Uterine Arterial Embolization With Tris-acryl Gelatin Microspheres

Comparison of Uterine Necrosis After Uterine Artery Embolization with Soluble Gelatin Sponge Particles or Tris-acryl Gelatin Microspheres in Swine

PURPOSE

To compare the recanalization of the uterine arteries and uterine necrosis after uterine artery embolization (UAE) using either soluble gelatin sponge particles (SGS), which dissolve in saline, or tris-acryl gelatin microspheres (MS), which are permanent embolic materials, in swine.

METHODS

Fourteen uteri in seven swine were divided into two groups for embolization with either 500-1000 µm SGS (SGS group) or 500-700 µm MS (MS group) (seven uteri per group). The uterine arteries were embolized using SGS or MS, and angiography was performed to evaluate recanalization of the uterine arteries immediately, 1, 2, 3, 4, 5, and 6 h, and 3 days after embolization. On day 3, the uteri were removed to determine the macroscopic necrosis rate and for histopathologic examination.

RESULTS

In the SGS group, four uterine arteries were completely recanalized, two were partially recanalized, and one was still occluded 5 h after embolization. In contrast, all seven uterine arteries in the MS group were still occluded 6 h after embolization. The complete recanalization rate at 3 days was significantly greater in the SGS group than in the MS group (100.0% vs. 14.3%, respectively; P = .0047). The mean uterine necrosis rate was not significantly different between the SGS and MS groups (15.0 ± 15.7% vs. 26.8 ± 13.3%, respectively; P = .096). The mean smallest arterial diameter containing embolic materials was 48.2 ± 22.0 μm (range 21-109 μm) for SGS and 446.7 ± 107.0 μm (range 352-742 μm) for MS (P < .0001).

CONCLUSION

The uterine arteries recanalized earlier in the SGS group than in the MS group and the uterine necrosis rates were similar in both groups. SGS have the potential for a more distal penetration in comparison with MS.

Advances in Biomaterials and Technologies for Vascular Embolization

Minimally invasive transcatheter embolization is a common nonsurgical procedure in interventional radiology used for the deliberate occlusion of blood vessels for the treatment of diseased or injured vasculature. A wide variety of embolic agents including metallic coils, calibrated microspheres, and liquids are available for clinical practice. Additionally, advances in biomaterials, such as shape-memory foams, biodegradable polymers, and in situ gelling solutions have led to the development of novel preclinical embolic agents. The aim here is to provide a comprehensive overview of current and emerging technologies in endovascular embolization with respect to devices, materials, mechanisms, and design guidelines. Limitations and challenges in embolic materials are also discussed to promote advancement in the field.

Susceptibility weighted MRI after uterine artery embolization for leiomyoma

PURPOSE

To evaluate whether susceptibility-weighted MR imaging (SWI) findings are associated with tumor infarction on contrast-enhanced MRI (CE-MRI) after uterine artery embolization (UAE) for leiomyoma.

METHODS

This was a single institution, retrospective study. Between February 2016 and April 2017, 27 consecutive patients underwent UAE and completed SWI and CE-MRI before and 1 week after UAE. Two blinded readers independently reviewed the MRI of 261 tumors ≥1 cm in all patients. We evaluated the relationship between the hypointense peripheral rim observed on the tumor surface on post-procedural SWI and the infarction rates (≥90%, <90%) of each tumor based on post-procedural CE-MRI. Inter-reader correlation coefficients (ICC) and the sensitivity and specificity of the rim were measured.

RESULTS

Substantial inter-reader agreement was noted in post-procedural SWI interpretations (ICC = 0.681, 95% CI; 0.547, 0.771). The rim was observed in 66.7% (174/261) of tumors by reader 1 and 55.9% (146/261) of tumors by reader 2 on post-procedural SWI. Correlations were observed between the rim and ≥90% tumor infarction by readers 1 and 2 (Spearman's coefficient = 0.474 and 0.438, p < 0.001 and p < 0.001, respectively). The sensitivity and specificity of the rim to tumor infarction were 77.2 and 82.6% (reader 1), and 65.8 and 100% (reader 2), respectively.

CONCLUSIONS

The present study demonstrated that the hypointense peripheral rim was observed on some leiomyomas on SWI immediately after UAE. The rim correlated with tumor infarction on post-procedural CE-MRI. This SWI finding was helpful for evaluating embolic effects on leiomyomas in the acute phase after UAE.

Minimally invasive procedures in the management of uterine fibroids

Uterine fibroids are benign uterine tumors. In women during the reproductive period, uterine fibroids occur in about 25%, whereas after this time, they are observed in more than 40% of women. In the majority of women (about 20-50%), such tumors do not cause discomfort and do not require treatment. Asymptomatic uterine fibroids usually undergo only regular medical control, whereas symptomatic fibroids are an indication for treatment. Current treatment methods include surgical, pharmacological and minimally invasive treatment. Among the current commonly used methods, there are minimally invasive treatment options, which include Uterine Artery Embolization (UAE), Magnetic Resonance Guided Ultrasound Surgery (MRgFUS), MR-guided High Intensity Focused Ultrasound (MR-HIFU) and Laparoscopic Uterine Artery Occlusion (LUAO). The minimally invasive Ultrasound-guided High Intensity Focused Ultrasound method (US-HIFU) is new, but still experimental. The use of MRgFUS/MR-HIFU for the thermoablative treatment of fibroids was approved by the FDA (Food and Drug Administration) in 2004. As a minimally invasive method, it enables preservation of the uterus and eliminates the need for general anesthesia. LUAO is based on the use of the vascular clip, which is placed on the uterine artery at the level of the internal iliac artery. This procedure is performed bilaterally.

The use of UAE in obstetrics and gynecology was first described in 1987 as an effective method in the treatment of hemorrhage, which allows avoiding surgical intervention and enables the uterus to be preserved. An appropriate qualification of patients is crucial for high clinical efficacy and prevention of complications after UAE. The candidates should be women with symptomatic uterine fibroids, without other pathologies within the pelvis, who do not plan to get pregnant in the future.

The variety of uterine fibroids as for the location, size, and symptoms they can evoke, has enforced a very individual approach to each patient, to begin with observation and regular gynecological control, through a number of pharmacological and minimally invasive treatment methods, and ending with the removal of the uterus. It gives the doctors the tools, which, if used properly, can manage uterine fibroids and fulfil the expectations of the patient.

Feasibility, Safety, and Efficacy of Flow-Diverting Stent-Assisted Microsphere Embolization of Fusiform and Sidewall Aneurysms

BACKGROUND

Treatment of wide-necked internal carotid artery aneurysms is frequently associated with incomplete occlusion and high recurrence rates. Furthermore, platinum coils cause strong beam-hardening artifacts, hampering subsequent image analyses.

OBJECTIVE

To assess the feasibility, safety, and efficacy of flow-diverting, stent-assisted microsphere embolization of fusiform and sidewall aneurysms in vitro and in vivo.

METHODS

Using a recirculating pulsatile in vitro flow model, 5 different aneurysm geometries (inner/outer curve, narrow/wide neck, and fusiform) were treated (each n = 1) by flow-diverting stent (FDS) implantation and subsequent embolization through a jailed microcatheter using calibrated microspheres (500-900 μm) larger than the pores of the FDS mesh. Treatment effects were analyzed angiographically and by micro computed tomography. The fluid of the in vitro model was filtered to ensure that no microspheres evaded the aneurysm. The experiment was repeated once in vivo.

RESULTS

In vitro, all 5 aneurysms were safely and completely occluded by FDS-assisted microsphere embolization. Virtually complete aneurysm occlusion was confirmed by angiography and micro computed tomography. No microspheres escaped into the circulation. The experiment was successfully repeated in 1 pig with a sidewall aneurysm generated by vessel occlusion. An embolic protection system placed distally of the FDS in vitro and in vivo (each n = 1) contained no microspheres after the embolization. Thus, no microspheres were lost in the circulation, and the use of an embolic protection system seems feasible to provide additional safety.

CONCLUSION

FDS-assisted microsphere embolization of fusiform and sidewall aneurysms is feasible and yields virtually complete aneurysm occlusion while avoiding coil-associated beam-hardening artifacts.

A novel resorbable embolization microsphere for transient uterine artery occlusion: a comparative study with trisacryl-gelatin microspheres in the sheep model

PURPOSE

To evaluate angiographic recanalization, inflammatory reaction, and uterine damage after sheep uterine artery embolization (UAE) with a novel calibrated resorbable embolization microsphere (REM) and compare the results with control nonresorbable microspheres.

MATERIALS AND METHODS

Six hormonally artificially cycled sheep underwent bilateral UAE until stasis with either REM or trisacryl-gelatin microspheres (TGMS). At 7 days, control angiograms were obtained to assess the residual vascularization at arterial and parenchymal phases. The animals were then sacrificed for analysis of the presence of microspheres, inflammatory foreign body reaction, and surface areas of uterine damage.

RESULTS

Mean volume of microspheres injected per uterine artery (UA) or per animal did not differ between groups. At day 7, the flow was normal for six of six UAs that received embolization with REM versus only three of six UAs with TGMS (P = .0455, χ(2) test). Uterine parenchymography showed no defects in six UAs in the REM group versus five defects in six UAs in the TGMS group (P = .0060, χ(2) test). No REM or residual fragments of microspheres were observed on histologic analysis. TGMS were observed in tissues and accompanied by a mild inflammatory response. Necrosis rates were not significantly different between the two products, either in endometrium (REM 23.5% ± 28.8% [median 8.1%] vs TGMS 21.8% ± 23.7% [median 14.6%]) or in myometrium (REM 8.2% ± 22.7% [median 0.0%] vs TGMS 8.8% ± 20.8% [median 0.9%]). Endometrium alteration rate was lower with REM than with TGMS (39.7% ± 25.7% [median 34%] vs 60.6% ± 27.1% [median 71%]; P = .0060, Mann-Whitney test). Myometrium alteration rates were not significantly different between REM (45.7% ± 37.1% [median 63.0%]) and TGMS (37.8% ± 34.0% [median 19.1%]).

CONCLUSIONS

At 1 week after sheep UAE with REM, the recanalization was complete, the microspheres were completely degraded, and there was no remnant inflammatory response.

Long-term efficacy and quality of life associated with laparoscopic bilateral uterine artery occlusion plus partial resection of symptomatic adenomyosis

OBJECTIVE

To assess the long-term efficacy and quality of life associated with laparoscopic bilateral uterine artery occlusion plus partial resection of symptomatic adenomyosis.

STUDY DESIGN

A total of 182 eligible patients with symptomatic adenomyosis were treated by laparoscopic bilateral uterine artery occlusion plus partial resection of adenomyosis from July 2003 to July 2009. Menstrual blood loss was measured using a pictorial blood loss assessment chart. Pain intensity during menstruation was evaluated on a 10-point visual analog scale (VAS). Health-related quality of life was measured using the WHOQOL-BREF.

RESULTS

A total of 179 patients with 3 years follow-up were enrolled in this retrospective study. No severe complications were noted during the surgical procedure or follow-up period. The mean postoperative dysmenorrhea and menorrhagia scores were significantly improved (all p<0.01) at 3, 12 and 36 months postoperatively, compared with preoperative scores. The volume of the uterus was continuously reduced at 3, 6, 12 and 36 months postoperatively, and had shrunk by 58.3% at 36 months after surgery, compared with the preoperative volume. Notably, only 1.7% (3/179) of patients had received a hysterectomy at 36 months follow-up. In addition, patient's health-related quality of life scores were significantly increased (p<0.01) compared with preoperative scores.

CONCLUSION

Laparoscopic bilateral uterine artery occlusion plus partial resection of symptomatic adenomyosis is effective. There was a very low recurrence rate detected by ultrasound at 36 months.

The role of angiogenic factors in fibroid pathogenesis: potential implications for future therapy

BACKGROUND

It is well established that tumors are dependent on angiogenesis for their growth and survival. Although uterine fibroids are known to be benign tumors with reduced vascularization, recent work demonstrates that the vasculature of fibroids is grossly and microscopically abnormal. Accumulating evidence suggests that angiogenic growth factor dysregulation may be implicated in these vascular and other features of fibroid pathophysiology.

METHODS

Literature searches were performed in PubMed and Google Scholar for articles with content related to angiogenic growth factors and myometrium/leiomyoma. The findings are hereby reviewed and discussed.

RESULTS

Multiple growth factors involved in angiogenesis are differentially expressed in leiomyoma compared with myometrium. These include epidermal growth factor (EGF), heparin-binding-EGF, vascular endothelial growth factor, basic fibroblast growth factor, platelet-derived growth factor, transforming growth factor-β and adrenomedullin. An important paradox is that although leiomyoma tissues are hypoxic, leiomyoma feature down-regulation of key molecular regulators of the hypoxia response. Furthermore, the hypoxic milieu of leiomyoma may contribute to fibroid development and growth. Notably, common treatments for fibroids such as GnRH agonists and uterine artery embolization (UAE) are shown to work at least partly via anti-angiogenic mechanisms.

CONCLUSIONS

Angiogenic growth factors play an important role in mechanisms of fibroid pathophysiology, including abnormal vasculature and fibroid growth and survival. Moreover, the fibroid's abnormal vasculature together with its aberrant hypoxic and angiogenic response may make it especially vulnerable to disruption of its vascular supply, a feature which could be exploited for treatment. Further experimental studies are required in order to gain a better understanding of the growth factors that are involved in normal and pathological myometrial angiogenesis, and to assess the potential of anti-angiogenic treatment strategies for uterine fibroids.

Pathological findings in a case of failed uterine artery embolization for placenta previa

The reported success rate of uterine artery embolization (UAE) for obstetrical hemorrhage is more than 90%. We experienced a case of failed UAE for postpartum hemorrhage, although an embolic particle was found pathologically in the uterine vessels without coagulation. A 42-year-old woman (gravida 7, para 2) with placenta previa had genital bleeding at 35 weeks of gestation, and cesarean section was performed. We immediately added UAE aiming to reduce massive bleeding after the cesarean section, successful embolization of the bilateral uterine arteries and internal iliac arteries were confirmed by angiography regardless the vital sign was recovered with an appropriate amount of transfusion; the massive bleeding recurred after 1 hour of UAE. Hysterectomy was performed and pathological findings of the uterus showed that there was no coagulation in the vessels, which was supposed to be observed by the effect of gelatin sponge. In addition, despite the fact that no coagulation was found, only one gelatin sponge was found in 16 slices of the uterine wall specimens. We speculate that thrombotic materials were caught in vasoconstricted vessels triggered by hypovolemic shock due to acute blood loss, and then the gelatin sponge could be washed out after recovering to normalized circulation status leading to recurrent massive hemorrhage.

Transcatheter arterial embolization with spherical embolic agent for pulmonary metastases from renal cell carcinoma

PURPOSE

This retrospective study aimed to evaluate the safety and local efficacy of transcatheter arterial embolization (TAE) with superabsorbent polymer microspheres (SAP-MS) in patients with pulmonary metastases from renal cell carcinoma (RCC).

METHODS

Sixteen patients with unresectable pulmonary metastases from RCC refractory to standard therapy were enrolled to undergo TAE with the purpose of mass reduction and/or palliation. The prepared SAP-MS swell to approximately two times larger than their dry-state size (100-150 μm [n = 14], 50-100 μm [n = 2]). Forty-nine pulmonary nodules (lung n = 22, mediastinal lymph node n = 17, and hilar lymph node n = 10) were selected as target lesions for evaluation. Local tumor response was evaluated 3 months after TAE according to Response Evaluation Criteria in Solid Tumors (RECIST; version 1.1). The relationship between tumor enhancement ratio by CT during selective angiography and local tumor response was evaluated.

RESULTS

The number of TAE sessions per patient ranged from 1 to 5 (median 2.9). Embolized arteries at initial TAE were bronchial arteries in 14 patients (87.5 %) and nonbronchial systemic arteries in 11 patients (68.8 %). Nodule-based evaluation showed that 5 (10.2 %) nodules had complete response, 17 (34.7 %) had partial response, 15 (30.6 %) had stable disease, and 12 (24.5 %) had progressive disease. The response rate was significantly greater in 22 lesions that had a high tumor enhancement ratio than in 27 lesions that had a slight or moderate ratio (90.9 vs. 7.4 %, p = 0.01). Severe TAE-related adverse events did not occur.

CONCLUSION

TAE with SAP-MS might be a well-tolerated and locally efficacious palliative option for patients with pulmonary metastases from RCC.

Treatment failure after uterine artery embolization: prospective cohort study with multifactorial analysis of possible predictors of long-term outcome

PURPOSE

To evaluate the impact of baseline characteristics and residual leiomyoma perfusion after uterine artery embolization (UAE) on clinical long-term outcome.

MATERIALS AND METHODS

One hundred fifteen patients underwent UAE. All patients were divided into three groups according to achieved infarction rate determined on contrast-enhanced magnetic resonance imaging within 48-72 h after UAE (I: 100%, n=60; II: 90-99%, n=32; and III: 0-89%, n=23). Treatment failure and subsequent re-interventions (surgery, repeat UAE) were assessed for each group and compared using Cox regression analysis (CRA) with respect to the following baseline variables: age, uterine and dominant fibroid volume, number of fibroids, location of largest fibroid, and clinical symptoms.

RESULTS

Long-term follow-up was completed after a median of 7.2 years (range 5.1-9.6) with a response rate of 84%. CRA revealed that patients in group III had a 22.2-fold higher risk (p<0.001) of treatment failure than patients in group I, whereas groups I and II did not differ significantly (p=0.578). For patients with bleeding-related symptoms only, CRA showed a 5.1-fold higher risk (p=0.025) of treatment failure than for patients with equally dominant bleeding- and bulk-related symptoms. A 40.5-fold higher likelihood (p<0.001) of treatment failure was observed for patients in group III with bleeding-related symptoms only compared to those in group I with combined bleeding- and bulk-related symptoms.

CONCLUSION

Incomplete fibroid infarction after UAE is strongly associated with the risk of experiencing treatment failure. Patients with bleeding-related complaints only face the highest likelihood of treatment failure if UAE results in less than 90% fibroid devascularization.

Comparison of clinical outcomes of tris-acryl microspheres versus polyvinyl alcohol microspheres for uterine artery embolization for leiomyomas: results of a randomized trial

PURPOSE

To compare tris-acryl microspheres and polyvinyl alcohol (PVA) microspheres as embolic agents in uterine artery embolization (UAE) for uterine leiomyomas in terms of clinical outcome, inflammatory response, and adverse reactions.

MATERIALS AND METHODS

A double-blinded randomized controlled trial was performed, with 27 patients in the tris-acryl microsphere group and 29 in the PVA microsphere group. The primary endpoint was clinical success, defined as a 2-year freedom from subsequent surgery as a result of persistent or deteriorated symptoms. Secondary endpoints included (i) posttreatment leiomyoma enlargement, (ii) leiomyoma volume reduction at 3 and 9 months, (iii) significant residual intratumoral perfusion, (iv) increase in inflammatory and stress markers, (v) incidence of complications, and (vi) duration of hospital stay.

RESULTS

There was no statistically significant difference between the two groups in patient demographics, clinical presentation, initial tumor findings, change in inflammatory and stress markers after treatment, incidence of complications, and duration of hospital stay. Tris-acryl microspheres were associated with a higher rate of clinical success than PVA microspheres (96.3% [26 of 27] vs 69% [20 of 29]; P = .012), a lower incidence of posttreatment leiomyoma enlargement (P = .030), and a lower incidence of significant residual intratumoral perfusion (P = .030).

CONCLUSIONS

In the treatment of uterine leiomyomas, UAE with tris-acryl microspheres was associated with a higher clinical success rate, a lower incidence of tumor enlargement, and no significant differences in adverse reactions and inflammatory response compared with the use of PVA microspheres. Tris-acryl microspheres therefore represent the preferred agent for UAE of uterine leiomyomas.

Uterine artery embolization for the treatment of adenomyosis

Adenomyosis is a benign uterine disorder that causes menorrhagia and dysmenorrhea. Although it was once considered a contraindication to uterine artery embolization, several authors have examined whether adenomyosis can be treated with uterine artery embolization. This article reviews the pathophysiology of adenomyosis, its imaging characteristics, as well as recent studies evaluating the efficacy of uterine artery embolization for treatment of adenomyosis.

Uterine artery embolization with trisacryl gelatin microspheres in women treated for leiomyomas: a clinicopathologic analysis of alterations in gynecologic surgical specimens

To characterize the histologic range of alterations due to uterine artery embolization with trisacryl gelatin microspheres in gynecologic specimens containing leiomyomas in detail, we report our clinicopathologic experience with 26 cases (longest postuterine artery embolization interval, 1.9 yr). Microspheres were observed in 85% of cases and could be seen up to 1.9 years after embolization. They were mainly present in leiomyomas and nonneoplastic myometrium but could be found in other nontargeted sites, such as the cervix, endometrium, ovaries, and fallopian tubes; however, infarction (present in 96% of cases) was confined to leiomyomas and did not involve other nonneoplastic tissues. The appearance of the infarcts was correlated with time after embolization, and coagulative necrosis/necrosis of indeterminate type was restricted to the early period after uterine artery embolization (before 10 wk postuterine artery embolization) whereas hyaline necrosis was seen predominantly in the late period (mostly after 10 wk, up to 1.9 yr). Of the 14 hysterectomy specimens with microspheres in extravascular spaces (almost all of which were in close proximity to the arteries), pseudoaneurysms were also focally present in 8 (57%) specimens. Microspheres were usually associated with mild inflammatory reactions, which persisted >1 year after embolization but did not become more severe over time. Morphologic and histochemical features of trisacryl gelatin microspheres were compared with other embolization agents, which can also be encountered in surgical specimens [polyvinyl alcohol (PVA) particles and PVA microspheres]. Trisacryl gelatin microspheres were negative with periodic acid-Schiff and orange-pink with Movat stains whereas PVA was positive with periodic acid-Schiff and black with Movat. Our study, the largest histologic analysis to date, confirms and extends the observations of earlier studies of trisacryl gelatin microspheres. In addition, we conclude that, as expected, the histologic appearance of microsphere-induced infarcts is a function of time, similar to healing of infarcts in nongynecologic sites. Pseudoaneurysms are a likely mechanism for the production of microspheres in extravascular spaces. Inflammation associated with microspheres can persist in gynecologic tissues but does not seem to result in the destruction of nontargeted sites. Finally, trisacryl gelatin microspheres can be distinguished from PVA particles and PVA microspheres based on a combination of morphologic features and histochemical stains.

Polymeric Microspheres for Medical Applications

Synthetic polymeric microspheres find application in a wide range of medical applications. Among other applications, microspheres are being used as bulking agents, embolic- or drug-delivery particles. The exact composition of the spheres varies with the application and therefore a large array of materials has been used to produce microspheres. In this review, the relation between microsphere synthesis and application is discussed for a number of microspheres that are used for different treatment strategies.

Arterial distribution characteristics of Embozene particles and comparison with other spherical embolic agents in the porcine acute embolization model

PURPOSE

To determine the arterial distribution pattern of the embolic agent Embozene within the porcine kidney and compare it with those of other spherical embolic agents.

MATERIALS AND METHODS

Embozene, Embosphere, Bead Block, and Contour SE in size classes of 100-300 microm, 500-700 microm, and 700-900 microm and Embozene and Embosphere in the size class of 40-120 microm were used for total arterial occlusion in minipig kidneys. Organs were evaluated microscopically regarding vascular distribution of the different embolic agents and particle sizes.

RESULTS

The following variations of arterial distribution were identified. In the 40-120-microm size class, Embosphere particles penetrated significantly deeper compared with Embozene (P = .04). In the 100-300-microm size class, Bead Block showed a significantly deeper distribution as microscopy identified particles in arteries much smaller than their nominal size. In the 500-700-microm size class, Embosphere and Contour SE showed a deeper distribution. The most uniform arterial distribution was observed in the 700-900 microm size class,. However, few Embosphere and Contour SE particles were found in arcuate arteries, also indicating a distal distribution.

CONCLUSIONS

Throughout the four most-used size classes, from very small (40-120 microm) to large (700-900 microm), the distribution characteristics of the four tested materials vary substantially. Particularly, small Embosphere particles and small Bead Block particles showed a more distal distribution, as did medium-sized Embosphere and Contour SE particles. In the largest investigated size class, the distribution was more uniform. In general, the Embozene particles are very uniform in size, and they seem to reach vessels closely corresponding to their nominal size.

Smooth Muscle Tumors of the Female Genital Tract

Smooth muscle tumors are the most common among mesenchymal tumors in the female genital tract. The vast majority of these neoplasms are clinically benign and easy to diagnose. In contrast, leiomyosarcomas are highly aggressive tumors that may pose considerable diagnostic problems when they display unusual (myxoid or epithelioid) morphology, ambiguous histologic features for malignancy, or an unusual anatomic distribution. Diagnostic criteria for these problematic tumors vary depending on the site and type of histologic differentiation, and are based on a combination of 3 major criteria: (1) moderate to severe cytologic atypia; (2) increased mitotic index; and (3) tumor cell necrosis. Certain benign smooth muscle proliferations may show worrisome histologic features or unusual growth patterns, causing concern for leiomyosarcoma. Furthermore, other tumors, including perivascular epithelioid tumors, may mimic leiomyosarcoma. Careful attention to the clinical and anatomic setting, cytologic and architectural features, and immunohistochemical characteristics are helpful in distinguishing these entities. This article discusses conventional smooth muscle tumors as well as unusual subtypes, with emphasis on the diagnostic criteria and problems in differential diagnosis that arise at each site within the female genital tract.

Early-stage morphological observations of myoma and myometrium after laparoscopic uterine artery occlusion treatment

OBJECTIVE

Myoma therapy by uterine artery occlusion using laparoscopic ligation (UAOL) has been performed for many years and has proven effective, but limited information is available on its therapeutic mechanism. To examine this issue, we conducted this study to investigate the morphological change and apoptosis occurring in myomal and adjacent myometrial tissues shortly after UAOL.

STUDY DESIGN

In total, 16 myomas and adjacent myometrium were obtained from 7 cases before and at various points after artery ligation. The tissues were stained using hematoxylin and eosin for morphological observation. To investigate the existence of apoptosis, in situ immunostaining of Caspase 3 and TUNEL assay were performed. Cytochrome C released from mitochondria was also detected by immunohistochemistry.

RESULTS

Microscopic observation found that after UAOL, both myometrial and myomal tissues were edematous and apoptotic cells were widespread in both tissues. TUNEL assays showed that before UAOL, numbers of apoptotic cells in myomal and myometrial tissues had no significant differences (P=0.866). After ischemia of (36.69+/-18.53) min, apoptosis was significantly more elevated in myoma than in myometrium ((6.43+/-4.38)/10 HPF vs. (2.74+/-1.95)/10 HPF, P=0.003). Caspase 3 stain shared similar features with the TUNEL assay. In both groups cytochrome C was released from mitochondria after UAOL, and more was detected in the myoma.

CONCLUSION

UAOL is an alternative method to treat symptomatic uterine myomas. Apoptosis via mitochondrial pathways may lead to reduction of the volume of myoma and myometrium and eventual relief of symptoms.

Microspheres and nonspherical particles for embolization

Last years, calibrated microspheres have proven their superiority in targeting embolization over non spherical particles in many applications. For the very near future they represent the best tool for controlling drug delivery in chemoembolization, under the two conditions that they would be image detectable and that the "dosimetry" would be tailored to pathological process.

Hysteroscopy after uterine fibroid embolization in women of fertile age

AIM

Uterine artery embolization for fibroids is a controversial issue for women with incomplete reproductive plans. Ovarian failure and uterine infection are the most dreaded complications of this procedure. The purpose of the present study was to assess the types and the frequency of intrauterine abnormalities and the histological features of the endometrium after embolization.

METHODS

Uterine artery embolization was performed on 51 women (average age 34.5 years) with intramural fibroid/s larger than 4 cm. Hysteroscopy and endometrial biopsy was performed from 3 to 9 months later in the luteal phase of the cycle.

RESULTS

Despite all women having no major symptoms prior to hysteroscopy, only 19 (37%) had completely normal hysteroscopic findings. There was intrauterine protrusion of fibroid/s in 19 cases (37%), yellowish coloration of the endometrium in 14 (28%), intrauterine or cervical adhesions in seven (14%), and communication between the myoma and the uterine cavity in five cases (10%). A normal, functional endometrium was histologically verified in 44 women of 49 (90%) who could be evaluated. Regressive changes (necrosis or hyalinization) of leiomyoma or of indefinite origin were found in 17 patients and embolization particles in five, including one patient with microspheres inside the endometrial vessel. No case of Asherman syndrome or endometrial atrophy was observed.

CONCLUSION

The frequency of abnormal hysteroscopic findings after embolization is surprisingly high. The clinical significance, reversibility, and impact on fertility of abnormal hysteroscopic findings after embolization remain unclear. Regardless, hysteroscopy should be strongly recommended to all patients after uterine fibroid embolization, prior to conception.

MR Imaging Detection of Superparamagnetic Iron Oxide–loaded Tris-acryl Embolization Microspheres

PURPOSE

To assess by magnetic resonance (MR) imaging the detectability of superparamagnetic iron oxide (SPIO)-labeled microspheres (MSs) in vitro on gelose, ex vivo in kidneys from embolized sheep, and in vivo in kidneys from embolized pigs.

MATERIALS AND METHODS

With various sizes of SPIO-labeled MSs, common neck and pelvic spin-echo and gradient-echo sequences were acquired on a 1.5-T MR unit. SPIO-labeled MSs of four sizes were embedded in a hydrogel as single MSs or in multiple units, or multiplets. Detection rate on MR imaging was assessed according to the real size and number of MSs. SPIO-loaded and unloaded MSs of four sizes were injected into eight sheep kidneys, which underwent MR and pathologic examinations. For each size, the location of MSs in renal vasculature was determined and compared according to the technique used. Kidneys were embolized in pigs with various amounts of MSs in three sizes. MR was performed immediately after embolization and SPIO-labeled MS detection was assessed according to size, organ, and amount injected. Results SPIO-labeled MSs provide a low signal intensity on T1-weighted sequences, without distortion. In vitro, 28% of 100-300-microm single MSs were detected and more than 80% were detected for larger sizes. MS multiplets were all detected in all sizes. Ex vivo, all sizes of MSs were detected by MR imaging in kidneys, whereas control MSs were not observed. Histologic analysis showed that there was no difference in vascular distribution between SPIO-labeled MS and control MSs, and therefore for each caliber (P > .05). Arterial location of SPIO-labeled MSs was the same on MR imaging and histologic analysis. In vivo, SPIO-labeled MS were detected in the kidney vasculature when volumes greater than 1 mL of 100-300-microm or 500-700-microm MSs were injected. Volumes lower than 1 mL SPIO-labeled MSs were hardly detected in kidneys, regardless of MS size. Conclusions SPIO-labeled MSs are detected by MR imaging with common gradient-echo sequences in vitro in gelose and ex vivo and in vivo in kidneys. SPIO-labeled MSs could allow better control of embolization and thereby enhance efficacy and safety of the procedure.

Leiomyosarcoma with dedifferentiation in a premenopausal patient discovered after uterine artery embolization

Although a hysterectomy is the most common treatment for relieving the symptoms attributable to uterine leiomyomas, uterine artery embolization (UAE) is now being used more frequently as an alternative to a hysterectomy. However, it is difficult to differentiate a leiomyoma from a leiomyosarcoma without performing a pathological examination. Reported herein is a rare case of leiomyosarcoma that showed dedifferentiation of the tumor cells after UAE. A premenopausal 48-year-old woman had been suffering from hypermenorrhea for 4 years before visiting the clinic. She underwent UAE for suspected symptomatic leiomyoma. Two months later, dilatation and curettage was performed because of genital bleeding and a necrotic mass was submitted for pathological examination. Three months after curettage, with renewed symptoms, endometrial biopsy was done, which confirmed pleomorphic sarcoma. Metastatic nodes to the lung were also found at that time. Multiple leiomyosarcomas and a leiomyosarcoma showing dedifferentiation of the uterine body were found on pathological examination. The patient had metastatic nodes to the brain later and died of metastatic disease 20 months in total after UAE. This is a rare case of leiomyosarcoma with dedifferentiation and multiple metastases occurring after UAE, suggesting that dedifferentiation could be derived from ordinary leiomyosarcoma and that the traumatic effect of curettage might cause early metastasis. The present case is a warning that careful and detailed evaluation of the uterine tumor are needed before UEA.

Uterine artery embolization for symptomatic adenomyosis with or without uterine leiomyomas with the use of calibrated tris-acryl gelatin microspheres: midterm clinical and MR imaging follow-up

PURPOSE

To evaluate clinical and magnetic resonance (MR) imaging results after uterine artery embolization (UAE) in women with symptomatic adenomyosis with or without uterine leiomyomas.

MATERIALS AND METHODS

Thirty-eight women with symptomatic adenomyosis with or without uterine leiomyomas were treated with UAE with calibrated tris-acryl gelatin microspheres. Based on MR findings, women were categorized as having pure adenomyosis (group A; n = 15), adenomyosis dominance with fibroid tumors (group B; n = 14), or fibroid tumor dominance with adenomyosis (group C; n = 9).

RESULTS

Heavy menstrual bleeding, pain, and bulk-related symptoms at last follow-up at a median of 16.5 months (range, 3-38 months) were compared with baseline symptoms. With follow-up MR imaging at a median of 12 months (range, 3-36 months), changes in uterine volume, leiomyoma volume, junctional zone thickness, and contrast enhancement of adenomyosis were assessed. After embolization, adenomyosis infarction could be depicted on contrast medium-enhanced MR in 44.1% of cases. Median reductions of uterine volume, fibroid tumor volume, and junctional zone thickness were 44.8%, 77.1%, and 23.9%, respectively. In group A, three patients needed additional surgery after UAE, in addition to two in group B and one in group C. In the remaining 32 patients, except for one patient in group C, all preexisting symptoms (eg, bleeding, pain, bulk-related symptoms) improved or resolved after UAE. Overall, 84.2% of women were satisfied with the results of UAE.

CONCLUSION

In this study, midterm results (at a median of 16.5 months) showed that UAE in symptomatic adenomyosis with or without uterine leiomyomas is effective. Hysterectomy was avoided in the vast majority of patients. MR imaging showed reduction of uterine volume and junctional zone thickness.

Utero-Ovarian Anastomosis: Histopathologic Correlation after Uterine Artery Embolization with or without Ovarian Artery Embolization

PURPOSE

To study utero-ovarian anastomosis at angiography and its histologic effect on patients who were treated with uterine artery embolization (UAE) with or without ovarian artery embolization (OAE) for symptomatic uterine leiomyomata.

MATERIALS AND METHODS

Four hundred patients (mean age, 43.6 years +/- 6.34) underwent UAE at the authors' institution from June 1998 to May 2005. Eight of the 400 patients underwent hysterectomy with removal of at least one adnexae after UAE. Five patients received tris-acryl gelatin microspheres and three received polyvinyl alcohol particles. Two patients also underwent OAE with gelatin sponges. Specimens from 16 fallopian tubes and 12 ovaries were reviewed. Histologic slides were prepared and reviewed by two pathologists who were blinded to the angiographic findings. The presence of utero-ovarian anastomoses at angiography, the histologic features of adnexa, the presence of particles in the adnexa, and the size and location of the particles were studied.

RESULTS

Utero-ovarian anastomosis was present at angiography in three of the eight patients (38%) and five of the 16 adnexa (31%). Particles were present within the fallopian tube or ovary in all patients who demonstrated utero-ovarian anastomoses at angiography. When utero-ovarian anastomoses were identified bilaterally, particles were found in both adnexae. In cases with particles in the adnexa, the adnexal tissues were histologically viable without evidence of ischemic changes or infarction. Particles were not present in the ovary of patients without utero-ovarian anastomosis at angiography.

CONCLUSION

The angiographic finding of a utero-ovarian anastomosis during UAE appears to correlate with particle embolization in the fallopian tube or ovary. Histologically normal fallopian tubes and ovaries can be expected after UAE with microsphere particles with and without OAE with gelatin sponges.

Pathological findings of uterine leiomyomas and adenomyosis following uterine artery embolization

Uterine artery embolization (UAE) is an effective and accepted treatment option for symptomatic uterine leiomyoma. Between 2000 and 2005, 91 women were treated using this method, and were prospectively followed at our institution. Twenty of them subsequently underwent surgery. One of these patients was subjected to four surgical procedures. We describe the pathological findings of 23 surgical specimens obtained from these 20 patients. The embolic material used consisted of tris-acryl gelatin microspheres (TGMS) in 15 patients (18 surgical specimens), polyvinyl alcohol particles (PVA) in three patients, and a combination of PVA and TGMS in two patients. Histologically, of the 23 specimens examined, 20 were diagnosed as leiomyomas, and three as adenomyosis. Particles used for embolization were found in all but three specimens. Necrosis was present in 15 of 20 leiomyoma specimens. Hyaline necrosis was found in 12 specimens, coagulative necrosis in one case, and a combination of hyaline and coagulative or suppurative necrosis in two cases. The foci of adenomyosis remained unaltered.

Characterization of acrylic polyamide plastic embolization particles in vitro and in human tissue sections by light microscopy, infrared microspectroscopy and scanning electron microscopy with energy dispersive X-ray analysis

Vascular embolization is a well-established practice for the treatment of tumors and vascular lesions. Rounded beads (microspheres) of various materials (collagen, dextran and trisacryl-polymer-gelatin) were developed to solve problems encountered with earlier versions of embolic material. We performed histochemistry, Fourier transform infrared microspectroscopy and scanning electron microscopy with energy dispersive X-ray analysis on two uterine and one hepatic specimen with unidentified intravascular foreign material, and examined a reference embolization product for comparison. The hematoxylin and eosin stained tissue sections showed multiple foci with unidentified intravascular foreign material and fibrous obliteration of vessel lumens. Only one case had a clinical history of previous embolization but without specifying the material used. One case was submitted for identification of a 'parasite'. The material stained positively with Sirius red and mucicarmine, variably with Masson's trichrome stain and Movat pentachrome, and did not stain centrally with periodic acid Schiff with diastase. Infrared spectrophotometric analysis of the material from all three cases demonstrated the spectrum of acrylic polyamide plastic. A control sample of EmboGold exhibited infrared microspectroscopic spectra similar to the three tissue specimens. Analysis by scanning electron microscopy with energy dispersive X-ray analysis demonstrated some differences in elemental composition between the tissue sections and the selected reference material. To our knowledge, this is the first report of infrared spectrophotometric analysis with scanning electron microscopy with energy dispersive X-ray analysis of an acrylic polyamide plastic embolization product both in vitro and in human histologic tissue sections. In cases lacking appropriate clinical information, identification by these methods and/or a panel of special stains may assist pathologists unfamiliar with this material's light microscopic appearance.

The normal human myometrium has a vascular spatial gradient absent in small fibroids

BACKGROUND

The human uterine vasculature is highly structured, exhibiting circumferential and radial branching. Previously published angiograms of the arterial network describe a system of regular coils. Uterine fibroids lack this structured vasculature. In this study, we make a comparison between the vasculature in normal myometrium and in fibroids using robust stereological methods thus far lacking in the literature.

METHODS

Stereological and morphometric analysis of the vascular system was carried out on 15 normal and 27 small fibroid (5-40 mm) uteri taken from women suffering menorrhagia. Projected images of published angiograms were also re-examined, measuring tortuosity.

RESULTS

A decreasing gradient of vascular smooth muscle from outer to inner myometrium was found in normal uteri, with no corresponding gradient in capillary tissue fraction. An association between vascular luminal size, amplitude and frequency of vessel bending was also established. Conversely, fibroids were found to lack structured or muscularized vasculature.

CONCLUSIONS

A quantitative gradient within the myometrial vascular system, which is absent in fibroids, has been demonstrated. These structural differences between diseased and healthy tissues are probably because of differing expression of angiogenic growth factors and may explain the distribution of particles seen after uterine artery embolization.

Expanding treatment options for women with symptomatic uterine leiomyomas: timely medical breakthroughs

Only during the last decade has there been a flourishing of alternative treatment options to major surgery for the management of symptomatic uterine leiomyoma. In addition to currently available minimally invasive surgical interventions, such as endometrial ablation techniques, radiologic interventions with uterine artery embolization and focused ultrasound surgery are welcome treatment options, despite the lack of long-term efficacy data.