We thank Dr. Gerard Silvestri and &#8220;Proceedings of The American Thoracic Society&#8221; for their permission to reproduce their schematic diagram of the Convex-Probe Endobronchial Ultrasound (Figure 2; Proc Am Thorac Soc Vol 6. pp 180&#8211;186, 2009). We thank &#8220;American College of Chest Physicians&#8221; for their permission to reproduce the image of the substernal thyroid biopsy (Figure 4; CHEST Journal 137.6 (2010): 1435-1436). We thank Kelly Watson, RN, for her help in preparation of the procedure video.

The protocol outlined below follows the guidelines of the institution (Roswell Park Cancer Institute, State University of New York at Buffalo, NY).
1. Initial Preparation
<ol>
	<li>Perform Endobronchial Ultrasound-guided Transbronchial Needle Aspiration (EBUS-TBNA) under moderate sedation, monitored anesthesia care (MAC), or deep sedation and general anesthesia. 
	NOTE: Patient surveys show favorable satisfaction scores with moderate sedation19, but recent data shows higher d...

The authors have nothing to disclose.

Substernal goiter was first described in 1749 by Haller23. The reported incidence of substernal or mediastinal goiter varies between 0.2% and 45% of all goiters, depending on the definition used24. More than ten definitions of substernal goiter have been proposed. By the simple clinical definition, a part of the substernal thyroid remains permanently retrosternal on physical exam without neck in hyperextension, as opposed to with neck in hyperextension as per Torre&#8217;s definition25. K...

Substernal thyroid goiter (STG) is a slow growing tumor, eventually causing symptoms in 70-80% of cases. As per literature review, between 2.5-22.6% of STG can have malignant transformation2. Compression of the trachea, esophagus, recurrent laryngeal nerve, and superior vena cava often causes symptoms like dyspnea, stridor, cough, dysphagia, dysphonia, vocal cord paralysis, Horner&#8217;s syndrome, superior vena cava syndrome, and cerebral edema. Occasional cases of overt hyperthyroidism have also been reported. A retrospective study by Shin et al. reported a positive correlation between thyroid size and presence of shortness of breath, globus sensation, and symptoms of hyperthyroidism3. This study, however, did not find a correlation between goiter size and presence of dysphagia, local discomfort, changes in voice, hemoptysis, or symptoms of hypothyroidism. Both substernal and cervical goiters carry similar malignancy risk. However, the retrosternal location makes diagnostic biopsy and treatment of STG very challenging. Most cases eventually require surgical removal using mediastinoscopy or sternotomy.
Endobronchial ultrasound (EBUS) was first described in 1992 by Hurter and Hanrath4. Over the years, EBUS-TBNA has become the procedure of choice for diagnosis and staging of non-small cell lung cancer. The reported sensitivity, specificity, and positive predictive value of EBUS-TBNA for mediastinal and hilar lymphadenopathy is 94%, 100%, and 100% respectively, with a low complication rate making it very safe, effective and superior to conventional TBNA5. However, both conventional and EBUS-guided TBNA were found to have statistically similar results for subcarinal lymph nodes6.
Two types of EBUS probes have been developed so far &#8211; the radial probe (RP-EBUS) and the curvilinear probe (CP-EBUS). RP-EBUS was the first one to become commercially available in 1999. It has a thin ultrasound probe inside a water-inflatable balloon tip. The probe rotates 360&#176;&#160;at an angle perpendicular to the axis of insertion. The inflated balloon provides a circular contact for the probe, enabling it to obtain 360&#176;&#160;view around the airways. It is used for evaluation of the central airways, assessment of airway invasion and obtaining biopsy of peripherally located lesions7,8. After the lesion is localized, radial probe must be taken out of the guide sheath in the bronchoscope&#8217;s working channel to make way for the biopsy tool. Hence, a real-time ultrasound guided biopsy cannot be performed. Three different radial probes are currently available - 20-MHz and 30-MHz miniature probes, and the 20-MHz ultra-miniature probe. The miniature probes can be inserted through the 2.8 mm working channel of a bronchoscope and reach sub-segmental airways; the higher frequency probe provides better image resolution9. With an outer diameter of 1.4 mm, the ultra-miniature probe fits into the 2 mm working channel of the smaller bronchoscope and reaches more peripheral lesions.
CP-EBUS was introduced in 2005. It is a 7.5 MHz convex probe inside a saline-inflatable balloon at the tip of the bronchoscope (Figure&#160;1). The outer diameter of the bronchoscope tube is 6.3&#160;mm, and of the tip is 6.9 mm. The inner diameter of the working channel is 2.2 mm. The scope looks at a 35&#176;&#160;forward oblique angle, with an angle of view of 80&#176;&#160;(Figure&#160;2). The convex probe itself generates a 50&#176;&#160;image, and scans parallel to the insertion axis. Ultrasound images can be obtained by either placing the probe directly over the bronchial wall using forward flexion, or by additionally inflating the balloon with saline. Water is a better conductor than air of ultrasound waves, and improves image quality. Vascular structures can be differentiated from tissues using the color Doppler mode scan. Biopsy is performed using a dedicated 22 or 21 G&#160;TBNA needle with an echogenic-dimpled tip (Figure&#160;3), which comes out at an angle of 20&#176;&#160;to the long axis of the bronchoscope. The needle has a maximum extruding stroke of 40 mm, with a safety mechanism that stops it at 20 mm to prevent excessive protrusion. The internal wire of the needle minimizes sample contamination while the needle passes through the bronchial wall. It is also used to clean up the needle after it has passed through the bronchial wall and into the targeted lesion. The optimal number of aspiration &#8220;passes&#8221; is reported to be 3-7 for a satisfactory sample, but the highest yield is from the first pass10,11. The images are processed in a dedicated ultrasound processor. Both ultrasound and white-light bronchoscopy images are simultaneously visible on the monitor, allowing for easy navigation to the site of the suspected lesion. CP-EBUS has the ability to perform real-time TBNA with direct ultrasound guidance under moderate sedation or general anesthesia. The procedure can be performed in an outpatient setting, eliminating surgery-related morbidity and need for inpatient admission.
The use of EBUS-TBNA for diagnosis of substernal thyroid is new, and has been reported in only a few case reports12-18. Based on the review of the current literature, this paper seeks to elaborate on the procedural requirements and propose EBUS-TBNA as a modality for biopsy of substernal thyroid gland. Please note that the above equipment description is more specific to Olympus Inc. There are other commercially available products as well, and minor variations do exist.

<table border="0" cellpadding="0" cellspacing="0" width="443">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:443px;">7.5-MHz Convex Probe-EBUS bronchoscope</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dedicated 22-gauge or 21-gauge TBNA needle</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ultrasound processor unit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">On-site cytopathology (optional)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Moderate sedation drugs - Benzodiazepines or fentanyl&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Deep sedation / General anesthesia drugs - Propofol or Remifentanil</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Local anesthesia (for airways) - 1% or 2% Lidocaine</td>
		</tr>
	</tbody>
</table>

substernal thyroid biopsy using endobronchial ultrasound-guided transbronchial needle aspiration

Substernal thyroid goiter (STG) represents about 5.8% of all mediastinal lesions1. There is a wide variation in the published incidence rates due to the lack of a standardized definition for STG. Biopsy is often required to differentiate benign from malignant lesions. Unlike cervical thyroid, the overlying sternum precludes ultrasound-guided percutaneous fine needle aspiration of STG. Consequently, surgical mediastinoscopy is performed in the majority of cases, causing significant procedure related morbidity and cost to healthcare. Endobronchial Ultrasound-guided Transbronchial Needle Aspiration (EBUS-TBNA) is a frequently used procedure for diagnosis and staging of non-small cell lung cancer (NSCLC). Minimally invasive needle biopsy for lesions adjacent to the airways can be performed under real-time ultrasound guidance using EBUS. Its safety and efficacy is well established with over 90% sensitivity and specificity. The ability to perform EBUS as an outpatient procedure with same-day discharges offers distinct morbidity and financial advantages over surgery. As physicians performing EBUS gained procedural expertise, they have attempted to diversify its role in the diagnosis of non-lymph node thoracic pathologies. We propose here a role for EBUS-TBNA in the diagnosis of substernal thyroid lesions, along with a step-by-step protocol for the procedure.

Endobronchial Ultrasound-guided Transbronchial Needle Aspiration (EBUS-TBNA) biopsy of substernal thyroid has been reported in eight case reports as per literature review12-18. The first case of substernal thyroid biopsy using Endobronchial Ultrasound was reported by Rosario et al. in 200612, wherein a CT chest done for metastatic work-up of prostate adenocarcinoma showed mediastinal lymphadenopathies. EBUS-TBNA of the lesion revealed a previously undiagnosed papillary thyroid carcinoma met...

Watch this Scientific Journal Video about Substernal Thyroid Biopsy Using Endobronchial Ultrasound-guided Transbronchial Needle Aspiration at JoVE.com

Substernal Thyroid Biopsy Using Endobronchial Ultrasound-guided Transbronchial Needle Aspiration

Substernal thyroid lesions are common, and need to be differentiated from malignancy. Obtaining percutaneous fine needle biopsy is not possible due to its retrosternal location. This article proposes a protocol for biopsy of substernal thyroid lesions using Endobronchial Ultrasound-guided Transbronchial Needle Aspiration (EBUS-TBNA).

Substernal thyroid goiter (STG) represents about 5.8% of all mediastinal lesions1. There is a wide variation in the published incidence rates due to the ...

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25.4K vues.  State University of New York, Buffalo.  Lésions de la thyroïde sous-sternale sont communs, et doivent être différenciées de malignité. L'obtention de la biopsie percutanée à l'aiguille fine est pas possible en raison de son emplacement rétrosternale. Cet article propose un protocole pour la biopsie des lésions de la thyroïde sous-sternale utilisant guidée par échographie endobronchique transbronchique aspiration à l'aiguille (PTBA-EEB). 