Powell, Garret M.

ABSTRACT Purpose Abnormal restrictions at myofascial interfaces are a key factor in chronic low back pain (CLBP) with myofascial pain syndrome (MPS), but no established imaging method exists for quantitative assessment. This pilot study evaluated the clinical feasibility of MR elastography (MRE)‐based slip interface imaging (SII) for visualizing myofascial mobility in CLBP‐MPS patients versus age−/sex‐/BMI‐matched healthy participants. A new SII biomarker, maximal normalized displacement discontinuity (), was introduced, and the previously developed normalized octahedral shear strain (NOSS) map was used for comparison. Preliminary assessments of vibration‐frequency effects, repeatability, and group differences in inter‐muscular mobility were conducted. Methods MRE was conducted at 30, 60, and 90 Hz to compare with NOSS for visualizing inter‐muscular slip interfaces at the quadratus lumborum‐erector spinae (QL‐ES) and erector spinae‐multifidus (ES‐M) muscle boundaries at L3‐L4. Repeatability of and NOSS was assessed at 30 Hz (identified as the best‐performing frequency) using within‐subject coefficients of variation and a linear mixed‐effects model from within‐ and between‐day scans. Clinical feasibility was then assessed via Wilcoxon rank‐sum tests in six CLBP‐MPS patients and matched controls. Results at 30 Hz exhibited superior delineation of slip interfaces compared to higher frequencies and NOSS. demonstrated significantly lower variation and better repeatability than NOSS. Healthy participants showed continuous, well‐defined slip interfaces, whereas CLBP‐MPS patients displayed disrupted interfaces with significant mobility reduction at L4 ES‐M. Conclusion SII with lower vibration frequency and map enhances visualization of lower back myofascial mobility and shows potential for assessing differences between healthy individuals and CLBP‐MPS patients.

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.

AbstractPurposeAbnormal adherence at functional myofascial interfaces is hypothesized as an important phenomenon in myofascial pain syndrome. This study aimed to investigate the feasibility of MR elastography (MRE)–based slip interface imaging (SII) to visualize and assess myofascial mobility in healthy volunteers.MethodsSII was used to assess local shear strain at functional myofascial interfaces in the flexor digitorum profundus (FDP) and thighs. In the FDP, MRE was performed at 90 Hz vibration to each index, middle, ring, and little finger. Two thigh MRE scans were performed at 40 Hz with knees flexed and extended. The normalized octahedral shear strain (NOSS) maps were calculated to visualize myofascial slip interfaces. The entropy of the probability distribution of the gradient NOSS was computed for the two knee positions at the intermuscular interface between vastus lateralis and vastus intermedius, around rectus femoris, and between vastus intermedius and vastus medialis.ResultsNOSS map depicted distinct functional slip interfaces in the FDP for each finger. Compared to knee flexion, clearer slip interfaces and larger gradient NOSS entropy at the vastus lateralis–vastus intermedius interface were observed during knee extension, where the quadriceps are not passively stretched. This suggests the optimal position for using SII to visualize myofascial slip interface in skeletal muscles is when muscles are not subjected to any additional force.ConclusionThe study demonstrated that MRE‐based SII can visualize and assess myofascial interface mobility in extremities. The results provide a foundation for investigating the hypothesis that myofascial pain syndrome is characterized by changes in the mobility of myofascial interfaces.

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.

BACKGROUND The advancement of high-resolution imaging and increased clinical experience have led to an increased understanding of the formation and treatment of intraneural ganglion cysts. Nearly all intraneural ganglion cysts in the common peroneal nerve have been reported to arise from a joint connection to the superior tibiofibular joint. The authors have identified four cases of intraneural ganglion cysts arising from the knee joint itself; however, none of these reported cases were well described, documented, or illustrated with high-resolution imaging. OBSERVATIONS Here the authors present the case of an intraneural ganglion cyst arising from the knee joint and causing intermittent weakness and pain. The articular branch to the knee joint was clearly demonstrated on high-resolution magnetic resonance imaging and confirmed at surgical exploration. The patient was treated with articular branch ligation and has had complete resolution of his symptoms without recurrence of the cyst on follow-up imaging. LESSONS This case adds to the mounting evidence that intraneural cyst pathology is dependent on a connection to a synovial joint as stated in the unifying theory of intraneural cyst development.