KHANH MAI VO, HUNG THIEN NGUYENMEDIC MEDICAL CENTER, HCMC,

VIET NAM

To evaluate the VTQ (Virtual Touch Tissue Quantification) of normal thyroid tissue and thyroid nodules.

To assess the characteristics of VTI (Virtual Touch Tissue Imaging) of thyroid nodules.

To assess the ability of VTQ and VTI in differentiating between benign and malignant thyroid nodules.

A cross-sectional studyOne hundred and thirty nodules underwent

conventional ultrasound, including Color Doppler ultrasound using a 7.5MHz linear transducer.

Nodule stiffness was measured and assessed by VTQ and VTI of ARFI-Imaging (Acuson Siemens S2000).

FNAC (Fine needle aspiration cytology) under ultrasound guide was used as reference method.

PATIENT CHARACTERISTICS:

Mean age: 45 (range 16 – 69)

Mean size of nodule: 14mm (range 5 – 47mm)

Table 1: ARFI velocity characteristics:

ARFI velocity (m/s)

Normal thyroid tissue

Benign nodule Malignant nodule

Mean standard deviation

1.51 0.07 2.15 0.09 3.21 0.46

Median 1.41 2.11 2.59

Minimum 0.84 0.80 0.90

Maximum 3.00 4.04 9.22

Figure 2: Classification convention of VTI (from left to right, from top to bottom): dark = 1, iso = 2, bright =3, mixed color = 4.

Table 2: Frequency table and Chi-square test for independence of VTI and the differentiation of benign and malignant nodules:

Codes X

Codes Y 1 2 3 4

0 30 10 89 70 199 (76.5%)

1 51 1 4 5 61 (23.5%)

81 (31.0%)

11 (4.2%)

93 (35.7%)

75 (29.1%)

260

Chi-square

102.553

AUROC was 0.731, VTQ of ARFI-Imaging could be considered as a helpful method in differentiating of benign and malignant thyroid nodules.

At the cut-off of 2.16m/s, the sensibility and specificity in differentiation of benign and malignant thyroid nodules were 79.4% and 53.7%.

The darker VTI was, the more malignant thyroid nodule was.

The Chi-square test result showed a dependence between VTI and the differentiation of benign and malignant nodules, alpha level of significance = 0.001.

ARFI can be performed in thyroid nodule with reliable results.

The combination of VTQ and VTI can give a better differential diagnosis.

Larger studies are awaited.

Andy Milkowski: Elasticity reaching Clinical Maturity, Siemens.

Mark L.Palmeri – Kathryn R. Nightingale: Acoustic Radiation Force-Based Elasticity Imaging Methods, Interface Focus (2011).

Sporea I, Vlad M, Bota S, Sirli RL, Popescu A, Danila M, Sendroiu M, Zosin I: Thyroid stiffness assessment by acoustic radiation force impulse elastography (ARFI).

Figure 3: VTQ = 5.35m/s of a PTC (papillary thyroid carcinoma) nodule.

Figure 4: VTI of the same patient showed a dark color nodule.

Figure 5: VTQ = 1.88m/s of a benign nodule.

Figure 6: VTI of the same nodule showed a bright color

structure.