Tiegs‐Heiden, Christin A.

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.

ABSTRACTRationalePatient reported outcome (PRO) measures are a critical tool to understand the patient's experience of their illness. Our institution collects PRO measures for patients receiving spine care through several modalities, including direct patient outreaches.Aims and ObjectivesWe designed a quality project to increase the total number of patient outreaches within 1 year, without increasing program resources or costs, by utilizing a return‐to‐work program.MethodSpine PRO collection rate data was extracted from the electronic health record by a data science analyst. This data included how many direct patient outreaches were completed each month and the average number of patient outreaches being completed by the patient outreach representative. For the balancing measure, full‐time equivalent costs were monitored throughout the baseline and pilot periods.ResultsDuring the 6‐month baseline period, 3477 patient outreaches were made, representing 14.5% of possible outreaches. During the first 3‐month post‐intervention remeasure period, 6272 patient outreaches were made, an increase of 55.44%. During the second 3‐month post‐intervention period, 9099 outreaches were made, an increase of 38.21% from the first remeasure. There was no increase in cost to the program related to the project.ConclusionThis increase in patient outreaches by return‐to‐work employees will translate to improvement in overall PRO collection rates, which may ultimately improve individual and population health care delivery.

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.

Epidural steroid injections are commonly performed using fluoroscopic or CT guidance. With both modalities, the injection of contrast material is necessary before steroid administration to ensure adequate epidural flow and exclude non-epidural flow. While fluoroscopic guidance is conventional, CT is utilized at some centers and can be particularly helpful in the setting of challenging or postoperative anatomy. It is important for proceduralists to be adept at evaluating contrast media flow patterns under both modalities. The goal of this review article is to describe and provide examples of epidural and non-epidural flow patterns on both conventional fluoroscopy and CT. Specific non-epidural patterns discussed include intrathecal flow, intradural/subdural flow, vascular uptake, flow into the retrodural space of Okada, inadvertent facet joint flow, and intradiscal flow.

Purpose To develop a machine learning model capable of identifying subscapularis tears before surgery based on imaging and physical examination findings. Methods Between 2010 and 2020, 202 consecutive shoulders underwent arthroscopic rotator cuff repair by a single surgeon. Patient demographics, physical examination findings (including range of motion, weakness with internal rotation, lift/push‐off test, belly press test, and bear hug test), and imaging (including direct and indirect signs of tearing, biceps status, fatty atrophy, cystic changes, and other similar findings) were included for model creation. Results Sixty percent of the shoulders had partial or full thickness tears of the subscapularis verified during surgery (83% of these were upper third). Using only preoperative imaging‐related parameters, the XGBoost model demonstrated excellent performance at predicting subscapularis tears (c‐statistic, 0.84; accuracy, 0.85; F1 score, 0.87). The top 5 features included direct signs related to the presence of tearing as evidenced on magnetic resonance imaging (MRI) (changes in tendon morphology and signal), as well as the quality of the MRI and biceps pathology. Conclusions In this study, machine learning was successful in predicting subscapularis tears by MRI alone in 85% of patients, and this accuracy did not decrease by isolating the model to the top features. The top five features included direct signs related to the presence of tearing as evidenced on MRI (changes in tendon morphology and signal), as well as the quality of the MRI and biceps pathology. Last, in advanced modeling, the addition of physical examination or patient characteristics did not make a significant difference in the predictive ability of this model. Level of Evidence Level III, diagnostic case‐control study.

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: Magnetic resonance imaging (MRI) is considered to be the gold standard for imaging of osteochondritis dissecans (OCD). Purpose/Hypothesis: The purpose was to determine the additional value of a preoperative computed tomography (CT) scan in adolescent patients with capitellar OCD of the elbow. Consistent with the fact that OCD is a lesion involving the subchondral bone, the hypothesis was that CT would be superior to MRI for imaging OCD of the capitellum. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: All patients being treated surgically for an OCD of the capitellum between 2006 and 2016 at one institution were reviewed for preoperative imaging. A total of 28 patients met the inclusion criteria. Corresponding MRI and CT scans were compared retrospectively. Multiple parameters were recorded, with special emphasis on OCD lesion size, fragmentation, and tilt as well as joint surface integrity, loose bodies, and osteophytes. Results: The OCD lesions were best seen on CT scans, whereas MRI T1-weighted images overestimated and T2-weighted images underestimated the size of defects. A subchondral fracture nonunion was found on CT scans in 18 patients, whereas this was seen on MRI T1-weighted images in only 2 patients ( P < .001) and MRI T2-weighted images in 4 patients ( P < .001). Fragmentation of the OCD fragment was found on CT scans in 17 patients but on MRI scans in only 9 patients ( P = .05). Osteophytes as a sign of secondary degenerative changes were seen on CT scans in 24 patients and were seen on MRI scans in 15 patients ( P = .02). Altogether, only 51 of 89 secondary changes including loose bodies, effects on the radial head and ulnohumeral joint, and osteophytes that were seen on CT scans were also seen on MRI scans ( P = .002). Conclusion: OCD fragmentation and secondary changes were more often diagnosed on CT. These factors indicate OCD instability or advanced OCD stages, which are indications for surgery. In an adolescent who is considered at risk for OCD (baseball, gymnastics, weightlifting, tennis) and who has lateral elbow joint pain with axial or valgus load bearing, CT is our imaging modality of choice for diagnosing and staging OCD of the capitellum.

AbstractBackgroundDual‐energy CT with virtual noncalcium (VNCa) images allows the evaluation of focal intramedullary bone marrow involvement in patients with multiple myeloma. However, current commercial VNCa techniques suffer from excessive image noise and artifacts due to material decomposition used in synthesizing VNCa images.ObjectivesIn this work, we aim to improve VNCa image quality for the assessment of focal multiple myeloma, using an Artificial intelligence based Generalizable Algorithm for mulTi‐Energy CT (AGATE) method.Materials and methodsAGATE method used a custom dual‐task convolutional neural network (CNN) that concurrently carries out material classification and quantification. The material classification task provided an auxiliary regularization to the material quantification task. CNN parameters were optimized using custom loss functions that involved cross‐entropy, physics‐informed constraints, structural redundancy in spectral and material images, and texture information in spectral images. For training data, CT phantoms (diameters 30 to 45 cm) with tissue‐mimicking inserts were scanned on a third generation dual‐source CT system. Scans were performed at routine dose and half of the routine dose. Small image patches (i.e., 40 × 40 pixels) of tissue‐mimicking inserts with known basis material densities were extracted for training samples. Numerically simulated insert materials with various shapes increased diversity of training samples. Generalizability of AGATE was evaluated using CT images from phantoms and patients. In phantoms, material decomposition accuracy was estimated using mean‐absolute‐percent‐error (MAPE), using physical inserts that were not used during the training. Noise power spectrum (NPS) and modulation transfer function (MTF) were compared across phantom sizes and radiation dose levels. Five patients with multiple myeloma underwent dual‐energy CT, with VNCa images generated using a commercial method and AGATE. Two fellowship‐trained musculoskeletal radiologists reviewed the VNCa images (commercial and AGATE) side‐by‐side using a dual‐monitor display, blinded to VNCa type, rating the image quality for focal multiple myeloma lesion visualization using a 5‐level Likert comparison scale (−2 = worse visualization and diagnostic confidence, −1 = worse visualization but equivalent diagnostic confidence, 0 = equivalent visualization and diagnostic confidence, 1 = improved visualization but equivalent diagnostic confidence, 2 = improved visualization and diagnostic confidence). A post hoc assignment of comparison ratings was performed to rank AGATE images in comparison to commercial ones.ResultsAGATE demonstrated consistent material quantification accuracy across phantom sizes and radiation dose levels, with MAPE ranging from 0.7% to 4.4% across all testing materials. Compared to commercial VNCa images, the AGATE‐synthesized VNCa images yielded considerably lower image noise (50–77% noise reduction) without compromising noise texture or spatial resolution across different phantom sizes and two radiation doses. AGATE VNCa images had markedly reduced area under NPS curves and maintained NPS peak frequency (0.7 lp/cm to 1.0 lp/cm), with similar MTF curves (50% MTF at 3.0 lp/cm). In patients, AGATE demonstrated reduced image noise and artifacts with improved delineation of focal multiple myeloma lesions (all readers comparison scores indicating improved overall diagnostic image quality [scores 1 or 2]).ConclusionsAGATE demonstrated reduced noise and artifacts in VNCa images and ability to improve visualization of bone marrow lesions for assessing multiple myeloma.