What happens to brain outside the thermal ablation zones? An assessment of needle-based therapeutic ultrasound in survival swine.

BACKGROUND: In stereotactic radiosurgery, isodose lines must be considered to determine how surrounding tissue is affected. In thermal ablative therapy, such as laser interstitial thermal therapy (LITT), transcranial MR-guided focused ultrasound (tcMRgFUS), and needle-based therapeutic ultrasound (NBTU), how the surrounding area is affected has not been well studied. OBJECTIVE: We aimed to quantify the transition zone surrounding the ablation core created by magnetic resonance-guided robotically-assisted (MRgRA) delivery of NBTU using multi-slice volumetric 2-D magnetic resonance thermal imaging (MRTI) and subsequent characterization of the resultant tissue damage using histopathologic analysis. METHODS: Four swine underwent MRgRA NBTU using varying duration and wattage for treatment delivery. Serial MRI images were obtained, and the most representative were overlaid with isodose lines and compared to brain tissue acquired postmortem which underwent histopathologic analysis. These results were also compared to predicted volumes using a finite element analysis model. Contralateral brain tissue was used for control data. RESULTS: Intraoperative MRTI thermal isodose contours were characterized and comprehensively mapped to post-operative MRI images and qualitatively compared with histological tissue sections postmortem. NBTU 360° ablations induced smaller lesion volumes (33.19 mm3; 120 s, 3 W; 30.05 mm3, 180 s, 4 W) versus 180° ablations (77.20 mm3, 120 s, 3 W; 109.29 mm3; 180 s; 4 W). MRTI/MRI overlay demonstrated the lesion within the proximal isodose lines. The ablation-zone was characterized by dense macrophage infiltration and glial/neuronal loss as demonstrated by glial fibrillary acidic protein (GFAP) and neurofilament (NF) absence and avid CD163 staining. The transition-zone between lesion and normal brain demonstrated decreased macrophage infiltration and measured ∼345 microns (n - 3). We did not detect overt hemorrhages or signs of edema in the adjacent spared tissue. CONCLUSION: We successfully performed MRgRA NBTU ablation in swine and demonstrated minimal histologic changes extended past the ablation-zone. The lesion was characterized by macrophage infiltration and glial/neuronal loss which decreased through the transition-zone.

Predicting ablation zones with multislice volumetric 2-D magnetic resonance thermal imaging.

BACKGROUND: High-intensity focused ultrasound (HIFU) serves as a noninvasive stereotactic system for the ablation of brain metastases; however, treatments are limited to simple geometries and energy delivery is limited by the high acoustic attenuation of the calvarium. Minimally-invasive magnetic resonance-guided robotically-assisted (MRgRA) needle-based therapeutic ultrasound (NBTU) using multislice volumetric 2-D magnetic resonance thermal imaging (MRTI) overcomes these limitations and has potential to produce less collateral tissue damage than current methods. OBJECTIVE: To correlate multislice volumetric 2-D MRTI volumes with histologically confirmed regions of tissue damage in MRgRA NBTU. METHODS: Seven swine underwent a total of 8 frontal MRgRA NBTU lesions. MRTI ablation volumes were compared to histologic tissue damage on brain sections stained with 2,3,5-triphenyltetrazolium chloride (TTC). Bland-Altman analyses and correlation trends were used to compare MRTI and TTC ablation volumes. RESULTS: Data from the initial and third swine's ablations were excluded due to sub-optimal tissue staining. For the remaining ablations (n = 6), the limits of agreement between the MRTI and histologic volumes ranged from -0.149 cm3 to 0.252 cm3 with a mean difference of 0.052 ± 0.042 cm3 (11.1%). There was a high correlation between the MRTI and histology volumes (r2 = 0.831) with a strong linear relationship (r = 0.868). CONCLUSION: We used a volumetric MRTI technique to accurately track thermal changes during MRgRA NBTU in preparation for human trials. Improved volumetric coverage with MRTI enhanced our delivery of therapy and has far-reaching implications for focused ultrasound in the broader clinical setting.

Spinal Cord Stimulation to Treat Low Back Pain in Patients With and Without Previous Spine Surgery.

OBJECTIVES: Little is known about the effects of spinal cord stimulation (SCS) on chronic low back pain (CLBP) patients with no history of previous spine surgery. Using our prospectively collected database, we evaluate improvements in patients with and without previous spine surgery one-year post SCS implantation. MATERIALS AND METHODS: Subjects completed outcome metrics pre-operatively and one-year post-implantation including Numeric Rating Scale (NRS), McGill Pain Questionnaire (MPQ), Oswestry Disability Index (ODI), Beck's Depression Inventory (BDI), and Pain Catastrophizing Scale (PCS). RESULTS: We enrolled 134 patients; 82 patients had previous spine surgery and 52 patients did not. At one-year post-SCS implantation, patients with previous spine surgery showed improvements in worst pain experienced, least pain experienced, average pain experienced, pain felt currently, MPQ, MPQ sensory, MPQ affective, PCS, PCS helplessness, PCS rumination, PCS magnification, ODI, and BDI scores (p < 0.001, p = 0.005, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p = 0.03, p = 0.01, p = 0.02, p < 0.001, p = 0.05, p < 0.001, p = 0.017, respectively). Likewise, patients without previous spine surgery showed improvements in worst pain experienced, least pain experienced, average pain experienced, pain felt currently, MPQ, MPQ sensory, PCS, PCS helplessness, PCS rumination, PCS magnification, ODI, and BDI scores (p < 0.001, p = 0.005, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p = 0.008, p < 0.001, p < 0.001, respectively). Patients without previous spine surgery showed greater improvements for average pain PCS helplessness (p = 0.01). CONCLUSIONS: Patients with and without previous spine surgery showed similar improvements in pain intensity, pain quality, feelings of rumination and magnification, functional disability, and depression severity. SCS can improve CLBP regardless of whether patients have had previous spine surgery.

The Impact of Multidisciplinary Conferences on Healthcare Utilization in Chronic Pain Patients.

Approximately 100 million adults in the United States have chronic pain, though only a subset utilizes the vast majority of healthcare resources. Multidisciplinary care has been shown to improve outcomes in a variety of clinical conditions. There is concern that multidisciplinary care of chronic pain patients may overwhelm existing resources and increase healthcare utilization due to the volume of patients and the complexity of care. We report our findings on the use of multidisciplinary conferences (MDC) to facilitate care for the most complex patients seen at our tertiary center. Thirty-two of nearly 2,000 patients seen per year were discussed at the MDC, making up the top 2% of complex patients in our practice. We evaluated patients' numeric rating score (NRS) of pain, medication use, hospitalizations, emergency department visits, and visits to pain specialists prior to their enrollment in MDC and 1 year later. Matched samples were compared using Wilcoxon's signed rank test. Patients' NRS scores significantly decreased from 7.64 to 5.54 after inclusion in MDC (p < 0.001). A significant decrease in clinic visits (p < 0.001) and healthcare utilization (p < 0.05) was also observed. Opioid and non-opioid prescriptions did not change significantly (p = 0.43). 83% of providers agreed that MDC improved patient care. While previous studies have shown the effect of multi-disciplinary care, we show notable improvements with a team established around a once-a-month MDC.

Impact of a Wireless System Upon Verbal Communication in a Simulated Robotic Operating Theater.

OBJECTIVE: To compare the efficacy of communication via the standard Da Vinci Si speaker system with a wireless, hands-free audio system in a prospective blinded study. METHODS: Nine hundred and sixty surgical phrases were spoken in a simulated robotic operating room (OR), including 480 phrases expressed via the Da Vinci Si speakers and 480 phrases expressed through a wireless, hands-free system. Using a dual console robotic system, communication was evaluated. Wireless headsets were given to the console and assistant robotic console surgeons, bedside assistant, anesthesiologist, and circulating nurse. An accurate response was defined as hearing the phrase correctly and transcribing it on a data sheet. The primary outcome was the number of correct phrases recorded during the study and secondary outcomes included subjective clarity and effectiveness of communication reported using a Likert scale. RESULTS: Overall, the wireless, hands-free system increased the accuracy of communication (390/480 [81.3%]) compared to the conventional robotic system (310/480 [64.4%]; P <.001). The bedside assistant, anesthesiologist, and circulating nurse had significantly fewer correct phrases recorded than the assistant robotic console surgeon when using the robotic speakers (P <.05 for all). In contrast, there were no significant differences in the number of correct phrases recorded between different positions when using the wireless system. Subjectively, the wireless system resulted in improved clarity and effectiveness of communication (P = .021; P <.001, respectively). CONCLUSION: Robotic operating systems have intrinsic barriers to effective communication between the surgeon and the rest of the operating room team. Improved communication could reduce surgical errors and improve patient safety.