High-Intensity Focused Ultrasound Surgery for Tumor Ablation: A Review of Current Applications.

The management of cancer with alternative approaches is a matter of clinical interest worldwide. High-intensity focused ultrasound (HIFU) surgery is a noninvasive technique performed under US or MRI guidance. The most studied therapeutic uses of HIFU involve thermal tissue ablation, demonstrating both palliative and curative potential. However, concurrent mechanical bioeffects also provide opportunities in terms of augmented drug delivery and immunosensitization. The safety and efficacy of HIFU integration with current cancer treatment strategies are being actively investigated in managing primary and secondary tumors, including cancers of the breast, prostate, pancreas, liver, kidney, and bone. Current primary HIFU indications are pain palliation, complete ablation of localized earlystage tumors, or debulking of unresectable late-stage cancers. This review presents the latest HIFU applications, from investigational to clinically approved, in the field of tumor ablation. Keywords: Ultrasound, Ultrasound-High Intensity Focused (HIFU), Interventional-MSK, Interventional-Body, Oncology, Technology Assessment, Tumor Response, MR Imaging © RSNA, 2023.

Whole body MRI with Diffusion Weighted Imaging versus 18F-fluorodeoxyglucose-PET/CT in the staging of lymphomas.

PURPOSE: To assess the diagnostic performance of Whole Body (WB)-MRI in comparison with 18F-Fluorodeoxyglucose-PET/CT (18F-FDG-PET/CT) in lymphoma staging and to assess whether quantitative metabolic parameters from 18F-FDG-PET/CT and Apparent Diffusion Coefficient (ADC) values are related. MATERIALS AND METHODS: We prospectively enrolled patients with a histologically proven primary nodal lymphoma to  undergo 18F-FDG-PET/CT and WB-MRI, both performed within 15 days one from the other, either before starting treatment (baseline) or during treatment (interim). Positive and negative predictive values of WB-MRI for the identification of nodal and extra-nodal disease were measured. The agreement between WB-MRI and 18F-FDG-PET/CT for the identification of lesions and staging was assessed through Cohen's coefficient k and observed agreement. Quantitative parameters of nodal lesions derived from 18F-FDG-PET/CT and WB-MRI (ADC) were measured and the Pearson or Spearman correlation coefficient was used to assess the correlation between them. The specified level of significance was p ≤ 0.05. RESULTS: Among the 91 identified patients, 8 refused to participate and 22 met exclusion criteria, thus images from 61 patients (37 men, mean age 30.7 years) were evaluated. The agreement between 18F-FDG-PET/CT and WB-MRI for the identification of nodal and extra-nodal lesions was 0.95 (95% CI 0.92 to 0.98) and 1.00 (95% CI NA), respectively; for staging it was 1.00 (95% CI NA). A strong negative correlation was found between ADCmean and SUVmean of nodal lesions in patients evaluated at baseline (Spearman coefficient rs = - 0.61, p = 0.001). CONCLUSION: WB-MRI has a good diagnostic performance for staging of patients with lymphoma in comparison with 18F-FDG-PET/CT and is a promising technique for the quantitative assessment of disease burden in these patients.

Focused Ultrasound and External Beam Radiation Therapy for Painful Bone Metastases: A Phase II Clinical Trial.

Background Recent consensus statements and clinical trials have assessed the value of MRI-guided focused ultrasound surgery for pain palliation of bone metastases; however, a comparison with external beam radiation therapy (EBRT) has not been performed. Purpose To compare safety and effectiveness data of MRI-guided focused ultrasound and EBRT in the treatment of bone metastases. Materials and Methods Participants with painful bone metastases, excluding skull and vertebral bodies, were enrolled in a prospective open-label nonrandomized phase II study between January 2017 and May 2019 and underwent either MRI-guided focused ultrasound or EBRT. The primary end point was the overall response rate at 1-month following treatment, assessed via the numeric rating scale (NRS) for pain (0-10 scale, with zero meaning "no pain" and 10 meaning "the worst pain imaginable"). Secondary end points were improvements at 12-month follow-up in NRS and quality of life (QoL) measures, including the Brief Pain Inventory (BPI), QoL-Questionnaire Cancer-15 Palliative Care (QLQ-C15-PAL), and QoL-Questionnaire Bone Metastases-22 (QLQ-BM22) and analysis of adverse events. Statistical analyses, including linear regression, χ2 test, and Student t test followed the per-protocol principle. Results Among 198 participants, 100 underwent MRI-guided focused ultrasound (mean age, 63 years ± 13 [SD]; 51 women), and 98 underwent EBRT (mean age, 65 years ± 14; 52 women). The overall response rates at 1-month follow-up were 91% (91 of 100) and 67% (66 of 98), respectively, in the focused ultrasound and EBRT arms (P < .001), and complete response rates were 43% (43 of 100) and 16% (16 of 98) (P < .001). The mean baseline NRS score was 7.0 ± 2.1 for focused ultrasound and 6.6 ± 2.4 for EBRT (P = .16); at 1-month follow-up, they were reduced to 3.2 ± 0.3 and 5.1 ± 0.3 (P < .001), respectively. QLQ-C15-PAL for physical function (P = .002), appetite (P < .001), nausea and vomiting (P < .001), dyspnea (P < .001), and QoL (P < .001) scores were lower in the focused ultrasound group. The overall adverse event rates were 15% (15 of 100) after focused ultrasound and 24% (24 of 98) after EBRT. Conclusion MRI-guided focused ultrasound surgery and external beam radiation therapy showed similar improvements in pain palliation and quality of life, with low adverse event rates. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Kelekis in this issue.