A time-honored but almost forgotten sign of COPD: sabersheath trachea as a marker of severe airflow obstruction

Transcription

1 A time-honored but almost forgotten sign of COPD: sabersheath trachea as a marker of severe airflow obstruction Poster No.: C-0958 Congress: ECR 2013 Type: Scientific Exhibit Authors: F. Ciccarese, A. Poerio, S. Stagni, D. Attinà, M. Zompatori; Bologna/IT Keywords: Lung, CT, Conventional radiography, Outcomes analysis, Observer performance, Experimental investigations, Chronic obstructive airways disease DOI: /ecr2013/C-0958 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 11

2 Purpose Saber-Sheath Trachea (ST) is a static deformity of the intra-thoracic trachea. It is defined defined by a marked narrowing in the coronal plane with widening of the sagittal diameter at the same level: coronal and sagittal diameters ratio, known as "Tracheal Index" must be <0.67-2/3, with measures conventionally taken 1 cm above the aortic arch top. [1]. Fig. 1 on page 2 Despite this finding has long been described as specific for COPD [2], the scientific interest on its pathogenesis has gradually weakened over the years, leaving many unanswered questions on it. [3-5] Thus, the aim of our study was to revisit this sign by an evaluation of the prevalence of ST in a group of patients with different stages of COPD and by a correlation with other clinical/radiological findings. Images for this section: Page 2 of 11

3 Fig. 1: Schematic representation of normal trachea (a) versus Saber-Sheath Trachea deformation (b) Page 3 of 11

4 Methods and Materials We examined chest XR of 71 patients with COPD; they were 18 women-25.4% and 53 men-74.6%; with a mean age of 70.46±10.20 years, belonging to different GOLD stages GOLD* STAGE NUMBER OF PATIENTS - % I 8/ % II 34/ % III 16/ % IV 13/ % *GOLD=Global initiative for chronic Obstructive Lung Disease. The GOLD initiative gives out the guidelines for COPD diagnosis, management and prevention and stratifies patients in 5 different stages of severity (0-IV where 0 stands for normal spirometry). In 52/ % patients we evaluated chest CT as well. We determined ST prevalence and ST correlation with Tiffenau Index, GOLD stage and radiological signs of COPD (main pattern, visual severity and emphysema visual score). Moreover, with CT as gold-standard, we analyzed XR sensitivity, specificity and accuracy, the correlation between XR and CT Tracheal Index and the intra/inter-observer agreement in the Tracheal Index measurement. Images were analyzed independently by two expert radiologists; disagreements were resolved by consensus. Results ST was found in 18/71 patients (25.4%) with a pathological Tracheal Index between 0.41 and 0.66 (mean value= 0.59). Patients with ST showed lower Tiffenau Index values than patients without ST, with a statistically significant difference (p=0.02). Page 4 of 11

5 Tiffenau Index mean value Tiffenau Index range Saber- 43.9% 24-72% Patients without Saber- 52.1% Sheath Trachea 22-76% Patients with Sheath Trachea (18) (53) Prevalence of Saber-Sheath Trachea and Tiffenau Index Likewise, ST prevalence was higher in patients with severe-very severe COPD (GOLD stages III-IV) than in patients with mild-moderate COPD (GOLD stages I-II) (p=0.05). GOLD stage Patients with Saber-Sheath Trachea Patients without Saber-Sheath Trachea Prevalence of Saber-Sheath Trachea I-II % III-IV Prevalence of Saber-Sheath Trachea in GOLD stages 37.9% However, ST resulted to be independent from other radiological signs of COPD and no correlation was observed between ST and main pattern (emphysema or bronchitis)/visual severity/emphysema visual score. Fig. 2 on page 6 Fig. 3 on page 6 The comparison between XR and CT showed a XR sensitivity, specificity and accuracy of 72.2%, 97.0%, 88.5%, with a perfect statistical correlation between XR and CT Tracheal Index (p= ). Fig. 4 on page 7 The intraclass correlation coefficient for intra-observer agreement was 0.86 for XR and 0.92 for CT; they were 0.85 for XR and 0.87 for CT regarding the inter-observer agreement. RX CT Page 5 of 11

6 Intra-Observer agreement 0.86 Inter-Observer 0.85 agreement Intra and Inter-Observer agreement Images for this section: Fig. 2: Saber-Sheath Trachea documented in both patient with centro-lobular emphysema (a;b) and in patient with a small-airway bronchitis phenotype (c;d) Page 6 of 11

7 Fig. 3: Axial CT section of a patient with severe pan-lobular emphysema and normalshaped trachea. Page 7 of 11

8 Fig. 4: Linear Regression: Tracheal Index XR-measured versus CT-measured Page 8 of 11

9 Conclusion ST is not a constant sign in patients with COPD (25.4% of prevalence), but it is linked to the functional severity, being more frequent in patients with lower Tiffenau Index and in GOLD stages III-IV. Therefore ST can be considered as a prognostic indicator that can be evaluated with the only use of the standard chest XR exam (high specificity in ST diagnosis compared with CT and perfect correlation between XR and CT Tracheal Index). Fig. 5 on page 9 With regard to the other imaging findings, the presence of ST is not linked to the main radiological patterns or to other radiological signs of obstructive disease. To conclude, we suggest that ST can be classified as one of the numerous radiological sub-phenotypes usually found in patients with COPD; it results to be independent from other radiological signs of obstructive disease and it represents an excellent marker of airway obstruction severity. For this reasons, XR tracheal evaluation should be highly recommended in all COPD patients. Images for this section: Page 9 of 11

10 Fig. 5: Comparison between Tracheal Index values measured with conventional XR (a,b) and with CT scan (c,d): Tracheal Index value were similar with both methods (coronal/ sagittal= 0.60) Page 10 of 11

11 References 1) Webb EM, Elicker BM, Webb WR (2000) Using TC to diagnose nonneoplatic tracheal abnormalities: appearance of the tracheal wall. AJR Am J Roentgenol 174: ) Green R (1978) "Saber-Sheath" Trachea: Relation to Chronic Obstructive Pulmonary Disease. Am J Roentgenol 130: ) Tsao TC, Shieh WB (1994) Intrathoracic tracheal dimensions and shape changes in chronic obstructive pulmonary disease. J Formos Med Assoc Jan; 93(1): ) Trigaux JP, Hermes G, Dubois P et al (1994) CT of Saber-Sheath Trachea: correlation with clinical, chest radiographic and functional findings. Acta Radiol May;35(3): ) Muro S, Nakano Y, Sakai H et al (2000) Distorted trachea in patients with chronic obstructive pulmonary disease. Respiration 67: Personal Information Correspondance to: Federica Ciccarese, Cardio-Thoracic Radiology, S.Orsola-Malpighi Hospital, via Massarenti 9, Bologna (Italy). Tel: ; FAX: ciccarese.f@gmail.com Page 11 of 11