Smallest Clinically Meaningful Improvement in Amputation-Related Pain and Brief Pain Inventory Scores as Defined by Patient Reports of Global Improvement After Cryoneurolysis: a Retrospective Analysis of a Randomized, Controlled Clinical Trial

BACKGROUND

The smallest meaningful improvement in pain scores (minimal clinically important difference [MCID]) after an analgesic intervention is essential information when both interpreting published data and designing a clinical trial. However, limited information is available for patients with chronic pain conditions, and what is published is derived from studies involving pharmacologic and psychological interventions. We here calculate these values based on data collected from 144 participants of a previously published multicenter clinical trial investigating the effects of a single treatment with percutaneous cryoneurolysis.

METHODS

In the original trial, we enrolled patients with a lower-limb amputation and established phantom pain. Each received a single-injection femoral and sciatic nerve block with lidocaine and was subsequently randomized to receive either ultrasound-guided percutaneous cryoneurolysis or sham treatment at these same locations. Investigators, participants, and clinical staff were masked to treatment group assignment with the exception of the treating physician performing the cryoneurolysis, who had no subsequent participant interaction. At both baseline and 4 months (primary end point), participants rated their phantom limb pain based on a numeric rating scale (NRS) and their interference of pain on physical and emotional functioning as measured with the Brief Pain Inventory's interference subscale. They subsequently qualitatively defined the change using the 7-point ordinal Patient Global Impression of Change (PGIC). The smallest clinically meaningful improvements in phantom limb pain and Brief Pain Inventory scores were calculated using an anchor-based method based on the PGIC.

RESULTS

The median (interquartile range [IQR]) phantom pain NRS (0-10) improvements at 4 months considered small, medium, and large were 1 [1-1], 3 [3-4], and 4 [3-6], respectively. The median improvements in the Brief Pain Inventory interference subscale (0-70) associated with a small, medium, and large analgesic changes were 16 [6-18], 24 [22-31], and 34 [22-46]. The proportions of patients that experienced PGIC ≥5 were 33% and 36% in the active and placebo groups, respectively. The relative risk of a patient experiencing PGIC ≥5 in the active group compared to the sham group with 95% confidence interval was 0.9 (0.6-1.4), P = .667.

CONCLUSIONS

Amputees with phantom limb pain treated with percutaneous cryoneurolysis rate analgesic improvements as clinically meaningful similar to pharmacologic treatments, although their MCID for the Brief Pain Inventory was somewhat larger than previously published values. This information on patient-defined clinically meaningful improvements will facilitate interpretation of available studies and guide future trial design.

Safety and Effectiveness of Stellate Ganglion Cryoablation in Complex Regional Pain Syndrome

This was a retrospective, observational, descriptive study to evaluate the safety and 6-month effectiveness of percutaneous cryoablation of the stellate ganglion for the treatment of complex regional pain syndrome (CRPS). Eight patients with CRPS diagnosed by Budapest criteria were treated with this procedure. CRPS symptom severity was assessed prior to the procedure and at 3-month intervals after the procedure using a novel CRPS scoring system-the Budapest score-created by the authors. The mean Budapest score prior to and 6 months (187 days, SD ± 43) after stellate ganglion cryoablation was 7.0 (SD ± 2.0) (n = 6) and 3.8 (SD ± 2.3) (n = 6), respectively, showing a decrease of 3.2 (SD ± 1.7) (n = 6; P = .006). There were no major adverse events due to the procedure, and there was only 1 minor adverse event. Stellate ganglion cryoablation is a feasible, safe, and minimally invasive procedure that may represent an efficacious adjunct treatment option for select patients with CRPS.

Relative Effects of Various Factors on Ice Ball Formation and Ablation Zone Size During Ultrasound-Guided Percutaneous Cryoneurolysis: A Laboratory Investigation to Inform Clinical Practice and Future Research

INTRODUCTION

Ultrasound-guided percutaneous cryoneurolysis provides analgesia using cold temperatures to reversibly ablate peripheral nerves. Cryoneurolysis probes pass a gas through a small internal annulus, rapidly lowering the pressure and temperature, forming an ice ball to envelope the target nerve. Analgesia is compromised if a nerve is inadequately frozen, and laboratory studies suggest that pain may be paradoxically induced with a magnitude and duration in proportion with the incomplete ablation. We therefore investigated the relative effects of various factors that may contribute to the size of the ice ball and the effective cryoneurolysis zone.

METHODS

A cryoprobe was inserted into a piece of meat, a gas was passed through for 2 min, and the resulting ice ball width (cross-section) and length (axis parallel to the probe) were measured using ultrasound, with the temperature evaluated in nine concentric locations concurrently.

RESULTS

The factor with the greatest influence on ice ball size was probe gauge: in all probe types, a change from 18 to 14 increased ice ball width, length, and volume by up to 70%, 113%, and 512% respectively, with minimum internal temperature decreasing as much as from -5 to -32 °C. In contrast, alternating the type of meat (chicken, beef, pork) and the shape of the probe tip (straight, coudé) affected ice ball dimensions to a negligible degree. The ice ball dimensions and the zone of adequate temperature drop were not always correlated, and, even within a visualized ice ball, the temperature was often inadequate to induce Wallerian degeneration.

CONCLUSIONS

Percutaneous probe design can significantly influence the effective cryoneurolysis zone; visualizing a nerve fully encompassed in an ice ball does not guarantee adequate treatment to induce the desired Wallerian degeneration because ice forms at temperatures between 0 and -20 °C, whereas only temperatures below -20 °C induce Wallerian degeneration. The correlation between temperatures in isolated pieces of meat and perfused human tissue remains unknown, and further research to evaluate these findings in situ appears highly warranted.

Ultrasound-guided Percutaneous Cryoneurolysis to Treat Chronic Postamputation Phantom Limb Pain: A Multicenter Randomized Controlled Trial

BACKGROUND

Postamputation phantom pain is notoriously persistent with few validated treatments. Cryoneurolysis involves the application of low temperatures to reversibly ablate peripheral nerves. The authors tested the hypothesis that a single cryoneurolysis treatment would decrease phantom pain 4 months later.

METHODS

The authors enrolled patients with a lower-limb amputation and established phantom pain. Each received a single-injection femoral and sciatic nerve block with lidocaine and was subsequently randomized to receive either ultrasound-guided percutaneous cryoneurolysis or sham treatment at these same locations. The primary outcome was the change in average phantom pain intensity between baseline and 4 months as measured with a numeric rating scale (0 to 10), after which an optional crossover treatment was offered. Investigators, participants, and clinical staff were masked to treatment group assignment with the exception of the treating physician performing the cryoneurolysis, who had no subsequent participant interaction.

RESULTS

Pretreatment phantom pain scores were similar in both groups, with a median [quartiles] of 5.0 [4.0, 6.0] for active treatment and 5.0 [4.0, 7.0] for sham. After 4 months, pain intensity decreased by 0.5 [-0.5, 3.0] in patients given cryoneurolysis (n = 71) versus 0 [0, 3] in patients given sham (n = 73), with an estimated difference (95% CI) of -0.1 (-1.0 to 0.7), P = 0.759. Following their statistical gatekeeping protocol, the authors did not make inferences or draw conclusions on secondary endpoints. One serious adverse event occurred after a protocol deviation in which a femoral nerve cryolesion was induced just below the inguinal ligament-instead of the sensory-only saphenous nerve-which resulted in quadriceps weakness, and possibly a fall and clavicle fracture.

CONCLUSIONS

Percutaneous cryoneurolysis did not decrease chronic lower extremity phantom limb pain 4 months after treatment. However, these results were based upon the authors' specific study protocol, and since the optimal cryoneurolysis treatment parameters such as freeze duration and anatomic treatment location remain unknown, further research is warranted.

EDITOR’S PERSPECTIVE

Percutaneous CT-Guided Cryoneurolysis of the Intercostobrachial Nerve for Management of Postmastectomy Pain Syndrome

PURPOSE

To evaluate the feasibility, safety, and efficacy of intercostobrachial nerve (ICBN) cryoneurolysis for pain control in patients with postmastectomy pain syndrome (PMPS).

MATERIALS AND METHODS

Fourteen patients with PMPS were prospectively enrolled into this clinical trial after a positive response to a diagnostic computed tomography (CT)-guided percutaneous block of the ICBN. Participants subsequently underwent CT-guided percutaneous cryoneurolysis of the same nerve and were observed on postprocedural Days 10, 90, and 180. Pain scores, quality-of-life measurements, and global impression of change values were recorded before the procedure and at each follow-up point using established validated outcome instruments.

RESULTS

Cryoneurolysis of the ICBN was technically successful in all 14 patients. The mean pain decreased significantly by 2.1 points at 10 days (P = .0451), by 2.4 points at 90 days (P = .0084), and by 2.9 points at 180 days (P = .0028) after cryoneurolysis. Pain interference with daily activities decreased significantly by 14.4 points after 10 days (P = .0161), by 16.2 points after 90 days (P = .0071), and by 20.7 points after 180 days (P = .0007). There were no procedure-related complications or adverse events.

CONCLUSIONS

Cryoneurolysis of the ICBN in patients with PMPS was technically feasible and safe and resulted in a significant decrease in postmastectomy pain for up to 6 months in this small cohort.

Agents Used for Nerve Blocks and Neurolysis

The recognition of pain and the treatments used for it are vital for all practitioners. Many types of pain can be treated in a locoregional fashion, which has significant implications not just for any individual patient but for society as a whole. These treatments are most effective when performed in a minimally invasive, image-guided fashion. Interventional radiologists should play a central role in providing these lifestyle-limiting treatments. This article describes the medications most typically used for spinal and extra-axial treatments in the management of patients in pain.

Review of Extraosseous Applications of Thermal Ablation in the Treatment of Moderate to Severe Large Joint Osteoarthritis

Osteoarthritis (OA) is the most common joint disease worldwide, leading to significant pain, restricted range of motion, and disability. A gap exists between short- and long-term symptom-relieving therapies. Although arthroplasty is an effective treatment for symptomatic end-stage disease, most patients ultimately do not receive a joint replacement due to suboptimal surgical qualifications, comorbidities, or an aversion to surgery. The lack of additional treatment options in this setting makes opioid agonists a commonly used pharmacologic agent, contributing to the addiction epidemic that greatly afflicts our communities. Cooled radiofrequency ablation (CRFA) has arisen as a treatment modality in the setting of moderate to severe OA among patients refractory to conservative management, generally showing greater efficacy compared with other existing strategies. This review focuses on the benefits of CRFA and its technical feasibility as a management option among patients experiencing debilitating large joint OA with limited clinical options.

Interventional Radiology Obesity Therapeutics: Proceedings from the Society of Interventional Radiology Foundation Research Consensus Panel

The Society of Interventional Radiology Foundation commissioned a Research Consensus Panel to establish a research agenda on "Obesity Therapeutics" in interventional radiology (IR). The meeting convened a multidisciplinary group of physicians and scientists with expertise in obesity therapeutics. The meeting was intended to review current evidence on obesity therapies, familiarize attendees with the regulatory evaluation process, and identify research deficiencies in IR bariatric interventions, with the goal of prioritizing future high-quality research that would move the field forward. The panelists agreed that a weight loss of >8%-10% from baseline at 6-12 months is a desirable therapeutic endpoint for future IR weight loss therapies. The final consensus on the highest priority research was to design a blinded randomized controlled trial of IR weight loss interventions versus sham control arms, with patients receiving behavioral therapy.

Cryoablation for Palliation of Painful Bone Metastases: The MOTION Multicenter Study

PURPOSE

To assess the clinical effectiveness of cryoablation for palliation of painful bone metastases.

MATERIALS AND METHODS

MOTION (Multicenter Study of Cryoablation for Palliation of Painful Bone Metastases) (ClinicalTrials.gov NCT02511678) was a multicenter, prospective, single-arm study of adults with metastatic bone disease who were not candidates for or had not benefited from standard therapy, that took place from February 2016 to March 2018. At baseline, participants rated their pain using the Brief Pain Inventory-Short Form (reference range from 0 to 10 points); those with moderate to severe pain, who had at least one metastatic candidate tumor for ablation, were included. The primary effectiveness endpoint was change in pain score from baseline to week 8. Participants were followed for 24 weeks after treatment. Statistical analyses included descriptive statistics and logistic regression to evaluate changes in pain score over the postprocedure follow-up period.

RESULTS

A total of 66 participants (mean age, 60.8 years ± 14.3 [standard deviation]; 35 [53.0%] men) were enrolled and received cryoablation; 65 completed follow-up. Mean change in pain score from baseline to week 8 was -2.61 points (95% CI: -3.45, -1.78). Mean pain scores improved by 2 points at week 1 and reached clinically meaningful levels (more than a 2-point decrease) after week 8; scores continued to improve throughout follow-up. Quality of life improved, opioid doses were stabilized, and functional status was maintained over 6 months. Serious adverse events occurred in three participants.

CONCLUSION

Cryoablation of metastatic bone tumors provided rapid and durable pain palliation, improved quality of life, and offered an alternative to opioids for pain control.Keywords: Ablation Techniques, Metastases, Pain Management, Radiation Therapy/OncologySupplemental material is available for this article.© RSNA, 2021.

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.

Interventional Cryoneurolysis: An Illustrative Approach

The application of advanced imaging guidance and the interventional radiology skill set has expanded the breadth of nerve and nerve plexus targets in the body for potential cryoneurolysis. Advancement of the basic science supporting cryoneurolysis has further solidified proceduralists' confidence and ability to select and manage patients clinically. As these procedures continue to evolve, a structured approach to the wide variety of indications is necessary.

Interventional Cryoneurolysis: What Is the Same, What Is Different, What Is New?

Cryoneurolysis is the deliberate application of cold temperatures to nerves for therapeutic purposes. The idea of treating pain with this technique is thousands of years old and has evolved over time through the application of surgical techniques, nerve stimulation and/or landmark guidance, and through device development. Recent integration of the interventional radiology skill set to this space has unlocked a myriad of opportunities-primarily through a unique ability to percutaneously access deep structures in the body with accuracy and precision, and the capacity to monitor ablation zones. Understanding of the specific neurohistological process that follows targeted cryoneurolysis leads to new options for treating patients in pain without drugs and opens doors for the potential modification of a wide array of disease states.

Percutaneous CT-Guided Cryovagotomy in Patients with Class I or Class II Obesity: A Pilot Trial

OBJECTIVE

This study evaluated the safety of percutaneous CT-guided cryoablation of the vagus nerve (percutaneous cryovagotomy) in participants with class I or class II obesity.

METHODS

The study was an open-label, single-group, prospective pilot investigation designed around safety-related stopping criteria. Twenty participants with 30 > BMI > 37 underwent percutaneous cryovagotomy with follow-up visits at day 7, 45, 90, and 180. Data related to adverse events, technical success, weight loss, quality of life, dietary intake, global impressions of hunger change, activity, and body composition were analyzed.

RESULTS

The procedural technical success rate was 100%. There were no adverse events in 19 participants who completed the trial. Ninety-five percent of patients reported decreased appetite following the procedure, and reductions in mean absolute weight and BMI were observed at all time points. The mean quality of life and activity scores improved from baseline to 6 months post procedure, and mean caloric intake and overall body fat decreased over the same period.

CONCLUSIONS

Percutaneous CT-guided cryovagotomy is feasible and was tolerated without complications or adverse events in this cohort. Quantitative preliminary data from this pilot investigation inform the design of a larger prospective randomized clinical trial.

Image-Guided Transarterial Directed Delivery of Human Mesenchymal Stem Cells for Targeted Gastrointestinal Therapies in a Swine Model

PURPOSE

To evaluate the feasibility of catheter-directed intra-arterial stem cell delivery of human mesenchymal stem cells (MSCs) to the small bowel in a porcine model.

MATERIALS AND METHODS

The cranial mesenteric artery of 6 Yucatan minipigs was selectively catheterized under fluoroscopic guidance following cut-down and carotid artery access. A proximal jejunal branch artery was selectively catheterized for directed delivery of embolic microspheres (100-300 μm) or MSCs (0.1-10 million cells). The pigs were euthanized after 4 hours and specimens collected from the proximal duodenum and the targeted segment of the jejunum. The Chiu/Park system for scoring intestinal ischemia was used to compare hematoxylin and eosin-stained sections of jejunum and duodenum.

RESULTS

Successful delivery of microspheres or MSCs in a proximal jejunal branch artery of the cranial mesenteric artery was achieved in all subjects. Radiopaque microspheres and post-delivery angiographic evidence of stasis in the targeted vessels were observed on fluoroscopy after delivery of embolics. Preserved blood flow was observed after MSC delivery in the targeted vessel. The Chiu/Park score for intestinal ischemia in the targeted proximal jejunal segments were similar for microspheres (4, 4; n = 2) and MSCs (4, 4, 4, 3; n = 4), indicating moderate ischemic effects that were greater than for control duodenal tissue (3, 1; 0, 0, 3, 3).

CONCLUSIONS

Selective arteriographic deployment of MSCs in swine is feasible for study of directed intestinal stem cell delivery. In this study, directed therapy resulted in intestinal ischemia.

Obstruction of the Biliary and Urinary System

Biliary and urinary obstructions can be managed endoscopically or cystoscopically, surgically or by percutansous intervention or drainage. If the obtructed system is infected, emergent decompression is needed. Early recognition and treatment is paramount in both conditions. Acute cholangitis can present many different ways, from mild symptoms to fulminant sepsis. It is usually a result of ascending bacterial colonization and biliary obstruction resulting in bacterial overgrowth. Therefore, those patients with recent biliary instrumentation or previous biliary modification are at higher risk. Charcot's triad of fever, right upper quadrant abdominal pain, and jaundice is only seen in 50%-70% of patients. Fever is seen in over 90% of cases, pain is seen in 70% of cases, and jaundice is seen in 60% of cases. Altered mental status and hypotension are associated with severe cases. All 5 symptoms of fever, right upper quadrant abdominal pain, jaundice, altered mental status, and hypotension are referred to as Reynold's Pentad. Acute pyonephrosis can also present many different ways, from minimal symptoms to fulminant sepsis. Fever, chills, and flank pain are the classic symptoms, although some patients may be relatively asymptomatic. Pyonephrosis may present with a classic triad of fever, flank pain, and hydronephrosis, or simply hydronephrosis and sepsis. Pyonephrosis usually occurs as a result of urinary obstruction with either an ascending infection of the urinary tract or hematogenous spread of a bacterial pathogen as the culprit. Up to 75% of cases are related to urinary stone disease. Patients are at increased risk for pyonephrosis when they haven anatomic urinary tract obstruction, certain chronic diseases (diabetes meliitus and AIDS), or are immunosuppressed due to immunodeficiency or medications, (chronic steroid therapy).

Percutaneous Image-Guided Cryoablation for the Treatment of Phantom Limb Pain in Amputees: A Pilot Study

PURPOSE

To prospectively evaluate percutaneous image-guided nerve cryoablation for treatment of refractory phantom limb pain (PLP) in a pilot cohort for purposes of deriving parameters to design a larger, randomized, parallel-armed, controlled trial.

MATERIALS AND METHODS

From January 2015 to January 2016, 21 patients with refractory PLP underwent image-guided percutaneous cryoneurolysis procedures. Visual analog scale scores were documented at baseline and 7, 45, and 180 days after the procedure. Responses to a modified Roland Morris Disability Questionnaire were documented at baseline and 7 and 45 days after the procedure.

RESULTS

Technical success rate of the procedures was 100%. There were 6 (29%) minor procedure-related complications. Disability scores decreased from a baseline mean of 11.3 to 3.3 at 45-day follow-up (95% confidence interval 5.8, 10.3; P < .0001). Pain intensity scores decreased from a baseline mean of 6.2 to 2.0 at long-term follow-up (95% confidence interval 2.8, 5.6; P < .0001).

CONCLUSIONS

Image-guided percutaneous nerve cryoablation is feasible and safe and may represent a new efficacious therapeutic option for patients with phantom pains related to limb loss.

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.

Inactivation of Bacteria on Explanted Dialysis Catheter Lumens with Fiber Optically Delivered Ultraviolet Light

PURPOSE

To evaluate the germicidal effect of fiber optically delivered ultraviolet (UV) light on colonized explanted dialysis catheters.

MATERIALS AND METHODS

Explanted dialysis catheters were screened for intraluminal colonization by culturing 1 mL of a saline flush. Catheters growing >10 colony-forming units were treated with doses of fiber optically delivered UV light (range, 40-1,300 mJ/cm2). For each UV-treated catheter, an unexposed segment was first cut and set aside as a control sample. A sterile optical fiber was inserted into the catheter hub and advanced to the catheter tip. The fiber was slowly withdrawn at a constant rate while exposing the inner lumen to UV light. A second UV-exposed segment was then removed. The UV-exposed and control segments were split and sonicated to remove the adherent bacteria. The bacteria were counted and identified.

RESULTS

There were 14 colonized catheters treated with UV light. The catheters were primarily colonized with coagulase-negative staphylococci (60%) and Staphylococcus aureus (33%). There was a significant reduction in viable bacteria between the UV-treated versus untreated segments of each infected catheter (P = .04). In the seven treated catheters with >100,000 colony-forming units per cm2 of luminal surface area, there was a >99.5% reduction of viable bacteria in all UV-exposed samples, with no residual viable bacteria in four of seven (57%) of the samples.

CONCLUSIONS

This study demonstrates the technical feasibility and benchtop efficacy of using fiber optics to deliver UV light into the lumen of a colonized dialysis catheter and inactivating bacteria on the intraluminal surface.

Percutaneous CT-guided cryoablation for the treatment of refractory pudendal neuralgia

PURPOSE

To evaluate the safety and efficacy of percutaneous CT-guided cryoablation of the pudendal nerve for the treatment of refractory pudendal neuralgia.

MATERIALS AND METHODS

Eleven patients were selected to undergo percutaneous CT-guided cryoablation of the pudendal nerve based on established diagnostic criteria. Brief Pain Inventory questionnaires were administered prior to the procedure, during the immediate 24 h post procedure, and 45 days and 6 months following the procedure.

RESULTS

Prior to treatment, the average level of pain on a scale from 0 (no pain) to 10 (worst pain imaginable) was 7.6, with pain described as "burning" (80%), "pulling" (37.5%), "crushing" (50%), "pressure" (84.5%), "throbbing" (50%), "knife-life" (52%), and "other" (60%). At 24 h, 45 days, and 6 months post-treatment, pain intensity dropped to 2.6, 3.5, and 3.1, respectively (p < 0.005). There were no procedure-related complications.

CONCLUSIONS

CT-guided percutaneous cryoablation may represent a safe and efficacious option for selected patients with refractory pudendal neuralgia.

Image-guided cryoablation for the treatment of painful musculoskeletal metastatic disease: a single-center experience

PURPOSE

The role of image-guided thermal ablation techniques for the nonoperative local management of painful osseous metastatic disease has expanded during recent years, and several advantages of cryoablation in this setting have emerged. The purpose of this study is to retrospectively evaluate and report a single-center experience of CT-guided percutaneous cryoablation in the setting of painful musculoskeletal metastatic disease.

METHODS

This study was approved by the institutional review board and is compliant with the Health Insurance Portability and Accountability Act. Electronic medical records of all patients who underwent percutaneous image-guided palliative cryoablation at our institution were reviewed (n = 61). An intent-to-treat analysis was performed. Records were reviewed for demographic data and anatomical data, primary tumor type, procedure details, and outcome-including change in analgesic requirements (expressed as morphine equivalent dosages), pain scores (utilizing the clinically implemented visual analog scale), subsequent therapies (including radiation and/or surgery), and complications during the 24 h following the procedure and at 3 months. Patients were excluded (n = 7) if data were not retrospectively identifiable at the defined time points.

RESULTS

Fifty-four tumors were ablated in 50 patients. There were statistically significant decreases in the median VAS score and narcotic usage at both 24 h and 3 months (p < 0.000). Six patients (11%) incurred complications related to their therapy. Two patients had no relief at 24 h, of which both reported worsened pain at 3 months. One patient had initial relief but symptom recurrence at 3 months. Four patients went on to have radiation therapy of the ablation site at some point following the procedure.

CONCLUSIONS

CT-guided cryoablation is a safe, effective, reproducible procedural option for the nonoperative local treatment of painful musculoskeletal metastatic disease.

Incidence of hypercoagulable events after image-guided percutaneous cryoablation of renal tumors: a single-center experience

PURPOSE

To identify retrospectively hypercoagulable events that occurred over time in patients who underwent image-guided percutaneous renal cryoablation and compare the incidence with a cohort of patients who underwent surgical partial nephrectomy (PN) during the same time period.

MATERIALS AND METHODS

An electronic medical record database was queried for patients who underwent percutaneous image-guided renal mass cryoablation or PN between September 2006 and June 2012. Records were examined for thrombotic events during the year following the procedure in each group. Incidence rates, Kaplan-Meier estimates, and patient demographic variables were compared using the stratified log-rank test and t test for independent samples.

RESULTS

The study comprised 114 cryoablation cases. The cumulative incidence of thrombotic events after 1 year was 4.39%. The incidence per 100 person-years was 4.84. There were 105 PN cases. The cumulative incidence of thrombotic events after 1 year was 1.0%. The incidence per 100 person-years was 1.14. The person-time incidence rate difference for these two groups did not reach statistical significance (P = .0894).

CONCLUSIONS

The incidence of thrombotic events in patients who underwent percutaneous renal cryoablation in this study was not significantly different than a comparable cohort who underwent surgical PN during the same time period.

Percutaneous image-guided delivery for the transplantation of mesenchymal stem cells in the setting of degenerated intervertebral discs

PURPOSE

The delivery of mesenchymal stem cells (MSCs) to their site of action has remained a technical hurdle for clinical researchers in the expanding field of stem cell-based therapy. The purpose of this study was to test the feasibility of percutaneous image-guided needle delivery of bone marrow-derived human MSCs (hMSCs) to degenerated intervertebral discs (IVDs) in a preclinical model and to assess the containment of these cells within the IVDs.

MATERIALS AND METHODS

Degeneration was induced in the lumbar IVDs of four 28-35-kg female pigs. Approximately 100,000 iodine-124 2'-fluoro-2'-deoxy-1β-D-arabinofuranosyl-5-iodouracil-labeled hMSCs were delivered under fluoroscopic guidance to one of the affected discs in each of the animals. The remaining levels served as internal controls. The animals were imaged by computed tomography (CT) and positron emission tomography (PET) immediately after delivery and 3 days after the procedure. Fifteen days after transplantation, immunohistochemical staining was performed on harvested discs to confirm the presence of delivered hMSCs.

RESULTS

After refinement of the technique, PET-CT images on the day of cell transplantation showed initial deposition of the delivered radiolabeled MSCs to the IVD. An additional PET-CT study obtained 3 days later confirmed persistence and containment of activity in the IVD. Findings of histologic evaluation for the presence of human Alu sequences were positive in the treated discs and negative in the controls.

CONCLUSIONS

Image-guided needle delivery of MSCs for treatment of degenerated IVDs is feasible as demonstrated in this preclinical model. Trials of this minimally invasive technique in humans are warranted.

Cryoablation vs. radiofrequency ablation for small renal masses

RATIONALE AND OBJECTIVES

Cancer of the kidney is the third most common cancer of the urinary tract, and renal cell carcinoma is the most lethal of all genitourinary tumors. The incidental discovery of renal cell carcinoma has increased with increased use of cross-sectional imaging. Concomitantly, minimally invasive ablative technologies, including image-guided cryoablation, radiofrequency ablation, and others, have evolved as therapeutic options for small renal masses.

MATERIALS AND METHODS

Between 2006 and 2009, 111 patients (age range, 31-91 years; mean age, 70 years) underwent percutaneous computed tomography-guided thermal ablation for suspected renal cell carcinoma at two major academic centers. Outcomes data were retrospectively collected and analyzed to compare recurrence rates for patients undergoing radiofrequency ablation (n = 41) versus cryoablation (n = 70).

RESULTS

There were four cases of suspicious enhancement on follow-up computed tomography or magnetic resonance imaging in each group, with cumulative imaging recurrence rates of 11% and 7% for radiofrequency ablation and cryoablation, respectively. Log rank test analysis revealed no significant difference between rates of imaging recurrence between the two groups (P = .6044).

CONCLUSIONS

These results suggest that the use of cryoablative technology will result in similar outcomes compared with radiofrequency ablation.

CT pulmonary angiography: a comparative analysis of the utilization patterns in emergency department and hospitalized patients between 1998 and 2003

OBJECTIVE

The purpose of our study was to objectively examine the temporal utilization patterns of CT pulmonary angiography in emergency department and hospitalized patients in an academic tertiary care center.

SUBJECTS AND METHODS

Patients who underwent CT examination for suspected pulmonary embolism either through our emergency department or as inpatients during a recent 9-month interval were identified. The absolute number of studies and incidence of positive results and ancillary findings were compared with similar data published from our institution during the corresponding 9-month interval in 1997-1998.

RESULTS

The overall number of patients imaged for pulmonary embolism was significantly greater in the 2002-2003 period than in the 1997-1998 period (homogeneity of rates = 88.45, p < 0.0001). The absolute number of scans obtained was significantly greater in both the emergency department (chi(2) = 167.03, p < 0.0001) and inpatient (chi(2) = 210.62, p < 0.0001) groups in the more recent population. Significantly fewer ancillary findings were reported in both the emergency department (chi(2) = 5.93, p = 0.019) and inpatient (chi(2) = 6.03, p = 0.015) groups in the more recent population. The incidence of CT-detected pulmonary embolism was significantly less in both the emergency department (chi(2) = 34.26, p < 0.0001) and inpatient (chi(2) = 8.52, p < 0.01) groups in the more recent population. This decrease in the incidence of scans with positive findings for pulmonary embolism over time was significantly greater in the emergency department group than the inpatient group (homogeneity of odds = 0.003, p < 0.007).

CONCLUSION

The evolution of CT pulmonary angiography utilization has led to a significant increase in the number of patients being imaged for pulmonary embolism with a coincident significant decrease in the rates of CT-detected pulmonary embolism and ancillary findings both in emergency department and hospitalized patients.

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.