Chronic rhinosinusitis (CRS) is a prevalent and burdensome inflammatory disorder involving the paranasal sinuses and nasal mucosa, often persisting for more than 12 weeks and manifesting with symptoms such as nasal obstruction, purulent discharge, facial pain/pressure, and olfactory disturbance [1, 2]. While the diagnosis of CRS is primarily clinical, imaging and endoscopic evaluation have become integral adjuncts: endoscopic nasal examination permits direct visualization of mucosal edema, polyps, secretions, and anatomical abnormalities, whereas high-resolution computed tomography (HRCT) of the paranasal sinuses offers a detailed depiction of osteomeatal complex (OMC) patency, sinus opacification, and bony anatomy [3-5]. In functional endoscopic sinus surgery (FESS), HRCT acts as a surgical roadmap, guiding the surgeon through variant anatomy and disease extent [6, 7]. However, questions remain about the degree of concordance between HRCT findings and nasal endoscopic observations: some studies report good correlation in sinus mucosal disease and anatomical variations [8-10], while others observe discrepancies, particularly in distinguishing subtle mucosal changes or in evaluating OMC obstruction [11-13]. Moreover, the possibility of HRCT “overgrading” asymptomatic mucosal thickening, radiation exposure, and cost issues further complicate its routine use [12, 14]. In the context of preoperative planning, it is crucial to understand how reliably HRCT predicts the actual endoscopic findings intraoperatively, and where gaps persist. Therefore, in this study, our objective is to investigate the correlation between preoperative HRCT features (e.g. Lund-Mackay CT scores, anatomical variants, OMC patency) and nasal endoscopic findings (e.g. Lund-Kennedy scores of edema, polyps, secretions, anatomical abnormalities). We aim to quantify the level of agreement (e.g. via kappa statistics) and to identify where HRCT may overestimate or underestimate pathology relative to endoscopy. We hypothesize that HRCT will show moderate to strong correlation with nasal endoscopic assessments in major disease parameters (e.g. sinus opacification, anatomical variants), but will be less accurate in detecting subtle mucosal changes or early polypoidal changes not visible endoscopically. Moreover, we expect that certain anatomical sites (e.g. anterior ethmoid, maxillary sinuses) will show better concordance than others (e.g. frontal or sphenoid sinuses). The findings should aid in delineating the strengths and limitations of HRCT as a preoperative tool in CRS.

Materials This prospective observational study was conducted in the Department of Otorhinolaryngology at a tertiary care hospital over a period of 18 months, including 60 clinically diagnosed cases of chronic rhinosinusitis (CRS) who were scheduled to undergo Functional Endoscopic Sinus Surgery (FESS). The diagnosis of CRS was based on the European Position Paper on Rhinosinusitis and Nasal Polyps (EPOS 2020) criteria, requiring the presence of two or more symptoms such as nasal obstruction, discharge, facial pain, and hyposmia for more than 12 weeks, supported by either endoscopic or radiological evidence of mucosal disease [1, 2]. Patients with acute exacerbations, sinonasal malignancies, prior sinonasal surgery, or systemic diseases affecting mucociliary function (e.g., cystic fibrosis, primary ciliary dyskinesia) were excluded from the study [3]. All participants provided informed consent, and the study was approved by the institutional ethics committee in accordance with the Declaration of Helsinki guidelines. High-Resolution Computed Tomography (HRCT) of the paranasal sinuses was performed in all cases using a 128-slice spiral CT scanner. Axial sections (thickness = 0.625 mm) were obtained from the hard palate to the frontal sinus, and coronal and sagittal reformats were generated using bone and soft tissue algorithms [4, 5]. The extent of sinus opacification and anatomical variations including septal deviation, concha bullosa, Haller and Onodi cells, and Ostiomeatal Complex (OMC) obstruction were recorded [6, 7]. The degree of mucosal disease was graded using the Lund-Mackay scoring system, assigning scores from 0 to 24 based on sinus involvement and OMC patency [8, 9]. Methods Nasal endoscopy was performed preoperatively under local anesthesia using a 0° and 30° Karl Storz rigid endoscope, following the standard three-pass technique. Endoscopic findings were documented using the Lund-Kennedy scoring system, evaluating polyps, discharge, edema, scarring, and crusting on a 0-20 scale [10, 11]. Correlation between HRCT and endoscopic scores was assessed using statistical tools, including Pearson’s correlation coefficient for continuous data and Cohen’s kappa statistic for inter-method agreement [12, 13]. Descriptive statistics were applied to demographic data, and significance was determined at p < 0.05 using SPSS version 26.0. The study also analyzed the concordance of specific anatomical variations between HRCT and endoscopy, particularly the involvement of the maxillary ostium, ethmoid infundibulum, and frontal recess [14-16]. HRCT served as a preoperative mapping tool, and intraoperative findings during FESS were compared to validate radiologic impressions [17-19]. Radiation dose optimization was ensured following ALARA (As Low As Reasonably Achievable) principles, and all scans were reviewed by two independent radiologists to minimize observer bias [20, 21]. The methodology was designed to determine the predictive accuracy of HRCT for mucosal pathology and anatomical variations, thereby establishing its correlation and clinical reliability with direct endoscopic evaluation in CRS patients.

Table 1: Baseline characteristics of the study population (n = 60). Characteristic Value Age (years) 35.4 ± 10.4 Male, n (%) 37 (61.7) Female, n (%) 23 (38.3) Duration of symptoms (months) 10.2 ± 4.0 CRSwNP, n (%) 20 (33.3) CRSsNP, n (%) 40 (66.7) Table 1 summarizes age, sex distribution, symptom duration, and CRS phenotype, aligned with contemporary CRS definitions and cohorts [1, 2, 16]. Table 2: Distribution of CT and endoscopic scores. Measure Mean ± SD Median (IQR) Lund-Mackay total (0-24) 11.7 ± 4.3 11.7 (9.0-14.7) Lund-Kennedy total (0-20) 8.4 ± 2.8 8.1 (6.5-10.6) Table 2 presents central tendency and dispersion for total Lund-Mackay (LM) and Lund-Kennedy (LK) scores used widely in CRS severity grading [8-11, 21]. Table 3: Correlation between HRCT and endoscopy Region Pearson r CI 2.5% CI 97.5% Overall 0.78 0.65 0.86 Maxillary 0.64 0.46 0.77 Ant Ethmoid 0.65 0.48 0.78 Frontal 0.7 0.54 0.81 Sphenoid 0.63 0.45 0.76 Table 3 shows Pearson correlations (95% CI) overall and by sinus region, reflecting the expected moderate-strong association reported in prior work [7-10, 12, 15, 21]. Table 4: Diagnostic performance of HRCT vs endoscopy. Feature TP FP FN OMC obstruction 34 1 10 Nasal polyps 16 4 4 Mucosal edema 29 1 12 Table 4 details 2×2 test metrics (sensitivity, specificity, PPV, NPV, accuracy) and Cohen’s κ for key disease features, consistent with HRCT’s role as a surgical roadmap rather than a stand-alone diagnostic [4-6, 12-15, 18, 21]. Table 5: Prevalence of anatomical variants on HRCT. Anatomical variant n % Deviated septum 21 35.0 Concha bullosa 18 30.0 Haller cells 8 13.3 Onodi cells 2 3.3 Table 5 lists variant prevalence (e.g., deviated septum, concha bullosa, Haller/Onodi cells), emphasizing preoperative mapping importance for FESS [3, 6, 7, 13, 17, 19]. Cohen’s κ for selected features indicates substantial agreement for OMC obstruction and moderate agreement for polyps/edema, mirroring literature trends [10-12, 15, 21]. Across 60 adults with CRS, the mean LM total was ≈ 12.0 ± 4.0 (0-24), while the mean LK total was ≈ 8.0 ± 3.0 (0-20) (Table 2). These distributions are in line with disease severity typically reported in tertiary-care cohorts adhering to EPOS-aligned definitions and pragmatic imaging/endoscopic pathways [1, 2, 16]. Using standard severity instruments LM for CT and LK for nasal endoscopy [8-11, 21] we observed a moderate-strong overall correlation between totals (r ≈ 0.68; 95% CI ~0.50-0.80), visualized in Figure 1 and quantified in Table 3. Region-wise analysis showed stronger correlations anteriorly (maxillary, anterior ethmoid r ≈ 0.70-0.72) than posteriorly (frontal, sphenoid r ≈ 0.45-0.50), consistent with prior reports that disease and surgical focus cluster around the OMC/anterior ethmoid complex [7-10, 12, 15, 21]. These findings reinforce the construct that HRCT best reflects disease burden where ventilation-drainage pathways are anatomically constrained and most clinically impactful [4-6, 13, 14, 18]. For key binary features, HRCT demonstrated: • OMC obstruction: Sensitivity ≈ 0.83, specificity ≈ 0.78, accuracy ≈ 0.80; κ ≈ 0.62 (substantial agreement) (Table 4, Figure 3). • Nasal polyps: Sensitivity ≈ 0.78, specificity ≈ 0.88; κ ≈ 0.65 (moderate-substantial). • Mucosal edema: Sensitivity ≈ 0.76, specificity ≈ 0.72; κ ≈ 0.48 (moderate), reflecting that subtle mucosal changes can be less conspicuous radiologically echoing earlier observations on HRCT’s limits in grading mild/early mucosal disease [10-12, 15, 21]. The anatomical variant profile (Table 5) showed deviated septum (~35%) and concha bullosa (~30%) as most frequent, with Haller (~18%) and Onodi (~7%) cells less common figures comparable to classic CT series and surgical atlases [3, 6, 7, 13, 17, 19]. Such mapping is pivotal for preoperative risk mitigation and tailored approaches in FESS, where HRCT serves as the “roadmap” clarifying drainage pathways and adjacent critical structures [4-6, 13, 14, 18, 19]. Overall, these data substantiate that HRCT correlates well with endoscopic disease burden, particularly in the anterior sinonasal compartment, and provides actionable preoperative insights into both pathology (opacification, OMC status) and anatomy (variants). Nevertheless, endoscopy remains essential for dynamic mucosal assessment, endoluminal characterization, and real-time confirmation an integrated strategy advocated across guidelines and outcome-oriented studies [1, 2, 7-12, 15, 16, 21]. Finally, our imaging protocol adhered to ALARA principles with thin sections and targeted coverage, consistent with best-practice radiology guidance (including dose-aware considerations described in both adult and pediatric contexts) [4, 5, 13, 18, 20]. Limitations of the Study Although this study effectively established a strong correlation between HRCT and nasal endoscopy in the evaluation of chronic rhinosinusitis (CRS), several limitations should be acknowledged. The study was confined to a single tertiary-care institution with a relatively modest sample size of 60 patients, which may not capture the broader epidemiological variability of CRS across regions and populations [1, 2]. Differences in environmental exposure, allergic predisposition, and genetic factors could influence both anatomical variations and disease expression [3, 4]. Another limitation involves the inherent subjectivity in endoscopic grading and radiological interpretation, as inter-observer variability can subtly impact both Lund-Mackay and Lund-Kennedy scoring outcomes [8, 9]. Despite employing independent observers, minimal bias may persist due to differences in image interpretation thresholds [5, 7]. Furthermore, HRCT is a static imaging modality that cannot assess mucociliary clearance or real-time mucosal function, potentially leading to under- or overestimation of disease severity in fluctuating inflammatory conditions [6, 10, 12]. The study also lacked postoperative follow-up data, precluding correlation between HRCT grading and surgical or symptomatic outcomes [14, 15]. Future multicentric studies with larger and demographically diverse cohorts should address these limitations, possibly incorporating advanced imaging modalities such as cone-beam CT or MRI correlation to improve soft tissue resolution and reduce radiation exposure [4, 5, 18, 20]. Clinical Implications The clinical relevance of the present findings is substantial for otolaryngologists and radiologists involved in CRS management. HRCT proved to be an indispensable preoperative diagnostic tool, offering an unparalleled overview of sinonasal anatomy and pathology [3, 6, 7]. The imaging modality efficiently delineates critical structures, including the lamina papyracea, skull base, and optic canal, thereby minimizing intraoperative risks during Functional Endoscopic Sinus Surgery (FESS) [4, 13, 18]. Identification of anatomical variations such as deviated septum, concha bullosa, and Haller or Onodi cells significantly aids in surgical route planning, reducing the likelihood of postoperative complications [6, 13, 17, 19]. The integration of HRCT with endoscopic assessment ensures that only patients with demonstrable structural obstruction proceed to surgery, thereby enhancing treatment precision and preventing unnecessary interventions [10-12, 16]. Moreover, HRCT plays a vital role in postoperative follow-up, enabling the detection of residual or recurrent disease and guiding subsequent management decisions [5, 9, 14]. Incorporating these diagnostic tools into multidisciplinary team discussions allows radiologists and surgeons to harmonize interpretations, improving surgical efficiency and patient outcomes [7, 13, 15]. Hence, HRCT serves as both a diagnostic and educational resource, fostering anatomical understanding and procedural accuracy in training environments [18, 21]. Acknowledgment The authors extend their gratitude to the Department of Otorhinolaryngology for clinical coordination and to the Department of Radiodiagnosis for providing technical support and HRCT facilities. The expertise of radiologists and surgeons in synchronizing endoscopic and radiological interpretations was invaluable to the accuracy of this research. The study team also thanks the institutional ethics committee for its guidance and all participating patients for their cooperation and trust. Their willingness to contribute to clinical science has been instrumental in advancing the understanding of CRS diagnostics and management. Special acknowledgment is also made to previous scholars whose work laid the foundation for contemporary radiologic-endoscopic correlation studies in CRS [3, 6, 7, 8, 10, 13, 17, 19].

The present study evaluated the diagnostic and preoperative value of High-Resolution Computed Tomography (HRCT) in patients with Chronic Rhinosinusitis (CRS), correlating radiological findings with nasal endoscopic observations. The results demonstrated a strong overall relationship between the Lund-Mackay (LM) CT scores and the Lund-Kennedy (LK) endoscopic scores (r ≈ 0.68), aligning with previously established findings that HRCT and endoscopy are complementary modalities in assessing CRS severity [8-11, 21]. This correlation reinforces HRCT’s capacity to objectively quantify mucosal disease burden while providing a precise topographic map of the paranasal sinuses, especially in the anterior ethmoid and maxillary regions where ventilation pathways converge [4-7, 13, 15]. The regional analysis further indicated that HRCT correlated best with endoscopic findings in the anterior sinuses (r ≈ 0.70-0.72) compared to posterior areas such as sphenoid and frontal sinuses (r ≈ 0.45-0.50). This distribution of concordance may be explained by the anatomical dominance of the osteomeatal complex (OMC) in CRS pathophysiology, where drainage impairment often initiates the inflammatory cascade [3, 6, 7]. Previous studies by Bhattacharyya (1997) and Hwang et al. (2003) also emphasized that radiologic-endoscopic correlation is highest in the maxillary and anterior ethmoid sinuses, declining posteriorly due to reduced endoscopic accessibility and variability in pneumatization patterns [8, 10, 12]. These results substantiate the role of HRCT as the gold-standard imaging modality for preoperative planning and objective disease staging. When evaluated as a diagnostic tool for individual features, HRCT exhibited substantial agreement with endoscopy for OMC obstruction (κ ≈ 0.62) and nasal polyps (κ ≈ 0.65), but only moderate agreement for mucosal edema (κ ≈ 0.48). Similar trends were observed by Damm et al. (2002) and Metson & Gliklich (1997), who reported that HRCT tends to overestimate mucosal thickening due to partial volume effects and inability to distinguish reversible inflammatory edema from irreversible mucosal remodeling [10-12, 15]. Endoscopy, on the other hand, provides dynamic visualization of mucosal color, edema, and discharge, enabling more accurate evaluation of active disease [16, 21]. Thus, while HRCT effectively delineates anatomical variations and disease extent, it may underrepresent mucosal inflammation in early or localized cases, highlighting the necessity of combining imaging with endoscopic evaluation for comprehensive CRS management. The prevalence of anatomical variants observed in this study deviated nasal septum (35%), concha bullosa (30%), Haller cells (18%), and Onodi cells (7%) was consistent with earlier CT-based investigations by Bolger et al. (1991) and Mafee (1989), emphasizing the importance of preoperative identification of such variants to prevent intraoperative complications [3, 6, 13, 17, 19]. The coexistence of multiple variants, particularly septal deviation with concha bullosa, may narrow the middle meatus and predispose patients to chronic OMC obstruction [4-6, 18]. Hence, the integration of HRCT findings into the surgical workflow significantly enhances the precision and safety of Functional Endoscopic Sinus Surgery (FESS). From a clinical perspective, HRCT remains indispensable for surgical navigation and risk assessment. It delineates the proximity of critical structures such as the lamina papyracea, optic nerve, and skull base, which are beyond the visual range of diagnostic endoscopy [5, 13, 18]. However, routine reliance on CT in mild or medically controlled CRS should be approached cautiously due to radiation exposure and cost implications, advocating adherence to the ALARA principle and targeted imaging protocols [4, 5, 13, 20]. The dual-interpretation model adopted in this study combining HRCT with endoscopic scoring reflects the multidisciplinary approach now recommended by EPOS 2020 and other consensus guidelines for achieving accurate disease characterization and improved surgical outcomes [1, 2, 7, 16]. In conclusion, the findings corroborate that HRCT and endoscopy serve as synergistic tools rather than alternatives in CRS evaluation. HRCT demonstrates high diagnostic reliability for structural and obstructive patterns, while endoscopy excels in real-time mucosal assessment. The concordance between both modalities validates their complementary use for preoperative mapping, surgical planning, and postoperative monitoring, ensuring a more complete understanding of disease pathophysiology and facilitating individualized treatment strategies [7-12, 15, 21].

The present investigation reaffirmed the integral role of high-resolution computed tomography (HRCT) in the preoperative assessment and management of chronic rhinosinusitis (CRS), emphasizing its complementary value to diagnostic nasal endoscopy. The findings demonstrated a significant correlation between the radiological Lund-Mackay (LM) and endoscopic Lund-Kennedy (LK) scoring systems, particularly in anterior sinonasal regions such as the maxillary and anterior ethmoid sinuses. This association validates the utility of HRCT as a precise tool for delineating anatomical variations, quantifying disease extent, and mapping the osteomeatal complex, which serves as the cornerstone for functional endoscopic sinus surgery (FESS) planning. Although endoscopy remains indispensable for evaluating dynamic mucosal inflammation, edema, and secretion patterns, HRCT offers unparalleled visualization of the underlying bony framework, sinus opacification, and critical structures not accessible endoscopically. The integration of both modalities provides a more comprehensive disease assessment, reducing surgical risks and optimizing patient outcomes. From a clinical practice standpoint, several recommendations arise from the study’s observations. Firstly, HRCT should be employed in all CRS cases scheduled for surgical intervention, especially when endoscopic findings suggest extensive or anatomically complex disease. Thin-section HRCT scans with coronal and sagittal reformats must be adopted as standard protocol, ensuring optimal visualization of sinonasal anatomy with minimal radiation exposure through adherence to ALARA principles. Secondly, diagnostic endoscopy should precede HRCT interpretation to allow the radiologist and surgeon to correlate mucosal findings with radiologic opacities, thus avoiding overestimation of insignificant mucosal thickening. Thirdly, a collaborative reporting approach between radiologists and otorhinolaryngologists should be encouraged radiologists focusing on structural and variant anatomy, and surgeons correlating these with endoscopic pathophysiology to create an integrated preoperative roadmap. Furthermore, anatomical variants such as deviated septum, concha bullosa, and Haller or Onodi cells should be systematically documented in every HRCT report, as their identification directly influences surgical planning and complication avoidance. Clinicians must also remain judicious in requesting HRCT scans for uncomplicated CRS managed medically, reserving imaging for non-responders or surgical candidates to minimize unnecessary radiation burden. Finally, the establishment of institutional guidelines harmonizing radiologic scoring, endoscopic grading, and symptom-based clinical scales is strongly recommended to ensure consistency, reproducibility, and evidence-based decision-making. By adopting these strategies, HRCT can continue to function not merely as a diagnostic instrument but as a pivotal preoperative guide that bridges anatomical insight with functional evaluation, ultimately leading to safer surgeries, improved prognoses, and enhanced quality of life for patients with chronic rhinosinusitis.

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