RADIOLOGICAL REPORT

1. Review PREVIOUS STUDIES.

2. Description of the THYROID GLAND:

•DIMENSIONS of the two thyroid lobes (AP, T, and CC) and AP diameter of the isthmus.

•Description of the GLANDULAR PARENCHYMA (echogenicity, vascularization).

• Normal ECHOGENICITY is homogeneous and greater than neck muscles. In subacute/chronic thyroiditis we can find hypoechoic and poorly defined areas.
  

  Fig 1: Pseudonodular and hypoechoic area, and geographic borders measuring 6 x 12 mm, suggestive of an area of ​​focal thyroiditis.
• VASCULARIZATION: can be altered in thyroiditis.
  

  Fig 2: The thyroid gland shows heterogeneity of its echostructure with increased vascularization, due to thyroiditis.

3. Evaluate the LATEROCERVICAL lymph node CHAINS.

4. Description of the THYROID NODULES and other pathology

1. Nodules smaller than 5mm should NOT be described. If greater than 5mm, images of the 3 dimensions should be taken in the sagittal and transverse planes.
2. If there are multiple nodules, the radiologist should identify the 4 most suspicious nodules and describe them to facilitate follow-up in subsequent studies.
3. Growth will be defined as: an increase in diameter of 20% or 2mm in two dimensions or an increase in volume of 50%
4. If the TI-RADS category increases but does not meet the FNA criteria due to its dimensions, annual follow-up should be done.

IMAGING TECHNIQUES

ULTRASOUND

•Gold Standard.

•Its main role is to exclude nodules suspicious of thyroid cancer (7-15% of the detected nodules)

•It is performed with a high-frequency linear transducer (7Hz) and with the neck in hyperextension.

•LIMITATIONS:

•Inter-operator variability.

CEUS

Analyzes patterns of macro and microvascularization. Thanks to the incorporation of the latest generation contrasts, its applicability in thyroid pathology has increased. It detects malignant nodules with a sensitivity of 85% and a specificity of 82%.

•Classifications are currently being created, such as CEUS-TI-RADS. Some factors that are considered malignant according to CEUS-TI-RADS are: 

• Centripetal/centrifugal enhancement
• Absence of ring enhancement
• Hypo-hyperenhancement

ELASTOGRAPHY

•Elastography in combination with B-mode ultrasound increases sensitivity and specificity in the characterization of thyroid nodules 

•When compressed, pathological lesions are more rigid than the adjacent healthy tissue.

•LIMITATIONS:

•Those cancers with stroma similar to normal tissue, such as follicular cancer, will not be detected. 

•It also does not give us information on nodules of a cystic nature or those with calcifications. 

GAMMAGRAPHY

•It analyzes the uptake of a radioactive iodine marker (18F-FDG) by the thyroid. It is not recommended for the evaluation of previously diagnosed thyroid nodules, since thyroid uptake can be detected incidentally in up to 1-2% of patients. 

•Uptake increases the risk of malignancy of the nodule, and clinical evaluation and FNA are recommended for nodules ≥1 cm that present high uptake.

•Nodules less than 1 cm, which do not meet the criteria for FNA, should be periodically reviewed by ultrasound. 

ACR TI-RADS

The TI-RADS system was designed to reduce the number of biopsies of benign thyroid nodules and increase diagnostic accuracy. It evaluates 5 categories.

1. COMPOSITION
2. ECHOGENICITY
3. SHAPE
4. MARGINS
5. PRESENCE OF CALCIFICATIONS

•A score is selected for each of these categories, according to the characteristics of the nodule.

•The total score obtained classifies the nodules into 5 types, from TI-RADS 1 (benign) to TI-RADS 5 (high suspicion of malignancy).

Fig 15: TI RADS classification

•From TI-RADS 3 onwards, FNA may be indicated. 

Fig 16: Recommendations on when to perform a PAAF

EXAMPLES

TI RADS 2

Fig 3: TI RADS 2. Mixed nodule predominantly cystic.

Fig 4: TI RADS 2. Spongiform nodule.

TI RADS 3

Fig 5: TI-RADS 3. At the junction of the isthmus-LTD, a solid (2 points) and isoechogenic (1 point) nodule is identified, with oval morphology and well-defined contours, with diameters of 6 x 11 x 12 mm.

Fig 6: Ti-RADS 3. Well-defined hyperechoic (1 point), solid nodule (2 points) measuring 0.4 x 0.3cm and thin hypoechoic halo.

Fig 7: TI- RADS 3. TI-RADS 3. Mixed nodule (1 point), predominantly cystic with echoes floating inside, identifying a central non-vascularized, slightly hypoechoic solid area (2 points), suggestive of a cyst complicated by bleeding with possible clots inside.

TI RADS 4

Fig 8: TI-RADS 4. Hypoechoic (2 points) well-circumscribed solid nodule (2 points) measuring 1.75 x 1.78 cm.

Fig 9: TI-RADS 4. Solid (2 points) and hypoechoic (2 points) nodule measuring 3.4 cm x 3.3 cm x 5 cm, with small cystic areas in its thickness. It presents central and peripheral calcifications (2 points).

Fig 10: TI RADS 4. Nodule located in the isthmus, mixed with predominantly solid (1 point), isoechoic (1 point) and wider than high, currently presents a small partial peripheral calcification (2 points).

TI RADS 5 

Fig 11: TI RADS 5. Solid nodule (2 points) hypoechoic (2 points), with microcalcifications (3 points), measures 2.02 x 1.24 cm.

Fig 12: Ti-RADS 5. Hypoechoic (2 points) Solid nodule (2 points) taller than it is wide (3 points), which measures 1 x 0.8 cm.

Fig 13: TI-RADS 5. Solid nodule (2 points), hypoechoic (2 points), oval morphology, taller than it is wide (3 points), with signs of extracapsular invasion and contact with the right common carotid (3 points)

FNA

•It is the technique with more scientific evidence. It has a sensitivity of 65-98% and a specificity of 72-100% to detect thyroid cancer.

•LIMITATIONS:

It depends on the quality of the sample. It is indeterminate or non-diagnostic in 15-20% of patients. In these patients, the FNA is repeated; and if it remains indeterminate and malignancy is suspected, a thyroidectomy will be performed.

•Some characteristics related to non-diagnostic punctures are:

• macrocalcifications
• size <5-10mm
• cystic predominance

It should be limited to a MAXIMUM OF TWO suspicious NODULES (those with a greater TR) or any suspicious ADENOPATHY 

•REQUIREMENTS:

• Coagulation between normal ranges.
• Informed consent.
• Material: gauze + chlorhexidine, 25 G or 22 G intramuscular needle, plastic syringe, slides.
• Posture: The patient will be placed in a supine position with a pillow underneath to facilitate hyperextension of the neck.

•PROCEDURE:

• Ultrasound will be performed to characterize the nodule and detect the adjacent vascularization, avoiding vascular structures.
• Prior asepsis with chlorhexidine.
• The needle must be parallel to the transducer leaving a separation of 1-2 cm to avoid contamination of the needle.
• Puncture of the thyroid nodule with aspiration and back-and-forth movement to obtain the maximum amount of material (for 5-10 seconds) trying to obtain a sample from the different quadrants of the nodule and the solid/suspicious areas, avoiding cystic areas and calcifications.
• Placement of the material on the slide.

•COMPLICATIONS: discomfort, hematoma, hemorrhage (due to puncture of vascular structures), vasovagal reaction… 

EXAMPLE OF AN FNA DONE ON A SUSPICIOUS ADENOPATHY

Fig 14: Subcentimetric, markedly hypoechoic adenopathy with loss of its fatty hilum, which is suspicious, was identified in the left supraclavicular chain. An ultrasound-guided FNA was performed.