This month (Feb. 2009), there is an article in AJNR regarding differentiating cold thryoid nodules as benign vs. malignat on DWI. link: http://www.ajnr.org/cgi/content/full/30/2/417. A similar article by Bozgeyik et al (abstract below) appeared in the March 2009 issue of ‘Neuroradiology’ (see below). The current article in AJNR reports that malignant thyroid nodules demonstrated increased ADC values compared with benign ones, whereas the article in Neuroradiology reports lower ADC maps for malignancy. Similarly the article by Razek et al in March, 2008 AJNR (link: http://www.ajnr.org/cgi/content/full/29/3/563) reported lower ADCs for malignant nodules.
Does anyone have any thoughts on possible reasons for the discrepancies?
Neuroradiology 2009 Mar;51(3):193-8. Epub 2009 Jan 23.
Diffusion-weighted MR imaging of thyroid nodules.
Department of Radiology, Faculty of Medicine, Firat University, 23119, Elazig, Turkey, bozgeyik4@hotmail.com.
INTRODUCTION: The purpose of our study was to determine the diagnostic role of diffusion-weighted imaging (DWI) in the differentiating of malignant and benign thyroid nodules by using fine needle aspiration biopsy cytology criteria as a reference standard. The apparent diffusion coefficient (ADC) values of the normal-looking thyroid parenchyma were also evaluated both in normal patients and in patients with nodules. METHODS: Between March 2007 and February 2008, 76 consecutive patients with ultrasound-diagnosed thyroid nodules and 20 healthy subjects underwent diffusion-weighted MR imaging by using single-shot spin echo, echo planar imaging. A total of 93 nodules were included in the study using the following b factors 100, 200, and 300 mm(2)/s. ADC values of thyroid nodules and normal area in all subjects were calculated and compared using suitable statistical analysis. RESULTS: Mean ADC values for malignant and benign nodules were and for b-100 factor, and for b-200, for b-300, respectively. Mean ADC values of malignant nodules were lower than benign nodules. There were significant differences in ADC values between benign and malignant nodules. ADC values among normal-appearing thyroid parenchyma of patients and normal-appearing thyroid parenchyma of healthy subjects were insignificant at all b factors. CONCLUSION: Benign nodules have higher ADC values than malignant ones. DWI may be helpful in differentiating malign and benign thyroid nodules.
