Detection of Thyroid Shrinkage in Post-radiation Head-and-Neck

Cancer Patients with Ultrasound Chelsea Chen, Xiaofeng Yang, Tatiana Han, Faisal Khosa, Srini Tridandapani, Jonathan Beitler, David Yu, Tian Liu

Winship Cancer Institute, Emory University, Atlanta, Georgia

Purpose

Introduction

To establish ultrasound as a reliable imaging

modality to detect thyroid volume change in

patients following radiotherapy treatment for

head-and-neck cancers.

• Radiotherapy is an important treatment modality

for head-and-neck cancers. However, radiation-

induced thyroid dysfunction is a debilitating

chronic side-effect that can cause hormonal

unbalance resulting in side effects like heart

disease, obesity, and infertility.

• Thyroid dysfunction is known to be associated

with thyroid volume size. The current thyroid

visualization tool is ultrasound, but this tool is not

used in routine follow ups of head and neck cancer

patients to observe thyroid volume change.

• Inter and intra-observer reliability has yet to be

tested in usage of ultrasound to measure thyroid

volume change.

Conclusion

• Significant differences between pre and post radiation thyroid

volumes were observed in all patients.

• Mean dose to the thyroids correlates with thyroid shrinkage.

• Ultrasound is a safe, cost-effective and reliable imaging modality

to monitor radiation-induced thyroid volume change, which could

serve as a surrogate for post-radiotherapy thyroid dysfunction.

• Eleven post head-and-neck cancer patients (8 male, 3 female) were

enrolled in this IRB approved study. All had received intensity-

modulated radiotherapy with a mean dose of 43.6 ± 17.3 Gy.

• Pre-treatment thyroid volume was obtained using GE CT scanner

as shown in Fig. 1 (voxel 0.8 x 0.8 x 1.0 mm3, field size 512 x 512)

• Post-treatment thyroid volume was scanned with a Sonix Touch

on their follow-up visits (follow-up time: 29.5 ± 5.4 months). Total of

88 images were obtained, 8 from each patient, scanned for the

upper transverse, mid transverse, lower transverse, and sagittal

directions for each lobe, as the patient lay supine. (Fig. 2)

Fig. 1 Transverse CT image of the neck region.

Light blue outlined area is the thyroid.

Fig. 2 Diagram showing directions of

ultrasound scans.

Methods

Ultrasound Measurement of Thyroid Volume

Fig. 4 Thyroid contouring (a) showing Ultrasound image of a patient’s thyroid in the mid

transverse plane (b) Ultrasound image in the sagittal direction of the thyroid

(a)

• Two experienced radiologists manually contoured the thyroids on all

images and one observer did so on 2 occasions, separated by 2

months.

• Dimensions taken were craniocaudal (CC), lateromedial (LM), and

anteroposterior (AP), respectively length, width, and depth.

•The formula, V = π/6 x (CC x LM x AP) was used on the right and left

contoured lobes of each patient separately, and then they were

combined to form a total thyroid volume

Methods

AP

LM

(b)

CC

• The thyroid volume change correlated with the mean

radiation dose to the thyroids (Fig. 3). Using a Pearson

correlation test, our correlation values was 0.68, indicating

moderate positive correlation.

• Higher radiation doses to the thyroid tended to occur

with greater percentage in thyroid volume shrinkage.

• Significant thyroid volume changes were

observed in all patients (Table 1). The

average change in volume from pre-

treatment to post-treatment across all

observations would be approximately 8.0

cm3

Paired t test

p-value =

4.84E-04

Fig 3. Correlation of mean dose of radiation (Gy) to the thyroids

and percent change in thyroid volume at follow-up time.

Pearson Correlation

Coefficient: r = 0.68

Results

References Cheng, S. C., Wu, V. W., Kwong, D. L., Lui, C., Cheng, A. C., Kot, B. C., & Ying, M. T. (2014). Sonographic appearance of thyroid

glands in patients treated with intensity-modulated radiotherapy or conventional radiotherapy for nasopharyngeal carcinoma.

Journal of Clinical Ultrasound J. Clin. Ultrasound, 43(4), 210-223. doi:10.1002/jcu.22222

Lin, Z., Wu, V. W., Lin, J., Feng, H., & Chen, L. (2011). A Longitudinal Study on the Radiation-Induced Thyroid Gland Changes

After External Beam Radiotherapy of Nasopharyngeal Carcinoma. Thyroid, 21(1), 19-23. doi:10.1089/thy.2010.0229

Mahmood, M. H., & Rusli, A. H. (2011). Segmentation and Area Measurement for Thyroid Ultrasound Image. International Journal

of Scientific & Engineering Research, 2(12). Retrieved July 7, 2015.

• The thyroid volumes of inter and intra-reliability study

were shown in Table 2. The inter-observer and intra-

observer variations were not significant (0.48, 0.14)

• There are no significant differences between observations as

indicated by the high p-values, 0.48 and 0.30, thus proving

inter- and intra-observer reliability (Table 3).

Results