Ablation of Primary and Recurrent Thyroid Cancer: Current and Future Perspectives.

Thyroid cancer is the most common endocrine malignancy, and its incidence is increasing, driven in part by the advent of ultrasound, and subsequent increased detection of small, early thyroid cancers. Yet even for small tumors, thyroidectomy with lymph node dissection remains standard of care. Specific to well-differentiated thyroid cancer, surgery has come under scrutiny as a possible overtreatment, in light of stable and favorable survival rates even as guidelines have allowed fewer radical resections and lymph node dissections over time. Moreover, thyroid cancer unfortunately has a known recurrence rate regardless of therapy, and surgical re-intervention for local structural recurrence is eventually limited by scar. Radioactive iodine therapy, another accepted treatment, is minimally invasive but can only treat patients with iodine-avid tumors. For all of these reasons, image-guided thermal ablation has emerged as a valuable complementary tool as a thyroid-sparing, parathyroid-sparing, voice-sparing, repeatable, minimally invasive outpatient focal therapy for both primary and recurrent well-differentiated thyroid cancers. However, the data are still evolving, and this represents a new patient cohort for some interventional radiologists. Therefore, the goal of this review is to discuss the technique and evidence for ablation of patients with thyroid cancer.

Long term impact of transjugular intrahepatic portosystemic shunt (TIPS) creation on hepatic morphology.

PURPOSE: The purpose of this study was to evaluate long-term morphologic changes occurring in the liver after TIPS creation with correlation with hepatic function to gain insight on the physiologic impact of TIPS on the liver. METHODS: This retrospective study included patients who underwent TIPS creation between 2005 and 2022 and had contrasted CT or MRI studies prior to and between 1 and 2 years post procedure. Strict exclusion criteria were applied to avoid confounding. Parenchymal volume and vessel measurements were assessed on the pre- and post-TIPS CT or MRI and MELD scores calculated. RESULTS: Of 580 patients undergoing TIPS creation, 65 patients (mean age, 55 years; 36 males) had pre-TIPS and post-TIPS imaging meeting inclusion criteria at median 16.5 months. After TIPS, the mean MELD score increased (12.9 to 15.4; p = 0.008) and total liver volume decreased (1730 to 1432 mL; p < 0.001). However, the magnitude of volume change did not correlate with MELD change. Neither portosystemic gradient nor TIPS laterality correlated with total or lobar hepatic volume changes or MELD changes. The main portal vein diameter increased (15.0 to 18.7 mm; p < 0.001). Thrombosis of the hepatic vein used for TIPS creation resulted in a mean increase in MELD of +4.1 compared to -2.1 in patients who had a patent and normal hepatic vein (p = 0.007). CONCLUSIONS: Given lack of correlation between portosystemic gradient, hepatic atrophy, hepatic function, and TIPS laterality, the alterations in portal flow dynamics after TIPS may not be impactful to hepatic function. However, hepatic vein patency after TIPS correlated with improved hepatic function.

Determining the Relationship between Delivery Parameters and Ablation Distribution for Novel Gel Ethanol Percutaneous Therapy in Ex Vivo Swine Liver.

Ethyl cellulose-ethanol (ECE) is emerging as a promising formulation for ablative injections, with more controllable injection distributions than those from traditional liquid ethanol. This study evaluates the influence of salient injection parameters on forces needed for infusion, depot volume, retention, and shape in a large animal model relevant to human applications. Experiments were conducted to investigate how infusion volume (0.5 mL to 2.5 mL), ECE concentration (6% or 12%), needle gauge (22 G or 27 G), and infusion rate (10 mL/h) impacted the force of infusion into air using a load cell. These parameters, with the addition of manual infusion, were investigated to elucidate their influence on depot volume, retention, and shape (aspect ratio), measured using CT imaging, in an ex vivo swine liver model. Force during injection increased significantly for 12% compared to 6% ECE and for 27 G needles compared to 22 G. Force variability increased with higher ECE concentration and smaller needle diameter. As infusion volume increased, 12% ECE achieved superior depot volume compared to 6% ECE. For all infusion volumes, 12% ECE achieved superior retention compared to 6% ECE. Needle gauge and infusion rate had little influence on the observed depot volume or retention; however, the smaller needles resulted in higher variability in depot shape for 12% ECE. These results help us understand the multivariate nature of injection performance, informing injection protocol designs for ablations using gel ethanol and infusion, with volumes relevant to human applications.

Computed Tomography Volumetry of Bone Cement: Retrospective Blinded Validation of Commercially Available Semi-automated Edge Detection Software.

OBJECTIVE: Cement volumes are increasingly linked to orthopedic oncology and neurosurgical outcomes (construct durability, adjacent fracture), but manual cement volumetry remains time prohibitive. The authors aim to report performance of PACS-integrated volumetric software specifically for barium-enhanced polymethylmethacrylate cement. METHODS: Institutional review board-approved single-institution retrospective review of patients from 2019-2022 undergoing kyphoplasty for pathological compression fractures with a quantitative cement infuser providing true cement volume. An operator blinded to true cement volumes retrospectively performed software-assisted volumetry on follow-up computed tomography scans. RESULTS: Included were 91 kyphoplasty levels in 56 patients: mean age, 62 years (range, 34-85 years), 73% female. True cement volume (available for 44 of 66 procedures) was mean 4.5 mL per level (range, 1.2-15.6 mL). Measured cement volume (available for all procedures) yielded a mean of 6.1 mL per level (range, 1.5-27.9 mL). For the 57 levels (39 patients) where both true and measured cement volumes were available, linear regression intercept and slope were 1.46 (95% CI = 0.97-1.95, P < 0.001) and 0.52 (CI = 0.47-0.57, P < 0.001), respectively, suggesting measured volume averaged 1.46 mL greater than true volume, with each additional milliliter of measured volume corresponding to approximately 0.52 mL of true volume. There was no significant difference in the relationship between estimated and actual cement volume in thoracic levels (intercept = -0.24, CI = -1.13 to 0.66, P = 0.61; slope = 0.03, CI = -0.14 to 0.19, P = 0.73) compared with lumbar levels. The goodness-of-fit of the regression model was strong ( R2 = 0.81). Discrepancies ranged from 90% underestimation to 52% overestimation; average, 17% overestimation. CONCLUSIONS: Semi-automated volumetry maintained a strong correlation with true volumes across the thoracic and lumbar curvatures, overestimating cement volume by a mean of 17% or 1.46 mL.

Vortex-assisted resin y90 delivery via 175 cm Truselect microcatheter: case factors for high residual despite double-flush protocol.

PURPOSE: To report efficiency of resin y90 delivery using SIROS via 175 cm TruSelect microcatheter with double-flush protocol (40 ml dextrose total). METHODS: IRB-approved retrospective review of all patients undergoing SIROS injection of y90 Sir-Spheres via TruSelect from 2019 through 2022 at one quaternary-care academic institution, including medical records. RESULTS: Included were 48 infusions in 25 patients across 11 cancer histologies. Mean planned, delivered, and residual activities were 28 ± 17, 27 ± 17, 1.1 ± 0.56 mCi respectively (mean residual 4.9% ± 2.8%) across flex-dosing precalibrations including 1-day, 2-day, and 3-day SIROS (4/51, 16/51, and 28/51). Mean liver treatment volume was 483 ± 306 ml with target dose mean of 128 ± 26 Gy in non-segmentectomy cases; Radiation segmentectomy was performed in 15/48 (31%). Arterial stasis was documented in 9/48 (19%) of cases. Use of a 3-day precalibrated SIROS dose, use of activity <10 mCi, treatment of smaller liver volumes (<200 ml) and documentation of stasis were associated with higher residual activity ( P  = 0.025, P  = 0.0007, P  = 0.0177, and P  = 0.049, respectively) were associated with higher residuals. CONCLUSION: Combining the new technologies of SIROS and the Truselect microcatheter with a double-flush protocol yielded <10% residual in 94% of y90 infusions. Future studies may clarify if the predictors of high residual dose seen here may warrant microcatheter-specific considerations for dosimetry or dose preparation at the Radiopharmacy level.

Salvage Cryoablation for Local Recurrences of Thyroid Cancer Inseparable from the Trachea and Neurovascular Structures.

PURPOSE: To demonstrate safety, feasibility, and effectiveness of cryoablation of recurrent papillary thyroid cancer ineligible for reoperation because of scarring, eligible for focal ablation as defined within 2015 American Thyroid Association guideline sections C16 and C17. MATERIALS AND METHODS: With multidisciplinary consensus, cryoablation was performed with curative intent for 15 tumors in 10 patients between January 2019 and July 2021. Demographics, procedural details, and serial postprocedural imaging findings were analyzed. RESULTS: The mean age was 72.5 years (range, 57-88 years), and 80% of the patients were women. The tumors (mean size, 16 mm ± 6; range, 9-29 mm) received 1 session of cryoablation with 100% technical success. The mean and median postcryoablation tumor volumetric involution rates were 88% and 99%, respectively, with 9 (60%) of 15 tumors involuting completely or down to the scar and 6 (40%) involuting partially at the end of the study period. Tumor size did not increase after cryoablation (0% local progression rate). All tumors abutted the trachea, skin, and/or vascular structures, and hydrodissection failed in all cases because of scarring. The major adverse event rate was 20% (3/15), with 2 cases of voice change and 1 case of Horner syndrome; all resolved at 6 months with no permanent sequelae. No vascular, tracheal, dermal, or infectious adverse events occurred during a mean follow-up of 242 days (range, 114-627 days). One patient died at 386 days after cryoablation because of unrelated cholangiocarcinoma. CONCLUSIONS: Cryoablation of local recurrences of papillary thyroid cancer abutting the trachea and/or neurovascular structures in the setting of hydrodissection failure because of scarring yielded a mean volumetric involution of 88%, primary efficacy of 60%, and objective response rate of 100% with no local recurrences or permanent complications during a mean follow-up of 242 days. The secondary efficacy and longer-term outcomes remain forthcoming.

Percutaneous Image-guided Cryoneurolysis: Applications and Techniques.

The expansion and dissemination of interventional cryoneurolysis in recent years has been fueled by the integration of advanced imaging guidance, the evolution of our understanding of neuropathologic processes after exposure of nerves to cold, and opportunities for its use beyond pain management. The clinical translation of cryoneurolysis through interventional radiology requires consideration of many factors, including (a) the supply and composition of target nerves, (b) the value of diagnostic injection with imaging guidance for confirmation, (c) the integration of advanced imaging guidance that allows safe ablation, (d) the difference between neoplastic and nonneoplastic causes of pain, (e) the phenomenon of percutaneously induced neuroregeneration, (f) the potential to manage conditions other than pain, (g) the consideration of protocols, (h) the limitations of current technology, and (i) the potential complications and adverse effects. Cryoneurolysis has societal and legislative endorsement as an effective nonopioid option for pain palliation. The Centers for Medicare and Medicaid Services (CMS) approved three new category III Current Procedural Terminology (CPT) codes specifically for the cryoablation of nerves with advanced imaging guidance. Interventional radiologists who are aware of nerve-directed strategies see eligible patients in their daily practice and have opportunities to bundle procedures (eg, celiac plexus block at the time of a biliary drain for pancreatic cancer with low bile duct obstruction), offering an avenue to serve the patient, reduce opioid dependence, allow faster discharge, and establish name recognition of interventional radiologists. Also, the ability to use CT to target deep structures accurately and swiftly, often with only local anesthesia, compared with the usual monitored anesthesia care in a surgical setting, may provide another avenue to build a cryoneurolysis practice. ©RSNA, 2022.

Juxtametallic Bipolar Bone Radiofrequency Ablation: Thermal Monitoring in an Ex-Vivo Model with Specimen MRI and Histopathologic Correlation.

PURPOSE: To measure the ablation zone temperature and nontarget tissue temperature during radiofrequency (RF) ablation in bone containing metal instrumentation versus no metal instrumentation (control group). MATERIALS AND METHODS: Ex vivo experiments were performed on 15 swine vertebrae (control, n = 5; titanium screw, n = 5; stainless steel screw, n = 5). Screws and RF ablation probe were inserted identically under fluoroscopy. During RF ablation (3 W, 5 minutes), temperature was measured 10 mm from RF ablation centerpoint and in muscle contacting the screw. Magnetic resonance (MR) imaging, gross pathologic, and histopathologic analyses were performed on 1 specimen from each group. RESULTS: Ablation zone temperatures at 2.5 and 5 minutes increased by 12.2 °C ± 2.6 °C and 21.5 °C ± 2.1 °C (control); 11.0 °C ± 4.1 °C and 20.0 °C ± 2.9 °C (juxta-titanium screw), and 10.0 °C ± 3.4 °C and 17.2 °C ± 3.5 °C (juxta-stainless steel) screw; differences among groups did not reach significance by analysis of variance (P = .87). Mixed-effects linear regression revealed a statistically significant increase in temperature over time in all 3 groups (4.2 °C/min ± 0.4 °C/min, P < .001). Compared with the control, there was no significant difference in the temperature change over time for titanium (-0.3 °C/min ± 0.5 °C/min, P = .53) or steel groups (-0.4 °C/min ± 0.5 °C/min, P = .38). The mean screw temperature at the final time point did not show a statistically significant change compared with baseline in either the titanium group (-1.2 °C ± 2.3 °C, P = .50) or steel group (2.6 °C ± 2.9 °C, P = .11). MR imaging and pathologic analyses revealed homogeneous ablation without sparing of the peri-hardware zones. CONCLUSIONS: Adjacent metallic instrumentation did not affect the rate of or absolute increase in temperature in the ablation zone, did not create peri-metallic ablation inhomogeneities, and did not result in significant nontarget heating of muscle tissue in contact with the metal instrumentation.

Thermal Protection Strategies and Neuromonitoring during Ablation.

Advanced interventional pain management approaches seek to lesion neural targets to achieve desirable analgesia; however, equally important is preservation of motor and sensory function for regional bystander nerves. The topic of neuroprotection is also relevant for thermal ablation of metastatic bone tumors in the vicinity of neural structures. This report aims to provide an IR-directed framework of thermoprotective techniques available during thermal ablation.

CT-Guided Cooled Radiofrequency Denervation for Chronic Arthritis Pain of the Hip and Shoulder.

The paradigm in the treatment of arthritis pain is shifting for previously open surgical denervations of the hip and shoulder, as it already has for the geniculate nerves in knee arthritis. Interventional radiology is poised to contribute to this space with the use of CT guidance to provide safe, fast, and effective targeting of the target nerves for unequivocal diagnostic nerve block and definitive cooled radiofrequency denervation. The authors provide the background of which nerves are targeted for hip and shoulder denervation and the normal CT appearance of these blocks.

Interventional Radiology Regional Anesthesia Approaches for Intra- and Postprocedural Pain Control.

Effective pain control enables procedural success and improved patient satisfaction in interventional radiology. Regional anesthesia techniques are now established for intraoperative and postoperative anesthesia during major surgery, and interventional radiologists (IRs) can readily apply these injections for intraprocedural nerve blocks that can reduce anesthetic requirements and ensure durable analgesia postprocedure. Moreover, IR is poised to advance this field with novel blocks unique to IR needs and by blocking deep plexi safely reachable with CT guidance (e.g., hepatic hilar plexus, aorticorenal plexus blocks). This report aims to provide a succinct IR-directed primer for image-guided nerve blocks usable in the interventional radiology suite.

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.

Role of Thyroid RFA in the Treatment of Autonomously Functioning Thyroid Nodules.

Autonomously functioning thyroid nodules (AFTN) are a common cause of hyperthyroid symptoms. While hemithyroidectomy or radioactive iodine ablation have historically been used to treat AFTNs, percutaneous thyroid radiofrequency ablation (RFA) is emerging as a promising option for outpatient therapy. The technique is compared to medical therapy, radioactive iodine therapy, and surgery, with an emphasis on technical differences in the ablation procedure for AFTN vs other benign thyroid nodules.

Image guidance in osteoplasty and fixation.

Oncology patients, particularly those with breast, colorectal, prostate, renal and pancreatic cancers, are living longer due to advances in detection, and treatment. Unfortunately, this has come with a commensurate increase in the prevalence of osseous metastases and skeletal related events approaching 100,000 new patients each year. Patients are now experiencing serious morbidity and mortality due to pathologic fractures, altered structural mechanics, and cancer related bone pain. This patient population poses challenges for conventional open surgical and/or medical management often due to disease extent, location, and, in general, poor surgical candidacy. Percutaneous techniques may also be challenging under image guidance due to limited ability to use traditional orthopedic corridors, loss of cortical landmarks with destructive lesions, and need for live image guidance. Modern angiography suites with cone beam computed tomography (CBCT) and advanced imaging applications including needle guidance, 3D fusion, tumor segmentation, and angio-CT have facilitated the development of novel minimally invasive techniques for pain palliation and stabilization. The interventional radiologist is uniquely positioned to harness these advanced imaging applications and offer effective, safe, minimally invasive treatment options to patients with neoplastic disease within the axial, and appendicular skeletons. The focus of this article is to address the technical aspects of patient preparation, positioning, advanced imaging system capabilities, guidance strategies, and pitfalls during osteoplasty and fixation procedures.

Augmented reality overlay fluoroscopic guidance versus CT-fluoroscopic guidance for sacroplasty.

PURPOSE: To evaluate patient outcomes after sacroplasty (percutaneous sacral augmentation) with guidance using CT compared to fluoroscopy with augmented reality overlay using fluoroscopic cone-beam CT and FDA-approved software (CBCT-AF). MATERIALS AND METHODS: Retrospective IRB-approved study of all patients undergoing sacroplasty between 3/2019-9/2020 was performed. Procedural details were collected including whether the procedure was performed with CT-fluoroscopic guidance versus cone beam CT with vector navigation and real-time neuroforaminal contour overlay. Clinical details collected included Visual Analogue Scale (VAS) pain scores within 6-months post intervention. Images were analyzed on PACS to measure exact volumes of implanted cement. RESULTS: Twelve patients underwent sacroplasty using either CT (n = 13 hemisacra) or CBCT-AF (n = 10 hemisacra). No clinically significant complications occurred. Comparing CT versus CBCT-AF guidance there was no significant difference in radiation dose (CBCT-AF trended toward lower dose, p = 0.20), total anesthesia time (p = 0.71), or infused cement volume (p = 0.21). VAS pain scores decreased an average of 6.14 and 5.25 points for the CT and CBCT-AF groups respectively (p = 0.46, no significant difference between groups). CONCLUSION: Sacroplasty improved back pain in all patients, while CBCT-AF safely provided similar outcomes with trends toward lower radiation dose and cement volume compared to CT-fluoroscopy.

Future of kidney imaging: Functional magnetic resonance imaging and kidney disease progression.

INTRODUCTION: Chronic kidney disease (CKD) which is a common cause of death has an increasing trend, but there is no established approach for predicting CKD progression yet. Functional magnetic resonance imaging (fMRI) studies such as blood oxygenation level-dependent MRI (BOLD-MRI), diffusion-weighted MRI (DWI-MRI), diffusion-tensor MRI (DTI-MRI) and arterial spin labelling MRI (ASL-MRI) are rising methods for the assessment of kidney functions in native and transplanted kidneys as well as the estimation of CKD progression. METHODS: Systematic literature review was performed through the Embase (Elsevier), Cochrane Central Register of Controlled Trials (Wiley), PubMed/Medline and Web of Science databases, and studies investigating the role of fMRI methods assessing kidney functions in native and transplanted kidneys, as well as the value of fMRI methods to predict CKD progression, were included. Working mechanisms, advantages and limitations of the fMRI modalities were reviewed, and three studies investigating the role of fMRI studies in kidney functions were analysed. RESULTS AND CONCLUSION: BOLD-MRI signal was found to be inversely correlated with annual eGFR change, and DWI/ADC (apparent diffusion coefficient map) values were shown to be correlated with annual eGFR decline. fMRI methods which are currently used for other systems can be utilized to provide more detailed information about kidney functions, and doctors should be ready to interpret kidney MRIs.

Fatty kidney: A possible future for chronic kidney disease research.

BACKGROUND: Metabolic syndrome is a growing twenty-first century pandemic associated with multiple clinical comorbidities ranging from cardiovascular diseases, non-alcoholic fatty liver disease and polycystic ovary syndrome to kidney dysfunction. A novel area of research investigates the concept of fatty kidney in the pathogenesis of chronic kidney disease, especially in patients with diabetes mellitus or metabolic syndrome. AIM: To review the most updated literature on fatty kidney and provide future research, diagnostic and therapeutic perspectives on a disease increasingly affecting the contemporary world. MATERIALS AND METHOD: We performed an extensive literature search through three databases including Embase (Elsevier) and the Cochrane Central Register of Controlled Trials (Wiley) and PubMed/Medline Web of Science in November 2021 by using the following terms and their combinations: 'fatty kidney', 'ectopic fat', 'chronic kidney disease', 'cardiovascular event', 'cardio-metabolic risk', 'albuminuria' and 'metabolic syndrome'. Each study has been individually assessed by the authors. RESULTS: Oxidative stress and inflammation, Klotho deficiency, endoplasmic reticulum stress, mitochondrial dysfunction and disruption of cellular energy balance appear to be the main pathophysiological mechanisms leading to tissue damage following fat accumulation. Despite the lack of large-scale comprehensive studies in this novel field of research, current clinical trials demonstrate fatty kidney as an independent risk factor for the development of chronic kidney disease and cardiovascular events. CONCLUSION: The requirement for future studies investigating the pathophysiology, clinical outcomes and therapeutics of fatty kidney is clear.

Safety Profile of Particle Embolization for Treatment of Acute Lower Gastrointestinal Bleeding.

PURPOSE: To assess ischemic adverse events following particle embolization when used as a second-line embolic to coil embolization for the treatment of acute lower gastrointestinal bleeding (LGIB). MATERIALS AND METHODS: The single-institution retrospective study examined 154 procedures where embolization was attempted for LGIB. In 122 patients (64 men; mean age, 69.9 years), embolization was successfully performed using microcoils in 73 procedures, particles in 34 procedures, and both microcoils and particles in 27 procedures. Particles were used as second-line only when coil embolization was infeasible or inadequate. Technical success was defined as angiographic cessation of active extravasation after embolization. Clinical success was defined as the absence of recurrent bleeding within 30 days of embolization. RESULTS: Technical success for embolization of LGIB was achieved in 87% of the cases (134/154); clinical success rate was 76.1% (102/134) among the technically successful cases. Clinical success was 82.2% (60/73) for coils alone and 68.9% (42/61) for particles with or without coils. Severe adverse events involving embolization-induced bowel ischemia occurred in 3 of 56 (5.3%) patients who underwent particle embolization with or without coils versus zero of 66 patients when coils alone were used (P = .09). In patients who had colonoscopy or bowel resection within 2 weeks of embolization, ischemic findings attributable to the procedure were found in 3 of the 15 who underwent embolization with coils alone versus 8 of 18 who underwent embolization with particles with or without coils (P = .27). CONCLUSIONS: Particle embolization for the treatment of LGIB as second-line to coil embolization was associated with a 68.9% clinical success rate and a 5.3% rate of ischemia-related adverse events.