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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 32  |  Issue : 3  |  Page : 1099-1103

Evaluation of transthoracic sonography in patients with interstitial lung diseases


1 Department of Chest Diseases and Tuberculosis, Faculty of Medicine, Menoufia University, Shebeen El-Kom, Egypt
2 El Zaitoun Specialized Hospital, Cairo, Egypt

Date of Submission22-Nov-2017
Date of Acceptance06-Feb-2018
Date of Web Publication17-Oct-2019

Correspondence Address:
Naglaa S. B. Mehana
El Matarea Cairo
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mmj.mmj_819_17

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  Abstract 

Objective
The aim of this study was to determine the diagnostic value of lung ultrasound (US) in the detection of interstitial lung diseases (ILDs), and to assess the correlations of these features with diagnostic parameters of the disease.
Background
Chest US can be used as a complementary method for the diagnosis of ILDs especially in situations where chest computed tomography is not available, where bilateral B lines, thickened pleura, irregular pleura, and subpleural lesions are found.
Patients and methods
This study was carried out on 53 patients ranging in age from 47 to 60 years (21 men and 32 women) and 23 apparently healthy persons as a control group (12 men and 11 women). All cases were subjected to a full assessment of history, clinical examination, laboratory investigations, arterial blood gases, pulmonary function test, plain chest radiography, chest high-resolution computed tomography, and transthoracic US.
Results
Our results showed that there were bilateral B-lines in combination with a thickened, irregular pleura and subpleural lesions, which are strongly suggestive of the presence of ILD. There was a statistically significant correlation between B-lines distance in millimeter, pleural line thickness in millimeter, pleural line irregularity, and abolished lung sliding that found by chest US and severity grades of high-resolution computed tomography according to the findings of semiquantitative scoring findings in ILDs patient group.
Conclusion
Bilateral B-lines in combination with a thickened, irregular pleura and subpleural lesions are strongly suggestive of the presence of ILD. These lines are not found in controls.

Keywords: B-line, irregular pleural, lung sliding, lung ultrasound, thick pleura


How to cite this article:
Mansour OF, El-Sattar Agha MA, El-Rahman El-Asdody AA, Mehana NS. Evaluation of transthoracic sonography in patients with interstitial lung diseases. Menoufia Med J 2019;32:1099-103

How to cite this URL:
Mansour OF, El-Sattar Agha MA, El-Rahman El-Asdody AA, Mehana NS. Evaluation of transthoracic sonography in patients with interstitial lung diseases. Menoufia Med J [serial online] 2019 [cited 2019 Nov 19];32:1099-103. Available from: http://www.mmj.eg.net/text.asp?2019/32/3/1099/268850




  Introduction Top


Diffuse parenchymal lung disease (DPLD) is a group of lung diseases affecting the interstitium. Interstitial lung diseases (ILDs) are characterized by progressive fibrosis of the lung leading to restriction and diminished oxygen transfer and have different etiologies, clinical presentations, radiological patterns, and histological appearance. High-resolution computed tomography (HRCT) is considered the gold standard for the diagnosis of ILDs as it is a sensitive method to assess the extent and the pattern of pulmonary fibrosis [1].

Reticular pattern involving the subpleural regions, ground glass opacities, nodular pattern, and honeycombing are the common HRCT signs of pulmonary fibrosis [2].

DPLDs as pulmonary fibrosis are characterized by the presence of multiple diffuse bilateral B-lines in chest ultrasound (US) that appear as discrete laser-like vertical hyperechoic reverberation artifacts that arise from the pleural line, extend to the bottom of the screen without fading, and move synchronously with lung sliding [3]. DPLDs account for about 15% of diseases seen in pulmonary medicine practice [4]. Diagnostic US does not depend on electromagnetic radiation, but it is based on the properties of sound waves, and hence on the mechanical and acoustic properties of tissues [5].


  Patients and Methods Top


This prospective cohort study was carried on 76 persons aged from 47 to 60 years admitted to the Chest Department of Menoufia University Hospital during the period from January 2017 to October 2017. The study group was divided into two groups.

Group 1 (the patient group): included 53 cases (21 men and 32 women). The patients were diagnosed as having ILDs in this study according to the diagnostic algorithm of ILD. Group 2 (the control group): included 23 apparently healthy persons (12 men and 11 women). The diagnosis of these cases was based on clinical presentation, serological tests, pulmonary function tests (PFTs), and HRCT findings. Informed consent was obtained from each patient and the Faculty of Medicine Ethics Committee approved this study [6].

Ethical criteria

The study was approved by the Ethics Committee of Menoufia Faculty of Medicine. After taking an informed consent and explaining the purpose of the study, all patients were submitted to the following:

First a full assessment of history is taken such as; personal history such as name, age, sex, and residence (rural or urban area), smoking habits, bird breeding, occupational exposure to different agents such as asbestosis and cobalt. History of drug intake and medical history on diseases such as tuberculosis, drug history, and family history. Then the patients underwent complete clinical examination with a special focus on clubbing, skin abnormalities, peripheral lymphadenopathy, hepatosplenomegaly, muscle tenderness, and signs of arthritis and abnormalities of the central nervous system.

Also local chest examination was done to document the presence of signs of pulmonary hypertension that may be encountered in the later stages of all chronic ILD, and to auscultation of crackles on the lungs. Also PFTs were done for all patients in the PFT unit in Menoufia University Hospital, using computerized pulmonary function apparatus 'Quark PFT 3, COSMED, Rome, Italy' and arterial blood gases were assessed as well.

Plain chest radiography: (posteroanterior and lateral views) and HRCT scans were obtained at full inspiration from the apex to the lung base with the patients in the supine position.

Finally, all patients underwent transthoracic examination using an US scanner (LOGIQ P5; GE, South Korea:The name of transthoracic Ultra-sound machine that found at chest department at Menoufia University) equipped with a 3.5-MHz convex probe and 7.5–10 MHz linear probe for lung and pleural examinations.

Pleural thickenings were defined as focal or diffuse echogenic lesions arising from the visceral or parietal pleura that are greater than 3 mm in width with or without an irregular pleural surface [7].

Presence or absence of lung sliding (the 'to-and-fro' dynamic movement of the lung during respiration) was demonstrated as fleeting dots arising from the pleural line in accordance with lung movements during respiration [8].

Recognition of B lines, which were previously called comet-tail artifacts, appeared on the screen as laser-like vertical echogenic artifacts arising from the pleural line, spreading up without fading to the edge of the screen, and moving synchronous with lung sliding [9].

As B- lines found by Ultra-sound during examination ILDs patients (three or more B- lines must be found) and must found in two more regions bilaterally as there is two lung each one divided in this study to three regions. The distance between each two adjacent B-lines was measured and is expressed in milliliters [10].

Statistical analysis

The results were statistically analyzed using an IBM personal computer and SPSS, version 24, for Windows (SPSS Inc., Chicago, Illinois, USA). Statistics were calculated in terms of mean, range, SD, percentage, and Student's t-test, which is a test of significance used for comparison between two groups of quantitative variables. A P value of less than 0.05 was considered significant; a P value of less than 0.01 was considered highly significant; and a P value of greater than 0.05 was considered insignificant [11].


  Results Top


The study was conducted on 53 cases, 32 (60.4%) women and 21 (39.6%) men. The majority of our patients were smokers, 40 (75.5%) in number; about 22 (55%) of them were passive smokers; and 13 (24.5%) were nonsmokers. Large portions, almost all of them (100%), presented with dyspnea, 39 (73.60%) presented with dry cough, while there was productive cough in about 14 (26.40%). Fourteen (26.4%) of the patients had wheezy chest. Additional extrapulmonary manifestations were recorded as clubbing of finger in 38 (71.7%). Inspiratory Velcro crackles were detected by auscultation in 39 (71.7%) of patients which are defined as bilateral fine crackles that are present throughout the inspiratory time and are persisting after several deep breaths [Table 1].
Table 1: Demographic and clinical data as well as the diagnosis of the underlying disease in patients of the studied groups

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All cases of the patients groups were found to have bilateral diffuse B-lines with (minimum–maximum) distance of 3–7 mm; 21 (39.6%) of the studied cases in the groups had irregular, thickened fragmented pleural line with abolished lung sliding (28.3%); 20 had subpleural alterations in comparison to control cases who had smooth regular pleura with no B-line at the time of examination [Table 2].
Table 2: Thoracic ultrasonography parameters in the studied groups

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It was found that the distance between each of the two adjacent B-lines positively correlated with the severity of the disease on chest HRCT which were assessed by the semiquantitative scoring system [Table 3].
Table 3: Correlations of ultrasonographic pleural findings and severity grades of high-resolution computed tomography semiquantitative scoring findings in interstitial lung disease patients

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Well-established fibrosis gives rise to a reticular pattern or honeycombing in HRCT. In US examination of these patients, the B-lines appear clearly visible and widely separated from each other (7 mm), giving the description of lung rockets. Early stages of ILDs even before thickening of the subpleural interlobular septa give ground glass areas in HRCT. US examination of these areas gave numerous B-lines with a narrow distance between them (3 mm) [Table 3].

It was found that the distances between each of the two adjacent B-lines inversely correlated with partial arterial oxygen pressure [Table 4].
Table 4: Correlation of pleural line thickness in millimeter and partial pressure of oxygen (mmHg) in interstitial lung disease patients and controlled group

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There was a significant difference in the median value of pleural thickness (mm) between all groups involved. Also there was a significant difference in the percentage of patients with irregular pleura and absent or reduced lung sliding between mild, moderate, and severe groups. Moreover, all severe cases showed irregular pleural lines over whole lung (100%), thickened pleura, and nearly absent lung sliding. On the other hand, all moderate and mild cases showed smooth, regular pleural line with demonstrated normal lung sliding [Table 5].
Table 5: Comparing between studied patients and controlling groups concerning the pulmonary function tests, partial pressure of oxygen (mmHg), and plural thickness (mm)

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There was a significant difference between US finding (such as pleural thickness in millimeter, irregular pleura, and absent or reduced lung sliding) and PFT restrictive pattern as most of cases with thickened, fragmented irregular pleural line with abolished lung sliding had very severe restriction [Table 6].
Table 6: Correlations of ultrasonographic pleural findings and severity grades of pulmonary function test restrictive pattern in interstitial lung disease patient groups

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  Discussion Top


Normal lung contains much air and little water, so no reflection of the US beams occurs and normally no B-line artifacts appear. When the subpleural septate are thickened by water or fibrosis, a high impedance gradient occurs between these structures and the surrounding air causing reflection of the beams, which create a phenomenon of resonance. The beam laser-like ray extended from the lung surface to the edge of the screen [12].

In our study, the majority of our patients, more women than men, were passive smokers. Large portion of patients presented with dyspnea and dry cough. Additional extrapulmonary manifestations were recorded as clubbing of finger in most cases, in agreement with Behr et al. [13], who found that dyspnea at rest or on exertion is a common presenting symptom in 90% of cases of ILD. Dry or productive cough of nonpurulent sputum is also a common feature in up to 80% of ILD patients.

Jacob et al. [14], who studied 132 ILDS patients, agreed that of all the patients assessed, 83 (63%) presented velcro crackles in the respiratory auscultation. Patients with velcro crackles usually had more frequent cough and dyspnea at the moment of diagnosis. Forced vital capacity and lung diffusion capacity for carbon monoxide were lower in these patients and all patients with final idiopathic lung fibrosis diagnosis presented with velcro crackles.

All cases of the studied groups had bilateral diffuse B-lines with a minimum–maximum distance of 3.1–8 mm. Of these, 39.6% had irregular, thickened fragmented pleural line with abolished lung sliding; 28.3 had subpleural alterations compared with controls. Suzan et al. [15] agreed that the most predominant artifact type among patients with ILD was B-lines; 47.6% of the studied patients had thickened and interrupted or irregular pleura. Abolished lung sliding was present in 23.8% of ILD patients compared with controls, which also agree with Gargani et al. [16].

This also came in agreement with Hasan and Makhlouf [17], whose study was conducted on 61 patients with ILDs. By transthoracic chest US, all patients had diffuse bilateral B-lines on both sides of the lung.

It was found that the distance between each of the two adjacent B-lines positively correlated with the severity of the disease on chest HRCT, which were assessed by the semiquantitative scoring system [18].

Assayag et al. [19] agreed with the results and reported that B-lines appear obvious and widely separated from each other in patients with well-established fibrosis in HRCT. Well-established fibrosis gives rise to a reticular pattern or honeycombing in HRCT.

Bouhemed et al. [20] agreed with the finding that multiple B-lines 7 mm apart are caused by thickened interlobular septa, while B-lines 3 mm or less apart are caused by ground glass areas.

There was a significant difference in pleural thickness in millimeter and percentage of patients with irregular pleura and absent or reduced lung sliding between PFT restrictive pattern groups as most of the cases with thickened, fragmented irregular pleural line with abolished lung sliding had very severe restriction.

Elbouhy et al. [21] disagree with the finding that the distance between the B-line increases in ground glass areas of up to 5 mm and reaches to 7.5 mm in reticular pattern or honeycombing in HRCT.

Also Sperandeo et al. [22] who studied 84 consecutive patients compared with those from a sample of 162 healthy patients and reported that B-lines appear obvious and widely separated from each other in patients with well-established fibrosis in HRCT; in addition, the B-lines seem numerous with a narrow distance between them in those with early ILDs, also found that the distance between each of the two adjacent B-lines positively correlated with the degree of interstitial affection on using the Warrick scoring system on HRCT.

Transthoracic lung US has many advantages over HRCT; it is a bedside procedure widely available, easily performed, inexpensive, requires neither ionizing radiation nor a contrast medium and is therefore readily and largely accepted by the patient. In addition, the surface of the lung can be easily studied by US; therefore, the B-lines are quickly detected using either low-frequency (3.5 MHz) or high-frequency (7.5 MHz) transducers [23].

In critically ill patients, portable machines even without Doppler power can be sufficient for a complete and detailed lung assessment. Finally, US is useful in situations where HRCT is not available or undesirable, as in prehospital emergencies and in pregnancy and when a patient cannot be transported out of the ICU because of severe disease [24].


  Conclusion Top


Chest US is an effective noninvasive modality that requires neither ionizing radiation nor a contrast medium. Chest US can be used as a complementary method for the diagnosis of ILDs, especially in situations where chest computed tomography is not available. Bilateral B-lines in combination with a thickened, irregular pleura and subpleural lesions are strongly suggestive of the presence of ILD. Increasing B-lines distance can be used as a surrogate marker of pulmonary function deterioration and for the presence of fibrosis on computed tomography. Chest US still has the limitations of degraded image quality in obese patients and of being operator dependent.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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