The TI-RADS (Thyroid Imaging Reporting & Data System) risk categories are what the doctors are using to decide what the follow-up to the ultrasound is. Not all hospitals use the TI-RADS system, but it gives them certain criteria to decide whether to do a fine needle biopsy on any of the nodules or to follow-up with another ultrasound at a set interval in the future. So the top of the report is just a list of the different categories, and if you were to have a nodule that fits one of the criteria for biopsy, then they would recommend a biopsy. FNA = fine needle aspiration, for a thyroid nodule biopsy they use a thin needle to pull out some thyroid cells.
INDICATION: Iodine-deficiency related diffuse (endemic) goiter. This indicates your thyroid is enlarged (goiter = enlarged thyroid). I'm not sure how they know it is caused by iodine-deficiency and not an autoimmune disease, unless this is from your medical history or other tests that indicate iodine deficiency. In the US and most western nations, goiters are most often caused by Hashimoto's or Graves disease, which are autoimmune diseases where the immune system attacks the thyroid. In some cases goiters may be caused by iodine deficiency, this tends to be rare in the US since iodized salt is abundantly used, but I don't think you can rule out autoimmune disease just by ultrasound. (Maybe you can, I'm not a medical professional.)
The isthmus measures 3 mm.
The right lobe measures 6.2 cm in sagittal dimension. 6 x 3 x 8 mm
hyperechoic structure along the inferior pole of the right thyroid,
indeterminate, possibly small lymph node. Along the right level 3 nodal
station, there is a morphologically normal-appearing lymph node
measuring up to 4 mm in short axis.
The left lobe measures 5.8 cm in sagittal dimension.
Normally a thyroid ultrasound would give you three dimensions for the left and right lobes each, but here they give the longest dimension as 6.2 cm for right lobe and 5.8 cm for the left. In adults, normal size would be 4-6cm in the longest length (and 1.3-1.8 cm in thickness, thickness was not included in this report). Based on the 6.2 and 5.8 cm, it is at the top range of normal, but it is possible it is thicker.
In this category, they mention two things they found on the ultrasound, possibly lymph nodes. Indeterminate might mean they think it is either a lymph node or a small thyroid nodule. We have lots of lymph nodes in the central compartment of the neck near the thyroid, so I wouldn't be too concerned that they saw two on the ultrasound.
Estimated number of nodules > 1 cm: 0
Number of spongiform nodules > 2 cm not described (TR1): 0
Number of mixed cystic and solid nodules > 1.5 cm not described (TR2): 0
This is the list of the nodules they found... none meet criteria for FNA or fine needle biopsy. Most thyroid nodules are benign (90-95%). Some have certain features (shape, size, echogenicity - for example hypoechoic, internal vascularity, calcifications) which make the more likely to be cancer. If any of your nodules met that criteria and were larger, they might recommend a biopsy. Having risk factors does not mean that it is cancer though, just that there is more reason to verify that the nodule is benign by taking a biopsy. None of your nodules were big enough to meet the criteria for a biopsy.
For each of the nodules, they give a TI-RADS Category, which for you varies from 1 to 4. Based on size and TI-RADS score, the nodule they are most concerned about is Nodule 3.
Size: 10 x 5 x 9 mm. Location: Right mid to lower pole
Composition: Solid/almost completely solid (2)
Echogenicity: Hypoechoic (2)
Shape: wider-than-tall (0)
Margin: smooth margins (0)
Echogenic Foci: None (0)
Change in size: Baseline
TI-RADS Category: 4
This is the largest nodule noted, at 1 cm (10 mm) in diameter, and it is hypoechoic, which puts it in a higher risk category. Hypoechoic means it appears darker on the the ultrasound compared to surrounding thyroid tissue. Since it is below 1.5 cm, they do not recommend doing a FNA/biopsy on it, but to monitor it with another thyroid ultrasound in a year. If it were 9 mm and not 10mm, I don't think they would even recommend a follow-up ultrasound, based on their TI-RADS criteria.
TR4: FNA if > 1.5 cm, follow-up if 1-1.4 cm in 1, 2, 3 and 5 years
I would not worry about the other thyroid nodules at this point, no matter what the TI-RADS score, they are all about a half centimeter or smaller and even with higher risk factors, small nodules are less likely to be cancer and usually not biopsied.
General conclusions - they are recommending a follow-up ultrasound in a year to monitor the thyroid nodules, specifically nodule 3 since it is hypoechoic and larger in size (1 cm), to see if it changes in size. They will recommend doing a biopsy on it if it gets to 1.5cm.
Hope this helps. Thyroid nodules tend to be very slow growing, and your nodules are pretty small right now. They could stay this size for a long period of time, or, they may change in size, but this is usually a very slow process, and rather than do unnecessary invasive biopsies, they can monitor it for changes by ultrasound.
If your goiter is caused by iodine deficiency, your doctor should discuss this with you. If it is caused by an autoimmune disease, the treatment will be different than for iodine deficiency, so I wouldn't recommend trying to treat it yourself without discussion with your doctor. If there is something causing the goiter (hypothyroidism, caused by either iodine deficiency or another cause), then hopefully your doctor has tested your thyroid hormones (TSH, freeT3 and freeT4), as well as discussed whether you currently are experiencing any hypothyroidism symptoms. If left untreated, hypothyroidism can encourage a goiter to grow - TSH stands for thyroid stimulating hormone, and encourages thyroid growth.
Please let me know if you have any more questions, some of the terminology used in ultrasounds can be confusing and I tried to sum up the info as much as possible but I may have missed something you are concerned about.