Elastography predicts thyroid cancer: comparison of two methods

Transcription

1 Elastography predicts thyroid cancer: comparison of two methods Poster No.: C-1267 Congress: ECR 2014 Type: Scientific Exhibit Authors: O. Sommer 1, H. Lanz 1, J. Hutter 1, M. Eberwein 2, J. Pratschke 2, G. Keywords: DOI: Wimmer 2 ; 1 Schwarzach im Pongau/AT, 2 Innsbruck/AT Thyroid / Parathyroids, Elastography, Ultrasound, Diagnostic procedure, Tissue characterisation /ecr2014/C-1267 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 13

2 Aims and objectives Palpation is an integral part in thyroid assessment. Nodule consistency is an accepted useful clinical parameter for judging its dignity. 1-5 The aim of this prospective, randomized study was (1) to evaluate nodular hardness measured with ultrasound-elastography for differentiating benign versus malignant, and (2) to compare values acquired with two different elastography techniques: compression versus shear wave. Methods and materials Patients 80 patients, scheduled for surgery because of nodular thyroid disease underwent ultrasound on two different scanners, one equipped with compression elastography (Hitachi Preirus ), one with shear wave elastography (Siemens S 2000 ). Patient data and results of previous investigations (e.g. scintigraphy and histologic results after biopsy) were blinded. Randomisation came through daily routine work in our hospital - goiter is an endemic disease in our alpine population. The study was approved by the responsible Ethics Committee of the local government. Examination technique All identified thyroid nodules were evaluated regarding size, margins, vascularity, stiffness and shear wave velocity in nodules and normal thyroid tissue. the following ultrasound techniques were applied: grey scale imaging (Fig. 1) color doppler and power doppler imaging (Fig. 2) free hand ultrasound compression (Fig. 3): repeated manual compression to the ultrasound probe leads to tissue displacement which is registered on a frame to frame basis and displayed as a color overlay on the grey scale image. Harder areas are coded in blue. 3-6 Acoustic Radiation Force Image (ARFI, Virtual Touch Image, VTI) (Fig. 4): short duration acoustic radiation forces lead to tissue displacement which Page 2 of 13

3 is registered and displayed as a gray scale map. Harder areas are coded in black. 3,6-8 Virtual Touch Quantification (VTQ). (Fig. 5) Shear wave speed is registered in a fixed size region of interest and absolute values (m/sec) are displayed. The stiffer the tissue the higher the speed. All exams were performed by one radiologist with profound experience in ultrasound of the thyroid and elastography. 3, 6-8 Statistical analysis Nodular size, margins and vascularity were categorised. Stiffness was calculated semiquantitatively with strain ratio measurements: regions of interests (ROI s) were drawn in normal thyroid tissue and the hardest zones of the respective nodule and the ratio calculated (Fig. 6). 9 Attention was paid to achieve ROI s with comparable size and distance from the skin, wherever possible. Strain ratios were measured with compression elastography and VTI for each nodule. Absolute shear wave velocity was calculated on positioning a fixed size ROI in the hardest area of the respective nodules. Calcifications, cystic as well as necrotic zones were avoided. Additionally, velocity measurements were also obtained in morphologically normal thyroid tissue in all patients where the fixed size ROI could be fitted without superpositions. Images for this section: Page 3 of 13

4 Fig. 1: Grey scale image: 1.7 cm inhomogeneous nodule in the caudal part of the left thyroid lobe with unsharp margins Fig. 2: Color doppler image: same nodule as Fig. 1. No hypervascularity noted. Page 4 of 13

5 Fig. 3: Free hand ultrasound compression elastogram: same nodule as Fig. 1. Repeated manual compression leads to tissue displacement which is registered and displayed as a color overlay on the grey scale image. Harder areas are coded in blue. A strain ratio is calculated comparing stiffness in two areas of interest. Fig. 4: Acoustic Radiation Force Image (Virtual Touch Image, VTI): same nodule as Fig. 1. Short duration acoustic radiation forces lead to tissue displacement which is registered and displayed as a gray scale map. Harder areas are coded in black. A strain ratio is calculated comparing stiffness in two areas of interest. Page 5 of 13

6 Fig. 5: Virtual Touch Quantification (VTQ): same nodule as Fig. 1. Shear wave speed is registered in a fixed size region of interest and absolute values (m/sec) are displayed. The stiffer the tissue the higher the speed. Fig. 6: Free hand compression ultrasound elastogram. 12 mm follicular carcinoma. Strain ratio 13,67. Page 6 of 13

7 Results Parameters and cut off values Due to the heterogeneity of nodules in endemic goiter and due to an expected low incidence of advanced cancer, we did not make use of the described visual scoring systems 2-4,10-15 which are based on the analysis of elastographic patterns. The latter taken into account of, however, for the positioning of ROI s for strain ratio measurements and velocity quantification. For compression elastography cut off values for strain ratios are described to be in a range of 2 to 4 - lesions depicting higher values more likely to be cancer. 3,16-19 Malignant nodules usually exhibit higher shear wave speed measured with Virtual Touch Quantification (VTQ). 20 Cut off values values discriminating between benign and malignant lesions are in the range of 2,55-2,57m/s. 3 Hou XJ, et al assign a cut off value of 2,42 m/s a sensitivity of 80% and specificity of 89,23%. 8 Results nodules and histology 123 nodules were studied in 80 patients. Overall, in 6 patients (7,5%) carcinomas were confirmed by surgery and pathology. compression elastography Strain ratio (SR) values were broadly distributed in our study population. Only 23% of nodules presented with strain ratio values of under 4. Benign nodules with a SR of up to 84 were found. Strain ratio values of malignant nodules were in the range of 2 to 145. Compression elastography clearly identified 2 carcinomas (SR 133 and 145) (Fig. 7). acoustic radiation force imaging Page 7 of 13

8 Similarily to compression elastography findings, there was a broad distribution of SR values in benign nodules, ranging from 0,6 to 7, malignant nodules showing values from 2 to 16. With shear wave elastography 1 malignant nodule was identified clearly (SR of 16) (Fig. 8). shear wave velocity No conclusive results were obtained by measuring absolute velocities (m/s; kpa) of shear waves. The range of shear wave velocity was 0.99 to 2.58 m/s in malignant nodules, in the range of values in normal thyroid tissue and benign nodules in our study population (Fig. 9). We did not experience "X.XX m/s" values as described by Okada et al 7 in malignant nodules in our study population. comparison of techniques Elastographic patterns as depicted as overlay or map on the corresponding grey scale images showed a moderate to high degree of consistency for compression elastography and VTI (ARFI). SR values calculated from these maps did not correlate well (Fig. 10) as did calculated velocities (Fig. 11). Images for this section: Fig. 7: Compression elastogram. Nodular goiter. The nodule in the lower half of the thyroid (right side on the image) displays a highly pathologic strain ratio. Histology revealed this nodule to be a papillary carcinoma. Page 8 of 13

9 Fig. 8: same patient as Fig. 7. Strain ratio by virtual touch imaging was 3,8 for the benign nodule (left side of the image) and 16 (right side of the image) for the malignant nodule in the lower half of the right thyroid lobe. Fig. 9: Virtual Touch Quantification: shear wave speed being higher in the benign (left side of the image) than in the malignant (right side of the image) nodule. Fig. 10: Compression elastogram and Virtual Touch Image (VTI) of a right sided nodule embodying a papillary microcarcinoma. Suspicious finding with the compression technique, inconspicuous VTI. Page 9 of 13

10 Fig. 11: same patient as Fig. 10. Shear wave speed is higher in normal thyroid tissue than in the malignant thyroid nodule, contradictory to the elastograms. Page 10 of 13

11 Conclusion In our study, ranges of calculated values differ considerably from literature data. This may well be due to our study population with it s high incidence of endemic goiter. The shear wave technique fares inferiorly in our study which may be related to local factors such as tissue heterogeneity. The diagnostic value of direct quantification of shear wave velocities in thyroid nodules remains questionable in our study population. This may be related to tissue properties and a broad overlap of velocity ranges in benign and malignant nodules. Not suitable as a stand-alone technique, compression elastography, however, provides valuable additional information in the established work up of thyroid nodules. Personal information References [1] Lyshchik A, Higashi T, Asato R, et al. Thyroid gland tumor diagnosis at US elastography. Radiology 2005; 237: [2] Shweel M, Mansour E. Diagnostic performance of combined elastosonography scoring and high-resolution ultrasonography for the differentiation of benign and malignant thyroid nodules. Eur J Radiol 2013; 82: [3] Cantisani V, Lodise P, Grazhdani H, et al. Ultrasound elastography in the evaluation of thyroid pathology. Current status. Eur J Radiol 2013 in press. [4] Hong Y, Liu X, Li Z, et al. Real-time ultrasound elastography in the differential diagnosis of benign and malignant thyroid nodules. J Ultrasound Med 2009; 28: [5] Ding J, Cheng H, Ning C, et al. Quantitative measurement for thyroid cancer characterization based on elastography. J Ultrasound Mes 2011; 30: [6] Balleyguier C, Canale S, Ben Hassen W, et al. Breast elasticity: principles, technique, results: An update and overview of commercially available software. EJR 2013; 82: Page 11 of 13

12 [7] Okada R, Suzuki M, Takeuchi K, et al. Measurement of shear wave velocities coupled with an evaluation of elasticity using ARFI elastography in diagnosis of papillary throid carcinoma. Open J of Clinical Diagnostics 2013; 3: [8] Hou XJ, Sun AX, Zhou XL, et al. The application of virtual touch tissue quantification (VTQ) in diagnosis of thyroid lesions: a preliminary study. Eur J Radiol 2013; 82: [9] Aydin R, Elmali M, Polat AV, et al. Comparison of muscle-to-nodule and parenchymato-nodule strain ratios in the differentiation of benign and malignant thyroid nodules: which ohe should we use? Eur J Radiol 2013 in press. [10] Rubaltelli L, Corradin S, Dorigo A, et al. Differential diagnosis of benign and malignant thyroid nodules at Elastosonography. Ultraschall in Med 2009; 30: [11] Friedrich-Rust M, Sperber A, Holzer K, et al. Real-time elastography ans contrastenhanced ultrasound for the assessment of thyroid nodules. Exp Clin Endocrinol Diabetes 2009; 118(9): [12] Razavi SA, Hadduck TA, Sadigh G, et. al. Comparative effectiveness of elastographic and B-Mode ultrasound criteria for diagnostic discrimination of thyroid nodules: a meta-analysis. AJR 2013; 200: [13] Park SH, Kim SJ, Kim EK, et al. Interobserver agreement in assessing the sonographic and elastographic features of malignant thyroid nodules. AJR 2009; 193:W416-W423. [14] Cappelli C, Pirola I, Gandossi E, et al. Real-time elastography. A useful tool for predicting malignancy in thyroid nodules with nondiagnostic cytologic findings. J Ultrasound Med 2012; 31: [15] Rago T, Santini F, Scutari M, et al. Elastography: new developments in ultrasound for predicting malignancy in thyroid nodules. J Clin End Metab 2007; 92(8): [16] Cantisani V, D Andrea V, Biancari F, et al. Prospective evaluation of multiparametric ultrasound and quantitative elastosonography in the differential diagnosis of benign and malignant thyroid nodules: preliminary experience. Eur J Radiol 2012; 81: [17] Cantisani V, Consorti F, Guerrisi A, et al. Prospective comparative evaluation of quantitative-elastosonography (Q-elastography) and contrast-enhanced ultrasound for the evaluation of thyroid nodules: preliminary experience. Eur J Radiol 2013; 82: [18] Ning CP, Jiang SQ, Zhang T, et al. The value of strain ratio in differential diagnosis of thyroid solid nodules. Eur J Radiol 2012; 81: Page 12 of 13

13 [19] Xing P, Wu L, Zhang C, et al. Differentiation of benign from malignant thyroid lesions. Calculation of the strain ratio on thyroid sonoelastography. J Ultrasound Med 2011; 30: [20] Zhang YF, Xu HX, He Y, et al. Virtual touch tissue quantification of acoustic radiation force impulse : a new ultrasound elastic imaging in the diagnosis of thyroid nodules. PLoS ONE 2012; 7(11):e49094 Page 13 of 13