MR‐guided simulation is superior than FDG/PET‐guided simulation for local control in nasopharyngeal cancer patients treated with intensity‐modulated radiotherapy

Abstract

Background MRI and PET/CT scans are the main supportive methods for nasopharyngeal cancer (NPC) for staging and planning. The aim of this study is to compare MRI and PET/CT scanning in terms of survival in patients with NPC who had MRI or PET/CT‐simulated radiotherapy planning. Methods Pathological diagnosed nonkeratinized undifferentiated type and stage II‐IVA 91 NPC patients with treated intensity‐modulated radiotherapy plus chemotherapy were scanned. The patients were immobilized by a customized thermoplastic mask for fusion images both MRI scans and PET/CT scans. CTVs were created via MR‐guided simulation and PET/CT‐guided simulation. Results PET/CT‐guided simulation was performed with 44 patients (56.4%) and MR‐guided simulation was performed with 34 patients (43.6%). Local recurrence‐free survival (LRFS) of patients was 68.1 months. LRFS of patients with PET/CT‐guided simulation was 59.9, while LRFS of patients with MR‐guided was 66.9 months. There was a statistically significant difference between groups (P = .03). In the subgroup analyses, the patients were assessed by dividing into the three groups for the T1‐T2 stage, T‐3 stage, and T‐4 stage. In the patients with T1‐T2 stage, 5‐year LRFS rates were found %74.4 for PET/CT‐guided simulation and %83.3 for MR‐guided simulation. There was no statistically significant difference between groups (P = .33). In the patients with T‐3 stage, 5‐year LRFS rates were found %55.6 for PET/CT‐guided simulation and %83.3 for MR‐guided simulation. There was not a statistically significant difference between groups (P = .59). In the patients with T‐4 stage, 5‐year LRFS rates were found %42.2 for PET/CT‐guided simulation and %85.1 for MR‐guided simulation. The difference between groups was found to be statistically significant (P = .04). Conclusion In this study, we founded that MR‐guided simulation has better than PET/CT‐guided simulation for LRFS.

Clinical implementation of magnetic resonance imaging simulation for radiation oncology planning: 5 year experience

“…Our study is significant as it details protocols and processes developed in-house to deliver radiation planning scans at diagnostic quality, improved over 5 years of experience, and with almost nominally nine-thousand MR scans. Although there are guidelines and recommendations for the development and implementation of a MR-planning program [8,9,13], and image acquisition protocols are available for specific sites [4,[14][15][16][17][18][19][20][21][22], very few reports have focused on describing clinical implementation experience with comprehensively detailing MR-planning programs [23].…”

“…In general, the method offers a high signal-to-noise ratio and contrast-to-noise ratio with spatial resolutions on the order of 1.5 mm, but it is the differential contrast between tissue types that contributes to its greater utility in imaging over CT-scanning. Due to these advantages, the MR has become the method of choice for improved target delineation in radiation oncology [ 2 , 4 ].…”

A multicenter retrospective analysis of patients with nasopharyngeal carcinoma treated in IMRT era from a nonendemic population: Turkish Society for Radiation Oncology Head and Neck Cancer Group Study (TROD 01‐001)

“…Nasopharyngeal carcinoma incidence in Turkey between 2014 and 2017 was 1.2/100 000 in men and 0.4/100 000 in women 16 . The availability of high‐tech radiotherapy facilities in the country has increased significantly over the past decade, and IMRT has become the most widely used technique in radiotherapy centers nationwide 17 . This multicentric retrospective study is the most comprehensive case series of nasopharyngeal carcinoma treated with IMRT to date in Turkey.…”

“…Reasons for re-planning were weight loss in 33 (38.4%), tumor shrinkage in 15 (17.4%), and both in 28 (32.6%) patients. The median radiotherapy fraction time for adaptive planning was 22 (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28). IGRT was executed using daily/ weekly CBCT (19.4%), kV-kV (6%), and both (41.2%).…”