Incidental findings in MRI of the paranasal sinuses in adults: a population-based study (HUNT MRI)

Background Diagnostic imaging of the head is used with increasing frequency, and often includes the paranasal sinuses, where incidental opacifications are found. To determine the clinical relevance of such findings can be challenging, and for the patient such incidental findings can give rise to concern if they are over-reported. Studies of incidental findings in the paranasal sinuses have been conducted mostly in patients referred for diagnostic imaging, hence the prevalence in the general population is not known. The purpose of this study was to determine the prevalence and size of incidental opacification in the paranasal sinuses in a non-selected adult population using magnetic resonance imaging (MRI) without medical indication, and to relate the results to sex and season. Methods Randomly and independent of medical history, 982 participants (518 women) with a mean age of 58.5 years (range, 50–66) underwent MRI of the head as part of a large public health survey in Norway. The MRIs included 3D T1 weighted volume data and 2D axial T2 weighted image (WI). Opacifications, indicating mucosal thickenings, polyps, retention cysts, or fluid, were recorded if measuring more than 1 mm. Results Opacifications were found in 66% of the participants. Mucosal thickenings were found in 49%, commonly in the maxillary sinuses (29%) where 25% had opacifications that were less than 4 mm in size. Other opacifications occurred in the anterior ethmoid (23%), posterior ethmoid (21%), frontal sinus (9%), and sphenoid (8%). Polyps and retention cysts were also found mainly in the maxillary sinuses in 32%. Fluid was observed in 6% of the MRIs. Mucosal thickening was observed more frequently in men than in women (P <0.05). No seasonal variation was found. Conclusions In this large non-selected sample, incidental opacification in the paranasal sinuses was seen in two out of three participants, and mucosal thickening was seen in one out of two. Fluid was rare. Knowledge of incidental opacification is important because it can affect clinical practice

Incidental Intracranial Findings and Their Clinical Impact; The HUNT MRI Study in a General Population of 1006 Participants between 50-66 Years

Objectives Evaluate types and prevalence of all, incidental, and clinically relevant incidental intracranial findings, i.e. those referred to primary physician or clinical specialist, in a cohort between 50 and 66 years from the Nord-Trøndelag Health (HUNT) study. Types of follow-up, outcome of repeated neuroimaging and neurosurgical treatment were assessed. Material and Methods 1006 participants (530 women) underwent MRI of the head at 1.5T consisting of T1 weighted sagittal IR-FSPGR volume, axial T2 weighted, gradient echo T2* weighted and FLAIR sequences plus time of flight cerebral angiography covering the circle of Willis. The nature of a finding and if it was incidental were determined from previous radiological examinations, patient records, phone interview, and/or additional neuroimaging. Handling and outcome of the clinically relevant incidental findings were prospectively recorded. True and false positives were estimated from the repeated neuroimaging. Results Prevalence of any intracranial finding was 32.7%. Incidental intracranial findings were present in 27.1% and clinically relevant findings in 15.1% of the participants in the HUNT MRI cohort. 185 individuals (18.4%) were contacted by phone about their findings. 40 participants (6.2%) underwent ≥ 1 additional neuroimaging session to establish etiology. Most false positives were linked to an initial diagnosis of suspected glioma, and overall positive predictive value of initial MRI was 0.90 across different diagnoses. 90.8% of the clinically relevant incidental findings were developmental and acquired cerebrovascular pathologies, the remaining 9.2% were intracranial tumors, of which extra-axial tumors predominated. In total, 3.9% of the participants were referred to a clinical specialist, and 11.7% to their primary physician. 1.4% underwent neurosurgery/radiotherapy, and 1 (0.1%) experienced a procedure related postoperative deficit. Conclusions In a general population between 50 and 66 years most intracranial findings on MRI were incidental, and >15% of the cohort was referred to clinical-follow up. Hence good routines for handling of findings need to be in place to ensure timely and appropriate handling

Flow diagram and overview of inclusion and exclusion of participants in the HUNT MRI study, the types and prevalence of classes of intracranial findings, follow up and outcome in the included participants.

<p>Flow diagram and overview of inclusion and exclusion of participants in the HUNT MRI study, the types and prevalence of classes of intracranial findings, follow up and outcome in the included participants.</p

Examples of the different scan sequences and incidental intracranial findings in the HUNT MRI cohort, i.e. meningioma (T1W 3D), glioma (FLAIR), arteriovenous malformation (T2* weighted), arachnoidal cyst (T2W weighted), aneurysms (Time of Flight angio) and silent infarctions (T1W 3D scan).

<p>Examples of the different scan sequences and incidental intracranial findings in the HUNT MRI cohort, i.e. meningioma (T1W 3D), glioma (FLAIR), arteriovenous malformation (T2* weighted), arachnoidal cyst (T2W weighted), aneurysms (Time of Flight angio) and silent infarctions (T1W 3D scan).</p

False and true positive intracranial findings and positive predictive value of initial MRI based on follow-up neuroimaging in participants in the HUNT MRI cohort with a suspected neurosurgical condition.

<p>False and true positive intracranial findings and positive predictive value of initial MRI based on follow-up neuroimaging in participants in the HUNT MRI cohort with a suspected neurosurgical condition.</p

Number and prevalence intracranial findings stratified into total number of findings, participants with findings, distribution of findings between men and women, total incidental findings, and number of individuals with incidental findings with clinical impact in the HUNT-MRI cohort of 1006 participants (476 men and 530 women).

<p>Number and prevalence intracranial findings stratified into total number of findings, participants with findings, distribution of findings between men and women, total incidental findings, and number of individuals with incidental findings with clinical impact in the HUNT-MRI cohort of 1006 participants (476 men and 530 women).</p

Typical examples of Fazekas grade 1, 2 and 3 white matter hyperintensities (WMH).

<p>The examples are from the FLAIR scans of three HUNT MRI participants.</p

Scan parameters for the different sequences in HUNT MRI.

<p>Scan parameters for the different sequences in HUNT MRI.</p