Application Of DWI And APT Imaging Im Differential Diagnosis Of Benign And Malignant Thyroid Gland

BackgroundThyroid nodules are common and are found in up to 65%of the general population.Surgeons and radiologists are often asked to distinguish between benign and malignant thyroid nodules because it is necessary to be aware of the difference when creating treatment plans and surgical strategies,or when performing conservative monitoring of treatment.Examinations of suspected nodules in the clinic are performed using ultrasound,computed tomography(CT),magnetic resonance imaging(MRI),and positron emission tomography(PET).New iterations of the aforementioned imaging techniques have also been integrated into clinical practice including ultrasound contrast,and perfusion or enhanced CT,The use of 18F-FDG in diffusion-weighted imaging(DWI)and PET/CT has been proposed as a useful tool for the distinguishing benign from malignant thyroid nodules.However,all these techniques are hampered by a number of limitations.For example,ultrasound has insufficient power for retrostermal goiters.Fine needle aspiration biopsy(FNAB)is highly sensitive and specific,and it is commonly used to identify benign and malignant thyroid nodules.However,it is an invasive test that can cause physical discomfort or pain for patients,with a 10%-15%rate of non-definitive diagnosis,And fine needle biopsy is not recommended for simple cysts,unless it is aspiration to relieve symptoms.CT uses radiation and is not suitable for pregnant women or adolescents.18FDG-PET uptake in thyroid nodules confirmed by ultrasonography increases the risk of thyroid cancer.Contrast-enhanced MRI is forbidden for patients with renal failure and contrast media allergy.Therefore,a noninvasive and economical method is urgently needed in the clinic to detect and discern between benign and malignant thyroid nodules.Amide proton transfer(APT)imaging is a molecular MRI method based on chemical exchange saturation transfer that can be used to detect endogenous mobile proteins and peptides even at relatively low molecular concentrations.Protein accounts for approximately 18%of the human body weight and performs most cellular functions.These proteins can be divided into two types:semi-solid proteins and mobile proteins.Mobile proteins are the basis of APT imaging.APT imaging has been introduced in the clinic for the imaging of breast cancer,brain tumors,rectal cancer,lung cancer,prostate cancer,and non-neoplastic diseases,such as stroke and ventral hernia.Previous studies have shown that APT imaging,as an MRI biomarker for malignant tumors,can help identify the most active proliferative components in the tumor and predict the response of the tumor to treatment.Although APT imaging has had a positive effect on the diagnosis of diseases,to date,APT images have not been developed for or applied to thyroid nodules.DWI obtains image contrast by measuring the degree of freedom and diffusion direction of water molecules in tissue.The apparent diffusion coefficient(ADC)is an important parameter of DWI images,which are commonly used in the diagnosis of the thyroid gland.Zonally oblique multi-slice(ZOOM)imaging is a novel DWI imaging method.The ZOOM acquisition method provides better image quality and accuracy than non-ZOOM technology.It has been proven that it can be applied to the diagnosis of other diseases by scanning areas of the body such as the cervical spinal cord.A shorter time of repetition(TR)can be obtained when ZOOM DWI is used,along with better image quality,higher blood contrast,and less magnetically sensitive artifacts.PurposePre-operative non-invasive differentiation of benign and malignant thyroid nodules is difficult for doctors.This study aims to determine whether amide proton transfer(APT)imaging and zonally oblique multi-slice(ZOOM)diffusion-weighted imaging(DWI)can provide increased accuracy in differentiating benign and malignant thyroid nodules.MethodsThis retrospective study was approved by the institutional review board and included 60 thyroid nodules in 50 patients.All of the nodules were classified as malignant(n = 21)or benign(n = 39)based on pathology.It was meaningful to analyze the APT and apparent diffusion coefficient(ADC)values of the two groups by independent t-test to identify the benign and malignant thyroid nodules.The relationship between APT and ZOOM DWI was explored through Pearson correlation analysis.The diagnostic efficacy of APT and ZOOM DWI in determining if thyroid nodules were benign or malignant was compared using receiver operating characteristic(ROC)curve analysis.ResultsThe mean APTw value of the benign nodules was 2.99±0.79,while that of the malignant nodules was 2.14±0.73.Additionally,there was a significant difference in the APTw values of the two groups(P<0.05).The mean ADC value of the benign nodules was 1.84±0.41,and was significantly different from that of the malignant nodules,which was 1.21±0.19(P<0.05).Scatter point and Pearson test showed a moderate positive correlation between the APT and ADC values(P<0.05).The ROC curve showed that the area under the curve(AUC)value of ZOOM DWI(AUC=0.937)was greater than that of APT(AUC=0.783)(P=0.028).ConclusionAPT and ZOOM DWI imaging improved the accuracy of distinguishing between benign and malignant thyroid nodules.ZOOM DWI is superior to APT imaging(Z=2.198,P<0.05).