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ORIGINAL ARTICLE
Year : 2021  |  Volume : 24  |  Issue : 4  |  Page : 165-171

Incidental sinus findings in brain MRI for suspected intracranial disease


1 Department of Radiology, Delta State University Teaching Hospital, Oghara, Nigeria
2 Department of Surgery, Delta State University Teaching Hospital, Oghara, Nigeria

Date of Submission28-May-2020
Date of Decision31-Aug-2020
Date of Acceptance28-Dec-2020
Date of Web Publication11-Feb-2022

Correspondence Address:
Dr. Joyce Ekeme Ikubor
Department of Radiology, Delta State University Teaching Hospital, Oghara
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/smj.smj_59_20

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  Abstract 


Introduction: The incidental finding of a paranasal sinus (PNS) abnormality on imaging may lead to early detection of sinus pathologies. Brain magnetic resonance imaging (MRI) is a valuable tool for evaluation of the PNSs. Objectives: The objectives were to determine the prevalence, site, and type of abnormalities in the PNSs of a Nigerian population who had brain MRI for suspected intracranial disease and unrelated sinus disease. Materials and Methods: A cross-sectional design was adopted for this study. Radiology request forms, images, and reports of consecutive patients referred for brain MRI for suspected intracranial disease from January 2018 to December 2019 were studied. Abnormalities detected were complete mucosal opacification, mucosal thickening, collection with air–fluid level, and retention cyst/polyp. Statistical Analysis Used: Data were analyzed using Statistical Package for the Social Sciences for Windows version 22.0 (SPSS Inc. Chicago, IL, USA). Results: Four hundred and seventy-nine patients were referred for brain MRI between January 2018 and December 2019. The prevalence of sinus abnormality detected incidentally was 26.7%. The maxillary sinus was the most frequently involved sinus. Fluid collection with air–fluid level was the most common abnormality. There was no significant relationship between the sinus abnormalities with age and sex. Conclusions: The prevalence rate of abnormal sinus findings on brain MRI is 26.7% in this study, buttressing that morphological changes in the PNSs are frequently encountered incidentally on imaging; hence, there is a need to obtain a relevant history of sinus pathology from patients undergoing brain imaging to aid prompt diagnosis of subclinical sinus disease and achieve optimal therapeutic outcomes.

Keywords: Brain magnetic resonance imaging, intracranial disease, paranasal sinuses


How to cite this article:
Ikubor JE, Okolugbo NE, Ogholoh OD, Kogha N, Bemigho-Odonmeta AP. Incidental sinus findings in brain MRI for suspected intracranial disease. Sahel Med J 2021;24:165-71

How to cite this URL:
Ikubor JE, Okolugbo NE, Ogholoh OD, Kogha N, Bemigho-Odonmeta AP. Incidental sinus findings in brain MRI for suspected intracranial disease. Sahel Med J [serial online] 2021 [cited 2022 May 22];24:165-71. Available from: https://www.smjonline.org/text.asp?2021/24/4/165/337490




  Introduction Top


Magnetic resonance imaging (MRI) is a valuable tool for evaluation of the paranasal sinuses (PNSs) aside from using other imaging modalities such as plain radiography and computed tomography (CT).[1] MRI is the imaging modality of choice for evaluating the PNSs because of its excellent soft-tissue characterization and inherent ability to delineate mucosal abnormalities.[2],[3] It also has the advantages of multiplanar capability and does not utilize ionizing radiation. MRI is a noninvasive imaging modality with ability to adequately demonstrate a wide range of PNS abnormalities.[4] Of particular note is the superiority of MRI in the detection of sinus mucosal abnormalities when compared with CT.[1],[5] However, CT which is complementary to MRI is best in detecting bony abnormalities and calcifications.[6]

Prevalence rates of incidental sinus abnormality on cranial MRI range from 31.7% to 58.2%.[2],[7] Opacification of the sinuses, mucosal thickening, polyps, and retention cysts are some of the most common incidental findings in the PNSs.[6] The maxillary and ethmoidal sinuses are more commonly involved in sinus pathologies.[4],[7]

The incidental finding of a PNS abnormality on imaging can pose a dilemma to the clinician whether to ignore it or to institute a treatment strategy.[8] It has been postulated that asymptomatic incidental mucosal abnormalities of the PNS may be a pointer to the presence of the early pathologic process of allergic rhinosinusitis before its progression through the course of the disease where it presents classically with symptoms.[7],[9]

Hopefully, early detection of allergic rhinosinusitis at its asymptomatic stage will provide better therapeutic outcomes derived by instituting a more efficient medical treatment plan, creation of early awareness, and provision of prompt patient's education on avoidance of allergens that can prevent the disease manifestation to its full-fledged state. On the other hand, some have postulated that treatment should not be instituted for incidental sinus findings on brain imaging for indications other than sinus disease.[10],[11]

Most importantly, it is advocated that incidental sinus imaging findings need to be correlated with clinical findings before diagnosing rhinosinusitis.[12] A significant correlation is noticed between MRI findings and patients' symptomatology;[13] however, Wani et al. did not find any relationship between incidental abnormalities of the PNSs detected on MRI scan with the clinical symptoms.[12]

The purpose of this study is to determine the prevalence, site, and type of abnormalities in the PNSs in a Nigerian population undergoing brain MRI scans for suspected intracranial disease and unrelated sinus disease.


  Materials and Methods Top


This was a cross-sectional study in the Radiology Department of the Delta State University Teaching Hospital, Oghara, in which radiology request forms, images, and reports of patients referred for MRI scan of the brain for suspected intracranial disease from January 2018 to December 2019 were retrospectively retrieved from the picture archiving and communication systems (PACS) archives and studied. Ethical clearance was obtained before the commencement of the study from the hospital Health Research and Ethics Committee. Patient consent was not sought because the data were retrieved retrospectively. However, permission was also obtained from the head of department and the hospital management.

All the patients who were referred for cranial MRI on account of suspected intracranial disease were recruited into the study, while patients referred with a suspicion of sinus pathology or head injury were excluded.

Instruments for the study were a 1.5-Tesla Toshiba Excelart Vantage MRI scanner (manufactured in January 2014) and the patient's MRI findings worksheet.

Technique of imaging

All the brain scans were done using a 1.5-Tesla Toshiba Excelart Vantage MRI equipment. Scanning sequences employed included T1-weighted, T2-weighted, diffusion-weighted imaging (DWI), short-T1 inversion recovery (STIR), T2-fluid-attenuated inversion recovery (FLAIR). and time of flight (TOF) sequences. Magnetic resonance (MR) protocols were modified appropriately for individual scans based on specific indications and clinical questions to be answered. Gadolinium-DTPA (Magnevist) was routinely used for contrast enhancement to provide useful additional information. Parents or guardians were permitted to stay with relatives during the scanning to ensure cooperation and to allay their fears. Prior to the scan, the patients are counseled on the use of MRI contrast medium and specific inquiry of the possibility of MRI noncompatible metallic prosthesis or implants in situ is also made.

Positioning

The patients were scanned in the supine position as the patient lies on the couch with head in first and a mattress is placed beneath the patient's knees for comfort. The patient head is centered in the head coil with chin pointing upward; the quadrature head coil is used for optimum signal strength. The patient is given earplugs (for hearing protection), and also immobilization pads and immobilization straps are placed around the head to reduce noise and gross patient movement. The laser light is used to center the patient with the longitudinal alignment line in the midline and the horizontal alignment line across the nasion.

Localizers are obtained in the saggital, axial, and coronal planes for planning. All the brain scans were done using a 1.5-Tesla Toshiba Excelart Vantage MRI equipment. Scanning sequences employed included T1-weighted, T2-weighted, DWI, STIR, T2-FLAIR, and TOF sequences. The sequences are then spin. DWI is also added, especially in brain ischemia and oncology. An accurate weighting is maintained to maximize the desired contrast based on the value of TR and TE. For T1-weighted images, short TR and short TE are employed, while long TR and long TE for T2.

MR protocols were modified appropriately for individual scans based on specific indication and clinical question to be answered. Gadolinium DTPA (diethylenetriamine penta-acetic acid) (Magnevist) Gadolinium-DTPA (Magnevist) was routinely used for contrast enhancement to provide useful additional information.

Claustrophobia is a common challenge that is encountered and such patients were counseled appropriately. Furthermore, to allay the fears of patients and ensure maximum cooperation from them, parents or guardians were permitted to stay with relatives during the scanning.

Only the reports of the brain MRI examinations that were carried out by radiologists were considered for review. The reports and images retrieved from PACS were reviewed jointly by two of the authors who are radiologists. Conflicting opinions were resolved by the third radiologist. Ambiguous reports and those with poor image quality were excluded by consensus agreement of the three authors (radiologists).

The abnormalities detected were complete hyperintensity on T2 and hypointensity on T1 of the sinuses: mucosal thickening, collections with fluid level, and retention cyst/polyp.

A collection with air–fluid level is demonstrable as hyperintense and hypointense on T2- and T1- weighted images respectively.

Mucosal thickening is recognized as a focal or generalized high signal on T2WI and a low signal on T1WI of the mucosal layer lining the bony wall of the sinus.

Retention cyst/polyp is seen commonly as a mass with well-defined smooth margins with areas of hyperintensity on T2WI. Retention cysts and polyps were grouped together as it is often difficult to radiologically differentiate the two pathologies.

The findings were documented in the study worksheet. The data obtained were analyzed using the Statistical Package for the Social Sciences for Windows version 22.0 (SPSS Inc., Chicago, IL, USA).


  Results Top


Four hundred and seventy-nine patients who were referred for brain MRI scans between January 2018 and December 2019 were recruited for the study. The ages ranged from <1 year to 101 years with a mean age of 44.97 ± 23.12 years. There were 232 (48.4%) males and 247 (51.6%) females, giving a male-to-female (M:F) ratio of 1:1.1 [Table 1].
Table 1: Sociodemographic characteristics of the study population

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The prevalence of sinus abnormalities was found to be 26.7%, as seen in one or more sinuses of the patients [Figure 1]. More than half of the abnormal sinuses, 66 (51.6%), were seen in males, while less than half 62 (48.4%) were in females giving an M:F ratio of 1.1:1, which was not statistically significant (P = 0.408), as shown in [Table 2].
Figure 1: Pie chart depicting the distribution of patients with sinus abnormality

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Table 2: Sinus abnormality among males and females

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More than two-third of the patients, 92 (71.8%), had a single sinus affected, while less than a third, 36 (28.2%), had multiple sinuses affected. Seventy-six (82.6%) of the patients with single sinus involvement has the same abnormality affecting the sinus, whereas the same proportion (50%) of single or multiple abnormalities were seen in those who had multiple sinus involvement [Table 3].
Table 3: Frequency of number of sinuses affected and the number of abnormality detected

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[Table 4] displays the spectrum of sinus abnormalities. Fluid collection with air–fluid level [Figure 2]a and [Figure 2]b was the most common, 94 (36.1%), sinus abnormality, followed by mucosal thickening, 92 (35.4%) [Figure 2], [Figure 3], [Figure 4], [Figure 5]. Others are polyp/retention cyst [Figure 3]a, [Figure 3]b, [Figure 3]c, [Figure 3]d, complete hyperintensity and hypointensity on T2 and T1, respectively, of the sinus, mucocele, and hyperpneumatization.
Table 4: Spectrum of the abnormalities in the sinuses

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Figure 2: (a and b) Axial T1 and T2W images showing hypointense and hyperintense collection with an air–fluid level within the left maxillary antrum with marked mucoperiosteal thickening

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Figure 3: (a-d) Axial and coronal T1 and T2W images showing a large polyp within the left maxillary antrum, with bilateral mucoperiosteal thickening

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Figure 4: (a and b) Axial T1 and T2W images showing hypointense and hyperintense collection with air–fluid levels within both maxillary antra with marked mucoperiosteal thickening

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Figure 5: (a-d) Axial and coronal T1W and T2W images showing pansinusitis with mucoperiosteal thickening of the maxillary, ethmoidal, and frontal sinuses

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  Discussion Top


PNS abnormality detected incidentally on imaging is a common finding that has been reported. MRI, a more recent imaging modality, is more sensitive in detecting sinus mucosal abnormalities.[1] The prevalence of sinus abnormality detected incidentally on brain MRI in this Nigerian review was 26.7%. Closely related to this study was the prevalence of 28.3% among Jordanians in the work of Alharazneh et al.[15] Conversely, higher prevalence values have been reported in retrospective reviews in Australia (32.2%),[13] Eastern Nepal (58.1%),[7] and 61%[11] in a prospective study in Germany. The difference in prevalence values compared to this study may be alluded to regional differences. Additional MRI studies in the sub-Saharan region should be done to determine the prevalence among other African communities and to verify the existence of regional differences.

There was no significant relationship between the PNS abnormalities, age, and sex in this study. This is consistent with studies that also correlated incidental sinus abnormalities with age, sex, allergy, smoking habits, previous events of sinusitis, or frequent events of colds.[1],[2],[11] The prevalence of abnormal sinus findings on imaging has been attributed to factors such as climate, frequency of upper respiratory tract infections associated with season, type of study design, age of the study population, criteria for the classification of symptomatic sinus disease, and the definition of the abnormal sinus.[13] A statistically significant difference in the prevalence of abnormal sinus imaging findings has been reported in a prospective study in Denmark that compared symptomatic and nonsymptomatic patients for sinus disease in winter and summer and documented a higher prevalence occurring during the cooler months of winter.[2] This was also corroborated in another study in Australia.[14] Similar prospective studies that will correlate symptoms of sinus disease with imaging findings need to be carried out during the raining (wet) and Harmattan (dry) seasons of tropical Africa.

The maxillary sinus (right, left, and both) was the most frequently involved sinus with an abnormality in this study [Table 5] and this was corroborated by other studies.[1],[7],[8],[9],[15],[16],[17] This was followed by the sphenoid, as was similarly reported by Alharazneh in Jordan and a Nigerian study in Port Harcourt that utilized MRI and plain radiography respectively.[15],[18] The anatomical position of the maxillary sinus predisposes it to poor drainage of fluid and secretions leading to stagnation and subsequent infections. The maxillary sinus is the most commonly affected in inflammatory disease of the sinuses (acute and chronic sinusitis).[19]
Table 5: Frequency and laterality of involvement of the sinuses

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The high frequency of involvement of the sphenoid sinus in pathological process in this study is in divergence to the generally accepted fact that it is the least involved of the sinuses in inflammatory disease. Its low occurrence has also been refuted by the high prevalence of sphenoid sinusitis on CT.[19] The high incidence of sphenoid sinusitis in this study further buttresses the superiority of MRI in sinus imaging. Conversely, the ethmoid sinus was found to be of the highest frequency in a Nigerian study by Oyinloye et al. in Ilorin[20] using CT and also the studies of Wani et al. and Patel et al.[12],[21] The ethmoidal sinuses being the only PNS to undergo cyclical mucosal volume changes was the reason proffered for their finding.[20]

Collection of fluid with distinct air–fluid level was the most common (36.1%) sinus abnormality in this study, and the maxillary sinus was the most affected (32.9%), while complete hyperintensity on T2 and hypointensity on T1 of the sinus was seen in four patients (4.5%). The study in Ilorin, Nigeria, reported 35% of patients with sinus opacification on brain CT scans.[20] Conversely, fluid was a rare finding in the study by Hansen et al[8] in Norway. The appearance of the high intensity of fluid on T2W images using MRI is characteristic and clearly seen.

Mucosal thickening, the second most common sinus abnormality seen in this study, accounted for 34.5% of the cases seen. This was similarly reported by other researchers.[7],[11],[16],[17],[21] The most commonly affected sinus in mucosal thickening in our study was the maxillary sinus, followed by ethmoid, sphenoid, and frontal in decreasing order of frequency. This has been corroborated by other studies.[7],[11],[16]

Retention cysts/polyps which accounted for 25.4% of sinus abnormality recorded in this study are common complications of sinusitis. Other complications of sinusitis include mucoceles, osteomyelitis, and infections (intracranial and intraorbital).[19] Polyps and retention cysts are common, asymptomatic, and incidental findings on imaging that cannot be distinguished from each other on MRI or any other imaging modality; hence, they are generally classified as one pathologic entity.[7],[19] Retention cysts can be mucous or serous retention cyst, the former is more common and is a true cyst as it has an epithelial lining and is formed by the accumulation of secretions from an obstructed mucous gland.[7] The serous cyst on the hand is not a true cyst as it has no epithelial lining and it is formed by the accumulation of fluid in the submucosal layer.[7] On imaging, retention cyst is commonly seen as a mass with well-defined smooth margins. Retention cyst was found in the maxillary sinus (30.6% of cases) in this study, and this was similar to a study carried out by Gupta et al.[7] in eastern Nepal.

Sinus findings were mentioned in 368 (76.8%) of the reports of the radiologist in this study. This is significant since the indications for the referrals for the MRI scans were not for sinus or ear, nose, and throat (ENT) pathology. In another study, sinus abnormalities were mentioned in 8.1% of the radiologist reports.[14] In view of the high prevalence of incidental sinus findings on imaging, it has been advocated that radiologists should apply caution in making the radiological diagnosis of “sinusitis” when reporting brain imaging studies for non-ENT indications[11] so as not to raise undue pressure of treatment dilemma. It is therefore necessary that a detailed clinical evaluation which involves obtaining history in the imaging department should be done to correlate MRI or imaging sinus findings.[22] However, its detection as an incidental finding on imaging may be a pointer to an early and subclinical onset of sinus pathology.


  Conclusion Top


This study has established a prevalence rate of 26.7% as the incidental abnormal sinus finding on brain MRI, buttressing the fact that morphological changes in the PNSs are frequently encountered incidentally on imaging. There is hence a need to obtain relevant history of sinus pathology from patients undergoing brain imaging to aid prompt diagnosis of subclinical sinus disease and achieve optimal therapeutic outcomes.

The limitation of our study being a retrospective study was that there was no correlation of the symptoms of sinus disease with imaging findings of the abnormal sinuses in the study population who underwent MRI of the brain for non-ENT indication.

Criteria for diagnosing pathological MRI findings in the PNSs are desirable and might improve the basis for a decision on the correct medical or surgical treatment of sinus disease. We intend to extend our study in future to a larger population to evaluate these findings further and also to correlate our findings with the patients' symptoms in that study.

Acknowledgment

The authors are indebted to Dr Obiebe Irikefe and Osas for the statistical/data analysis and also to the following radiology resident doctors for their assistance: Otakhoigbogie Iyobosa; Amromano S; Demaki A; Okpeva J; Ehroma P, and Oheri B.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Nazri M, Bux SI, Tengku-Kamalden TF, Ng KH, Sun Z. Incidental detection of sinus mucosal abnormalities on CT and MRI imaging of the head. Quant Imaging Med Surg 2013;3:82-8.  Back to cited text no. 1
    
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Cooke LD, Glasgow DM. MRI of the paranasal sinuses: Incidental abnormalities and their relationship to symptoms. J Laryngol Otol 1991;105:278-81.  Back to cited text no. 4
    
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Scadding G, Hellings P, Alobid I, Bachert C, Fokkens W, van Wijk RG, et al. Diagnostic tools in rhinology EAACI position paper. Clin Transl Allergy 2011;1:2.  Back to cited text no. 6
    
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Hansen AG, Helvik AS, Nordgård S, Bugten V, Stovner LJ, Håberg AK, et al. Incidental findings in MRI of the paranasal sinuses in adults: A population-based study (HUNT MRI). BMC Ear Nose Throat Disord 2014;14:13-9.  Back to cited text no. 8
    
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Maharjan S. Assessment of paranasal sinuses in magnetic resonance imaging of brain. Bangabandhu Sheikh Mujib Med Univ J 2016;9:104-6.  Back to cited text no. 9
    
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Wani MK, Ruckenstein MJ, Parikh S. Magnetic resonance imaging of the paranasal sinuses: Incidental abnormalities and their relationship to patient symptoms. J Otolaryngol 2001;30:257-62.  Back to cited text no. 12
    
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Lim WK, Ram B, Fasulakis S, Kane KJ. Incidental magnetic resonance image sinus abnormalities in asymptomatic Australian children. J Laryngol Otol 2003;117:969-72.  Back to cited text no. 13
    
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Alharazneh A, Hamdan O, Alrawashdeh HM and Baqain Y. Incidental Nasal and Paranasal Findings on MRI and CT Scans-A Prospective Study. Prensa Med Argent. 2020:2: 191.  Back to cited text no. 15
    
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McNeill E, O'Hara J, Carrie S. The significance of MRI findings for non-rhinological disease. Clin Otolaryngol 2006;31:292-6.  Back to cited text no. 17
    
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20.
Oyinloye OI, Akande JA, Alabi BS, Afolabi OA. incidental paranasal sinus abnormalites on cranial computed tomography in a Nigerian population. Ann Afr Med 2013;12:62-4.  Back to cited text no. 20
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21.
Patel K, Chavda SV, Violaris N, Pahor AL. Incidental paranasal sinus inflammatory changes in a British population. J Laryngol Otol 1996;110:649-51.  Back to cited text no. 21
    
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Gutmann A. Ethics. The bioethics commission on incidental findings. Science 2013;342:1321-3.  Back to cited text no. 22
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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