MRI Appearance of Tumor Recurrence in Myocutaneous Flap Reconstruction After Mastectomy

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1 Women s Imaging Clinical Perspective Peng et al. MRI fter reast Reconstruction Women s Imaging Clinical Perspective WOMEN S IMGING Chenjing Peng 1,2 C. elinda Chang 1 Hilda H. Tso 3 Christopher I. Flowers 1 Nola M. Hylton 1 onnie N. Joe 1 Peng C, Chang C, Tso HH, Flowers CI, Hylton NM, Joe N Keywords: breast cancer, breast reconstruction, flap, recurrence, screening DOI: /JR Received July 8, 2010; accepted after revision September 13, Department of Radiology and iomedical Imaging, University of California, San Francisco, Mount Zion Medical Center, 1600 Divisadero St, Rm C-250, ox 1667, San Francisco, C ddress correspondence to C.. Chang (elinda.chang@radiology.ucsf.edu). 2 Present address: Solihull, West Midlands, UK. 3 Present address: Department of Women s Imaging Center, JPS Health Center for Women, Fort Worth, TX. WE This is a Web exclusive article. JR 2011; 196:W471 W X/11/1964 W471 merican Roentgen Ray Society MRI ppearance of Tumor Recurrence in Myocutaneous Flap Reconstruction fter Mastectomy OJECTIVE. The purpose of this perspective is to describe the role of breast MRI in the detection of local tumor recurrence in myocutaneous flap reconstructions and in the evaluation of extent of disease. CONCLUSION. Recognizing the MRI appearance of tumor recurrence in breast myocutaneous flap reconstructions is important for early detection of recurrence and in the evaluation of extent of disease to guide clinical management. ilateral breast MRI for high-risk cancer screening of the native breast is a unique opportunity to detect recurrence in the reconstructed breast before it is clinically apparent. We describe a range of MRI appearances of breast cancer recurrence in patients with myocutaneous flap reconstructions. M yocutaneous flap reconstruction of the breast after mastectomy for breast cancer includes the use of the transverse rectus abdominis myocutaneous (TRM) flap, latissimus dorsi flap, and the recently developed deep inferior epigastric perforator flap. TRM flap reconstruction is the most commonly used and has been associated with a low (2 4%) incidence of local tumor recurrence in the reconstructed breast [1, 2]. Numerous cases of myocutaneous flap recurrence have been described, but there is still no consensus on the best method for detecting recurrence [3 5]. In patients with symptoms of recurrence, mammography, ultrasound, and MRI have proved effective adjuncts to clinical diagnosis [6 8]. There is controversy, however, over the cost-effectiveness of screening for recurrence in patients who do not have symptoms. Screening mammography depicts nonpalpable cancer recurrence in the reconstructed breast [9], but it is not recommended for all patients because of the low overall detection rate and because visualization of nonspecific benign changes in the flap can lead to invasive investigative procedures [10]. These patients often undergo diagnostic imaging because of various clinical concerns. MRI is superior for visualization of the normal TRM flap appearance and for differentiating benign from malignant changes [8, 11]. With more facilities performing bilateral breast MRI for high-risk cancer screen- ing of the contralateral native breast, the reconstructed breast is also imaged as part of the MRI screening examination. s a result, there is potential for early detection of local tumor recurrence in the reconstructed breast if features of recurrent tumor are recognized at MRI before clinical presentation. MRI also can yield critical information about the extent of disease, which guides clinical management. It is important to note that routine screening of women with a personal history of breast cancer is not currently recommended by the merican Cancer Society unless additional risk factors are present [12]. enign changes in the myocutaneous flap reconstruction are commonly seen on MR images, but relatively few appearances of cancer recurrence have been described [8, 11]. Our purpose is to describe the MRI appearance of a range of local tumor recurrences in myocutaneous flap reconstructions. MRI cquisition MRI was performed with a 1.5-T imager (Signa, GE Healthcare). Contrast-enhanced MRI of the breast was performed by acquisition of data at three time points: one unenhanced acquisition followed by two contrast-enhanced acquisitions in two consecutive 3- to 5-minute intervals. 3D fast gradient-recalled echo imaging sequence was performed to produce high-spatial-resolution fat-suppressed images with full coverage of both breasts in the axial plane. The imaging parameters were W471

2 Peng et al. Fig year-old woman undergoing high-risk screening for breast cancer in native breast. Contrastenhanced axial T1-weighted fat-suppressed MR image shows normal transverse rectus abdominis myocutaneous (TRM) flap reconstruction in right breast compared with native left breast. Glandular breast tissue (arrowheads) is evident in native left breast, and reconstructed breast consists entirely of adipose tissue with no evidence of residual glandular mammary tissue. Delineation line outlining contact zone between TRM flap and native tissue appears as line of intermediate signal intensity (arrow) parallel to breast contour. as follows: TR/TE, 9/4.4; flip angle, 10 ; number of signals acquired, 1; acquisition matrix, ; section thickness, 2 mm. The field of view was cm 2, depending on patient size. The contrast agent gadopentetate dimeglumine (Magnevist, ayer Schering Pharma) was administered IV at a dose of 0.1 mmol/kg body weight with an MRI-compatible remote control power injector (Spectris, Medrad) at a rate of 1.2 ml/s. The contrast injection was followed by a 10-mL saline flush administered at the same flow rate. The central phaseencoding lines of each data set were acquired halfway through the acquisition, yielding effective contrast-enhanced sample times of seconds and seconds. Common problems in MRI of reconstructed breasts are failure of fat suppression and inhomogeneous fat suppression. Fat normally appears as an area of high signal intensity on T1-weighted images, making identification of enhancing lesions in the breast difficult against a background of high-signal-intensity fat. Therefore, fat suppression is routinely performed to increase lesion conspicuity and facilitate lesion identification. However, various factors, including asymmetry, can cause magnetic field inhomogeneity, which results in poor fat suppression. Field inhomogeneity can be improved by adjustment of the shim gradients and ensuring that shim volumes adequately cover the breast tissue. In addition, center frequency should be adjusted to the center of the water peak for optimal fat suppression. If fat suppression remains a problem, images may be obtained without fat suppression while the patient is instructed to remain very still. Subtraction images can then be used for interpretation. ppearance of Flap Reconstructions on MR Images The normal MRI appearance of a myocutaneous flap reconstruction includes changes in tissue composition, most notably replacement of glandular breast tissue by adipose tissue, and the presence of a line of intermediate signal intensity that separates the native tissue from the flap reconstruction (Fig. 1). enign lesions associated with reconstructive surgery are common and therefore must be differentiated from malignant changes. On MR images, features of fat necrosis, skin thickening, seroma, and hematoma can be visualized that may morphologically resemble those of recurrent tumors [8]. The variable appearance of fat necrosis on MR images includes slow, gradual, rapid, and washout enhancement kinetics. reas of signal void may be seen if calcifications are present [13]. ecause fat necrosis can mimic carcinoma, tissue sampling may be necessary. Correlation with mammographic findings is often helpful for definitive diagnosis of fat necrosis. Some enhancement also may be seen in benign changes, especially if the patient has recently undergone radiotherapy. Incidental Detection of Recurrence in Reconstructed reast at Screening MRI lthough MRI evaluation for possible recurrence in a reconstructed breast has been used predominantly in the care of patients with symptoms [8], in a study of screening MRI of 41 patients with myocutaneous flap reconstructions [14], the investigators identified local recurrence before it was clinically apparent in one patient who had undergone latissimus dorsi flap reconstruction. Dynamic contrast uptake was seen in the residual mammary tissue of the reconstructed breast. We also have seen unsuspected recurrences in the reconstructed breast during screening MRI of the contralateral native breast. The low incidence of recurrence in reconstructed breasts and low detection rates with both mammography and MRI have not warranted routine screening of patients who do not have symptoms [10, 14]. However, the increasing use of axial breast MRI to screen for cancer of the contralateral breast allows viewing of the reconstructed breast alongside the native breast. This situation affords an opportunity for detection of local recurrence before clinical presentation. Recurrence in the reconstructed breast can occur at the contact zone between the flap reconstruction and native tissue, presenting as a mass of intermediate T1 signal intensity that has rapid and heterogeneous enhancement after administration of a gadolinium contrast agent (Fig. 2). The high signal intensity of mucinous carcinoma on T2-weighted images can be mistaken for fat necrosis or fluid [15]. In the patient in Figure 1, the mass was believed to represent fat necrosis at clinical examination [8, 11]. However, rapid heterogeneous enhancement on T1-weighted images confirmed the solid nature of the lesion. mammogram also can be obtained to exclude fat necrosis [13, 16]. Most recurrent tumors develop in the skin or subcutaneous tissue of the flap and are detected by clinical palpation [1, 2]. Conversely, lesions can recur in a posterior location in the breast and because of the posterior location would not be clinically palpable and not be detected with mammography (Fig. 3). Figure 3 shows recurrent invasive ductal carcinoma, which can appear as an irregular focal mass or, less commonly, a well-circumscribed circular lesion [11]. Evaluation of the Extent of Recurrent Disease With MRI of the Reconstructed reast For some patients, MRI after diagnostic mammography is needed to gain information about the extent of disease recurrence. This examination is especially pertinent in the care W472

3 MRI fter reast Reconstruction of patients who have undergone reconstructive surgery, in which the normal breast architecture is disrupted, making mammographic interpretation difficult. lthough most recurrences have been reported within 5 years of reconstruction [1, 2], delayed local recurrence also can occur. Nine years after undergoing mastectomy and TRM Fig year-old woman 2 years after initial diagnosis of mucinous carcinoma who has incidental finding of local recurrence in deep inferior epigastric perforator flap of reconstructed right breast at bilateral screening MRI., Unenhanced axial T1-weighted fat-suppressed image of right breast shows round 1.2-cm-diameter mass (arrow) of intermediate signal intensity in lower inner quadrant at contact zone between flap reconstruction and native tissue., Contrast-enhanced axial T1-weighted fat-suppressed image shows heterogeneous enhancement of mass (arrow), which exhibited persistent enhancement on later contrast-enhanced images. C, xial fat-suppressed T2-weighted spin-echo image shows high-signal-intensity mass (arrow) consistent with mucinous carcinoma. C D Fig year-old woman 4 years after initial diagnosis of invasive ductal carcinoma who has incidental finding of local recurrence in transverse rectus abdominis myocutaneous flap of reconstructed left breast at bilateral screening., Contrast-enhanced axial fat-suppressed T1- weighted MR image shows small nodular areas of enhancement next to muscle at 11 o clock position, largest area measuring 8 mm (arrow)., xial subtracted MR image shows enhancement of masses (arrow). C, Mediolateral oblique mammogram shows mass (arrow) in posterior left upper outer region of breast immediately below surgical clips, corresponding to finding in. D, Ultrasound image shows two solid hypoechoic masses (arrows) in left upper outer region of breast corresponding to nodular areas of enhancement in. flap reconstruction, a 64-year-old woman was found to have suspicious mammographic findings. ecause of diagnostic and anatomic uncertainty, MRI was performed and showed a heterogeneously enhancing spiculated mass in the contact zone between the residual breast tissue and the flap reconstruction (Fig. 4). The results of pathologic examination confirmed the presence of recurrent lobular carcinoma. nother use of MRI is assessment of lobular carcinoma, which is known for its extensive growth pattern that progressively replaces the surrounding breast parenchyma [11]. Lobular carcinoma does not typically induce calcifications and can therefore go undetected with mammography. n 80-year-old patient with recurrent lobular carcinoma experienced symptoms 3 years after undergoing latissimus dorsi flap reconstruction, despite having undergone mastectomy for the original cancer 15 years previously and having been disease free. Figure 5 shows the extensive tumor invasion originating within the flap reconstruction. The patient had presented with increasing lumps in the reconstructed breast and edema in the right arm. MRI revealed dramatic and extensive enhancement representing diffuse tumor infiltration into the surrounding tissue that had not been detected on previous mammograms. MRI C W473

4 Peng et al. depicted chest wall invasion not visualized with mammography (Fig. 5C). Discussion MRI of the breast depicts asymptomatic cancer recurrence in the reconstructed breast and is useful for evaluation of the extent of disease. With the increasing use of bilateral breast MRI to screen the native breast for cancer, the reconstructed side is included in the field of view and should not be overlooked under the assumption that there is no remaining breast tissue. Numerous cases of myocutaneous flap recurrence have been reported. MRI of the breast has potential in the detection of cancer recurrence in the reconstructed breast before it is clinically apparent, especially if lesions are located more posteriorly or if superficial lesions are clinically misinterpreted as fat necrosis. Patients with recurrence in the chest wall are more likely to have systemic symptoms, have metastatic disease, and have a poorer prognosis [1, 2], and early detection in the care of these patients may improve prognosis. Our experience has been that the appearance of tumor Fig year-old woman 9 years after initial diagnosis of lobular carcinoma who has MRI finding suggesting local recurrence in transverse rectus abdominis myocutaneous flap of reconstructed right breast., Unenhanced sagittal T1-weighted fat-suppressed image shows 9-mm spiculated mass in upper inner quadrant of right breast., Contrast-enhanced T1-weighted fatsuppressed image shows rapid heterogeneous initial enhancement of mass (arrow). Persistent enhancement was seen on later images. C Fig year-old woman 3 years after reconstructive surgery with evidence of extensive lobular carcinoma in latissimus dorsi flap of reconstructed right breast. Initial diagnosis was ductal carcinoma in situ, which had been managed with radical modified mastectomy 15 years earlier., Mediolateral oblique mammogram of reconstructed breast shows nonspecific changes of increased density in muscle region (asterisk) and skin thickening (arrow)., T1-weighted fat-suppressed MR image shows intense masslike enhancement (arrowheads) in latissimus dorsi flap of right breast. Uninvolved adjacent muscle (asterisk) without intense enhancement is evident. C, T1-weighted fat-suppressed MR image at level inferior to shows extensive enhancement of muscle with intrathoracic and chest wall invasion (arrowheads). bnormal skin thickening (arrow) also is evident in. recurrence on MR images is often not subtle. Despite the prevalence of benign lesions after reconstructive surgery, enhancing lesions are highly suspicious and should prompt further evaluation and tissue sampling. There are several circumstances in which MRI yields valuable information about the extent of disease in the reconstructed breast that can aid clinical management. MRI sometimes better depicts the reconstructed breast than does mammography and helps in localization and further assessment of the morphologic features and kinetics of suspicious masses. In W474

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