Paranasal sinuses (PNS) are air-filled spaces within the skull that play essential roles in respiration, voice modulation, and reducing cranial weight. The four paired sinuses—maxillary, ethmoid, frontal, and sphenoid—are prone to a range of pathological conditions, including inflammatory diseases, anatomical variations, and neoplastic processes, which can significantly impact patient health and require accurate diagnosis for effective management [1].

Multidetector computed tomography (MDCT) has revolutionized PNS imaging by offering superior resolution, multiplanar reconstructions, and detailed visualization of bony and soft tissue structures. Traditional radiography, though previously used, lacks sensitivity for detecting sinus pathology, particularly in the ethmoid and sphenoid sinuses [2]. MDCT, on the other hand, provides an accurate assessment of mucosal thickening, air-fluid levels, and bony involvement, making it the preferred modality for evaluating chronic rhinosinusitis, fungal infections, and sinonasal tumors [3].

A detailed understanding of anatomical variations is critical, as structures such as a deviated nasal septum, concha bullosa, and Haller cells can predispose individuals to sinus drainage obstruction and recurrent infections [4]. Additionally, early detection of neoplastic conditions through MDCT enables timely intervention, improving patient outcomes [5].

This study aims to evaluate the role of MDCT in diagnosing various PNS pathologies, identifying anatomical variations, and correlating imaging findings with clinical presentations. The findings will aid in optimizing diagnostic accuracy, guiding therapeutic decisions, and enhancing preoperative surgical planning in sinonasal disorders.

Study Design and Duration: This prospective study was conducted at the Department of Radiodiagnosis, Civil Hospital, Ahmedabad, over a period of two years (August 2022 to July 2024). A total of 104 patients with suspected paranasal sinus (PNS) pathologies were included.

Inclusion Criteria: Patients referred for MDCT evaluation of PNS due to symptoms such as nasal obstruction, facial swelling, headache, nasal discharge, fever, or suspected neoplastic lesions were included. Those with chronic sinusitis persisting despite medical therapy were also considered.

Exclusion Criteria: Patients with a history of allergy to iodinated contrast media, facial trauma, pregnancy, or renal dysfunction were excluded to ensure patient safety.

Imaging Protocol: All patients underwent MDCT using a 128-slice GE Revolution Maxima scanner. The scan parameters were as follows:

• Patient position: Supine
• Scan extent: From the hard palate to the frontal sinus
• Scan direction: Caudo-cranial
• Field of view (FOV): 150 mm
• Slice thickness: 0.625 mm
• Tube voltage: 140 kVp
• Tube current: 135 mA
• Multiplanar reconstructions: Coronal and sagittal images

For contrast-enhanced scans, intravenous non-ionic iodinated contrast (Iohexol, 350 mg/mL) was administered at 1 mL/kg at 2 mL/sec using an automated injector. In cases of suspected invasive fungal sinusitis or malignancy, the scanning extent was expanded to include the brain and neck. Additionally, CT angiography was performed in two cases of juvenile nasopharyngeal angiofibroma to assess vascular supply.

Image Interpretation: Scans were analyzed for

• Anatomical variations (e.g., concha bullosa, deviated nasal septum, Haller cells)
• Inflammatory changes (mucosal thickening, polyps, air-fluid levels)
• Neoplastic lesions (benign vs. malignant)
• Bony involvement (erosion, remodeling, destruction)

Findings were correlated with clinical history and histopathology wherever available.

Statistical Analysis: Data were analyzed using SPSS software (Version 23). Descriptive statistics, including mean, standard deviation, frequency, and percentage, were used to summarize findings. Sensitivity and specificity of MDCT in diagnosing various PNS pathologies were calculated using histopathological confirmation as the reference standard.

Ethical Considerations: Informed written consent was obtained from all patients before imaging. Patients were briefed about the procedure, its risks, and benefits. Institutional ethical clearance was obtained before initiating the study.

Demographic Distribution: The age of the patients ranged from 5 to 78 years, with a mean age of 43 years. The majority of cases (60.4%) were observed in patients above 40 years, with the highest incidence in the 41-50 years age group (30.7%). Males were more frequently affected (65.38%) compared to females (34.62%), resulting in a male-to-female ratio of approximately 1.9:1 (Table 1).

Table 1: Age and Gender Distribution of Study Participants

Clinical Presentation: The most common presenting symptoms were nasal obstruction (36.53%), followed by nasal discharge (32.69%) and facial swelling (25%). Headache (22.11%) and fever (15.38%) were also frequently reported, while nasal bleeding was the least common symptom (Table 2).

Table 2: Clinical Presentation of Patients

Anatomical Variations: MDCT revealed anatomical variations in a significant proportion of patients, which could predispose them to sinus diseases. The most frequent variations included deviated nasal septum (43.3%), concha bullosa (30.8%), and Haller cells (21.1%). Other variations, such as Onodi cells and paradoxical middle turbinate, were less common but clinically significant (Figure 1).

Inflammatory Conditions: Inflammatory sinus diseases were the most common findings, observed in 76.9% of cases. Chronic sinusitis was the predominant pathology, affecting 44.2% of patients, followed by sinonasal polyposis (20.2%). Fungal sinusitis was identified in 7.7% of cases, often associated with bony erosions. Mucocele and retention cysts were seen in a smaller subset (Table 3).

Table 3: Inflammatory Conditions Diagnosed on MDCT

Neoplastic Conditions: Neoplastic lesions accounted for 19.2% of cases, with benign tumors being more frequent than malignant ones. Inverted papilloma (7.7%) was the most common benign tumor, whereas squamous cell carcinoma (5.8%) was the most frequently observed malignant tumor. Other rare malignancies included adenoid cystic carcinoma and esthesioneuroblastoma (Figure 2).

Bony Involvement and Extension: Bony involvement was observed in 29.8% of cases, with bone remodeling (17.3%) being more frequent than bone destruction (12.5%). Among neoplastic cases, orbital invasion (5.8%) and intracranial extension (3.8%) were noted, emphasizing the aggressive nature of certain lesions (Table 4).

Table 4: Bony Involvement and Disease Extension

Comparison with Histopathology: Histopathological correlation was available for 60 patients, showing a 90.5% agreement between MDCT findings and final diagnoses. Sensitivity and specificity for diagnosing neoplastic lesions using MDCT were 92.3% and 95.6%, respectively (Table 5).

Table 5: MDCT and Histopathological Correlation

In our study MDCT has very low validity and reliability for fungal sinusitis with only 33.3% sensitivity. While validity and reliability for inflammatory and other infective sinusitis is better with sensitivity of 50% and 81.8% respectively. MDCT can be very much reliable for malignant pathologies of Paranasal sinuses with sensitivity of 100% [Table 6].

Table 6: Validity of MDCT for diagnosing different Paranasal sinus pathologies

Soft tissue window shows soft tissue density lesion involving maxillary sinus extending into the middle meatus through the osteomeatal complex on right side with bony destruction of osteomeatal complex. There is near complete ossification with few hyperdense areas within involving ethmoid, frontal and sphenoid sinuses. On bone window, there is opacification involving all the sinuses on both sides with thinning of involved bony segments.

Image A – Axial soft tissue window image of PNS
Image B – Coronal soft tissue window image of PNS
Image C – Sagittal soft tissue window image of PNS
Image D – Axial bone window image of PNS
Image E – Coronal bone window image of PNS
Image F – Sagittal bone window image of PNS

Multidetector computed tomography (MDCT) has emerged as the imaging modality of choice for evaluating paranasal sinus (PNS) pathologies due to its superior spatial resolution, multiplanar reconstruction capabilities, and ability to differentiate soft tissue, air, and bone structures with high accuracy [1]. This study aimed to assess the role of MDCT in diagnosing various PNS diseases, including inflammatory conditions, anatomical variations, and neoplastic lesions, while also evaluating its validity and reliability in different pathological conditions.

Inflammatory and infective sinus diseases represent the most common PNS pathologies, with chronic sinusitis (44.2%) and sinonasal polyposis (20.2%) being the predominant conditions detected in this study. MDCT demonstrated a 50% sensitivity for diagnosing inflammatory sinusitis and an 81.8% sensitivity for infective sinusitis. Previous studies have shown that MDCT is highly effective in delineating the extent of sinus inflammation, mucosal thickening, and air-fluid levels, making it a valuable tool for evaluating chronic rhinosinusitis and its complications [6]. However, the lower sensitivity observed in our study suggests that MDCT findings must be correlated with clinical and endoscopic assessments for definitive diagnosis [4].

Fungal sinusitis presented diagnostic challenges, with MDCT showing only 33.3% sensitivity for its detection. This is consistent with prior reports indicating that while fungal sinusitis often presents as hyperattenuating foci on MDCT, its differentiation from dense secretions remains difficult [5]. The 100% specificity observed in this study indicates that when MDCT does identify fungal sinusitis, the likelihood of false positives is minimal. However, MRI remains the preferred imaging modality for evaluating soft tissue components of fungal infections [3].

Anatomical variations in the osteomeatal complex and lateral nasal wall play a critical role in the

development of sinonasal diseases. In this study, deviated nasal septum (43.3%), concha bullosa (30.8%), and Haller cells (21.1%) were among the most commonly observed variations. These findings are consistent with previous studies that emphasize the role of anatomical variants in predisposing individuals to sinus drainage obstruction and recurrent infections [2,3]. MDCT is particularly advantageous in preoperative assessment for functional endoscopic sinus surgery (FESS), as it provides a detailed roadmap of anatomical landmarks, reducing intraoperative complications [7].

MDCT demonstrated excellent diagnostic accuracy in detecting sinonasal neoplasms, with 100% sensitivity for malignant lesions. Among neoplastic conditions, inverted papilloma (7.7%) was the most frequently encountered benign tumor, whereas squamous cell carcinoma (5.8%) was the predominant malignant pathology. MDCT effectively differentiated benign from malignant lesions by assessing bony destruction, tumor extension, and enhancement patterns [8]. Previous literature highlights the role of contrast-enhanced MDCT in detecting tumor invasion into adjacent structures such as the orbit, skull base, and intracranial compartment, findings that were also observed in our study [9].

Bony changes were noted in 29.8% of cases, with bone remodeling (17.3%) being more frequent than bone destruction (12.5%). Malignant lesions exhibited aggressive features, including orbital invasion (5.8%) and intracranial extension (3.8%), findings that are crucial for surgical planning and prognostic assessment [10]. The ability of MDCT to assess cortical bone involvement makes it indispensable for differentiating benign lesions with remodeling from aggressive neoplasms causing destructive changes [11].

The high sensitivity and specificity of MDCT for neoplastic conditions affirm its reliability as a primary imaging modality for PNS tumors. However, its limited sensitivity in detecting fungal sinusitis and differentiating inflammatory conditions suggests that supplementary imaging techniques such as MRI and diagnostic nasal endoscopy may be required for comprehensive evaluation [12]. Another limitation of MDCT is its inability to differentiate between chronic inflammatory changes and early neoplastic transformations in cases with overlapping imaging features [13-15].

This study underscores the critical role of MDCT in diagnosing a spectrum of PNS pathologies. While it remains the gold standard for evaluating anatomical variations and neoplastic lesions, its role in diagnosing fungal and inflammatory sinusitis is limited by relatively low sensitivity. A combined approach integrating MDCT with clinical, histopathological, and endoscopic assessments is essential for optimal patient management.

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