4DTHYROID® and Thyroid Malignancy
Detecting Tomorrow’s Cancer Today
4DTHYROID® is a diagnostic service that can lead to early detection of malignant thyroid lesions. The incidence of thyroid malignancy is increasing. The most common benefit derived from the use of 3-dimensional (3D) and 4-dimensional (4D) ultrasound rather than 2-dimensional (2D) ultrasound is an improved ability to visualize complex 3D structures. 3D and 4D ultrasound is being used in obstetrics, gynecology, orthopedics, internal medicine, emergency medicine, cardiology, and many other fields of medicine. Potential clinical use for 4D ultrasound technology for thyroid gland would include Fine Needle Aspiration Biopsy (FNAB) of thyroid nodule with more accurate needle placement, Volume measurement with 3D and 4D ultrasound.
This use of technology has been discussed in most recent thyroid nodule management guideline by American Association of Clinical Endocrinologists (AACE). Currently available, 2D ultrasound technology has improved the accuracy of FNAB and has reduced the false negative FNAB rate to about five percent. The most common cause of a false negative cytology diagnosis is sampling error. Visual misperception with current 2D technology may be one cause of this clinical problem. The key to ultrasound- guided biopsy is continuous visualization of the needle tip, not only during needle placement but also during tissue acquisition. Without accurate identification of the needle tip, damage to collateral structures such as vessels, nerves or vital organ may occur.
When the 2D ultrasound is used for needle visualization, the planar nature of the 2D ultrasound images may limit the needle visualization during insertion. If the needle is directed out of the image plane, the examiner often loses sight of the needle track. More advanced 3D and 4D ultrasound machines have improved image resolution as compared to 2D ultrasound devices. High-resolution ultrasound is the most sensitive test available to detect thyroid lesions, measure their dimensions, identify their structure, and evaluate diffuse changes in the thyroid gland.
Conventional 2D ultrasound images are reconstructed into 3D images by the operator’s brain. The latest real-time 3D or 4D equipment acquires and constructs the volumetric dataset instantaneously, allowing for coronal, sagittal, and lateral scanning, as well as oblique planes to see anatomic relationships with rotating planes. It is important to understand that 3D ultrasound is a dataset that contains a large number of 2D planes (B-mode images).
For example, if a book on a shelf is one 2D plane, then all the books on the shelf is the entire dataset. Once the volume is acquired using a dedicated 3D probe you can “walk” through the volume in a manner similar to looking at all the books on a shelf, meaning you can walk through the various 2D planes that make up the entire volume. 4D ultrasound technology is currently the only technology that can perform 3D volume measurement of benign and malignant thyroid lesion. 3D ultrasound is a static display of the various reformatting techniques based on the acquisition of a static volume; 4D ultrasound displays a continuously updated and newly acquired volume in any rendering modality creating the impression of a moving structure. Real-time capacity is not generally available with all 3D ultrasound machines.
4D ultrasound can provide highly accurate localization of benign and malignant lesions in the thyroid gland and delineate their margins from surrounding tissue and show their proximity to the thyroid capsule and potential capsular invasion. This can be very useful for thyroid surgeon in preoperative risk assessment and cancer staging prior to thyroid surgery. With this technology, we have been able to assess capsular invasion and extra-thyroidal extension of thyroid malignancy into the surrounding tissue and anatomic structures like esophagus, trachea and muscles near the thyroid gland. This technique can provide a better assessment about the extent of lymph node resection and potential complications related to surgery. Thyroid surgeons may be able to inform their patients preoperatively more accurately about possible complications related to surgery.
Figure 1 – 3D volume measurement.
Figure 2 – 3D image of malignant thyroid lesion with irregular surface.
The 3D volume measurement with 4D ultrasound is an additional component of thyroid nodule examination with 4DTHYROID®. It is a powerful tool in quantifying the size of thyroid nodule and lymph nodes near the thyroid gland. It can provide accurate direct measurements of volume, and direct visualization of margins for benign and malignant thyroid nodules. This new technology using 3D volume measurement can be done with one single volume number or measurement instead of current methods of measurement technique (longitudinal x transverse x width). The accuracy of current 2D measurement technique is limited particularly for the lesions with irregular margins or shape.
4DTHYROID® technology may be a useful tool in diagnosing parathyroid adenoma including intra-thyroidal parathyroid adenoma. Localization of a parathyroid adenoma in patients with multi-nodular goiter can be challenging, particularly when the parathyroid adenomas are attached to the thyroid gland. In those instances, the current 2D ultrasound cannot demonstrate with certainty if the parathyroid adenoma is inside or outside of the thyroid gland. The coronal view can show definitively the intra or extra-thyroidal location of the parathyroid adenoma. Real-time capacity is not generally available with all 3D ultrasound machines.
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