The Thyroid Ultrasound - Making sense of it all...
The most important step after the diagnosis of a thyroid nodule is the actual thyroid ultrasound. It is the first time you have reproducible data on the nodule. You now have a starting point and also a reference point moving forward if it is one of the 80-85% of nodules that are benign. This step, however, is another step which contains pitfalls and also communication points that can make it very difficult for the patient to know if they are in trouble or not. The more one knows, the better able they are to avoid acting on misinformation. The following should serve as a guide to help make sense of the information that shows up on the Thyroid Ultrasound report. These are the questions that matter.
Was it a Thyroid Ultrasound?
First things first. Oftentimes the thyroid nodule is found incidentally on an ultrasound of the carotid arteries. The purpose of this study isn't the thyroid, so while an ultrasound technician should note and report on one if seen, their focus is on performing other measuring tasks. The thyroid happens to be adjacent to the carotid arteries, so it should be almost impossible to miss, but a technician could be blinded by the study at hand and miss it, so it is always best to have a proper Thyroid Ultrasound whether or not there is a size measurement on the other report. In this way, you are giving the technician the necessary time to accomplish the appropriate pictures and visualization and not rushing them with two tests in one. The results, hopefully, will include more information when performed as the actual thyroid study itself.
Who performed the Thyroid Ultrasound?
Most ultrasounds are performed by an ultrasound technician, who takes pictures that are provided to the Radiologist who will write and sign report. Unfortunately, there are ultrasound technicians of all skill levels who are performing this test. Some are new; some are experienced; some are having a bad day; some are in a rush for their smoke break; some care for the patient like they are their doctor; some are just collecting a paycheck. The moral of the story is, you don't know the quality of the technician you are going to get. While Thyroid Ultrasound is a skill set that they should be relatively sufficient in (because of how common it is), there is a level of experience and interpretation that is often required to get the right interpretation. Worse off, the pictures they take are then interpreted by a Physician who never got to see "all" of the live data that is coming off the ultrasound probe during the entire procedure. They only see the pictures provided. And those pictures can represent or misrepresent what is going on. Sometimes one moment may show what appears to be a well defined nodule, but then sliding a tiny bit lower and the borders and appearance are completely gone. The pictures are supporting the impression that the technician has. If they believe they see a nodule, they will take the best picture that supports that and not present pictures that make it look "iffy". While the ultrasound seems like it is cold, hard, data... the level of interpretation means it can sometimes be wrong or misleading. Therefore, "who" performs the ultrasound is an important part of the data collection. As an experienced thyroid surgeon and ultrasonographer, I have ended up dismissing dozens of patients who were scheduled for a fine needle biopsy of a thyroid nodule, that when I put the probe to the neck wasn't really there. This is only one example of the many errors that can arise with the way most radiology sites operate. The other main error I have seen over the years is what I call "carryover error". Since different technicians tend to do the studies year to year for a patient, the first thing they are expected to do is check the last ultrasound. If they send the patient home and say there were no nodules present, and the Radiologist reviews last year's study which has multiple nodules, there is going to be a problem. Therefore, the technician performing the study has a bias to find the same nodules that were present on the prior study. What happens if they don't see it the same way as the last technician or there is a major change in their interpretation. Well, this is when a nodule that isn't a nodule, can be propagated for years. I have actually disagreed with the interpretation of a Thyroid Ultrasound and sent patients for a repeat at a completely different, third-party facility. Know what the results were? Sometimes completely the opposite and different in a totally new way than the original report. Thyroid glands can look funny and require an experienced ultrasonographer to make sense of them sometimes. It is my preference that a experienced doctor should be performing the sonogram, whether it be an Endocrinologist, Radiologist, or Otolaryngologist (one might say I am biased because I am an Otolaryngologist, but in this case I don't think so).
What's written in the Report?
The next most common problem that I have seen, is with the report. Since there isn't a definitive requirement for how these reports are generated there is the problem of what is documented or not documented in the Report. As a surgeon performing Ultrasound studies, I look for the details and risk factors on Ultrasound that could affect whether having surgery is necessary. These risk factors are present to the eyes of the person performing the exam, but unless proper time is taken to get pictures that document these facts, they can get lost in the process. And it isn't only subtle ultrasound features that can be missed, I have even seen a report that barely even measured one of the multiple nodules. So you have to pay attention to what is written, but also what isn't written. When a feature isn't present, the only way to know for sure is to see a statement noting that the feature was absent. The lack of any documentation of this feature, does not support its absence. This includes features such as blood flow and microcalcifications which will be described further below. Also realize, that mentioning there are calcifications without giving the specifics of the type of calcification seen can completely change the interpretation. What gets written down, becomes really important if you don't have the opportunity to have your eyes on the screen and the ultrasound probe in your hand.
What's the worry?
The way a report is written can generate concern for the doctor and/or patient reading it, but the details matter. As a layperson, the medical wording even when normal can sound intimidating. Understanding what the surgeon should be looking for and what it means can help one make an informed decision. There are a variety of features that should be mentioned to help determine the level of risk for a nodule being Thyroid Cancer. These should be well documented on a Thyroid Ultrasound to help communicate to other physicians who are caring for the patient deliver the appropriate treatment options. The size, shape, consistency (what is called echogenecity) and makeup, blood flow, as well as presence or absence of other suspicious risk factors should all be noted.
- Size: Bigger obviously isn't better in thyroid nodules. Nodules under 1 centimeter (cm) aren't usually biopsied unless there are suspicious characteristics. Nodules 1-2cm are considered small; 2-3cm are medium size; and over 4cm are considered large. Larger nodules while possibly benign after workup are more concerning for their possible mass effects which can cause pressure and swallowing issues. When extremely large, they can compress the airway. For this reason, treatment of larger nodules is considered even when benign. Nodules under 4cm are rarely responsible for any of these symptoms. When followed over time, change in size becomes important. Thyroid nodules are generally slow growing (even cancers), so big jumps in size should be noted. Rapid increase in size is considered suspicious. If the nodule is mostly cystic or purely cystic, this change in size needs to be assessed if it is all fluid or actual mass. An increase in fluid is less concerning than that of an increase in the mass of thyroid cells of the nodule.
- Shape: The shape of the nodule and clarity of borders should be noted including if it is round or oblong, with wording of taller than wide being a suspicious factor. The borders should be clear and well defined. Ill-defined borders, irregular margins, or notation of extrathyroidal extension are also risk factors.
- Character/consistency: The character and consistency of the nodule should be noted. This includes first whether it is purely solid, purely cystic or a mixture of both often times described as a complex nodule. Cystic nodules are generally lower risk as they are made up of fluid and not cells like a solid nodule. Cystic nodules can, however, sometimes have a solid component inside. This is the portion that should be biopsied if you have one like this. Next up is the actual ultrasound signal of the nodule, noted as what is called echogenicity. A nodule will be described as hypoechoic (low echogenicity), hyperechoic (high echogenicity) or isoechoic (medium echogenicity). In general, hypoechoic nodules are considered higher risk, but a nodule can have any characteristic and still turn out to be malignant.
- Vascularity: The nodules blood flow can be assessed by use of doppler mode on ultrasound. Nodules should be checked for vascularity, with peripheral vascularity being less suspicious than central vascularity. This is indeed another subjective variable that I have seen regarded as worse or better than it really is. The eye is seen from the view of the technician performing the ultrasound. Increased central vascularity is seen as a risk factor for thyroid nodules.
- Calcifications: The most prominent of written factors is whether the nodule has calcifications or not. That being said, there are differing types of calcifications that should be interpreted differently. The three types are rim calcifications, macrocalcifications and microcalcifications. The rim calcifications are sometimes called eggshell calcifications and are not normal but not specifically a suspicious feature. They do however sometimes pose a problem for needle aspiration, as a needle does not easily penetrate an eggshell. An experienced Interventional Thyroidologist, should be able to make efforts needed to obtain a good biopsy despite these findings, although sometimes it can result in an insufficient specimen despite heroic efforts. Macrocalcifications are large calcifications which should be specified to distinguish from the suspicous finding of microcalcifications. These are also sometimes noted as "punctate" or "speckled" calcifications and are a suspicious factor. It becomes important if the report just states calcifications, that the actual type/description is noted to help decide if this is a suspicious feature or not. Important here to mention, that sometimes microcalcifications are mistakenly reported. There are benign features of a thyroid nodules that sometimes can look a little bit like them, so sometimes the calcification is in the eye of the beholder.
The most up to date information is found in the American Thyroid Association Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer. As of today, the last revision to these guidelines were published in 2015, and a new update is expected soon. It often takes a while before the general community is following these guidelines once new ones are published so checking to see if there are any updates isn't a bad idea. The general trend has been towards less aggressive treatment, and if this trend continues there may be significant updates in the near future that change surgical recommendations. The following ultrasound chart is from the 2015 ATA Guidelines and describes the above factors in a graphic form:
What now?
After the ultrasound is done, if appropriate to figure out what is next step you need to take the ultrasound, the clinical history, and the biopsy results together to formulate a reasonable decision. Your doctor should hopefully explain this through to you with the accompanying treatment options. If you want to better understand the biopsy results, please see my post on "The Most Confusing Thyroid Nodule" to clarify what the Fine Needle Aspiration results mean. After putting this all together, surgical options may be discussed. This includes partial or total thyroidectomy, as well as newer less invasive options such as Radiofrequency of the Thyroid Nodule. See the post "Avoiding Unnecessary Thyroid Surgery" to make sure that you are making a truly informed decision.
Conclusions
A Thyroid Ultrasound opens up a plethora of possibilities. There are many combinations of findings that all need to be processed together to help understand and define someone's risk of thyroid cancer. In general, one single risk factor on ultrasound is not the end of the world. The more that are present, the higher the actual risk of a nodule being cancerous. If you understand what is going on you won't let anxiety and miscommunication drive you into a bad place of worry. Remember, that in general, Thyroid Cancer remains one of the most treatable cancers out there and is not like most other cancers people talk about. Knowledge is power!
If this has helped you or if you have been through tremendous stress because of your ultrasound results, comment below.
