Jennifer B. Kaplan

MRI Follow-Up After Concordant, Histologically Benign Diagnosis of Breast Lesions Sampled by MRI-Guided Biopsy

OBJECTIVE Follow-up MRI can be useful to confirm a benign diagnosis after MRI-guided breast biopsy. This retrospective study was undertaken to evaluate appropriate timing and imaging interpretation for the initial follow-up MRI when a benign, concordant histology is obtained using MRI-guided breast biopsy. MATERIALS AND METHODS Retrospective review was performed of 177 lesions visualized only by MRI in 172 women who underwent 9-gauge, vacuum-assisted core biopsy and marker placement with imaging-concordant benign histology. All underwent follow-up MRI within 12 months. Timing of the follow-up study, change in size, results of second biopsy if performed, and distance of localizing marker to the lesion on the follow-up study were recorded. RESULTS At initial follow-up, 155 lesions were decreased or gone, 14 lesions were stable, and eight were enlarged. Seventeen (9.6%, 17/177) lesions underwent a second biopsy, including six enlarging, 10 stable, and one decreasing. Of these, four were malignant. Enlargement was seen in two carcinomas at 6 and 12 months. Two carcinomas, one stable at 2 months and another stable at 3 and 11 months, were rebiopsied because of suspicion of a missed lesion in the former and worrisome mammographic and sonographic changes in the latter. The distance of the marker from the lesion on follow-up did not correlate with biopsy accuracy. CONCLUSION Follow-up MRI did not detect missed cancers because of lesion enlargement before 6 months after biopsy; two of four missed cancers were stable. The localizing marker can deploy away from the target despite successful sampling.

Imaging–Histologic Discordance at MRI-Guided 9-Gauge Vacuum-Assisted Breast Biopsy

OBJECTIVE The purpose of this study was to determine the frequency of discordance at MRI-guided vacuum-assisted biopsy and to assess the cancer rate in discordant lesions. MATERIALS AND METHODS With institutional review board approval, retrospective review was performed of a database of 342 lesions that had MRI-guided vacuum-assisted biopsy during a 39-month period. Biopsy samples were obtained in a 1.5-T magnet using a 9-gauge MRI-compatible vacuum-assisted biopsy device. Medical and pathology records were reviewed to determine the number of discordant lesions and surgical outcome. Statistical analysis was performed. RESULTS Among 342 lesions that had MRI-guided vacuum-assisted biopsy, results were discordant in 24 (7% [95% CI, 3-14%]) lesions. The discordance rate was significantly (p < 0.001) higher among MRI target lesions that were possibly missed rather than sampled. A trend was seen (p < 0.06) toward a higher discordance rate in MRI lesions that were sampled rather than excised at MRI-guided vacuum-assisted biopsy. Subsequent surgery in 20 discordant lesions yielded cancer in six (30% [12-54%]), including ductal carcinoma in situ (DCIS) in two and invasive carcinoma in four (three ductal and one lobular, all with DCIS). The cancer rate among discordant lesions was significantly higher in postmenopausal women than in premenopausal women (p <0.05). CONCLUSION Imaging-histologic discordance was found in 7% of lesions that had MRI-guided vacuum-assisted biopsy. Among discordant lesions, surgical excision revealed cancer in 30%. Imaging-histologic correlation is essential after MRI-guided vacuum-assisted biopsy to avoid delay in the diagnosis of breast cancer.

Abbreviated protocol for breast MRI: Are multiple sequences needed for cancer detection?

OBJECTIVE To evaluate the ability of an abbreviated breast magnetic resonance imaging (MRI) protocol, consisting of a precontrast T1 weighted (T1W) image and single early post-contrast T1W image, to detect breast carcinoma. MATERIALS AND METHODS A HIPAA compliant Institutional Review Board approved review of 100 consecutive breast MRI examinations in patients with biopsy proven unicentric breast carcinoma. 79% were invasive carcinomas and 21% were ductal carcinoma in situ. Four experienced breast radiologists, blinded to carcinoma location, history and prior examinations, assessed the abbreviated protocol evaluating only the first post-contrast T1W image, post-processed subtracted first post-contrast and subtraction maximum intensity projection images. Detection and localization of tumor were compared to the standard full diagnostic examination consisting of 13 pre-contrast, post-contrast and post-processed sequences. RESULTS All 100 cancers were visualized on initial reading of the abbreviated protocol by at least one reader. The mean sensitivity for each sequence was 96% for the first post-contrast sequence, 96% for the first post-contrast subtraction sequence and 93% for the subtraction MIP sequence. Within each sequence, there was no significant difference between the sensitivities among the 4 readers (p=0.471, p=0.656, p=0.139). Mean interpretation time was 44s (range 11-167s). The abbreviated imaging protocol could be performed in approximately 10-15 min, compared to 30-40 min for the standard protocol. CONCLUSION An abbreviated breast MRI protocol allows detection of breast carcinoma. One pre and post-contrast T1W sequence may be adequate for detecting breast carcinoma. These results support the possibility of refining breast MRI screening protocols.

Intravoxel Incoherent Motion Diffusion-Weighted MRI at 3.0 T Differentiates Malignant Breast Lesions From Benign Lesions and Breast Parenchyma

To study the differentiation of malignant breast lesions from benign lesions and fibroglandular tissue (FGT) using apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM) parameters.

Impact of Tamoxifen on Amount of Fibroglandular Tissue, Background Parenchymal Enhancement, and Cysts on Breast Magnetic Resonance Imaging

Abstract:  The objective of this study was to evaluate the impact of tamoxifen treatment on amount of fibroglandular tissue (FGT), background parenchymal enhancement (BPE), and cysts on breast MRI. Retrospective search identified 96 women with breast cancer who had a breast MRI both before and during adjuvant tamoxifen therapy between 2002 and 2008. After exclusion of all irradiated breasts, 88 women were eligible. Two readers blinded to tamoxifen treatment status independently rated level of BPE, amount of FGT, and cysts using a 4‐point categorical scale: BPE––Minimal, Mild, Moderate, Marked; FGT––Fatty, Scattered, Heterogeneously Dense (HD), Dense; Cysts––Minimal, Mild, Moderate, Marked. A consensus interpretation was reached in cases of disagreement. During tamoxifen, there was a significant shift from higher to lower degree BPE, cysts, and FGT compared with before tamoxifen. BPE, cysts and FGT decreased in 68% (60/88), 38% (33/88), and 40% (35/88) of women during tamoxifen (p < 0.001 for all measures). After the exclusion of all cases with minimal BPE, cysts, or FGT on the pre‐tamoxifen MRI, the percentage of women demonstrating a decrease in these factors increased to 81% (60/74), 77% (33/43), and 41% (35/86), respectively. Exclusion of patients treated with chemotherapy did not substantially change these results. The percentage of women with decreases in FGT and cysts increased with greater duration on tamoxifen, whereas decreases in BPE were detected early in treatment (<90 days) and did not change substantially with longer duration on tamoxifen. A significant association exists between treatment with tamoxifen and decreases in BPE, cysts, and FGT on breast MRI.

Underestimation of DCIS at MRI-Guided Vacuum-Assisted Breast Biopsy

OBJECTIVE The study objective was to assess the rate of underestimation of ductal carcinoma in situ (DCIS) at MRI-guided 9-gauge vacuum-assisted breast biopsy. MATERIALS AND METHODS An institutional review board-approved retrospective review was performed of 373 consecutive lesions that had undergone MRI vacuum-assisted breast biopsy. In 34 lesions with subsequent surgery, vacuum-assisted breast biopsy yielded DCIS without frank microinvasion or invasion. DCIS underestimates were lesions for which vacuum-assisted breast biopsy yielded DCIS without frank microinvasion or invasion at biopsy and surgery yielded invasive cancer. Records and pathology findings were reviewed. RESULTS Among 34 lesions, vacuum-assisted breast biopsy histology was DCIS in 29 and DCIS with possible microinvasion in five. Of 29 lesions yielding DCIS at MRI vacuum-assisted breast biopsy, surgical excision revealed invasive cancer in five (17%; 95% CI, 6-36%). The DCIS underestimation rate was significantly higher in lesions 6 cm or larger versus smaller lesions (60% vs 8%, p = 0.02). MRI lesion type, kinetics, number of specimens, menopausal status, and target sampling versus excision did not significantly affect underestimation. Of five lesions yielding DCIS with possible microinvasion at MRI vacuum-assisted breast biopsy, surgery revealed invasive carcinoma in four (80%; 95% CI, 28-99%). DCIS underestimation was significantly more likely if MRI vacuum-assisted breast biopsy showed possible microinvasion than if it did not (80% vs 17%, p =0.01). CONCLUSION Underestimation occurred in 17% of lesions yielding DCIS and in 80% of lesions yielding DCIS with possible microinvasion at MRI vacuum-assisted breast biopsy. DCIS underestimation was significantly more likely in lesions measuring 6 cm or larger. No other patient or lesion factors significantly affected DCIS underestimation at MRI vacuum-assisted breast biopsy.

Radial Scar at Image-guided Needle Biopsy: Is Excision Necessary?

Optimal management of a lesion yielding radial scar (RS) without epithelial atypia on breast biopsy is controversial. In this single-institution study spanning 17 years, 53 patients with this biopsy diagnosis were evaluated in terms of clinical, radiologic, and pathologic features and outcomes. RSs were categorized as either “incidental” or as the “targeted” lesion according to defined criteria. Of 48 patients who underwent surgical excision after a diagnosis of RS on biopsy, only 1 had an “upgrade” diagnosis of malignancy (2%). No “incidental” RS was associated with the presence of malignancy on surgical excision. Meta-analysis of 20 RS excision studies demonstrated an overall upgrade rate of 10.4%, with a higher rate in patients with a diagnosis of RS with atypia (26%). The upgrade rate for RS without atypia was 7.5% overall. The lower rate of upgrade to malignancy in this study (2%) is likely related to the thorough radiologic-pathologic review undertaken. In the setting of multidisciplinary agreement and careful radiologic-pathologic correlation, it may be appropriate for patients with a biopsy diagnosis of RS without atypia to forego surgical excision in favor of imaging follow-up.

Breast Cancers Detected at Screening MR Imaging and Mammography in Patients at High Risk: Method of Detection Reflects Tumor Histopathologic Results

Purpose To compare the clinical, imaging, and histopathologic features of breast cancers detected at screening magnetic resonance (MR) imaging, screening mammography, and those detected between screening examinations (interval cancers) in women at high risk. Materials and Methods This retrospective institutional review board-approved, HIPAA-compliant review of 7519 women at high risk for breast cancer who underwent screening with MR imaging and mammography between January 2005 and December 2010 was performed to determine the number of screening-detected and interval cancers diagnosed. The need for informed consent was waived. Medical records were reviewed for age, risk factors (family or personal history of breast cancer, BRCA mutation status, history of high-risk lesion or mantle radiation), tumor histopathologic results, and time between diagnosis of interval cancer and most recent screening examination. The χ(2) test and logistic regression methods were used to compare the features of screening MR imaging, screening mammography, and interval cancers. The Wilcoxon signed-rank test was used to calculate P values. Results A total of 18 064 screening MR imaging examinations and 26 866 screening mammographic examinations were performed. Two hundred twenty-two cancers were diagnosed in 219 women, 167 (75%) at MR imaging, 43 (19%) at mammography, and 12 (5%) interval cancers. Median age at diagnosis was 52 years. No risk factors were associated with screening MR imaging, screening mammography, or interval cancer (P > .06). Cancers found at screening MR imaging were more likely to be invasive cancer (118 of 167 [71%]; P < .0001). Of the 43 cancers found at screening mammography, 38 (88%) manifested as calcifications and 28 (65%) were ductal carcinoma in situ. Interval cancers were associated with nodal involvement (P = .005) and the triple-negative subtype (P = .03). Conclusion In women at high risk for breast cancer who underwent screening with mammography and MR imaging, invasive cancers were more likely to be detected at MR imaging, whereas most cancers detected at screening mammography were ductal carcinoma in situ. Interval cancers were found infrequently and were more likely to be node positive and of the triple-negative subtype. (©) RSNA, 2016.

Complete Excision of the MRI Target Lesion at MRI-Guided Vacuum-Assisted Biopsy of Breast Cancer

OBJECTIVE The purpose of our study was to determine the frequency of complete removal of the imaging target at MRI-guided vacuum-assisted biopsy of breast cancer and to assess the residual cancer rate at surgery in these lesions. MATERIALS AND METHODS With the approval of our institutional review board, retrospective review was performed of 416 consecutive lesions that underwent MRI-guided 9-gauge vacuum-assisted biopsy, of which 76 (18%) yielded cancer. Medical and pathology records were reviewed. RESULTS Vacuum-assisted biopsy histology in 76 cancers was ductal carcinoma in situ in 39 (51%) and invasive cancer in 37 (49%). Median MRI lesion size in these 76 cancers was 1.2 cm (range, 0.4-8.0 cm). The median number of samples obtained was 12 (range, 6-24 samples). Among 76 cancers, the MRI target was completely excised in 23 (30% [95% CI, 20-42%]), sampled in 52 (69% [57-79%]), and possibly missed in one (1% [0-7%]). Complete MRI target excision rather than sampling was significantly more likely in lesions < or = 1 cm than in lesions >1 cm (18/34 = 53% vs 5/41 = 12%; p < 0.001). Surgery, performed in 67 of 76 cancers, showed residual cancer in 55 (82% [71-90%]). The residual cancer rate was significantly lower if the MRI target was completely excised rather than sampled (14/22 = 64% vs 40/44 = 91%; p < 0.02). CONCLUSION Complete excision of the MRI target occurred in 30% of breast cancers diagnosed at MRI-guided vacuum-assisted biopsy. Among cancers in which the MRI target was percutaneously excised, surgery yielded residual cancer in 64%. Complete removal of the MRI target does not ensure complete histologic excision of the cancer.

Percutaneous Core Biopsy of Nonpalpable Breast Lesions: Utility and Impact on Cost of Diagnosis

Percutaneous image-guided core breast biopsy is faster, less invasive, less deforming, and less expensive than surgical biopsy for diagnosing nonpalpable breast lesions. Percutaneous biopsy may be performed using different imaging guidance modalities (e.g., stereotaxis or ultrasound) and different tissue acquisition devices (e.g., automated needles or vacuum-assisted biopsy probes). Stereotactic biopsy may be used for all lesion types (masses and calcifications). Stereotactic 14-gauge automated core biopsy spared a surgical procedure in 76-85% of cases, decreasing the cost of diagnosis by 40-56%. Annual national savings from use of stereotactic 14-gauge automated core biopsy rather than surgical biopsy for nonpalpable lesions would exceed 100 million dollars. Stereotactic 11-gauge vacuum-assisted biopsy yields significant improvement in diagnosis of calcifications and may be used in lesions that are not amenable to stereotactic 14-gauge automated core biopsy. Stereotactic 11-gauge vacuum-assisted biopsy spared a surgical procedure in 76% cases, decreasing cost of diagnosis by 20%. Use of stereotactic 11-gauge vacuum-assisted biopsy for calcifications and for nonpalpable masses not amenable to stereotactic 14-gauge automated core biopsy would yield annual national savings exceeding 50 million dollars. Ultrasound-guided biopsy, used primarily for masses, has several advantages including speed, comfort, lack of radiation exposure, and real-time needle visualization. Ultrasound-guided core biopsy spared a surgical procedure in 85% cases, decreasing the cost of diagnosis by 56%. Although both ultrasound-guided core biopsy and stereotactic biopsy are less expensive than surgery, cost savings are greater for ultrasound-guided core biopsy. An annual national savings over