A prospective study was made of scintimammographic findings obtained in 75 patients with minimal mammographic or physical examination findings. Patients included those with a new mammographic nodule or density (n = 33), indeterminate calcifications (n = 15), a palpable abnormality with normal mammographic findings and normal or inconclusive ultrasonographic findings (n = 13), or a new lump or mammographic change at the site of prior surgery (n = 14). A positive scintimammographic focus was defined as a discrete, rounded lesion with increased uptake and could have an intensity ranging from low to very high. Of the 30 cancers diagnosed, 27 demonstrated a positive scintimammographic focus. Eight of these foci represented occult cancers that were not identified at mammography or physical examination, and 11 were smaller than 1 cm (down to 4 mm). The overall sensitivity and specificity of scintimammography were 90% and 93.8%, respectively, which suggests that this modality may be useful in the early detection of breast cancer. It can also help distinguish postsurgical and post-radiation therapy changes from carcinoma and may be of value in certain high-risk patients. Scintimammography is a useful, noninvasive method of evaluating patients with low-suspicion or indeterminate mammographic or palpable findings and can help detect additional small tumors.

99Tc(m)-tetrofosmin scintimammography for detecting breast cancer: a comparative study with 99Tc(m)-MIBI

Scintimammography using 99Tc(m)-MIBI (99Tc(m)-sestamibi) has demonstrated promising results in the detection of breast cancer. Recently scintimammography using 99Tc(m)-tetrofosmin has been suggested as a better diagnostic tool and a more convenient agent to use in this condition. In this study we compared both agents in 35 consecutive women with abnormal mammographic or physical findings. Thirty-four of them underwent MIBI scan, followed by tetrofosmin scan 2 days later (performed on all 35 women). Within 2 weeks, a pathological diagnosis was obtained either by needle or open biopsy. In both scans the uptake ratio between the lesion and the background uptake was calculated. Twenty patients who underwent tetrofosmin scan and 19 patients with MIBI scan had malignant breast tumours, while 15 women had benign lesions. The sensitivity, specificity, positive and negative predictive values and total accuracy of the MIBI scan were 89.4%, 80%, 85%, 85.7% and 85.3%, respectively; almost identical values were obtained with tetrofosmin (90%, 80%, 85.6%, 85.7% and 85.7%, respectively). The uptake ratios in the MIBI and tetrofosmin scans were 1.68 +/- 0.52 and 1.7 +/- 0.47, respectively. No differences were found between the two scintimammographies in all the parameters examined. In conclusion, MIBI and tetrofosmin breast scans are accurate and equally efficient for the detection of breast malignancies.

99m-Tc-tetrofosmin scintigraphy for the evaluation of suspicious palpable and non-palpable breast lesions

PURPOSE

To assess the value of 99m-Tc-tetrofosmin (tetrofosmin) scintigraphy in patients with palpable and nonpalpable breast lesions.

PATIENTS AND METHODS

Prospective, blinded trial. One hundred and fifty-nine consecutive patients with 163 breast lesions detected by clinical examination and mammography were included. Tetrofosmin scintigraphy of the breast was performed additionally to the regular diagnostic procedure. Using histologic assessment as the golden standard, sensitivity, specificity, positive and negative predictive value for tetrofosmin scintigraphy of the breast were assessed.

RESULTS

Overall sensitivity and specificity were 82% and 84%. The sensitivity for palpable tumors (65%) was 93% compared to 62% for non-palpable breast lesions. Malignant lesions were nearly twice as big as benign lesions (31.5 mm +/- 2.4 vs. 16.9 mm +/- 2.4). Specificity, positive and negative predictive value (84%, 89%, and 66%) did not differ significantly in palpable versus non-palpable tumors. Of malignant tumors 18% were found false negative by tetrofosmin scintigraphy.

CONCLUSION

The results suggest that tetrofosmin scintigraphy is a valuable tool for the evaluation of palpable breast cancer. In patients with non-palpable tumors, tetrofosmin scintigraphy may not add to the work-up of patients with breast cancer due to a low sensitivity rate.

Dynamic high-spatial-resolution MR imaging of suspicious breast lesions: diagnostic criteria and interobserver variability

OBJECTIVE

Our study was undertaken to develop diagnostic rules and to assess the reproducibility of dynamic and morphologic parameters for the characterization of suspicious breast lesions using dynamic high-spatial-resolution MR imaging.

MATERIALS AND METHODS

Fifty-seven patients with suspicious mammographic or palpable findings underwent preoperative contrast-enhanced MR imaging of the breast using a three-time-point method of acquisition. Each lesion was prospectively analyzed by two independent radiologists for morphologic and visual dynamic enhancement characteristics. A classification and regression tree was used to examine the optimal order, cutoff points, and combination of imaging parameters to build a diagnostic rule separating benign from malignant lesions using histopathology findings as the standard of reference. Kappa statistics were used to determine observer variability.

RESULTS

Among 23 benign and 34 malignant lesions (12 invasive, three ductal carcinoma in situ, and 19 mixed cancer), margin morphology (p = 0.001) and enhancement pattern (p = 0.001) were the most significant MR imaging findings for lesion characterization. Focal mass lesions were classified as malignant when spiculated margins or both the washout enhancement pattern and "nonsmooth" margins were present. Interobserver agreement was almost perfect for washout pattern and substantial for margin assessment. In the limited population tested retrospectively, the diagnostic rule yielded a sensitivity and positive predictive value of 97% each and a specificity and negative predictive value of 96% each.

CONCLUSION

The washout enhancement pattern combined with lesion margin assessment on dynamic contrast-enhanced high-resolution MR imaging of the breast allows reproducible lesion characterization and may be a highly specific diagnostic tool.

Comparative value of 99mTc-sestamibi scintimammography and sonography in the diagnostic workup of breast masses

OBJECTIVE

This study was conducted to assess the relative roles of 99mTc-sestamibi scintimammography and sonography in the evaluation of breast lesions that are indeterminate or suspicious on mammography or clinical examination.

SUBJECTS AND METHODS

Twenty-five patients with 33 biopsy-proven breast lesions underwent both scintimammography and sonography. Lesions were categorized as benign or requiring biopsy on the basis of the absence or presence of a focus of increased activity on scintimammography and the shape, orientation, and echogenicity of the lesion on sonography.

RESULTS

Sensitivity and specificity in detecting breast cancer were 92% and 95%, respectively, for scintimammography and 100% and 48%, respectively, for sonography. The higher specificity of scintimammography was statistically significant (p < 0.01).

CONCLUSION

Although the overall accuracy of 99mTc-sestamibi scintimammography in the diagnosis of breast cancer was high, it has several disadvantages in comparison with sonography. Scintimammography has a slightly higher false-negative rate for breast cancer, is unable to reveal cysts, is more expensive, takes longer to perform, and involves ionizing radiation. For these reasons, scintimammography with 99mTc-sestamibi is unlikely to either replace sonography or be frequently used in addition to sonography.

Improved uniformity of aortic enhancement with customized contrast medium injection protocols at CT angiography

PURPOSE

To compare the uniformity of aortoiliac opacification obtained from uniphasic contrast medium injections versus individualized biphasic injections at computed tomographic (CT) angiography.

MATERIALS AND METHODS

Thirty-two patients with an abdominal aortic aneurysm underwent CT angiography. In 16 patients (group 1), 120 mL of contrast material was administered at a flow rate of 4 mL/sec. In the other 16 patients (group 2), biphasic injection protocols were computed by using mathematic deconvolution of each patient's time-attenuation response to a standardized test injection. Attenuation uniformity was quantified as the "plateau deviation" of enhancement values, which were calculated as the SD of the time-contiguous attenuation values observed during the 30-second scanning period.

RESULTS

Group 2 patients received between 77 and 165 mL (mean, 115 mL) of contrast medium. Initial flow rates ranged from 4.1 to 10.0 mL/sec (mean, 6.8 mL/sec) for the first 4-6 seconds; continuing flow rates ranged from 2.0 to 4.8 mL/sec (mean, 3.1 mL/sec) for the remaining 24-26 seconds. The plateau deviation was significantly smaller in group 2 patients (19 HU) versus group 1 patients (38 HU, P <.001).

CONCLUSION

At CT angiography, tailored biphasic injections led to more uniform aortoiliac enhancement, compared with standard uniphasic injections of contrast medium.

Axillary metastases of an occult primary carcinoma of the breast-discovered only by 99mTc-tetrofosmin scintigraphy

Recent reports consider 99mTc-tetrofosmin scintigraphy to be a powerful new diagnostic tool for discriminating malignant from benign breast disease. We report on a woman suffering from histologically confirmed axillary metastases of a primary unknown, occult carcinoma, whose origin was suspected within the breast. All the diagnostic procedures performed to discover any lesion failed or were inconclusive. The primary cancer was clearly visualized, however, in the right breast by means of 99mTc-tetrofosmin scintigraphy. Conclusion. We suggest that 99mTc-tetrofosmin scintigraphy is a powerful method to detect breast cancer, especially when other diagnostic imaging procedures are inconclusive.

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.