Faculty Bibliography

A rat model has been devised to study the determinants of microvascular anastomotic patency in the setting of diameter discrepancy. Isogeneic interposition grafts of rat inferior vena cava were used to repair a femoral artery defect (diameter ratio 4.5:1). Three methods for compensating for diameter discrepancy were studied. The anastomoses were explored on postoperative days 3, 7, and 14. By 2 weeks, tapered grafts were shown to result in higher patency rates (p < 0.05) compared with nontapered and spatulated grafts. Hemodynamic, histological, and scanning electron microscopic analysis suggested that turbulence caused by large velocity gradients predisposes to thrombosis. This animal model was shown to be sensitive to experimental hemodynamic alterations and may be useful in elucidating the effect of technical or pharmacological manipulations on patency in the setting of vessel diameter discrepancy

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

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

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

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

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

Excellent patency rates are currently established in the use of autogenous veins as interposition vein grafts in microsurgical practice. Allografts may be a viable alternative source of vein grafts. Recent advances in cryobiology have enabled the controlled freezing of tissues with preservation of vital cellular elements. Although several reports have shown the successful use of cryopreserved large-vessel allografts, few have addressed cryopreservation of microvessels (1 to 2 mm in diameter). In this study, the authors have successfully cryopreserved femoral veins in a rat model and transplanted them as interposition vein grafts into arterial defects across major histocompatibility barriers (ACI to Lewis). Short-term patencies (21 days) were determined, and histologic and scanning electron microscopic analysis were performed. Patency of 100 percent was achieved in both fresh control veins and in cryopreserved veins at 21 days

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