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.

Perivascular spaces and headache: A population-based imaging study (HUNT-MRI).

BACKGROUND: In four previous clinic-based MRI studies headache sufferers (in particular migraineurs) had more perivascular spaces (PVS) than individuals who were headache-free. METHODS: The present study was part of a large longitudinal, epidemiological study (Nord-Trøndelag Health Survey (HUNT)). The 1006 participants, age 50-65 years at inclusion, had participated in all previous HUNT surveys (1-3), and been randomly selected to a population-based imaging study of the head (HUNT-MRI, 2007-2009). The number of visible PVS in the basal ganglia (BG) and hemispheric white matter (HWM) was compared in headache sufferers (migraine with and without aura, non-migrainous headache) and people who were headache-free. RESULTS: The results showed in general small differences between headache sufferers and headache-free participants. In the cross-sectional analysis migraineurs without aura had fewer PVS than headache-free individuals in BG (OR = 0.84, 95% CI = 0.76--0.94, p value = 0.003) and in BG and HWM together (OR = 0.97, 95% CI = 0.95-1.00, p value = 0.046). No difference between long-term headache sufferers and long-term headache-free individuals with regard to number of PVS was found. DISCUSSION: In contrast to previous studies, the present large, blinded, population-based study showed no increase in number of dilated PVS among headache sufferers. Fewer PVS among those with migraine without aura may be a spurious finding.

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.

Unruptured intracranial aneurysms in the Norwegian Nord-Trøndelag Health Study (HUNT): risk of rupture calculated from data in a population-based cohort study.

BACKGROUND: Rupture risk of unruptured intracranial aneurysms (UIAs) has been investigated in studies observing the natural history of this condition. Such studies have been prone to selection bias that may influence the results. OBJECTIVE: To calculate the overall rupture risk from data on the prevalence of UIA, which constitutes the population at risk, and the incidence of aneurysmal subarachnoid hemorrhage (aSAH) in the same population. METHODS: Data were collected from the Norwegian Nord-Trøndelag Health Study (HUNT), a large population-based cohort study. The prevalence of UIAs was estimated by performing magnetic resonance angiography in 1006 randomly selected volunteers 50 to 65 years of age from this population cohort. The incidence of aSAH was investigated by searching national and hospital registers with thorough case ascertainment to avoid inclusion of nonaneurysmal subarachnoid hemorrhage. RESULTS: The prevalence of UIAs was 1.9% and incidence of aSAH was 16.4 per 100,000 person-years. Based on these figures, the overall rupture risk in the 50- to 65-year age group in the HUNT population is 0.87% per year. CONCLUSION: This is the first study to estimate rupture risk of intracranial aneurysms from epidemiologic data in a large population-based cohort. This study design is less prone to selection bias and may provide an important supplement to the existing literature of studies of natural history of UIAs.

Cerebrospinal fluid from patients with dementia contains increased amounts of an unknown factor.

Increased levels of an unidentified peak have been found in cerebrospinal fluid (CSF) from patients with Alzheimer's disease or vascular dementia compared to the level in healthy controls using proton magnetic resonance spectroscopy. No increase was found in patients with amyotrophic lateral sclerosis. Reexamination of spectra from a study published previously (Gårseth et al. [2000] J. Neurosci. Res. 60:779-782), however, shows that this peak was also elevated significantly in CSF from patients with Huntington's disease compared to that in controls. The level in patients with Parkinson's disease, where dementia develops in up to 40% of patients, was not elevated significantly compared to that in controls. To the best of our knowledge, this peak has not yet been identified and we therefore find it appropriate to temporarily designate the name "dementia associated factor" (DAF), although there is as yet no certainty that this substance is specific for these conditions. Apart from a significantly increased level of glutamine in CSF from patients with vascular dementia compared to that in controls, no other significant difference was found for any other metabolite measured in the patient groups using proton magnetic resonance spectroscopy.

Metabolic changes in the cerebrospinal fluid of patients with lumbar disc herniation or spinal stenosis.

Metabolite levels in cerebrospinal fluid from patients with lower back pain and/or sciatica caused by disc herniation or spinal stenosis were compared with levels in pain-free controls using proton magnetic resonance spectroscopy. Significant differences for several metabolites were found in patients with pain compared with controls. Most changes were found in the group with disc herniation, including reductions in glucose, alanine, and lactate, suggesting increased aerobic metabolism in this group. There was a significant reduction in the level of glucose in the group with spinal stenosis irrespective of whether the patients were compared with the whole control group (age-weighted) or with age-matched controls. Additionally, inositol and creatinine were reduced in patients with disc herniation. Inositol was also significantly reduced in the spinal stenosis group when age matched to controls. Insofar as the levels of pain recorded by the patients with lumbar pathology were similar in the two groups, it seems more likely that the reductions in metabolite levels recorded in the group with disc herniations are related to disc pathology rather than the perception of pain. However, the possibility that pain perception contributes to the metabolic changes cannot be excluded.