ABSTRACT
Magnetic resonance imaging (MRI) is a technology with no radiation and high resolution of soft tissues. Therefore, MRI-guided radiotherapy has become a hot spot in the field of radiotherapy. It is of great importance to accurately delineate the targets in radiation oncology. Currently, the delineation of targets is mostly completed by manual segmentation, which is time-consuming, subjective and inconsistent. Automatic segmentation can improve the efficiency and consistency without sacrificing the accuracy of segmentation. In this article, the automatic segmentation methods of MRI applied in radiotherapy were reviewed. The goals, challenges and methods of automatic segmentation for different radiotherapy sites including prostate, nasopharyngeal carcinoma, brain tumors and other organs were analyzed and discussed.
ABSTRACT
Purpose: The purpose of this study is to study the clinical outcomes of different types of magnetic resonance (MR)-guided ablation for the treatment of liver tumors by performing a systematic review and pooled analysis. Materials and Methods: A comprehensive literature search was performed for clinical trials published from January 1997 to October 2019 in PubMed, the Web of Science, Embase, and the Cochrane Library. Pooled analyses were performed to obtain the complete ablation (CA), complication, progression-free survival (PFS), and overall survival (OS) rates. Results: Thirty studies were eligible, including four studies on MR-guided microwave ablation (MWA); 14 studies on MR-guided radiofrequency ablation (RFA); one study on both MR-guided MWA and RFA; eight studies on MR-guided, laser-induced thermotherapy (LITT); two studies on MR-guided percutaneous cryoablation (PC); and one study on MR-guided percutaneous ethanol injection (PEI). The CA rates in patients who underwent RFA, MWA, LITT, PC, and PEI were 95.60%, 98.86%, 77.78%, 47.92%, and 85.71%, respectively. The most frequent complications were pain (27.66%, 13/47) and postablation syndrome (27.66%, 13/47) in the PC group; pleural effusion (8.11%, 119/1,468) and subcapsular hematoma (2.25%, 33/1,468) in the LITT group; pleural effusion (2.67%, 2/75) in the MWA group; and subcapsular hematoma (4.18%, 20/478) and post-ablation syndrome (2.93%, 14/478) in the RFA group. There were few studies reporting PFS and OS. Conclusions: MR-guided ablation is a practicable alternative treatment for liver tumors, especially MR-guided RFA and MWA, which have high rates of CA and low occurrences of complications
ABSTRACT
Context: It is necessary to explore a minimally invasive, effective, and efficient treatment for those lung cancer patients who are poor candidates for surgery. Aim: This study aimed to investigate the application of microwave ablation (MWA) in the treatment of lung cancer. Settings and Design: A total of 43 patients with 44 pulmonary lesions were examined following identical procedures before being randomly divided into two groups. The experimental group consists of 17 patients with a total of 18 pulmonary lesions, while the control group consists of 26 patients with a total of 26 pulmonary lesions. Materials and Methods: The experimental group was treated using magnetic resonance imaging (MRI)-guided MWA while the control group was treated using computer tomography (CT)-guided MWA. A transverse relaxation time-turbo spin echo (T2-TSE) sequence was used for signal collection in the experimental group to determine puncture location and microwave needle position while T2-TSE, T1-turbo field echo, and diffusion-weighted MRI (DWI) sequences were used for timely efficacy evaluation. Whereas in the control group, CT axial scanning was performed to serve similar purposes. Statistical Analysis Used: A nonparametric Wilcoxon test, median (M [25%, 75%]). Results: All of the 44 lesions were successfully located on the first attempt. The mean time for scanning and locating lung lesions under MRI and CT guidance were 64.53 and 42.96 min, the mean times of positioning were 12 and 18 min, and the mean durations of MWA were 12.48 and 15.06 min, respectively. Conclusions: As a minimally invasive method for treating lung tumors, MRI-guided MWA requires fewer localization scans, a shorter MWA duration, no radiation, real-time observation of the curative effect, and it prevents overtreatment