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Radiother Oncol. 2016 Feb;118(2):315-22. doi: 10.1016/j.radonc.2016.01.011. Epub 2016 Jan 28.

Magnetic resonance imaging of swallowing-related structures in nasopharyngeal carcinoma patients receiving IMRT: Longitudinal dose-response characterization of quantitative signal kinetics.

Author information

1
Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA; The University of Texas Medical School at Houston, USA. Electronic address: Jay.A.Messer@uth.tmc.edu.
2
Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA; Department of Clinical Oncology and Nuclear Medicine, Faculty of Medicine, University of Alexandria, Egypt. Electronic address: asmohamed@mdanderson.org.
3
Department of Head and Neck Surgery, The University of Texas MD Anderson Cancer Center, Houston, USA.
4
Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA; Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, USA.
5
Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA.
6
Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA; The University of Texas Medical School at Houston, USA.
7
Department of Diagnostic Imaging, The University of Texas MD Anderson Cancer Center, Houston, USA.
8
Department of Radiology, Harvard Medical School, Boston, USA.
9
Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, USA.
10
Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA. Electronic address: cdfuller@mdanderson.org.

Abstract

BACKGROUND:

We aim to characterize serial (i.e., acute and late) MRI signal intensity (SI) changes in dysphagia-associated structures as a function of radiotherapy (RT) in nasopharyngeal cancer (NPC) patients.

MATERIALS AND METHODS:

We retrospectively extracted data on 72 patients with stage III-IV NPC treated with intensity-modulated RT (IMRT). The mean T1- and T2-weighted MRI SIs were recorded for the superior pharyngeal constrictor (SPC) and soft palate (SP) at baseline, early-after IMRT, and last follow up, with normalization to structures receiving <5 Gy.

RESULTS:

All structures had a significant increase in T2 SIs early after treatment, irrespective of the mean dose given. At last follow-up, the increase in T2 SI subsided completely for SPC and partially for SP. The T1 SI did not change significantly in early follow-up images of both structures; on late follow-up, patients with mean doses >62.25 Gy had a significant decrease in the corresponding T1 SI for SPC (1.6 ± 0.4 vs. 1.3 ± 0.4, P=0.007) but decreased non-significantly for SP.

CONCLUSIONS:

Serial MRI acquisitions enable the identification of both early and late radiation-induced changes in swallowing structures after definitive IMRT for NPC. Dose dependent decrease in late T1 SI is associated with higher RT doses to the superior pharyngeal constrictor muscle; while dose independent increase in SI for both structures in early post-RT T2 images is observed and subsides after therapy. Further efforts will seek to elucidate the relationship between dose-dependent muscle SI changes and functional alteration of swallowing muscles.

KEYWORDS:

Dose–response; Dysphagia; IMRT; Magnetic resonance imaging; Nasopharyngeal carcinoma; Superior pharyngeal constrictor

PMID:
26830697
PMCID:
PMC4794348
DOI:
10.1016/j.radonc.2016.01.011
[Indexed for MEDLINE]
Free PMC Article

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