A Multireader Multicase (MRMC) Receiver Operating Characteristic (ROC) Study Evaluating Noninferiority of Quantitative Transmission (QT) Ultrasound to Digital Breast Tomosynthesis (DBT) on Detection and Recall of Breast Lesions

RATIONALE AND OBJECTIVES

Quantitative transmission (QT) imaging is an emerging volumetric ultrasound modality for women too young for mammography. QT images tissue without overlap seen in mammography, thereby can potentially improve breast mass detection and characterization and noncancer recall. We compared radiologists' interpretation of QT vs digital breast tomosynthesis (DBT) with a multireader multicase observer performance study.

MATERIALS AND METHODS

Study subjects received screening DBT and QT scans in HIPAA-compliant, institutional review board-approved prospective case-collection studies at four clinical sites. Twenty-four Mammography Quality Standards Act-qualified radiologists interpreted 177 cases (66 with cancer, atypia, or solid mass and 111 normal or with nonsolid benign abnormality), first QT, then 2 weeks later DBT synthesized 2D-views. Readers reported up to three findings per case and for each finding a recall or no recall decision and confidence of that decision. The study hypothesis was area under receiver operating characteristic curve (AUC) of QT was noninferior to DBT. Sensitivity and specificity were also compared.

RESULTS

AUC of QT (0.746 ± 0.028, mean ± SD) was noninferior to DBT (0.700 ± 0.028) for AUC difference margin of -0.05 (P < .05). AUC difference was 0.046 ± 0.028 (95% CI: [-0.008, 0.101]). Sensitivity was 70.6 ± 7.2% for QT and 85.2 ± 6.4% for DBT, specificity was 60.1 ± 12.3% vs 37.2 ± 11.0%, and both differences were statistically significant. Of a total of 21 cases of cysts, readers recommended recall, on average, in 1.1 ± 1.4 cases with QT, but not with DBT, and 10.6 ± 2.2 cases with DBT, but not with QT.

CONCLUSION

QT can be a potential alternative to mammography for breast cancer screening of women too young to undergo mammography.

An Exploratory Multi-reader, Multi-case Study Comparing Transmission Ultrasound to Mammography on Recall Rates and Detection Rates for Breast Cancer Lesions

BACKGROUND

Three-dimensional Quantitative Transmission (QT) ultrasound imaging is an emerging modality for improving the detection and diagnosis of breast cancer. QT ultrasound has high resolution and high contrast to noise ratio, making it effective in evaluating breast tissue. This study compares radiologists' performance of noncancer recall rates and lesion detection rates using QT Ultrasound versus full-field digital mammography (FFDM) in a cross section of female subjects.

MATERIALS AND METHODS

In this multi-reader multi-case (MRMC) study, we examined retrospective data from two clinical trials conducted at five sites. All subjects received FFDM and QT scans within 90 days. Data were analyzed in a reader study with full factorial design involving 22 radiologists and 108 breast cases (42 normal, 39 pathology-confirmed benign, and 27 pathology-confirmed cancer cases). The main results used a random-reader random-case analysis adjusted for location bias performed after a primary predefined random-reader fixed-case analysis.

RESULTS

The readers' mean rate of detecting lesions of any type was 4% higher (p-value > 0.05) with QT imaging. The mean non-cancer recall rate improved significantly, showing a decrease of 16% with QT (p-value = 0.03), at the expense of a 2% decrease in the mean cancer recall rate (p-value >0.05) in comparison to FFDM. Combining performance on cancer and noncancer recall rates, the mean area under the receiver operator curve of confidence scores improved significantly by 10% with QT (p-value = 0.01).

CONCLUSION

This MRMC study indicates that QT improves non-cancer recall rates without substantially affecting cancer recall rates. The main limitation is the small number of cases from retrospective data. A larger prospective MRMC study is warranted for further assessment.

Accuracy of Cyst Versus Solid Diagnosis in the Breast Using Quantitative Transmission (QT) Ultrasound

Rational and Objectives

This study aims to evaluate the diagnostic utility of breast imaging using transmission ultrasound. We present readers’ accuracy in determining whether a breast lesion is a cyst versus a solid using transmission ultrasound as an adjunct to mammography.

Materials and Methods

This retrospective multi-reader, multi-case receiver operating characteristic study included 37 lesions seen on mammography and transmission ultrasound. Cyst cases were confirmed as cysts using their appearance on handheld ultrasound. Solid cases were confirmed as solids with pathology results. Fourteen readers performed blinded, randomized reads with mammog-raphy + quantitative transmission scan images, assigning both a confidence score (0–100) and a binary classification of cyst or solid. A 95% percentile bootstrap confidence interval (CI) was computed for the readers’ mean receiver operating characteristic area, sensitivity, and specificity.

Results

Using the readers’ binary classification of cyst or solid lesions, the mean sensitivity and specificity were 0.933 [95% CI: 0.837, 0.995] and 0.858 [95% CI: 0.701, 0.985], respectively. When the readers’ confidence scores were used to distinguish a cyst versus solid, the mean receiver operating characteristic area was 0.920 [95% CI: 0.827, 0.985].

Conclusions

Transmission ultrasound can provide an accurate assessment of a cyst versus a solid lesion in the breast. Prospective clinical trials will further delineate the role of transmission ultrasound as an adjunct to mammography to increase specificity in breast evaluation.

3-D Nonlinear Acoustic Inverse Scattering: Algorithm and Quantitative Results

We describe a novel 3-D ultrasound technology, the quantitative transmission ultrasound system and algorithm to image a pendent breast in a water bath. Quantitative accuracy is verified using phantoms. Morphological accuracy is verified using cadaveric breast and in vivo images, and spatial resolution is estimated. This paper generalizes an earlier 2-D algorithm to a full 3-D inversion algorithm and shows the importance of such a 3-D algorithm for artifact suppression as compared with the 2-D algorithm. The resultant high-resolution ultrasound images, along with quantitative information regarding tissue speed of sound/stiffness, provide a more accurate depiction of the breast anatomy and lesions, contributing to improved breast care.

Imaging approaches to diagnosis and management of common ductal abnormalities

Ductal disease is an important, often overlooked, and poorly understood issue in breast imaging that results in delays in diagnosis and patient care. The differential diagnosis for an intraductal mass is broad and includes inspissated secretions, infection, hemorrhage, solitary or multiple papillomas, and malignancy. Each breast is composed of eight or more ductal systems, with most disease arising in the terminal ductal-lobular unit. Imaging evaluation of the ductal system usually entails a combination of mammography, galactography, ultrasonography (US), and in some cases magnetic resonance (MR) imaging. The most common finding with all modalities is ductal dilatation with a focal or diffuse abnormality. Benign diseases of the ducts include duct ectasia, blocked ducts, inflammatory infiltrates, periductal mastitis, apocrine metaplasia, intraductal papillomas, and papillomatosis. Malignant diseases of the ducts include ductal carcinoma in situ, invasive ductal carcinoma, and Paget disease. Most commonly performed with US or MR imaging guidance, percutaneous biopsy methods are helpful in diagnosis and management of ductal findings. Because most findings are smaller than 1 cm, located within a duct, and thus sometimes not visible after a single pass, vacuum-assisted devices help improve the accuracy of sampling.

Avoiding pitfalls in mammographic interpretation

There is a public misconception that screening mammography detects all breast malignancies. The objective of this pictorial essay is to review classic mammographic features of malignancy that, if missed, could potentially result in malpractice litigation. By identifying radiologic themes, we attempt to improve awareness about the imaging characteristics of a variety of subtle malignancies.

Sonographic Hematoma-Guided vs Wire-Localized Lumpectomy for Breast Cancer

HYPOTHESIS

Sonographic hematoma-guided (SHG) lumpectomy achieves better margin clearance with a smaller volume of resection compared with wire-localized (WL) lumpectomy.

DESIGN

Retrospective study.

SETTING

University Comprehensive Breast Center.

PATIENTS

Consecutive patients treated over 6 months at the breast center with stereotactic biopsy-proven cancers that were not visualized on ultrasonography. The SHG and WL techniques were compared.

MAIN OUTCOME MEASURES

The matching variables were age, mammographic abnormality, tumor size and type, and lymph node status. The outcome variables were the closest margin of resection, volume of resection, resection index (resection volume divided by tumor volume), and rate of margin revision.

RESULTS

Twenty-nine patients had SHG lumpectomy and 34 had WL lumpectomy. The SHG and WL groups were similar in age, mammographic abnormality, tumor size and type, and lymph node status. The median (interquartile range) closest margin was 5.0 (5-8) mm in the SHG group vs 3.5 (1-7) mm in the WL group (P = .01). The median (interquartile range) resection volume was 85.0 (60-128) cm(3) in the SHG group vs 143.4 (54-229) cm(3) in the WL group (P = .048). The median (interquartile range) resection index was 77.1 (51-220) in the SHG group vs 315.9 (89-3025) in the WL group (P = .003). The margin was revised in 1 (3.4%) of the patients who underwent SHG lumpectomy vs 5 (14.7%) of the patients who underwent WL lumpectomy (P = .20).

CONCLUSIONS

Sonographic hematoma-guided lumpectomy is superior to WL lumpectomy in obtaining adequate margins while minimizing the volume of resection.

Post-therapy iodine-131 localization in unsuspected large renal cyst: possible mechanisms

Sensitive and specific, whole-body 131I scintigraphy remains an important technique for diagnosing metastases from differentiated papillary or follicular thyroid carcinoma. False-positive 131I localization is well recognized and can occur in a variety of conditions. We present a case of intense 131I localization in a previously unsuspected large renal cyst; the lesion was not visualized on routine preablation diagnostic 131I scintigraphy but was obvious on post-therapeutic whole-body imaging, underscoring the value of post-therapy imaging in detecting abnormalities not apparent on diagnostic studies. Radioiodine within the urinary bladder or, at times, the renal collecting system is expected, because 131I excretion is primarily by glomerular filtration. In the case presented here, 131I activity within the renal cyst supports the concept that iodide is subject to an active secretory process by the renal tubule.