Application Of Contrast-enhanced Ultrasound In Percutaneous Microwave Ablation Of Thyroid Nodules

To explore the effectiveness of contrast enhanced ultrasound (CEUS) in diagnosis, size determining, guidance and efficacy verification during percutaneous microwave ablation treatment of thyroid nodules.Between March 2012 to July 2013, there were 56 patients with 71 thyroid nodules underwent microwave ablation (MWA) in our department. Before the treatment, all the nodules were assessed by two-dimension ultrasound (2DUS) and Color Doppler Flow Imaging (CDFI). Following the contrast-enhanced ultrasound(CEUS),we observed the beginning of contrast agent enhancement and the dissipation as a whole, and analyzed the time-intensity curve (TIC) with ACQ software.The results of CEUS were contrasted with pathologic diagnosis.2DUS and CDFIfor76 patients (91 nodules) were performed immediately after the ablation to determine whether the ablation was absolute or not. Based on the CEUS, the residual areas were treated with further completely ablation by adjust the needle position.The tumor size, internal echoe, intratumoral vascularity, and contrast agent dose of all the 16 tumors were evaluated with ultrasound 1,3,6 and 12 months after treatment. Select regions of interesting in the tumor, tissue around tumor and normal glandular tissue, respectively, and analyze the time-intensity curve with ACQ software.(1) In CEUS pre-ablation, most nodular goiter cases presented as isoenhancement or hypoenhancement, hypoenhancement few; adenomas showed hyper-enhancement with a"fast-in and slowly-out"pattern; most papillary thyroid cancers showed inhomogeneous isoenhancement or hypoenhancement, and dissipated earlier than the peripheral glandular tissue. The maximum diameter of the thyroid nodules assessed with CEUS were larger than that with 2DUS.(2) Immediately after the ablation the conventional ultrasound showed the echos of all the 91 nodules have been increased to different degrees, the the sign of blood flow reduced, and uncompleted ablation was observed in 7 cases (7/91; 7.7%). While by CEUS, uncompleted ablation was observed in 15 cases (15/91,16.5%) (p<0.05). Immediately after MWA, the maximum diameter of the thyroid nodules were 2.67±3.16cm in size by 2DUS. However it was 2.33±2.67cm on the CEUS (p<0.05).(3) The numer of cases evaluated with CEUS after microwave ablation was 3,2,4, and 3 at the 1,3,6 and 12 months follow up visit respectively.Non-enhancement was showed on CEUS. Of all the 16 tumors, the volume was 1.07±2.38cm3 by 2DUS. However it was 1.00±2.22cm3 on the CEUS (p<0.05)(1)CEUS can depicte thyroid nodule vessels and tumor perfusion imaging efficiently, providing more information for diagnosis of benign and maligant thyroid masses, the pouch or solid masss and determining the tumor size, having potential applications in microwave ablation.(2)CEUS can dynamically show the thyroid nodule perfusion imaging and the different appearance of residual lesions, which will be of guiding significance to when to stop an ablation.(3)CEUS can accurately discriminate the coagulation necrosis from residual tumors after microwave ablation. The evaluation of the thyroid nodule microwave ablation curative effect and hemodynamics change has great practical value.