B. Boné

Dynamic MR imaging of the breast. Analysis of kinetic and morphologic diagnostic criteria.

Purpose: To assess the value of kinetic and architectural diagnostic criteria on dynamic MR breast imaging, and to construct a scoring system for lesion characterization. Material and Methods: A total of 92 women with 109 histopathologically verified breast lesions were included in this retrospective study. The patients were examined by a 1.5 T system using a dedicated double breast coil. A dynamic examination with one precontrast and seven postcontrast series was performed, using a T1-weighted 3D FLASH sequence. Thirty lesions (15 malignant and 15 benign) were randomly chosen for the validation set, and the remaining 79 lesions (62 malignant and 17 benign) formed the estimation set, in which multivariate analysis was performed in order to select the most important features. These parameters were then used for constructing the scoring system, which was tested on the validation set. The scoring system was compared with the routine standard evaluation that used all established diagnostic criteria. ROC curves were generated to assess the diagnostic accuracy of different approaches. Results: In the multivariate analysis of the 79 lesions, time-to-peak enhancement and the descriptor of margins were found to be the most important independent factors for distinguishing benign from malignant lesions, and formed the basis of the scoring system. The areas under the ROC curves for the standard evaluation, and the scoring system were 0.813 and 0.880 in the 30 lesions. Conclusion: Time-to-peak enhancement and the descriptor of margins appear to be the most important diagnostic criteria for mass lesions in dynamic breast MR imaging.

Sensitivity and specificity of MR mammography with histopathological correlation in 250 breasts.

Purpose: The aim of our prospective study was to determine the diagnostic accuracy of MR mammography (MRM) in detecting malignant disease. Material and Methods: In 231 consecutive patients scheduled for surgery because of mammographic or palpable lesions suspected of malignancy, the breasts were examined with T1-weighted transversal images using a 3-D fast low angle shot (FLASH) sequence. One pre- and 2 post-contrast images were obtained. Histological examination of the surgical specimens showed carcinoma in 155 breasts, of which 138 were invasive and 17 in situ. Results: MRM detected 144 of the 155 malignancies and was false-negative in 11 cases. Eight of these MRM-missed tumours were invasive and 3 were in situ cancers. Benign lesions were found at microscopy in 95 breasts, of which MRM correctly diagnosed 69. The cellular composition of the 26 false-positive lesions (myxomatous stromal change, high vascularity, and epithelial or apocrine hyperplasia) might explain the false positivity. The sensitivity and specificity of MRM were 93% and 73%, respectively. Conclusion: MRM should be interpreted with caution, and supplemented with e.g. mammography and ultrasonography.

Diagnostic Accuracy of Mammography and Contrast-Enhanced MR Imaging in 238 Histologically Verified Breast Lesions

Purpose: To determine the sensitivity and specificity of X-ray mammography and of MR imaging in 238 consecutively operated breasts, and to correlate the findings to histopathological diagnosis. Material and Methods: Over 15 months, 220 patients scheduled for breast surgery were examined consecutively, before surgery, by means of both mammography and MR imaging. of the 220 patients, 18 underwent bilateral breast surgery. The entire breast was examined by means of T1-weighted transversal images using a 3D fast low-angle shot (FLASH) sequence. One pre— and 2 post-contrast scans were performed. Each breast was examined by means of mammography and 3 views were applied as routine. All palpable and mammographically suspect lesions were examined on additional images as microfocus magnification or spot compression. The two methods were evaluated independently of each other. Results: In total, 145 malignant and 93 benign lesions were found at histopathological examination. The sensitivity of mammography was 89% and MR imaging 92%. The specificity was 72% in both methods. When the results of the 2 methods were combined, a sensitivity of 99% and a specificity of 55% was achieved. Conclusion: Mammography and MR imaging seemed to complement each other to produce a high sensitivity. Unfortunately it is impossible at present to supplement mammography with MR imaging in each patient as a routine owing to the current technical and financial limitations.

Imaging breasts with silicone implants

Abstract. Over the last two decades, the use of breast implants both for breast augmentation and for breast reconstruction following mastectomy has increased substantially. It is estimated that around two million women have undergone breast augmentation, while hundreds of thousands have had breast reconstruction surgery. Different types of material have been used for breast implants, but silicone gel implants have been the dominating implant type. Many implants can lead to complications, such as hardening and rupture, and may therefore need in vivo evaluation by imaging, particularly if they lead to clinical symptoms. They can also pose problems in the assessment of surrounding breast tissue by conventional mammography. In this respect, imaging modalities such as ultrasound, computed tomography and magnetic resonance imaging offer greater possibilities to assess a failing implant, as well as surrounding breast tissue. Several factors, mainly of a psychological nature, lead to requests for breast implants. In this review article, only the imaging aspects of breasts with silicone gel implants will be dealt with. Each modality is concisely presented with its possibilities and limitations.

Contrast-enhanced MR imaging as a prognostic indicator of breast cancer

Background: Using contrast-enhanced MR imaging in the diagnosis of breast cancer may provide additional information not only on tumor extension but also on the biological behavior of tumors. Thus certain characteristics such as tumor angiogenesis and the proliferating activity of the tumor, which have been shown to correlate significantly with prognosis, are both potentially amenable to analysis by MR imaging Material and Methods: We compared contrast enhancement in 50 malignant breast tumors at MR imaging to several prognostic factors, such as tumor size, lymph-node status, histological grade of malignancy, tumor angiogenesis, and proliferating activity as shown by the mitotic count and PCNA immunoreactivity Results: There was significant correlation between contrast enhancement at MR imaging of breast cancer and both tumor angiogenesis and proliferative cellular activity as shown by PCNA immunoreactivity. Furthermore, there was a correlation between contrast enhancement and tumor malignancy grade as well as tumor invasiveness Conclusion: These observations suggest that contrast enhancement at MR imaging may be influenced by factors that have prognostic value. If this assumption is correct, contrast-enhanced MR imaging may become a valuable prognostic tool in the pre-operative evaluation of breast cancers

Comparison of lesion size estimated by dynamic MR imaging, mammography and histopathology in breast neoplasms

Abstract. To evaluate the accordance of size measurements of malignant breast lesions 65 women with 76 malignant lesions were preoperatively examined with triple diagnosis (mammography was performed in three views with additional views if necessary) and dynamic MR imaging using a subtraction technique with a 3D T1-weighted sequence. Maximum lesion size at histopathology was used as gold standard and compared with maximum lesion size at MRI and mammography. All measurements were made independently for each method. Histopathology verified 48 invasive, 5 in situ, and 23 mixed lesions. No significant difference was found for the pure invasive lesions (p=0.366). In the mixed lesions a slightly better result for MRI was indicated (p=0.116), although there was a great spread. Only five pure in situ lesions were assessed, too few to draw any statistical conclusions (p>0.5). An overall difference indicated a slight superiority of MRI (p=0.097). The MR imaging and mammography are both good at measuring the size of detected invasive breast malignancies. The total sizes of mixed lesions are frequently underestimated by both MRI and mammography, although the invasive parts were equally well described and measured with both methods.

Contrast-Enhanced MR Imaging of the Breast in Patients with Breast Implants After Cancer Surgery

The purpose of the study was to determine the value of contrast-enhanced MR imaging in the assessment of local recurrence in breast cancer patients who underwent mastectomy and breast reconstruction with an implant. Eighty-three patients have been evaluated by semidynamic contrast-enhanced MR imaging. The T1-weighted FLASH 3-D sequence was repeated twice postcontrast for evaluation of the entire breast bilaterally. The findings were compared to physical examination, mammography and histopathology. Recurrence verified by histopathology occurred in 14 of 83 patients (17%). Contrast-enhanced MR imaging was superior to palpation and mammography in revealing recurrences, especially when these were located close to the chest wall. MR was also more sensitive in detecting multiple foci of cancers. Our study revealed that MR imaging was influenced by size, type and composition of the tumor, as illustrated by the false-negative results. Therefore, the use of all 3 investigation methods is necessary for detecting recurrence at an early stage during the postoperative follow-up.

Sensitivity and Specificity of Planar Scintimammography with 99mTc-Sestamibi

Purpose: The aim of our prospective study was to determine the diagnostic accuracy of planar breast imaging with 99mTc-MIBI in detecting malignant disease. Material and Methods: Ninety-six consecutive patients with 121 clinically-and/or mammographically-detected breast lesions underwent preoperative planar scintimammography. Ten minutes after injection of 700 MBq 99mTc-MIBI, two lateral prone and one anterior supine projections with an acquisition time of 8 minutes each were obtained. Interpretation of scintimammographic results was made blindly and any focal accumulation of MIBI in the breasts was the criterion for an abnormal scintigram. All lesions were operated on and histologically verified. Results: Histologically, 86 malignant and 35 benign lesions were found in 121 breast lesions. A sensitivity of 83.7% and a specificity of 74.2% for malignancy was achieved at planar scintimammography. Conclusion: Scintimammography with 99mTc-MIBI is an imaging modality of modest usefulness in the investigation of breast lesions. The method has a low sensitivity in lesions smaller than 10 mm in diameter, which decreases the clinical use of the method.

Mechanism of contrast enhancement in breast lesions at MR imaging

Purpose: the aim of the study was to explain why breast lesions are enhanced by contrast medium at MR imaging and to elucidate the histopathological basis for the overlap in the enhancement patterns of benign and malignant breast lesions Material and Methods: Ten invasive breast carcinomas and 10 benign breast lesions were selected for the study. of the 10 carcinomas, 5 showed a strong and early contrast enhancement, and 5 did not. of the 10 benign lesions, 5 showed a strong and early contrast enhancement, and 5 showed no enhancement. the following morphometric variables were evaluated: proliferation cell index of neoplastic parenchymal cells, S-phase fraction, nuclear ploidy analysed by image DNA-cytometry, microvessel density, and the percentage proportion of the interstitial area Results: Contrast enhancement was related to the proliferating activity of the hyperplastic or neoplastic parenchymal cells and was inversely correlated with the interstitial area in carcinomas as well as in benign tumours and non-neo-plastic lesions of the breast Conclusion: Morphometric variables play an important role in the general mechanism of MR contrast enhancement in examinations of the breast and explain the histopathological basis for the overlap in the enhancement patterns of benign and malignant breast lesions

The role of scintimammography with 99mtc-sestamibi as a complementary diagnostic technique in the detection of breast cancer

Purpose: To prospectively determine the clinical value of scintimammography (Sc) with 99mTc-sestamibi as a complementary method to triple diagnosis (TD) in detecting malignant disease of the breast. Material and Methods: Ninety-six patients with 119 clinically or mammographically detected breast lesions underwent TD procedures, including clinical examination, mammography and fine-needle aspiration cytology. Prone planar Sc with 99mTc-sestamibi was performed in all 96 patients. Five groups were defined for diagnosis: 1 = normal; 2 = benign; 3 = probably benign; 4 = highly suspect of malignancy; and 5 = malignant. All lesions were histopathologically examined. The results of each method per se and the combination of TD with Sc (TD + Sc) were analyzed. Results: Histopathology of the 119 surgically excised breast lesions found 83 malignant and 36 benign lesions. TD missed 6 of 83 carcinomas, resulting in a sensitivity of 92.7%. Sc alone showed sensitivity of 85.5%. The combination TD + Sc missed 1 of 83 carcinomas, and thus had a sensitivity of 98.7%. In mammographically dense breasts both TD and Sc detected 16 of 18 carcinomas, while the combination TD + Sc led to detection of all 18 carcinomas. Conclusion: Adding Sc to TD increases the sensitivity for detection of breast carcinomas. Sc with 99mTc-sestamibi is recommended as a complimentary method to TD in selected cases such as mammographically dense breasts.