Advances in thoracic imaging have significantly transformed the diagnostic evaluation of pulmonary diseases, evolving from conventional radiography to high-resolution cross-sectional imaging. High-resolution computed tomography (HRCT) has emerged as the gold standard for evaluating lung parenchymal and airway abnormalities owing to its superior spatial resolution and ability to detect subtle structural changes. Modern multidetector CT scanners enable volumetric image acquisition with submillimeter resolution, allowing detailed visualization of diffuse and focal pulmonary pathologies.

HRCT plays a central role in the diagnosis and follow-up of a wide spectrum of pulmonary diseases, including interstitial lung diseases (ILDs), pneumoconiosis, acute inflammatory conditions, and tuberculosis. It is particularly indispensable in identifying characteristic patterns such as usual interstitial pneumonia (UIP), which is critical for the diagnosis of idiopathic pulmonary fibrosis.

Despite its excellent diagnostic accuracy, HRCT is associated with exposure to ionizing radiation, raising concerns regarding cumulative radiation dose, particularly in patients requiring repeated imaging. This has prompted the search for alternative imaging modalities capable of providing comparable diagnostic information without radiation exposure. In this context, magnetic resonance imaging (MRI) has emerged as a promising radiation-free modality, particularly for pediatric patients, pregnant women, and individuals requiring serial follow-up examinations.

However, the application of MRI in pulmonary imaging has historically been limited by several technical challenges. The lung parenchyma is characterized by low proton density and high air content, resulting in reduced signal intensity and rapid signal decay, which make conventional MRI less effective.

Furthermore, the lack of standardized imaging protocols has limited its widespread clinical application. Recent technological advances, including ultrashort echo time (UTE) and zero echo time (ZTE) sequences, have significantly improved the feasibility of pulmonary MRI by enabling earlier signal acquisition and enhanced visualization of lung structures.

In addition to structural assessment, MRI offers unique advantages in functional and tissue characterization by enabling differentiation between active inflammation and fibrosis in ILDs. This provides complementary biological information beyond the morphological assessment obtained with HRCT and may aid in disease evaluation and follow-up.

Although pulmonary MRI has demonstrated encouraging results in the assessment of selected thoracic abnormalities, its diagnostic accuracy in detecting subtle pulmonary parenchymal abnormalities remains to be fully established. In particular, the detection of ground-glass opacities, honeycombing, and other fine structural changes continues to represent a challenge for MRI compared with HRCT. Consequently, the precise role of pulmonary MRI as a complementary imaging modality in routine clinical practice remains under investigation.

Therefore, the present study was undertaken to compare the diagnostic performance of pulmonary MRI with HRCT across a spectrum of pulmonary diseases, including tuberculosis, chronic obstructive pulmonary disease, and interstitial lung diseases, and to evaluate the potential role of MRI as a complementary radiation-free imaging modality without compromising diagnostic accuracy.

MATERIALS

Study Design: This prospective comparative cross-sectional study was conducted in the Department of Radiodiagnosis at Santosh Medical College Hospital, a tertiary-care hospital in Ghaziabad, India, over an 18-month period. A total of 45 patients presenting with clinical features suggestive of pulmonary disease and meeting the eligibility criteria were enrolled during the study period.

Participants: All patients presenting with respiratory symptoms who fulfilled the inclusion criteria, including suspected or confirmed pulmonary disease, those undergoing follow-up for known pulmonary conditions, and those who provided written informed consent, were included in the study. Patients with contraindications to MRI, including ferromagnetic implants, pacemakers, metallic intraocular foreign bodies, or severe claustrophobia, were excluded to ensure patient safety.

Machines used Imaging Protocol

All HRCT examinations were performed using a Siemens Healthineers SOMATOM go.now 32-slice multidetector computed tomography (MDCT) scanner. HRCT of the chest was performed using thin-section imaging for detailed evaluation of the lung parenchyma. Image acquisition was performed using a helical technique with thin collimation. The detector configuration was 32 × 0.7–1.0 mm, with a slice collimation of 0.5–1.0 mm. Tube voltage ranged from 100–130 kVp, depending on the patient. Automatic tube current modulation (CARE Dose4D) was used with a reference tube current of approximately 120–180 mAs. Images were acquired with a slice thickness of 1.0–1.5 mm and reconstructed at 0.7–1.0 mm intervals using thin-section reconstruction for high-resolution evaluation of the lung parenchyma.

Pulmonary MRI was performed on a 1.5-T UNITED MRI system using a dedicated lung imaging protocol. The protocol included T2-SPAIR and T2-FSE sequences in the coronal plane for anatomical assessment, and T2-weighted fat-suppressed (T2WFS) and short tau inversion recovery (STIR) sequences in the axial and sagittal planes for the evaluation of pulmonary parenchyma, fluid, and inflammatory changes.

RESULTS

The study enrolled 45 patients, with a clear male predominance of 75.6 percent and a male to female ratio of approximately 3.1:1. The majority of participants were in the productive age groups, with 40 percent between 21 and 40 years and 33.3 percent between 41 and 60 years. Clinically, cough was the most common symptom, reported in 91.1 percent of patients, followed by fever in 84.4 percent and expectoration in 66.7 percent. Loss of appetite was present in 53.3 percent, while dyspnea was noted in 40 percent and chest pain in only 20 percent. This distribution reflects the predominance of infectious and inflammatory lung diseases in the study population, particularly tuberculosis and pneumonia.

When comparing parenchymal abnormalities, HRCT consistently demonstrated superior performance. It identified ten cases each of tree in bud and honeycombing, and nine cases of ground-glass opacities, whereas MRI failed to detect any of these subtle findings. MRI showed moderate sensitivity for fibrotic changes, detecting five of seven cases, and was reliable for larger lesions such as consolidation, where it detected twelve of fourteen cases, and collapse, where it matched HRCT perfectly. In mediastinal and pleural evaluation, MRI demonstrated strengths in soft tissue characterization, detecting one additional hilar lymph node, two extra cases of pleural thickening, and chest wall edema in two patients that HRCT did not reveal. Both modalities showed perfect agreement in detecting pleural effusion and pneumothorax, while HRCT was clearly superior in identifying calcified lymph nodes.

Agreement analysis showed perfect concordance for collapse and pleural effusion, almost perfect agreement for consolidation, and substantial agreement for fibrotic changes. MRI showed no agreement for ground glass opacities or honeycombing. Sensitivity and specificity analysis reinforced these results: MRI was highly sensitive for pleural effusion and consolidation but sensitivity dropped sharply for tree in bud, honeycombing, and ground glass opacities.

DISCUSSION

The demographic profile of the study population reflects the typical burden of pulmonary disease in the region, with a strong male predominance and concentration in the working age group. This pattern is clinically significant because individuals in this age bracket are at higher risk of occupational and environmental exposures, and rapid diagnosis is essential to prevent community spread, particularly in tuberculosis. The clinical symptoms, dominated by cough and fever, correlated well with radiological findings such as consolidation and tree in bud patterns, reinforcing the clinical-radiological link that underpins the comparative evaluation of HRCT and MRI.

The comparative analysis of parenchymal abnormalities revealed the critical limitations of MRI. While MRI was dependable for large, dense lesions such as consolidation and collapse, it failed to detect any cases of ground glass opacities or honeycombing. These subtle findings are essential for diagnosing early interstitial lung disease and tuberculosis, and their absence on MRI highlights the technical challenges of imaging fine airspace architecture. Statistical analysis confirmed that these differences were not random, with poor or absent agreement for tree in bud, GGO, and honeycombing. The detection gap of nearly one in four findings emphasizes that MRI cannot be relied upon as a primary diagnostic tool for early disease, as false negatives could lead to missed or delayed treatment.

Despite these limitations, MRI demonstrated clear advantages in soft tissue characterization. It detected additional hilar nodes, pleural thickening, and chest wall edema, findings that HRCT either missed or underrepresented. MRI is particularly valuable in situations where radiation exposure must be avoided, such as in children, pregnant women, or patients requiring repeated followup imaging. Taken together, the study confirms HRCT as the gold standard for fine parenchymal detail and early disease detection, while MRI serves as a safe and effective adjunct for evaluating pleural disease, mediastinal involvement, and soft tissue extension.

Funding

No funding was received for this Study.

Conflicts of interest

No conflicts of interest were declared.

Table 1: Demographic Distribution of Study Subjects N=45

Table 2. Clinical Symptoms and Mediastinal/Pleural Findings

Table 3. Comparative Detection of Parenchymal Abnormalities

Table 4. Diagnostic Yield, Agreement, and Performance Metrics (Objectives 5–10)

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