Improved accuracy in differentiating malignant from benign mammographic abnormalities: a simple, improved magnetic resonance imaging method

Additional Workups Recommended During Preoperative Breast MRI: Methods to Gain Efficiency and Limit Confusion

BACKGROUND

Preoperative breast MRI is indicated for staging but can lead to complex imaging workups. This study reviewed imaging recommendations made on preoperative MRI exams, to simplify management approaches for patients with newly diagnosed breast cancer.

METHODS

This retrospective single-institution review was restricted to women with breast cancer who underwent staging MRI. Additional breast lesions, separate from index tumors, recommended for additional workup or surveillance were assessed to see which were detected and which characteristics predicted success in detection. Univariate mixed-effects logistic modeling predicted the likelihood of finding lesions using MRI-directed ultrasound (US), with odds ratios reported. Tests were two-sided, with a p value lower than 0.05 considered significant.

RESULTS

In this study, 534 (39.6%) patients had recommendations for additional workup after preoperative MRI. MRI detected additional malignancy in 178 patients (33.3%). Half of the 66 patients who refused an additional workup and opted for mastectomy had additional malignancies at mastectomy. MRI-directed US was 14 times more likely to detect masses than nonmass enhancement (NME) (p < 0.001). NME was detected on US in only 16% of cases, with one third of subsequent biopsy results considered discordant. Probably benign assessments were given to 35 patients, with 23% not returning for follow-up evaluation and 7% returning at least 6 months later than recommended.

CONCLUSION

Use of preoperative breast MRI has increased. Although it can add value, institutions should establish indications and expectations to prevent unnecessary workups. Limiting MRI-directed US to masses, avoiding probably benign assessments, and consulting with patients after MRI but prior to workups can prevent unnecessary exams and confusion.

Recalibrating the decision for MRI-directed breast ultrasound in patients with newly diagnosed breast cancer, factors predicting sonographic success

OBJECTIVE

Evaluate utilization of MRI-directed breast ultrasound (US) in patients with newly diagnosed breast cancer and refine practices to increase success of sonographic lesion detection.

METHODS

This retrospective single-institution review was restricted to women with breast cancer who underwent MRI from November 2006 to January 2017. Enhancing breast lesions, separate from the index tumor, recommended for MRI-directed US were assessed to see which were detected and which characteristics predicted success in detection. Univariate mixed-effects logistic modeling predicted likelihood of finding breast lesions with US, with odds ratios reported. All tests were two-sided with p < 0.05 considered significant.

RESULTS

A total of 275 patients underwent MRI-directed US for 361 breast lesions, of which 187 (51.8%) were found on US. Of those detected, 171 (91.4%) were masses and 16 (8.6%) were nonmass enhancement (NME), with masses 14 times more likely to be seen (p < 0.001). Size alone was not a significant predictor but achieved significance when associated with lesion type (mass size, p < 0.001). Masses with irregular shapes or margins and invasive carcinomas were more frequently detected. Patient age, internal enhancement pattern, and distribution of NME were not significant predictors in sonographic detection. A presumed sonographic correlate for NME was found for 16 (16.2%) of 99 attempted lesions.

CONCLUSION

As MRI access expands, utilization of MRI-directed US should be scrutinized to avoid downstream practice inefficiencies. Sonographic detection rates for NME remain low for women undergoing MRI for disease extent, with NME often better suited for MRI-guided biopsy.

Follow-up design of unexpected enhancing lesions on preoperative MRI of breast cancer patients

PURPOSE

We aimed to analyze the characteristics and long-term follow-up results of unexpected enhancing lesions on preoperative magnetic resonance imaging (MRI) of breast cancer patients.

METHODS

From August 2007 through February 2010, second-look ultrasound (SLUS) was recommended for 84 of 312 breast cancer patients having unexpected enhancing lesions on MRI. SLUS was performed for 85 unexpected enhancing lesions in 72 patients. We performed a retrospective review to determine the size, lesion type, enhancement kinetic curve, and location in relation to the index cancer. We obtained the pathologic outcome of the detected lesions and in case of a negative finding on SLUS, we performed follow-up examinations for at least two years.

RESULTS

Of 85 unexpected lesions, 72 (85%) were detected on SLUS. In total, 41 lesions (56.9%) were confirmed as malignant and 31 lesions (43.6%) as benign. Cancer rate was statistically higher in lesions having type III enhancement pattern, located at the same quadrant as the index cancer. However, no significant association was observed between the cancer rate and the lesion size and type. None of the 13 negative cases on SLUS developed cancer on follow-up.

CONCLUSION

In case of unexpected enhancing lesions on preoperative MRI of breast cancer patients, SLUS can be useful to find out the matched lesion. Lesions with type III enhancement pattern or those located at the same quadrant as the index cancer should be considered as a separate cancer. In the absence of any suspicious findings on SLUS, patient may be followed up with confidence.

Contralateral enhancing lesions on magnetic resonance imaging in patients with breast cancer: role of second-look sonography and imaging findings of synchronous contralateral cancer

OBJECTIVES

The purposes of this study were to assess the clinical utility of sonography for evaluation of contralateral suspicious lesions detected on magnetic resonance imaging (MRI) in patients with breast cancer and to compare imaging findings of the index and synchronous contralateral cancers.

METHODS

We performed breast MRI on 853 consecutive patients with histologically confirmed breast cancer between January 2006 and December 2009. All patients underwent mammography and whole-breast sonography before MRI. We included 126 contralateral enhancing lesions in 98 patients who underwent second-look sonography. Lesions with sonographic correlation were biopsied using sonographic guidance, and lesions without sonographic correlation were biopsied using computed tomographic guidance or followed with imaging modalities.

RESULTS

Of 126 suspicious lesions, 81 (64%) were correlated on sonography, and 45 (36%) were not. Of 81 correlated lesions, 16 (20%) were malignant, and 65 (80%) were benign. Of 45 lesions that were not correlated on sonography, only 1 (2%) was malignant. Of 17 contralateral cancers, 11 were detected on initial sonography and 5 on second-look sonography. The index and contralateral cancers showed statistically significant differences in the sonographic boundary (P = .003) and posterior echogenicity (P = .013). The contralateral cancers detected on initial or second-look sonography showed significant differences in the echo pattern (P = .001).

CONCLUSIONS

Magnetic resonance imaging is a reliable tool for detection of occult contralateral breast cancer. With second-look sonography, we can find additional contralateral cancer. When enhancing lesions on MRI are not correlated on sonography, MRI- or computed tomography-guided biopsy or short-term imaging follow-up should be done.

MR-directed ("Second-Look") ultrasound examination for breast lesions detected initially on MRI: MR and sonographic findings

OBJECTIVE

The objective of our study was to assess the clinical utility of MR-directed ("second-look") ultrasound examination to search for breast lesions detected initially on MRI.

MATERIALS AND METHODS

A retrospective review was performed of the records of 158 consecutive patients (202 lesions) with breast abnormalities initially detected on MRI between July 2003 and May 2006. All lesions were detected as enhancing findings on a dynamic contrast MR study and were subsequently evaluated with ultrasound. Ultrasound was performed using MR images as a guide to lesion location, size, and morphology. Pathology findings were confirmed by subsequent percutaneous biopsy or lesion excision. Imaging follow-up was used for probably benign lesions, which were not biopsied.

RESULTS

Of the 202 MRI-detected lesions, ultrasound correlation was made in 115 (57%) including 33 malignant lesions and 82 benign lesions. The remaining 87 lesions were not sonographically correlated and included 11 malignant lesions and 76 nonmalignant lesions. Mass lesions identified on MRI were more likely to have a sonographic correlate than nonmasslike lesions (65% vs 12%, respectively); malignant mass lesions were more likely to show an ultrasound correlation (85%). The malignant lesions with successful sonographic correlation tended to present with subtle sonographic findings.

CONCLUSION

MR-directed ultrasound of MRI-detected lesions was useful for decision making as part of the diagnostic workup. Malignant lesions were likely to have an ultrasound correlate, especially when they presented as masses on MRI. However, the sonographic findings of these lesions were often subtle, and careful scanning technique was needed for successful MRI-ultrasound correlation.

Color-coded automated signal intensity curves for detection and characterization of breast lesions: preliminary evaluation of a new software package for integrated magnetic resonance-based breast imaging

OBJECTIVES

The objective of this study was to evaluate the value of a color-coded automated signal intensity curve software package for contrast-enhanced magnetic resonance mammography (CE-MRM) in patients with suspected breast cancer.

MATERIALS AND METHODS

Thirty-six women with suspected breast cancer based on mammographic and sonographic examinations were preoperatively evaluated on CE-MRM. CE-MRM was performed on a 1.5-T magnet using a 2D Flash dynamic T1-weighted sequence. A dosage of 0.1 mmol/kg of Gd-BOPTA was administered at a flow rate of 2 mL/s followed by 10 mL of saline. Images were analyzed with the new software package and separately with a standard display method. Statistical comparison was performed of the confidence for lesion detection and characterization with the 2 methods and of the diagnostic accuracy for characterization compared with histopathologic findings.

RESULTS

At pathology, 54 malignant lesions and 14 benign lesions were evaluated. All 68 (100%) lesions were detected with both methods and good correlation with histopathologic specimens was obtained. Confidence for both detection and characterization was significantly (P < or = 0.025) better with the color-coded method, although no difference (P > 0.05) between the methods was noted in terms of the sensitivity, specificity, and overall accuracy for lesion characterization. Excellent agreement between the 2 methods was noted for both the determination of lesion size (kappa = 0.77) and determination of SI/T curves (kappa = 0.85).

CONCLUSIONS

The novel color-coded signal intensity curve software allows lesions to be visualized as false color maps that correspond to conventional signal intensity time curves. Detection and characterization of breast lesions with this method is quick and easily interpretable.

Breast Lesion Detection and Characterization at Contrast-enhanced MR Mammography: Gadobenate Dimeglumine versus Gadopentetate Dimeglumine

PURPOSE

To prospectively and intraindividually compare equivalent (0.1 mmol per kilogram of body weight) doses of gadobenate dimeglumine and gadopentetate dimeglumine for accuracy of detection and characterization of breast lesions at contrast material-enhanced magnetic resonance (MR) mammography.

MATERIALS AND METHODS

Ethics committee approval and informed consent were obtained. Twenty-six consecutive women (mean age, 47.8 years) suspected of having a breast tumor at mammography and sonography underwent two identical MR examinations at 1.5 T; examinations were separated by more than 48 hours but less than 72 hours. A T1-weighted three-dimensional gradient-echo sequence was used, and images were acquired before and at 0, 2, 4, 6, and 8 minutes after randomized injection of gadopentetate dimeglumine or gadobenate dimeglumine at an identical flow rate of 2 mL/sec. Separate and combined assessment of unenhanced, contrast-enhanced, and subtracted images was performed blindly by two readers in consensus. Accuracy for lesion detection was determined against a final diagnosis based on findings at conventional mammography, sonography, and surgery. Sensitivity, specificity, positive and negative predictive values, and overall accuracy for malignant lesion identification were determined against histologic results. Data were analyzed with the McNemar test, proportional odds models, and analysis of variance.

RESULTS

MR mammography with gadobenate dimeglumine depicted significantly (P = .003) more lesions (45 of 46) than did that with gadopentetate dimeglumine (36 of 46), and detected lesions were significantly (P < .001) more conspicuous with gadobenate dimeglumine. Confidence for characterization was significantly (P = .031) greater with gadobenate dimeglumine. Comparison of the contrast agents for their ability to help identify malignant lesions revealed significant (P = .02) superiority for gadobenate dimeglumine: Sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy for malignant lesion identification were, respectively, 94.7%, 100%, 100%, 80.0%, and 95.6% with gadobenate dimeglumine and 76.3%, 100%, 100%, 47.1%, and 80.4% with gadopentetate dimeglumine. Quantitative evaluation of signal intensity-time curves revealed significantly (P < .001) greater lesion enhancement with gadobenate dimeglumine.

CONCLUSION

Detection of breast lesions and accurate identification of malignant lesions at MR imaging are significantly superior with gadobenate dimeglumine in comparison with gadopentetate dimeglumine.

A case of fat necrosis after breast quadrantectomy in which preoperative diagnosis was enabled by MRI with fat suppression technique

A 63-year-old woman was found to have a left breast mass after quadrantectomy and radiation for bilateral breast cancer on postoperative cyclic examination. Intramammary recurrence could not be excluded by physical examination, mammography, or ultrasound examination. MR imaging with fat suppression technique revealed an oil-containing lesion, indicating fat necrosis. It was confirmed histologically that the mass-forming lesion included no cancer tissue. MR imaging with fat suppression technique appears to be a promising method for identification of postoperative mass lesions of the breast.

Magnetic Resonance Imaging in Comparison to Clinical Palpation in Assessing the Response of Breast Cancer to Epirubicin Primary Chemotherapy

PURPOSE

To investigate whether magnetic resonance imaging (MRI) is superior to clinical palpation in the assessment of response of breast cancer to primary chemotherapy (PC).

PATIENTS AND METHODS

Seventy-three patients with T2-4, N0, M0 breast cancer were treated with 3-4 cycles of single agent epirubicin before definitive surgery. MRI was performed at baseline condition and at the end of chemotherapy.

RESULTS

According to the WHO criteria, 20 (27.4%) patients attained a complete response (CR) by clinical palpation and 41 (56.2%) a partial response. The corresponding response rate by MRI was 11 (15.1%) and 34 (46.6%), respectively. Residual tumor assessed by MRI better correlated with pathologic measurements (Spearman r : 0.72) than residual tumor assessed by clinical palpation (Spearman r : 0.58). Post-chemotherapy histology evaluation revealed pathologic CR in three cases, only one of them was considered as complete responder by MRI. Residual disease consisted in in situ carcinoma in four cases, one of them was complete responder at MRI, the remaining three showed residual abnormal contrast enhancement indistinguishable from that of invasive tumors.

CONCLUSIONS

As compared to pathology specimens, MRI is able to represent the extent of cancer more accurately than clinical palpation. It constitutes a promising technique in assessing the BC response to PC. The current limit of MRI is the scarce specificity in predicting the nature of residual disease.

Gadobenate dimeglumine-enhanced MRI of the breast: analysis of dose response and comparison with gadopentetate dimeglumine

OBJECTIVE

The purpose of this study was to evaluate the clinical efficacy and dose response relationship of three doses of gadobenate dimeglumine for MRI of the breast and to compare the results with those obtained after a dose of 0.1 mmol/kg of body weight of gadopentetate dimeglumine. SUBJECTS AND METHODS. Gadobenate dimeglumine at 0.05, 0.1, or 0.2 mmol/kg of body weight or gadopentetate dimeglumine at 0.1 mmol/kg of body weight was administered by IV bolus injection to 189 patients with known or suspected breast cancer. Coronal three-dimensional T1-weighted gradient-echo images were acquired before and at 0, 2, 4, 6, and 8 min after the administration of the dose. Images were evaluated for lesion presence, location, size, morphology, enhancement pattern, conspicuity, and type. Lesion signal intensity-time curves were acquired, and lesion matching with on-site final diagnosis was performed. A determination of global lesion detection from unenhanced to contrast-enhanced and combined images was performed, and evaluations were made of the diagnostic accuracy for lesion detection and characterization. A full safety evaluation was conducted.

RESULTS

Significant dose-related increases in global lesion detection were noted for patients who received gadobenate dimeglumine (p < 0.04, all evaluations). The sensitivity for detection was comparable for 0.1 and 0.2 mmol/kg of gadobenate dimeglumine, and specificity was highest with the 0.1 mmol/kg dose. Higher detection scores and higher sensitivity values for lesion characterization were found for 0.1 mmol/kg of gadobenate dimeglumine compared with 0.1 mmol/kg of gadopentetate dimeglumine, although more variable specificity values were obtained. No differences in safety were observed, and no serious adverse events were reported.

CONCLUSION

Gadobenate dimeglumine is a capable diagnostic agent for MRI of the breast. Although preliminary, our results suggest that 0.1 mmol/kg of gadobenate dimeglumine may offer advantages over doses of 0.05 and 0.2 mmol/kg of gadobenate dimeglumine and 0.1 mmol/kg of gadopentetate dimeglumine for breast lesion detection and characterization.

Independent component analysis for the examination of dynamic contrast-enhanced breast magnetic resonance imaging data: preliminary study

RATIONALE AND OBJECTIVE

An application of independent component analysis (ICA) is reported for the detection and characterization of breast lesions in dynamic contrast-enhanced MRI. The ICA technique, which uses a novel statistical algorithm to separate mixed signal sources of unknown nature, enables the extraction of spatial and temporal features of dynamic MRI data.

MATERIALS AND METHODS

Six patients with confirmed lesion diagnosis (three with malignancy and three with benign condition) participated in this study. T1-weighted MRI covering both breast volumes was dynamically acquired in every 90 seconds after the bolus injection of contrast media using three-dimensional fast low-angle shot sequence (3-D FLASH).

RESULTS

With the application of the ICA, differential signal responses were delineated from benign and malignant lesions, and areas with high temporal correlations with the extracted signal components were selectively visualized.

CONCLUSIONS

The results suggest that ICA allowed for an identification of lesion morphology and lesion-specific dynamic enhancement patterns.