Breast reconstruction with autologous tissue flaps: a pictorial review Poster No.:

C-1173

Congress:

ECR 2016

Type:

Educational Exhibit

Authors:

A. Carvalho, P. Leitão, B. M. Araujo, N. P. Silva, A. S. R. Preto; Porto/PT

Keywords:

Multidisciplinary cancer care, Cancer, Surgery, Diagnostic procedure, Ultrasound, MR, Mammography, Breast, Abdomen

DOI:

10.1594/ecr2016/C-1173

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Learning objectives To review the technical aspects of the different types of breast reconstruction surgery techniques. To describe and illustrate the normal and abnormal imaging findings observed in patients following breast reconstruction with autologous tissue flaps.

Background Advances in breast imaging techniques have led to increased breast cancer detection rates and thus improved overall survival over the past few decades. At present time, although breast conservation is possible in many more cases than it used to be, some women still undergo mastectomy for breast cancer treatment. Breast reconstruction is an important component of multidisciplinary breast cancer care and yields positive psychological benefits for the patient. Surgical techniques for breast reconstruction can be divided in 3 groups: (1) implant-based techniques; (2) autologous tissue-based techniques and (3) a combination of both. In this work, we will focus on normal and abnormal imaging findings after breast reconstruction with the most frequent autologous tissue-based techniques. These include the latissimus dorsi myocutaneous flap and the abdominal based-flaps, such as the pedicled or free transverse rectus abdominis myocutaneous (TRAM) flap and the deep inferior epigastric perforator (DIEP) flap.

Findings and procedure details th

Breast implant procedures have been performed since the late 19 century for augmentation, correction of congenital abnormalities and breast reconstruction after mastectomy. However, advances in microsurgery over the past few years have led to the increasingly frequent use of autologous tissue flaps, which is a method that provides better cosmetic result and a more natural texture of the reconstructed breast.

LATISSIMUS DORSI MYOCUTANEOUS FLAP (Fig. 1 on page 8)

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First described by Transini in 1987, the latissimus dorsi myocutaneous flap is created from a portion of the muscle harvested from the middle back along with subcutaneous tissue and the thoracodorsal vessels. The surgical technique involves the creation of a subcutaneous tunnel across the axilla to the mastectomy site. This flap is usually selected when additional tissue is needed to reconstruct mastectomy defects. However, it frequently requires an additional breast implant to achieve symmetry with the contralateral breast, as the amount of tissue harvested is often insufficient.

Advantages • • • •

Less surgery time Does not result in abdominal wall weakness Robust vascular supply Remains a good option for slim patients who lack sufficient abdominal fat

Disadvantages • • •

Worst esthetic result compared with TRAM and DIEP flaps Usually leaves a large scar on the middle back Seroma and hematoma are frequent complications at the donor site

TRANSVERSE RECTUS ABDOMINIS MYOCUTANEOUS (TRAM) FLAPS First reported in 1979 by Holmstrom, the TRAM flaps are currently the most widely used autologous tissue-based techniques in breast reconstruction. There are three main types of TRAM flap surgery: •

PEDICLED TRAM FLAP (Fig. 2 on page 8)

The classic pedicled TRAM flap contains skin, subcutaneous tissue and a portion of the rectus abdominis muscle along with its vascular supply, the superior epigastric vessels. The flap is then positioned in the breast reconstruction site by tunneling under the subcutaneous tissue at the level of the xiphoid process. •

FREE TRAM FLAP (Fig. 3 on page 9)

This procedure involves harvesting skin, subcutaneous tissue and a smaller portion of the rectus abdominis muscle than in the classic pedicle TRAM flap. In this case, however, the vessels (deep inferior epigastric vessels) are ligated when the tissue is harvested

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and are subsequently reanastomosed end to end with the thoracodorsal or internal mammary vessels and the reconstruction site. This allows for an improved blood supply and subsequently the risk of fat necrosis is lower. There is also no need for tunneling under the skin and it leads to less abdominal wall weakness. •

FREE MUSCLE SPARING TRAM FLAP

This technically advanced procedure involves a less invasive excision of the rectus abdominis muscle based on the precise and targeted identification of each deep inferior epigastric perforating vessels in the flap. This requires identification of clinically relevant perforating branches with CT angiography before the surgical procedure.

Advantages of the TRAM flaps • •

More natural breast texture and better overall esthetic result Abdominoplasty can be performed in the same surgical time

Disadvantages of the TRAM flaps • • •

Requires greater expertise and more operating room time Loss of abdominal wall strength and increased incidence of abdominal wall hernias Recovery from surgery is usually longer and painful

DEEP INFERIOR EPIGASTRIC PERFORATOR (DIEP) FLAP (Fig. 4 on page 10) Koshima and Soeda introduced the DIEP flap in 1989. This is the most evolved form of breast reconstruction available today. The procedure involves microdissection of perforator arteries arising from the deep inferior epigastric artery and posterior anastomosis with the internal mammary vessels. As with the free muscle-sparing TRAM flap, this usually requires vascular mapping with CT angiography of the abdomen for preoperative planning. The flap is composed of an elliptical portion of the lower abdominal skin and subcutaneous tissue and the creation of a DIEP flap does not involve excision of the rectus abdominis muscle.

Advantages:

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• • •

Good cosmetic result Reduction in donor site morbidity Faster recovery time after surgery

Disadvantages: • •

Complexity of the surgical procedure High risk of ischemic complications and fat necrosis

PRE-OPERATIVE IMAGING Pre-operative vascular mapping is key to the surgical planning of the newest breast reconstruction procedures (e.g. the DIEP flap and the free TRAM flap). CT angiography has surpassed Doppler ultrasonography as the ideal modality for mapping the perforator vessels and to assess their intramuscular course and routine use of CT angiography reduces the duration of the surgical procedure and the overall postoperative morbidity. The deep inferior epigastric artery (DIEA) arises from the distal external iliac artery immediately above the inguinal ligament and courses superiorly, penetrating the rectus sheath just below the arcuate line (Fig. 5 on page 12). A variety of branching patterns have been described. The perforating vessels arise anteriorly from the main artery, cross the rectus abdominis muscle and the anterior rectus sheath, supplying the abdominal wall fat and skin. The anatomic variables that should be considered to select and adequate perforator are (1) vessel size; (2) location relative to the umbilicus; (3) course and (4) length (Fig. 6 on page 13, Fig. 7 on page 13 and Fig. 8 on page 15)

NORMAL IMAGING FINDINGS RECONSTRUCTED BREAST

OF

THE

AUTOLOGOUS

TISSUE-BASED

In general, it is not possible to differentiate among the various types of flaps by imaging alone without prior knowledge of the patient's surgical history. Unlike implants, which are radiopaque, autologous tissue flaps are radiolucent and readily imaged at mammography. Autologous flaps present with predominantly fatty appearance with variable tissue density due to muscle component and postoperative

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scarring. The muscle component is seen most often in the mediolateral oblique (MLO) view. There are no parenchymal structures, ducts of Cooper ligaments (Fig. 9 on page 15, Fig. 10 on page 16) At ultrasound, autologous flaps appear as well-defined isoechoic tissue with hyperechoic septa (Fig. 9 on page 15) At CT and MRI, the appearance of autologous tissue flaps varies with the technique chosen. With latissimus dorsi myocutaneous flap, the muscle is seen flipped inferiorly along with its overlying skin and fat (Fig. 11 on page 17) With TRAM flaps, there is replacement of the normal glandular tissue of the breast with abdominal fat and the rectus abdominis muscle is seen atrophied along the anterior chest wall (Fig. 12 on page 17) With DIEP flap, MRI shows replacement of the glandular tissue with fat from the lower abdomen and it is usually possible to identify the microsurgically anastomosed vascular pedicle to the internal mammary artery (Fig. 13 on page 18). COMPLICATIONS FAT NECROSIS (5-35%) •

Refers to an area of firmness within adipose tissue that occurs after devitalization of fat.

•

Usually presents as a firm, palpable mass that can mimic a recurrent tumor.

•

At mammography, fat necrosis can present as a smooth-bordered lucent mass (lipid cyst, Fig. 14 on page 19), a cluster of pleomorphic micro or macrocalcifications (Fig. 15 on page 20), an irregular area of soft tissue density (Fig. 16 on page 21) or even a spiculated mass. It is usually located peripherally within the flap, where the blood supply is scarce.

•

At ultrasonography, can appear as a cyst with or without echogenic contents (Fig. 17 on page 22), a solid mass (Fig. 18 on page 23) with circumscribed or poorly defined margins or even as an area of increased attenuation due to calcification. A targeted ultrasound is usually the best approach to provide guidance for biopsy, when necessary.

•

At MRI, it is characterized by a round or irregular mass with central highsinal intensity on T1 weighted images without fat suppression and high signal intensity on T2WI. It can exhibit variable enhancement following gadolinium administration, but is typically peripheral and early, without washout (Fig. 19 on page 24).

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FLUID COLLECTIONS (SEROMAS AND HEMATOMAS) •

Seromas and hematomas are relatively common early after breast reconstruction and gradually resolve being replaced by scarring and fibrosis.

•

At ultrasonography, they usually present as anechoic fluid collections or with multiple internal septa (Fig. 20 on page 24, Fig. 21 on page 25).

•

At MRI, seromas demonstrate high signal intensity on T2WI and hematomas show more variable signal intensity on T1 and T2WI depending on evolution of blood products.

FIBROSIS •

As fibrosis is a common sequel of radiation therapy in the breast, atrophy and fibrosis of the muscle used in the flap are also seen in the reconstructed breast.

•

Fibrosis is best evaluated in MRI, presenting as an irregular mass characterized by lack of enhancement or by minimal enhancement following contrast material administration that gradually increases with time.

•

However, an enhancing soft tissue mass can be seen in the postoperative period for as long as 1 year after surgery because of the presence of granulation tissue. This is a common pitfall at MR imaging of the reconstructed breast.

RECURRENT CANCER (Fig. 22 on page 25, Fig. 23 on page 25) •

It is generally accepted that all breast tissue cannot be surgically removed completely after mastectomy, because portions often remain in the anterolateral aspect of the chest wall and axilla. Thus, although the risk for local recurrence of breast cancer is drastically reduced, it cannot be eliminated.

•

Recurrent carcinoma manifests clinically as a palpable mass or as skin thickening with or without associated cutaneous erythema. Local recurrences appear predominantly at the medial aspect of the flap due to lymphatic drainage to the internal mammary nodes, which are not dissected during mastectomy and reconstruction.

•

Although ongoing clinical surveillance is important to access for recurrent cancer, the use of screening mammography for reconstructed breasts is still controversial.

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•

At mammography, recurrent cancer resembles the primary tumor, appearing as a focal mass, distortion or suspicious microcalcifications.

•

At ultrasonography, common findings include a solid hypoechoic mass or an acoustic shadow, but it can resemble typical benign findings such as fat necrosis.

•

At MRI, it is depicted as a mass with low signal intensity on T1WI, intermediate or high signal intensity on T2WI and rapid enhancement following gadolinium administration.

Images for this section:

Fig. 1: Schematic representation of a latissimus dorsi myocutaneous flap. The flap, composed of muscle, skin and fat along with the thoracodorsal vessels is tunneled across the axilla to the mastectomy site. © Dialani V et al. (2012) MR imaging of the reconstructed breast: what the radiologist needs to know. Insights Imaging 3:201-213

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Fig. 2: Classic pedicled TRAM flap schematic representation. The flap consists of skin, subcutaneous fat and a portion of the rectus muscle and is tunneled subcutaneously to the mastectomy site, mantaining its original vascular supply. © Hogge J et al. (1999) Mammography of autologous myocutaneous flaps. Radiographics 19:S63-S72

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Fig. 3: Free TRAM flap schematic representation. In this surgical technique, the vessels are ligated and reanastomosed with the thoracodorsal or intermal mammary vessels. Hence, a smaller portion of rectus muscle is excised. © LePage MA et al. (1999) Breast reconstruction with TRAM flaps: normal and abnormal appearances at CT. Radiographics 19:1593-1603

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Fig. 4: Deep inferior epigastric perforator (DIEP) flap scheme. This procedure involves microdissection of the perforator vessels from the deep inferior epigastric artery and anastomosis with the internal mammary vessels. The flap does not contain abdominal wall muscle. © Dialani V et al. (2012) MR imaging of the reconstructed breast: what the radiologist needs to know. Insights Imaging 3:201-213

Fig. 5: Deep inferior epigastric artery (DIEA). Coronal maximum-intensity projection (MIP) image shows the origin of the deep inferior epigastric arteries (arrows) from the external iliac artery, superior to the inguinal ligament. In this case, a single trunk is seen on both sides. © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

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Fig. 6: Deep inferior epigastric perforator (arrow) with some favorable characteristics: good vessel caliber (~ 3 mm) arising 19 mm lateral to the umbilicus. Vessel caliber > 2 mm, and location less than 3 cm lateral and less than 3 cm inferior to the umbilical fold are considered favorable anatomic variables. However, a medial direction after perforating the rectus sheath is preferable (in this case, the vessel courses laterally). © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

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Fig. 7: Deep inferior epigastric perforators. Sagittal reformatted MIP image shows two perforators. One is perforating the rectus sheath above the umbilicus (dashed arrow). The other one, more inferior has a large caliber and a smooth and short (< 3 cm) intramuscular course (arrow). © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

Fig. 8: Unfavorable anatomy of a perforator. This axial MIP reformatted image shows deep inferior epigastric perforator artery with a short but tortuous intramuscular segment (arrow), making it unsuitable for microdissection. © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

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Fig. 9: Normal mammographic (a, b) and ultrasonographic (c) appearance of a breast reconstruction with a latissimus dorsi myocutaneous flap. At mammography, the breast is predominantly fatty, with a soft tissue density seen posteriorly, representing the muscle. This is best appreciated in the MLO view (arrowheads). At ultrasound, hypoechoic fat with hyperechoic septa is noted anteriorly, with the muscle posteriorly. Also note de silicone implant, a common feature of the latissimus dorsi flap due to the usually insufficient amount of tissue harvested. The silicone implant is radiopaque at mammography and completely anechoic at ultrasound (asterisk). © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

Fig. 10: Normal imaging appearance of a DIEP flap. The right breast is almost enterly fatty in concordance with the normal imaging features of a DIEP flap as seen on the mammographic craniocaudal (a) and mediolateral oblique views (MLO, b). Note some surgical clips in the posterior region only seen in the MLO view (arrows). This is a normal Page 16 of 28

and common finding. The normal ultrasonographic features of a DIEP flap are illustrated in image c. © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

Fig. 11: Latissimus dorsi myocutaneous flap: appearance in MR imaging. Axial contrastenhanced T1 weighted image with fat saturation depicts the right latissimus dorsi muscle (arrow) flipped anteriorly and inferiorly along with its accompanying fat. Compare with the normal left breast. © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

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Fig. 12: TRAM flap as seen on CT. The left breast is almost enterily fatty. Coronal MIP reformatted images shows normal left rectus muscle and absent right rectus abdominis muscle (asterisk), which is "tunneled" to the contralateral mastectomy site. Note the lipomatous infiltration of the muscle, a very common finding (arrow). © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

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Fig. 13: Normal DIEP flap at MR imaging. T1 weighted contrast-enhanced MIP image shows the predominantly fatty right breast and depicts the vascular anastomosis between the right internal mammary vessels and the vascular pedicle dissected from the flap (arrow). Compare with the normal left breast. © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

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Fig. 14: Three mammograms from three different patients who underwent TRAM flap reconstruction depicting the typical imaging appearance of fat necrosis on mammography, consisting of variable sized lucent-center cysts with smooth peripheral calcifiications (arrows). © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

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Fig. 15: Fat necrosis presenting as pleomorphic calcifications in a reconstructed breast with the TRAM flap technique. Craniocaudal (a) and MLO (b) views of the right breast show peripherally located clusters of pleomorphic calcifications (notably in the upper outer quadrant). The peripheral location is common in fat necrosis on autologous tissuebased flaps due to the poor vascularization of these areas. © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

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Fig. 16: Unusual presentation of fat necrosis. Craniocaudal (a) and MLO (b) views of a TRAM flap reconstruction shows an oval circumscribed mass on the lower inner quadrant (BI-RADS category: 4b). Fat necrosis was proven at biopsy. © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

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Fig. 17: Fat necrosis imaging findings on ultrasonography. At US, fat necrosis can appear as cysts with (a, c) or without (b) echogenic internal debris. Compare the ultrasonographic appearance with the mammographic findings in figure 14. © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

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Fig. 18: Ultrasound image from the same patient as in figure 16, showing a circumscribed oval nodule, parallel to the skin surface, measuring 11 mm. Note the faint posterior acoustic enhancement (arrowheads). BI-RADS category 4b. This was biopsy proven fat necrosis after breast reconstruction with a TRAM flap. © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

Fig. 19: Fat necrosis at MR imaging (same patient as figures 16 and 18). There is a circumscribed mass on the left lower inner quadrant, which is hyperintense on T1W non fat-suppressed image (a), and hypointense on T1W fat-supressed contrast-enhanced sequence and short-tau inversion recovery (STIR, c) pulse sequence. This appearance (following the fat signal in all sequences) is characteristic of fat necrosis. The mass shows early peripheral rim-like enhancement, without washout (not shown) consistent with fat necrosis. © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

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Fig. 20: This ultrasound evaluation in the first post-operative days after DIEP flap surgery shows thickening and edematous change of the skin and subcutaneous tissue of the flap, but no discernible fluid collections were noted. © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

Fig. 21: Transverse (a) and longitudinal (b) images showing a complex fluid collection measuring 4 cm in the post-operative period after TRAM flap reconstruction. This was surgically drained and proved to be an hematoma. © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

Fig. 22: Breast cancer recurrence. This 46 year-old woman performed a skin sparing mastectomy for invasive cancer followed by reconstruction with a DIEP flap. She presented with a palpable subcutaneous nodule 2 years later. At ultrasound (a), a 5 mm solid, hypoechoic, "taller than wide" nodule with irregular borders was noted under the mastectomy scar. BI-RADS category 5 was assigned. At MRI, the lesion shows mild hyperintensity in STIR images (arrow in b). Fat-saturated early post-contrast T1 weighted image (arrow in c) clearly depicts the nodule. Invasive carcinoma was confirmed histologically. © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

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Fig. 23: Breast cancer recurrence in a TRAM flap. Ultrasonography shows a solid hypoechoic mass with irregular borders. BI-RADS category 4c was assigned. Early contrast-enhanced fat-saturated T1 weighted image (b) shows an avidly enhancing irregular mass in the left axilary fold (arrow). This was the same patient of figures 16, 18 and 19. The mass was barely visible at mammography, but clearly depicted on ultrasound and MRI. © Radiology, Centro Hospitalar de São João, Hospital de São João - Porto/PT

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Conclusion Breast reconstruction is an important component of breast cancer care. The use of autologous tissue flaps for breast reconstruction has gained popularity due to recent advances in microvascular surgery. These procedures provide superior esthetic results, a more natural texture of the reconstructed breast and overall better patient satisfaction. Breast radiologists should be familiar with the described surgical techniques as well as with the normal and abnormal imaging features following breast reconstruction.

Personal information Department of Radiology Hospital de São João Centro Hospitalar de São João, EPE Porto, Portugal Head: Isabel Ramos, MD, PhD

References Pinel-Giroux FM et al. Breast reconstruction: review of surgical methods and spectrum of imaging findings. Radiographics, 2013 Scaranelo AM, Lord B, Eiada R, Hofer S. Imaging approaches and findings in the reconstructed breast: a pictorial essay. Canadian Association of Radiologists Journal, 2011 LePage MA, Kazerooni EA, Helvie MA, Wilkins EG. Breast reconstruction with TRAM flaps: normal and abnormal appearances at CT. Radiographics, 1999 Dialani V, Lai KC, Slanetz PJ. MR imaging of the reconstructed breast: what the radiologist needs to know. Insights Imaging, 2012

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Kim SM, Park JM. Mammographic and ultrasonographic features after autogenous myocutaneous flap reconstruction mammoplasty. J Ultrasound Med, 2004 Karunanithy N, Rose V, Lim AKP, Mitchell A. CT angiography of inferior epigastric and gluteal perforating arteries before free flap breast reconstruction. Radiographics, 2011 Hogge J, Zuurbier RA, de Paredes ES. Mammography of autologous myocutaneous flaps. Radiographics, 1999

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