MR Findings of Fungus Ball: Significance of High Signal Intensity on T1-Weighted Images

Natural Course of the Maxillary Sinus Fungus Ball: Results From Seoul National University Hospital Healthcare Center

OBJECTIVES

The frequency of paranasal sinus fungus balls, a common form of rhinosinusitis, has increased. Although treatment and causative factors have been well investigated, the evolving nature of the fungal balls remains unelucidated. This study aimed to investigate and analyze the changing patterns of fungus balls.

METHODS

This retrospective study analyzed data from 35 participants selected from a pool of 41,497 patients who underwent brain magnetic resonance imaging (MRI) at a large health care center. The extent of the fungus balls was evaluated by grading them from 1 to 4 based on the MR images. The changing process of the fungus ball was analyzed based on demographics, interval between the MRI scans, comorbidities, and specific dental interventions.

RESULTS

The fungus ball grades showed significant progression over time. In the analysis of 29 sinuses with initially low-grade (grades 0, 1, and 2) fungus balls, 15 sinuses showed a grade change <2 (no/minimal change group), whereas 14 sinuses showed grade changes of ≥2 (substantial change group). Intergroup comparison showed that only the interval between the initial and final MRI scans differed significantly (p = 0.008). However, factors, such as age, sex, comorbidities, and history of dental procedures, did not differ significantly between the two groups.

CONCLUSION

This study shows the extent of change in fungus balls, primarily over time. These results offer critical insights into the natural course and progression of the maxillary sinus fungus ball.

LEVEL OF EVIDENCE

4 Laryngoscope, 135:1315-1320, 2025.

Imaging Findings, Complications, and Mimics after Common and Advanced Dental Procedures

Various new dental treatment methods have been introduced in dental clinics, and many new materials have been used in recent years for dental treatments. Dentistry is divided into several specialties, each offering unique treatments, such as endodontics, implantology, oral surgery, and orthodontics. CT and MR images after dental treatment reveal a variety of hard- and soft-tissue changes and dental materials, which often cause image artifacts. Familiarity with posttreatment changes and dental materials is crucial to avoid misinterpretation of image artifacts as true pathologic features, identify complications, and evaluate for recurrent disease. It also is necessary to be aware of conditions that mimic posttreatment changes and know how to differentiate them at imaging. The authors focus on the imaging of expected and unexpected post-dental treatment changes and characteristics of dental materials on CT and MR images in the head and neck region. The article is divided into five sections: (a) imaging after dental implant treatment, (b) imaging after oral surgery, (c) imaging after endodontic treatment, (d) imaging after orthodontic treatment, and (e) imaging effects of dental treatments. Strategies are provided for distinguishing true pathologic features from posttreatment changes, and the importance of understanding dental procedures, the materials used, and their appearances at radiologic imaging is highlighted. Ultimately, this knowledge can enhance radiologists' ability to interpret complex posttreatment imaging findings, improve diagnostic accuracy, and facilitate effective treatment planning for patients with a history of dental procedures. ©RSNA, 2025 Supplemental material is available for this article.

Value of MRI signal intensity in evaluation of allergic fungal rhinosinusitis compared with CT Hounsfield units: Retrospective study

"Allergic fungal sinusitis (AFS)" is typically diagnosed using radiologic images like computed tomography (CT) scans and magnetic resonance imaging (MRI), with the "Hounsfield unit (HU)" in CT scans and T2-weighted images (T2WI) in MRI serving as reliable objective parameters. However, diagnosing AFS might be difficult because of possible signal changes and densities caused by variations in the secretion concentration in the sinus. Few studies have compared the diagnostic performance of MRI and CT scans. This study aimed to investigate the value of MRI signal intensity in evaluating AFS compared with CT HUs. This retrospective study included 111 patients with pathologically confirmed AFS who underwent CT imaging followed by MRI evaluation at King Saud Medical City, Riyadh, Saudi Arabia, from January 2012 to December 2022. Radiographic densities of sinus opacities on CT scan, including the mean HU values, and MRI findings, including signal voids on T1-weighted images and T2WI, were gathered and analyzed. To determine the efficacy of these radiographic characteristics in predicting the disease and the best cutoff value, we employed receiver operator characteristic curves. The mean age was 31.9 ± 15.6 years, and most patients were 74 females (66.7%). The main symptom was nasal obstruction in 73 patients (65.8%). In comparison, between HU and signal void on T2WI, there was moderate predictive performance [area under the curve: 0.856, P = .001]. An ideal HU cutoff value of 69.50 HU was obtained with a sensitivity of 100% and a specificity of 44.7%. However, the receiver operator characteristic for T1-weighted images could not be plotted, as no signal was avoided to predict AFS and it was not statistically significant (area under the curve: 0.566; P = .287). The study found a CT HU of 69.5 can predict MRI T2WI signal values with a void signal, aiding in diagnostic workup and evaluation for AFS.

Advanced imaging of head and neck infections

When head and neck infection is suspected, appropriate imaging contributes to treatment decisions and prognosis. While contrast-enhanced CT is the standard imaging modality for evaluating head and neck infections, MRI can better characterize the skull base, intracranial involvement, and osteomyelitis, implying that these are complementary techniques for a comprehensive assessment. Both CT and MRI are useful in the evaluation of abscesses and thrombophlebitis, while MRI is especially useful in the evaluation of intracranial inflammatory spread/abscess formation, differentiation of abscess from other conditions, evaluation of the presence and activity of inflammation and osteomyelitis, evaluation of mastoid extension in middle ear cholesteatoma, and evaluation of facial neuritis and labyrinthitis. Apparent diffusion coefficient derived from diffusion-weighted imaging is useful for differential diagnosis and treatment response of head and neck infections in various anatomical sites. Dynamic contrast-enhanced MRI perfusion may be useful in assessing the activity of skull base osteomyelitis. MR bone imaging may be of additional value in evaluating bony structures of the skull base and jaw. Dual-energy CT is helpful in reducing metal artifacts, evaluating deep neck abscess, and detecting salivary stones. Subtraction CT techniques are used to detect progressive bone-destructive changes and to reduce dental amalgam artifacts. This article provides a region-based approach to the imaging evaluation of head and neck infections, using both conventional and advanced imaging techniques.

[Peculiarities of fungal and bacterial microorganisms persistence in the structure of fungal balls of paranasal sinuses]

OBJECTIVE

To compare the data of pathomorphological and microbiological examination of fungal balls removed at paranasal sinuses endoscopic surgery.

MATERIAL AND METHODS

A total of 148 samples were obtained from patients histologically diagnosed with fungal balls. Microscopic evaluation of the specimens stained according to the Gram method, Gomori-Grocott method and PAS-reaction method, revealed phase changes in the fungal balls conditioned by their different life cycles: the areas of young, mature and degenerating mycelium were detected. Degeneration lead to detritus formation. Detritus areas contained accumulated bacterial colonies. The cultural study of the fungal balls removed from paranasal sinuses, showed fungi growth in 17.6% of cases, while the pathomorphological study confirmed presence of fungi in every investigated sample. Aerobic and anaerobic microbiota of the sinuses contents was represented by multi-agent bacterial and fungal-bacterial associations. Statistical analysis of contingency between culture-positive rate of fungi and different bacteria detected in clinical samples from fungal balls revealed inhibitory influence of Pseudomonas aeruginosa on fungi growth, which might be a reasons of their low isolation rate. Supposedly in some cases the fungal balls consisted of dead fungi, or the sampling was done in the area of the fungal balls degeneration, which might also account for the low sensibility of the cultural method.

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.

[Analysis of clinical characteristics of fungal ball in unilateral maxillary sinus]

Objective:The aim of this study is to investigate the pathological characteristics of unilateralmaxillary sinus fungus ball（UMFB） in order to improve the accuracy of clinical diagnosis. Methods:A total of 86 patients with unilateral maxillary sinus lesions who underwent nasal endoscopic surgery in Qilu Hospital of Shandong University（Qingdao） from January 2017 to June 2019 were included. Those patients were confirmed UMFB or unilateral chronic maxillary sinusitis（UCMS） by pathology. The characteristics including age, sex, diabetes mellitus or no, CT features of the diseased maxillary sinus and GOSS osteitis score of the posterolateral wall of the maxillary sinus were analyzed, and the differences between the two groups were compared. CT features include: ①intralesional hyperdensity（calcification）; ②maxillary sinus full haziness with or without mass effect; ③the irregular lobulated protruding lesion（fuzzy appearance） or smooth. Chi-square, independent sample t test and Mann-Whitney U test were performed. Logistic regression analysis and receiver operating Characteristic（ROC） curve analysis were used to find the best cutoff value for UMFB diagnosis. Results:Among the 86 cases of unilateral maxillary sinus lesions, 62 cases were UMFB, which accounted for 72.1%, and 24 cases were UCMS, which accounted for 27.9%. UMFB usually occurs in middle-aged and elderly patients, and there are more females than males. There was no statistical difference between the two groups with or without diabetes. In terms of CT characteristics of paranasal sinuses, intergroup comparison and binary Logistic regression analysis, intralesional hyperdensity, maxillary sinus full haziness with mass effect, the irregular lobulated protruding lesion（fuzzy appearance） were significant predictors of MFB（all P<0.05）. The score of osteitis in UMFB was significantly higher than that in UCMS（P<0.001）. ROC curve analysis showed that when the cutoff value was more than 3.5（the area under the curve was 0.824）, the corresponding sensitivity and specificity were 0.516 and 0.958, respectively. Conclusion:The age, gender, CT characteristics and maxillary sinus osteitis score can distinguish UMFB from unilateral maxillary sinus chronic inflammation, and improve the accuracy of clinical diagnosis.

Hypointense head and neck lesions on T2-weighted images: correlation with histopathologic findings

PURPOSE

On T2-weighted images, most solid lesions exhibit nonspecific intermediate signal intensity, whereas most cystic lesions exhibit marked hyperintensity. In contrast, on T2-weighted images, a relatively small number of lesions exhibit hypointensity. This review aimed to differentiate, according to the histopathologic findings, head and neck lesions showing hypointensity on T2-weighted images.

METHODS

In this review article, hypointense head and neck lesions on T2-weighted images are classified into the following nine categories: calcified or osseous lesions, granulomatous lesions, fibrous lesions, mucous- or proteincontaining lesions, hemosiderin-containing lesions, melanin-containing lesions, thyroglobulin-containing lesions, rapid blood flow, and air-filled spaces.

CONCLUSION

Knowledge regarding hypointense head and neck lesions on T2-weighted images allows radiologists to make accurate differential diagnoses. Key points • Hypointense head and neck lesions on T2-weighted images include calcified or osseous lesions, granulomatous lesions, fibrous lesions, mucous- or protein-containing lesions, hemosiderin-containing lesions, melanin-containing lesions, thyroglobulin-containing lesions, rapid blood flow, and air-filled spaces. • Radiologists should recognize the hypointense head and neck lesions on T2-weighted images for the final correct diagnosis, resulting in appropriate patient management.

Imaging of Paranasal Sinus Infections in Children: A Review

Paranasal sinuses (PNS) infections are common in children. They may cause common and well-known complications, but also, unusual and potentially devastating complications. Diagnosing PNS infections and complications in children requires knowledge of the unique anatomy of the nasal cavity and the PNS. In fetal life, nasal mucosa evaginations into the lateral nasal walls initiate the development of the PNS. The PNS continue to develop after birth and complete their maturation and pneumatization at different ages during childhood which makes the pattern of PNS infections determined by patient age. Complications are caused by direct spread of the infection to the orbit, face, intracranial or osseous structures or hematogenous spread of the infection to the intracranial structures. Emergent imaging studies are often necessary in the evaluation of the complications in pediatric patients when the symptoms persist for 10 days and/or if there is evidence of intracranial or orbital complications. In addition, immunocompromised children are especially vulnerable to developing unusual complications. Computed tomography (CT) is excellent for determining whether there is intraorbital extension of PNS disease. However, when the infection approaches the orbital apex, a magnetic resonance imaging (MRI) study with contrast is necessary to assess spread into the cavernous sinus and the intracranial compartment. The goal of this manuscript is to review and characterize imaging findings of PNS infections using CT and MRI allowing determination of the extent of PNS infections and their common and unusual complications in children. In addition, a summary of the development of the normal PNS is provided.