Ancillary Imaging Techniques and Minimally Invasive Procedures in the Diagnosis of Breast Cancer

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Magnetic Resonance Mammography

Magnetic resonance mammography (MRM) is one of the most important additional methods for the diagnosis of breast cancer. The technique is well-described and stan- dardized, with reported sensitivities of about 90% and specificities of about 80%, depending on the indication for which MRM is used.

The MRM-based diagnosis of breast cancer is made ac- cording to certain criteria. The first is the signal intensity on T2-weighted images. Breast cancers have mostly a dark signal intensity, whereas some benign tumors, including cysts and hypercellular fibroadenomas, have a bright sig- nal intensity. The second is the morphologic appearance.

Breast cancers have mostly irregular and spiculated mar- gins whereas benign tumors are usually well-shaped and round. Finally, and perhaps most importantly, the pattern of dynamic contrast enhancement must be well-noted. Breast cancers show an early contrast enhancement with a maxi- mum of more than 100% in the first 3 min, followed by a plateau phenomenon, and a wash-out in the late sequences.

As is the case for screening mammography, the use of a Breast Imaging Reporting and Data System (BIRADS) classification for MRM is recommended (Table 1).

Some authors advocate the use of a point system to evaluate MRM results (Table 2). A visible lesion is as- sessed according to the following criteria, and points are given consistent with the following scheme:

After addition of the points, evaluation is done ac- cording to the scheme shown in Table 3:

The many indications for MRM are summarized be- low. In general, it can be stated that all are well-founded and make use of the high sensitivity of this technique.

Good indications for preoperative MRM in patients with known breast cancers are the detection of multifocal lesions, especially in lobular cancers; detection of con- tralateral carcinoma; monitoring during neoadjuvant chemotherapy; and evaluation of chest-wall invasion.

Good indications for postoperative MRM in breast-can- cer patients are: in the diagnosis of recurrence; postopera- tive tissue reconstruction, e.g., transverse rectus abdomin- is musculocutaneous (TRAM) flap, latissimus dorsi flap;

following silicone augmentation; and after lumpectomy, in

IDKD 2007

Ancillary Imaging Techniques and Minimally Invasive Procedures in the Diagnosis of Breast Cancer

A. Rieber-Brambs

¹

, M. Müller-Schimpfle

²

1Department of Diagnostic and Interventional Radiology and Nuclear Medicine, Municipal Hospitals of Munich GmbH, Hospital Neuperlach, Munich, Germany

2Radiologisches Zentralinstitut, Städt Kliniken Frankfurt/M-Höchst, Frankfurt/Main, Germany

Table 1. The Breast Imaging Reporting and Data System (BIRADS) classification system for magnetic resonance mammography BIRADS level Indication

1 Negative, routine follow-up 2 Benign, routine follow-up

3 Probably benign, short-interval follow-up (6 months)

4 Suspicious, biopsy recommended 5 Highly suggestive of malignancy, biopsy

recommended

0 Additional diagnostic methods recommended

Table 2. Point system for evaluating magnetic resonance mammography results

0 points 1 point 2 points

Shape Round, oval Spiculated, –

irregular

Margins Circumscribed Ill-defined – Contrast Homogeneous Heterogeneous Rim enhancement

Initial contrast <50% 50-100% >100%

enhancement

Post-initial contrast Continuous Plateau Wash-out enhancement

Table 3.BIRADS classification according to points BIRADS level Points Comments

1 0 Negative

2 1-2 Benign

3 3 Probably benign, short-interval

follow-up (6 months)

4 4-5 Suspicious, biopsy recommended

5 6-8 Highly suggestive of malignancy,

biopsy recommended 195_198_Rieber_Brambs 6-03-2007 15:04 Pagina 195

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the evaluation of patients with close or positive margins for residual disease.

Beside these indications, MRM can be recommended in the following cases:

– Axillary lymph-node metastases in unknown primary – Patients with familial disposition for breast cancer – Asymmetric opacity in mammography

– Suspicious retraction of the nipple without pathologic findings on mammography and sonography

– Abnormal ductal lavage cytology with negative physi- cal examination, mammography, and ultrasound.

Nevertheless, the specificity of MRM is limited, which often precludes the reliable differentiation between be- nign and malignant lesions. In these cases, core needle biopsy or follow-up after 6 months are the methods of choice. MRM is usually not recommended in the differ- ential diagnosis of fibroadenoma/carcinoma or inflam- matory carcinoma/mastitis. In both of these cases, biop- sy is the diagnostic method of choice. MRM is also not used in the diagnosis of non-invasive breast cancer, as here again biopsy is preferred. Biopsy or follow-up is recommended in the differential diagnosis of liponecro- sis/recurrence in flaps. Mastopathic lesions that mimic carcinoma should be carefully followed. Surgery is re- commended for those patients in whom tumor size fol- lowing chemotherapy cannot be reliably determined. In the evaluation of scarring at <6 months, further evalua- tion or biopsy should be considered. The success of ra- diotherapy at a follow-up of 6 months should either be determined by biopsy or the waiting time should be ex- tended before the patient’s status is assessed.

Positron Emission Tomography

Positron emission tomography (PET) is a very promising method in oncology patients. Nevertheless, its use is limi- ted in breast-cancer patients, and currently there are no rou- tine indications in these patients. The main reason is the limited sensitivity (78.9%) of PET in the diagnosis of breast cancer. However, there are other reasons that justify the limi- ted use of PET. For example, in the detection of multifocal lesions in breast cancer, MRM has a higher sensitivity than PET. In the diagnosis of axillary lymph-node metastases, sentinel node scintigraphy is superior to PET. As with MRM, false-negative results are reported in patients with a good response to chemotherapy. The reliable differentiation between mastitis and chemotherapy is not possible.

In summary, many further studies are still necessary before the use of PET in breast-cancer patients can be recommended with confidence.

Minimally Invasive Procedures

In most unclear cases, especially if the lesion is more or less suspicious, biopsy is necessary to obtain a definitive reliable diagnosis. Several biopsy methods are available:

196

– Fine-needle aspiration cytology (FNAC; 18-25 G needle) – Core needle biopsy (CNB; 14-16 G needle)

– Vacuum-assisted biopsy (extirpation of lesions

≤

1 cm in diameter; 11-14 G needle

– ‘Advanced Breast Biopsy Instrumentation’ (ABBI):

extirpation of lesions 5-20 mm in diameter.

The results of FNAC are limited. Instead, CNB or oth- er techniques involving the use of thicker needles are re- commended. A comparison of FNAC and CNB is shown in Table 4.

The results of vacuum-assisted biopsy are superior to these of CNB, which accounts for its increasing use.

ABBI has also shown promising results, but the compli- cation rate is high, making the use of this method prob- lematic. Thicker needles allow histological evaluation to be made with greater diagnostic accuracy, nevertheless, tumors may still be histologically underestimated: In CNB (14-G needle) this occurs in about 20.4% of cases and in vacuum-assisted biopsy (11-G needle) in about 11.2% of cases, depending on the number of biopsies performed. For ten biopsies underestimation was 17.5%, while for more than ten biopsies the rate was 11.5%.

Currently, several considerations must be made re- garding the use of percutaneous stereotactic vacuum-as- sisted biopsy. First, it is a diagnostic method, not a form of therapy. Thus, in histologically proven cancers the tu- mor must be surgically resected. BIRADS 1 and 2 are not indications for the use of this biopsy technique, while in BIRADS 3 it should be undertaken only after extensive discussion with the patient. For BIRADS 4, biopsy is obligatory but the most appropriate method should be chosen by the treating physician. For BIRADS 5, CNB is sufficient for confirmation of breast cancer and planning of surgical therapy. Vacuum-assisted biopsy is, however, recommended for clip-placement in patients receiving neoadjuvant chemotherapy and following complete extir- pation of the lesion, in most cases.

About 40 min are required to perform a vacuum- assisted biopsy. Complete extirpation following assisted biopsy was reported in 32.5-61% of patients.

Representative probes were obtained in 39-77.5% of the biopsies and no scars were visible by mammography in 96% of the patients.

Conclusions

The high sensitivity of MRM recommends its use for the detection of multifocal lesions or contralateral carcinoma

A. Rieber-Brambs, M. Müller-Schimpfle

Table 4. Comparison of fine-needle aspiration cytology (FNAC) and core needle biopsy (CNB)

FNAC CNB

Sensitivity (%) 85-88 91-98

Specificity (%) 55.6-90.5 73-100

Accuracy (%) 53.8-67.3 79-97

195_198_Rieber_Brambs 28-02-2007 07:39 Pagina 196

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in known breast cancer or for the exclusion or detection of recurrent disease. PET is a promising method, but, at least for now, its use is restricted to clinical studies.

In the evaluation of most unclear or suspicious lesions, biopsy is recommended because the differentiation be- tween benign and malignant lesions is limited with all imaging modalities. Vacuum-assisted biopsy seems to be superior to all other techniques, including FNAC, CNB, or ABBI. Nevertheless, to confirm a diagnosis of breast cancer or in the planning of surgical therapy CNB is usu- ally sufficient.

Ancillary Imaging Techniques and Minimally Invasive Procedures in the Diagnosis of Breast Cancer

Magnetic Resonance Mammography

Magnetic resonance mammography (MRM) is one of the most important additional methods for the diagnosis of breast cancer. The technique is well-described and stan- dardized, with reported sensitivities of about 90% and specificities of about 80%, depending on the indication for which MRM is used.

As is the case for screening mammography, the use of a Breast Imaging Reporting and Data System (BIRADS) classification for MRM is recommended (Table 1).

Some authors advocate the use of a point system to evaluate MRM results (Table 2). A visible lesion is as- sessed according to the following criteria, and points are given consistent with the following scheme:

After addition of the points, evaluation is done ac- cording to the scheme shown in Table 3:

The many indications for MRM are summarized be- low. In general, it can be stated that all are well-founded and make use of the high sensitivity of this technique.

Good indications for preoperative MRM in patients with known breast cancers are the detection of multifocal lesions, especially in lobular cancers; detection of con- tralateral carcinoma; monitoring during neoadjuvant chemotherapy; and evaluation of chest-wall invasion.

Good indications for postoperative MRM in breast-can- cer patients are: in the diagnosis of recurrence; postopera- tive tissue reconstruction, e.g., transverse rectus abdomin- is musculocutaneous (TRAM) flap, latissimus dorsi flap;

following silicone augmentation; and after lumpectomy, in

IDKD 2007

Ancillary Imaging Techniques and Minimally Invasive Procedures in the Diagnosis of Breast Cancer

A. Rieber-Brambs

, M. Müller-Schimpfle

the evaluation of patients with close or positive margins for residual disease.

Beside these indications, MRM can be recommended in the following cases:

– Axillary lymph-node metastases in unknown primary – Patients with familial disposition for breast cancer – Asymmetric opacity in mammography

– Suspicious retraction of the nipple without pathologic findings on mammography and sonography

– Abnormal ductal lavage cytology with negative physi- cal examination, mammography, and ultrasound.

Positron Emission Tomography

In summary, many further studies are still necessary before the use of PET in breast-cancer patients can be recommended with confidence.

Minimally Invasive Procedures

In most unclear cases, especially if the lesion is more or less suspicious, biopsy is necessary to obtain a definitive reliable diagnosis. Several biopsy methods are available:

– Fine-needle aspiration cytology (FNAC; 18-25 G needle) – Core needle biopsy (CNB; 14-16 G needle)

– Vacuum-assisted biopsy (extirpation of lesions

1 cm in diameter; 11-14 G needle

– ‘Advanced Breast Biopsy Instrumentation’ (ABBI):

extirpation of lesions 5-20 mm in diameter.

The results of FNAC are limited. Instead, CNB or oth- er techniques involving the use of thicker needles are re- commended. A comparison of FNAC and CNB is shown in Table 4.

The results of vacuum-assisted biopsy are superior to these of CNB, which accounts for its increasing use.

About 40 min are required to perform a vacuum- assisted biopsy. Complete extirpation following assisted biopsy was reported in 32.5-61% of patients.

Representative probes were obtained in 39-77.5% of the biopsies and no scars were visible by mammography in 96% of the patients.

Conclusions

The high sensitivity of MRM recommends its use for the detection of multifocal lesions or contralateral carcinoma

in known breast cancer or for the exclusion or detection of recurrent disease. PET is a promising method, but, at least for now, its use is restricted to clinical studies.

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