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Thứ Tư, ngày 29 tháng 2 năm 2012

Elastography was not a useful tool in recommending fine-needle aspiration biopsy of thyroid nodules

2 bài sau đề cập khả năng của RTE (real-time elastography) như các máy ALOKA, HITACHI, TOSHIBA, SIEMENS Antares... khảo sát nhân giáp, có hạn chế trong tiên đoán lành ác trước sinh thiết. Lúc khám phải ấn đầu dò bằng tay để đo độ cứng nhân giáp, do đó kỹ thuật khám free-hand này lệ thuộc vào người khám. Bài sau, có bình luận và nói đến shear wave elastography [siêu âm đàn hồi sóng biến dạng], là kỹ thuật mới hơn ớ máy Supersonic Imagine, còn gọi là kỹ thuật SSI (supersonic shear imaging) hay ở máy SIEMENS ACUSON S2000, còn gọi là kỹ thuật tạo hình xung lực bức xạ âm [acoustic radiation force impulse,ARFI, imaging). Sóng biến dạng tạo ra từ đầu dò và làm dời chỗ mô để đo độ cứng tổn thương. Người khám không phải đè ấn nên kỹ thuật không lệ thuộc người khám và có tính lập lại cao. Dòng máy này được xếp loại là dynamic elastography, đo biến dạng ngang; trong khi loại trên như trong 2 bài báo thuộc về static elastography, đo biến dạng dọc.

Abstract



Purpose: To evaluate the diagnostic performance of gray-scale ultrasonography (US) and elastography in differentiating benign and malignant thyroid nodules.

Materials and Methods: This was an institutional review board–approved retrospective study with waiver of informed consent. A total of 703 solid thyroid nodules in 676 patients (mean age, 49.7 years; range, 18–79 years) were included; there were 556 women (mean age, 49.5 years; range, 20–74 years) and 120 men (mean age, 50.7 years; range, 18–79 years). Nodules with marked hypoechogenicity, poorly defined margins, microcalcifications, and a taller-than-wide shape were classified as suspicious at grayscale US. Findings at elastography were classified according to the Rago criteria and the Asteria criteria. The diagnostic performances of gray-scale US and elastography were compared. For comparison between the diagnostic performances of gray-scale US and the combination of gray-scale US and elastography, three sets of criteria were assigned: criteria set 1, nodules with any suspicious grayscale US feature were assessed as suspicious; criteria set 2, Rago criteria were added as suspicious features to criteria set 1; and criteria set 3, Asteria criteria were added as suspicious features to criteria set 1. The diagnostic performances of gray-scale US, elastography with Rago criteria, and elastography with Asteria criteria, and odds ratios (ORs) with 95% confidence intervals for predicting thyroid malignancy were compared using generalized estimating equation analysis.

Results: Of 703 nodules, 217 were malignant and 486 were benign. Sensitivity, negative predictive value (NPV), and OR of gray-scale US for the 703 nodules were 91.7%, 94.7%, and 22.1, respectively, and these values were higher than the 15.7% and 65.4% sensitivity, 71.7% and 79.1% NPV, and 3.7 and 2.6 ORs found for elastography with Rago and Asteria criteria, respectively. Specificity, positive predictive value, and accuracy for criteria set 1 were significantly higher than those for criteria sets 2 and 3 for most of the nodule subgroups that were considered.

Conclusion: Elastography alone, as well as the combination of elastography and gray-scale US, showed inferior performance in the differentiation of malignant and benign thyroid nodules compared with gray-scale US features; elastography was not a useful tool in recommending fine-needle aspiration biopsy.

© RSNA, 2012


SUMMARY


BACKGROUND

When fine-needle aspiration biopsy of thyroid nodules is performed, approximately one fourth fall into the indeterminate classification. Some authorities recommend surgical removal of all indeterminate nodules, lthough only about 10% to 30% are malignant. Real-time elastography (RTE) has been proposed to improve the diagnosis of thyroid cancer before surgery. Thyroid cancers have a harder consistency than benign thyroid nodules; RTE is a technique that uses ultrasonography to provide an estimation of tissue stiffness by measuring the degree of elasticity under the application of external light force. The goal of the current study was determine the efficacy of RTE, as compared with conventional ultrasonography (US), for differentiating malignant from benign thyroid lesions in patients being operated on for nodules with indeterminate cytology.

METHODS

The study included 102 patients (69 women) with indeterminate cytology who had conventional US and RTE. Elasticity was scored from 1 (elastic) to 4 (stiff). The median nodule diameter was 2.2 cm (range, 0.7 to 10).

RESULTS

All patients underwent surgery; 36 had a pathologic diagnosis of cancer (32 follicular variant of papillary thyroid cancer, 2 classic papillary, and 2 follicular carcinoma). The remaining 66 nodules were benign, with a final pathology of follicular adenoma in 64 and hyperplastic nodule in 2. The only ultrasound feature that was significantly associated with the diagnosis of cancer was microcalcification, and this was found in 56%. Thyroid cancer was detected in 50% of the nodules that scored 1 to 2 on RTE (good elasticity) and in 34% that scored 3 to 4 (stiff). Of the 36 patients with malignant nodules, 32 had RTE scores of 3 to 4.

Although the sensitivity was 89%, the positive predictive value was only 34% and the negative predictive value was 50%.

CONCLUSIONS

The current study did not confirm the utility of RTE for the differential diagnosis of malignancy or benignity in thyroid nodules with indeterminate cytology.



ANALYSIS and COMMENTARY

Investigators from Pisa, Italy, had previously reported that RTE was useful for making a diagnosis of malignancy in indeterminate nodules with a positive predictive value of 77% and a negative predictive value of 99% (1). The cause of the lack of confirmation of this result in the current study is unclear. The person performing RTE in this study was very experienced.


Nevertheless, there is a considerable element of subsoftware has been developed for quantitative analysis of stiffness. One technique, called “shear wave elastography,” may be more useful because it eliminates the operator-dependence of the procedure (2, reviewed in the January 2011 issue of Clinical Thyroidology). It is likely that the true utility of shear wave elastography for discrimination between benign and malignant nodules in the indeterminate category will require additional studies for validation.


— Jerome M. Hershman, MD

REFERENCES

1. Rago T, Scutari M, Santini F, Loiacono V, Piaggi P, Di Coscio G, Basolo F, Berti P, Pinchera A, Vitti P. Real-time elastosonography: useful tool for refining the presurgical diagnosis in thyroid nodules with indeterminate or nondiagnostic cytology. J Clin Endocrinol Metab 2010;95:5274– 5280, Epub September, 2010.

2.  Sebag F, Vaillant-Lombard J, Berbis J, Griset V, Henry JF, Petit P, Oliver C. Shear wave elastography: a new ultrasound imaging mode for the differential diagnosis of benign and malignant thyroid nodules. J Clin Endocrinol Metab 2010;95:5281–8. Epub September 29, 2010.

Thứ Ba, ngày 28 tháng 2 năm 2012

VÀI NHẬN XÉT VỀ TÌNH HÌNH KHẢO SÁT ARFI TỔN THƯƠNG U ĐẶC Ở GAN

VÀI NHẬN XÉT VỀ TÌNH HÌNH KHẢO SÁT ARFI TỔN THƯƠNG U ĐẶC Ở GAN:

BS NGUYỄN THIỆN HÙNG, Trung tâm Y khoa MEDIC Hoà Hảo, Tp HCM


1. SỐ BÀI CÔNG BỐ CÒN ÍT=

- 5 bài trên u gan các loại  chưa can thiệp

- 1 bài về HCC sau đốt RF

- Số ca từng loại u còn ít, HCC=25 ca, u mạch máu =35 ca, còn lại dưới 15 ca.


2. Ý KIẾN CÒN PHÂN TÁN=

- Chỉ 1 bài có giá trị ngưỡng phân biệt lành với ác tính với tốc độ ARFI=2m/s. 1 bài phân biệt u mạch máu với di căn gan=2,5m/s

- Hầu hết giá trị tốc độ ARFI của các u đặc ở gan có hiện tượng chồng lắp, không thể giúp phân biệt loại u và tính lành ác của u. Heide cho biết giá trị so sánh độ đàn hồi giữa u lành và u ác ở gan có kết quả thống kê yếu (p=0,28). Giá trị ARFI cao nhất ở HCC và thấp nhất ở vùng gan chưa thấm mỡ. Trong 81 trường hợp, giá trị ARFI đều cao ở u lành và u ác tính nên không cho phép phân biệt bằng giá trị độ đàn hồi ARFI (3). Trong khi đó, với 128 u gan (60 lành, 68 ác tính), giá trị VTQ trung bình của u gan ác tính là 3,14 m/s (average value 3,16 ± 0,80 m/s, range 1,17‒4,5 m/s), và lành tính là 1,35 m/s (average value 1,47 ± 0,53 m/s, range 0,74‒3,26 m/s), (P < 0,001). Với giá trị ngưỡng 2,22 m/s, độ nhạy, độ đặc hiệu và độ chính xác lần lượt là 89, 7%, 95,0%, và 92,2% (6).

- Về VTI= ít có mô tả. Có ý kiến cho là u ác tính và lành tính có darker color (cứng hơn) so với nền gan.



Tài liệu tham khảo:

1/ Acoustic Radiation Force Impulse Elastography in Distinguishing Hepatic Haemangiomata from Metastases: Preliminary Observations, G Davies and M Koenen, The British Journal of Radiology, 84 (2011), 939–943.

2/ Acoustic radiation force impulse elastography for the evaluation of focal solid hepatic lesions: preliminary findings, Cho SH, Lee JY, Han JK, Choi BI. Ultrasound Med Biol. 2010 Feb;36(2):202-8. Epub 2009 Dec 16.

3/ Characterization of focal liver lesions (FLL) with acoustic radiation force impulse (ARFI) elastometry, Heide R, Strobel D, Bernatik T, Goertz RS., Ultraschall Med. 2010 Aug;31(4):405-9. Epub 2010 Jul 22.

4/Acoustic radiation force impulse elastography for hepatocellular carcinoma-associated radiofrequency ablation, Hee-Jin Kwon, Myong-Jin Kang, Jin-Han Cho, Jong-Young Oh, Kyung-Jin Nam, Sang-Yeong Han, Sung Wook Lee, World J Gastroenterol 2011 April 14; 17(14): 1874-1878.

5/ Acoustic Radiation Force Impulse (ARFI) ultrasound imaging of solid focal liver lesions, A. Gallotti , M. D’Onofrio , L. Romanini , V. Cantisani , R. Pozzi Mucelli , European Journal of Radiology, Volume 81, Issue 3 , Pages 451-455, March 2012.

6/ Usefulness of Acoustic Radiation Force Impulse Imaging in the Differential Diagnosis of Benign and Malignant Liver Lesions, Tian Shuang-Ming, Zhou Ping, Qian Ying, Chen Li-Rong, Zhang Ping, Academic Radiology,Volume 18, Issue 7 , Pages 810-815, July 2011.

Thứ Hai, ngày 27 tháng 2 năm 2012

Acoustic Radiation Force Impulse (ARFI) ultrasound imaging of solid focal liver lesions

Acoustic Radiation Force Impulse (ARFI) ultrasound imaging of solid focal liver lesions, A. Gallotti , M. D’Onofrio , L. Romanini , V. Cantisani , R. Pozzi Mucelli , European Journal of Radiology, Volume 81, Issue 3 , Pages 451-455, March 2012.


Received 8 July 2010; received in revised form 17 December 2010; accepted 28 December 2010.

Abstract

Objective

The aim of this paper was to evaluate the application of ARFI ultrasound imaging and its potential value for characterizing focal solid liver lesions.

Materials and methods

In this multicentric prospective study, over a total non-consecutive period of four months, all patients underwent ARFI US examination. Two independent operators performed 5 measurements per each lesion and 2 measurements in the surrounding liver. According to the definitive diagnosis, a mean velocity value and standard deviations were obtained in each type of focal solid lesion, compared by using t-test, and the inter-operator evaluation was performed by using the Student's t-test. A comparison between the total mean values of each type of lesion and the mean value of the parenchyma was performed.

Results

40 lesions were evaluated and a total of 400 measurements were obtained. The lesions were: 6/40 (15%) hepatocellular carcinomas, 7/40 (17.5%) hemangiomas, 5/40 (12.5%) adenomas, 9/40 (22.5%) metastases and 13/40 (32.5%) focal nodular hyperplasias. The total mean values obtained were: 2.17 m/s in HCCs, 2.30 m/s in hemangiomas, 1.25 m/s in adenomas, 2.87 m/s in metastases and 2.75 m/s in FNHs. The inter-operator evaluation resulted non-statistically different (p > 0.05). A significant difference (p < 0.05) was always found by comparing adenomas to the other lesions. 160 measurements were obtained in the surrounding parenchyma, with a no significant difference between values measured in adenomas and in the sounding liver.
    
                                                                      ARFI of HCC




                                                                     ARFI of hemangioma


                                                                 ARFI of metastasis
                                                                  ARFI of FNH


Conclusions

ARFI technology with Virtual Touch tissue quantification could non-invasively provide significant complementary information regarding the tissue stiffness, useful for the differential diagnosis of focal solid liver lesions.

Thứ Bảy, ngày 25 tháng 2 năm 2012

ĐO ĐỘ CỨNG LÁCH ARFI ĐÁNH GIÁ XƠ HÓA GAN

Tóm tắt.
Cao áp TM Cửa và lách to phổ biến ở bệnh nhân bệnh gan mạn tính. Tuy nhiên, có giới hạn nghiên cứu trước đây in vivo trên tương quan giữa độ cứng lách và định giai đoạn xơ hoá gan. Nghiên cứu này nhằm mục đích đánh giá giá trị chẩn đoán của việc đo độ cứng lách (SSM), bằng công nghệ xung lực bức xạ âm (ARFI), nhằm đánh giá xơ hoá gan.
Bệnh nhân viêm gan mạn B hoặc C đủ điều kiện (n = 163) được đo cùng lúc độ cứng gan (liver stiffness measurement, LSM), độ cứng lách SSM và sinh thiết gan qua da. Đường cong đặc trưng ước tính hiệu suất chẩn đoán của SSM, với nhiều mô hình hồi quy đa tuyến tính cho LSM và SSM xác định ý nghĩa của các yếu tố được giải thích.
Kết quả chỉ ra mối tương quan có ý nghĩa giữa LSM và SSM (R^2 = 0,574, P < 0,0001). Sử dụng SSM để phân loại xơ hoá METAVIR (METAVIR F). Dùng SSM để phân loại tính điểm xơ hoá METAVIR, các khu vực dưới đường cong là 0,839 (95% CI: 0,780–0,898) cho METAVIR F1 đối với F2–4, 0,936 (95% CI: 0,898–0,975) cho F1–2 đ/v F3–4 và 0,932 (95% CI: 0,893–0,971) cho F1–3 đ/v F4, tất cả với P < 0,001. Nhiều mô hình hồi quy đa tuyến tính xác định BMI, độ cứng lách, METAVIR F3 và F4, men alanine aminotransferase, tỉ lệ prothrombin INR, sodium và tiểu cầu đếm là các yếu tố quan trọng độc lập có ‎ý nghĩa cho độ cứng gan (R^2 hiệu chỉnh = 0,724, P < 0,001). Giới tính nam, độ cứng gan, METAVIR F2, F3 và F4 cũng giải thích độ cứng lách có ý nghĩa và độc lập ( R^2 hiệu chỉnh = 0,647, P < 0,001).

ARFI độ cứng lách SSM có khả năng là một dự báo đơn độc có ích hoặc phụ trợ cho định giai đoạn xơ hoá gan.


NONTRAUMATIC SHOCKS: THORACIC ULTRASOUND





Thứ Sáu, ngày 24 tháng 2 năm 2012

MicroPure

MicroPure is a unique technology that can assist you in confirming micro calcifications, a potential marker for malignancy in breast tumors.




Toshiba America Medical Systems (Tustin, Calif.) introduced a  new advances for ultrasound imaging of the breast: MicroPure, an algorithm that aids in the detection of microcalcifications,  which enhances imaging of superficial structures and helps identify lesions.


MicroPure is an adapted filter we put onto the image to burn out bright echoes so we can better visualize calcifications,” Erin Owen, Toshiba senior manager for clinical marketing in ultrasound, explains. “Ultrasound has never been really good at looking at microcalcifications. MicroPure puts a color on it to bring out the brighter echoes.”



MicroPure is available on Aplio 400 and Aplio 500.







Owen says the technique aids in the biopsy of microcalcifications, which can be a time-consuming and laborious process. “Calcifications are often cancerous, but there’s no way to tell without a stereotactic biopsy,” she notes. “The procedure can take up to two hours, and it’s not very pleasant. With MicroPure, we can do an ultrasound-guided biopsy and be done in 15 to 20 minutes.”

Cey Weiss, MD, medical director of the Comprehensive Breast Care Center at Mercy Hospital, Chicago, Ill., has been using MicroPure for close to a year. He notes, “We like to use ultrasound for calcifications because it’s so much easier to go after them on an ultrasound than to have the patient lie on her stomach for two hours. When we have a case that we think is a good candidate for biopsy, we’ll use ultrasound.”

Ultrasound Elastography and MicroPure Imaging in the Differentiation of Benign and Malignant Thyroid Nodules

The Utility of Ultrasound Elastography and MicroPure Imaging in the Differentiation of Benign and Malignant Thyroid Nodules,  Nazan çiledag, Kemal Arda, Bilgin Kadri Arıbas, Elif Aktas and Serdal Kenan Köse, AJR: 198, March 2012


Abstract

OBJECTIVE. The aim of this study was to evaluate the utility of ultrasound elastography and MicroPure imaging in the differential diagnosis of benign and malignant thyroid nodules.

SUBJECTS AND METHODS. A total of 74 consecutive patients (65 women and nine men; age range, 21–80 years; mean [± SD] age, 51 ± 12.7 years) with thyroid nodules, who were referred for fine-needle aspiration biopsy by endocrinology or general surgery clinics, were prospectively examined using B-mode ultrasound, ultrasound elastography, and MicroPure imaging. The strain value ratio (strain index) of thyroid nodules was calculated. Patients with malignant or intermediate fine-needle aspiration biopsy results underwent thyroid surgery.

RESULTS. Using MicroPure imaging, 17 of 65 benign thyroid nodules (26.6%) and three of nine malignant thyroid nodules (33.3%) were found to contain microcalcifications. The sensitivity, specificity, negative predictive value, positive predictive value, and the accuracy rate of MicroPure imaging were 42.9%, 80.6%, 93.1%, 18.8%, and 77%, respectively. By using receiver operating characteristic analysis, the best cutoff point (2.31) was computed (area under the curve, 0.87; p < 0.001). The sensitivity, specificity, negative predictive value, positive predictive value and accuracy rate of the strain index values were 85.7%, 82.1%, 98.2%, 33.3%, and 82.4%, respectively, when the best cutoff point of 2.31 was used (p = 0.001). The p value (x = malign) was 0.96 for a strain index value higher than 2.31.

CONCLUSION. This preliminary study indicated that ultrasound elastography and MicroPure imaging can be used for the differentiation of benign and malignant thyroid nodules.

Thyroid nodules are a common finding in the general population, especially in geographic areas of iodine deficiency. Over 95% of thyroid nodules are benign and less than 5% are malignant [1]. Ultrasound is a noninvasive and easily available imaging technique for the evaluation of thyroid nodules. Many studies have reported the utility of ultrasound for the differentiation of benign and malignant thyroid nodules [1–5]. The presence of calcification, hypoechogenicity, irregular margins, absence of a halo, and predominant solid composition in the sonographic image are the key features associated with an increased risk of malignancy. However, the sensitivity, specificity, and negative and positive predictive values for these features are highly variable across patients and across different machines, and no single sonographic feature can diagnose thyroid cancer with high sensitivity and high positive predictive value [1–5].

Fine-needle aspiration biopsy of thyroid lesion is the preoperative screening method of choice worldwide, because it distinguishes benign and malignant lesions with high accuracy [6–8]. Because of its simplicity, low cost, and absence of major complications, it is the initial investigative technique in the management of thyroid diseases [6–8].

Real-time sonographic elastography is a newly developed dynamic imaging technique that displays tissue elasticity by measuring the degree of distortion under the application of an external force. Like palpation, sonographic elastography uses tissue deformation or strain that is caused by external compression and is based on the precompression and compression. Ultrasonographic elastography has been used to examine such organs as the breast [9, 10], thyroid [11], prostate [12], cervix [13], and liver [14]. This technique is a promising imaging technique that can be used for the differentiation of benign and malignant thyroid nodules. However, to our knowledge, only a limited number of studies have described the application of real-time sonographic elastography on benign and malignant thyroid nodules [15].

The MicroPure imaging algorithm (Toshiba) is an adapted filter that is used to enhance bright echoes to visualize and show calcifications, particularly microcalcifications. The purpose of this study was to evaluate the utility of ultrasound elastography and MicroPure imaging in differentiating benign and malignant thyroid nodules.

Subjects and Methods

This prospective study was approved by the Ankara Oncology Research and Education Hospital review board. Written informed consent was obtained from all patients undergoing both real-time ultrasound elastography and MicroPure imaging.

From February 2010 to April 2010, 74 consecutive patients (65 women and nine men; age range, 21–80 years; mean [± SD] age, 51 ± 12.7 years) with incompletely diagnosed thyroid nodules referred for fine-needle aspiration biopsy by endocrinology or general surgery clinics were examined prospectively. Patients with nodules larger than 40 mm, purely cystic or anechoic nodules without solid components, and shell-calcified nodules that could cause color-coding problems were excluded from the study.

All patients were examined by using gray-scale ultrasound, MicroPure imaging, and real-time sonographic elastography with a 10-MHz linear transducer (Aplio, Toshiba) during the same examination by the same operator. In sonographic elastography, the deflections occurring before and after tissue compression were calculated semiquantitatively via the shear modulus (Young modulus) and were displayed graphically in the elastogram.

The gray-scale sonography and elastography in all patients was performed by the same radiologist to prevent differences among operators and to standardize the degree of nodule pressure. All interpretations were performed before biopsy by the same operator, and the radiologist was blinded to the final diagnosis of the patients.

The sonographic examinations were performed in two steps. Gray-scale sonography and MicroPure imaging were performed for all patients in the first step, and real-time sonographic elastography was performed in the second step using the same probe during the same examination. B-mode ultrasound was performed first, then in the second step MicroPure imaging was performed, and the third step was real-time sonographic elastography.

For real-time sonographic elastography, compression was performed repeatedly in a vertical direction with light pressure and was followed by decompression. The strain value ratio (strain index) of thyroid nodule to muscle was calculated. Acquiring measurements at the same depth of the nodule and adjacent muscle was a critical issue for strain ratio calculations. Color coding of elastographic images was classified into five groups according to the Ueno classification [9]. A score of 1 indicated strain for the entire lesion (i.e., the entire lesion was evenly shaded in green) (Fig. 1); a score of 2 indicated strain in most of the lesion with some areas of no strain (i.e., a mosaic pattern of green and blue) (Fig. 2); a score of 3 indicated strain at the periphery of the lesion, with sparing of the center of the lesion (i.e., the peripheral part of the lesion was green, and the central part was blue) (Fig. 3); a score of 4 indicated no strain in the entire lesion (i.e., the entire lesion was blue, but its surrounding area was not included) (Fig. 4); and a score of 5 indicated no strain in the entire lesion or in the surrounding area (i.e., both the entire lesion and its surrounding area were blue) (Fig. 5).



Fig. 1: 56-year-old woman. Elastogram of benign thyroid nodule revealed elastographic color score of 1.

All of the patients underwent fine-needle aspiration biopsy under ultrasound guidance within 5 days of the real-time sonographic elastographic evaluation. A 21-gauge needle was used with an attached 20-mL syringe for fine-needle aspiration biopsies. The procedure was repeated one or two times. The collected material was placed onto glass slides, smeared, and equally fixed in air and 95% ethyl alcohol. Air-dried slides were stained with May-Grünwald-Giemsa stain; alcohol-fixed slides were stained using Papanicolaou method and H and E stain. The cytologic diagnoses of the thyroid nodules were compared with real-time sonographic elastography and the MicroPure imaging features. Nine patients with malignant nodules and eight patients with benign nodules in whom the diagnosis was achieved by cytologic examination underwent surgery, and the pathologic diagnoses were confirmed. Cytologically, 57 benign nodules were monitored by ultrasound for 12 months, and repeated biopsies were performed.

For the statistical analysis, quantitative variables were compared using Student t test for independent samples test, and qualitative variables were compared using the chi-square test. To determine the best of cutoff point for strain index, the receiver operating characteristic analysis was used. The quantitative data are presented as mean (± SD). A p value less than 0.05 indicated statistical significance with a 95% confidence level. All statistical analyses were performed using the SPSS packet program (version 11.5, SPSS).

Results

Seventy-four patients (age range, 21–80 years; mean age, 51 ± 12.7 years), including 65 women (age range, 21–80 years; mean age, 49.9 ± 12.3 years) and nine men (age range, 37–78 years; mean age, 58.2 ± 13.2 years), were enrolled in the study (Table 1). The maximum diameters of the evaluated thyroid nodules were 7–36 mm (mean, 17.2 ± 7.2 mm) (Table 1). Table 1 and Table 2 show the features of the patients and the benign and malignant nodules, respectively.

At ultrasound examination, 74 nodules were identified. Among 74 nodules, 56 nodules (75.7%) were solid, and 18 nodules (24.3%) were heterogeneous with cystic degeneration. Thirty-two nodules (43.2%) were hypoechoic, eight nodules (10.8%) were isoechoic, six nodules (8.1%) were hyperechoic, and 10 nodules (13.5%) were hypoechoic. Regular margins were observed in 60 nodules (81.08%), and irregular margins were seen in 14 nodules (18.9%). Calcifications were found in 17 of 65 benign nodules (26.6%) and in three of nine (33.3%) malignant nodules (Table 2). There was no statistically significant difference (p > 0.05).



Fig. 2: 32-year-old man. Elastogram of benign thyroid nodule showed elastographic color score of 2.



Fig. 3 : 48-year-old man. Elastogram of benign thyroid nodule showed elastographic color score of 3.

Fig. 4 : 56-year-old woman. Elastogram of thyroid nodule revealed elastographic color score of 4. Final diagnosis was papillary carcinoma.

Fig. 5 :
65-year-old woman. Elastogram of thyroid nodule with elastographic color score of 5. Final diagnosis was papillary carcinoma.



Fig. 6: 58-year-old woman. MicroPure (Toshiba) image of thyroid nodule showing microcalcifications. After fine-needle aspiration biopsy, diagnosis in this case was papillary carcinoma.




Fig. 7: 45-year-old woman. Elastogram showed thyroid nodule in right isthmic portion with elasticity index of 5.44, with color score of 4. After fine-needle aspiration biopsy, final diagnosis was papillary carcinoma.

Using MicroPure imaging, 17 of 65 (26.6%) benign thyroid nodules and three of nine (33.3%) malignant thyroid nodules revealed microcalcifications (Fig. 6). The sensitivity, specificity, negative predictive value, positive predictive value, and accuracy rate of MicroPure imaging was 42.9%, 80.6%, 93.1%, 18.8%, and 77%, respectively.



TABLE 1: Demographic Features of Patients Included in This Study

TABLE 2 : Characteristics of Benign and Malignant Nodules

Color coding of elastographic images was classified into five groups according to the Ueno classification [9]; of the 65 benign nodules, 41 nodules (63%) had a score of 1 or 2 (15 nodules had a score of 1, and 26 nodules had a score of 2). Of the nine malignant nodules, eight (88.8%) had a score of 4 or 5 (four nodules had a score of 4, and four nodules had a score of 5). Of the 65 benign nodules, 21 (32.3%) nodules had a score of 3. Only one of the malignant lesions (11.1%) had a color score of 3, and none of the malignant nodules had a color score of 1 or 2. Of the 65 benign nodules, two (3.0%) had a color score of 4 and one (1.5%) had a color score of 5. The sensitivity, specificity, negative predictive value, positive predictive value, and accuracy rate of strain index values were 85.7%, 82.1%, 98.2%, 33.3%, and 82.4%, respectively, when the best cutoff point of 2.31 was used (area under the curve, 0.87; p < 0.001) (Figs. 7 and 8). The p value (x = malign) was 0.96 for strain index values higher than 2.31.



Fig. 8: Results of receiver operating characteristic analysis for strain index. Diagonal segments are produced by ties. With cutoff value of 2.31, area under the curve is 0.87 ± 0.05, asymptotic 95% CI is 0.774– 0.970, and asymptotic significance level is 0.001.

Discussion

Palpation, which is one of the oldest clinical skills, provides information about the stiffness of soft tissues using external compression for physical deformation of the tissue. However, palpation is a subjective examination technique. Elasticity measurements and stiffness evaluations of soft tissues are useful in the differential diagnosis of tumor, inflammation, and normal tissue. It is generally accepted that benign soft-tissue lesions are firmer than normal tissue but softer than cancers [16–19].

Until now, the stiffness of thyroid nodules has not been an objective indicator of malignancy, although it is an important factor in the differential diagnosis of malignant nodules [16]. Although fine-needle aspiration biopsy is the best method for this purpose, it suffers the limitations of being invasive, and sampling errors are inevitable [19]. A recently developed promising imaging technique called real-time sonographic elastography reveals the physical properties of soft tissue by characterizing the difference in elasticity between the region of interest and the surrounding normal soft tissue using manual compression and deformation of the tissue. Essentially, sonographic elastography is based on the combined visualization of tissue elasticity (strain) and the velocity at which the tissue deformation occurs [20]. The degree of deformation of the soft tissue is calculated and combined with a gray-scale ultrasound image as an elastography map for the evaluation of tissue stiffness after ultrasound examination. Therefore, no extra time is needed to perform sonographic elastography.

Some of the major advantages of realtime sonographic elastography are its ease of performance, its noninvasiveness, and its suitability of use during routine ultrasound examinations. In addition, this imaging technique facilitates the dynamic visualization of lesions during compression.

Lyshchik et al. [11] prospectively evaluated the sensitivity and specificity of sonographic elastography for differentiating benign and malignant tumors of the thyroid gland. They reported that thyroid lesions, such as cysts and benign and malignant nodules, exhibit different elastographic characteristics. Cysts appear as dark lesions on elastograms, whereas solid nodular lesions are stiffer than thyroid gland tissue, and malignant lesions are significantly stiffer than benign thyroid nodules. Lyshchik et al. [11] have suggested that a strain index value greater than four is the strongest independent predictor of thyroid gland malignancy (p < 0.001) and exhibits 96% specificity and 82% sensitivity.

Kagoya et al. [19] set a strain ratio or strain index value greater than 1.5 as a predictor of thyroid malignancy. This criterion exhibits 90% sensitivity and 50% specificity. In our study, the sensitivity, specificity, and accuracy rates of the strain index values were 85.7%, 82.1%, and 82.4%, respectively, when the best cutoff point of 2.31 was used.

Dighe et al. [21] studied the differential diagnoses of thyroid nodules with ultrasound elastography using carotid artery pulsation as a compression source combined with limited external compression. They found no correlation between blood pressure and the final diagnoses. In another study, Dighe et al. [22] reported that the utility of sonographic elastography performed using carotid artery pulsation as a compression source to measure the systolic thyroid stiffness index has the potential to substantially reduce the number of fine-needle aspiration biopsies by detecting benign nodules. Although carotid artery pulsation has been used in those studies as the compression source for thyroid elastography, it has also been reported that arterial pulsations may generate compressiondecompression movements that may create interfering elastographic images with unnecessary thyroid movement and it is difficult to restrict thyroid movement [15]. Hence, in the present study, carotid artery pulsation was not used as a compression source.

Microcalcifications are also characteristic findings of malignant nodules [15]. Mixed calcifications are defined by the presence of microand macrocalcifications, and some recent studies have reported that the presence of mixed calcifications suggests an increased potential for malignancy [15]. In addition, calcification is a highly concordant finding in the evaluation by radiologists [15]. The MicroPure imaging algorithm (Toshiba) is a recently developed imaging technique that aids in the detection of the calcifications by enhancing the superficial structures.

Kurita et al. [23] evaluated the usefulness of MicroPure imaging in measuring the microcalcifications in breast lesions. They reported that MicroPure imaging improved the visualization of microcalcifications and suggested that this imaging algorithm is a clinically useful easy imaging technique in the diagnoses of microcalcifications.

Sankaye et al. [24] examined 25 women through breast sonography, and 11 breast malignancies were diagnosed. Four (16%) (three malignant and one benign) calcifications were visualized through ultrasound. All calcifications were detectable using both B-mode and MicroPure imaging. The authors suggested that all four calcifications appeared more subjectively conspicuous using MicroPure imaging than in the B-mode imaging. In our study, 17 (26.6%) of 65 benign thyroid nodules and three (33.3%) of nine malignant thyroid nodules showed microcalcifications by MicroPure imaging.

Fine-needle aspiration biopsy of thyroid nodule is widely accepted as the most accurate, sensitive, specific, and cost-effective diagnostic procedure in the preoperative assessment of thyroid nodules, with low rates of false-positive (2.3%), false-negative (0.2%), and inadequate results [6, 7]. The accuracy of the fine-needle aspiration biopsy analysis approaches 95% in the differentiation of the benign nodules from the malignant nodules of the thyroid gland [6–8]. The use of ultrasound guidance improves the diagnostic yield [8]. Organizations such as the American Thyroid Association and the American Association of Clinical Endocrinologists suggest that the original cytologic diagnosis can be accepted until the nodule grows or changes in appearance [8]. Instead of routine repeated fine-needle aspiration biopsy, several researchers recommended the use of both repeated fine-needle aspiration biopsy and clinical follow-up together [8]. Because fine-needle aspiration biopsy is used as the reference standard in the present study, limitations of fine-needle aspiration biopsy of thyroid nodule also become limitations of this study. In this study, to eliminate false-positive results, nine patients with cytologic malignancies underwent surgery, and their pathologic diagnoses were confirmed. Also, eight cytologically benign nodules were surgically removed and their pathologic diagnoses were confirmed. To reduce the false-negative results, 57 cytologic benign nodules were monitored clinically and by ultrasound for 12 months, and repeat biopsies were performed.

There are some limitations to this study. First, nodules larger than 40 mm are difficult to evaluate accurately because of the difficulties in measuring thyroid nodule elasticity. Practically, a large size can be a limitation in the nodule-to-gland or nodule-to-muscle strain index described in literature [19]. However, in our study, no single nodule was larger than 40 mm. Pure cystic anechoic nodules without solid components and shell-calcified nodules may cause some measurement problems as well, because of posterior shadow or posterior enhancement artifacts of ultrasound imaging. However, we avoided pure cystic, anechoic, and shell-calcified nodules. During sonographic elastography of the thyroid, it is important to maintain a light pressure on the probe because strong pressure may lead to a misdiagnosis [15]. In addition, carotid pulsation is another restriction in the strain index that may have a negative effect on our study; however, the radiologists were experienced in this specific area. MicroPure imaging is a novel and useful method for the detection of especially suspicious microcalcifications, but more experience is needed to evaluate the utility of MicroPure imaging in the diagnoses of microcalcifications.

In conclusion, elastography is a promising imaging technique that can assist in the differential diagnosis of malignant and benign thyroid nodules. The combination of real-time sonographic elastography, MicroPure imaging techniques, and B-mode sonography may be helpful for the improvement of the differential diagnosis of thyroid malignancies.

Received February 26, 2011.

Revision received July 20, 2011.

© American Roentgen Ray Society



Thứ Ba, ngày 21 tháng 2 năm 2012

Papillary Carcinoma từ mô giáp lạc chỗ trong tủy sống

Xin giới thiệu một tạp chí nội tiết mới của Asean. Đó là tạp chí JAFES (Journal of the ASEAN Federation of Endocrine Societies). Website là http://asean-endocrinejournal.org/. Tạp chí này mới được thành lập và tuyên bố từ hôm Hội nghị AFES 16 ở TP Hồ Chí Minh tháng 11-2011 vừa qua.

Bài về mô tuyến giáp lạc chỗ ung thư hoá sau được trích từ tạp chí nội tiết học trên: JAFES, Vol 26 n0 2, November, 2011.




Introduction

Thyroid tissue in an ectopic location is rare, occurring in 1 out of 100,000 to 300,000 persons; and is usually found in the lateral neck. Ectopic thyroid tissue developing axially is even more rare, with up to 90% of cases being lingual thyroid tissue arising embryologically from a median anlage from the pharyngeal floor. Very rarely, ectopic thyroid tissue may give rise to a carcinoma.

Carcinogenesis of ectopic thyroid tissue located in midline structures such as lingual thyroid and thyroglossal duct cysts, have a reported incidence of approximately 1%, and usually occurs during the third decade of life. Almost all cases are diagnosed post-surgically on histopathologic examination. Management of these cases is individualized.


Presentation

A 12-year old girl developed progressive bilateral lower extremity weakness and sensory deficit, difficulty in ambulation, and bowel and bladder incontinence in 2004.

She had no known exposure to ionizing radiation. Maternal and early pediatric histories were unremarkable. She had no family history of malignancy and thyroid disease. Physical examination revealed a lean build; with vital signs, height and weight appropriate for age. The thyroid gland was not enlarged. Chest and abdominal examination were unremarkable. She had full and equal pulses without peripheral edema. Neuromuscular examination revealed decreased manual muscle strength on the lower extremities, hypoesthesia from T4 dermatomal level and hyperreflexia on both lower extremities. Magnetic resonance imaging (MRI) of the thoracolumbar spine revealed a well-defined enhancing nodule in the spinal cord at the level of T3-T4. The nodule measured 1.16 cm x 1.26 cm x 1.58 cm, with intermediate signal intensity in both T1- and T2-weighted studies, with associated edema above and below the lesion from level T2 down to T8-T9 (Figure 1).


She underwent a T3-T4 laminectomy with tumor excision 3 months after initial consult (January 2005). Histopathologic exam revealed a 3.0 cm x 1.5 cm x 0.8 cm mass, microscopically composed of bland cuboidal cells with uniform ovoid nuclei and adequate amphophilic cytoplasm arranged in pseudorosettes, with some cells exhibiting pale-staining to grayish cytoplasm and rare mitotic figures (Figure 2).



Immunohistochemical staining for cytokeratin and neuron-specific enolase were positive. Ependymoma was considered in the histopathologic report of the excised mass. Two months postoperatively, the patient had gradual improvement of lower extremity weakness and was able to ambulate by herself. She was then lost to follow up.

However, in March 2009, the patient developed gradual progressive weakness of both lower extremities, leading to paralysis. A repeat MRI of the thoracic spine showed an avidly enhancing intramedullary nodule at T3-T4 level, appearing bilobed with irregular margins, measuring 1.13 cm x 1.65 cm x 1.63 cm. The nodule was slightly hyperintense in T1-weighted study (Figure 3) and hypointense on T2-weighted imaging, with some extension to the neural canal at the level of T3-T4.


A second laminectomy with tumor excision was done in May 2009. Histopathologic examination of the excised 2 cm x 1.5 cm x 0.5 cm mass revealed colloid material within the lumen of follicles or ducts (Figure 4) with papillary architecture and nuclear features consistent with papillary carcinoma. These findings were not seen in the histopathologic examination of the first surgical specimen.



Microscopic sections from the second surgical specimen stained positively for thyroglobulin, thyroid transcription factor-1 (TTF-1) and epithelial membrane antigen (EMA) (Figures 5 to 7). The pathologic diagnosis of papillary carcinoma, suggestive of a thyroid primary, supersedes the previous histopathologic diagnosis. Thyroid ultrasound was normal. Thyroid function testing was also normal: thyroid stimulating hormone (TSH) was 1.03 µIU/mL (normal value 0.35 to 4.94), total thyroxine was 9 µg/dL (normal value 4.9 to 11.7), and total triiodothyronine was 1.24 ng/mL (normal value 0.58 to 1.59). Metastatic workup including CT scans of the neck, chest and abdomen did not reveal any metastatic foci.



Papillary carcinoma of the thyroid with spinal cord metastasis was the foremost consideration. A total thyroidectomy was performed in July 2009, to confirm occult primary thyroid cancer and to facilitate ablation of residual thyroid tissue for subsequent surveillance for recurrence using radioactive iodine. Histopathologic examination of the thyroid gland revealed nodular hyperplasia after thorough sampling of the entire specimen. Two months after total thyroidectomy, whole body scan using 2 mCi Iodine-131 revealed functioning thyroid remnants in the anterior neck without undue tracer deposition seen elsewhere. Her postoperative stimulated thyroglobulin level was less than 2 ng/mL. She was placed on daily levothyroxine suppressive doses with regular monitoring of thyroid function tests and thyroglobulin level. Radioactive iodine ablation was not indicated since there was no evidence of remaining iodine-avid lesions in the spinal cord. She was placed on physical therapy and rehabilitation program after spinal surgery and thyroidectomy. The patient, now 19 years of age, remains paraplegic, with no evidence of active malignancy both clinically and on imaging studies, two years since her last surgery. Thyrotropin levels are adequately suppressed and serial results of thyroglobulin levels are undetectable.

Discussion
Thyroid tissue that is located elsewhere from its expected location anterior to the second to fourth tracheal cartilages is ectopic. Embryologically, the thyroid gland develops from a median anlage and a pair of lateral anlages. The embryologic pharyngeal floor gives rise to the median anlage, whereas the fourth and fifth branchial pouches give rise to the lateral anlage. Its descent follows the heart and great vessels and moves caudally from its origin to its location in the neck in front of the trachea. Aberrant caudal descent of the median anlage during development may give rise to an intrathoracic location of ectopic thyroid tissue. There have been reports of ectopic thyroid tissue occurring in the right ventricle of the heart, aberrant right carotid thyroid tissue, carotid bifurcation, lingual ectopic thyroid, intrathoracic ectopic thyroid, substernal goiter, intralaryngotracheal thyroid and spinal cord. Carcinomas arising from ectopic thyroid tissue are uncommon. They have been reported to arise from thyroid tissue in thyroglossal duct cysts, lateral aberrant thyroid tissue, lingual thyroid and mediastinal and struma ovarii. Most tumors in the ectopic locations have been papillary carcinomas, mixed follicular and papillary carcinomas or Hürthle cell tumors. However, a carcinoma arising from spinal ectopic thyroid tissue has never been reported in literature.


Differentiating between a metastatic thyroid carcinoma and malignant transformation of an ectopic thyroid tissue is difficult and can only be done after surgery, as in this case. There are no clinical, biochemical, or imaging parameters that may assist in determining the nature of the lesion; and histological examination is always required for definitive diagnosis. True ectopic thyroid tissue has an arterial supply independent of the cervical arteries that supply the thyroid; the cervical thyroid gland is normal or absent with no history of surgery; the cervical thyroid gland does not have a similar pathologic process as the ectopic tumor, and there is no history or evidence of thyroid malignancy. Although a metastatic papillary thyroid cancer was initially considered, the migration of papillary carcinoma from a primary thyroid to distant sites bypassing cervical lymph nodes is unusual. Also, a review of the post-thyroidectomy histopathology did not reveal malignancy in the thyroid, leading us to conclude that the tumor excised from the patient’s spinal cord was ectopic thyroid tissue that transformed into papillary carcinoma. The postoperative whole body scan that was negative for iodine avid lesions outside the thyroid bed may reflect either complete resection of tumor in the spinal cord or poor iodine avidity. She did not receive high dose radioiodine ablation, and was given a suppressive levothyroxine dose at 100 mcg daily to prevent recurrence.

Conclusion

Metastasis from a primary thyroid carcinoma must first be ruled out before considering malignant transformation of an ectopic thyroid tissue, which is a rare occurrence. There are no clinical, biochemical, or imaging parameters that may assist in determining the nature of these lesions, and histological exam is required for definitive diagnosis.

Surgical excision is the treatment of choice. Post-surgical management includes thyrotropin suppression to prevent recurrence. Radioiodine ablation was not thought to be necessary in this case, as there was no evidence of remaining iodine-avid lesions in the spinal cord.
__________________

ECTOPIC THYROID in MEDIC CENTER, HCMC, Vietnam

CASE 1
Ectopic Lingual Thyroid, Le van Tai, Nguyen Thien Hung, Medic Medical Center, HCMC, Vietnam





We report the case of a 36 year-old female patient who presents with symptoms of dysphonia (hot potato speech) due to abnormal mass at the base of the tongue. Ultrasound detects no thyroid gland at the normal site. At the base of the tongue, there is an hypoechoic mass without hypervascularity on color Doppler, which is suspected for ectopic thyroid tissue. Then Tc99m sodium pertechnetate scanning shows thyroid tissue at the base of tongue and there is no thyroid tissue in the normal location.


CASE 2:

2 Focal Ectopic Thyroid, Jasmine Thanh Xuan, Ng Thien Hung, Phan Thanh Son, Medic Medical Center

A 50 yo female patient was detected randomly with a small nodule at the base of her tongue per ENT endoscopy. This nodule does not appear on neck ultrasound but an another mass was found at hyoid region by ultrasound: solid, echo poor, well vascularization, and no thyroid gland detected at the normal site. At last, on MDCT 64, the 2 ectopic thyroid focals were revealed, one at the base of the tongue and the other, at thyrohyoid membrane.






Thứ Sáu, ngày 17 tháng 2 năm 2012

SIÊU ÂM ĐIỀU TRỊ RUN / nucleus ventralis intermedius of thalamus

Nhân bụng trung gian của đồi thị=nhận nhiều phần các bó chiếu để phân biệt từ bán cầu tiểu não đối bên (qua cuống tiểu não trên) và cầu nhạt cùng bên; hầu như toàn bộ các nhân chiếu của vỏ não vận động.
Nhân bụng trung gian của đồi thị là mục tiêu của thủ thuật xác định trong không gian chuyên biệt để điều trị chứng run, ngoài cách dùng thuốc, như deep brain stimulation, conventional thalamotomy, và gamma knife thalamotomy.

MRI hướng dẫn siêu âm tập trung điều trị (dùng cho u não trước đây) chứng run là cách điều trị mới hơn hẵn gamma knife thalamotomy vì an toàn hơn (không tia xạ).

Siêu âm được tập trung vào nhân bụng trung gian của đồi thị. Để xác định mục tiêu đích, bệnh nhân phải vẽ những vòng xoắn. Bệnh nhân nam đầu tiên 74 tuổi bị run tay P 10 năm, không thể viết được tên mình. Khi bác sĩ chạm đúng target, tay bệnh nhân giảm run, và những vòng xoắn  được vẽ đẹp hơn. Lúc bấy giờ cường độ được tăng lên với hàng ngàn chùm siêu âm hội tụ lại để đốt huỷ mô bệnh là những tế bào gây run, gọi là tạo tổn thương. Tổn thương của bệnh nhân này chỉ có 4mm đường kính.

Máy sử dụng có tên ExAblate Neuro của InSightec Ltd, cung cấp năng lượng siêu âm tập trung để huỷ mô đích, và quá trình huỷ bằng nhiệt này được theo dõi bằng MRI.

Còn trong phòng hồi sức, bệnh nhân đã có thể cầm ly nước bằng tay P mà không đổ vãi. Sau 1 tháng tay bệnh nhân không bị tái phát run.

----------------------------
nucleus ventralis intermedius of thalamus= the composite middle third of the ventral nucleus receiving in its various parts distinctive projections from the contralateral half of the cerebellum (by way of the superior cerebellar peduncle) and the ipsilateral globus pallidus; nearly all parts of the nucleus project to the motor cortex.


Nucleus ventralis intermedius thalami, the relay of cerebellar afferences, is the target of stereotactians particularly for the improvement of tremor.
Focused Deep Brain Ultrasonography Promising for Essential Tremor (ET)
Megan Brooks, March 30, 2011

Magnetic resonance (MR)–guided focused ultrasonography has been successfully used to relieve a 74-year-old man's debilitating essential tremor (ET) affecting his dominant right hand.

Uncontrollable shaking left the patient unable to use his right hand for more than a decade. After MR-guided focused ultrasonography, "the tremor was gone," W. Jeffrey Elias, MD, a neurosurgeon at the University of Virginia (UVA) in Charlottesville, noted in an interview with Medscape Medical News. "In the recovery room, he used his right hand to drink from a cup without spilling," Dr. Elias added in a UVA-issued statement. The patient has now been followed up for 1 month and he "continues to do well," Dr. Elias said. His tremor has not returned.

The ultrasonography is focused on the ventralis intermedius nucleus of the thalamus. "This is a standard trimmer target; whether we use radiofrequency thalamotomy or thalamic deep brain stimulation, we target a similar place," Dr. Elias explained.

To find their target, the team had the patient draw spirals during the procedure. At first, his hand shook violently, but as the researchers honed in on their target, the shaking subsided and his spirals became smooth. At that point, they increased the sound waves to heat and destroy the tissue, a process called "lesioning," Dr. Elias said. This particular patient's lesion was 4 mm in diameter.

This therapy is delivered with the ExAblate Neuro system from InSightec Ltd. The device delivers focused ultrasound energy to the targeted site, and the thermal destruction is monitored in real time with MR imaging (MRI).

Currently available treatments for ET outside drug therapy include deep brain stimulation, conventional thalamotomy, and gamma knife thalamotomy.
An "advantage of this new procedure [previously used to treat brain tumors] compared to gamma knife is that there is no radiation involved and thus it seems to be a safer procedure," Dr. Moro said.
"It might be superior to gamma knife thalamotomy and thus be a good treatment for tremor patients who cannot have deep brain stimulation or do not want to have an invasive treatment," she added. Only time will tell. 
"By demonstrating that MR-guided focused ultrasound can safely and effectively treat tissue deep in the brain with great precision and accuracy, we will open the door for treating a variety of conditions, such as Parkinson's disease, brain tumors, and epilepsy.

SIÊU ÂM CHẨN ĐOÁN LOẠN SẢN KHỚP HÔNG CHẮC CHẮN LÚC 6 THÁNG TUỔI

Tại Việt nam, siêu âm tham gia khám khớp hông cho trẻ sơ sinh từ 1-2 ngày tuổi từ sau kết quả một tầm soát ở 811 trẻ tại thành phố Hồ Chí Minh của Trung tâm Y khoa Medic (1998) được công bố. Tuy nhiên số bệnh nhi sau 6 tháng tuổi được khám siêu âm không nhiều, có thể bác sĩ lâm sàng quen với hình ảnh X-quang khung chậu, vì điểm cốt hóa đã cản quang rõ trên phim.

Bài trên có ý nói siêu âm khớp hông ở trẻ 6 tháng tuổi có giá trị không thua kém X-quang, lại có lợi thế là không có tia xạ gây hại cho trẻ. Nên dùng siêu âm khớp hông thay thế cho X-quang ở trẻ trên 6 tháng tuổi.