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

Detection and diagnosis of automated breast ultrasound in patients with BI-RADS category 4 microcalcifications: a retrospective study

BACKGROUND

Automated Breast Ultrasound (AB US) has shown good application value and prospects in breast disease screening and diagnosis. The aim of the study was to explore the ability of AB US to detect and diagnose mammographically Breast Imaging Reporting and Data System (BI-RADS) category 4 microcalcifications.

METHODS

575 pathologically confirmed mammographically BI-RADS category 4 microcalcifications from January 2017 to June 2021 were included. All patients also completed AB US examinations. Based on the final pathological results, analyzed and summarized the AB US image features, and compared the evaluation results with mammography, to explore the detection and diagnostic ability of AB US for these suspicious microcalcifications.

RESULTS

250 were finally confirmed as malignant and 325 were benign. Mammographic findings including microcalcifications morphology (61/80 with amorphous, coarse heterogeneous and fine pleomorphic, 13/14 with fine-linear or branching), calcification distribution (189/346 with grouped, 40/67 with linear and segmental), associated features (70/96 with asymmetric shadow), higher BI-RADS category with 4B (88/120) and 4 C (73/38) showed higher incidence in malignant lesions, and were the independent factors associated with malignant microcalcifications. 477 (477/575, 83.0%) microcalcifications were detected by AB US, including 223 malignant and 254 benign, with a significantly higher detection rate for malignant lesions (x2 = 12.20, P < 0.001). Logistic regression analysis showed microcalcifications with architectural distortion (odds ratio [OR] = 0.30, P = 0.014), with amorphous, coarse heterogeneous and fine pleomorphic morphology (OR = 3.15, P = 0.037), grouped (OR = 1.90, P = 0.017), liner and segmental distribution (OR = 8.93, P = 0.004) were the independent factors which could affect the detectability of AB US for microcalcifications. In AB US, malignant calcification was more frequent in a mass (104/154) or intraductal (20/32), and with ductal changes (30/41) or architectural distortion (58/68), especially with the both (12/12). BI-RADS category results also showed that AB US had higher sensitivity to malignant calcification than mammography (64.8% vs. 46.8%).

CONCLUSIONS

AB US has good detectability for mammographically BI-RADS category 4 microcalcifications, especially for malignant lesions. Malignant calcification is more common in a mass and intraductal in AB US, and tend to associated with architectural distortion or duct changes. Also, AB US has higher sensitivity than mammography to malignant microcalcification, which is expected to become an effective supplementary examination method for breast microcalcifications, especially in dense breasts.

A Nomogram for Enhancing the Diagnostic Effectiveness of Solid Breast BI-RADS 3-5 Masses to Determine Malignancy Based on Imaging Aspects of Conventional Ultrasonography and Contrast-Enhanced Ultrasound

BACKGROUND

To establish and validate a nomogram model, which can incorporate clinical data, and imaging features of ultrasound (US) and contrast-enhanced ultrasound (CEUS), for improving the diagnostic efficiency of solid breast lesions.

PATIENTS AND METHODS

A total of 493 patients with solid breast lesions were randomly divided into training (n = 345) and validation (n = 148) cohorts with a ratio of 7:3 and, clinical data and image features of US and CEUS were reviewed and retrospectively analyzed. The breast lesions in both the training and validation cohorts were analyzed using the BI-RADS and nomogram models.

RESULTS

Five variables, including the shape and calcification features of conventional US, enhancement type and size after enhancement features of CEUS, and BI-RADS, were selected to construct the nomogram model. As compared to the BI-RADS model, the nomogram model demonstrated satisfactory discriminative function (area under the receiver operating characteristic [ROC] curves [AUC], 0.940; 95% confidence interval [CI], 0.909 to 0.971; sensitivity, 0.905; and specificity, 0.902 in the training cohort and AUC, 0.968; 95% CI, 0.941 to 0.995; sensitivity, 0.971; and specificity, 0.867 in the validation cohort). In addition, the nomogram model showed good consistency and clinical potential according to the calibration curve and DCA.

CONCLUSION

The nomogram model could identify benign from malignant breast lesions with good performance.

Clinical Utility of MicroPure US Imaging for Breast Microcalcifications

Purpose

To evaluate the performance of MicroPure US imaging to detect and characterize microcalcifications.

Materials and Methods

A total of 171 lesions with suspicious microcalcifications seen on mammography and B-mode US were included and simultaneously evaluated using MicroPure US imaging. The size of microcalcifications was divided into small (punctate, amorphous, fine pleomorphic, and fine linear) and large (coarse heterogeneous), and the extent was divided into narrow (grouped) and wide (others). MicroPure US imaging visibility was divided into four types based on the number of microcalcifications on the two images: B > M (more on B-mode), B = M (similar), B < M (more on MicroPure), and negative. Triple pairwise comparison was used to evaluate the imaging features according to the MicroPure US imaging visibility.

Results

Among the 171 lesions examined, 157 lesions (91.8%) were detected by MicroPure US imaging. The proportion of Breast Imaging Reporting and Data System (BI-RADS) category 4A was significantly higher in the MicroPure positive group, and that of category 4B was significantly higher in the MicroPure negative group (p = 0.035). The other imaging features did not differ. Among the positive MicroPure subgroups, all features showed no significant difference.

Conclusion

MicroPure US imaging demonstrated 91.8% positivity in detecting microcalcifications on B-mode US. MicroPure US imaging visibility correlated with the BI-RADS category of microcalcifications.

Usability of Ultrasonic MicroPure Imaging for Evaluating the Vulnerability of Carotid Atherosclerotic Plaques

OBJECTIVE

MicroPure is an ultrasound imaging technology used for detecting microcalcifications. This study aimed to evaluate the usefulness of the Firefly sign in ultrasonic MicroPure imaging for detecting the vulnerability of carotid plaques.

METHODS

Ultrasonic grey-scale imaging was used to detect carotid plaques. Ultrasonic MicroPure imaging was used to detect the Firefly sign and to determine the location and number of Firefly signs.

RESULTS

A total of 142 plaques were detected in 72 patients, and 62.0% were Firefly-positive plaques. The length or thickness, the risk of rupture and the percentage of vulnerable plaques were greater in the Firefly-positive plaques than in Firefly-negative plaques. The assessment of plaque vulnerability built on the 4-point Firefly scoring system showed that the area under the ROC curve was 0.750 (P < .001). The sensitivity and specificity of vulnerable plaques with a score of 2 points were 71.9 and 73.6%, respectively.

CONCLUSION

The Firefly signs are widely present in carotid atherosclerotic plaques and can be detected with ultrasonic MicroPure imaging. Firefly signs located in fibrous caps may be associated with plaque vulnerability.

Advances in Ultrasound-Guided Vacuum-Assisted Biopsy of Breast Microcalcifications

Microcalcification is one of the significant indications for or can even be the sole mammographic feature of breast cancer, especially occult breast cancer. Biopsy and pathologic examination are the most important methods used to identify the nature of suspicious microcalcifications. Stereotactic vacuum-assisted breast biopsy (S-VAB) is the most commonly used biopsy method for microcalcifications currently because of the high detection rate of mammography for microcalcifications. However, in recent years, several clinical studies have gradually found that ultrasound-guided vacuum-assisted breast biopsy (US-VAB) could be an alternative to S-VAB for microcalcifications to some extent, and has its own advantages of flexibility, real-time performance, comfort and high accessibility compared with mammography. An overview of US-VAB of microcalcifications is provided with respect to success rate, diagnostic accuracy, advantages and limitations. On the basis of numerous studies and clinical experience, US-VAB proved to be a valid alternative to S-VAB, with comparable diagnostic accuracy if the microcalcification foci could be detected by ultrasound. And for patients with ultrasound-invisible microcalcifications who are not suitable for or tolerable of S-VAB, US-VAB combined with mammography localization of microcalcifications can also be considered.

The ability of Micropure® ultrasound technique to identify microcalcifications in carotid plaques

OBJECTIVES

To study the ability of Micropure® ultrasound technique to identify microcalcifications in carotid plaques.

METHODS

Forty-four carotids in 22 patients were enrolled in this study and were detected by routine ultrasound examination and Micropure® examination at the same time to identify microcalcifications in plaques. The results were compared with the tissue-background ratio (TBR) in ¹⁸F-NaF PET-CT imaging, which was performed one or two days after the ultrasound examination.

RESULTS

In the 44 carotids, plaques were detected in 37 carotids. Microcalcifications were detected by the Micropure® technique in 32 carotids, which were located surrounded by macrocalcifications in 23 carotids, in the fibre cap in 12 carotids, and in the base of the plaque in 6 carotids. Microcalcifications were not detected in 12 carotids. In ¹⁸F-NaF PET-CT examination, TBR > 1.61 (range 1.62-3.99, mean 2.25 ± 0.58) was detected in 37 carotids, and TBR < 1.61 was detected in 7 carotids. There were no significant differences between the two methods in detecting microcalcifications (p = 0.180). The sensitivity of the Micropure® technique in detecting microcalcifications was 81.08 %, and the specificity was 71.43 %.

CONCLUSIONS

Microcalcifications in the carotid artery detected by the Micropure® technique were well in accordance with ¹⁸F-NaF PET-CT scanning, with better sensitivity and specificity.

Value of contrast-enhanced ultrasound in the diagnosis of breast US-BI-RADS 3 and 4 lesions with calcifications

AIM

To evaluate the diagnostic performance of contrast-enhanced ultrasound (CEUS) for Breast Imaging-Reporting and Data System for Ultrasound (US-BI-RADS) 3 and 4 lesions with calcifications.

MATERIALS AND METHODS

A retrospective study of 168 breast lesions with calcifications detected on both mammography and conventional ultrasonography (US) in 152 patients were categorised as US-BI-RADS 3-4 at US between June 2009 and June 2018. CEUS scores were obtained based on a CEUS five-point scoring system. The combination of US-BI-RADS and CEUS scores created the Rerated BI-RADS (referred to as CEUS-BI-RADS). All results were compared with the histological findings. The diagnostic performances of US and CEUS-BI-RADS were compared.

RESULTS

The diagnostic sensitivity, specificity, and accuracy of US were 81.8% (95% confidence interval [CI]: 71.6%, 92%), 85% (95% CI: 78.4%, 91.5%), and 83.9% (95% CI: 78.4%, 89.5%), respectively, while those for CEUS-BI-RADS were 98.2% (95% CI: 94.7%, 100%), 90.3% (95% CI: 84.8%, 95.7%), and 92.9% (95% CI: 89%, 96.8%), respectively. The diagnostic sensitivity and accuracy values of CEUS-BI-RADS greatly improved compared with those of US (p=0.003 and p=0.004, respectively). The areas under the receiver operating characteristic (ROC) curves for US and CEUS-BI-RADS were 0.888 (95% CI: 0.840, 0.936) and 0.963 (95% CI: 0.936, 0.989), respectively. The diagnostic efficacy of CEUS-BI-RADS was significantly higher than that of US alone (p=0.004).

CONCLUSION

CEUS-BI-RADS significantly improves the diagnostic accuracy for breast US-BI-RADS 3 and 4 lesions with calcifications compared with US.

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.

Improving Spatial Resolution Using Incoherent Subtraction of Receive Beams Having Different Apodizations

In ultrasonic imaging, reduction of lateral sidelobes can result in an improved image with less distortion and fewer artifacts. In general, apodization is used to lower sidelobes in exchange for increasing the width of the main lobe, and thus decreasing lateral resolution. Null subtraction imaging (NSI) is a nonlinear image processing technique that uses different receive apodizations on copies of the same RF data to maintain low sidelobe levels while simultaneously improving lateral resolution. The images created with three different apodization functions are combined to form an image with low sidelobe levels and apparent improvements in lateral resolution compared to conventional rectangular apodization. To evaluate the performance of this technique for different imaging tasks, experiments were performed on an ATS539 phantom containing wire targets to assess lateral resolution and cylindrical anechoic and hyperechoic targets to assess contrast. NSI images were compared against rectangular apodized images and minimum variance beamformed images. In experiments, the apparent lateral resolution was observed to improve by a factor of more than 35× when compared to rectangular apodization. Image quality was assessed by the estimation of lateral resolution (-6-dB receive beamwidth), main-lobe-to-sidelobe ratio, and contrast-to-noise ratio (CNR). Imaging with NSI using a focal number of 2 (f/2), the -6-dB beamwidth on receive as measured from a small wire target in the ATS phantom was 0.03λ compared to 2.79λ for rectangular apodization. Sidelobes were observed to decrease by 32.9 dB with NSI compared to rectangular apodization. However, the ability to observe the contrast of anechoic and hyperechoic targets reduced when utilizing the NSI scheme, i.e., the CNR decreased from -3.05 to -1.01 for anechoic targets and 1.65 to 0.45 for the hyperechoic targets.

Ultrasound Detection of Microcalcifications in Surgical Breast Specimens

The objective was to evaluate a commercial image processing technique (MicroPure, Canon Medical Systems, Tustin, CA, USA) for detection of microcalcifications in breast surgical specimens. Twenty women scheduled for surgical excision of an area with breast calcifications were enrolled, their surgical specimens underwent grayscale ultrasound (US) and MicroPure examination using an Aplio XG scanner (Canon). Four independent and blinded readers analyzed 54 US and 54 MicroPure digital clips to determine the number of calcifications and scored image quality and artifacts on a 10-point scale. All readers saw significantly more microcalcifications with MicroPure than with US, 14.0 ± 12.0 versus 3.0 ± 3.2 (p <0.0001). Three readers preferred MicroPure image quality over that of US (p <0.009) and vice versa for one reader (p = 0.003). Three readers saw fewer Cooper's ligament artifacts with MicroPure than with US (p <0.0001); one reader saw no significance difference between them (p = 0.58). In conclusion MicroPure identified more breast microcalcifications than grayscale US in ex vivo surgical breast specimens.

Recent technological advancements in breast ultrasound

Ultrasound is becoming increasingly common as an imaging tool for the detection and characterization of breast tumors. This paper provides an overview of recent technological advancements, especially those that may have an impact in clinical applications in the field of breast ultrasound in the near future. These advancements include close to 100% fractional bandwidth high frequency (5-18MHz) 2D and 3D arrays, automated breast imaging systems to minimize the operator dependence and advanced processing techniques, such as those used for detection of microcalcifications. In addition, elastography and contrast-enhanced ultrasound examinations that are expected to further enhance the clinical importance of ultrasound based breast tumor screening are briefly reviewed. These techniques have shown initial promise in clinical trials and may translate to more comprehensive clinical adoption in the future.

The Utility of MicroPure™ Ultrasound Technique in Assessing Grouped Microcalcifications without a Mass on Mammography

The term "grouped microcalcifications" refers to the smallest arrangement of a relatively few calcifications noted on mammography, and has a wide range of clinical associations. For the pathologic diagnosis of suspicious-looking grouped microcalcifications without an associated mass, a mammography-guided procedure should be considered, because visualization of microcalcifications by conventional ultrasound (US) is limited. A mammography-guided procedure requires radiation exposure, is associated with pain, and is more time-consuming to perform than an US-guided procedure. However, an innovative US technology called MicroPure™ (Toshiba Medical Systems Corp., Tokyo, Japan) imaging improves detection and visualization of microcalcifications. We demonstrate the early clinical experience with and utility of MicroPure US examination of 10 breast lesions involving grouped microcalcifications without a mass on mammography screening.

Comparison of automated breast ultrasonography to handheld ultrasonography in detecting and diagnosing breast lesions

BACKGROUND

Automated breast ultrasonography (ABUS) is increasingly used as a screening tool. Several studies have demonstrated a similar diagnostic performance for ABUS compared with handheld ultrasonography (HHUS), but the overall results have been controversial.

PURPOSE

To compare the clinical utility of ABUS and HHUS for detection and diagnosis of breast lesions.

MATERIAL AND METHODS

ABUS and HHUS images of suspicious breast lesions were obtained for 173 consecutive women scheduled to undergo ultrasonography (US)-guided or stereotactic biopsy. There were a total of 206 lesions, 46 of which were malignant and 160 benign. Three breast radiologists took part in this study: two reviewed the ABUS images, and the third reviewed all of the images, ABUS and HHUS, as well as the patients' medical records. The biopsied-lesion-detection rates were obtained. Using the Breast Imaging Reporting and Data System (BI-RADS), the images of the biopsied lesions were evaluated. Factors affecting ABUS detectability were analyzed.

RESULTS

The overall detection rates were 83.0% for ABUS and 94.2% for HHUS. Ten lesions were not detected on either HHUS or ABUS and these were microcalcifications (one malignancy and nine benign lesions). Of the 194 HHUS-detected lesions, 169 were detected by ABUS and 25 benign were not. ABUS less frequently detected lesions of smaller size as well as those of benign appearance and lower final-assessment category (P = 0.011 and P < 0.0001, respectively).

CONCLUSION

ABUS detected all of the malignant lesions that were detected on HHUS. ABUS missed several smaller benign lesions.

The Diagnostic Value of Micropure Imaging in Breast Suspicious Microcalcificaion

RATIONALE AND OBJECTIVES

The purpose of this study was to evaluate the diagnostic value of Micropure Imaging (MI) in breast lesions differentiation by comparison with B-mode ultrasonography (B-US) and Doppler ultrasonography (DU).

MATERIALS AND METHODS

A total of 135 consecutive patients (all females) with 135 suspicious lesions were examined and skin marked by MI before mammotome biopsies. All patients (age range, 20-86 years; mean age, 42.5 ± 15.6 years) were the first onset, not in the pregnancy or lactation and had no history of radiation or chemotherapy. The maximum diameter of lesions ranged from 0.2 to 9.6 cm (average 1.98 ± 1.3 cm). Their final diagnoses were obtained by histologic examination. The study protocol was approved by the hospital review board; each patient gave written informed consent.

RESULTS

One hundred thirty-five breast lesions were classified into 90 nonmalignant and 45 malignant types. To 86 breast lesions with microcalcification, MI showed more microcalcification and coincided better with pathology results than B-US did (P < .05). The specificity of MI was higher than that of B-US and DU; the sensitivity of DU was significantly higher than that of B-US and MI (P < .001). By combining B-US, DU, and MI, the detection accuracy was 86.7%. Receiver-operator characteristic curves showed the area under the curve of B-US, DU, and MI was 0.865, 0.934, and 0.923(P = .000), respectively. Moreover, the interobserver agreements of MI were the highest, 0.922 (observer 1 vs. observer 2), 0.866 (observer 1 vs. observer 3), and 0.916 (observer 2 vs. observer 3).

CONCLUSIONS

MI as an adjunct ultrasound modality holds some promise in locating and differentiating breast lesions.

Thyroid nodule ultrasound: technical advances and future horizons

Thyroid nodules are extremely common and the vast majority are non-malignant; therefore the accurate discrimination of a benign lesion from malignancy is challenging. Ultrasound (US) characterisation has become the key component of many thyroid nodule guidelines and is primarily based on the detection of key features by high-resolution US. The thyroid imager should be familiar with the strengths and limitations of this modality and understand the technical factors that create and alter the imaging characteristics. Specific advances in high-resolution US are discussed with reference to individual features of thyroid cancer and benign disease. Potential roles for three-dimensional thyroid ultrasound and computer-aided diagnosis are also considered. The second section provides an overview of current evidence regarding thyroid ultrasound elastography (USE). USE is a novel imaging technique that quantifies tissue elasticity (stiffness) non-invasively and has potential utility because cancers cause tissue stiffening. In recent years, there has been much research into the value of thyroid USE for distinguishing benign and malignant nodules. Preliminary findings from multiple pilot studies and meta-analyses are promising and suggest that USE can augment the anatomical detail provided by high-resolution US. However, a definite role remains controversial and is discussed.

TEACHING POINTS

• High-resolution US characterises thyroid nodules by demonstration of specific anatomical features • Technical advances heavily influence the key US features of thyroid nodules • Most papillary carcinomas appear stiffer than benign thyroid nodules on US elastography (USE) • Thyroid USE is controversial because of variation in the reported accuracies for malignancy • Combined grey-scale US/USE may lower the FNAC rate in benign nodules.

Microcalcifications versus artifacts: initial evaluation of a new ultrasound image processing technique to identify breast microcalcifications in a screening population

A new commercial image processing technique (MicroPure, Toshiba America Medical Systems, Tustin, CA, USA) that identifies breast microcalcifications was evaluated at the time of patients' annual screening mammograms. Twenty women scheduled for annual screening mammography were enrolled in the study. Patients underwent bilateral outer-upper-quadrant real-time dual gray scale ultrasound and MicroPure imaging using an Aplio XG scanner (Toshiba). MicroPure combines non-linear imaging and speckle suppression to mark suspected calcifications as white spots in a blue overlay image. Four independent and blinded readers analyzed digital clips to determine the presence or absence of microcalcifications and artifacts. The presence of microcalcifications determined by readers was not significantly different from that of mammography (p = 0.57). However, the accuracy was low overall (52%) and also in younger women (<50 years, 54%). In conclusion, although microcalcifications can be identified using MicroPure imaging, this method is not currently appropriate for a screening population and should be used in more focused applications.

Photoacoustic imaging of breast microcalcifications: a preliminary study with 8-gauge core-biopsied breast specimens

Background

We presented the photoacoustic imaging (PAI) tool and to evaluate whether microcalcifications in breast tissue can be detected on photoacoustic (PA) images.

Methods

We collected 21 cores containing microcalcifications (n = 11, microcalcification group) and none (n = 10, control group) in stereotactic or ultrasound (US) guided 8-gauge vacuum-assisted biopsies. Photoacoustic (PA) images were acquired through ex vivo experiments by transmitting laser pulses with two different wavelengths (700 nm and 800 nm). The presence of microcalcifications in PA images were blindly assessed by two radiologists and compared with specimen mammography. A ratio of the signal amplitude occurring at 700 nm to that occurring at 800 nm was calculated for each PA focus and was called the PAI ratio.

Results

Based on the change of PA signal amplitude between 700 nm and 800 nm, 10 out of 11 specimens containing microcalcifications and 8 out of 10 specimens without calcifications were correctly identified on blind review; the sensitivity, specificity, accuracy, positive predictive and negative predictive values of our blind review were 90.91%, 80.0%, 85.71%, 83.33% and 88.89%. The PAI ratio in the microcalcification group was significantly higher than that in the control group (the median PAI ratio, 2.46 versus 1.11, respectively, P = .001). On subgroup analysis in the microcalcification group, neither malignant diagnosis nor the number or size of calcification-foci was proven to contribute to PAI ratios.

Conclusion

Breast microcalcifications generated distinguishable PA signals unlike breast tissue without calcifications. So, PAI, a non-ionizing and non-invasive hybrid imaging technique, can be an alternative in overcoming the limitations of conventional US imaging.