CT Grade | Cases | Ground-glass opacity | Lobular septal thickening | Grid-like shadow | Consolidation shadow | Honeycomb shadow |
Mild | 13 | 69.2% | 84.6% | 23.1% | 0 | 0 |
Moderate | 31 | 64.5% | 100% | 93.5% | 25.8% | 6% |
Severe | 16 | 93.8% | 100% | 100% | 50% | 87.5% |
Citation: | GAO H, LIU Y B, XIAO M, et al. The Correlation between Computed Tomography Severity Grade and Pulmonary Function in Interstitial Lung Disease[J]. CT Theory and Applications, 2025, 34(4): 598-603. DOI: 10.15953/j.ctta.2024.305. |
Objective: To assess whether there is a correlation between CT scan severity score and pulmonary function in Interstitial Lung Disease, and provide a more reliable basis for clinical diagnosis and treatment. Materials and Methods: Sixty patients with clinical diagnosis of Interstitial Lung Disease (ILD) were collected, and chest CT and pulmonary function tests were performed at the same time. Here DLCO% and FEV1% were used as the pulmonary function indexes. The severity of the patients was assessed by CT scores as mild (range, 1~10), moderate (range 11~20), and severe (range 21~30). Correlation analysis was carried out between CT score and pulmonary function index, and the lung function parameters of patients at three grades were compared between groups and pairwise among the means. Results: As per the CT severity classification, there were 13 mild cases, 31 moderate cases, and 16 severe cases. CT score was negatively correlated with DLCO% and FEV1%. R value was −0.814 and −0.797, respectively; The comparison of the mean value of DLCO% and FEV1% among the three groups and the pairings of the mean value of DLCO% and FEV1% were statistically significant. Conclusion: There was good correlation between CT score of ILD and the pulmonary function index. The pulmonary function index of patients with different CT severity grading was statistically significant, which can provide a new basis for the clinical evaluation and diagnosis of the disease.
Interstitial lung disease (ILD) is a kind of disease characterized by interstitial inflammation and fibrosis. There are many causes[1-2] for ILD, a common disease that seriously endangers human health, which mainly involves the interstitium and alveolar cavity, leading to the loss of alveolar-capillary functional units[3]. Pulmonary function and medical imaging examination play an important role in the diagnosis and treatment of ILD, CT examination is simple and feasible with objective images, which can provide a qualitative diagnosis of interstitial lung disease[4], but it cannot further understand the patient’s lung function. Pulmonary function tests are of great significance for determining airflow limitation, judging the condition and prognosis.
However, pulmonary function tests are easily affected by subjective and other factors, and for some patients with severely impaired lung function, it is often impossible to complete routine pulmonary function tests. However, CT severity classification of ILD is rarely reported either nationally or internationally. Here we aim to grade the CT severity of the disease by combining the pulmonary function with CT examination through CT scoring, therefore creating a new basis for the clinical evaluation of the disease and providing help for the clinical diagnosis and treatment.
In this retrospective study, we evaluated 60 patients with clinical diagnosis of ILD from September 2018 to January 2020 in our hospital. After taking an informed consent from each patient, detailed demographic data, clinical history and examination, and laboratory data were reviewed, along with the CT findings.All patients had undergone chest CT and pulmonary function examination, and the following exclusion criteria were used:
(1) Unable to take a deep breath and hold it; (2) Previous history of chest surgery or restrictive lung diseases (such as granuloma, tumor, tuberculosis); (3) Serious heart disease and pulmonary hypertension; (4) Acute interstitial pneumonia.
The final study group consisted of 60 patients (36 males and 24 females, mean age (63 ±14) years; age range 27~85 years. The main clinical symptoms are cough, expectoration, shortness of breath, chest tightness, chest pain.
In all 60 patients, HRCT scan was performed on a 128-slice spiral CT scanner (Siemens). Prior to CT scanning each patient was subjected to breathing training and was told to hold his/her breath after deep inhalation. The patient was then scanned from the tip of the lung to the bottom of the lung. Scanning parameters used were as follows:
Voltage: 120 kV, tube current: intelligent tube current, screw pitch:1.5, acquisition matrix: 512×512, canning acquisition layer thickness: 0.75 mm, reconstruction layer thickness: 1 mm, layer spacing: 1 mm.
Two senior radiologists who were blinded to the patient outcome parameters, reviewed all imaging studies and recorded all findings. They independently scored the severity grading of all patients, and any differences between the two readers were subsequently resolved by consensus to obtain a consensus score. Grading standard was based on Camiciottoli4, which composed of pathological changes of lung parenchymal lesion and their respective ranges: the former include ground-glass opacity (score 1), the shadow of consolidation of the lung (score 2), irregular increasing and thickening of the interlobular septa (score 3), grid-like shadow (score 4), honeycomb shadow (score 5), lesion type score from 0 (no abnormalities) to 15 (all 5 abnormalities were detected); According to the distribution of bronchial lung segment left and right lung lobes can be divided into 10 pulmonary segments each, resulting in a total of 20 lung segments.
The score is 1 point for 1~3 affected lung segments, 2 points for 4~9 lung segment, 3 points for more than 9 affected lung segments, lesion involvement range scores from 0 point (no abnormalities in lung segments) to 15 points (all 5 lesion types are involved which affected more than 9 lung segments). The two scores are combined to obtain a total score (0~30 points). At the same time, the author innovatively proposed to grade the severity of patients according to CT scores. Patients with a score of 0 to 10 were defined as CT severity grades as mild, 11 to 20 as moderate, and 21 to 30 as severe.
Pulmonary function test (PFT) was performed with the lung function detector of JAEGER, Germany. The patient was seated during the examination, and the one-second forced breathing volume and CO dispersion were measured.
According to the patient’s body mass,age, sex and height, the predicted value was obtained, and the measured value/predicted value of the above PFT was obtained (real/expected) (%). The patient’s PFT was taken before and within three days after the CT scan.
The data were expressed as (mean ± standard) deviation and statistically analyzed using SPSS 19.0 software.
Pearson correlation test requires variables to be normally distributed, and was used to determine the correlation between CT score of each patient and FEV1% and DLCO%; The difference of FEV1 and DLCO values in patients with different CT severity classification was analyzed by one-way ANOVA, and the sample mean of the three values was analyzed by pairwise comparison of LSD-t test. Double-layer test was used for all statistical analysis, and P < 0.05 was considered statistically significant.
Frequency of various signs in 60 patients is summarized as follows: In 13 patients with mild symptoms, the ground-glass opacity was 69.2% (9/13), lobular septal thickening was 84.6% (11/13), grid-like shadow was 23.1% (3/13), and consolidation shadow and honeycomb shadow were not detected. Among the 31 patients graded as moderate, the ground-glass opacity was 64.5% (20/31), the lobular septal thickening was 100% (31/31), the grid-like shadow was 93.5% (29/31), the consolidation shadow was 25.8% (8/31), and the honeycomb shadow was 6% (2/31). Among the 16 patients with severe grade, the ground-glass opacity was 93.8% (15/16), the lobular septal thickening was 100% (16/16), the grid-like shadow was 100% (16/16), the consolidation shadow was 50% (8/16), and the honeycomb shadow was 87.5% (14/16) (Table 1).
CT Grade | Cases | Ground-glass opacity | Lobular septal thickening | Grid-like shadow | Consolidation shadow | Honeycomb shadow |
Mild | 13 | 69.2% | 84.6% | 23.1% | 0 | 0 |
Moderate | 31 | 64.5% | 100% | 93.5% | 25.8% | 6% |
Severe | 16 | 93.8% | 100% | 100% | 50% | 87.5% |
Among the 60 patients, there were 13 patients with 1~10 points, 31 patients with 11~20 points, and 16 patients with 21~30 points.
CT score was negatively correlated with DLCO% and FEV1%, with r being −0.814 and −0.797, respectively.
As mentioned earlier, 13 patients with CT scores of 1~10 was defined as mild, 31 patients with CT scores of 11~20 was defined as moderate, and 16 patients with 21~30 CT scores were categorized as severe cases (Fig.1). The mean values of DLCO% and FEV1% for 13 mild patients were (67.61±6.46) and (87.99±6.48), 31 moderate patients were (59.97±8.13) and (78.38±10.19), and 16 severe patients were (35.60±15.03) and (62.25±8.08), respectively. The pairwise comparison of the mean values between groups was statistically significant (Table 2).
CT Grade DLCO% | n | Cases FEV1% | |
Mild | 13 | 67.61±6.46 | 87.99±6.48 |
Moderate | 31 | 59.97±8.13 | 78.38±10.19 |
Severe | 16 | 35.60±15.03 | 62.25±8.08 |
The pulmonary function parameters of mild, moderate and severe groups were pairwise compared with each other (P < 0.01). |
ILD is a common clinical disease with numerous etiologies. Chest CT and pulmonary function test play an important role in the diagnosis, treatment and evaluation of the outcome of the disease[5-6]. According to the involved sites, imaging included interstitial and substantial lesions, the former mainly involved the interstitial alveolar wall, interlobular septum, interlobular septum, connective tissue around the bronchovascular bundle and pleura, interlobular fissure and other structures, the latter mainly involved the widely adjacent alveolar cavity. The corresponding CT signs are mainly reflected as ground-glass opacity, lobular septal thickening, grid-like shadow, consolidation shadow and honeycomb shadow. Previous studies have shown that ground-glass opacity and interlobular septal thickening are the early manifestations of ILD, while grid-like shadow and honeycomb shadow often indicate that the disease has developed to the middle, late and even irreversible stages[7-8]. In this group of cases, the occurrence frequency of ground-glass opacity and interlobular septum in mild patients were 69.2% and 84.6%, the occurrence frequency of grid-like shadow in moderate patients were 93.5%, and the occurrence of honeycomb shadow in severe patients were 87.5%. From another aspect, it was confirmed that the CT severity grading of ILD patients in this study was objective, accurate and consistent with clinical practice.
In addition, in this study, patients with mild ILD showed no consolidation shadows, and the occurrence frequency of such in moderate and severe patients was 25.8% and 50%. It showed that lung consolidation may also indicate the severity of patients to a certain extent; lung consolidation was a direct sign of acute inflammation, and it also suggested that moderate and severe patients were more likely to have acute infections than mild patients. Pulmonary function of a typical ILD is characterized by decreased diffusion function, restrictive ventilation disorder, and decreased lung volume[9-10].
In this study, CT scores were obtained by different imaging signs and distribution of ILD, and correlation analysis was conducted between CT scores and FEV1% and DLCO% indexes of pulmonary function, suggesting that CT scores were negatively correlated with both, with correlation coefficients of −0.814 and −0.797, respectively, suggesting a good correlation. FEV1% was the main index to judge the restricted ventilation disorder[11-12], and the CT score was negatively correlated with it, showing a good correlation, indicating that the value of FEVI decreased with the increase of CT score, and that the CT score could reflect the restricted ventilation disorder of ILD. In addition, reduced diffusion function is a relatively sensitive diagnostic index for early changes in ILD, while the ILD of carbon monoxide is mainly manifested as diffuse dysfunction, and the CT score is negatively correlated with DLCO, indicating that the CT score can be used to evaluate the lung function of patients to a certain extent.
On the basis of the CT score, the author defined the CT severity of patients from 0 to 10 as mild, from 11 to 20 as moderate, and from 21 to 30 as severe, the difference between FEV1% and DLCO% value in the three groups was statistically significant, which indicated that there was a good basis for the severity grading of ILD patients by CT score, which was consistent with the judgment of lung function index on the disease. In this way, in clinical work, CT severity grading can provide a simpler and faster method for clinical and radiologist to judge disease severity. However, in this study, only 60 patients have complete FEV1%, DLCO% data as lung function index, TLC, VC, RV that reflect changes in lung volume were not included in the evaluation and comparison of CT severity classification. It is unclear if CT severity grading can accurately reflect changes in lung volume. Many researchers have included quantitative analysis of CT pulmonary function test in the evaluation of ILD[13-16]. We will further analyze the CT severity classification and CT pulmonary function indicators, and at the same time, more patient data and conventional pulmonary function indicators should be added to classify the CT severity of pulmonary interstitial disease for increased objectivity and accuracy.
The authors declare no conflict of interest.
Funding was providing by the Shenzhen City Nanshan District Science and Technology Plan Project (Medical and Health Category) (Grant No.2018073).
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CT Grade | Cases | Ground-glass opacity | Lobular septal thickening | Grid-like shadow | Consolidation shadow | Honeycomb shadow |
Mild | 13 | 69.2% | 84.6% | 23.1% | 0 | 0 |
Moderate | 31 | 64.5% | 100% | 93.5% | 25.8% | 6% |
Severe | 16 | 93.8% | 100% | 100% | 50% | 87.5% |
CT Grade DLCO% | n | Cases FEV1% | |
Mild | 13 | 67.61±6.46 | 87.99±6.48 |
Moderate | 31 | 59.97±8.13 | 78.38±10.19 |
Severe | 16 | 35.60±15.03 | 62.25±8.08 |
The pulmonary function parameters of mild, moderate and severe groups were pairwise compared with each other (P < 0.01). |