The Effect of Radioiodine on the Intima Media Thickness of the Carotid Artery

Abstract

Aim: The radiation can induce vessel injury. The result of this injury can be severe and life-threatening. There are a few studies demonstrating an increase in intima-media thickness (IMT) of the common carotid artery (CCA) after radiotherapy, especially in head and neck cancers. We evaluated the effect of I-131 to the IMT of the CCA in the patients who were treated for hyperthyroidism.Methods: 38 patients (25M, 13W) referred to our department for radioiodine treatment with the diagnosis of nodular goitre (25 patients) and diffuse hyperplasia (Graves disease (GD), 13 patients) were included to the prospective study. An USG was performed for all the patients before therapy, 3, 6 and 12 months after radioiodine therapy in order to measure IMT of CCA and the femoral artery (FA). The IMT was measured at the level of proximal part of bulbus anteriorly on the left and right side. The IMT of FA was measured just before the bifurcation.Results: There was a statistically significant increase in IMT of both CCA and FA bilaterally in nodular hyperthyroid patients. However, in the patients with Graves disease, there was only statistically significant increase in the left IMT of CCA at 0-3rd, 0-6th month measurements and in the right IMT of FA at 0-3rd month measurements. Conclusion: Though the limitation of the study is the interobserver and intraobserver variability, it was seen that I-131 therapy might affect the IMT of CCA in the patients with NG. I-131 effect on the IMT of CCA in patients with nodular goitre was higher than the IMT of CCA in patients with GD. I-131 effect on the IMT of CCA might be due to administered dose and adjacency. The interesting point of our study was the increased thickness of IMT in FA. We think that the increase in IMT is due to the systemic effect of radioactivity circulating in the blood vessel. I-131 effect on the IMT of FA in patients with nodular goitre was higher than the IMT of FA in the patients with GD due to I-131 uptake of thyroid gland. Because I-131 uptake was lower in patients with nodular goitre, I-131 in systemic circulation was higher.Conflict of interest:None declared.

Radioiodine Therapy Does Not Change the Atherosclerotic Burden of the Carotid Arteries

“…The main results of no change in CIMT are in contrast to those of Surucu et al ( 13 ), who followed 38 hyperthyroid RAI-treated patients for one year and found an increased CIMT (approximately 0.05 mm) after just three months. This difference may be explained by several factors.…”

“…Accurate dosimetry might have increased the strength of the study by allowing the calculation of a dose–response relationship. However, in the study by Surucu et al ( 13 ), there was no correlation between iodine uptake at 4 and 24 hours and changes in CIMT ( 13 ). Furthermore, individual radiosensitivity of the arteries as well as the thyroid may exist but cannot yet be predicted.…”

“…This difference may be explained by several factors. The current study used a semi-automatic determination of CIMT in one video clip covering a whole cardiac cycle, whereas Surucu et al ( 13 ) used a static image and manually positioned electronic calipers, thus introducing a risk of bias ( 29 ). Additionally, this study scanned most of the patients in an area of laminar flow in the carotid artery, while Surucu et al ( 13 ) measured CIMT near the carotid bulb, an area more prone to atherosclerotic changes due to high flow and turbulence ( 30 , 31 ).…”

“…Several studies have shown an increase in CIMT, plaque, and stroke in head and neck cancer patients treated with radiation therapy ( 12 ). Furthermore, a recent study showed increased CIMT three months after RAI treatment, indicating that these changes might be induced early on by radiation from RAI ( 13 ). However, this study included only hyperthyroid patients, and looked solely at the early effects of radiation (one year follow-up).…”

Temporary changes in neutrophil-to-lymphocyte, platelet-to-lymphocyte ratios, and mean platelet volume reflecting the inflammatory process after radioiodine therapy

“…However, changes in NLR, PLR, and MPV can be related to the systemic effect of RAI therapy. Consistent with this finding, Sürücü et al [31] reported a significant increase in intima media thickness of both the carotid and the femoral arteries after low-dose RAI in nodular goiter hyperthyroid patients and they considered that these changes in the femoral artery might be a result of the systemic effect of RAI.…”