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AJNR - American Journal of Neuroradiology

Published ahead of print on October 22, 2008
doi: 10.3174/ajnr.A1338

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American Journal of Neuroradiology 30:417-422, February 2009
© 2009 American Society of Neuroradiology

HEAD & NECK

Can Quantitative Diffusion-Weighted MR Imaging Differentiate Benign and Malignant Cold Thyroid Nodules? Initial Results in 25 Patients

C. Schueller-Weidekamm^a, K. Kaserer^c, G. Schueller^a, C. Scheuba^b, H. Ringl^a, M. Weber^a, C. Czerny^a and A.M. Herneth^a

^a Department of Diagnostic Radiology, Medical University of Vienna, Vienna, Austria
^b Department of Surgery, Medical University of Vienna, Vienna, Austria
^c Department of Pathology, Medical University of Vienna, Vienna, Austria

Please address correspondence to Claudia Schueller-Weidekamm, MD, Department of Diagnostic Radiology, Medical University of Vienna, Waehringer Guertel 18–20, Vienna A-1090, Austria; e-mail: claudia.schueller-weidekamm{at}meduniwien.ac.at

BACKGROUND AND PURPOSE: The characterization of cold nodules of the thyroid gland is mandatory because approximately 20% of these nodules are of malignant origin. The purpose of this study was to evaluate the distinction of cold thyroid nodules by using quantitative diffusion-weighted MR imaging (DWI).

MATERIALS AND METHODS: In 25 patients with cold nodules on scintigraphy and suggestive findings at fine-needle aspiration, thyroid carcinoma was suggested. In these patients, cold nodules and the normal parenchyma of the contralateral thyroid lobe were prospectively investigated with quantitative DWI (echo-planar imaging sequence; maximum b-value, 800 s/mm²) before surgery. The differences in the mean apparent diffusion coefficient (ADC) values in benign and malignant nodules were tested by using a Mann-Whitney U test.

RESULTS: Histologically, there were 20 carcinomas with a minimum size of 8 mm and 5 adenomas. The mean ADC values (in 10^–3 mm²/s) differed significantly among carcinoma, adenoma, and normal parenchyma (P < .05). The ranges (95% confidence interval) of the ADC values for carcinoma (2.43–3.037), adenoma (1.626–2.233), and normal parenchyma (1.253–1.602) showed no overlap. When an ADC value of 2.25 or higher was used for predicting malignancy, the highest accuracy of 88%, with 85% sensitivity and 100% specificity, was obtained.

CONCLUSIONS: Quantitative DWI seems to be a feasible tool with which to differentiate thyroid carcinomas from adenomas; however, further studies are required including larger numbers of patients to confirm our results.