Pascal A. T. Baltzer

False-Positive Findings at Contrast-Enhanced Breast MRI: A BI-RADS Descriptor Study

OBJECTIVE Breast MRI has high sensitivity in breast cancer detection, and the BI-RADS MRI lexicon was a step toward standardized description of lesions. However, false-positive findings occur and lead to unnecessary biopsy. The purpose of this investigation was to identify criteria for false-positive findings in clinical practice. MATERIALS AND METHODS Eligible for investigation were all breast MRI examinations from a consecutive 16-month time period that had histopathologic verification and findings classified as BI-RADS category 4-6 in the initial MRI report. Accordingly, 132 patients with 120 malignant and 31 benign lesions were enrolled. Two blinded observers categorized lesions into mass or nonmass and used BI-RADS to identify descriptor distribution differences between the benign and malignant subgroups. RESULTS The ratio of mass to nonmass lesions differed significantly (p < 0.001) between benign (1.2:1) and malignant (7:1) findings. Seventeen mass and 14 nonmass lesions were false-positive, and 105 mass and 15 nonmass lesions were true-positive. Among mass lesions, it was possible to differentiate malignant and benign lesions on the basis of margin (smooth, irregular, or spiculated) and dynamic enhancement features (p < 0.05). Among nonmass lesions, only stippled enhancement had a significant difference between the subgroups (p < 0.05). Tumor diameter had no influence on the correct diagnosis of nonmass lesions (p = 0.301). Conversely, among mass lesions, false-positive lesions were smaller than true-positive lesions (p = 0.01). CONCLUSION Nonmass lesions were the major cause of false-positive breast MRI findings. BI-RADS descriptors are not sufficient for differentiating benign and malignant nonmass lesions.

Sensitivity and specificity of unenhanced MR mammography (DWI combined with T2-weighted TSE imaging, ueMRM) for the differentiation of mass lesions

ObjectiveThis study was performed to assess the sensitivity and specificity for malignant and benign mass lesions of a diagnostic approach combining DWI with T2-weighted images (unenhanced MR mammography, ueMRM) and compare the results with contrast-enhanced MR mammography (ceMRM).Materials and methodsConsecutive patients undergoing histopathological verification of mass lesions after MR mammography without prior breast interventions (contrast-enhanced T1-weighted, T2-weighted and DWI sequences) were eligible for this retrospective investigation. Two blinded observers first rated ueMRM and then ceMRM according to the BIRADS scale. Lesion size, ADC values and T2-weighted TSE descriptors were assessed.ResultsThis study examined 81 lesions (27 benign, 54 malignant). Sensitivity of ueMRM was 93% (observer 1) and 86% (observer 2), respectively. Sensitivity of ceMRM was 96.5% (observer 1) and 98.3% (observer 2). Specificity was 85.2% (ueMRM) and 92.6% (ceMRM) for both observers. The differences between both methods and observers were not significant (P ≥ 0.09). Lesion size measurements did not differ significantly among all sequences analyzed. Tumor visibility was worse using ueMRM for both benign (P < 0.001) and malignant lesions (P = 0.004).ConclusionSensitivity and specificity of ueMRM in mass lesions equal that of ceMRM. However, a reduced lesion visibility in ueMRM may lead to more false-negative findings.

Magnetic resonance imaging of inflammatory breast carcinoma and acute mastitis. A comparative study

The aim of this study was to evaluate the potential of magnetic resonance mammography (MRM) to distinguish inflammatory breast carcinomas (IBC) from acute mastitis (AM). This study compared MRM examinations of two selected groups of patients: 48 subjects with IBC and 42 patients with AM. No statistical differences were revealed between the two groups for morphology of masses and of non-mass-like enhancement, breast enlargement, diffuse skin thickening, abnormal nipple configuration, prominent vessels, and also for cutaneous/subcutaneous, perimamillar and diffuse oedema. However, initial and postinitial dynamic characteristics significantly differed between the two groups (p < 0.001). In IBC, more masses with a greater average size were detected (p < 0.05). The following morphological criteria were also observed more often in IBC (p < 0.05): T2-hypointensity of masses (77.5%/18.2%), blooming sign (62.5%/31.8%), infiltration of pectoralis major muscle (interruption of fat plane: 54.2%/16.7%; pathological enhancement: 33.3%/7.1%), perifocal (66.7%/33.3%), prepectoral (72.9%/31.0%) and intramuscular pectoral oedema (41.7%/7.1%). The main localisation of AM was subareolar, of IBC central or dorsal (p < 0.001). The discrimination between AM and IBC remains a diagnostic challenge because of overlapping imaging features. However, the combination of multiple dynamic and morphological MRM criteria seems to have the potential for a differential diagnosis.

Inflammatory Breast Carcinoma in Magnetic Resonance Imaging: A Comparison with Locally Advanced Breast Cancer

RATIONALE AND OBJECTIVES Although inflammatory breast carcinoma (IBC) accounts for 1%-4% of all breast cancer cases, the appearance of this highly malignant tumor in magnetic resonance imaging (MRI) is still not well characterized. The aim of this study was to identify typical imaging features of IBC in comparison with noninflammatory locally advanced breast carcinoma (LABC). MATERIALS AND METHODS MRIs of 48 patients with IBC were compared with an equivalent cohort of 52 subjects with LABC. Age and histopathologic subtype were equivalent between the two groups. To delineate characteristic features, a multitude of dynamic and morphologic parameters were evaluated using T1- and T2-weighted sequences. RESULTS No significant differences of prevalences could be found for the following criteria: dynamic tumor signal characteristics, prominent vessels, perifocal edema, axillary lymph node involvement, morphology of focal masses, and morphologic pattern of non-mass like enhancement. Otherwise, the quantity of focal masses and the spatial distribution of the tumoral infiltration significantly differed between the two cancer groups. The following parameters occurred more frequently in the IBC cases: edema (cutaneous/subcutaneous 81.3%, perimamillar 70.8%, diffuse 89.6%, prepectoral 72.9%, intramuscular pectoral 41.7%), thickening (75.0%) and pathologic enhancement (60.4%) of Coopers ligaments, skin thickening (83.3%), punched-out sign (initially strong, focal increase of some dermal or subcutaneous parts followed by slow-continuous enhancement of the surrounding skin; 56.3%). CONCLUSIONS Inflammatory breast carcinoma seems to represent a specific biological entity resulting in typical MRI characteristics. Some of the parameters are supposed to visualize the characteristic extensive lymphovascular infiltration and therefore may improve the diagnosis of IBC.

MRI-guided interventions of the breast

MRI has proven to be a very reliable diagnostic tool in the detection and differential diagnosis of breast lesions. Some lesions are, even in retrospect, not detectable in x‐ray or ultrasound images but MRI is able to detect lesions at a much smaller size than the average size of lesions depicted by x‐ray and ultrasound. The aim in the future is to develop combined procedures where imaging, biopsy, and interventional therapies are combined in a single outpatient procedure. As a step toward this goal different interventional procedures are useful that include interstitial laser therapy (ILT), radiofrequency ablation (RFA), high‐intensity focused ultrasound (HIFU), microwave ablation therapy, and cryotherapy. In this overview the main features and initial results of these procedures are described and discussed. J. Magn. Reson. Imaging 2008;27:347–355.

Clinical MR-mammography: are computer-assisted methods superior to visual or manual measurements for curve type analysis? A systematic approach.

RATIONALE AND OBJECTIVES Enhancement characteristics after administration of a contrast agent are regarded as a major criterion for differential diagnosis in magnetic resonance mammography (MRM). However, no consensus exists about the best measurement method to assess contrast enhancement kinetics. This systematic investigation was performed to compare visual estimation with manual region of interest (ROI) and computer-aided diagnosis (CAD) analysis for time curve measurements in MRM. MATERIALS AND METHODS A total of 329 patients undergoing surgery after MRM (1.5 T) were analyzed prospectively. Dynamic data were measured using visual estimation, including ROI as well as CAD methods, and classified depending on initial signal increase and delayed enhancement. RESULTS Pathology revealed 469 lesions (279 malignant, 190 benign). Kappa agreement between the methods ranged from 0.78 to 0.81. Diagnostic accuracies of 74.4% (visual), 75.7% (ROI), and 76.6% (CAD) were found without statistical significant differences. CONCLUSIONS According to our results, curve type measurements are useful as a diagnostic criterion in breast lesions irrespective of the method used.

Combined magnetic resonance imaging of deep venous thrombosis and pulmonary arteries after a single injection of a blood pool contrast agent.

ObjectiveAgreement rate between magnetic resonance imaging (MRI) and Doppler ultrasound (DUS) for the detection of deep vein thrombosis (DVT) in the lower extremities was attempted by using the intravascular MRI contrast agent gadofosveset trisodium. The potential of this method to detect pulmonary embolism (PE) was also evaluated.Material and MethodsForty-three consecutive inpatients with ultrasound-confirmed DVT but no clinical signs of PE were prospectively enrolled in this feasibility study. MRI was performed after a single injection of gadofosveset trisodium. The pulmonary arteries were imaged using a 3D Fast Low Angle Shot (FLASH) gradient recalled echo sequence. Additionally, pulmonary arteries, abdominal veins, pelvic and leg veins were imaged using a fat-suppressed 3D gradient echo Volume Interpolated Breath-hold Examination (VIBE FS).ResultsGadofosveset trisodium-enhanced MRI detected more thrombi in the pelvic region, upper leg and lower leg than the initial DUS. In addition, PE was detected in 16 of the 43 DVT patients (37%).ConclusionThis study shows the feasibility of a combined protocol for the MRI diagnosis of DVT and PE using gadofosveset trisodium. This procedure is not only more sensitive in detecting DVT compared to standard DUS, but is also able to detect PE in asymptomatic patients.

Computer-aided interpretation of dynamic magnetic resonance imaging reflects histopathology of invasive breast cancer

ObjectiveTo perform a semiautomated software-based comparison of invasive breast carcinoma dynamic enhancement patterns in MR mammography with histological prognostic factors considering whole lesion volumes.Material and methodsA total of 128 patients with 145 invasive breast carcinomas underwent dynamic MR mammography. Kinetic features from the invasive breast lesions were obtained using commercially available software to automatically assess volume enhancement characteristics of a manually chosen lesion. Findings were compared with histological factors determining tumour aggressiveness (lymph node status, LN; oestrogen/progesterone receptor (ER/PR) status; HER-2/neu status; tumour grade) by using nonparametric rank tests and binary logistic regression analysis (BLRA).ResultsVolume enhancement characteristics were significantly influenced by LN, ER/PR and HER-2/neu status (P < 0.05). BLRA implied that total lesion and plateau voxel volume were independent predictors of ER/PR and HER-2/neu status. Strongest initial enhancement predicted negative ER/PR, and time to peak of the most suspect curve was inversely correlated with positive LN status. On the other hand, no statistical significance could be observed between histological tumour grading and kinetic features.ConclusionHistopathological criteria associated with poor prognosis lead to significantly more aggressive dynamic enhancement patterns in MR mammography. In this study, higher lesion volumes as well as higher and earlier initial enhancement were independent covariates predicting higher tumour aggressiveness.

Application of computer-aided diagnosis (CAD) in MR-mammography (MRM): do we really need whole lesion time curve distribution analysis?

RATIONALE AND OBJECTIVES The identification of the most suspect enhancing part of a lesion is regarded as a major diagnostic criterion in dynamic magnetic resonance mammography. Computer-aided diagnosis (CAD) software allows the semi-automatic analysis of the kinetic characteristics of complete enhancing lesions, providing additional information about lesion vasculature. The diagnostic value of this information has not yet been quantified. MATERIALS AND METHODS Consecutive patients from routine diagnostic studies (1.5 T, 0.1 mmol gadopentetate dimeglumine, dynamic gradient-echo sequences at 1-minute intervals) were analyzed prospectively using CAD. Dynamic sequences were processed and reduced to a parametric map. Curve types were classified by initial signal increase (not significant, intermediate, and strong) and the delayed time course of signal intensity (continuous, plateau, and washout). Lesion enhancement was measured using CAD. The most suspect curve, the curve-type distribution percentage, and combined dynamic data were compared. Statistical analysis included logistic regression analysis and receiver-operating characteristic analysis. RESULTS Fifty-one patients with 46 malignant and 44 benign lesions were enrolled. On receiver-operating characteristic analysis, the most suspect curve showed diagnostic accuracy of 76.7 +/- 5%. In comparison, the curve-type distribution percentage demonstrated accuracy of 80.2 +/- 4.9%. Combined dynamic data had the highest diagnostic accuracy (84.3 +/- 4.2%). These differences did not achieve statistical significance. With appropriate cutoff values, sensitivity and specificity, respectively, were found to be 80.4% and 72.7% for the most suspect curve, 76.1% and 83.6% for the curve-type distribution percentage, and 78.3% and 84.5% for both parameters. CONCLUSIONS The integration of whole-lesion dynamic data tends to improve specificity. However, no statistical significance backs up this finding.

Sensitivity and Specificity of Unilateral Edema on T2w-TSE Sequences in MR-Mammography Considering 974 Histologically Verified Lesions

Abstract:  The objective of this investigation was to determine the diagnostic value of unilateral edema in differentiating benign from malignant breast disease on T2w‐TSE images in MR‐Mammography (MRM). All patients from a 10‐year period undergoing surgery in the same institution after having received MRM in our department were included in this prospective analysis of previous acquired examinations. To eliminate bias caused by prior procedures, all patients having had biopsy, operation, radiation therapy, or chemotherapy before MRM were excluded. T2w‐TSE images were acquired after a dynamic contrast‐enhanced series of T1‐weighted images in a standardized examination protocol (1.5 T). Edema was defined as a high‐signal intensity on T2w‐TSE images and it was categorized as absent, perifocal, or diffuse. Examinations were rated by two experienced observers blinded to all procedures and results following MRM. In cases of disconcordance, the opinion of a third radiologist decided. Statistical testing included Pearson’s Chi‐squared test and Fisher’s exact testing. A total of 1,010 patients with a mean age of 55 years (SD: 11.6 years, range: 16–87 years) with 1,129 histologically verified lesions were included in this investigation. After removing all patients with prior procedures from the patient collective, 974 lesions were left for statistical analysis. Perifocal edema was highly significantly (p < 0.001) associated with malignant disease, leading to a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 33.5%, 93.9%, 89.6, and 57.1%, respectively. Unilateral edema in general showed the following diagnostic parameters: sensitivity 53.0%, specificity 80.5%, PPV 80.9%, and NPV 52.3%. Edema seems to be associated with malignancy in the majority of cases. Especially, specificity and PPV were found to be high. These findings may be helpful in diagnostic decisions on otherwise equivocal cases.