US GUIDED RF ABLATION

OF THYROID NODULES

Prof. Dr. Cem Yücel

GAZI UNIVERSITY SCHOOL OF MEDICINE

DEPARTMENT OF RADIOLOGY

THYROID NODULES

• Nodule incidence: – Palpation: 4-8 %

– Ultrasound: 10-41 %

– Autopsy: 50 %

• Malignity rate: ≈ 10 %

• Indications for therapy in benign nodules: – Compression symptomes

• Pain, disphagia, coughing, feeling of foreign material)

– Cosmetic

– Autonomously functioning nodules

STANDARD TREATMENT

• Malignant:

– Surgery

– Recurrent tumors:

Surgery is challenging, comp. rate ↑

• Benign:

– Levothyroxine supression?

– Surgery

INDICATIONS FOR RF ABLATION

• Benign symptomatic cold nodules

• Autonomously functioning nodules

• Well-differentiated malignant tumor recurrences

PRE-PROCEDURAL EVALUATIONS

• US evaluation: – Properties of the nodule(localization, neighboring

structures, size, echogenicity, presence of calcification, ratio of solid component, internal vascularity)

– Nodules with malignant characteristics are excluded

– Determination of nodule volume

• Biopsy: – Malignity should be excluded by at least two

seperate FNAB’s or one core biopsy

PRE-PROCEDURAL EVALUATIONS

• Laboratory tests

– Complete blood count

– Coagulation parameters

– Levels of thyroid hormones, auto-antibodies,

calcitonin, T3, T4, TSH,

PRE-PROCEDURAL EVALUATIONS

• Informed consent – Size of ablated nodules decrease in months.

– More than one sessions may be necessary.

– Treated nodule or other nodules may regrow and

additional treatment may be required.

– Patient may feel various degrees of pain during the

procedure.

– Complications.

RF GENERATOR

• Generator: RF power between 0-200 W

– During thyroid ablation 20-50 W (max 100 W)

– Impedence

RF ELECTRODE

• Electrode:

– Straight, internally cooled

– 19 gauge, length 7 cm, active tip: 0.5, 0.7, 1.0, 1.5 cm

PROCEDURE

• Patient in supine position, mild neck extension

• Local anesthesia

• Approach:

– Trans-isthmic

Entire length of the electrode can be visualized

Minimal exposure of heat to danger triangle

Electode passes sufficient amount of thyroid

parenchyma(to avoid any change of needle position and

leakage of hot ablated fluid outside the thyroid)

– Craniocaudal

– Lateral

PROCEDURE • “Moving-shot” technique (Baek et al.)

– As thyroid nodules are ellipsoid in shape, prolonged

fixation of the electrode is dangerous to surrounding

critical structures

– Initially, the electrode is positioned at the peripheral

deepest portion of the nodule

– When an echogenic area appears at the targeted area

and impedence increases, RF power ic decreased and

the electrode tip is moved back to an untreated area.

– In cystic nodules, all fluid is aspirated before ablation.

– When all nodule is ablated and transient hiperechoic

areas are observed all through the nodule, procedure

is terminated.

FOLLOW-UP

• US follow-up:

– At 1, 3, 6 and 12. months

– Volume decrease:

1. month 33-58 %, 6. month 85 %

– Echogenicity: ↓ than before ablation

– İntranodular vascularity (-)

• TSH, T3, T4

• Resolving of complaints

RESULTS

Baek JH et al. Korean J Radiol. 2011 Sep-Oct;12(5):525-40

COMPLICATIONS

Baek JH et al, Radiology. 2012 Jan;262(1):335-42

OUR EXPERIENCE

• 13 cases, 20 nodules(11F, 2 M)(Age range=33-72, med. 48)

• 10 euthyroid, 4 with hyperthyroidism

• Nodule volume = 0.6-50 cc, medium 8 cc

• Follow-up:

– 1. month(11 cases, 18 nodules): 10-83 %↓(med. 48 %)

– 3. month(5 case, 7 nodule): 34-90 %↓(med. 61 %)

– 6. month(1 case): 89 %↓

– In all cases hormone levels returned to normal

– In 1 case transient hoarseness

50 y, F, Euthyroid

Pre-ablation: Volume=16 cc

Post-RF 1. month: Volume=4.5 cc (72 %)

Post-RF 6. month: Volume=1.7 cc (89 %)

42 y, M, Hyperactive

Pre-ablation: Volume=6 cc

POST-RF 3. MONTH

Volume = 1.5 cc ( 75 % )

38 y, F, Euthyroid

Pre-ablation: Volume=3.3 cc

Per-RF Post-RF

1. MONTH 3. MONTH

1.4 cc ( 58 % ) 0.7 cc ( 79 % )

In the management of benign thyroid

nodules, RF ablation is an effective and

safe alternative to surgery in experienced

hands