Correlation of Radiographic and High-Resolution Computed Tomography (HRCT) Features in Lower Lobe Tuberculosis With Microbiological Findings: A Study in the Konaseema Region

TL;DR

This study explores how radiographic and CT scan features of lower lobe tuberculosis correlate with microbiological results to improve accurate diagnosis.

Contribution

The study provides a focused correlation analysis of radiological and microbiological findings in lower lobe tuberculosis, highlighting diagnostic indicators.

Findings

Patchy opacities were the most common radiological abnormality in lower lobe tuberculosis.

Cavitation showed a strong correlation with microbiological confirmation of tuberculosis.

HRCT contributed to diagnosis in 8.8% of cases, highlighting its role in complex presentations.

Abstract

Objective: This study aimed to evaluate the radiographic, high-resolution computed tomography (HRCT), and microbiological characteristics of pulmonary tuberculosis (PTB) in general, with a focused correlation analysis in a subset of patients with lower lobe tuberculosis (LLTB), to aid in the accurate diagnosis and clinical differentiation of this atypical presentation.

Methods: A prospective observational study was conducted in the pulmonology, radiology, and microbiology departments of Konaseema Institute of Medical Sciences and Research Foundation, Andhra Pradesh. The study period was from December 2022 to June 2024. The study included 40 confirmed cases of LLTB, which were identified based on microbiological and radiological findings. HRCT and chest radiographs were analyzed for characteristic patterns. At the same time, microbial confirmation was obtained through Ziehl-Neelsen (ZN) staining, GeneXpert MTB/RIF assay (Cepheid, Sunnyvale, CA, USA), and culture on Löwenstein-Jensen (LJ) medium (HiMedia Laboratories Pvt. Ltd., Mumbai, India). Spearman's correlation was used to assess the correlation between radiological findings and microbiological confirmation.

Results: Patchy opacities were the most frequently observed radiological abnormality, identified in 37 (50.0%) out of 74 patients, followed by homogeneous consolidation in 31 (41.9%) and cavitation in 14 (18.9%) cases. Nodular opacities and para-pneumonic effusion were noted in nine (12.2%) and eight (10.8%) patients, respectively, reflecting the heterogeneous imaging patterns associated with LLTB. Sputum smear microscopy for acid-fast bacilli (AFB) yielded positive results in 33 (18.2%) cases, while bronchoalveolar lavage (BAL) confirmed tuberculosis in 12 (6.6%) patients. HRCT findings contributed to the diagnosis in 16 (8.8%) cases. Additionally, nine (5.0%) cases of non-resolving pneumonia and 11 (6.1%) cases presenting with hemoptysis underscored the diagnostic complexity of lower lobe involvement.

Conclusion: In conclusion, LLTB shows atypical radiological features, often mimicking pneumonia, with patchy opacities and consolidation. Cavitation is a key diagnostic indicator due to its strong microbiological correlation. A combined clinical, radiological, and microbial approach is essential for accurate diagnosis.