Image-Guided Percutaneous Ablation for Primary and Metastatic Tumors

Image-guided percutaneous ablation methods have been further developed during the recent two decades and have transformed the minimally invasive and precision features of treatment options targeting primary and metastatic tumors. They work by percutaneously introducing applicators to precisely destroy a tumor and offer much lower risks than conventional methods. There are usually shorter recovery periods, less bleeding, and more preservation of organ parenchyma, expanding the treatment options of patients with cancer who may not be eligible for resection. Image-guided ablation techniques are currently utilized for the treatment of primary and metastatic tumors in various organs including the liver, pancreas, kidneys, thyroid and parathyroid, prostate, lung, bone, and soft tissue. This article provides a brief review of the various imaging modalities and available ablation techniques and discusses their applications and associated complications in various organs.

Percutaneous cryoanalgesia for pain palliation: Current status and future trends

Cryoanalgesia, otherwise termed cryoneurolysis, refers to application of extreme cold upon peripheral nerves for palliation of pain associated to nerve lesions or biomechanical syndromes of neoplastic and non-neoplastic substrate. Application of cryoanalgesia initiates a cascade of pathophysiologic events interrupting nerve conduction of painful stimuli without irreversible nerve damage. Cryoanalgesia is considered a safe procedure with minimal risk of complications when performed with percutaneous approaches under imaging guidance. In the era of an opioid overdose crisis, cryoanalgesia can be proposed as an alternative aiming at controlling pain and improving life quality. Imaging guidance has substituted open surgical and nerve stimulation approaches in nerve identification, significantly contributing to the minimally invasive character of percutaneous approaches. Ultrasound or computed tomography can serve as low cost, ideal guiding techniques due to their abilities for precise anatomic delineation, high spatial resolution and good tissue contrast. The purpose of this review is to become familiar with the most common imaging guided percutaneous cryoanalgesia indications, to learn about different technical considerations during performance providing the current evidence. Controversies concerning products will be addressed.

Percutaneous CT-Guided Cryoablation of the Bilateral Pudendal Nerves for Palliation of Intractable Pain Related to Pelvic Neoplasms

Objectives:

The purpose of this report is to describe the effect of computed tomography–guided bilateral pudendal nerve cryoablations on pain and time to discharge in the setting of acute hospitalizations secondary to refractory pelvic pain from cancer.

Methods:

Investigators queried the medical record for patients who underwent pudendal nerve cryoablation using the Category III Current Procedural Technology code assignment 0442T or Category I code 64640 for cases prior to 2015. The resulting list was reviewed, and procedures performed on inpatients for intractable pelvic pain related to neoplasm were selected. The final cohort was then analyzed with regard to patient demographics, procedure details, technical success, safety, pain scores, and time to discharge.

Results:

Ten patients underwent cryoablation by 3 operators for palliation of painful pelvic neoplasms between June 2014 and January 2019. All probes were satisfactorily positioned and freeze cycles undertaken without difficulty. There were no procedure-related complications or adverse events. The mean difference in pre- and posttreatment worst pain scores was significant (n = 5.20, P = .003). The mean time to discharge following the procedure was 2.3 days.

Conclusion:

Computed tomography–guided percutaneous cryoablation of the bilateral pudendal nerves may represent a viable option in the setting of acute hospitalization secondary to intractable pain in patients with pelvic neoplasms.

Interventional stem cell therapy

The ability to deliver cells in appropriate doses to their targeted site of action is a well-known obstacle to optimising stem cell therapy. Systemic administration of cells results in pulmonary "trapping," which significantly decreases the number of available circulating cells to impact underlying disorders. Directed delivery of stem cells in interventional radiology may provide an additional option for bypassing the lungs, as well as introduce novel potential avenues for decreasing doses required to effect cellular therapy, efficiently obtain local paracrine effects, and/or to simplify targeting strategies.

Coblation for metastatic vertebral disease

PURPOSE

Plasma-mediated radiofrequency ablation (coblation) creates a cavity for directed polymethylmethacrylate deposition through molecular dissociation, providing a safe and efficacious cementoplasty for patients with high-risk, painful vertebral body metastatic disease. The purpose of this study was to retrospectively review and report details regarding the feasibility, safety, and efficacy of coblation and cementoplasty for treating painful advanced vertebral body metastatic disease.

MATERIALS AND METHODS

Fifteen patients with painful metastatic vertebral body fractures with a posterior cortical defect and/or epidural tumor extension underwent percutaneous coblation and cementoplasty. Each patient's medical record was reviewed for technical success, imaging outcome, complications, and palliative effect.

RESULTS

Of the 15 cases, 14 were completed successfully. Postprocedure imaging studies demonstrated adequate cement deposition within the targeted vertebral body without cement extravasation or fracture progression during the 1-3 months follow-up period. Pain relief was achieved in all patients, and no neurological damage was reported (mean follow-up, 141.1 ± 132.5 days).

CONCLUSION

Percutaneous image-guided coblation-mediated cavity creation prior to vertebroplasty allows for safe, efficacious cement deposition in patients with metastatic foci. Future studies prospectively comparing this procedure with other standard-of-care regimens are warranted.

Effect of the time to intervention on the outcome of thrombosed dialysis access grafts managed percutaneously

PURPOSE

We aimed to investigate the effect of the time interval from the clinical presentation of a thrombosed dialysis access graft to intervention on procedure success.

MATERIALS AND METHODS

Records from two academic institutions for patients who underwent percutaneous thrombectomy of occluded surgical hemodialysis graft access sites in interventional radiology from 2006 to 2011 were reviewed retrospectively. The following data were recorded: gender, age, time and date of the initial request for a thrombectomy and the procedure, age of the surgical access, angiographic outcome, and clinical outcome (successful or unsuccessful postinterventional dialysis). Univariate and multivariate logistic regression were used to evaluate whether the time to intervention significantly affected the study endpoint.

RESULTS

In total, 268 percutaneous thrombectomies were performed in 139 patients. Of these 224 (83.5%) were categorized as successful and 44 (16.4%) as unsuccessful. The time to intervention was 19.9±30.1 vs. 22±35 hours for successful and unsuccessful procedures, respectively. The difference between the two was not significant, and there were also no significant differences in covariate distributions between successful and unsuccessful outcomes.

CONCLUSION

During the first 72 hours following clinical presentation of a thrombosed dialysis access graft, time to intervention may be considered independent of procedure outcome.

The effect of single-detector CT versus MDCT on clinical outcomes in patients with suspected acute pulmonary embolism and negative results on CT pulmonary angiography

OBJECTIVE

We sought to compare the clinical outcomes of patients in whom pulmonary embolism (PE) has been ruled out with single-detector CT versus MDCT, given the improved visualization of subsegmental clots with the latter and the recent increase in use of CT for evaluation of PE.

SUBJECTS AND METHODS

Two cohorts of patients undergoing CT for suspected PE with either single-detector CT (3-mm collimation and pitch of 1.7) or MDCT (2-mm collimation and pitch of 1) scanners were prospectively observed and compared using predefined criteria for evidence of subsequent thromboembolic disease during the 6 months after the acquisition of their initial scan.

RESULTS

Ninety-eight patients were scanned using a single-detector CT scanner. Of these, none had evidence of subsequent PE or deep venous thrombosis (DVT), and six (6.1%) died of unrelated causes. Of the 100 patients scanned using an MDCT scanner, one (1.0%) had a subsequent nonfatal PE 2 months after the initial scanning, one (1.0%) had DVT 1 month after the initial scanning, and eight (8.0%) died of unrelated causes. No significant difference was found in either the probability of subsequent thromboembolic events (chi(2) = 0.3183, degrees of freedom [df] = 1, p = 1) or frequency of unrelated deaths (chi(2) = 0.2655, df = 1, p = 0.7829) between patients scanned using single-detector CT or MDCT protocols.

CONCLUSION

Our results show that patients with suspected acute PE and negative CT results have acceptable clinical outcomes in the absence of anticoagulation treatment up to 6 months after acquisition of their initial scan. Furthermore, we found that the increased visualization of smaller, more peripheral arteries afforded by multislice technology did not affect clinical outcome.

Variable diagnostic approach to suspected pulmonary embolism in the ED of a major academic tertiary care center

The purpose of this study is to retrospectively examine the patterns of diagnostic modality utilization in the setting of suspected acute pulmonary embolism (PE) by physicians in the emergency department (ED) of a major academic tertiary care center. All patients (n=180) with a hospital discharge diagnosis of PE that were admitted through the ED during 1997 to 1999 were included. Overall test frequency and distribution, ancillary testing used when the initial ventilation-perfusion (V/Q) scan or spiral computed tomography (sCT) angiogram was nondiagnostic, concordance of V/Q and sCT, and sensitivities of D-dimer assays, arterial blood gas analysis, and deep venous imaging were assessed. There was a wide discrepancy in practice, most pronounced when first-line radiological studies were nondiagnostic. There was a poor correlation of PE detection between sCT and V/Q. D-dimer assay, arterial blood gas analysis, and deep venous imaging are insensitive tests for PE, and "gold standard" pulmonary angiography is rarely used.

Patterns of immune responses evoked by allogeneic hepatocytes: evidence for independent co-dominant roles for CD4+ and CD8+ T-cell responses in acute rejection

INTRODUCTION

This is the first in a series of reports that characterizes immune responses evoked by allogeneic hepatocytes using a functional model of hepatocyte transplantation in mice.

METHODS

"Donor" hepatocytes expressing the transgene human alpha-1-antitrypsin (hA1AT-FVB/N, H2q) were transplanted into C57BL/6 (H2b) or MHC II knockout (H2b) hosts treated with anti-CD4, anti-CD8, or a combination of anti-CD4 and anti-CD8 monoclonal antibodies (mAbs). Hepatocyte rejection was determined as a loss of circulating ELISA-detectable transgene product (hA1AT). In addition, some C57BL/6 mice underwent transplantation with FVB/N heterotopic cardiac allografts and were treated with anti-CD4 mAb. Cardiac allograft rejection was determined by palpation. Graft recipients were tested for donor-reactive alloantibodies and donor-reactive delayed-type hypersensitivity (DTH) responses.

RESULTS

The median survival time (MST) of allogeneic hepatocytes in normal C57BL/6 mice was 10 days (no treatment), 10 days (anti-CD4 mAb), 14 days (anti-CD8 mAb), and 35 days (anti-CD4 and anti-CD8 mAbs). The MST of hepatocytes in B6 MHC class II knockout mice was 10 days (no treatment) and 21 days (anti-CD8 mAb). The MST of cardiac allografts was 11 days (no treatment) and >100 days (anti-CD4 mAb). Donor-reactive DTH responses were readily detected in both untreated and mAb-treated recipients. Donor-reactive alloantibody was barely detectable in untreated hosts.

CONCLUSIONS

These studies demonstrate that allogeneic hepatocytes are highly immunogenic and stimulate strong cell-mediated immune responses by both CD4+ and CD8+ T cells, even when treated with agents that can cause acceptance of cardiac allografts. Indeed, CD4+ or CD8+ T cells seem to independently cause hepatocellular allograft rejection. Allogeneic hepatocytes evoked strong donor-reactive DTH responses but were poor stimuli for donor-reactive antibody production. This is an unusual pattern of immune reactivity in allograft recipients.