Diagnostic usefulness of low dose spiral HRCT in diffuse lung diseases

 

Sarvesh Patil¹, Prateek Umrikar^2*, Pratik Gaikwad³, Rahul Bujade⁴

 

Abstract              Background: These Interstitial lung diseases (ILDs) or diffuse parenchymal lung diseases are heterogeneous group of disorders characterized by varying degrees of inflammation and fibrosis in the lung parenchyma Aims and Objective: To study the diagnostic usefulness of low dose spiral HRCT in diffuse lung diseases. Methodology: This was a cross sectional study carried out in the Department of Radiology at S.R.T.R G.M.C , Ambajogai during the period of one year i.e. January 2019 to January 2020 in the patients who were suspected of Diffuse Lung Diseases clinically and underwent low dose spiral HRCT. Here the specificity and sensitivity, PPV and NPV and accuracy of the test was calculated by MEDCAL software. Result: In our study we have seen that the majority of the patients were in the age group of >60 were 29.27% followed by 50-60 were 24.39%, 40-50 were 21.95%, 30-40 were 17.07%, 20-30 were 7.32%. The majority of the patients were Males i.e. 65.85% and Female were 34.15%. As per the surgical biopsy -histopathology, diagnosis was DLS, the most common diagnosis were Idiopathic interstitial pneumonia in 33.33%, followed by Idiopathic pulmonary fibrosis (IPF) in 24.24%, Rheumatoid arthritis in 18.18%, Systemic sclerosis in 9.09%, Hypersensitivity pneumonitis in 15.15%. The Sensitivity was 96.97% and Specificity was 62.50%; Positive Predictive Value was 91.43%; Negative Predictive Value was 83.33%; Accuracy (*) was 90.24%. Conclusion: In our study the spiral HRCT was very useful in the diagnosis of diffuse lung diseases with respect to high sensitivity, specificity and diagnostic accuracy is considered.

Key words: Spiral HRCT, Diffuse Lung Disease(DLD), Interstitial Lung Disease(ILD).

 

INTRODUCTION

These Interstitial lung diseases (ILDs) or diffuse parenchymal lung diseases are heterogeneous group of disorders characterized by varying degrees of inflammation and fibrosis in the lung parenchyma , Several studies from across the globe have reported on the incidence, prevalence and the relative frequency of ILDs.^1,3 The annual incidence of ILDs has variably been reported between 1 and 31.5 per 100,000.^1,2,4 Clinicians and patients with ILD are understandably frustrated as there is no cause or cure for most of ILDs While the access to computed tomography (CT) scans of chest has surfaced an increased awareness of ILD and the prevalence of ILD in several countries has increased over time,^5,6,7 here we have seen diagnostic usefulness of low dose spiral HRCT in diffuse lung diseases

 

METHODOLOGY

This was a cross sectional study carried out in the Department of Radiology at S.R.T.R G.M.C , Ambajogai during the period of one year i.e. January 2019 to January 2020 in the patients who were suspected of Diffuse Lung Diseases clinically and underwent low dose spiral HRCT with classical radiological features of diffuse lung disease were considered as DLS on spiral HRCT later the patients also underwent histo-pathological investigation of surgical biopsy ;here the specificity and sensitivity, PPV and NPV and accuracy of the test was calculated by MEDCAL software considering the histo-pathological investigation as gold standard.

RESULT

Table 1: Distribution of the patients as per the age

The majority of the patients were in the age group of >60 were 29.27% followed by 50-60 were 24.39%, 40-50 were 21.95%, 30-40 were 17.07%, 20-30 were 7.32%.

 

Table 2: Distribution of the patients as per the sex

 The majority of the patients were Males i.e. 65.85% and Females were 34.15%.

 

Table 3: Distribution as per the surgical biopsy -histopathology diagnosis of DLS (n=33)

As per the surgical biopsy -histopathology diagnosis of DLS, the most common diagnosis were Idiopathic interstitial pneumonia in 33.33%, followed by Idiopathic pulmonary fibrosis (IPF) in 24.24%, Rheumatoid arthritis in 18.18%, Systemic sclerosis in 9.09%, Hypersensitivity pneumonitis in 15.15%.

 

Table 4a: Distribution as per the HRCT and Histopathology diagnosis

 

Table 4b: Distribution as per Sensitivity and Specificity and Accuracy

 

From Table 4a and 4b the Sensitivity was 96.97% and Specificity was 62.50%; Positive Predictive Value Was 91.43%; Negative Predictive Value was 83.33%; Accuracy (*) was 90.24%.

 

DISCUSSION

High-resolution computed tomography (HRCT) is fundamentally a sampling tool used to diagnose and evaluate the severity and anatomic distribution of a diffuse lung disease (DLD). HRCT has been proven to be superior to chest radiography (CXR) and conventional thicker-section computed tomography (CT) images for both detecting and characterizing DLD (^8,9). Accurate diagnosis of DLD is essential to devise correct management strategy and avoid mistreatment and related consequences (¹⁰). Many studies discuss the optimal technique. Some studies explored the value of limited HRCT images compared to CXR and standard CT (both limited and entire-lung images) ^11,12.  High-resolution computed tomography (HRCT) imaging of the lungs is well-established for diagnosing and managing many pulmonary diseases ^13-14. Optimal methods of acquisition and interpretation of HRCT images require knowledge of anatomy and pathophysiology ⁸, as well as familiarity with the basic physics and techniques of computed tomography. This parameter outlines the principles for performing high-quality HRCT of the lungs. HRCT is the use of thin-section CT images (0.625-mm to 1.5-mm slice thickness) with a high spatial frequency reconstruction algorithm, to detect and characterize diseases that affect the pulmonary parenchyma and small airways ¹⁵. Following the development and widespread availability of multidetector CT (MDCT) scanners capable of acquiring near-isotropic data throughout the entire thorax in a single breath-hold, 2 general approaches are available for acquiring HRCT images ¹⁶ In our study we have seen that the majority of the patients were in the age group of >60 were 29.27% followed by 50-60 were 24.39%, 40-50 were 21.95%, 30-40 were 17.07%, 20-30 were 7.32%. The majority of the patients were Males i.e. 65.85% and Female were 34.15. As per the surgical biopsy -histopathology diagnosis of DLS, the most common diagnosis were Idiopathic interstitial pneumonia in 33.33%, followed by Idiopathic pulmonary fibrosis (IPF) in 24.24%, Rheumatoid arthritis in 18.18%, Systemic sclerosis in 9.09%, Hypersensitivity pneumonitis in 15.15%. The Sensitivity was 96.97% and Specificity was 62.50%; Positive Predictive Value Was 91.43%; Negative Predictive Value was 83.33%; Accuracy (*) was 90.24%. This was similar to B. SUNDARAM ¹⁷ they found accuracy for reader 1 (R1) was 81% versus 80%, respectively, for reader 2 (R2) 70% versus 70%, and for reader 3 (R3) 64% versus 59%. Reader accuracy within their top three choices for complete versus limited examinations was: R1 91% versus 91% of cases, respectively, R2 84% versus 83%, and R3 79% versus 72% of cases. No statistically significant differences were found between the diagnosis methods (P0.28 for first diagnosis and P0.17 for top three choices)

 

CONCLUSION

In our study the spiral HRCT was very useful in the diagnosis of diffuse lung diseases with respect to high sensitivity, specificity and Diagnostic accuracy is considered.

 

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