Transplant Renal Interventions.

Renal transplantation is the most commonly performed solid-organ allograft surgery; in 2021, 25487 kidneys were transplanted in the United States, and nearly 42,000 adult patients were listed for transplant. As the treatment of choice for patients with end-stage renal disease, transplantation is performed at more than 250 centers. Despite a high rate of success, renal transplantation is not without complication, and the interventional radiologist plays a crucial role in the management of the postoperative patient. Knowledge of postsurgical anatomy, imaging findings, and technical challenges unique to these patients is important for the safe and effective treatment of transplant-related conditions. We offer a guide to the most common interventions in the renal transplant population, including biopsy, vascular interventions, and the management of urinary obstruction.

Systemic Treatment for Advanced Hepatocellular Carcinoma.

BACKGROUND: Patients with advanced hepatocellular carcinoma (HCC) have a poor prognosis. First-line sorafenib has been the standard of care for a decade, but the treatment landscape is expanding. This review provides a practical overview of current and future systemic treatment options for advanced HCC and their place in clinical practice. SUMMARY: First-line sorafenib and lenvatinib have shown to improve the survival of patients with advanced HCC. In the second line, regorafenib provides benefit for patients who previously tolerated sorafenib. Anti-PD1 antibodies, nivolumab and pembrolizumab, recently became available for second-line use in the US. Ramucirumab (for patients with α-fetoprotein [AFP] levels ≥400) and cabozantinib present potential future second-line treatment options. Combinations of systemic and locoregional treatment, such as radiofrequency ablation or selective internal radiotherapy, require further research. Precision medicine has not yet been translated into clinical practice, as the most common driver mutations (TERT promoter, CTNNB1, TP53, and ARID1A mutations) have not yet been shown to be suitable therapeutic targets. However, our growing understanding of signaling pathways and efforts in drug development are expected to pave the way for precision medicine in HCC in the future. Evaluating the place for the current and novel systemic treatment options in clinical practice can be challenging due to the diverse toxicity profiles of the treatment options and characteristics of the patient population. Sorafenib data elucidate the effect patient characteristics (such as the performance score, Child-Pugh class, AFP, etiology of the underlying disease, and level of macrovascular invasion and extrahepatic spread) may have on outcomes in advanced stages. KEY MESSAGES: Lenvatinib is expected to join sorafenib as a preferred first-line treatment in advanced HCC. In the second line, the treatment of choice, regorafenib, is soon expected to be accompanied by cabozantinib and ramucirumab in patients with AFP ≥400 ng/mL, whereas nivolumab and pembrolizumab present second-line alternatives in the US.

Technology of irreversible electroporation and review of its clinical data on liver cancers.

INTRODUCTION: Irreversible electroporation (IRE) has developed as a novel percutaneous ablative technique over the past decade and its utility in the treatment of primary and metastatic liver disease has progressed rapidly. AREAS COVERED: After discussing the principles behind the technology and the practical steps in its use, this article offers a detailed analysis of the recent published work that evaluates its safety and efficacy. The strengths and weaknesses of other ablative techniques, including radiofrequency ablation, microwave ablation and cryoablation, are discussed in detail. Other aspects of IRE, including post-treatment clinical follow-up, expected imaging findings, and the most frequently encountered complications, are covered. Finally, the future of IRE is examined as it pertains to advancements in the treatment of hepatic malignancy. EXPERT COMMENTARY: The characteristics of IRE that make this technology uniquely suited for the treatment of liver tumors have allowed it to gain a significant foothold in interventional oncology. Continued development of IRE will lead to further advances in the management of previously untreatable liver cancers.

Success Rate and Complications of Sharp Recanalization for Treatment of Central Venous Occlusions.

PURPOSE: To evaluate success and safety of needle (sharp) recanalization as a method to re-establish access in patients with chronic central venous occlusions. MATERIALS AND METHODS: Thirty-nine consecutive patients who underwent this procedure were retrospectively reviewed to establish success rate and associated complications. In all cases, a 21- or 22-gauge needle was used to restore connection between two chronically occluded segments after conventional wire and catheter techniques had failed. The needle was guided toward a target placed through a separate access by fluoroscopic guidance. When successful, the procedure was completed by placing a catheter, ballooning the segment, and/or stenting. RESULTS: The procedure was successful in 37 of the 39 patients (95%). The vast majority of the treated lesions were in the SVC and/or right innominate vein. Occlusions ranged in length between 10 and 110 mm, and the average length of occluded venous segment was 40 mm in the treated group. There were four minor (SIR classification B) complications involving pain management after the procedure. There were two major (SIR classification D) complications both of which involved hemorrhage into the pericardium treated with covered stents (5.1%). CONCLUSIONS: Sharp recanalization is a viable procedure for patients who have exhausted standard wire and catheter techniques. The operator performing this procedure should be familiar with potential complications so that they can be addressed urgently if needed.

Predicting abdominal closure after component separation for complex ventral hernias: maximizing the use of preoperative computed tomography.

BACKGROUND: Component separation techniques (CSTs) have allowed for midline fascial reapproximation in large midline ventral hernias. In certain cases, however, fascial apposition is not feasible, resulting in a bridged repair that is suboptimal. Previous estimates on myofascial advancement are based on hernia location and do not take into account variability between patients. Examination of preoperative computed tomography (CT) may provide insight into these variabilities and may allow for prediction of abdominal closure with CST. STUDY DESIGN: A retrospective review was conducted of patients who underwent abdominal wall reconstruction from 2007 to 2012 with CST. Preoperative CT was obtained, and specific parameters were analyzed using image analysis software. Logistic regression was used to predict ideal operative closure. Multivariate analyses were adjusted for age and sex. An a priori value was set at P < 0.05. RESULTS: Fifty-four patients met the criteria and had preoperative CT available for analysis. Forty-eight patients had fascial reapproximation achieved, whereas 6 patients had a bridged repair. Age, sex, weight, and body mass index were similar between groups (P > 0.05). Significant differences were seen between groups in 3 variables: transverse defect size (19.8 vs 10 cm, P < 0.05), defect area (420 vs 184.2 cm, P < 0.05), and percent abdominal wall defect (18.9% vs 10.6%, P < 0.05). CONCLUSIONS: Preoperative determination of abdominal wall defect ratios and hernia defect areas may represent a more accurate method to predict abdominal wall closure after CST. Predicting midline approximation after CST is critical because outcomes after bridged repair can result in higher recurrence rates.

Computerized tomographic and magnetic resonance angiography for perforator-based free flaps: technical considerations.

Perforator-based free flaps rely on the appropriate dominant vessel supplying the vascular territory of the flap. Preoperative knowledge of the vascular anatomy can improve outcome and diminish surgical time. Several preoperative imaging techniques exist for surgical planning. Computed tomographic and magnetic resonance angiography are two emerging modalities that provide exceptional anatomic detail. Despite the growing utilization of cross-sectional imaging for preoperative planning, each modality has specific technical considerations that are necessary to consider in order to produce a quality study.

Cross-sectional, prospective study of MRI reproducibility in the assessment of plaque burden of the carotid arteries and aorta.

BACKGROUND: The reliability of imaging techniques to assess early atherosclerosis remains unclear. We did a cross-sectional, prospective study to test reproducibility of MRI when imaging arteries, to assess risk of cardiovascular disease and correlations with age and sex. METHODS: Between January 2003 and December 2006 we performed black-blood MRI of both common carotid arteries and the thoracic descending aorta in patients with cardiovascular risk factors who were referred from clinics in New York, NY, USA. Mean wall area, wall thickness, lumen area, total vessel area, and ratio of the mean wall area to the mean total vessel area (WA/TVA) were manually measured. Reproducibility within and between readers was tested on subsets of images from randomly chosen patients. RESULTS: MRI was performed on 300 patients. Intrareader reproducibility, assessed in images from 20 patients, was high for all parameters (intraclass correlation coefficients >0.8), except WA/TVA ratio in the descending aorta. The inter-reader reproducibility, assessed in images from 187 patients, was acceptable (intraclass correlation coefficients >0.7) for the mean wall, lumen, and total vessel areas. Values for all MRI parameters in all vessels increased with increasing age for both sexes (all P <0.0005) but were always significantly higher in men than in women, except for aortic mean wall thickness and WA/TVA ratio in the carotid arteries. Mean wall area values correlated well between the carotid arteries and aorta, reflecting the systemic nature of atherosclerosis. CONCLUSIONS: Our findings support MRI as a reproducible measurement of plaque burden and demonstrate the systemic distribution of atherosclerosis.

MRI estimation of total renal volume demonstrates significant association with healthy donor weight.

PURPOSE: The purpose of this study was to correlate total renal volume (TRV) calculations, obtained through the voxel-count method and ellipsoid formula with various physical characteristics. MATERIALS AND METHODS: MRI reports and physical examination from 210 healthy kidney donors (420 kidneys), on whom renal volumes were obtained using the voxel-count method, were retrospectively reviewed. These values along with ones obtained through a more traditional method (ellipsoid formula) were correlated with subject height, body weight, body mass index (BMI), and age. RESULTS: TRV correlated strongly with body weight (r=0.7) and to a lesser degree with height, age, or BMI (r=0.5, -0.2, 0.3, respectively). The left kidney volume was greater than the right, on average (p<0.001). The ellipsoid formula method over-estimated renal volume by 17% on average which was significant (p<0.001). CONCLUSIONS: Body weight was the physical characteristic which demonstrated the strongest correlation with renal volume in healthy subjects. Given this finding, a formula was derived for estimating the TRV for a given patient based on the his or her weight: TRV = 2.96 x weight (kg) + 113+/-64.

Phase II trial evaluating the clinical and biologic effects of bevacizumab in unresectable hepatocellular carcinoma.

PURPOSE: To determine the clinical and biologic effects of bevacizumab, an anti-vascular endothelial growth factor (VEGF) monoclonal antibody, in unresectable hepatocellular carcinoma (HCC). PATIENTS AND METHODS: Adults with organ-confined HCC, Eastern Cooperative Oncology Group performance status of 0 to 2, and compensated liver disease were eligible. Patients received bevacizumab 5 mg/kg (n = 12) or 10 mg/kg (n = 34) every 2 weeks until disease progression or treatment-limiting toxicity. The primary objective was to determine whether bevacizumab improved the 6-month progression-free survival (PFS) rate from 40% to 60%. Secondary end points included determining the effects of bevacizumab on arterial enhancement and on plasma cytokine levels and the capacity of patients' plasma to support angiogenesis via an in vitro assay. RESULTS: The study included 46 patients, of whom six had objective responses (13%; 95% CI, 3% to 23%), and 65% were progression free at 6 months. Median PFS time was 6.9 months (95% CI, 6.5 to 9.1 months); overall survival rate was 53% at 1 year, 28% at 2 years, and 23% at 3 years. Grade 3 to 4 adverse events included hypertension (15%) and thrombosis (6%, including 4% with arterial thrombosis). Grade 3 or higher hemorrhage occurred in 11% of patients, including one fatal variceal bleed. Bevacizumab was associated with significant reductions in tumor enhancement by dynamic contrast-enhanced magnetic resonance imaging and reductions in circulating VEGF-A and stromal-derived factor-1 levels. Functional angiogenic activity was associated with VEGF-A levels in patient plasma. CONCLUSION: We observed significant clinical and biologic activity for bevacizumab in nonmetastatic HCC and achieved the primary study end point. Serious bleeding complications occurred in 11% of patients. Further evaluation is warranted in carefully selected patients.

Time-resolved MR angiography for the classification of endoleaks after endovascular aneurysm repair.

PURPOSE: To evaluate the utility of time-resolved MR angiography (TR-MRA), compared with digital subtraction angiography (DSA), in the classification of endoleaks in patients who have undergone endovascular aneurysm repair (EVAR). MATERIALS AND METHODS: Thirty-one patients who had undergone EVAR to repair an abdominal aortic aneurysm were evaluated with both TR-MRA and DSA to determine endoleak etiology. The patient population consisted of 26 men and 5 women with a mean age of 78.5 years (range, 55-93 years). The mean time interval between TR-MRA and DSA was 1.5 weeks (range, 1-8 weeks). Endoleaks were classified as type II when enhancement of the external iliac vessels was observed before the appearance of the endoleak; otherwise the endoleak was classified as type I or III. The results of TR-MRA classification were compared with the reference gold standard, DSA. RESULTS: Agreement between TR-MRA and DSA regarding endoleak classification occurred in 30 of 31 cases (97%). Discordant classification occurred in a case in which a Type II endoleak was misclassified as a Type III due to failure to visualize a lumbar vessel. CONCLUSION: TR-MRA is highly effective in classifying endoleaks following EVAR when compared with DSA.

MDCT angiography of the renal arteries in patients with atherosclerotic renal artery stenosis: implications for renal artery stenting with distal protection.

OBJECTIVE: Use of distal protection in renal artery stenting entails overcoming challenges unique to renal artery anatomy. We used 3D image reconstruction to review high-spatial-resolution MDCT angiographic data to better characterize the anatomy of stenotic renal arteries. MATERIALS AND METHODS: A total of 218 abdominal MDCT angiograms from a single tertiary care referral center were reviewed. The subjects were 108 patients who had 127 arteries with more than 50% ostial atherosclerotic renal artery stenosis. Vessel analysis software was used to measure renal artery length, cross-sectional area, and maximum diameter. Differences between mean values for women and men and for left and right renal arteries were measured with a two-tailed Student's t test. RESULTS: Significant differences for men and women were found in average maximum cross-sectional area distal to the point of stenosis (0.3 +/- 0.19 vs 0.23 +/- 0.09 cm2, p = 0.006) and the corresponding maximum diameter (6.9 +/- 1.7 vs 6.1 +/- 1.1 cm2, p = 0.003). Average lengths of the main renal artery did not differ significantly for men and women. Differences for the left and right main renal arteries were found in minimum area (i.e., area of maximum stenosis, 0.08 +/- 0.04 vs 0.06 +/- 0.03 cm2, p = 0.03), area proximal to the bifurcation (0.26 +/- 0.11 cm2 vs 0.23 +/- 0.07 cm2, p = 0.02), and length (38.5 +/- 12.6 vs 48.7 +/- 16.2 mm, p = 0.0002). CONCLUSION: Significant anatomic differences exist between the left and right renal arteries, between the renal arteries in men and those in women, and from one person to the next. Many of these differences are relevant to the design and use of distal protection devices in stenting of the renal arteries.

MR angiography for patient surveillance after endovascular repair of abdominal aortic aneurysms.

OBJECTIVE: The objective of this article is to demonstrate how new imaging sequences and techniques allow characterization of postoperative complications after endovascular surgery and offer the physician more information for planning treatment than ever before. CONCLUSION: MR angiography is an excellent technique for the surveillance of patients after endovascular repair of abdominal aortic aneurysms because it is highly sensitive for the detection of postoperative complications. A thorough knowledge of the physical properties of the endovascular components is essential to choose the appropriate patients for this form of surveillance.

Hepatic imaging in the 21st century.

Imaging of the liver has progressed rapidly during the past decade with continued advancement of current ultrasound, computed tomography, and magnetic resonance imaging (MRI). Each modality not only has seen refinement enabling better anatomic characterization of disease but also has received strength from the addition of new techniques to its resources. New contrast agents have become available for all modalities and some agents, particularly for MRI, have opened the way for better functional assessment. MRI continues to see an elaboration of sequences (including spectroscopy and diffusion) that also open imaging to the microscopic structure of disease and normal function. The further development of workstations have improved both analysis and depiction of disease. In the 21st century imaging will continue to shift from a simple source of anatomic information to a more functional problem-solving tool.