Abstract
Thyroid nodule is a common disease in clinical practice. The diagnosis of malignant thyroid tumors determines the treatment strategy. Among a number of methods have claimed to help evaluating thyroid nodules, ultrasound is a usable one in spite of several disadvantages (dependent on the physician/technician, incomparable, etc.) and magnetic resonance imaging (MRI) accompanied by quantitative apparent diffusion coefficient (ADC) is a promising diagnostic tool. This study was designed to investigate the usefulness of ADC cut-off values and the protocol of thyroid MRI derived from quantitative diffusion weighted imaging (DWI) in differentiating benign and malignant thyroid nodules. The study was conducted on 93 patients with 128 thyroid nodules, diagnosed and underwent surgery at Hanoi Medical University Hospital. All the patients took thyroid MRI with different b levels (from 200 to 800). ADC value was calculated to each b level, and the statistical tests were conducted with the Statistical Package for Social Sciences (SPSS—Windows and Mac version 20) and STATA 12. The mean ADC with all the b ranging from 200 to 800 of malignant groups was significantly higher than the group of benign lesions (p from <0.001 to 0.01). We chose b = 500 as a standard b-value in the protocol of thyroid MRI. The ADC cut-off point for distinguishing malignant from benign thyroid lesions: 1.7 × 10−3 mm2/s with high accuracy (87.1%, 95% CI: 79.59–92.07%). The study revealed that quantitative diffusion weighted MRI with ADC measurement could potentially quantitatively differentiate between benign and malignant thyroid nodules.
Highlights
Thyroid nodules are a common entity and detected in 4–7% of the population by physical examination alone
Our study was conducted on 93 patients with a total of 128 thyroid nodules, 49 malignant lesions
We suggest with 1.5T magnetic resonance imaging (MRI) machine, it is necessary to find out the most valuable b value to reduce the time of MRI exam
Summary
Thyroid nodules are a common entity and detected in 4–7% of the population by physical examination alone. A higher b-value image comes along with noisier and much darker image (low signal to noise ratio) Most tissues drop their intensity from molecular motion, except for the restricted lesions. All the recent studies share one point of view, the authors highlight the advantages of the diffusion-weighted imaging (on the machines with strong magnetic field) which can measure the accurate value of ADC. The authors still do not reach consensus about several contents, in particular about choosing the optimal b value for MRI exam of thyroid and the correspondent recommended cut-off ADC value to detect the malignant nodule [5]. Our purpose was to estimate the diagnostic value of quantitative DWI and calculate the cut-off ADC value to distinguish benign and malignant thyroid lesions using 1.5T MRI machines on patients with thyroid nodules in Vietnam
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