Clinical Characteristics Other Than Intralesional Hyperdensity May Increase the Preoperative Diagnostic Accuracy of Maxillary Sinus Fungal Ball

Using the Hounsfield Units Derived From Computed Tomography (CT) Scans to Differentiate Between the Subtypes of Allergic Fungal Rhinosinusitis: A Retrospective Study

Background Allergic fungal sinusitis (AFS) is an inflammatory condition, often diagnosed using computed tomography (CT) scans, where Hounsfield units (HU) serve as a critical metric. However, the diagnostic process can be challenging due to the ambiguous patterns of sinus secretions. This study evaluates whether the HU measurements from preoperative CT scans can reliably differentiate between the subtypes of AFS and other chronic rhinosinusitis (CRS) entities by correlating these values with histopathological findings. Patients and methods A retrospective analysis was conducted on 120 patients with suspected AFS. All patients had undergone surgical endoscopy at the King Saud Medical City, Riyadh, Saudi Arabia, between 2012 and 2022. Radiographic data, including average, maximum, minimum, and standard deviation (SD) of HU values from unenhanced CT scans, were collected and analyzed. We assessed the diagnostic utility of HU metrics using one-way analysis of variance (ANOVA) and receiver operating characteristic (ROC) curve analysis to determine optimal HU thresholds for differentiating sinus opacities. Results Histopathological analysis revealed that 29 (24.2%) cases exhibited non-fungal sinus opacities, 50 (41.7%) displayed sinus fungal balls, and 41 (34.2%) showed allergic fungal mucin. Notably, allergic fungal mucin demonstrated lower heterogeneity and density compared to the other pathologies. Post hoc analysis indicated significant differences in HU maximum values for fungal balls, along with HU average and HU SD values for allergic fungal mucin. ROC curve analysis for fungal balls yielded a high area under the curve (AUC) for HU maximum (AUC=0.868; 95% CI: 0.794-0.923). The optimal HU maximum threshold of 299 provided a sensitivity of 100% and specificity of 71.43% for detecting fungal balls. Allergic fungal mucin showed high AUC values for HU average (AUC=0.979; 95% CI: 0.934-0.996) and HU SD (AUC=0.973; 95% CI: 0.926-0.994). The optimal HU average and HU SD thresholds of 44.0 and 55.6 yielded sensitivities of 90.2% and 100%, and specificities of 100% and 77.1%, respectively. Conclusion This study identifies significant correlations between the HU parameters from paranasal CT scans and the pathological features in AFS. Notably, the HU SD and average values correlate with allergic fungal mucin, while HU maximum value indicates the presence of fungal balls. These results suggest that quantitative CT density assessment can aid in differentiating the pathologies of rhinosinusitis. However, external validation is required, and future studies should focus on diverse populations and establish cut-off points for tailored treatment strategies in suspected fungal sinus disease.

Dental implant as a potential risk factor for maxillary sinus fungus ball

Fungus ball is the most common form of non-invasive fungal sinusitis, and maxillary sinus is the most commonly involved site. Maxillary sinus fungus ball (MFB) accounts for a considerable proportion of unilateral maxillary sinusitis. The prevalence of MFB has recently increased; however, its contributing factors are unclear. This study analyzed the association between MFB and dental implants. One hundred one patients who underwent unilateral maxillary sinus surgery were divided into two groups based on surgical biopsy results: unilateral bacterial sinusitis (UBS, n = 45) and MFB (n = 56). Stratified random sampling of 30 patients from each group was performed to adjust for age. The number of dental implants on maxillary teeth and degree of penetration into the maxillary sinus was radiologically evaluated. The number of patients with dental implants was greater (P = 0.085) and the number of implants was significantly higher (P = 0.031) in the MFB group. Dental implant can be a potential risk factor for MFB development. Therefore, dental implant surgeons should take caution in penetrating the maxillary sinus floor during implant insertion and otolaryngologists should consider the possibility of fungus ball when assessing patients with sinusitis who have dental implants.

Enhanced artificial intelligence-based diagnosis using CBCT with internal denoising: Clinical validation for discrimination of fungal ball, sinusitis, and normal cases in the maxillary sinus

BACKGROUND AND OBJECTIVE

The cone-beam computed tomography (CBCT) provides three-dimensional volumetric imaging of a target with low radiation dose and cost compared with conventional computed tomography, and it is widely used in the detection of paranasal sinus disease. However, it lacks the sensitivity to detect soft tissue lesions owing to reconstruction constraints. Consequently, only physicians with expertise in CBCT reading can distinguish between inherent artifacts or noise and diseases, restricting the use of this imaging modality. The development of artificial intelligence (AI)-based computer-aided diagnosis methods for CBCT to overcome the shortage of experienced physicians has attracted substantial attention. However, advanced AI-based diagnosis addressing intrinsic noise in CBCT has not been devised, discouraging the practical use of AI solutions for CBCT. We introduce the development of AI-based computer-aided diagnosis for CBCT considering the intrinsic imaging noise and evaluate its efficacy and implications.

METHODS

We propose an AI-based computer-aided diagnosis method using CBCT with a denoising module. This module is implemented before diagnosis to reconstruct the internal ground-truth full-dose scan corresponding to an input CBCT image and thereby improve the diagnostic performance. The proposed method is model agnostic and compatible with various existing and future AI-based denoising or diagnosis models.

RESULTS

The external validation results for the unified diagnosis of sinus fungal ball, chronic rhinosinusitis, and normal cases show that the proposed method improves the micro-, macro-average area under the curve, and accuracy by 7.4, 5.6, and 9.6% (from 86.2, 87.0, and 73.4 to 93.6, 92.6, and 83.0%), respectively, compared with a baseline while improving human diagnosis accuracy by 11% (from 71.7 to 83.0%), demonstrating technical differentiation and clinical effectiveness. In addition, the physician's ability to evaluate the AI-derived diagnosis results may be enhanced compared with existing solutions.

CONCLUSION

This pioneering study on AI-based diagnosis using CBCT indicates that denoising can improve diagnostic performance and reader interpretability in images from the sinonasal area, thereby providing a new approach and direction to radiographic image reconstruction regarding the development of AI-based diagnostic solutions. Furthermore, we believe that the performance enhancement will expedite the adoption of automated diagnostic solutions using CBCT, especially in locations with a shortage of skilled clinicians and limited access to high-dose scanning.

Imaging Spectrum of Coronavirus Disease- 2019 Associated Rhino-Orbital-Cerebral Mucormycosis; From Sinonasal Inflammation to Intracranial Involvement

RATIONALE AND OBJECTIVES

Rhino‑Orbital‑Cerebral Mucormycosis (ROCM) is a life-threatening opportunistic fungal infection, which mostly affects immunocompromised patients. There has been a notable rise in the incidence of ROCM during the COVID-19 outbreak. In this study we described imaging characteristics of ROCM in detail, from early sinonasal inflammation to late intracranial involvement.

MATERIALS AND METHODS

In this retrospective study, Computed Tomography (CT) scan and Magnetic Resonance Imaging (MRI) of 48 patients with proven ROCM in biopsy or culture were evaluated. All the patients had a history of COVID-19 infection within the previous three months. The imaging findings were described and the frequency of different parameters was reported.

RESULTS

Paranasal inflammation was detected in all the patients on imaging. The most common involved paranasal sinuses were ethmoid sinuses (97.9%). On diffusionweighted images, restricted diffusion was seen in the paranasal sinuses of 81.1% of the patients. In addition, sinus wall bone involvement was observed in 87.5% of the cases. The most common anatomical sites for extrasinus involvement were the retroantral soft tissue (89.6%) and orbital cavity (87.5%). Dacryocystitis in 50%, optic nerve inflammation in 43.2%, globe involvement in 18.9%, and trigeminal nerve involvement in 16% of the patients were detected. There was extension of inflammation through the cavernous sinuses and alongside the internal carotid arteries in 24% of the patients.

CONCLUSION

Characteristic imaging findings of ROCM not only play a vital role in the early diagnosis of this infection, but they also contribute to the assessment of the extension of inflammation, which is vitally important in surgical planning.

Prevalence and Clinical Implications of Lateral Wall Dehiscence in the Sphenoid Sinus: Sternberg's Canal

Background and Objectives

Sternberg's canal is known to result from incomplete fusion of bony compartments constituting the sphenoid bone during the developmental process. This study aimed to evaluate the prevalence and clinical implications of Sternberg's canal.

Methods

A retrospective review of patients over the age of 18 years who had undergone endoscopic sinus surgery from 2014 to 2019 at a single institution was performed. Patients (n=98) were categorized into those with sphenoid fungal ball (SFB) (n=39), those with primary chronic rhinosinusitis (CRS) (n=39), and controls (n=20) and were evaluated radiologically. A small pit in the lateral wall, located medial to the maxillary division of the trigeminal nerve (V2), in front of the opticocarotid recess was regarded as Sternberg's canal. Children under the age of 12 years (n=39) without any sinus disease were also evaluated to determine the prevalence of Sternberg's canal in the pediatric population.

Results

Patients with SFB showed the highest prevalence of Sternberg's canal (56.4%), followed by those with CRS (20.5%) and controls (10.0%) (p<0.001). Logistic regression revealed that Sternberg's canal was associated with osteitis of the sphenoid wall, and not with age, sex, or sphenoid sinus pathology. Children under the age of 12 years showed a significantly higher prevalence of the defect than adult controls (46.2%, p<0.001).

Conclusion

Sternberg's canal was frequently identified in children under the age of 12 years. Sphenoid sinus pathology was often accompanied by osteitis. However, the presence of the canal alone did not predict skull base involvement in patients with SFB. A comprehensive evaluation should hence be performed if skull base involvement is suspected in such patients. Additionally, other clinical implications of Sternberg's canal should be further evaluated.

Analysis of predisposing factors in unilateral maxillary sinus fungal ball: the predictive role of odontogenic and anatomical factors

BACKGROUND

The pathogenesis of maxillary sinus fungal ball (MSFB) is explained by aerogenic and odontogenic factors. We evaluated the predisposing factors, including intranasal anatomical and dental factors for increased diagnostic accuracy.

METHODOLOGY

In this study, 117 patients who underwent endoscopic sinus surgery for unilateral MSFB were included. Preoperative computed tomography (CT) scans were used to analyze the presence of anatomical variations (anterior and posterior nasal septal deviation (NSD), concha bullosa (CB), infraorbital cell (haller cell), paradoxical middle turbinate, everted uncinate process and MS size). Dental factors including history of dental procedures and findings on CT scans were reviewed.

RESULTS

Anterior and posterior NSD toward non-affected side were significantly associated with the presence of FB. The presence of CB and infraorbital cell was higher in the non-affected side rather than in the lesion side. Compared to non-affected MS, FB-presence MS was shallower and had a larger height to depth ratio. The presence of dental history was significantly higher on FB-presence MS than non-affected MS. In multivariable analysis, posterior NSD toward non-affected side, dental history increased the aOR of MSFB, while the presence of CB and infraorbital cell decreased the aOR of MSFB.

CONCLUSIONS

The occurrence of MSFB seems to be associated with ipsilateral odontogenic factors, followed by anatomic variations including posterior NSD toward non-affected side and absence of CB and infraorbital cell.

High CT Attenuation Values Relative to the Brainstem Predict Fungal Hyphae Within the Sinus

Objectives

There is currently no established objective diagnostic indicator for the differentiation of sinus fungal ball (SFB) from unilateral nonfungal chronic sinusitis (UCRS). This study evaluated whether computed tomography (CT) attenuation values relative to those of the brainstem (relative CT number) are useful for differentiating SFB from UCRS.

Materials and Methods

Consecutive patients who were pathologically diagnosed with SFB or UCRS between 2013 and 2021 were retrospectively identified. The relative CT numbers of region of interest (ROIs) within the sinuses were compared between the two patient groups. Factors with predictive power for differentiating SFBs from UCRSs were identified by uni/multivariable logistic regression analyses.

Results

One hundred and eighty-three patients with unilateral chronic sinusitis were finally analyzed (SFB, 86 cases; UCRS, 97 cases). Regardless of the presence or absence of calcified lesions, the relative CT numbers in SFB were significantly higher than those in UCRS. ROIs showing high relative CT numbers were those where fungal hyphae were present. In the uni/multivariable logistic regression analysis, age (p < 0.001), relative CT number (p < 0.001), and calcification (p = 0.002) had predictive value for distinguishing SFB from UCRS. Within those cases not showing calcification, age (p = 0.004) and relative CT number (p < 0.001) were predictive factors for differentiating SFB from UCRS. A relative CT number >1.5 was significantly associated with SFB (sensitivity, 70%; specificity, 91%), with a significantly larger area under the receiver operating characteristics curve than age.

Conclusions

High relative CT numbers within the sinus are strongly associated with the presence of fungal hyphae, and measurement of relative CT number is a powerful adjunctive diagnostic method for distinguishing between SFB and UCRS.

Clinical Characteristics According to the Radiological Classifications of Maxillary Sinus Fungus Ball

Background and Objectives

The purpose of this study was to classify radiological findings of patients diagnosed with maxillary sinus fungus ball and to analyze the differences in surgical approach methods and postoperative results.

Methods

As a retrospective study, we reviewed the medical records of 221 patients (unilateral in 216: bilateral in 5).

Results

On computed tomography (CT), 49% of the lesions had an irregular surface or a protruding part. There was a significant difference in surgical approach according to pneumatization of the maxillary sinus when middle meatal antrostomy (MMA) was performed alone or combined with MMA and inferior meatal antrostomy (IMA) (p=0.042). Extension of a maxillary sinus lesion caused by fungus ball was not associated with stenosis of the MMA (p=0.328).

Conclusion

Diagnosis of maxillary sinus fungus on CT was associated with irregular lesion surface or a protruding calcification. In patients with fungus ball of the maxillary sinus, the more severe is the maxillary sinus pneumatization, the larger is the extent of IMA needed.

Detection of maxillary sinus fungal ball via 3-D CNN-based artificial intelligence: Fully automated system and clinical validation

Background

This study aims to develop artificial intelligence (AI) system to automatically classify patients with maxillary sinus fungal ball (MFB), chronic rhinosinusitis (CRS), and healthy controls (HCs).

Methods

We collected 512 coronal image sets from ostiomeatal unit computed tomography (OMU CT) performed on subjects who visited a single tertiary hospital. These data included 254 MFB, 128 CRS, and 130 HC subjects and were used for training the proposed AI system. The AI system takes these 1024 sets of half CT images as input and classifies these as MFB, CRS, or HC. To optimize the classification performance, we adopted a 3-D convolutional neural network of ResNet 18. We also collected 64 coronal OMU CT image sets for external validation, including 26 MFB, 18 CRS, and 20 HCs from subjects from another referral hospital. Finally, the performance of the developed AI system was compared with that of the otolaryngology resident physicians.

Results

Classification performance was evaluated using internal 5-fold cross-validation (818 training and 206 internal validation data) and external validation (128 data). The area under the receiver operating characteristic over the internal 5-fold cross-validation and the external validation was 0.96 ±0.006 and 0.97 ±0.006, respectively. The accuracy of the internal 5-fold cross-validation and the external validation was 87.5 ±2.3% and 88.4 ±3.1%, respectively. As a result of performing a classification test on external validation data from six otolaryngology resident physicians, the accuracy was obtained as 84.6 ±11.3%.

Conclusions

This AI system is the first study to classify MFB, CRS, and HC using deep neural networks to the best of our knowledge. The proposed system is fully automatic but performs similarly to or better than otolaryngology resident physicians. Therefore, we believe that in regions where otolaryngology specialists are scarce, the proposed AI will perform sufficiently effective diagnosis on behalf of doctors.

Differences in clinical and imaging presentation of maxillary sinus fungus ball with and without intralesional hyperdensity

Maxillary sinus fungal balls (MSFBs) mostly occur in older individuals and demonstrate female predominance. Early diagnosis is important to avoid treatment delays. Intralesional hyperdensity (IH) indicates the presence of heavy metal deposition within fungal hyphae and has been the most specific characteristic of MSFB on computed tomography (CT). For those without IH on CT, the diagnosis of MSFB remains challenging. This study aimed to characterize clinical presentation of MSFB with and without IH and to study factors contributing to MSFB with no IH formation. We retrospectively identified 588 patients with MSFB. The clinical characteristics and CT findings were reviewed. Patients with unilateral MSFB had a mean age of 57.4 years and demonstrated female predominance (64.63%). The female-to-male ratio was highest at 51–60 years (2.02) and rose to 2.60 in MSFB with IH only. Compared to those with IH, MSFB without IH was significantly more common in males (OR = 2.49), in those with diabetes mellitus (DM) (OR = 1.87), adjacent maxillary odontogenic pathology (OR = 1.75). Complete opacification on CT was less common in MSFB without IH (OR = 0.60). Patients with MSFB without IH were more likely to have DM, no female predominance, adjacent maxillary odontogenic pathology, and partial opacification of the sinus, compared to those with IH. These may be helpful in better understanding of the formation of MSFBs without IH, early identification of them and prevention of post-operative recurrence.

Clinical features in maxillary sinus fungus ball in patients with malignant hematological disease

PURPOSE

Previous studies on fungus balls have primarily focused on immunocompetent patients, and only a few studies have described the clinical characteristics of fungus balls in malignant hematological disease (MHD) patients. Therefore, we compared the clinical features of maxillary sinus fungus ball (MSFB) between immunosuppressive patients with MHD and immunocompetent patients.

METHODS

Twenty patients with MHD and 40 randomly selected immunocompetent patients were enrolled and divided into MHD and non-MHD groups. All patients were diagnosed with MSFB and their clinical features were retrospectively analyzed.

RESULTS

Patients in the MHD group had non-specific clinical symptoms and endoscopic manifestations of MSFB, similar to those in the non-MHD group. On computed tomography (CT), the MHD group showed higher Lund-Mackay scores, lesser single sinus opacifications, more multiple sinus opacifications on the affected side, and more bilateral opacifications compared to the non-MHD group. The MHD group had a lower frequency of central hyper-density and heterogeneous opacifications than the non-MHD group. There were no significant differences between the two groups in terms of the fungal-infected side, lateral sinus wall ratio, sclerosis of the lateral sinus wall, erosion of the inner sinus wall, and nasal septum deviation.

CONCLUSION

The clinical symptoms and endoscopic manifestations of MSFB in patients with MHD were similar to those of immunocompetent patients. However, more atypical signs and wider mucosal inflammation were found on CT scans of MSFB patients with MHD. These results indicate that caution should be executed when excluding the possibility of fungus balls in immunosuppressive patients.

Characteristic features of fungus ball in the maxillary sinus and the location of intralesional calcifications on computed tomographic images: A report of 2 cases

This report presents 2 cases of sinus fungus ball and describes the characteristic radiographic features of fungus ball in the maxillary sinus. Two female patients, aged 62 and 40 years, sought consultations at a dental hospital for the treatment of dental implants and tooth pain, respectively. Panoramic radiography and small field-of-view (FOV) cone-beam computed tomography (CBCT) did not provide detailed information for the radiographic diagnosis of fungus ball due to the limited images of the maxillary sinus. Additional paranasal sinus computed tomographic images showed the characteristic features of fungus ball, such as heterogeneous opacification and intralesional calcification of the maxillary sinus. The calcified materials of the fungus balls were located in the middle and superior regions of the maxillary sinus. It is necessary to use large-FOV CBCT for the detection of calcified materials in the upper maxillary sinus to confirm the diagnosis of fungus ball.

[Unilateral diseases of the maxillary sinus]

Unilateral diseases of the maxillary sinus are among the most common rhinologic diagnoses. The diversity of these diseases can represent a challenge for the treating physician. The spectrum ranges from harmless maxillary sinus cysts that seldom require treatment, to highly aggressive malignant tumors. Special attention should be given to the management of inverted papilloma. These benign tumors are characterized by high recurrence rates and the potential for malignant transformation. The key to minimizing recurrence is precise surgical intervention. Other unilateral maxillary sinus diseases such as the antrochoanal polyp and the fungus ball (aspergilloma) are also discussed in depth.