Multifeature analysis of Gd-enhanced MR images of breast lesions.

The objective of this study was to determine whether linear discriminant analysis of different independent features of MR images of breast lesions can increase the sensitivity and specificity of this technique. For MR images of 23 benign and 20 malignant breast lesions, three independent classes of features, including characteristics of Gd-DTPA-uptake curve, boundary, and texture were evaluated. The three classes included five, four and eight features each, respectively. Discriminant analysis was applied both within and across the three classes, to find the best combination of features yielding the highest classification accuracy. The highest specificity and sensitivity of the different classes considered independently were as follows: Gd-uptake curves, 83% and 70%; boundary features, 86% and 70%; and texture, 70% and 75%, respectively. A combination of one feature each from the first two classes and age yielded a specificity of 79% and sensitivity of 90%, whereas highest figures of 93% and 95%, respectively, were obtained when a total of 10 features were combined across different classes. Statistical analysis of different independent classes of features in MR images of breast lesions can improve the classification accuracy of this technique significantly.

Residual silicone detection using MRI following previous breast implant removal: case reports.

The current controversy surrounding the safety of silicone gel breast implants has resulted in an increasing number being removed. Although previous reports have suggested that remnants of the implant capsule are reabsorbed after explantation surgery, the persistence of the capsule in fact may be associated with implant fragments and silicone gel leakage. In this study we have used magnetic resonance imaging (MRI) to identify residual silicone gel and silicone granulomas following the removal of silicone gel breast implants. Four representative clinical case reports are presented. These patients, who had residual silicone present in their bodies, presented to us with breast pain, palpable masses, or abnormal calcific mass densities apparent on a mammogram. High-resolution MRI images were found to be helpful in identifying local and remote collections of silicone gel, silicone granulomas, and residual capsules that were incompletely removed from previous explantation surgery. MRI breast images demonstrated high resolution and provided the accurate anatomical locations of residual silicone gel and silicone granulomas in all the regions of breast parenchyma, chest wall muscles, and axillae. Patients with persistent local symptoms following explantation surgery may benefit from an evaluation of the breast using MRI.

Evaluation of autogenous tissue breast reconstruction using MRI.

Recent controversy encountered with silicone breast implants has increased the use of autogenous tissue for breast reconstruction following mastectomy. Surveillance of patients who have undergone autogenous tissue reconstruction is important in the evaluation of recurrent or new cancer. Magnetic resonance imaging (MRI) has proven to be a useful technique in the delineation of soft tissues and provides excellent resolution. Recently, MRI has been reported to be a valuable diagnostic imaging modality for the evaluation of augmented breast implant patients with regard to implant rupture detection, silicone granuloma identification, and silicone gel migration delineation. In this study, various autologous tissue donor sites currently available for breast reconstruction were imaged by MRI. The following donor flaps were included: fleur-de-lis, TRAM, gluteal, and tensor fasciae latae. A total of 10 clinical cases were investigated. The anatomic basis of each flap type is illustrated, and various tissue components of flap tissue (skin, fat, and muscle) are demonstrated on MRI scan. Anatomic knowledge of autogenous tissue types and MRI appearance of the flap-breast-chest-wall interface are critical in the surveillance and follow-up of breast cancer patients.

Silicone implant rupture diagnosis using computed tomography: a case report and experience with 22 surgically removed implants.

Silicone elastomer shell rupture is a complication of silicone implants. To date, the rate of implant rupture has not been well documented. Magnetic resonance imaging and sonography are noninvasive breast implant imaging modalities that have been shown to be useful in evaluating the integrity of implants. We present a case of rupture detection using a follow-up computed tomographic (CT) scan of a breast cancer patient, which prompted us to use CT scans to evaluate explants of patients undergoing implant removal surgery. The purpose of the investigation was to evaluate the effectiveness of CT scan in detecting rupture. CT scan was performed on 22 explants with intact capsules, for which 17 ruptures were confirmed: 16 true-positive ruptures, 5 true-negative ruptures, O false-positive ruptures, and 1 false-negative rupture were identified. CT scan was shown to be highly sensitive and specific in rupture detection, comparable to magnetic resonance imaging. Although CT scans are consistently reliable, patients are exposed to ionizing radiation; therefore, it is not recommended for patients with augmentation mammoplasty. This study characterizes the appearance of implant rupture on CT scan, which may be useful in evaluating breast cancer patients reconstructed with silicone implants.

MR imaging of breast implants.

MR imaging has proved to be an excellent imaging modality in locating free silicone and evaluating an implant for rupture, with a sensitivity of approximately 94% and specificity of 97%. Silicone has a unique MR resonance frequency and long T1 and T2 relaxation times, which allows several MR sequences to provide excellent diagnostic images. The most commonly used sequences include T2-weighted, STIR, and chemical shift imaging (Figs. 3, 13, and 14). The T2-weighted and STIR sequences are often used in conjunction with chemical water suppression. The most reliable findings on MR images for detection of implant rupture include identification of the collapsed implant shell (linguine sign) and free silicone within the breast parenchyma.

Mammographically detected recurrent nonpalpable carcinoma developing in a transverse rectus abdominus myocutaneous flap. A case report.

BACKGROUND: Breast reconstruction is performed with increasing frequency and has become important in the treatment of mastectomy patients. METHODS: The development of recurrent carcinoma after a mastectomy and transverse rectus abdominus myocutaneous (TRAM) flap procedure is described. RESULTS: The lesion was nonpalpable and was detected by mammography. CONCLUSION: This case raises questions about the practice of not performing postreconstruction mammography for detection of local recurrence after mastectomy.

Comparative silicone breast implant evaluation using mammography, sonography, and magnetic resonance imaging: experience with 59 implants.

With the current controversy regarding the safety of silicone implants, the detection and evaluation of implant rupture are causing concern for both plastic surgeons and patients. Our study obtained comparative value analysis of mammography, sonography, and magnetic resonance imaging (MRI) in the detection of silicone implant rupture. Twenty-nine symptomatic patients (total of 59 silicone implants) were entered into the study. Intraoperative findings revealed 21 ruptured implants (36 percent). During physical examination, a positive "squeeze test" was highly suggestive of implant rupture. Mammograms were obtained of 51 implants (sensitivity 11 percent, specificity 89 percent). Sonography was performed on 57 implants (sensitivity 70 percent, specificity 92 percent). MRI was performed on 55 implants (sensitivity 81 percent, specificity 92 percent). Sonographically, implant rupture is demonstrated by the "stepladder sign." Double-lumen implants may appear as false-positive results for rupture on sonography. On MRI, the "linguine sign" represents disrupted fragments of a ruptured implant. The most reliable imaging modality for implant rupture detection is MRI, followed by sonogram. Mammogram is the least reliable. Our study supports the clinical indication and diagnostic value of sonogram and MRI in the evaluation of symptomatic breast implant patients.

Linguine sign at MR imaging: does it represent the collapsed silicone implant shell?

One intact and one ruptured single-lumen implant were surgically placed in a rabbit. Magnetic resonance (MR) imaging was performed before and after surgical removal, and the ruptured implant was imaged after removal of the implant shell. Multiple curvilinear hypointense lines (linguine sign) were present in the MR images of the ruptured implant and of the implant shell alone immersed in saline solution but not in the image of the free silicone. The collapsed implant shell in a ruptured silicone implant does cause the linguine sign.

Silicone breast implant rupture: comparison between three-point Dixon and fast spin-echo MR imaging.

OBJECTIVE: This study was designed to compare the three-point Dixon technique with our present MR protocol incorporating T2-weighted fast spin echo and fast spin echo with water suppression to detect ruptured silicone breast implants. SUBJECTS AND METHODS: Eighty-two symptomatic women with silicone breast implants were examined with both the three-point Dixon technique and fast spin-echo MR sequences. Of these patients, 41 had surgery to remove their implants. Four radiologists reviewed the images from only those patients who had surgery and graded each for rupture by using a scale of 1-5. Receiver-operating-characteristic analysis was performed. RESULTS: Of 81 implants removed, 18 were ruptured. Silicone implant ruptures were identified more frequently on the fast spin-echo sequence than on the three-point Dixon sequence, with areas under the ROC curves of .95 and .84, respectively. Although the difference was not statistically significant, the sensitivity for detecting silicone implant rupture was 89% for the fast spin-echo sequence and 61% for the three-point Dixon sequence. The specificity was 97% for both sequences. CONCLUSION: Silicone implant ruptures were detected more frequently with fast spin-echo MR sequences than with the three-point Dixon technique, although the difference was not significant. The greater spatial resolution used for the fast spin-echo sequence partially accounts for the difference in detection of implant ruptures in this study.

Role of MRI in the evaluation of ambiguous genitalia.

Diagnostic accuracy of magnetic resonance imaging (MRI) interpretation was assessed prospectively in patients with ambiguous genitalia or intersex problems. MRI depiction of the uterus was possible in 93%, the vagina in 95%, the penis in 100%, the testis in 88%, and the ovary in 74% of patients. The strength of MRI lies in the multiplanar capability and tissue characterization by means of T1- and T2-weighted sequences. MRI contributes to accurate morphologic evaluation of müllerian duct structures, the gonads, and the development of the phallus, all of which are essential for appropriate gender assignment and planning of surgical reconstruction.

Silicone breast implant ruptures in an animal model: comparison of mammography, MR imaging, US, and CT.

PURPOSE: To determine the most accurate imaging modality for detection of silicone implant ruptures. MATERIALS AND METHODS: Forty single-lumen silicone implants were surgically placed in 20 rabbits. Each rabbit received one intact and one ruptured implant and was examined with mammography, magnetic resonance (MR) imaging, ultrasound (US), and computed tomography (CT). Five radiologists reviewed all images in a random fashion and graded each for rupture. The radiologist who performed US also graded her impression during examination with US. Receiver operating characteristic (ROC) analysis was performed. RESULTS: MR imaging and CT were the most accurate modalities in detection of implant ruptures, with areas under the ROC curves (Az) of .95 and .91. Mammography and US were statistically significantly inferior, with Az of .77 for each (P < .05). CONCLUSION: MR imaging and CT are statistically more accurate than US and mammography for detection of intracapsular silicone implant ruptures when only the images are reviewed.

Silicone breast implants: US evaluation.

PURPOSE: To determine the value of breast ultrasonography (US) in the assessment of silicone breast implants for rupture. MATERIALS AND METHODS: Seventy-four women with local or systemic symptoms related to silicone implants underwent breast US. Of these, 28 underwent surgical removal of the implants. RESULTS: Of 57 implants removed, 37 were intact. The most reliable sign of an intact implant was an anechoic interior, although reverberation artifact and radical folds could be seen. Of 20 ruptured implants, 16 were intracapsular and four were extracapsular ruptures. The most reliable US sign of rupture was echogenic, horizontal ("stepladder") lines (14 of 20 ruptures). Two of the four extracapsular ruptures were accurately identified as echogenic nodules outside the implant; two were false-negative findings. Three intracapsular ruptures identified at US were false-positive; six were false-negative. Overall sensitivity for rupture was 70%, specificity was 92%, positive predictive value was 82%, and negative predictive value was 85%. CONCLUSION: Breast US is capable of depicting intracapsular and extracapsular rupture of breast implants.

MR imaging of the breast in patients with silicone-gel implants: spectrum of findings.

Because of recent concerns about the potential dangers of rupture and leakage of silicone-gel implants, radiologists are often requested to evaluate the integrity of normal breast implants. Clinical studies suggest that MR imaging can accurately depict implant rupture. The purpose of this pictorial essay is to illustrate the spectrum of MR appearances of breasts in patients with silicone-gel implants. Types of prostheses range from the more common single-lumen silicone-gel implants to the rare foam-filled implants. Recognition of the variable appearance of intact implants is emphasized in order to distinguish these from intracapsular or extracapsular ruptures. Finally, we briefly review various investigational MR sequences designed to improve the evaluation of the integrity of silicone-gel implants and the localization of free silicone. This article is based on our experience in performing MR imaging in more than 350 patients with breast implants. In more than 50% of these patients, the MR imaging findings have been correlated with surgical and pathologic findings.

Definitive diagnosis of breast implant rupture using magnetic resonance imaging.

Breast implant rupture is an important complication of augmented and reconstructed breasts. Although several techniques such as mammography, xeromammography, ultrasound, thermography, and computed tomographic (CT) scanning have been proven to be useful to detect implant rupture, they have several disadvantages and lack specificity. In the current study, we have established magnetic resonance imaging (MRI) as a definitive, reliable, and reproducible technique to diagnose both intracapsular and extracapsular ruptures. The study was conducted in 100 symptomatic patients. Our imaging parameters were able to identify ruptures in implants with silicone shells. All the ruptures showed the presence of wavy lines, free-floating silicone shell within the gel ("free-floating loose-thread sign" or "linguine sign"). We had a 3.75 percent incidence of false-positive and false-negative results. The sensitivity for detection of silicone implant rupture was 76 percent, with a specificity of 97 percent. In addition, we also were able to identify the artifacts that may interfere with the definitive diagnosis of implant rupture.

MR imaging of silicone breast implants: comparison of different coil arrays.

To determine the optimal coil and patient position for magnetic resonance imaging of patients with silicone breast implants, images obtained with body, circular surface, flexible, single shoulder, and dual shoulder coils in various numbers of patients were compared with regard to signal-to-noise ratio (S/N), decay of signal intensity, resolution, and key area coverage. Images obtained with the dual shoulder coil and prone position, with a customized positioning device, gave the best S/N, resolution, and coverage of the breasts and axillae.

Silicone breast implants in vivo: MR imaging.

This study was designed to evaluate pulse sequences and patient positioning for MR imaging of silicone breast implants in patients. One hundred forty-three patients (281 silicone implants) underwent imaging over a 21-month period. The combination of a T2-weighted fast spin echo technique (SE), T2-weighted fast SE with water suppression, and T1-weighted SE with fat suppression is recommended to reliably differentiate silicone from other breast tissues and to identify intracapsular and extracapsular ruptures or leaks. Seventy of the 143 patients underwent removal of their silicone implants. The sensitivity for detection of silicone implant rupture was 76%, with a specificity of 97%. Positioning the patient prone improved image quality.

Is there a role for diskography in the era of magnetic resonance imaging? Prospective correlation and quantitative analysis of computed tomography-diskography, magnetic resonance imaging, and surgical findings.

We herein report the results of a prospective study to define the role of diskography in the diagnosis of low back pain in an emerging era of magnetic resonance imaging (MRI). The study involved 32 patients (78 disks) with a clinical diagnosis of lumbar disk herniation; all were studied by computed tomography-diskography (CT-D), and 25 (51 disks) were also examined using MRI. The disks were graded on these studies according to a staging scheme modified from Modic. Ten of the patients (13 disks) having both CT-D and MRI underwent exploratory surgery, and the staging at surgery served as the standard against which the evaluative studies were judged. Surgical staging was compatible with the CT-D and MRI results in five disks, while in another five disks it was compatible only with the CT-D results. In the remaining three disks, both CT-D and MRI misidentified the stages. In six disks, CT-D more accurately defined the stage of disease than did MRI, whereas MRI was more precise than CT-D in only one disk. While having documented the value of CT-D as a source of information, particularly when surgery is contemplated, and as an effective means of staging disk herniation, we recommend MRI as the ideal screening test for lumbar radiculopathy and low back pain, reserving diskography for problematic cases.