Mammographic and histologic correlations of microcalcifications

Characterization of Breast Microcalcifications Using a New Ultrasound Image-Processing Technique

OBJECTIVES

To evaluate a new commercial image-processing technique (MicroPure; Toshiba America Medical Systems, Tustin, CA) for detection and characterization of breast microcalcifications in patients undergoing stereotactic or ultrasound-guided biopsies using mammography as the reference standard.

METHODS

One hundred female patients, with a total of 104 lesions, scheduled for an image-guided biopsy of an area with breast microcalcifications (identified on a prior mammogram) underwent MicroPure examinations of the breast using an Aplio XG scanner (Toshiba America Medical Systems) with a broad-bandwidth linear array. MicroPure combines nonlinear imaging and speckle suppression to mark suspected calcifications as white spots in a blue overlay image. Four independent and blinded readers (2 radiologists and 2 physicists) analyzed 208 digital clips consisting of dual grayscale ultrasound and MicroPure imaging, counting the number of microcalcifications seen with MicroPure. The observers also assessed the level of suspicion on a qualitative, visual analog, 6-point scale from 0 (no findings) over 1 (benign) to 5 (malignant).

RESULTS

The mean number of microcalcifications ± SD seen was 6.3 ± 3.5, whereas mammography saw 28.9 ± 24.6 (P = .66). When the MicroPure level of suspicion scores were compared with pathologic results using a receiver operating characteristic curve analysis, the areas under the curve ranged from 0.54 to 0.59. Nonetheless, malignant cases were seen to have significantly more microcalcifications than benign cases (mean number of microcalcifications, 6.9 ± 5.1 versus 5.3 ± 3.7; P = .02).

CONCLUSIONS

MicroPure can be used to identify areas with breast microcalcifications but cannot effectively characterize such areas. Instead, MicroPure may represent a new imaging method for guiding a biopsy to areas of microcalcifications.

New image processing technique for evaluating breast microcalcifications: a comparative study

OBJECTIVES

The purpose of this study was to evaluate a new commercial image processing technique (MicroPure; Toshiba America Medical Systems, Tustin, CA) for identifying breast microcalcifications compared to gray scale ultrasound imaging (US) using mammography as the reference standard.

METHODS

Twenty women, with breast calcifications identified mammographically, underwent gray scale US and MicroPure examinations of the breast. Still images and digital clips of the target area were acquired using gray scale US and MicroPure (at 3 different sensitivity levels: 0, 1, and 2). The images were analyzed by 4 independent and blinded readers (2 radiologists and 2 physicists) to determine the number of calcifications as well as to score image quality and artifacts.

RESULTS

For all 4 readers, there were significantly more calcifications seen with MicroPure (at the 2 highest sensitivity levels) compared to gray scale US (P < .009). Agreement between readers consistently increased from gray scale US to MicroPure imaging (gray scale intraclass correlation coefficient, 0.02-0.44; versus MicroPure intraclass correlation coefficient, 0.34-0.71). The agreement improved between mammography and MicroPure (13.2%-28.3%) when compared with mammography and gray scale US (1.7%-5.2%); the 2 radiologists saw a bigger improvement. Two readers preferred the MicroPure image quality over gray scale US (P < .001) and vice versa for the other 2 readers(P < .001). All 4 readers saw fewer artifacts with MicroPure (at level 2) than with gray scale US (P < .02).

CONCLUSIONS

MicroPure imaging identified significantly more breast microcalcifications than gray scale US.

Mammographic, US, and MR imaging phenotypes of familial breast cancer

PURPOSE

To prospectively investigate the imaging (mammographic, ultrasonographic [US], magnetic resonance [MR] imaging) features of invasive and intraductal breast cancers in women at familial risk.

MATERIALS AND METHODS

Ethics committee approval and informed consent were obtained. Breast cancers were identified in women at moderately increased risk, in women at high familial risk, and in documented BRCA1 and BRCA2 mutation carriers. All cancers were investigated with mammography, US, and bilateral dynamic breast MR imaging. Imaging findings of breast cancer in women in the different risk categories were prospectively collected and compared. With the two-sample Wilcoxon signed rank test, imaging features of cancers were compared.

RESULTS

Seventy-six breast cancers were identified in 68 women (mean age, 41.3 years). Mammographic breast density had no influence on detectability of cancers. Imaging phenotypes differed among risk categories: 15 (23%) of 64 invasive cancers appeared as fibroadenoma-like masses without calcifications but without fibroadenoma-like internal enhancement or enhancement kinetics at breast MR imaging. Of those, 12 (80%) occurred in women at high risk and documented BRCA1 mutation carriers. A posterior (immediately prepectoral) location was observed in 67% (32 of 48) of all breast cancers in women at high risk and mutation carriers (P < .009). None of the remaining BRCA1-associated invasive cancers exhibited calcifications; intraductal cancers were not observed. In 28 cancers in BRCA2 carriers or women at moderately increased risk, imaging features seemed equivalent to those reported for sporadic cancers; cases of ductal carcinoma in situ were observed, and there was no preference for a posterior location in the breast. At MR imaging, a high percentage (20% [13 of 64]) of invasive cancers appeared as non-masslike enhancement; benign kinetic features were observed in 33% (25 of 76).

CONCLUSION

Imaging phenotypes of cancers differ among risk categories. If MR imaging is used for screening, high sensitivity rates are achievable only if morphologic and kinetic features are assessed and if non-masslike enhancement is considered. Lesion location is important in regard to malignancy.

SUPPLEMENTAL MATERIAL

http://radiology.rsnajnls.org/cgi/content/full/246/1/58/DC1.

Intermediate to highly suspicious calcification in breast lesions: a radio-pathologic correlation

Breast calcification is an important feature in the radiological assessment of breast lesions. There are well established diagnostic criteria basing on the morphology and distribution of the calcifications radiologically with recommendation protocols. Pathologically, calcifications in breast lesions are of dystrophic type, and may occur in either the secretory materials or necrotic debris, with inflammation and osteopontin being plausible mediators. Detection of calcium phosphate (hydroyapaptite) is considerably easier than calcium oxalate. Radiologically amorphous calcification represents a borderline type of calcification, and occurs in both benign and malignant (low grade) lesions, and warrants careful follow up and investigation. Clustering of calcification alone may not be an accurate predictor for malignancy, but when there are associated features like pleomorphism, branching, architectural distortion, and associated mass or density, the predictive value for malignant increases. Adequate sampling of calcification in the biopsy is crucial in the management of patients; in general, needle core biopsy or mammotome biopsy achieve satisfactory calcification retrieval. In a benign biopsy that fails to identify the calcifications visible in the mammography, further evaluation or cutting of the histologic block is recommended to minimize the potential of a false negative investigation.

Histological correlation of mammographically detected microcalcifications in stereotactic core biopsies

The aims of this study were to assess the value of specimen radiographs of stereotactic core biopsy, the usefulness of measuring size of calcifications on tissue sections, whether demonstration of calcifications in tissue sections alters the pathological diagnosis when specimen radiograph demonstrates calcifications, and to correlate these assessments with diagnostic outcome. A total of 301 core biopsies from 266 women with 274 mammographically suspicious areas of calcifications were examined. Core biopsies (five cores per procedure) were obtained stereotactically using a 14-gauge needle in an automated Biopty gun. Prior to processing of the tissue, 214 core biopsy specimens from 193 women with 197 lesions were radiographed. Of the 301 core biopsies, 56 (19%) were diagnosed as malignant, 15 (5%) were diagnosed as atypical ductal hyperplasia and 230 (76%) contained benign breast tissue. Of the core biopsies diagnosed as benign, 160 (70%) had specimen radiography prior to processing. Of these, 109 (69%) core biopsies showed calcifications on specimen radiographs. In 96 (88%) of these core biopsies, calcifications measuring > 100 microm were found on the initial tissue sections. In 11 (10%) further deeper sections were required to detect calcifications > 100 microm; however, this did not result in a change of the pathological diagnosis. Two of the 109 (1.8%) "benign" core biopsies, which contained tissue calcifications > 100 microm and at that time were considered representative of the mammographic lesion, have had a malignant outcome on clinical and mammographic follow-up ranging from 2.4 to 7.5 years. Of the 51 (31%) core biopsies where calcifications were not seen on specimen radiographs, histological calcifications were not found in 34 (67%) core biopsies, whereas in 17 (33%) core biopsies, calcifications measuring < 100 microm were found. All of these core biopsies were considered non-diagnostic and therefore not representative of the lesion targeted. Five (9.8%) of these cases had a malignant outcome with either immediate rebiopsy or excision. Accurate diagnosis of all mammographic lesions requires radiological-pathological correlation. This study shows that the presence of calcifications on the specimen radiograph and the demonstration of tissue calcifications > 100 microm are an essential and highly reliable part of core biopsy assessment for mammographically "suspicious" calcifications. Nevertheless, lesions with "highly suspicious" calcifications on mammography should be considered for excision even if the core biopsy diagnosis is benign and calcifications > 100 microm are present.

An automatic method for the identification and interpretation of clustered microcalcifications in mammograms

We investigated a method for a fully automatic identification and interpretation process for clustered microcalcifications in mammograms. Mammographic films of 100 patients containing microcalcifications with known histology were digitized and preprocessed using standard techniques. Microcalcifications detected by an artificial neural network (ANN) were clustered and some cluster features served as the input of another ANN trained to differentiate between typical and atypical clusters, while others were fed into an ANN trained on typical clusters to evaluate these lesions. The measured sensitivity for the detection of grouped microcalcifications was 0.98. For the task of differentiation between typical and atypical clusters an Az value of 0.87 was computed, while for the diagnosis an Az value of 0.87 with a sensitivity of 0.97 and a specificity of 0.47 was obtained. The results show that a fully automatic computer system was developed for the identification and interpretation of clustered microcalcitications in mammograms with the ability to differentiate most benign lesions from malignant ones in an automatically selected subset of cases.

Histologic-radiologic correlation of mammographically detected microcalcification in stereotactic core biopsies

Core biopsy is an alternative technique to surgical excision for assessment of nonpalpable mammographically detected suspicious lesions. The pattern of radiologic calcification is often considered to have diagnostic importance. The aim of this study was to correlate radiologic and histologic features of calcification, with respect to appearance, distribution, and size, to determine the significance, if any, of different radiologic patterns of calcification. Core biopsy samples from 124 women who had 129 mammographically suspicious areas of calcification were examined. Core biopsy samples (five cores per procedure) were obtained stereotactically using a 14-gauge needle in an automated Biopty (Bard Australia, Chatswood, NSW, Australia) gun. In 30 lesions no histologic calcification was found. In the others, there was a poor correlation between radiology and histology with respect to the appearance and distribution of calcification. In a subgroup of 53 women, radiographs of biopsy cores were available to allow correlation with the size of histologic calcification. Calcification of <100 microm assessed histologically was not visible on core biopsy specimen radiographs and may not represent the calcification seen mammographically. Thus, radiography of core biopsy samples and histologic measurement of the size of calcification in core biopsy specimens is useful to reduce false-negative diagnoses in which a biopsy has been performed to evaluate mammographically suspicious calcifications.

Mammographically indeterminate microcalcifications--can we do any better?

In the first round of the mammographic screening program of the South Australian Breast X-ray Service, 80 (0.73%) of the first 10,848 women screened over 18 months were referred after primary and second-stage assessment for definitive histology because of microcalcifications. Obvious mass lesions associated with calcification were excluded from this study, as were women whose calcification was regarded as sufficiently benign to warrant routine rescreening in two years. After classic patterns of malignant microcalcification were excluded, a large group (75%) remained, whose calcifications fell into the indeterminate grades of radiological suspicion. Of these, only 15% proved to have cancer, and in one third of these the cancer was mammographically occult. A high rate of discordant readings was noted in lesions which ultimately proved benign. Neither family history, distribution of calcification nor the presence of a faint soft tissue density proved to be unfailingly reliable predictors of benign or malignant histology in this group. Vigorous pursuit of histopathological correlation and performance statistics are urged to monitor and minimise the proportion of women who remain in this indeterminate group and to follow their natural history. Current mammographic techniques are still inadequate for the provision of definitive information on microcalcification in all cases, but a sustained commitment will reduce the number proceeding to histology for benign disease.