Lu, Aiming

Dynamic gadopiclenol-enhanced nodal and pedal MR lymphangiography was safe, with no adverse events, and feasible for imaging peripheral and central conducting lymphatic anatomy.

Abstract Objective . The use of Feraheme (ferumoxytol) as a contrast agent in MR-guided focused ultrasound (MRgFUS) tumor ablations could enhance treatment safety and efficacy by improving vascular visualization through strong T1 and T2 shortening effects. However, Feraheme impact on MR thermometry and tissue heating is unclear. This study evaluates the feasibility of incorporating Feraheme into MRgFUS by assessing its impact on MR imaging contrast, MR thermometry, and thermal response in tissue-mimicking phantoms. Approach . Tissue-mimicking phantoms with 0 (baseline), 0.25, and 0.5 mM Feraheme concentrations were prepared using a validated recipe. Acoustic attenuation was measured with a commercial diagnostic ultrasound scanner. MR imaging at 1.5 T was performed to assess gradient-recalled-echo (GRE)-based thermometry signal-to-noise-ratio (SNR), relaxation rates, and relaxivities. MRgFUS system integrated with 1.5 T MRI was used to perform multiple sonications in the phantoms. Temperature elevations and focal heating areas were quantified from proton resonance frequency (PRF) shift thermometry. Experiments were repeated three times over the period of eight-weeks. Separately, temperature-dependent nuclear magnetic resonance (NMR) spectroscopy was performed at 3.0 T in saline-diluted Feraheme phantoms (0, 0.25, 0.5, and 1.0 mM) to assess the influence of Feraheme concentration on PRF coefficients used in MR thermometry. Main results . Phantoms showed nuclear relaxation times ( T 1: 1178.1 ± 77.8, T 2: 103.21 ± 2.45 ms) and attenuation coefficients (0.34–0.36 dB cm −1 MHz −1 ) within expected biological tissue ranges. Relaxivities demonstrated a strong linear dependence on Feraheme concentration ( r 1: 17.5 ± 0.2, r 2: 209.2 ± 2.6 s −1 mM −1 ). Relative to baseline (0 mM) phantom, the SNR of GRE-based thermometry increased by 12.6% at 0.25 mM and decreased by 27.1% at 0.5 mM. Sonications in Feraheme-containing phantoms resulted in statistically higher temperature elevations ( p < 0.001 ) although no statistically significant difference was observed between 0.25 and 0.5 mM. All NMR measurements demonstrated stable, linear PRF temperature dependence ( R 2 = 0.996–0.999), with PRF coefficients (between −0.0074 and −0.0082 ppm °C −1 ). The resulting thermometry bias was small and predictable (+0.67 and +1.73 per 20 °C at 3.0 T for 0.25 and 0.5 mM). Significance . These findings demonstrate that MR thermometry remains feasible at moderate Feraheme concentrations and support its potential use to enhance visualization of critical vasculature near targeted tissues during MRgFUS.

Abstract Background We previously identified circulating and MRI biomarkers associated with the surgical management of Crohn’s disease (CD). Here we tested associations between these biomarkers and ileal resection inflammation and collagen content. Methods Fifty CD patients undergoing ileal resection were prospectively enrolled at 4 centers. Circulating CD64, extracellular matrix protein 1 (ECM1), GM-CSF autoantibodies (GM-CSF Ab), and fecal calprotectin were measured by ELISA. Ileal 3-dimensional magnetization transfer ratio (3D MTR), modified Look-Locker inversion recovery (MOLLI) T1 relaxation, diffusion-weighted intravoxel incoherent motion (IVIM), and the simplified magnetic resonance index of activity (sMaRIA) were measured by MRI. Ileal resection specimen acute inflammation was graded, and collagen content was measured quantitatively using second harmonic imaging microscopy. Associations between biomarkers and ileal collagen content were tested. Results Median (interquartile range [IQR]) age was 19.5 (16-33) years. We observed an inverse relationship between ileal acute inflammation and collagen content (r = −0.39 [95% confidence interval {CI}: −0.61, −0.10], P = .008). Most patients (33 [66%]) received biologics, with no variation in collagen content with treatment exposures. In the univariate analysis, CD64, GM-CSF Ab, fecal calprotectin, and sMaRIA were positively associated with acute inflammation and negatively associated with collagen content (P &lt; .1). The multivariable model for ileal collagen content (R2 = 0.31 [95% CI: 0.11, 0.52]) included log CD64 (β = −.27; P = .19), log ECM1 (β = .47; P = .06), log GM-CSF Ab (β = −.15; P = .01), IVIM f (β = .29, P = .10), and IVIM D* (β = 1.69, P = .13). Conclusions Clinically available and exploratory circulating and MRI biomarkers are associated with the degree of inflammation versus fibrosis in CD ileal resections. With further validation, these biomarkers may be used to guide medical and surgical decision-making for refractory CD.

Motor-evoked potential (MEP) monitoring is an electrophysiologic technique useful for testing peripheral motor nerve integrity during cryoablation cases with risk of nerve injury. Previously, neuromonitoring within the magnetic resonance imaging (MRI) suite for cryoablation has not been performed as magnetic needles are used which could cause magnetic field interactions with neuromonitoring leads. We present the first report of a patient who underwent MEP monitoring during MRI-guided cryoablation of a vascular malformation adjacent to the brachial plexus. We demonstrate that MEPs may be safely and accurately performed by interleaving MRI and MEPs during treatment, reducing the risk of postprocedural complications.

Abstract Osteoarthritis of the knee is a common cause of pain, functional disability, and reduced quality of life in the elderly. Despite its prevalence, there are limited currently available noninvasive treatment options. MRI-guided focused ultrasound (MRgFUS) is a noninvasive thermal ablation method which is used in a spectrum of musculoskeletal conditions. It is FDA approved for the treatment of painful bone metastases and osteoid osteoma, and has been considered for the treatment of other painful conditions such as osteoarthritis. The purpose of this case report is to describe the use of MRgFUS for the treatment of osteoarthritic knee pain in a 72-year-old male. The patient led an active lifestyle, however suffered significant limitations due to lateral knee pain with jogging and walking down the stairs. MRgFUS ablation treatment was performed to the lateral knee, targeting the periosteum in the patients’ area of pain. Following treatment, he experienced considerable reduction in his activity limiting symptoms with a duration of at least 6 months. Similar pain reduction was observed in two small series of MRgFUS treatment of knee pain from Japan. It is important for radiologists to be aware of MRgFUS as an innovative ablation modality. MRgFUS appears promising as a safe, non-invasive treatment option for temporary relief of knee pain. This may be particularly valuable for patients who are unwilling or unable to undergo total knee arthroplasty.

Abstract Background Despite advances in medical therapy, many children and adults with ileal Crohn’s disease (CD) progress to fibrostenosis requiring surgery. We aimed to identify MRI and circulating biomarkers associated with the need for surgical management. Methods This prospective, multicenter study included pediatric and adult CD cases undergoing ileal resection and CD controls receiving medical therapy. Noncontrast research MRI examinations measured bowel wall 3-dimensional magnetization transfer ratio normalized to skeletal muscle (normalized 3D MTR), modified Look-Locker inversion recovery (MOLLI) T1 relaxation, intravoxel incoherent motion (IVIM) diffusion-weighted imaging metrics, and the simplified magnetic resonance index of activity (sMaRIA). Circulating biomarkers were measured on the same day as the research MRI and included CD64, extracellular matrix protein 1 (ECM1), and granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies (Ab). Associations between MRI and circulating biomarkers and need for ileal resection were tested using univariate and multivariable LASSO regression. Results Our study sample included 50 patients with CD undergoing ileal resection and 83 patients with CD receiving medical therapy; mean participant age was 23.9 ± 13.1 years. Disease duration and treatment exposures did not vary between the groups. Univariate biomarker associations with ileal resection included log GM-CSF Ab (odds ratio [OR], 2.87; P = .0009), normalized 3D MTR (OR, 1.05; P = .002), log MOLLI T1 (OR, 0.01; P = .02), log IVIM perfusion fraction (f; OR, 0.38; P = .04), and IVIM apparent diffusion coefficient (ADC; OR, 0.3; P = .001). The multivariable model for surgery based upon corrected Akaike information criterion included age (OR, 1.03; P = .29), BMI (OR, 0.91; P = .09), log GM-CSF Ab (OR, 3.37; P = .01), normalized 3D MTR (OR, 1.07; P = .007), sMaRIA (OR, 1.14; P = .61), luminal narrowing (OR, 10.19; P = .003), log C-reactive protein (normalized; OR, 2.75; P = .10), and hematocrit (OR, 0.90; P = .13). Conclusion After accounting for clinical and MRI measures of severity, normalized 3D MTR and GM-CSF Ab are associated with the need for surgery in ileal CD.

The purpose of this study is to investigate the potential of using ultrasound gel to mitigate the risks of skin burn at the insertion site during microwave ablation (MWA) using non-actively cooled applicators. Ex vivo experiments in porcine tissue were conducted using two identical MWA systems. Five MWA scenarios were tested at different applicator insertion depths with an ultrasound gel layer applied at the applicator insertion sites: 8 cm insertion depth with and without 4 cm thick gel, 10 cm insertion depth with and without 2 cm thick gel, and 12 cm insertion depth without gel (reference). In all experiments, temperature elevations at the applicator insertion site on the tissue surface were recorded using thermal sensors in all experiments during 10-min MWA. The application of ultrasound gel and increasing applicator insertion depths resulted in measurable reductions in temperature elevations at the applicator insertion sites. For an insertion depth of 8 cm, the temperature elevations were 39.9 ± 4.7°C and 23.2±6.5°C without and with gel, respectively (P < 0.001). For an insertion depth of 10 cm, the temperature elevations were 20.8 ± 1.5°C and 14.4 ± 1.5°C without and with gel, respectively (P < 0.001). The maximal temperature elevations corresponding to an 8 cm insertion depth with gel were comparable with those corresponding to a 10 cm insertion depth without gel. Similarly, the maximal temperature elevations (12.2 ± 1.8°C) corresponding to 12 cm insertion depth without gel were comparable to those corresponding to 10 cm insertion depth with gel. Applying ultrasound gel at the applicator insertion site can significantly reduce temperature elevations at the tissue surface during MWA procedures.

Abstract Objective To evaluate the safety and tolerability of MRI-guided focused ultrasound (MRgFUS) for the treatment of facet joint–mediated pain in human subjects for whom conventional treatment had failed. Secondarily, to evaluate effectiveness of the procedure. Methods Consecutive patients who underwent MRgFUS at our institution were retrospectively identified. Chart review was performed to obtain relevant clinical and technical data. All patients had chronic low back pain and positive comparative medial branch blocks. Results Twenty-six MRgFUS treatments in 20 patients were included. Mean sonication energy was 1436.6 Joules. The procedure was technically successful in all patients. Of the treated patients, 29.6% experienced short-term worsening of low back pain immediately after the procedure, all by 1–4 points on a 0–10 scale. One patient (3.8%) reported temporary worsening of preexisting radicular symptoms after the procedure. Of 21 treatments with clinical follow-up of at least 3 months available, 12 (57.1%) had &gt;3 months’ pain relief, 2 (10%) had &lt;3 months’ benefit, 6 (30%) reported no benefit, and 1 (5%) patient was lost to follow-up. In patients who reported at least some benefit with prior conventional radiofrequency ablation, 8/10 (80%) benefited from the MRgFUS procedure. Conclusion The present study demonstrates that MRgFUS ablation of the lumbar facet joints is a safe and tolerable procedure in human subjects and could provide another option for patients for whom radiofrequency ablation had failed. More than half of all patients received significant durable pain relief, which jumped to 80% for patients who had experienced at least some benefit from prior radiofrequency ablations.

Background: Percutaneous image-guided thermal ablation has emerged as a treatment option for vascular malformations (VM). However, prospective data on intermediate to long-term effectiveness with uniform follow-up are lacking. Purpose: To prospectively evaluate the 12-month pain severity and pain interference outcomes following percutaneous MRI-guided laser ablation and cryoablation of focal painful, peripheral soft tissue VM. Materials and Methods: Participants undergoing clinically indicated MRI-guided laser ablation and cryoablation for focal painful (worst pain ≥4 out of 10 on Visual Analog Scale), peripheral soft tissue vascular malformations (VM) were enrolled in an IRB-approved prospective, observational study after giving informed consent. Participants completed the Brief Pain Inventory questionnaire prior to ablation and 1, 3, 6, and 12-month postablation. Differences in pain severity and interference outcomes from baseline on a 0 to 10 scale were compared using a paired t-test. Results: Seventeen participants (15 female; mean age 28.3 ± 9.3 years) underwent 24 MRI-guided and monitored ablation sessions including laser (n = 21), cryoablation (n = 2), or both (n = 1) for treatment of painful slow-flow (n = 16) or high-flow (n = 1) VM. Median maximal VM diameter was 5.7 cm (range 1.1 to 31.0 cm). Mean (±SD) preablation worst pain score was 7.9 ± 1.4. There was a significant decrease in worst pain at 1-month postablation (–3.5 ± 2.9; P = .0007) that was sustained at 3 (–3.4 ± 3.2; P = .0007), 6 (–4.2 ± 3.6; P = .0003), and 12 months (–3.6 ± 3.9; P = .002), with similar results for average, current, and least pain scores. There was a significant improvement in pain interference outcomes at 12-month postablation: general activity (P = .018), walking ability (P = .008), work (P = .003), sleep (P = .007), and enjoyment of life (P = .033). Conclusions: These data suggest that MRI-guided and monitored thermal ablation is safe and provides early and sustained significant improvements in pain severity and pain interference outcomes during the first year of follow-up in participants with focal painful peripheral soft tissue VM.