Embolization of uterine arteriovenous malformation causing postpartum hemorrhage using n-butyl cyanoacrylate: A case report

Uterine artery arteriovenous malformations (AVMs) are rare anomalies that may result in uterine hemorrhage. A 40-year-old G8P5126 woman presented with severe vaginal bleeding and an estimated 2000 mL of blood loss at home. Three weeks prior, she had a vaginal delivery of a term infant resulting in post-partum hemorrhage, with 2700 mL of blood loss. The patient had a history of ectopic pregnancy, placenta previa, and dilatation and curettage. Interventional radiology was consulted, and the patient underwent angiography of the internal iliac and uterine arteries revealing the presence of a uterine AVM, which was successfully embolized using a thick mixture of n-butyl cyanoacrylate and lipiodol. The patient experienced no further episodes of bleeding and was discharged within 24 hours. Recognition of typical symptoms and risk factors for uterine arteriovenous malformations can facilitate early diagnosis and appropriate treatment.

Type II Endoleak Nidus Volume on Arterial and Delayed Phases of Initial CT Angiography after Endovascular Abdominal Aortic Aneurysm Repair Predicts Persistent Endoleak and Aneurysm Sac Enlargement

Purpose

To evaluate type II endoleak nidus volume (ENV) in the arterial phase (ENV_AP) and delayed phase (ENV_DP) of the first postoperative CT angiography (CTA) as a predictor of persistent endoleak and aneurysm sac enlargement at follow-up CTA in patients with endovascular aneurysm repair (EVAR) of abdominal aortic aneurysm.

Materials and Methods

Ninety-three patients (mean age ± standard deviation, 72 years ± 8; range, 56-88 years) with EVAR and type II endoleak were included in a single-institution retrospective study conducted between March 1, 2005, and December 31, 2018. ENV_AP, ENV_DP, change of volume (ENV_DP-AP), and percentage of ENV_AP and ENV_DP in aneurysm sac volume (ASV) (ENV_AP/ASV%, ENV_DP/ASV%, respectively) were measured on first postoperative CTA images. The mean follow-up was 31.6 months ± 26.6 (range, 6-163.8 months). Patients were divided into two groups (group A, spontaneous resolution of endoleak without intervention [n = 29] and group B, persistent endoleak at follow-up CTA [n = 64]) and compared by using the Mann-Whitney U, Wilcoxon signed rank, and Pearson χ² tests. Receiver operating characteristic (ROC) analysis was used to compare accuracies of parameters at first postoperative CTA.

Results

The accuracy of ENV_DP (area under the ROC curve [AUC], 0.78) was superior to the accuracy of ENV_DP/ASV% (AUC, 0.76), ENV_DP-AP (AUC, 0.74), ENV_AP (AUC, 0.71), and ENV_AP/ASV% (AUC, 0.69) in indicating persistent endoleak. In group B, 46 patients (72%) showed ASV enlargement and 44 patients (69%) underwent endoleak embolization. ENV_AP (1.7 cm³ ± 2.9 vs 3.4 cm³ ± 4.2; P = .001), ENV_DP (2.9 cm³ ± 3.8 vs 8.0 cm³ ± 9.6; P < .001), ENV_DP-AP (1.1 cm³ ± 1.8 vs 4.5 cm³ ± 7.8; P < .001), ENV_AP/ASV% (0.9% ± 1.5 vs 1.7% ± 2.2; P = .003), and ENV_DP/ASV% (1.6% ± 2.2 vs 3.7% ± 3.6; P < .001) were smaller in group A than in group B.

Conclusion

ENV_DP of the first postoperative CTA is an accurate predictor of persistent endoleak compared with ENV_AP, and persistent endoleak is associated with aneurysm sac enlargement, in which earlier intervention is recommended.© RSNA, 2021.

CT-Guided Percutaneous Drainage Catheter Placement in the Abdomen and Pelvis: Predictors of Outcome and Protocol for Follow-up

PURPOSE

To determine predictors of outcomes for patients who undergo computed tomography (CT)-guided percutaneous abdominal or pelvic drainage catheter placement and to identify which patients benefit from fluoroscopic drainage catheter interrogation (abscessogram).

MATERIALS AND METHODS

A retrospective review of 383 patients (mean, 52 years old; range 8-89 years old; 158 males: 225 females) who underwent 442 CT-guided procedures and 489 catheter placements for fluid collections in the abdomen or pelvis from January 1, 2015, to December 31, 2016 was performed. Variables including underlying disease, fluid location, number of collections drained, number of catheter exchanges and follow-up abscessograms performed, catheter size, and fistula detection were analyzed to determine factors associated with fistula formation and increased catheter dwell time.

RESULTS

A single abscessogram followed by catheter removal was performed for 217 catheters (44%). An increased number of abscessograms was significantly associated with drainage catheter size (P < .001) and presence of a fistula (P < .001). Fistulae were detected in 95 cases (19%) and were significantly associated with an increased number of drain exchanges (P < .001) and an underlying diagnosis of Crohn's disease (P = .02). Based on these data, a clinical algorithm for drain management is presented.

CONCLUSIONS

Abscessograms performed after CT-guided percutaneous drainage catheter placement are useful to detect catheter malposition, occluded catheters, and fistulae but are not necessary for all patients. If performed selectively, particularly in patients with an underlying diagnosis of Crohn's disease or those at high risk for developing fistulae, unnecessary examinations can be avoided, reducing cost, extra hospital visits, and radiation dose.

Review of Current Literature for Prostatic Artery Embolization

Prostatic artery embolization (PAE) is an emerging, novel interventional technique in the management of patients with lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH). BPH is a common clinical condition in middle-aged and elderly men resulting in LUTS, including nocturia, urinary frequency, urgency, decreased urinary flow rates, hesitancy, and incomplete bladder emptying. Traditionally, LUTSs have been managed by medical or surgical therapies. Since the initial incidental discovery that selective PAE performed for uncontrolled bleeding secondary to BPH resulted in improved LUTS, the technique has continually evolved with a growing body of evidence supporting its safety and efficacy. However, despite the available data, PAE has yet to be established as a standard-of-care treatment option for patients with LUTS/BPH. In this article, the authors review the history and current state of PAE, including published data from case reports, animal studies, retrospective/prospective cohort studies, and prospective randomized controlled trials.

Comparison of percutaneous ablation technologies in the treatment of malignant liver tumors

Tumor ablation is a minimally invasive technique used to deliver chemical, thermal, electrical, or ultrasonic damage to a specific focal tumor in an attempt to achieve substantial tumor destruction or complete eradication. As the technology continues to advance, several image-guided tumor ablations have emerged to effectively manage primary and secondary malignancies in the liver. Percutaneous chemical ablation is one of the oldest and most established techniques for treating small hepatocellular carcinomas. However, this technique has been largely replaced by newer modalities including radiofrequency ablation, microwave ablation, laser-induced interstitial thermotherapy, cryoablation, high-intensity-focused ultrasound ablation, and irreversible electroporation. Because there exist significant differences in underlying technological bases, understanding each mechanism of action is essential for achieving desirable outcomes. In this article, the authors review the current state of each ablation method including technological and clinical considerations.

ACR Appropriateness Criteria radiologic management of hepatic malignancy

Management of hepatic malignancy is a challenging clinical problem involving several different medical and surgical disciplines. Because of the wide variety of potential therapies, treatment protocols for various malignancies continue to evolve. Consequently, development of appropriate therapeutic algorithms necessitates consideration of medical options, such as systemic chemotherapy; surgical options, such as resection or transplantation; and locoregional therapies, such as thermal ablation and transarterial embolization. The authors discuss treatment strategies for the 3 most common subtypes of hepatic malignancy treated with locoregional therapies: hepatocellular carcinoma, neuroendocrine metastases, and colorectal metastases. The ACR Appropriateness Criteria(®) are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

ACR Appropriateness Criteria radiologic management of benign and malignant biliary obstruction

The optimal treatment for patients with biliary obstruction varies depending on the underlying cause of the obstruction, the clinical condition of the patient, and anticipated long-term effects of the procedure performed. Endoscopic and image-guided procedures are usually the initial procedures performed for biliary obstructions. Various options are available for both the radiologist and endoscopist, and each should be considered for any individual patient with biliary obstruction. This article provides an overview of the current status of radiologic procedures performed in the setting of biliary obstruction and describes multiple clinical scenarios that may be treated by radiologic or other methods. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Endovascular management of acute upper extremity deep venous thrombosis and the use of superior vena cava filters

Upper extremity deep venous thrombosis (UEDVT), though less common than lower extremity DVT, is a significant problem with several possible etiologies. The incidence of UEDVT is on the rise, primarily from the increasing use of central venous access devices. However, there are other causes of UEDVT, including primary venous thrombosis (Paget-Schroetter syndrome) and hypercoagulable states associated with underlying malignancy. The morbidity and mortality associated with UEDVT is largely from pulmonary embolism and the postphlebitic syndrome. Nevertheless, many UEDVTs are asymptomatic or patients may present with nonspecific clinical symptoms; therefore, a high index of suspicion is often necessary to make a correct diagnosis. Currently, there is no standard treatment algorithm for UEDVT. Treatment options may range from systemic anticoagulation to surgical correction depending on the etiology of the thrombus, as well as the patient's associated comorbidities, life expectancy and expected quality of life following treatment.

Development of an animal model for radiofrequency ablation of primary, virally induced hepatocellular carcinoma in the woodchuck

PURPOSE

To develop a consistent and reproducible method in an animal model for studies of radiofrequency (RF) ablation of primary hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Fifteen woodchucks were inoculated with woodchuck hepatitis virus (WHV) to establish chronic infections. When serum γ-glutamyl transpeptidase levels became elevated, the animals were evaluated with ultrasound, and, in most cases, preoperative magnetic resonance (MR) imaging to confirm tumor development. Ultimately, RF ablation of tumors was performed by using a 1-cm probe with the animal submerged in a water bath for grounding. Ablation effectiveness was evaluated with contrast-enhanced MR imaging and gross and histopathologic analysis.

RESULTS

RF ablation was performed in 15 woodchucks. Modifications were made to the initial study design to adapt methodology for the woodchuck. The last 10 of these animals were treated with a standardized protocol using a 1-cm probe that produced a consistent area of tumor necrosis (mean size of ablation, 10.2 mm × 13.1 mm) and led to no complications.

CONCLUSIONS

A safe, reliable and consistent method was developed to study RF ablation of spontaneous primary HCC using chronically WHV-infected woodchucks, an animal model of hepatitis B virus-induced HCC.

Utilization of Interventional Radiology in the Postoperative Management of Patients after Surgery for Locally Advanced and Recurrent Rectal Cancer

The surgical management of locally advanced primary rectal cancer and locally recurrent rectal cancer requires complex operations frequently resulting in complicated postoperative courses. We sought to evaluate the utilization of interventional radiologic (IR) procedures in the management of postoperative complications. Under Institutional Review Board approval, a prospective database of colorectal cancer patients undergoing resection from July 1999 to January 2010 was analyzed. Data collected included demographics, operative procedure, complications, length of stay, and IR utilization. Fisher's exact tests and logistic regression explored associations with necessitating an IR procedure during the postoperative period. Continuous variables were analyzed using Wilcoxon rank sum tests. One hundred and one patients underwent surgery and 66 received intraoperative electron radiotherapy (IOERT). Primary procedures included pelvic exenteration (n = 35), abdominoperineal resection (n = 25), low anterior resection (n = 23), paraaortic node dissection (n = 7), resection of isolated pelvic/retroperitoneal tumor (n = 7), and colectomy (n = 4). Sixty-two patients required multivisceral resection including partial/total cystectomy (n = 30), small bowel resection (n = 25), oophorectomy (n = 15), vaginectomy (n = 12), hysterectomy (n = 12), hepatectomy (n = 3), and nephrectomy (n = 3). Seventeen partial sacral resections and 47 pelvic sidewall resections were also required. One hundred and thirty-eight complications were identified in 72 patients, 30 of which required a procedural intervention. Twenty-seven IR procedures were performed including drainage of fluid collections (n = 14), nephrostomy tube placement (n = 8), arterial embolization (n = 2), inferior vena cava filter placement (n = 2), and pleural drainage (n = 1). Only three reoperations were required, none related to failure of IR procedures. There were no deaths. Estimated blood loss > 2000 mL ( P = 0.002), IOERT ( P = 0.03), and incomplete resection ( P = 0.02) were found to be associated with postoperative IR utilization. Surgery for locally advanced primary rectal cancer and locally recurrent rectal cancer is associated with significant morbidity but low mortality. IR procedures play a significant role in the postoperative management of these patients and may decrease the need for reoperation.

Utilization of interventional radiology in the postoperative management of patients after surgery for locally advanced and recurrent rectal cancer

The surgical management of locally advanced primary rectal cancer and locally recurrent rectal cancer requires complex operations frequently resulting in complicated postoperative courses. We sought to evaluate the utilization of interventional radiologic (IR) procedures in the management of postoperative complications. Under Institutional Review Board approval, a prospective database of colorectal cancer patients undergoing resection from July 1999 to January 2010 was analyzed. Data collected included demographics, operative procedure, complications, length of stay, and IR utilization. Fisher's exact tests and logistic regression explored associations with necessitating an IR procedure during the postoperative period. Continuous variables were analyzed using Wilcoxon rank sum tests. One hundred and one patients underwent surgery and 66 received intraoperative electron radiotherapy (IOERT). Primary procedures included pelvic exenteration (n = 35), abdominoperineal resection (n = 25), low anterior resection (n = 23), paraaortic node dissection (n = 7), resection of isolated pelvic/retroperitoneal tumor (n = 7), and colectomy (n = 4). Sixty-two patients required multivisceral resection including partial/total cystectomy (n = 30), small bowel resection (n = 25), oophorectomy (n = 15), vaginectomy (n = 12), hysterectomy (n = 12), hepatectomy (n = 3), and nephrectomy (n = 3). Seventeen partial sacral resections and 47 pelvic sidewall resections were also required. One hundred and thirty-eight complications were identified in 72 patients, 30 of which required a procedural intervention. Twenty-seven IR procedures were performed including drainage of fluid collections (n = 14), nephrostomy tube placement (n = 8), arterial embolization (n = 2), inferior vena cava filter placement (n = 2), and pleural drainage (n = 1). Only three reoperations were required, none related to failure of IR procedures. There were no deaths. Estimated blood loss > 2000 mL (P = 0.002), IOERT (P = 0.03), and incomplete resection (P = 0.02) were found to be associated with postoperative IR utilization. Surgery for locally advanced primary rectal cancer and locally recurrent rectal cancer is associated with significant morbidity but low mortality. IR procedures play a significant role in the postoperative management of these patients and may decrease the need for reoperation.

Bronchial artery embolization

Massive hemoptysis is a frightening and potentially life-threatening clinical event. Patients with chronic inflammatory lung diseases such as bronchiectasis, sarcoidosis, tuberculosis, and cystic fibrosis develop markedly hypertrophied and fragile bronchial arteries that may lead to clinically significant hemoptysis. Surgical intervention is hazardous and often impossible in these patients with diffuse parenchymal lung disease. Superselective catheterization of the bronchial arteries feeding the affected areas followed by particulate embolization has proven to be an effective treatment for the control of bleeding. With modern microcatheters and guidewires, bronchial artery embolization is safe and well tolerated by patients. Because this treatment does not directly influence the primary underlying disease, recurrent episodes of bleeding are likely, which will require additional embolization procedures. In patients who have undergone prior bronchial artery embolization, the dominant feeding arterial supply often originates from nonbronchial systemic collateral vessels.

Iatrogenic Ureteral Injury during Translumbar Embolization of a Type II Endoleak

The persistence of flow within an aneurysm sac remains the so-called Achilles heel of endovascular aortic aneurysm repair. The management of type II endoleaks remains controversial, although aneurysm sac expansion is an accepted indication for intervention. The present case describes a patient with a type II endoleak following endovascular repair of an abdominal aortic aneurysm treated by translumbar embolization. The procedure was complicated by iatrogenic injury to the left ureter and nontarget embolization resulting in acute ureteral obstruction.

Portal vein pseudoaneurysm with portoenteric fistula: an unusual cause for massive gastrointestinal hemorrhage

Pancreaticoduodenectomy (Whipple's procedure) is a commonly performed procedure for the treatment of pancreatic malignancies. Postoperative bleeding from adjacent arteries is a well-established complication of this procedure. This article describes an unusual case of massive gastrointestinal bleeding following pancreaticoduodenectomy due to the development of a portal vein pseudoaneurysm with a portoenteric fistula. The diagnosis was confirmed with multidetector computed tomography angiography; the different endovascular treatment options are discussed.

Use of yttrium-90 microspheres in patients with advanced hepatocellular carcinoma and portal vein thrombosis

PURPOSE

Patients with portal vein thrombosis (PVT) and hepatocellular carcinoma (HCC) have limited treatment options because of increased disease burden and diminished hepatic perfusion. Yttrium-90 ((90)Y) microspheres may be better tolerated than chemoembolization in these patients. The present study reviews the safety and efficacy of (90)Y microspheres in HCC with major PVT.

MATERIALS AND METHODS

A retrospective review of HCC with main (n = 10) or first-branch (n = 12) PVT treated with (90)Y microspheres (N = 22) was conducted. Cancer of the Liver Italian Program (CLIP) scores ranged from 2 to 5, with 18% of patients having a score of 4 or greater. Imaging response at 8-12 was based on Response Evaluation Criteria In Solid Tumors. Overall survival (OS) was estimated by the Kaplan-Meier method.

RESULTS

A total of 32 microsphere treatments (26 glass, six resin) were administered to 22 patients. Common grade 1/2 toxicities included abdominal pain (38%), nausea (28%), and fatigue (22%). Four posttreatment hospitalizations occurred, all less than 48 hours in duration. One death occurred 10 days after therapy. The partial response rate was 8% and progressive disease was seen in 42% of patients. Stable disease was achieved in 50% of treatments. Median OS was 7 months from initial treatment. Patients with Child-Pugh class A disease had a median OS of 7.7 months; those with class B/C disease had an OS of 2.7 months (P = .01). Median OS for patients with CLIP scores of 2/3 was 7 months, versus 1.3 months for those with scores of 4/5 (P = .04).

CONCLUSIONS

Yttrium-90 microspheres are tolerated in patients with HCC and major PVT. Compared with chemoembolization, rates of severe adverse events appear low. Radiographic response rates are low. The median OS of 7 months is promising and warrants further study versus systemic therapy.

Risk-group targeted inferior vena cava filter placement in gastric bypass patients

BACKGROUND

Despite a growing body of evidence guiding appropriate perioperative thromboprophylaxis in the general population, few data direct strategies to reduce deep venous thrombosis (DVT) and pulmonary embolism (PE) in the morbidly obese. We have implemented a novel protocol for venous thromboembolism (VTE) risk stratification in Roux-en-Y gastric bypass (RYGB) candidates at our institution, which augments clinical assessment with screening for thrombophilias, to guide retrievable inferior vena cava (IVC) filter utilization.

METHODS

A retrospective review of prospectively collected data from patients who underwent primary RYGB between 2001 and 2008 at the University of North Carolina at Chapel Hill was completed. During that time, clinical assessment of VTE risk was amplified by focused plasma screening for common thrombophilias (factors VIII, IX, and XI, d-dimer, fibrinogen). Preoperative prophylactic IVC filters were offered to high-risk patients. The database was reviewed for perioperative DVTs, PEs, and filter-related complications.

RESULTS

Of 330 patients, in 162 attempts, 160 had prophylactic IVC filters placed with four complications overall (2.47%). No patient had symptoms of PE during the planned 6-week filter period, though one had a PE occur immediately after filter removal (0.63%); in contrast, five of 170 patients (2.94%) without prophylactic IVC filters presented with symptomatic PE (p = 0.216). In total, 147 (91.88%) prophylactic filters were removed.

CONCLUSIONS

Risk-group targeted prophylactic inferior vena cava filter placement prior to RYGB is safe with a trend towards reduced occurrence of PE.

Use of Rigid Bronchoscopic Forceps in the Difficult Retrieval of the Günther Tulip Inferior Vena Cava Filter

Retrievable inferior vena cava (IVC) filters may, over time, become incorporated into the wall of the IVC, making subsequent removal difficult. The authors present a case in which a Günther Tulip filter was placed prophylactically before gastric bypass surgery. The retrieval hook of the filter became incorporated into the wall of the IVC, preventing the filter from being snared. Eventually, the filter was freed from the wall of the IVC and successfully removed by using rigid bronchoscopy forceps; however, the filter was damaged in the process.

Use of the viabil covered stent in the treatment of a benign biliary stricture with the subsequent development of acute pancreatitis

The use of bare metal stents for benign biliary strictures is typically avoided due to historically poor long-term patency. Thus, in patients who are not surgical candidates, the management of benign biliary strictures can be a frustrating process. This article describes a patient who developed a common bile duct stricture following a complex endovascular thoracoabdominal aneurysm repair. The stricture was treated with the placement of a covered metallic biliary stent; a procedure complicated by the development of acute pancreatitis.

Aneurysm of the inferior vena cava: case report

Venous aneurysms are uncommon. Despite their infrequency, venous aneurysms can present with significant clinical complications such as thrombosis, pulmonary embolism, and death. In this report, we present the case of a thrombosed inferior vena cava aneurysm discovered in a 16-year-old male who had deep vein thrombosis of the right lower extremity. Thrombosis of the inferior vena cava is uncommon in the pediatric population. Therefore, congenital abnormalities such as an inferior vena cava aneurysm should be considered when evaluating pediatric patients who present with deep vein thrombosis.

Transcatheter thrombolytic therapy for acute mesenteric and portal vein thrombosis

PURPOSE

The purpose of this study was to evaluate the utility of transcatheter thrombolytic therapy in 20 patients with acute or subacute (symptoms <40 days) portal and/or mesenteric vein thrombosis with severe symptoms, deteriorating clinical condition, and/or persistent symptoms despite anticoagulation.

MATERIALS AND METHODS

This retrospective study examined 12 male patients and eight female patients seen over a period of 11 years. The average age was 37.6 years. Four of the patients had previously undergone liver transplantation. An anatomic classification system was established to describe the extent of thrombus at the time of diagnosis. Patients were treated with thrombolytic therapy via the transhepatic route, common femoral vein route, and/or superior mesenteric artery route. Improvement in symptoms, avoidance of bowel resection, complications, and radiographic evidence of clot resolution were the main clinical outcomes.

RESULTS

Fifteen of the 20 patients exhibited some degree of lysis of the thrombus. Three patients had complete resolution, 12 had partial resolution, and five had no resolution. Eighty-five percent of patients (n = 17) had resolution of symptoms. Sixty percent of patients (n = 12) developed a major complication. No patients required bowel resection after thrombolytic therapy. One patient died with gastrointestinal hemorrhage and septic shock 2 weeks after thrombolytic therapy. Other major complications included bleeding and conditions requiring transfusion. No patients developed new portal or mesenteric thromboses. Two of the patients who received transplants eventually required repeat transplantation.

CONCLUSIONS

Transcatheter thrombolysis was beneficial in avoiding patient death, resolving thrombus, improving symptoms, and avoiding bowel resection. However, there was a high complication rate, indicating that this therapy should be reserved for patients with severe disease. Further evaluation of these techniques and outcomes should continue to be pursued.

CO2 Splenoportography for Evaluating the Splenic and Portal Veins before or after Liver Transplantation

The authors report their experience with CO(2) splenoportography in a retrospective review of 15 studies performed in 13 patients before or after liver transplantation. The studies were performed by injecting CO(2) through a small caliber needle introduced into the splenic parenchyma with ultrasound guidance and imaging with conventional digital subtraction techniques. The findings were compared with clinical follow-up and other imaging studies when available. Eight of the 15 studies were normal, of which two were confirmed by additional studies. Six of the 15 studies were abnormal, all of which were compared with additional studies. There was one nondiagnostic study and two false positives. There were no reported complications. The authors' experience suggests that CO(2) splenoportography is a minimally invasive method for safely and accurately evaluating the splenic and portal veins.

Synthesis of biologically active taxol analogs with modified phenylisoserine side chains

Taxol (1) is a highly potent antitumor agent, exerting its mechanism of action by promoting the assembly of stable microtubules in cells. We are reporting on the first synthesis and biological evaluation of taxol derivatives with substituted phenyl rings at the C-13 N-benzoyl-(2'R,3'S)-3'-phenylisoserine side chain of taxol (1). Two taxol derivatives were synthesized, one possessing a N-(p-chlorobenzoyl)-(2'R,3'S)-3'-phenylisoserine side chain (2) and the other one a N-benzoyl-(2'R,3'S)-3'-(p-chlorophenyl)isoserine side chain (3). The synthesis of the novel phenylisoserine side chains was achieved through the asymmetric synthesis of 3-hydroxy-4-aryl-2-azetidinone derivatives via the ester enolate-imine cyclocondensation reaction. The 2-azetidinones 14 and 15 were acylated with p-chlorobenzoyl chloride and benzoyl chloride, respectively, to form the N-acyl beta-lactams 16 and 17. Subsequent coupling of 16 and 17 to 7-(triethylsilyl)baccatin III (6) in the presence of pyridine and DMAP afforded, after removal of the protecting groups, the desired taxol analogues 2 and 3 in excellent yields. The newly synthesized derivatives 2 and 3 were tested in the tubulin assembly assay and also evaluated for their cytotoxicity against B16 melanoma cells. It was found that the taxol derivatives 2 and 3 had activity comparable to taxol (1).