eMedicine Specialties > Radiology > Chest

Trachea, Stenosis

Salomon Waizel, MD, Associate Professor of Otolaryngology, Anahuac University; Consulting Surgeon, Department of Otolaryngology, Hospital De Especialidades, National Medical Center SXXI, IMSS
Anil Khosla, MBBS, Assistant Professor, Department of Radiology, Section of Neuroradiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, Veterans Affairs Medical Center of St Louis

Updated: Jun 13, 2007

Introduction

Background

The causes of adult laryngeal and upper tracheal stenosis are trauma, chronic inflammatory diseases (eg, amyloidosis, sarcoidosis, relapsing polychondritis), benign neoplasm (eg, respiratory papillomatosis), malignant neoplasm (eg, primary tracheal, secondary invasion, metastatic), and collagen vascular diseases (eg, tracheopathia osteoplastica, Wegener granulomatosis). The most common cause of laryngotracheal stenosis continues to be trauma, which can be internal (eg, resulting from prolonged endotracheal intubation, tracheotomy, surgery, irradiation, endotracheal burns) or external (eg, blunt or penetrating neck trauma). Of these causes, it has been the authors' experiences that prolonged endotracheal intubation is the leading cause of laryngotracheal stenosis, and this condition occurs mainly in patients with multiple trauma or in those who have undergone cardiovascular surgery.

In 1880, William MacEwen first reported endotracheal intubation for anesthesia,¹ and in 1969, Lindholm reported injuries to the larynx and trachea after intubation for this purpose.² The current use of high-volume, low-pressure cuffs has almost eliminated the tracheal lesions that are caused by pressure from the cuff of the endotracheal tube. However, the number of intensive care patients who require intubation and artificial ventilation has increased dramatically.

Pathophysiology

The sequence of events that leads to laryngeal and upper tracheal stenosis in adults involves ulceration of the mucosa and cartilage, inflammatory reactions with associated granulation tissue, fibrous tissue formation, and contraction of fibrous scar tissue. Capillary perfusion pressure is a crucial consideration in mucosal injury, and mucosal ischemia is produced by direct contact with an endotracheal tube segment or by an increase in the pressure in the tube cuff.

Ulceration is the earliest laryngotracheal injury that is produced by an endotracheal tube. Ulcer healing involves regeneration of the epithelium (primary healing) or repair (secondary healing). If the regenerated epithelium fails to cover the granulation tissue (ie, pseudopapillary or nodular granulation tissue), the growth of the granulation tissue becomes exaggerated. After weeks or months, the once-vascular tissue becomes an almost avascular scar that contains only a few widely separated blood vessels.

Classification

Freitag and colleagues have recently proposed a new classification method that is based on a detailed description of the type, location, and degree of the airway stenoses.³

The type of stenoses includes 2 groups as follows:

• Structural stenosis
  • Stenosis due to all types of exophytic intraluminal malignant or benign tumors and granulation tissue
  • Extrinsic compression 
  • Narrowing due to airway distortion, kinking, bending, or buckling
  • Shrinking or scarring (eg, postintubation stenosis)
• Dynamic (functional) stenosis
  • Triangular- or tent-shaped airway, in which cartilage is damaged
  • Inward bulging of the floppy posterior membrane

The degree of the stenosis is assigned by a numerical code:

The location of the stenosis is divided into 5 regions:

• Upper one third of the trachea
• Middle one third of the trachea
• Lower one third of the trachea
• Right main bronchus
• Left main bronchus

Frequency

United States

Tracheal stenosis affects 4-13% of adults and occurs in 1-8% of neonates who have had prolonged intubation. Primary tracheal tumors are rare causes of tracheal stenosis.

Recurrent respiratory papillomatosis most commonly involves the larynx, but other areas of the respiratory tract may be affected. Some authors consider these papillomas the most common benign laryngeal tumors. Tracheobronchial involvement is usually secondary to contamination following tracheotomy.

Sarcoidosis involves the larynx in 5% of affected patients and the trachea in 1% of cases; however, this disease remains a diagnosis of exclusion. Laryngeal or tracheal involvement occurs in 50-70% of patients who have relapsing polychondritis. In cases of Wegener granulomatosis, tracheobronchial involvement occurs in 10-20% of the affected patients.

Mortality/Morbidity

Severe congenital laryngotracheal or benign acquired stenosis requires immediate airway intervention, but less than one half of the patients who have the congenital condition require tracheotomy. Individuals may seek medical care only after they have had repeated episodes of laryngotracheal infections or exercise intolerance.

Race

The authors are not aware of any racial prevalence.

Sex

To the authors' knowledge, males and females are equally affected.

Age

Postintubation tracheal stenosis is uncommon in children. Congenital stenosis is even more uncommon.

Anatomy

Gross anatomy and vascular supply

The trachea occupies the anterior and middle portions of the neck and penetrates into the superior mediastinum behind the sternum. The airway begins at the level of the cricoid cartilage and ends at the level of the sternal angle, where it bifurcates to form the 2 main stem or primary bronchi. The trachea takes the shape of a cylindrical tube, with a flattened posterior wall, wherein its skeletal structure is composed of C-shaped hyaline cartilage (tracheal rings). None of the tracheal rings are complete; they all have a posterior opening that is filled with fibroareolar connective tissue and transversely oriented smooth muscle fibers.

The trachea has 2 depressions — a superior depression that is formed by the left thyroid lobule and an inferior depression near the bifurcation made by the aorta — and its lumen is lined by mucosa that consists of a thin lamina propria and a ciliated, pseudostratified columnar epithelium. In men, the trachea is about 12 cm long and has a transverse anteroposterior (AP) diameter of 20 mm; in women, the tracheal length is approximately 11 cm, with a transverse AP diameter of 10 mm.

The superior and inferior thyroid, thymic, and right bronchial arteries provide the trachea's arterial supply. The venous blood vessels form rings that travel along the intercartilaginous spaces and flow into the esophageal and inferior thyroid veins. Tracheal innervation is provided by the vagus nerve (pulmonary plexus and laryngeal nerves) and the sympathetic nerves (cervical and dorsal ganglia).

Surgical anatomy

The indications for tracheal reconstructive operations are primary tumors, secondary tumors (thyroid, bronchogenic, esophageal), postintubation lesions, and other causes of stenoses.

The anterior surgical approach to the trachea is used for most benign lesions. It is very important to limit dissection to the anterior face of the trachea to prevent injuring the recurrent laryngeal nerves and venous plexus, which are located lateral to the trachea. The anastomosis must be made without tension.

Presentation

Acquired benign stenoses may cause symptoms a few days to weeks after extubation. Frequently, symptoms develop after a latency period of months to years.

Symptoms of dyspnea may vary from a discrete wheezing to severe asphyxia. Stridor occurs during inspiration and expiration.

Preferred Examination

A thorough patient history should be obtained, with a complete medical history that is directed toward any previous airway intervention (intubation or tracheotomy) and head and neck, thoracic, or trauma surgery. Upper airway dysfunction in acute fulminant processes may be obvious on simple examination of the patient, but chronic subtle cases are more difficult to diagnose.

Complete evaluation of the airway requires a thorough knowledge of its anatomy and physiology. The larynx, hypopharynx, and proximal trachea are assessed with an indirect mirror examination, a 70° or 90° telescope, or a flexible, fiberoptic nasolaryngoscope.

Bronchoscopy is considered the gold standard for the detection and diagnosis of tracheobronchial pathology because it permits direct visualization of the airway lumen. However, bronchoscopy has potentially hazardous complications such as profound oxygen desaturation in hypoxemic patients, tachycardia, cardiac arrhythmias, and endoscopy-induced inflammation.

Laboratory evaluation in patients with tracheal stenosis can demonstrate changes in serum electrolyte levels, acid-base balance, blood-oxygen level, and red blood cell count.

Plain AP and lateral radiographic images of the upper airway are obtained with a soft-tissue protocol during both inspiration and expiration. These studies may be used to diagnose the cause of tracheal obstruction. AP and lateral chest radiographs are also useful. In addition, high-resolution computed tomography (CT) scanning of the neck and thorax may be performed, and lung function may be analyzed.

Limitations of Techniques

The endoscopic evaluation can be subjective and dependent on the endoscopist's skills. Other technical limitations include the inability to evaluate the airway caliber and morphology beyond a high-grade stenosis of the bronchial lumen, difficulty passing the endoscope through severely narrowed airway sections, the scarce information that may be obtained about the extent of any extraluminal disease, and patient intolerance of the procedure.

Few contraindications exist for endoscopic examination, but cervical spine disorders and coagulopathy are among them. Patients who have significant airway compromise should not undergo flexible endoscopy unless rigid endoscopic equipment and an experienced team are readily available to establish an adequate airway in emergent situations. Rigid laryngotracheobronchoscopy is useful for the diagnosis and therapy of tracheal stenosis, but this procedure should be performed with general anesthesia. Flexible endoscopy is better for diagnosis and can be performed with local anesthesia.

Differential Diagnoses

Airway Foreign Body
Asthma
Epiglottitis, Acute

Other Problems to Be Considered

Patients who need prolonged endotracheal intubation and who present with a feeding problem have almost always been placed under a nothing-by-mouth (NPO) status and receive a nasogastric or nasojejunal tube. Either tube can add to tracheal damage by causing internal trauma to the esophagus, which can lead to the formation of a fistula between the 2 structures. This fistula must be identified with endoscopy, dynamic radiographic imaging studies performed with a small volume of barium or water-soluble contrast agent, or CT scanning.

Radiography

Findings

Conventional plain films (ie, AP and lateral projections and images obtained with selective high-kV filtration techniques) of the larynx provide preliminary or definitive information about foreign bodies, trauma, and other types of acute and chronic airway obstruction. These radiographs can demonstrate soft-tissue swelling, alterations of the cartilaginous framework (if it is sufficiently calcified), and the position of the air column.

Xeroradiography, with its capacity for edge enhancement, can be used to clarify intrinsic soft-tissue detail (eg, calcifications), delineate masses and stenoses, sometimes depict cartilage abnormalities (eg, fractures, erosions), and identify foreign bodies by their type and location. Unfortunately, the radiation exposure with this technique is 3-5 times that of conventional radiography, and xeroradiography is rarely used because of the high cost of leasing the equipment.

Using radiologic guidance and local anesthesia, Profili and colleagues evaluated endoscopic airway stenting in 16 patients with malignant tracheobronchial stricture.⁴ The authors reported good visualization of the stenotic tract and satisfactory control of the positioning stent before and during release. The procedure was also less invasive, more rapid, and more cost-effective compared with a combined endoscopic/fluoroscopic technique.

Degree of Confidence

The variability of calcification in the laryngeal cartilages can create a diagnostic problem.

Computed Tomography

Findings

CT scanning, sectional image data acquisition, and 3-dimensional (3-D) airway image reconstruction have become increasingly useful in head and neck surgery.

The acquired images provide detailed information regarding the tracheobronchial tree and its associated pathology. Moreover, 2-D and 3-D images that are generated by CT scan data provide additional information regarding airway pathology. A variety of computer-processing algorithms can be applied in acquired CT scan data, including multiplanar reformatting (MPR), shaded surface display (SSD), maximum or minimum intensity projection (MIP), and volume-rendering techniques (VRT), as well as a more recent technique, virtual endoscopy (VE).

Conventional coronal CT scanning allows visualization of the frontal view anatomy without a superimposed spine. This technique enables satisfactory analysis of the vertical extent of the tracheal stenosis or stricture, but conventional coronal CT scanning is only used occasionally because of its limited gray-scale ability to differentiate soft tissue. However, airway images, especially with the added sagittal projection, are excellent.

The best compromise among the combined factors of CT-scan airway measurement precision, patient breath-holding time, and total x-ray dose is the use of a 3-mm section thickness, a reconstruction interval of 1.5 mm, and a maximal pitch of 1.3-1.5, as well as the application of the edge-enhancing modus.

Inner-surface reconstructions that are calculated from helical CT scan data sets offer a diagnostic option for upper airway assessment. With special software, it is possible to create a virtual and continuous endoscopic overview of the inner surface of a hollow viscera on a monitor; these images are similar to endoscopic views and have been compared with the intraoperative findings in patients with laryngeal or tracheal stenoses. Excellent results have been reported and have led to the conclusion that virtual endoscopy offers a valuable overview for assessing the extent and location of the stenoses.

Xiong et al reported the sensitivity of CT scan-based virtual bronchoscopy (CTVB) in detecting central tumors as 93.3%, with an accuracy of 93.5%.⁵ A study by Hoppe et al resulted in a 90% sensitivity for detecting stenoses of the central airways with CTVB, a specificity of 96.6%, and an accuracy of 95.5%.⁶  Furthermore, Koletsis and colleagues demonstrated that detection of tracheal stenoses with VE was comparable to that of fiberoptic bronchoscopy, but VE had the added advantage of detecting additional stenoses beyond the areas the bronchoscope could not traverse.⁷ These findings possibly indicate that VE has high diagnostic yield in the setting of multiple stenotic lesions.

Disadvantages of CT scanning include its cost, radiation exposure, limitation to axial scans of the larynx and trachea, and a static image.

Degree of Confidence

Axial CT scan images can sufficiently evaluate the majority of airway abnormalities, but there are some limitations, including the following:

• Limited ability to detect subtle airway stenosis
• Underestimation of the craniocaudal extent of disease
• Difficulty displaying the relationships of the airway to the adjacent mediastinal structures
• Inadequate representation of the airways that are oriented obliquely to the axial plane
• Difficulty assessing the interfaces and surfaces of airways that lie parallel to the axial plane
• Generation of a large number of images for review

Despite the advantages of 2-D imaging and 3-D virtual endoscopy, both techniques also have limitations; these are related to the maximal spatial resolution of 1.5 mm, the lack of color, and the inability to depict the mucosa. The appearance of the cartilages on CT scans and MRIs also varies depending on the degree of ossification, which is not uniform and is frequently asymmetric.

Magnetic Resonance Imaging

Findings

MRI is rapidly becoming the definitive imaging modality for assessing tracheal and bronchial disorders in children. The advantages of MRI include noninvasive, high-resolution imaging with excellent soft-tissue contrast; the absence of ionizing radiation; and the identification of vascular structures without the necessity of administering iodinated contrast media. Unfortunately, standard MRI has a limited ability to depict dynamic organs, requires the use of long acquisition times, is very expensive, and is prone to motion artifacts in the images. Real-time, dynamic, cine MRI (CMRI) techniques, however, may serve as useful adjuncts for imaging moving structures.

Using CMRI, Faust and colleagues assessed airway patency and function in a study with 30 patients, equally divided among pediatric patients, adult patients, and volunteer controls.⁸ The patients who were enrolled for tracheal evaluation fell into 2 groups, those with intrinsic pathology, such as tracheomalacia, and those with extrinsic compression. Depending on the patient's clinical history, endoscopic findings, and static MRI findings, the authors were able to obtain CMRI axial, coronal, and sagittal images during the patients' quiet respiration, as well as during a variety of provocative maneuvers. The imaging findings were correlated with endoscopy when possible. 

On CMRI, dynamic tracheomalacia was seen as functional tracheal narrowing or collapse with a dynamic component; the findings coincided with the patient's respiratory cycle in all cases. In 1 patient, CMRI detected a dynamic component to a tracheal stenosis that was not appreciated by either static MRI or endoscopic evaluation. Tracheal compression that had a dynamic component and was caused by tracheomalacia, mass lesions, or anomalous vasculature was similarly demonstrated on CMRI, whereas static MRI frequently either overestimated or underestimated the degree of airway compromise that was visible with CMRI and endoscopy.

Ultrasonography

Findings

Animal studies have confirmed that ultrasound morphometric measurements of the laryngeal lumen are reliable. The transverse diameter of the trachea in the neck can be visualized by ultrasound, but the AP diameter cannot be assessed because the acoustic shadow that is generated by the air column obscures the location of the posterior tracheal wall.

Degree of Confidence

Ultrasonography has significant limitations because the laryngeal and tracheal cartilages reflect most of the sound waves with this technique. However, in a 2007 study of 19 healthy volunteers, Lakhal and colleagues compared the transverse diameter of the cricoid lumen as assessed by ultrasonography and MRI and found a strong correlation between the 2 modalities.⁹

Nuclear Imaging

Findings

Nuclear medicine imaging is seldom useful for upper airway imaging. In addition, increased radionuclide uptake has been reported in association with inflammatory arthropathies and relapsing polychondritis.

Intervention

Medical therapy for tracheal stenosis includes prevention, precise airway management, appropriate treatment of patients who require prolonged intubation, intubation by experienced personnel, continuous monitoring of the endotracheal tube-cuff pressure, intermittent endotracheal tube aspiration, and efficient management of gastroesophageal reflux and infections. Medical supportive therapy includes oxygen administration, heliox therapy, humidification, and antibiotic or steroid therapy.

Surgical management depends on the exact location and extent of the stenosis. The priority is to secure the airway. The following 3 modalities are available:

• Endoscopic management (direct resection, laser resection, or stent use)
• Percutaneous dilatation therapy
• Open surgery procedures (eg, widening, anterior cricotracheal splitting, laryngofissure creation with anterior lumen augmentation, resection, or end-to-end anastomosis)

Medicolegal Pitfalls

• The principal medicolegal pitfall is the failure to diagnose tracheal stenosis. The key to diagnosis is to have a high index of suspicion. Tracheal stenosis is a frequent condition in large hospitals, in head and neck surgical departments, and in intensive care units, but it is rare in outpatient settings.
• Some researchers do not consider the laryngotracheal lesions that are induced by prolonged endotracheal intubation to be a part of the disease; rather, the lesions are considered to be iatrogenic entities.
• In the experience of the authors of this article, the majority of cases are provided by 2 large facilities: major trauma centers and cardiovascular intensive care units. Therefore, we strongly recommend discussing with the patient's family the possibility of tracheal lesions secondary to intubation.
• In cases of tracheal stenosis caused by blunt or penetrating neck trauma, it is essential to document the condition at the first contact with the patient or as soon as the condition is detected. Also important are taking the appropriate legal action in cases where there are complications and protecting the medical staff against actions that may arise from any preexisting lesions the patient may have.

Special Concerns

• Technologic advances in CT scanning and MRI have greatly improved radiologists' ability to image the upper airway. SpiralCT scanning and fast MRI techniques allow the use of rapid acquisition speeds that decrease degradation motion artifacts caused by patients breathing and swallowing and carotid artery pulsations. SpiralCT scanners rapidly, in less than 10 seconds, acquire the complete data set through the larynx, limiting the time during which the patient needs to remain motionless. Images can then be reconstructed to create overlapping sections, and coronal, sagittal, and even 3-D images can be generated from the same data set.
• Helical CT scanning with 3-D reconstruction and virtual endoscopy in neonates and infants can prevent additional diagnostic tracheobronchoscopy in a high percentage of such patients who have tracheobronchial lesions.

Multimedia

Media file 1: The linear tomogram shows the larynx (red line), stenotic trachea (blue line), ventricular bands (blue arrow), laryngeal ventricles (green arrow), true vocal cords (red arrow), and tracheostomy site (black arrow).

Media file 2: The linear tomogram shows a stenotic segment below the left vocal cord. The double-headed arrow indicates the stenotic point in the trachea.

Media file 3: The linear tomogram shows a long stenotic tracheal segment (double-headed blue arrow) above a tracheostomy site (black arrow). The image was obtained to observe a segment of sound trachea.

Media file 4: The linear tomogram demonstrates tracheal stenosis.

Media file 5: The linear tomogram shows the larynx and a long stenotic tracheal segment (double-headed red arrow) that begins above the tracheostomy site (black arrow) and extends to two thirds of the trachea.

Media file 6: This linear tomogram was obtained from an asymptomatic patient with osteopathic tracheopathy who was undergoing elective nasal surgery.

Media file 7: This linear tomogram was obtained from a patient with a respiratory scleroma and tracheal stenosis in the cervical trachea (double-headed red arrow). The green arrow indicates the pyriform sinus, and the double-headed black arrow indicates the larynx.

Media file 8: The chest radiograph shows an intrathoracic goiter with tracheal compression and deviation (arrows).

Media file 9: This axial contrast-enhanced computed tomography scan was obtained from a patient with a deep neck abscess in the visceral compartment. The image shows significant compression and deviation of the trachea.

Media file 10: This axial contrast-enhanced computed tomography scan is from the same patient as in Image 9.

Media file 11: These axial computed tomography scans were obtained from a patient with an intrathoracic multinodular goiter that is compressing the trachea.

Media file 12: These axial CT scans were obtained from a patient with a multinodular goiter that is compressing the cervical trachea.

Media file 13: This image is a sagittal computed tomography scan reconstruction in a patient with a multinodular goiter that is compressing the tracheal lumen.

Media file 14: These computed tomography scans show an intrathoracic goiter that is compressing the trachea.

Media file 15: This magnetic resonance image was obtained from a patient with medullary thyroid carcinoma. The image shows significant compression and invasion of the trachea.

Media file 16: This axial magnetic resonance image was obtained from the same patient as in Image 15. The image shows posterolateral invasion of the trachea.

Media file 17: The computed tomography scan was obtained from a patient with papillary carcinoma in a multinodular goiter. The image demonstrates compression and deviation of the trachea (green arrow). The red arrow indicates the esophagus.

Media file 18: This resected tracheal segment shows ulceration of the mucosa and cartilage, granulation tissue, and fibrous tissue.

Media file 19: This resected tracheal segment shows internal and external changes that were secondary to prolonged endotracheal intubation.

Media file 20: This photo shows a resected tracheal segment (same segment as in Image 19).

Media file 21: This stenotic tracheal segment was obtained from a patient who underwent surgical resection and end-to-end anastomosis.

Media file 22: This resected tracheal segment is the same as that in Image 21.

Media file 23: This resected tracheal segment demonstrates a luminal obstruction that is greater than 90%.

Media file 24: This video demonstrates the results of rigid direct laryngoscopy and flexible tracheal endoscopy in a patient with significant tracheal stenosis.

Video available at http://img.medscape.com/pi/emed/ckb/radiology/336139-352740-362175-362286.wmv.

Media file 25: This video demonstrates the 90º endoscopic view in 2 patients with tracheal stenosis.

Video available at http://img.medscape.com/pi/emed/ckb/radiology/336139-352740-362175-362287.wmv.

Media file 26: This video of a 90º endoscopic tracheal view was obtained from a patient with postintubation tracheal stenosis.

Video available at http://img.medscape.com/pi/emed/ckb/radiology/336139-352740-362175-362288.wmv.

Media file 27: This video demonstrates the 90º endoscopic view in 2 patients with tracheal stenosis.

Video available at http://img.medscape.com/pi/emed/ckb/radiology/336139-352740-362175-362289.wmv.

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Keywords

upper airway stenosis, stenotic trachea, tracheal trauma, laryngotracheal stenosis, narrow airway

Contributor Information and Disclosures

Author

Salomon Waizel, MD, Associate Professor of Otolaryngology, Anahuac University; Consulting Surgeon, Department of Otolaryngology, Hospital De Especialidades, National Medical Center SXXI, IMSS
Disclosure: Nothing to disclose.

Coauthor(s)

Anil Khosla, MBBS, Assistant Professor, Department of Radiology, Section of Neuroradiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, Veterans Affairs Medical Center of St Louis
Anil Khosla, MBBS is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, American Society of Neuroradiology, North American Spine Society, and Radiological Society of North America
Disclosure: Nothing to disclose.

Medical Editor

Satinder P Singh, MD, Associate Professor of Radiology, Chief of Cardiopulmonary Radiology, Director of Cardiac CT, Director of Combined Cardiopulmonary and Abdominal Radiology, Department of Radiology, University of Alabama at Birmingham
Disclosure: Nothing to disclose.

Pharmacy Editor

Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.

Managing Editor

W Richard Webb, MD, Chief of Thoracic Imaging, Professor, Department of Radiology, University of California at San Francisco
Disclosure: Nothing to disclose.

CME Editor

Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.

Chief Editor

Eugene C Lin, MD, Consulting Radiologist, Virginia Mason Medical Center; Clinical Assistant Professor of Radiology, University of Washington School of Medicine
Eugene C Lin, MD is a member of the following medical societies: American College of Nuclear Medicine, American College of Radiology, Radiological Society of North America, and Society of Nuclear Medicine
Disclosure: Nothing to disclose.

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