Extracorporeal High-frequency Ultrasonography Of The Cervical Trachea And Its Preliminary Applicationing In Benign Tracheal Stenosis

Background： As a common disease in pulmonary department, benign tracheal stenosishas a gradually increasing morbidity in recent years. It can severely impair the respiratoryfunction, which secondarily leads to remote obstructive pneumonitis, causing symptomsof repeat coughing, chest tightness and dyspnea etc. Respiration interventional techniqueis the commonly treatment means of tracheal stenosis. Its short-term clinical efficacy, butlong-term with the local tissue proliferation, repair and scar formation will lead to trachealstenosis, the recurrent tate as high as40％to70％. There are at least six times reviewafter interventional treatment in first half of a year. And gradually reduce with a stablecondition. Therefore, repeat the examination and treatment will give great pain and heavymedical burden to the patient especially repeated benign cervical tracheal patient.MRI is the gold standard of non-invasive measurement of the upper airway in thehypohanynx, but too difficult to keep slowly breathing in patients with breathing difficult.Computed tomography and virtual bronchoscopy are the most commonly diagnostictechniques at present. However, CT with radiation, bronchoscope with traumatic and bothof them were costliness. So they were not suitable for repeatedly review in short term.Extracorporeal high-frequency ultrasound with non-invasive、 radio-free、 repeatableconvenient and excellent value maybe a good examining technology to patients instability clinic symptoms.In recent, there were reports concerning the measuring methods of trachea of normalpersons in foreign country, only a report about six adult patients of cervical tracheal stenosis by ultrasound was reviewed, but no study in China. So my study aims to researchand summarize the ultrasonic imaging characteristics of the health and the senosis of adultcervical trachea. The advantage and the limitation of the technology were objectivelyevaluated. And the value of the clinical application in benign tracheal stenosis will beexplored.Part One：Extracorporeal high-frequency ultrasonography of thecervical tracheaSection one：A comparative study of ultrasound and sectional specimen incervical trachea of the healthy rabbitObjective: To define extracorporeal high-frequency ultrasonography (EHFUS) findingsof the cervical trachea and its surrounding structures.Methods: EHFUS examination of the cervical trachea was performed in10healthyrabbits. The cervical tracheal shape, the tracheal wall echo and its surrounding structureswere observed in the multi-sectional of EHFUS. Comparing sonography and sectionalspecimen, we summarized the EHFUS finding in the main cervical trachea structures andits surrounding structures.Results：Sonographic findings of the cervical trachea and matching sectional specimeninformation were divided into six to analyze comparatively. The trachea is composed withdense tracheal cartilaginous rings and fibrous connective tissue. The cartilaginous shape istype C. On the anatomic transverse section，the tracheal is circle, and on the sonographictransverse view, it resembled an arch. Anterior wall resembled symmetrical crescentshaped, paraeldge were acoustic shadow. On sonographic sagittal and parasagittal views,they resembled a “string of beads”. Tracheal cartilaginous structures were whitetranslucent in anatomy, and were homogeneously hypoechoic in ultrasound imaging. Theouter tracheal edge was the tracheal external membrane in anatomy, It was the interface formed by the tracheal wall and abutting soft tissue in ultrasound imaging. It resembled ahyperechoic thin strip with continuous、smooth and sharp ledge. The inner tracheal edgewas the tracheal intimal membrane in anatomy. It was a linear hyperechoic A-M interface(Air-Mucoal, A-M) in ultrasound imaging. It resembled a smooth hyperechoic strip. Airreverberation artifact in lumen leaded the tracheal posterior wall unclearly. Sixth,Structures abutting on the trachea, including thyroid gland、strap muscle、cervicalesophagus in the neck, if present,were evaluate carefully.Conclution: we defined extracorporeal high-frequency ultrasound findings of thecervical trachea and its surrounding structures. Section Two：EHFUS imaging in cervical trachea of the health adult anddiameter measurement analysisObjective： To study features of EHFUS in120healthy adult cervical tracheas andexplore the feasibility and accuracy of part of the cervical tracheal diameter measurements,comparing with CT.Methods：EHFUS examination of the trachea was performed in120asymptomatic adultvolunteers. Comparing with CT, we define extracorporeal high-frequency ultrasound(EHFUS) imaging findings of the healthy adult cervical trachea. And define Measurementrange of TRID、TRED、TRTh、TRAS.Results：The cervical tracheal ultrasonography was basically consisted with CT section.EHFUS imaging findings in120healthy adult cervical tracheas were analied. The trachealring shape is circle or oval on the transverse view. With age increasing, the shape changedform slightly longer-class circle to circle finally to slightly cross-class circle. Ontransverse view, tracheal cartilage was homogeneously hypoechoic symmetricalcrescent-shaped. On the sagittal and parasagittal views, they resembled “a string of beads”.The tracheal outer-edge resembled a hyperechoic thin strip with continuous、smooth andsharp ledge. The inner tracheal edge resembled a smooth hyperechoic strip as A-Minterface. For some of the local fine tracheal structure, such as tracheal cartilage and thetracheal outer-edge, were more sensitive and convenient to observe by EHFUS than byCT. At the same principle, air reverberation artifact in lumen leaded the tracheal posteriorwall unclearly.The measurement results were summarized to five major groups. First, the height, theweight and TRID、TRED、TRTh of male were larger than that of female.(P﹤0.05).Second, the height, the weight and TRID、TRED、TRTh of adults were no statisticaldifference.(P>0.05). The trend of tracheal transversa-diameter measurement from T1toT4gradually slightly decreases. The average diameter TRID of T1、T2、T3、T4were15.61±1.50mm、15.30±1.75mm、15.01±1.65mm、14.91±1.73mm；The average diameter TRED of T1、T2、T3、T4were17.63±2.11mm、17.34±2.03mm、17.12±2.20mm、16.93±1.82mm. Among them, T4was the narrowest. No statistical difference betweenabutting tracheal ring measurements in each groups (P>0.05). The longest adjacentspacing of the abutting tracheal ring was from CC to T1in each group. It was notstatistically significant from T1to T4(P>0.05). It was the relevance of the values ofTRID、TRTh measured by EHFUS with that of by CT in cervical tracheal rings of thyroidlevel.The statistical results were as follow: TRID of male and female groups measured byEHFUS were (14～17)mm、(12～16) mm，the averages were(15.92±1.81) mm、(15.03±1.62) mm；TRID of female and male groups measured by CT were(15～18)mm、(13～17)mm，the averages were(16.55±1.26) mm、(15.75±1.86) mm.. Comparing TRIDmeasured by EHFUS and CT，t＝0.512, P＝0.615; t＝0.582, P＝0.678，P>0.05. It wasnot statistically significant (P>0.05). TRTh of male and female groups measured byEHFUS were1.4mm～1.7mm、1.3mm～1.7mm，the averages were (1.57±0.14) mm、(1.37±0.12) mm; TRTh of male and female groups measured by CT were (1.4～1.8) mm、(1.2～1.5) mm, the averages were1.64mm±0.12mm、1.45mm±0.15mm. ComparingTRTh measured by EHFUS and CT (t＝0.528, P＝0.621；t＝0.531, P＝0.632，P>0.05),it was not statistically significant (P>0.05).Conclusion: In the cervical tracheal ultrasonography, the cervical tracheal images of thehealthy adults were corresponded with CT section. EHFUS examination was rather simpleand fast method in part of the cervical tracheal measurement., EHFUS applied to trachealexamination was limit for Small range of EHFUS acoustic window and vision limit of airreflection. Part Two: EHFUS preliminary applicationin benign tracheal stenosisObjective To investigate the qualitative and quantitative value of EHFUS in patientswith benign tracheal stenosis.Methods23Patients(17men and6women) of cervical tracheal stenosis after treamentidentified diagnosis by bronchoscopy and pathology were selected. Among them,9caseswith emergency tracheotomy history, and9patients with tracheal stent. EHFUS findingsof the cervical tracheal stenosis group were observed in the tracheal shape regularity、the tracheal wall continuity、the tracheal wall thickness, comparing with healthy adultgroup, Tracheal stent location and shape were observed, comparing with bronchoscope.Third, the patients were observed with EHFUS according to measure their intra-diametertransversa of cervical trachea. Taking the bronchoscopy measure as control, andcompared the relevance of the values of intra-diameter transversa measured by EHFUSwith that of by bronchoscopy. Measurement of the intra-diameter transversa of cervicaltrachea. were Mean±SD Student’s t2-test was used for comparison of measurement byEHFUS and by bronchoscopy. The level for no statistical difference between EHFUSand bronchoscopy was set at P>0.05, and correlation was analyzed.Results EHFUS images of the cervical tracheal stenosis group were oberviousdifference from the healthy adult group in the tracheal shape regularity、the tracheal wallcontinuity、the tracheal wall thickness. EHFUS findings performed with the irregulartracheal shape、the tracheal wall discontinuity、interrupt or disappearance, uneven.thickness and dishomogeneousechoic of the tracheal wall. The results of Student’sFisher-test were statistical significance between the cervical tracheal stenosis group and the healthy adult group (χ2=0.962、0.876, P=0.02, P <0.05). Among23patients, Therewere9cases findings with the tracheal wall continuity interrupt, consistently with ahistory of tracheotomy、neck scar and bronchoscopy examination. EHFUS images of thetracheotomy patients performed with the anterior tracheal wall discontinuity, andirregular、 heterogeneous and limitation clumps from the interruption extended toepidermis. All metal graft could be clearly performed in EHFUS images. There were9cases with and14cases without tracheal stent., corresponded with bronchoscopyexamination. Tracheal stent on the long axis view performed with dot hyperechoic in thetracheal lumen, densely arranged in linear. Tracheal stent on the short axis view performedwith circle, attached to the inside of the tracheal wall.There were9(39.13%) patients with and14(60.78%) patients without stent placement in23cases of cervical tracheal stenosis. The length range of the intra-diameter transversaof cervical trachea or intra-diameter transversa of stent were4mm～14mm (mean:8.52mm±2.68mm) under HFUS and2mm～14mm (mean:8.39mm±2.79mm) underbronchoscopy. There were no statistical difference between EHFUS and bronchoscopy (t=0.514, P=0.613, P>0.05), but there were correlation (the correlation coefficient was0.9), P95%(0.87,0.91)Conclusion We could observe abnormal structure of tracheal anterior wall and tracheastent in patients with cervical tracheal stenosis, and more accuracy assessment of trachealstenosis within intra-diameter transversa measurement by EHFUS, which also could offerreference value to follow-up and curative effect evaluation after clinical treatment oftracheal stenosis. But too few of cases and limited disease categories in this study couldlead the sonographic analysis not to comprehensive enough.