High Resolution Computed Tomography Assessment of Interstitial Lung Diseases and its Correlation with Spirometry Indices

Abstract

Introduction: Interstitial lung diseases are characterized by varying degrees of inflammation and fibrosis of the lung interstitium. Lung biopsy, though the sine qua non for diagnosis is not feasible at routine health facilities due to its invasive nature. High Resolution Computed Tomography (HRCT) is now a valuable tool for the evaluation of patients with Interstitial Lung Diseases (ILD). But even HRCT is not widely available in India. Spirometry, a non-invasive modality, can be used in detecting the severity of the ILD. Spirometry carries no harmful effects of radiation, is much more easily available compared to HRCT and is also cheaper. Aim: The present study aims at an in-depth HRCT based evaluation of interstitial lung diseases with relevant spirometric correlation. Qualitative as well as semi quantitative features of interstitial lung diseases were assessed on the HRCT scan. Materials and Methods: A total of 60 patients were included in this study conducted at Government Medical College, Patiala. HRCT chest was done on Siemens-Somatom Emotion 6 slice third generation spiral CT scanner using standard protocol in supine position. Lung parenchymal abnormalities were categorized for specific diagnosis. Spirometry was performed using Medisoft Spiro Air dry rolling seal spirometer. Results: Usual Interstitial Pneumonia (UIP) was the most common ILD (55%) found in our study followed by Nonspecific Interstitial Pneumonia (NSIP) (15%) and sarcoidosis (8.33%). HRCT severity had strong and significant negative correlation with spirometry indices, especially Forced Vital Capacity (FVC), followed by Vital Capacity (VC) and least with forced expiratory volume in first second (FEV1). Conclusion: HRCT and spirometry are two simple and reliable noninvasive modalities for the diagnosis. Each ILD presents with its typical HRCT features. HRCT, with relevant clinical and laboratory information, gives a reliable diagnosis of various ILDs. Spirometry with its merits of non-invasiveness, easy availability and low cost is a reliable means for assessing the severity of disease.

Keywords

• forced vital capacity
• pulmonary disorders
• usual interstitial pneumonia
• vital capacity