BACKGROUND: To evaluate the technical success and patient safety of magnetic resonance-guided percutaneous microwave coagulation (MR-guided PMC) for breast malignancies.
METHODS: From May 2018 to December 2019, 26 patients with breast tumors measuring 2 cm or less were recruited to participate in a prospective, single-institution clinical study. The primary endpoint of this study was the evaluation of treatment efficacy for each patient. Histochemical staining with α-nicotinamide adenine dinucleotide and reduced (NADH)-diaphorase was used to determine cell viability following and efficacy of PMC. The complications and self-reported sensations from all patients during and after ablation were also assessed. The technical success of the PMC procedure was defined when the area of the NADH-diaphorase negative region fully covered the hematoxylin-eosin (H&E) staining region in the tumor.
RESULTS: All patients had a complete response to ablation with no residual carcinoma on histopathological specimen. The mean energy, ablation duration, and procedure duration per tumor were 36.0 ± 4.2 kJ, 252.9 ± 30.9 S, and 104.2 ± 13.5 min, respectively. During the ablation, 14 patients underwent prolonged ablation time, and 1 patient required adjusting of the antenna position. Eleven patients had feelings of subtle heat or swelling, and 3 patients experienced slight pain. After ablation, one patient took two painkillers because of moderate pain, and no patients had postoperative oozing or other complications after PMC. Induration around the ablation area appeared in 16 patients.
CONCLUSIONS: MR-guided PMC of small breast tumors is feasible and could be applied in clinical practice in the future.
UNASSIGNED: MR-guided PMC of small breast tumors is feasible and could be applied in clinical practice in the future.
CONCLUSIONS: • MR-guided PMC of small breast tumors is feasible. • PMC was successfully performed for all patients. • All patients were satisfied with the final cosmetic result.

OBJECTIVE: This study assessed the therapeutic efficacy of postoperative magnetic resonance (MR)-guided interstitial 125 I seed implantation for treatment of oral and maxillofacial malignant tumors.
METHODS: A total of 127 patients with oral or maxillofacial malignant tumors were included in this study who received interstitial 125 I treatment after the surgery resection. Before implantation, all the patients received MR scans to assess the lesion scope, extent, and nature. 125 I implantation target regions were based on the pre-operative imaging. 125 I seeds were delivered to target regions via puncture needles under the real-time guidance of MR. Computed tomography (CT)or MR was performed immediately after implantation and again every 3 months later.
RESULTS: After successful 125 I implantation, all patients were also examined regularly to detect tumor recurrence, lymphatic, and distant metastases. To date, CT or MR verification showed that 13/127 patients experienced tumor recurrence or lymphatic metastasis or distant metastasis. No seeds migration was observed, no serious treatment-related complications affected patient quality of life, and no important organ (such as major cervical vessels, spinal cord, etc.) injuries were observed.
CONCLUSIONS: Our results show that MR-guided 125 I implantation is an effective approach to site-specific treatment for oral and maxillofacial tumor, which could potentially reduce postoperative complications and tumor recurrence rates, increase patient survival, and improve quality of life.

Magnetic resonance (MR)-guided microwave ablation is a well-developed technique for the treatment of tumors, especially hepatic carcinomas. However, there are no detailed reports on the changes in the MR images and histology observed after the ablation. This study aimed to dynamically map the pathological changes after ablation and the changes occurring on MR images.
We performed MR-guided microwave ablation in 10 Wuzhishan pigs and obtained an MR scan immediately after ablation (0 weeks) and at 1, 2, 3, and 4 weeks after ablation. We compared the ablation assessed on MR images to tissue specimens obtained during follow-up.
We found no significant difference in the ablation size between MR images and tissue specimens; the mean length and width of the ablated zone were 4.27 cm and 2.42 cm, respectively, on MR images and 4.26 cm and 2.45 cm, respectively, on specimens (P > 0.05). Immediately after ablation, carbonization and cavities were observed in the center of the ablation zone. Surrounding layer cells were necrotic but maintained their original shapes. The outermost layer was inflamed, but gradually showed fibrotic characteristics. The MR images accurately reflected the exact histological tissue changes after the ablation procedure.
The dynamic imaging and pathological features of liver ablation outlined in this study will provide a useful reference for patient follow-up after MR-guided microwave ablation.

BACKGROUND: Owing to the high risk of abscess drainage by craniotomy, imaging-guided stereotactic aspiration is considered an ideal choice in the management of brain abscesses. Interventional magnetic resonance imaging (MRI) represents a valuable technique for the treatment of brain abscess as a guiding modality.
OBJECTIVE: To evaluate the safety and efficacy of an interventional MRI system in performing the procedure.
METHODS: Thirteen brain abscesses in 11 patients were treated with percutaneous aspiration. All procedures were performed solely under the guidance of a 0.23-T open-configuration MRI scanner with optical tracking. Clinical and imaging follow-up was at 1 week, 1 month, 3 months, and 6 months. The changes of abscess, MRI features, and clinical symptoms were recorded. Procedure efficacy and safety were evaluated by success rate, procedure time, decrease of abscess, recovery rate, and complication. Descriptive statistical analysis was performed.
RESULTS: MRI-guided stereotactic aspirations were performed successfully in 13/13 (100%) abscesses. The mean operating time was 70 min (range, 45-100 min). Follow-up MRI at 1 week after the procedure showed average reduction of abscesses by 60% (2.1/3.5). And the abscesses continued to get smaller by up to 89.7% (3.14/3.5) at 1-month follow-up. All cavities resolved at the end of the 6-month follow-up period. The recovery rate was 100% for fever, headache, vomiting, papilledema, meningismus, altered sensorium, 75% (3/4) for hemiparesis, and 83.3% (5/6) for epilepsy. There were no complications.
CONCLUSIONS: Punctures of brain abscesses with subsequent aspiration can be performed safely and efficiently by monitoring the procedure using an open interventional MRI system.