Post-procedural MRI Research Articles

Sonodynamic therapy with a single neoadjuvant, diffuse delivery of low-intensity ultrasound with 5-ALA in treatment naïve glioblastoma results in tumor-specific cytotoxic edema and increased apoptosis.

Sonodynamic therapy, which combines a tumor cell-selective sonosensitizer with ultrasound, is gaining attention as a promising new treatment approach for glioblastoma. The objective of this case study is to report on the first applications of 5-aminolevulinic acid (5-ALA) in combination with low-intensity, non-targeted ultrasound as neo-adjuvant treatment in therapy naïve glioblastoma. Three patients with therapy naïve newly diagnosed glioblastoma were treated once before cytoreductive surgery with 5-ALA in combination with hemispheric, low-intensity, non-targeted ultrasound, assuming cell death to be triggered by non-ablative activation of 5-ALA-induced, tumor selective porphyrins. No adverse effects were noted. Post-procedural MRI indicated a decrease in apparent diffusion coefficient values in tumors, suggesting cytotoxic effects. Relative cerebral blood volumes and leakage were increased for two patients with available perfusion imaging. Tissue obtained during surgery suggested increased cleaved-caspase III expression, a marker of apoptosis. We saw an immediate marked imaging response indicating cytotoxic edema and indications of a histopathology response from just a single treatment. Correlation to clinical outcomes and extension of overall survival remains to be seen. A Phase 1 safety study has been submitted for regulatory approval.

Incidence and predictors of asymptomatic cerebral infarction following radiofrequency catheter ablation for atrial fibrillation

Abstract Backgrounds Left atrial catheter ablation has been established as an important treatment option for atrial fibrillation (AF), but it carries the risk of periprocedural thromboembolism. Periprocedural major stroke is rare, but silent stroke does not appear to be rare. Accurate risk stratification for stroke and appropriate anticoagulation management are essential. Purpose We aimed to investigate the incidence and predictors of silent cerebral infarction (CI) associated with AF catheter ablation, detected by diffusion-weighted magnetic resonance imaging (DW-MRI). Methods and Results We performed a retrospective analysis of 618 consecutive patients (age 72±10 years, persistent atrial fibrillation (PEF) 45%, CHA2DS2-VASc score 2.6±1.4) with persistent or paroxysmal AF that underwent pulmonary vein (PV) or additional ablation and post-procedural cerebral MRI 1 day after ablation. During the ablation procedure, activated clotting time (ACT) was checked every 20 minutes, and additional heparin boluses were administered as needed to maintain ACT >320 seconds. Patients were analyzed for possible demographical, medical, echocardiographic, and procedural predictors of infarction events. Post-procedure DW-MRI detected new infarction lesions in 83 patients (13.4%:CI-group). There were no differences between the CI and non-CI groups with respect to age, type of anticoagulant and complex fractionated atrial electrogram ablation. Body weight, brain natriuretic peptide and left atrial diameter were significantly higher in the CI group. Left ventricular ejection fraction (LVEF) was significantly lower in the CI than non-CI group (58.6±12.6 vs. 64.2±11.8, P<0.001). PEF was more frequent in patients with CI than non-CI group (63.9 vs. 42.1%, P<0.001). In a multivariate regression model revealed only EF was a significant predictor for the occurrence of new asymptomatic lesions on post-procedural DW-MRI (OR 0.949, 95% CI 0.92-0.98, P=0.001). Conclusions This study shows a high incidence of silent micro-embolic events after AF ablation. Lower LVEF were potential predictors of this complication.

The Effect of Cooling Fluid Composition on Ablation Size in Hepatic Laser Ablation: A Comparative Study in an Ex Vivo Bovine Setting.

Hyperthermic ablation is a minimally invasive mode of tumour therapy which serves as a viable alternative to surgical intervention. However, one of the major drawbacks, besides the heat sink effect and the risk of damaging adjacent organs, is limited ablation size. The use of a cooling fluid during ablation has been shown to increase the ablation volume and decrease the carbonisation rate. The aim of this study was to investigate whether the composition of the cooling fluid has an effect on ablation size and carbonisation rate during hepatic laser ablation in an ex vivo bovine setting. In this study bovine hepatic tissue was ablated in an ex vivo setting using an internally cooled laser applicator. A total of 45 tissue samples were assigned to three groups: 0.9% saline infusion (n = 15), distilled water infusion (n = 15) and a 50%/50% mixture of 0.9% saline and distilled water (n = 15). Ablation was conducted using a 1064 nm Nd:YAG laser at a wattage of 25 W and time interval of 10 min. The ablation volume and carbonisation rate were then measured and recorded through postprocedural MRI. One-way ANOVA and post-hoc testing were performed to assess the effect of the cooling fluid composition on the ablation volumes. We found that using a mixture of saline and distilled water as a cooling fluid during hyperthermic ablation resulted in a larger ablation volume (mean ± SD: 22.64 ± 0.99 cm3) when compared to saline infusion (21.08 ± 1.11 cm3) or distilled water infusion (20.92 ± 0.92 cm3). This difference was highly significant (p < 0.001). There was no significant difference in ablation size between the saline group and the distilled water group. The highest carbonisation rate occurred in the saline group (12/15), followed by the mixed infusion group (3/15) and the distilled water group (1/15). The results of this study suggest that cooling fluid composition during hepatic laser ablation affects ablation volume in an ex vivo bovine setting. There was no statistically significant difference when comparing ablation volumes during saline infusion and distilled water infusion, but the carbonisation rate was significantly higher when using saline. The combination of saline and distilled water in a 50%/50% mixture as cooling fluid appears to be an auspicious alternative, as ablation volumes created with it are larger when compared to saline and distilled water alone, while carbonisation rate remains low. This might improve patient outcome as well as patient eligibility for hyperthermic ablation.

Percutaneous transluminal angioplasty and stenting of post-irradiated stenosis of subclavian artery: A matched case-control study

BackgroundAlthough radiotherapy is common for head/neck and chest cancers (HNCC), it can result in post-irradiation stenosis of the subclavian artery (PISSA). The efficacy of percutaneous transluminal angioplasty and stenting (PTAS) to treat severe PISSA is not well-clarified. AimsTo compare the technical safety and outcomes of PTAS between patients with severe PISSA (RT group) and radiation-naïve counterparts (non-RT group). MethodsDuring 2000 and 2021, we retrospectively enrolled patients with severe symptomatic stenosis (>60%) of the subclavian artery who underwent PTAS. The rate of new recent vertebrobasilar ischaemic lesions (NRVBIL), diagnosed on diffusion-weight imaging (DWI) within 24 h of postprocedural brain MRI; symptom relief; and long-term stent patency were compared between the two groups. ResultsTechnical success was achieved in all 61 patients in the two groups. Compared with the non-RT group (44 cases, 44 lesions), the RT group (17 cases, 18 lesions) had longer stenoses (22.1 vs 11.1 mm, P = 0.003), more ulcerative plaques (38.9% vs 9.1%, P = 0.010), and more medial- or distal-segment stenoses (44.4% vs 9.1%, P<0.001). The technical safety and outcome between the non-RT group and the RT group were NRVBIL on DWI of periprocedural brain MRI 30.0% vs 23.1%, P = 0.727; symptom recurrence rate (mean follow-up 67.1 ± 50.0 months) 2.3% vs 11.8%, P = 0.185; and significant in-stent restenosis rate (>50%) 2.3% vs 11.1%, P = 0.200. ConclusionThe technical safety and outcome of PTAS for PISSA were not inferior to those of radiation-naïve counterparts. PTAS for PISSA is an effective treatment for medically refractory ischaemic symptoms of HNCC patients with PISSA.

A Propensity-Matched Comparison of Ischemic Brain Lesions on Postprocedural MRI in Endovascular versus Open Carotid Artery Reconstruction.

(1) Study purpose: The aim of our prospective single-center, matched case-control study was to compare the number and volume of acute ischemic brain lesions following carotid endarterectomy (CEA) versus carotid artery stenting (CAS) using a propensity-matched design. (2) Methods: Carotid bifurcation plaques were analyzed by using VascuCAP software on CT angiography (CTA) images. The number and volume of acute and chronic ischemic brain lesions were assessed on MRI scans taken 12-48 h after the procedures. Propensity score-based matching was performed at a 1:1 ratio to compare the ischemic lesions on postinterventional MR. (3) Results: A total of 107 patients (CAS, N = 33; CEA, N = 74) were included in the study. There were significant differences in smoking (p = 0.003), total calcification plaque volume (p = 0.004), and lengths of the lesion (p = 0.045) between the CAS and CEA groups. Propensity score matching resulted in 21 matched pairs of patients. Acute ischemic brain lesions were detected in ten patients (47.6%) of the matched CAS group and in three patients (14.2%) in the matched CEA group (p = 0.02). The volume of acute ischemic brain lesions was significantly larger (p = 0.04) in the CAS group than in the CEA group. New ischemic brain lesions were not associated with neurological symptoms in either group. (4) Conclusions: Procedure-related new acute ischemic brain lesions occurred significantly more frequently in the propensity-matched CAS group.

MRI of Benign Prostatic Hyperplasia: Important Pre- and Posttherapeutic Considerations

New minimally invasive techniques that reduce morbidity while improving lower urinary tract symptoms (LUTS) due to benign prostatic hypertrophy (BPH) have become attractive alternatives for patients, in comparison to traditional techniques such as transurethral resection of the prostate (TURP) and simple prostatectomy. Pre- and postprocedural MRI is not routinely performed for LUTS due to BPH treatments. However, because of the combination of rapidly evolving treatments available for LUTS due to BPH and increasing demand for prebiopsy prostate MRI for detection of clinically significant prostate cancer (PCa), an understanding of procedural techniques and expected changes are important for accurate interpretation of prostate MRI performed after treatment of BPH. The authors discuss the imaging evaluation of LUTS due to BPH and emerging predictors of treatment success. The posttreatment appearance and underlying anatomic changes in the prostate after medical, surgical, and minimally invasive treatments including TURP, simple prostatectomy, laser enucleations and ablations, prostatic urethral lift, water vapor thermal therapy, and prostate artery embolization are detailed. Most procedures reduce prostate volume, notably in the periurethral prostatic tissue. Ablations create areas of necrosis and can distort the normal zonal anatomy between the transition zone and the peripheral zone, and prostate artery embolization creates infarcts in the transition zone. Mechanical prostatic urethral lift devices open the anterior channel at the bladder base but create susceptibility artifacts that can obscure and prevent detection of a lesion in the transition zone. Also discussed are the detection of clinically significant prostate cancer in the postprocedural prostate and imaging of BPH procedure complications such as urethral strictures, abscesses, and hematuria. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material. See the invited commentary by Purysko in this issue.

Flat-panel detector CT to assess intracranial hemorrhage immediately following mechanical thrombectomy.

The risk of symptomatic intracranial hemorrhage (ICH) approaches 5% despite mechanical thrombectomy (MT) efficacy for ischemic stroke secondary to large vessel occlusion. Flat-panel detector CT (FDCT) imaging with Syngo Dyna CT imaging (Siemens Medical Solutions, Malvern, PA) can be used immediately following MT to detect ICH. To evaluate the accuracy and reliability of FDCT imaging with Dyna CT compared to conventional post-MT CT and MRI. Head FDCT (20second, 70kV) was performed immediately following MT on 26 consecutive patients; postprocedural CT or MRI was obtained ∼24hours later. Two blinded, independent neuroradiologists evaluated all imaging, identifying ICH, stroke, and presence of subarachnoid contrast. Cohen's κ statistic was used to assess interrater agreement for each imaging outcome and compared the FDCT to conventional imaging. FDCT for ICH demonstrated a strong degree of interrater reliability (κ=0.896; 95% confidence interval [CI], 0.734-1.057). Negligible reliability was seen for ischemia determination on immediate post-MT FDCT (κ=0.149; 95% CI, -0.243 to 0.541). ICH evaluation between FDCT and post-MT conventional CT revealed modest interrater reliability (κ=0.432; 95% CI, -0.100 to 0.965), which did not reach statistical significance. There was no substantive reliability in the evaluation of ICH between FDCT and post-MT MRI (κ=0.118, 95% CI, -0.345 to 0.580). FDCT, such as Dyna CT, immediately post-MT is a promising tool that can expedite the detection of ICH with a high degree of reliability, although the detection of ischemic parenchymal changes is limited.

Prevention of in-stent restenosis with drug-eluting balloons in patients with postirradiated carotid stenosis accepting percutaneous angioplasty and stenting

ObjectiveTo investigate the technical safety and outcome of in-stent restenosis (ISR) prevention with drug-eluting balloon (DEB) in patients with postirradiated carotid stenosis (PIRCS) undergoing percutaneous angioplasty and stenting (PTAS).MethodsBetween 2017...

Effect of air removal with extracorporeal balloon inflation on incidence of asymptomatic cerebral embolism during cryoballoon ablation of atrial fibrillation: A prospective randomized study.

BackgroundIt was previously reported, based on a retrospective study, that preliminary removal of air bubbles in heparinized saline water with extracorporeal balloon inflation reduced the incidence of asymptomatic cerebral embolism (ACE). The present study aims to compare the incidence of ACE between a conventional and pre-inflation method during cryoballoon ablation in a prospective randomized controlled study.MethodsA total of 98 atrial fibrillation patients were enrolled and randomized into conventional and pre-inflation groups. Patients in the pre-inflation group received balloon massaging with preliminary extracorporeal balloon inflation in saline water before the cryoballoon was inserted into the body.ResultsThe baseline characteristics were similar between the two groups. Post-procedural 3-Tesla MRI revealed CE in 27.6% of patients. Symptomatic CE only occurred in two patients in the pre-inflation group. One patient had transient dysarthria and mild muscle weakness in one hand; the other patient complained of transient left upper limb weakness, left lower limb paresthesia and dysarthria. The incidence of ACE detected by cerebral MRI did not differ between the two groups to a statistically significant extent (conventional vs. pre-inflation; 22.9% vs. 29.2%; P = 0.49). In the multivariable analysis, eGFR was independently associated with the presence of ACE (odds ratio 0.95; 95% confidence interval 0.907–0.995; P = 0.03).ConclusionIn this prospective randomized study, the preliminary removal of air bubbles in heparinized saline water with extracorporeal balloon inflation had no impact on the incidence of ACE.

Assessing ablation margins of FDG-avid liver tumors during PET/CT-guided thermal ablation procedures: a retrospective study

To retrospectively assess liver tumor ablation margins using intraprocedural PET/CT images from FDG PET/CT-guided microwave or cryoablation procedures and to correlate minimum margin measurements with local progression outcomes. Fifty-six patients (ages 36 to 85, median 62; 32 females) with 77 FDG-avid liver tumors underwent 60 FDG PET/CT guided, percutaneous microwave, or cryoablation procedures. Single breath-hold PET/CT images were used for intraprocedural assessment of the tumor ablation margin: liver tumors remained visible on PET immediately following ablation; microwave ablation zones were visible using contrast-enhanced CT; cryoablation zones (ice balls) were visible using unenhanced CT. Two readers retrospectively determined ablation margin assessability and measured the minimum ablation margin on intraprocedural PET/CT (n = 77) and postprocedural MRI (n = 56). Local tumor progression was assessed on all available follow-up imaging (1-49 months, mean 15). Local tumor progression was correlated with PET/CT minimum margin measurements using clustered survival models for 61 tumors. Minimum ablation margins were more often assessable using intraprocedural PET/CT (≥ 73/77 tumors, 95%) than postprocedural MRI (≤ 35/56 tumors, 63%). In 61 tumors with PET/CT-assessable margins (excluding tumors with overlapping ablations after PET/CT), there was a 6-fold increased risk of local tumor progression [hazard ratio (HR) 6.05; P = 0.004] for minimum ablation margins < 5 mm. Breath-hold PET/CT scans, during PET/CT-guided microwave or cryoablation procedures for FDG-avid liver tumors, enable reliable intraprocedural assessment of the entire tumor ablation margin; a minimum PET/CT ablation margin threshold of 5 mm correlates well with local tumor progression outcomes.

MRI of the Internal Auditory Canal, Labyrinth, and Middle Ear: How We Do It.

MRI is firmly established as an essential modality in the imaging of the temporal bone and lateral skull base. It is used to evaluate normal anatomic structures, evaluate for vestibular schwannomas, assess for inflammatory and/or infectious processes, and detect residual and/or recurrent cholesteatoma. It is also extensively used in pre- and postoperative evaluations, particularly in patients with vestibular schwannomas and candidates for cochlear implantation. Nevertheless, despite the widespread use of MRI for these purposes, many radiologists remain unfamiliar with the complex anatomy and expected imaging findings with such examinations. The purpose of this review is to provide an overview of the most useful MRI sequences for internal auditory canal and labyrinthine imaging, review the relevant anatomy, and discuss the expected appearances of the most commonly encountered pathologic entities. In addition, the features at pre- and postprocedural MRI will be discussed to help ensure that diagnostic radiologists may be of greatest use to the ordering physicians. © RSNA, 2020.

Initial experience with the novel p64MW HPC flow diverter from a cohort study in unruptured anterior circulation aneurysms under dual antiplatelet medication.

Objectivep64MW HPC is a new low-profile flow diverter with reduced thrombogenicity due to hydrophilic coating. The purpose of this study was to evaluate its safety and efficacy in Mongolian patients under dual antiplatelet therapy.MethodsConsecutive patients with unruptured anterior circulation aneurysms were prospectively enrolled. All patients received aspirin and clopidogrel before and six months after the procedure, followed by lifelong aspirin medication. High platelet reactivity (VerifyNow) did not trigger further action. The safety and efficacy endpoints were clinical outcome and aneurysm occlusion.ResultsIn 29 patients (26 female, median age 57 years), 46 aneurysms (neck width 3.3 mm, fundus diameter 3.7 mm, median) were treated. Dual platelet function inhibition was confirmed in eight patients (28%). The response to Clopidogrel was between 100 and 239 P2Y12 reaction units (VerifyNow) in 13 patients (45%). Non-response to at least one drug was found in 8 of 29 patients (28%). One collapsed p64MW HPC required balloon angioplasty. No other periprocedural thrombus formation occurred. Postprocedural MRI revealed lesions with diffusion restriction in 3 of 29 patients. Digital subtraction angiography after three months for 42 of 46 (91%) aneurysms showed an adequate aneurysm occlusion in 25 (60%). Distal p64MW HPC migration of 3 implants was retreated with another p64MW HPC. Follow-up digital subtraction angiography of 26 of 46 (57%) aneurysms after six months showed adequate aneurysm occlusion in 22 (85%). Significant in-stent stenosis or thrombosis, morbidity or mortality was not encountered.Conclusionp64MW HPC implantation in patients under dual antiplatelet therapy with or without dual platelet function inhibition has a low procedural complication rate. The early aneurysm occlusion rate is high.

Abstract WP44: Less Infarct Volume Growth in Early Window Mechanical Thrombectomy Compared to Late Window in Emergent Large Vessel Occlusion

Background: While clearly beneficial based on outcome analysis, there has been limited data regarding prevention of further infarct growth in late (6-24 hour) compared to the early window (&lt;6 hour) mechanical thrombectomy (MT). More expedient revascularization in the early group prevents further growth, but the presence of good collaterals in late window patients may prevent infarct progression over time. The aim of this study is to compare infarct growth between early and late window intervention. Methods: We reviewed consecutive patients presenting to a comprehensive stroke center from January 2016 to December 2018 with emergent large vessel occlusion (ELVO) undergoing MT. Standard protocol included pre-procedural MRI imaging and only those with post-procedural MRI were included. Patients were divided into early (&lt;6 hour from onset to arterial puncture) and late (6-24 hour from onset to arterial puncture) groups. Infarct volume on MRI was measured using region of interest analysis by investigators blinded to group. MRI growth between pre- and post- MT MRI was compared using both absolute difference (post minus pre volume) and ratio (pre:post volume). Results: Among 117 patients meeting inclusion criteria, 40 (34.2%) patients had early and 77 (65.8%) late interventions. Those in the early group showed a trend toward lower infarct volume growth compared to those in the late group (16.0 +/- 42.9 vs 31.4 +/- 60.9 mL growth, p = 0.16). Ratios of pre to post MT infarct volume was significantly different in early and late intervention group (1.07 +/- 1.6 vs 0.63 +/- 0.33, p = 0.02), signifying less infarct growth in the early group. Conclusion: In patients with ELVO for whom MT was performed, there was less infarct growth in the early time window compared to the late window.

Abstract WMP9: Procedural Parameters Predicting Reduced MRI Infarct Growth in Mechanical Thrombectomy

Background: Successful recanalization after a single pass and shorter procedural duration during mechanical thrombectomy (MT) in emergent large vessel occlusion (ELVO) have been associated with both rapid neurologic improvement and long-term clinical outcome, although conflicting data exists regarding their direct effect on infarct growth. We aimed to determine whether less device passes or shorter procedural times are associated with decreased infarct growth. Methods: We reviewed consecutive patients presenting to a comprehensive stroke center from January 2016 to December 2018 with (ELVO). Standard protocol included pre-procedural MRI imaging and only those with post-procedural MRI were included in this study. Number of passes attempted and procedural times were recorded. Infarct volume on MRI was measured using region of interest analysis blinded to procedural outcomes. MRI infarct growth was analyzed using linear regression as a function of procedural times and number of passes. Results: Of 173 patients undergoing MT after MRI, 118 patients had MRI imaging post-procedure. Successful recanalization (TICI &gt;2b) was achieved in 106/118 patients. For each additional minute of procedural duration, MRI infarct growth increased by 0.23 mL (p=.04). Average MRI infarct growth was different amongst the passes (p=0.001): 14.65 mL in cases with only one pass (n=67), 25.67 mL with two passes (n=26), 28.68 mL with three passes (n=17), and 98.42 mL with four or greater passes (n=8). Conclusion: Longer procedural duration and increased number of passes are associated with increased MRI infarct growth.

Predicting the Fibroid-Migratory Impact of UAE: Role of Pre-embolization MRI Characteristics

AimTo investigate potential factors on MR imaging that could be used to predict migration of uterine fibroids post-UAE.Methods and MaterialsWe retrospectively reviewed patients referred for UAE having pre-procedural and 6 months post-procedural MRI, at a tertiary centre, over a 1-year period. Pre- and post-UAE images were reviewed in 64 women by two radiologists to identify the sub-type, dimensions, and infarction rate of each dominant fibroid. The shortest distance between the fibroid and the endometrial wall was measured to determine intramural fibroid movement. Paired sample T tests and two-sample T tests were used to compare between pre- and post-embolization variations and between migrated and non-migrated intramural fibroids, respectively. After preliminary results suggested potential predictors of intramural fibroids migration, we tested our findings against the non-dominant intramural fibroids in the same patients.ResultsReview of images revealed 35 dominant intramural fibroids, of which eight migrated to become submucosal fibroids, while five were either partially or completely expelled. These 13 migrated fibroids had a shorter pre-procedural minimum endometrial distance (range 1–2.4 mm) and greater maximum fibroid diameter (range 5.1–18.1 cm), when compared to non-migrating fibroids. On image reassessment, the migrated non-dominant intramural fibroids had a minimum endometrial distance and maximum fibroid diameter within the same range.ConclusionIntramural fibroids with a minimum endometrial distance less than 2.4 mm and a maximum fibroid diameter greater than 5.1 cm have a high likelihood of migrating towards the endometrial cavity after UAE.

P1033Impact of workflow modifications in atrial fibrillation ablation for reducing the incidence of silent cerebral lesions with a new multi-electrode radiofrequency balloon catheter

Abstract Background Silent cerebral lesions (SCL) often occur after invasive cardiac procedures. Reported SCL incidence with AF ablation varies (incidence, up to 50%), depending on technology used, procedural workflow, and detection method. Objective To evaluate the impact of ablation workflow modifications on SCL incidence following pulmonary vein isolation radiofrequency (RF) ablation with a novel multi-electrode RF balloon catheter in patients with symptomatic paroxysmal AF (PAF). Methods In the RADIANCE feasibility study of the balloon catheter, all enrolled patients who underwent ablation were screened for SCL using pre- and post-procedural diffusion-weighted MRI. Several modifications were made to the ablation workflow in a subsequent European registration study (SHINE) of the same catheter: eliminating dual transseptal access, using an over-the-wire mini lasso, continuously irrigating all side ports, bolus dosing with heparin before transseptal puncture, maintaining activated clotting time (ACT) at 350–400 sec, and setting a maximum temperature limit of 55°C (previously, 60–65°C). Interim data are presented for SHINE (data cutoff, 22 Oct 2018). Results In the neurological assessment evaluable (NAE) populations of RADIANCE (n=38) and SHINE (n=30), respectively, mean ages were 60.8±10.04 and 59.7±7.83 years, and 57.9% and 70.0% were male. One patient in each study had a history of TIAs. SCL incidences were 23.7% (10 lesions in 9 patients) in RADIANCE and 7.1% (2 lesions in 2 patients) in SHINE (excluding 1 SCL that occurred in a patient who failed to meet inclusion criteria [age&gt;75] and 1 SCL that occurred after data cut-off). SHINE NAE enrollment has since completed with no further SCL occurrences. Overall, mean ACTs were 344.3±24.55 sec in RADIANCE and 381.6±73.31 sec in SHINE (p=0.01); in patients with SCL, mean ACTs were 349.3±25.65 and 417.8±87.33 sec, respectively. Conclusion(s) Modifications to the workflow led to a decrease in the SCL incidence for PAF ablation using the novel RF balloon catheter. Acknowledgement/Funding These studies were sponsored by Biosense Webster, Inc.

03:36 PM Abstract No. 135 Utility of routine pelvic MRI in the clinical management of patients following uterine fibroid embolization

To assess the utility of routine pelvic MRI in the clinical management of patients following uterine fibroid embolization (UFE). Using PACS and electronic medical records, consecutive patients undergoing UFE for symptomatic fibroids from 2015 to 2017 and followed in interventional radiology (IR) clinic at 3 months post-UFE were identified. Routine 3-month post-UFE MRI was obtained in a subset of the cohort based on individual IR preference. MRI findings, clinical course, and clinical management changes (defined as gynecology referral for further intervention) were compiled. The proportion of patients with clinical management change in the MRI and non-MRI groups and compliance for follow-up in the two groups were compared using chi-square test. Of 175 patients undergoing UFE, 14 were lost to follow-up and excluded. Of 161 included patients, 60 underwent routine MRI, and 101 did not. In the MRI group, 7 patients had new or persistent symptoms. Follow-up MRI findings resulted in gynecological referral in 4 patients, of whom 3 (5%) required intervention. In the non-MRI group, 16 patients with new or persistent symptoms prompted 14 gynecology referrals and 3 (2.9%) further interventions. No difference existed in the proportion of patients in the two groups requiring further intervention (5% vs. 2.9% (p=0.528)). However, of the symptomatic patients referred, a significantly smaller proportion actually required intervention in the non-MRI group (n=3, 21.4%) vs. the MRI group (n=3, 75%; p=0.045). Routine MRI in asymptomatic patients never prompted management change (n=0). However, loss to follow-up was significantly reduced in patients scheduled for routine post-UFE MRI on the same day as their follow-up visit (n=1, 1.6%) vs. those scheduled for routine follow-up alone (n=13, 11.3%) (p=0.024). In patients with persistent or new symptoms following UFE, post-procedural MRI reduces unnecessary gynecological referrals by identifying patients who do not require further intervention. Although the routine use of post-UFE MRI in asymptomatic patients does not significantly change management, it is associated with significantly increased patient compliance with clinical follow-up.

The methodology for endoluminal irreversible electroporation in porcine models

The aim of this study was to describe the methodology of the surgical technique for endoluminal irreversible electroporation in the biliary tract performed within the perihilar region in porcine models. Endoluminal irreversible electroporation of the common bile duct was performed on eight porcine models using an endoluminal device inserted during laparotomy. The endoluminal device consisted of three electrodes 1 cm in length, attached at 120 degrees around the balloon catheter. The procedure was conducted with the following parameters: number of pulses 90, voltage of 1500 V between each couple of electrodes. Cross sectional imaging and histopathological assessment were employed for evaluations of the ablation zone. Models were sacrificed 24 h and 96 h after ablation. The treatment was successful in all porcine models. All animals survived the defined study period. Peri-ablation oedema within the hepatoduodenal ligament and adjacent liver tissue could be measured on post-procedural MRI or CT. Perforation in the site of ablation developed in one model. Histopathological examination showed heavy regressive changes of the ablated tissue. The elastic membranes of the adjacent portal vein were preserved in all models. In our experience, this novel endoluminal modality used within the perihilar region in porcine models is a feasible and well predictable procedure. Further studies should explore the optimal protocol of catheter-based ablation to limit complications.

Remote ischemic conditioning for stroke: clinical data, challenges, and future directions.

Despite great improvement during the past several decades, the management of stroke is still far from satisfactory, which warrants alternative or adjunctive strategies. Remote ischemic conditioning (RIC), an easy‐to‐use and noninvasive therapy, can be performed in various clinical scenarios (e.g., prehospital transportation, intrahospital, and at home), and it has been widely investigated for stroke management. RIC has been demonstrated to be well tolerated in patients with acute ischemic stroke and aneurysm subarachnoid hemorrhage, and it may benefit these patients by improving clinical outcomes; in patients with intracranial atherosclerosis, long‐term repeated RIC could be safely performed and benefit patients by reducing recurrent ischemic stroke and transient ischemic attack, as well as improving cerebral perfusion status; long‐term repeated RIC may also benefit patients with cerebral small vessel disease by slowing cognitive decline and reducing volume of white matter hyperintensities on brain MRI; in patients with severe carotid atherosclerotic stenosis undergoing stenting, preprocedural RIC could reduce the odds of new brain lesions on postprocedural MRI. Previous clinical studies suggest broad future prospects of RIC in the field of cerebrovascular diseases. However, the optimal RIC protocol and the mechanisms that RIC protects the brain is not fully clear, and there is lack of sensitive and specific biomarkers of RIC, all these dilemmas prevent RIC from entering clinical practice. This review focuses on recent advances in clinical studies of RIC in stroke management, its challenges, and the potential directions of future studies.

Volume of embolic agents in uterine artery embolization for leiomyoma: relation to baseline MRI

Purpose: To assess whether pre-procedural MRI findings predict the volume of tris-acryl gelatin microspheres (TAGM) used in uterine artery embolization (UAE) for leiomyomas.Material and methods: This was a retrospective, single-institution study. Between June 2014 and December 2017, 73 patients with leiomyomas underwent UAE with TAGM alone. Univariate and multivariate analyses were performed to assess the relationships between the volume of TAGM and baseline parameters. Technical outcomes, tumor infarction on post-procedural contrast-enhanced MRI, and complications were evaluated.Results: Technical success was achieved in all patients. Infarction of ≥90% of the total leiomyoma volume was observed in 93% (67/72) of patients. No major complications were noted. The mean (SD) volume of 500- to 700-μm particles used in all (73/73) patients was 10.3 ± 4.6 ml. The multivariate analysis revealed that uterine volume (p = .034) correlated with the 500- to 700-μm TAGM volume. Seven hundred- to 900-μm particles were added for 70% (51/73) of patients at a mean (SD) volume of 3.6 ± 4.6 ml. The dominant tumor volume (p = .028) correlated with the 700- to 900-μm TAGM volume.Conclusion: The dominant tumor or uterine volume on pre-procedural MRI was directly associated with the volume of TAGM required for embolization of leiomyomas.