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Objectives. To evaluate the diagnostic performance of MRI compared with CT in differentiating neoplastic from infectious/inflammatory causes of complete unilateral maxillary sinus opacification (UMSO). Although MRI is increasingly used, no studies validate its utility compared to CT or nasal endoscopy in this context. Methods. A retrospective analysis of 49 patients presenting with complete UMSO to a tertiary referral centre was performed, investigated with both CT and MRI. Two head and neck radiologists independently reviewed each imaging modality and recorded both a final diagnosis and Likert-scale diagnostic certainty score. A consensus radiological diagnosis was determined, stratified into potentially neoplastic or infectious/inflammatory aetiology, and compared with nasal endoscopy and final diagnosis. Diagnostic performance and interoperator agreement for predicting neoplasia were calculated. Results. Both CT and MRI demonstrated high sensitivity and negative predictive value for neoplasm, although MRI was more specific (79%; 95% CI: 60–92%) than CT (14%; 95% CI: 4–32%), with a higher positive predictive value. MRI was more accurate (88%; 95% CI: 75–95%) than CT (49%; 95% CI: 34–64%) in diagnosing neoplasia. MRI had significantly higher diagnostic certainty Likert scores than CT ( p < 0.0001 for both observers). Interobserver agreement was fair for CT (kappa coefficient = 0.327) and excellent for MRI (kappa coefficient = 0.918). Conclusions. MRI is more specific than CT in characterising UMSO, with greater diagnostic certainty and reproducibility. The additive diagnostic value of MRI complements CT, potentially reducing diagnostic delays in some cases and the need for diagnostic endoscopic sinus surgery in others. We recommend MRI incorporation into the diagnostic pathway for patients with UMSO.

Introduction and Objectives: Stone formers often have a chronic exposure to significant quantities of ionising radiation from radiological investigations and interventions. Predicting radiation exposure would allow the clinician to quantify expected cumulative radiation and find strategies to minimise exposure. We evaluated radiation exposure during ureteroscopy and laser lithotripsy (URS + LL) for a single stone episode and correlated the results to stone characteristics. Method: Data was collected retrospectively for all patients undergoing URS + LL in our institution over a 1 year period. Patients with multiple stones, staghorn stones or incomplete stone clearance were excluded to simplify the analysis. Patient characteristics, fluoroscopy data and stone characteristics were recorded. Results: We included 302 consecutive patients in the study. The majority of stones were located in the renal calyces/pelvis (54%) with the rest located in the upper (18%), middle (13%) and lower ureter (15%). Mean stone diameter was 9.9 mm (range 4–30 mm). Mean radiation exposure time during URS + LL was 44 s (range 12–119 s) with a mean total radiation exposure of 7.5 milligray (mGy; range 1.2–29.7 mGy). Renal stones were associated with 27% higher radiation exposure compared to ureteral stones (8.3 vs. 6.7 mGy; p = 0.02). There was a positive correlation between stone diameter and radiation exposure (Spearman’s correlation coefficient ρ = 0.28; p < 0.001). Stones with diameter greater than 10 mm were associated with 37% higher radiation exposure compared to smaller stones (9.1 vs. 6.6 mGy; p < 0.001). Conclusion: There is a direct correlation between stone burden, as well as location, and radiation exposure during URS + LL. Clinicians should consider strategies to reduce total radiation exposure in recurrent stone formers at risk of high radiation exposure by limiting screening time, using pulsed rather than continuous fluoroscopy, management with primary URS + LL, or using ultrasound guidance.

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