Fat Necrosis of the Breast

Rationale and Objectives

This study aims to describe the magnetic resonance imaging (MRI) features of fat necrosis on magnetic resonance mammography, which may downstage a suspicious lesion to a merely benign finding.

Materials and Methods

This prospective study included 82 female patients (mean age 50 years) who were diagnosed to have suspicious lesions by mammography, ultrasonography or both. All patients underwent MRI including diffusion-weighted imaging and spectroscopy. Image postprocessing and analysis included signal intensity, enhancement characteristics, diffusion restriction, and spectroscopic analysis. All patients underwent histopathological analysis for confirmation. Sensitivity, specificity, positive predictive value (PPV), and negative (NPV) predictive value were calculated.

Results

To label a lesion as fat necrosis on MRI analysis, presence of fat signal in a lesion revealed sensitivity of 98.04%, specificity of 100%, PPV of 100%, and NPP of 96.88%, whereas nonenhancement of the lesion itself revealed sensitivity of 96.08%, specificity of 100%, PPV of 100%, and NPP of 93.94%. However, adding both the nonrestriction on diffusion analysis and the lack of tCholine at 3.22 ppm increased the sensitivity and specificity to 100%, as well as PPV of 100% for fat necrosis and hence a NPV for malignancy of 100%.

Conclusions

MRI proved to be of value in differentiating fat necrosis from malignancy based on the molecular composition of fat necrosis, clearly depicted by MRI without the need for invasive confirmation by biopsy.

Introduction

Fat necrosis is a benign non–suppurative inflammatory process of adipose tissue , initially described in the breast in 1920s . It is described as “an innocent lesion” in medical literature labeled as BI-RADS 2, which stands for totally benign breast lesion if it met its classical oil cyst form on mammogram. Nonetheless, it gained its notorious reputation and clinicians thrive to diagnose it accurately, as it is the number one differential diagnosis of an early breast cancer . Before the era of imaging and tissue biopsy, the treatment of choice was a wide resection of the breast .

Even with the advent of the different breast imaging procedures, fat necrosis still displays a wide spectrum of morphologic criteria on the different imaging modalities. This depends on the pathological stage of fat necrosis process, which depends on the balance of fat content and the degree of inflammation and fibrosis of the lesions .

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Materials and Methods

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Patients

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At the end of the year, we ended up with 82 female patients (mean age ± SD: 50.10 ± 10.55, age ranging between 34 and 76 years), with 58 being suspected for postmanagement recurrence, whereas the rest were newly diagnosed lesions.

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MRI

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MRI Protocols and Technique

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Image Post Processing

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Lesion Evaluation and Interpretation of Examination

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Histopathological Analysis

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Data and Statistical Analysis

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Results

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MRI Findings

Morphology and Signal Intensity

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Enhancement Characteristics

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Diffusion-weighted Imaging (DWI) and Spectroscopic Analysis

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BI-RADS Classification

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Radiologic-Pathologic Correlation of Cases with Fat Necrosis

Morphology and Signal Intensity

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Table 1

MRI Findings of Pathologically Proven Cases of Fat Necrosis

MRI Characteristics Number of Cases Total T1 intensity Hyperintense 50 51 Hypointense (signal void) 1 T2 fat-suppressed intensity Black hole effect (markedly hypointense) 50 51 Signal void 1 Lesion’s enhancement Enhancing rim with nonenhancing center 38 51 Nonenhancement of both center and surrounding fibrosis 11 Diffuse enhancement 2 Diffusion-weighted imaging Nonrestricted (≥1.5 × 10 −3 mm 2 /s) 42 51 Overlap zone (>1.3 × 10 −3 mm 2 /s) (<1.3 × 10 −3 mm 2 /s) 9 0 Restricted (≤1.0 × 10 −3 mm 2 /s) 0 Spectroscopic analysis Positive (at 3.22 ppm) 0 15 Positive (>3.28 ppm) 4 Negative (at 3.2 ppm and >3.28 ppm) 11

MRI, magnetic resonance imaging.

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Enhancement Characteristics

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DWI and Spectroscopic Analysis

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Diagnostic Performance

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Discussion

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References

1. Tan P.H., Lai L.M., Carrington E.V., et. al.: Fat necrosis of the breast—a review. The Breast 2006; 15: pp. 313-318.
2. Chan L.P., Gee R., Keogh C., et. al.: Imaging features of fat necrosis. AJR Am J Roentgenol 2003; 181: pp. 955-959.
3. Daly C.P., Jaeger B., Sill D.S.: Variable appearances of fat necrosis on breast MRI. AJR Am J Roentgenol 2008; 191: pp. 1374-1380.
4. Taboada J.L., Stephens T.W., Krishnamurthy S., et. al.: The many faces of fat necrosis in the breast. AJR Am J Roentgenol 2009; 192: pp. 815-825.
5. Kerridge W.D., Kryvenko O.N., Thompson A., et. al.: Fat necrosis of the breast: a pictorial review of the mammographic, ultrasound, CT, and MRI findings with histopathologic correlation. Radiol Res Pract 2015; 2015: pp. 613139.
6. Chala L.F., de Barros N., Moraes P., et. al.: Fat necrosis of the breast: mammographic, sonographic, computed tomography, and magnetic resonance imaging findings. Curr Probl Diagn Radiol 2004; 33: pp. 106-126.
7. Sergi Ganau S., Tortajada L., Escribano F., et. al.: The great mimicker: fat necrosis of the breast—magnetic resonance mammography approach. Curr Probl Diagn Radiol 2009; 38: pp. 189-197.
8. Stanwell P., Gluch L., Clark D., et. al.: Specificity of choline metabolites for in vivo diagnosis of breast cancer using 1H MRS at 1.5 T. Eur Radiol 2005; 15: pp. 1037-1043.
9. Sardanelli F., Fausto A., DiLeo G., et. al.: In vivo proton MR spectroscopy of the breast using the total choline peak integral as a marker of malignancy. AJR Am J Roentgenol 2009; 192: pp. 1608-1617.
10. Partridge S.C., DeMartini W.B., Kurland B.F., et. al.: Quantitative diffusion-weighted imaging as an adjunct to conventional breast MRI for improved positive predictive value. AJR Am J Roentgenol 2009; 193: pp. 1716-1722.
11. Kul S., Cansu A., Alhan E., et. al.: Contribution of diffusion weighted imaging to dynamic contrast-enhanced MRI in the characterization of breast tumors. AJR Am J Roentgenol 2011; 196: pp. 210-217.
12. Gonzales M.A., Castañon A.I., Baltar N., et. al.: Diffusion weighted MR imaging assessment after breast conservative treatment. Poster session in ECR 2012 Educational Exhibit. March 1–52012. Vienna, Austria
13. Şahin C., Arıbal E.: The role of apparent diffusion coefficient values in the differential diagnosis of breast lesions in diffusion-weighted MRI. Diagn Interv Radiol 2013; 19: pp. 457-462.
14. Hassan H.H.M., Zahran M.H.M., Hassan H.E., et. al.: Diffusion magnetic resonance imaging of breast lesions: initial experience at Alexandria University. Alexandria J Med 2013; 49: pp. 2652-2672.
15. Hetta W.: Role of diffusion weighted images combined with breast MRI in improving the detection and differentiation of breast lesions. Egypt J Radio Nuc Med 2015; 46: pp. 259-270.
16. Tsushima Y., Takahashi-Taketomi A., Endo K.: Magnetic resonance (MR) differential diagnosis of breast tumors using apparent diffusion coefficient (ADC) on 1.5-T. J Magn Reson Imaging 2009; 30: pp. 249-255.
17. Chansakul T., Lai K.C., Slanetz P.J.: The post-conservation breast: part 2, imaging findings of tumor recurrence and other long-term sequelae. AJR Am J Roentgenol 2012; 98: pp. 331-333.
18. Trimboli R.M., Carbonaro L.A., Cartia F., et. al.: MRI of fat necrosis of the breast: the “black hole” sign at short tau inversion recovery. Eur J Radiol 2012; 81: pp. e573-e579.
19. Sardanelli F., Carbonaro L.A., Montemezzi S., et. al.: Clinical breast MR using MRS or DWI: who is the winner?. Front Oncol 2016; 6: pp. e217.

Fat Necrosis of the Breast

Rationale and Objectives

Materials and Methods

Results

Conclusions

Introduction

Materials and Methods

Patients

MRI

MRI Protocols and Technique

Image Post Processing

Lesion Evaluation and Interpretation of Examination

Histopathological Analysis

Data and Statistical Analysis

Results

MRI Findings

Morphology and Signal Intensity

Enhancement Characteristics

Diffusion-weighted Imaging (DWI) and Spectroscopic Analysis

BI-RADS Classification

Radiologic-Pathologic Correlation of Cases with Fat Necrosis

Morphology and Signal Intensity

Enhancement Characteristics

DWI and Spectroscopic Analysis

Diagnostic Performance

Discussion

References

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