- Pictorial Review
- Open Access
MR imaging of the reconstructed breast: What the radiologist needs to know
© European Society of Radiology 2012
- Received: 14 January 2012
- Accepted: 23 January 2012
- Published: 17 March 2012
The objective is to review the different types of breast reconstruction following cancer surgery and describe expected imaging appearances and complications seen in the reconstructed breast.
Surgical management of breast cancer often entails lumpectomy or mastectomy. When mastectomy is performed, patients often opt for breast reconstruction. Most facilities do not routinely image the reconstructed breast with mammography.
However, many of these women are imaged with screening breast MRI for evaluation of the contralateral breast, or they may develop a clinical problem that warrants a diagnostic evaluation with MRI. In this article, we will review the more commonly encountered types of breast reconstruction, which include implants, tranversus rectus abdomnis flap, latissimus dorsi flap, deep inferior epigastric perforator flap, and gluteal flaps. Each of these types of reconstruction has different appearances on MR. We will also discuss potential complications that can be seen in the reconstructed breasts, including fat necrosis and recurrence.
Radiologists will better understand the different types of breast reconstruction after mastectomy and their normal imaging appearance on MRI. Radiologists will be more aware of how to recognize complications related to surgery as well as how to determine whether recurrence is present.
• The different surgical techniques used in breast reconstruction are discussed.
• Describes the normal magnetic resonance imaging appearance of the breast after reconstruction.
• Identify MR imaging features of benign sequelae and recurrence following breast reconstruction.
- MRI imaging
- Types of breast reconstruction
- MRI imaging of reconstructed breast
Surgical management of breast cancer often entails lumpectomy or mastectomy, followed usually by breast reconstruction. Each of these types of reconstruction has different appearances on magnetic resonance imaging (MRI) examinations. Understanding the expected anatomic appearance of the breast subsequent to breast reconstruction is critical in the interpretation of MRI following surgery. It is also important to be aware of the potential complications seen in the reconstructed breast and their MRI appearances.
In our institution, breast MRI is performed at 1.5-T (GE Healthcare, Milwaukee, WI, USA) to produce high-spatial-resolution images in the axial plane. Unenhanced fat-saturated T1-weighted (T1W) images are obtained followed by contrast-enhanced acquisition of fat-saturated T1W images with data at three time points, in consecutive 3- to 5-min intervals. Delayed sagittal T1W fat-saturated images are also obtained. In addition, T2W nonfat-saturated images are obtained, which gives architectural information. The contrast agent gadopentetate dime-glumine (Magnevist, Bayer Schering Pharma) was administered intravenously at a dose of 0.1 mmol/kg body weight with an MRI-compatible remote control power injector at a rate of 1.2 ml/s in all studied patients. The contrast injection was followed by a 10-ml saline flush administered at the same flow rate. The imaging parameters were as follows: TR/TE, 9/4.4; flip angle, 10°; number of signals acquired, 1; acquisition matrix, 512 × 512; section thickness, 2 mm.
Common problems in MRI of reconstructed breasts are failure of fat suppression and inhomogeneous fat suppression. Field homogeneity can be improved by adjustment of the shim gradients and ensuring that shim volumes adequately cover the breast tissue. In addition, the center frequency should be adjusted to the center of the water peak for optimal fat suppression. If fat suppression remains a problem, images can be obtained without fat suppression while the patient is instructed to remain very still. Subtraction images can then be used for interpretation.
Given that there are few articles on this topic in the radiology literature, we studied the patients with breast reconstructions who had an MRI at our institution to understand different types of reconstructions performed by the surgeons and the encountered complications.
Different surgical techniques used in breast reconstruction
Autologous flap reconstruction
+/− Acellular matrix (AlloDerm, Allomax, etc.)
+/− Latissimus muscle flap with implant
Transplantation of a transverse rectus abdominis myocutaneous (TRAM)
Reconstruction with the latissimus dorsi myocutaneous flap
(B) Free flap
DIEP/SIEA (Deep inferior epigastric artery perforator flap/superficial inferior epigastric artery flap)
SGAP/IGAP (Superior gluteal artery perforator flap or inferior gluteal artery perforator flap)
TUG (Transverse upper gracilis flap)
The indications, contraindications, disadvantages, and advantages of breast reconstruction
TRAM (Pedicle/free flap)
Perforator flap surgery DIEP/SIEP/SGAP/IGAP/TUG
Patients with inadequate in-situ donor tissue
Radical mastectomy defect with large tissue requirement
Autogenous tissue reconstruction is preferred to avoid sacrifice of the muscle tissues traditionally associated with these techniques
Patients who cannot tolerate increased length of surgery required for pedicle reconstruction
History of radiation to the chest wall
Previous abdominal operations (including abdominoplasty)
Unsatisfactory or previously failed implant reconstruction
Shorter recovery time
Large opposite breast (difficult to match with an implant)
Preferred dorsal donor site
As a replacement for implants in cases of severe capsular contracture, which is more often found in patients who have required radiation therapy
Moderate to severe obesity
Small opposite breast (difficult to match with an implant)
Failed implant or TRAM reconstruction
Autogeneous tissue reconstruction is one option available for restoring form in those with deformities from volume loss due to prior lumpectomy, radiation, or subcutaneous mastectomy
Patients who are undergoing bilateral reconstruction but are otherwise candidates for transverse rectus abdominis muscle (TRAM) reconstruction may be considered for implant-expander reconstruction to avoid the morbidity of using both rectus muscles
Previous failure of implant reconstruction
Patients desiring future pregnancy
Congenital breast absence or underdevelopment (Poland syndrome)
Excess lower abdominal tissue and patient desires abdominoplasty
Insufficient skin and/or subcutaneous tissue to cover the implant
Inadequate excess abdominal tissue
Prior procedure that may have injured the vessels that perforate the rectus sheath (i.e., abdominoplasty)
Relative contraindication: significant ptosis of the contralateral breast as implants are unable to achieve a natural ptotic appearance; in these patients, autologous tissue reconstruction or a contralateral symmetry procedure is indicated
Certain abdominal incisions from previous surgical operations may have inadvertently caused a disruption in the necessary blood supply to the TRAM flap
Implants not desired
Routine abdominal operations such as cesarean delivery, hysterectomy, appendectomy, cholecystectomy, and laparoscopic procedures do not usually pose a problem
Patients with a history of smoking, hypertension, obesity, chronic obstructive airways disease, previous abdominal surgery, and diabetes mellitus are considered high risk (may choose pedicle flap technique)
Severe cardiac disease
Smoking is often problematic. An absolute minimum of 3 weeks of smoking cessation is recommended before surgery
Severe pulmonary disease
More natural tissue and natural result, but usually still needs/requires implant
Shorter operation, shorter recovery
Very natural looking
Decreases risk associated with implant and radiation
Very natural looking
Minimal scarring to rest of the body
Ages with patient
Longer initial surgery
Ages with patient
No muscle trauma
Less fat necrosis-better blood supply
Minimal abdominal weakness and abdominal hernia
Overall complication rate is 10.5% with implant-based reconstruction. Most common complications are infection (4 %), followed by malposition (3.5%), rupture (1.7%), extrusion (0.6%), and capsular contracture (0.6%) 
Complete removal of rectus, decreased with placement of mesh path 
Lose muscle function-initial shoulder weakness 15-20%
Technically difficult operation
Altered tension on thoracolumbar fascia- back pain
Synergistic muscle compensation (teres major, subscapularis, pectoralis major)
Risks associated with microsurgery
Decreased abdominal strength, especially pronounced with bilateral procedure
Postmastectomy reconstruction with a tissue expander and implant involves a staged approach. A tissue expander is a temporary device placed on the chest wall deep to the pectoralis major muscle, which may be performed immediately following the mastectomy or as a delayed procedure. The purpose is to create a soft pocket to contain the permanent implant. Tissue expanders are available in a variety of shapes and sizes. Certain tissue expanders have a magnet filling port and are not MRI compatible. When it is first positioned, it is partially filled with saline. Within a few weeks, once the patient has healed, expansion is started as an outpatient procedure at 1-, 2-, or 3-week intervals over several months. The timing of expansion can be coordinated with chemotherapy treatments.
Once expansion is completed and the patient is medically cleared for another operation (about 1 month after chemotherapy), the second stage of reconstruction is performed. This is an outpatient procedure that involves exchanging the expander for an implant and creating a more refined breast shape. The initial tissue expander placement and the subsequent exchange for an implant each take about 1 h in the operating room. Implant-based reconstruction may be combined with acellular dermal matrix coverage or with a lattisimus dorsi flap.
AlloDerm is isointense to glandular parenchyma on T1W images and does not enhance with gadolinium. It will be seen overlying the implant, filling the gap between the skin and the implant (Figs. 1b, c). The figures help identify the normal appearance of AlloDerm.
On the MR images, the latissimus dorsi muscle flipped inferiorly for reconstruction is well appreciated. The flap consists of the latissimus dorsi muscle and its overlying skin and fat flipped and tunneled from the back to and from the neobreast, giving a tailed appearance to the muscle in the lateral breast. This can be used as a differentiator on imaging from TRAM flap reconstruction. This atrophies over time, showing fatty strands within. The denuded dermal layer is seen parallel to the skin of the breast (Fig. 2).
The pedicled TRAM flap is based on the superior epigastric vasculature and requires the full length of the rectus abdominis muscle. The harvested muscle and lower abdominal soft tissue are elevated and tunneled subcutaneously into the mastectomy defect. The portion of the abdominal epidermis that is used to create the skin surface of the neobreast remains intact, whereas the remainder is de-epithelialized. The contralateral rectus abdominis muscle is more commonly used for unilateral reconstruction. When bilateral reconstruction is performed, the ipsilateral rectus abdominis muscle is used in order to prevent crossing of the pedicles and subsequent potential vascular compromise.
The free TRAM flap derives its blood supply from the inferior epigastric artery and vein. The inferior epigastric is chosen, as the blood supply via the superior epigastric artery is attenuated along its course by multiple tendinous inscriptions and is less robust. These vessels are ligated and microsurgically re-anastomosed in the chest to the thoracodorsal, subscapular, or internal mammary artery and vein. The microsurgical technique is preferred in patients with relative risk factors for atherosclerosis including obesity, diabetes mellitus, smoking, and cardiovascular disease, as well as in those patients who have undergone prior abdominal surgery . Compared with the pedicled flap, the free flap requires a smaller amount of rectus abdominis muscle, resulting in decreased prevalence of abdominal wall hernia.
Normal MR imaging appearance of transplantation of a transverse rectus abdominis myocutaneous (TRAM) flap
The most familiar changes of TRAM flap reconstruction include the replacement of the normal glandular tissue of the breast with lower abdominal fat and the presence of atrophied rectus abdominis muscle along the anterior chest wall (Fig. 3). Note in TRAM reconstruction the bulk of the flap is usually in the center on the MRI image especially on the axial images, as oppposed to the latissimus flaps where the flap consisting of the latissimus dorsi muscle and its overlying skin and fat is rotated and tunneled from the back to the neobreast, giving a tailed appearance to the muscle in the lateral breast. This can be used as a differentiator on imaging.
The Deep inferior epigastric artery perforator (DIEP) and superficial inferior epigastric artery (SIEA) flaps transfer the same tissue from the abdomen to the chest for breast reconstruction as the TRAM flap without sacrificing the rectus muscle or fascia. The DIEP flap is supplied by intramuscular perforators from the deep inferior epigastric artery and vein. The SIEA flap is based on the SIEA and vein, which arise from the common femoral artery and saphenous bulb.
TheGAP flaps are based on perforators from either the superior or inferior gluteal artery (Fig. 5). The superior gluteal artery perforator (S-GAP) flap is the preferred method of breast reconstruction when the abdomen is not available or preferable . Gluteal artery perforator (GAP) flaps allow transfer of tissue from the buttock, also with minimal donor-site morbidity.
The transversus upper gracilis (TUG) flap procedure uses tissue from the inner portion of the upper thigh (just under the groin crease) for breast reconstruction (Fig. 5). Loss of the gracilis muscle does not result in any noticeable functional impairment. The ideal shape of the TUG flap allows shaping of the breast with a very aesthetic contour and projection.
Free flap reconstruction on MRI shows replacement of the normal glandular tissue of the breast with tissue from the lower abdomen, buttocks, or thigh fat. It also shows a thin vascular pedicle that is anastomosed by microsurgical technique to the internal mammary artery (Fig. 4, 5).
All free flap reconstructions show the reconstructed breast constituted of fat and the vascular pedicle, which is the anastomosis site to the internal mammary artery. There is no muscle seen in these as opposed to the TRAM or latissimus reconstruction, which has atrophied muscle along the chest wall.
In the postoperative breast, radiation-induced changes, including fibrosis and skin thickening complicate clinical evaluation, and distortion of normal breast architecture confounds physical examination and mammographic assessment of the breast. MR imaging has been demonstrated to be extremely useful for demonstrating clinically occult breast cancer, identifying unsuspected multifocal cancer and differentiating benign postoperative findings from recurrent breast cancer. The specificity of MR imaging in the irradiated breast may vary, with more prominent enhancement present for up to 1 year following radiation treatment, and enhancement may be present for several years.
Seromas and hematomas may be seen after breast reconstruction surgery. Seromas may demonstrate unilocular or complex T2 bright signal. Hematomas show variable signal intensity on T1- and T2-weighted images depending on the evolution of the blood products. In addition, they often demonstrate a low-signal-intensity rim of hemosiderin. Uniform rim enhancement may be seen, but there should be no solid or internal enhancement within a postoperative seroma or hematoma.
Fat necrosis is a benign noninfectious inflammatory process of adipose tissue that is characterized histologically by necrotic fat cells with peripheral fibrosis and inflammatory cells. It is a common complication of TRAM flap reconstruction, with rates as high as 25% quoted in the literature. The cause is attributed to the marginally adequate blood supply in the periphery of the soft-tissue flap. Fat necrosis is often palpable, manifesting as a firm mass at physical examination, and the appearance can mimic that of tumor recurrence at both clinical evaluation and mammography.
Malignant findings after flap reconstruction
De novo carcinoma
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