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Open Access Research

Hippocampal volumes in patients exposed to low-dose radiation to the basal brain. A case–control study in long-term survivors from cancer in the head and neck region

Erik Olsson1, Carl Eckerström1, Gertrud Berg2, Magnus Borga3, Sven Ekholm4, Gudmundur Johannsson5, Susanne Ribbelin6, Göran Starck67, Anna Wysocka6, Elisabet Löfdahl2 and Helge Malmgren8*

Author Affiliations

1 Institute of Neuroscience and Physiology;, Sahlgrenska University Hospital, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden

2 Department of Oncology, Sahlgrenska University Hospital, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden

3 Department of Biomedical Engineering, Linköping University, Linköping, Sweden

4 Department of Imaging Sciences, University of Rochester Medical Center, Rochester, N.Y, USA

5 Department of Endocrinology, Sahlgrenska University Hospital, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden

6 Department of Radiation Physics, Sahlgrenska University Hospital, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden

7 Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden

8 Department of Philosophy, Linguistics and Theory of Science, University of Gothenburg, Gothenburg, Sweden

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Radiation Oncology 2012, 7:202  doi:10.1186/1748-717X-7-202

Published: 29 November 2012

Abstract

Background

An earlier study from our group of long time survivors of head and neck cancer who had received a low radiation dose to the hypothalamic-pituitary region, with no signs of recurrence or pituitary dysfunction, had their quality of life (QoL) compromised as compared with matched healthy controls. Hippocampal changes have been shown to accompany several psychiatric conditions and the aim of the present study was to test whether the patients’ lowered QoL was coupled to a reduction in hippocampal volume.

Methods

Patients (11 men and 4 women, age 31–65) treated for head and neck cancer 4–10 years earlier and with no sign of recurrence or pituitary dysfunction, and 15 matched controls were included. The estimated radiation doses to the basal brain including the hippocampus (1.5 – 9.3 Gy) had been calculated in the earlier study. The hippocampal volumetry was done on coronal sections from a 1.5 T MRI scanner. Measurements were done by two independent raters, blinded to patients and controls, using a custom method for computer assisted manual segmentation. The volumes were normalized for intracranial volume which was also measured manually. The paired t test and Wilcoxon’s signed rank test were used for the main statistical analysis.

Results

There was no significant difference with respect to left, right or total hippocampal volume between patients and controls. All mean differences were close to zero, and the two-tailed 95% confidence interval for the difference in total, normalized volume does not include a larger than 8% deficit in the patients.

Conclusion

The study gives solid evidence against the hypothesis that the patients’ lowered quality of life was due to a major reduction of hippocampal volume.