MRI of endolymphatic hydrops in patients with Meniere's disease: a case-controlled study with a simplified classification based on saccular morphology.

OBJECTIVES: Endolymphatic hydrops (EH) can be studied in patients by MRI. With the semi-quantitative grading system, previous imaging studies showed discrepancies in the occurrence and grading of EH in patients with Meniere's disease (MD). Here, we compared the inversion of the saccule to utricle area ratio (SURI) with the semi-quantitative method of grading conventionally used to diagnose MD. METHODS: Imaging was carried out on a 3-T MRI scanner. We performed 3D-FLAIR sequences 4 h after a single intravenous dose of contrast agent. Two radiologists independently studied the morphology of the inner ear structures in the healthy subjects and MD patients. Each subject was then graded on the basis of the EH semi-quantitative analysis and on saccular morphology using axial and sagittal reference slices in the vestibule plane. RESULTS: Thirty healthy subjects and 30 MD patients had MRI scans. Using the semi-quantitative method, we found no significant difference in the number of subjects with EH between the two groups. SURI was found in 15 out of 30 MD patients and in none of the 30 healthy subjects. In three MD patients the saccule was not visible. CONCLUSION: SURI is currently the most specific criterion for imaging diagnosis of MD. KEY POINTS: • Half of MD patients presented with inversion of the saccule to utricle ratio. • Saccular analysis is crucial when assessing patients with Meniere's disease. • In some patients, the saccule is not visible, suggestive of intra-labyrinthine fistulae.

Altered signal intensity of active enhancing inflammatory lesions using post-contrast double inversion recovery MR sequence.

OBJECTIVES: We aimed at establishing the impact upon gadolinium administration on the conspicuity of active enhancing multiple sclerosis (MS) lesions using double inversion recovery (DIR) at 3T. METHODS: 15 consecutive patients with MS (n=8) or a clinically isolated syndrome (n=7) underwent pre and post-contrast DIR in addition to T2-weighted, FLAIR, pre and post-contrast T1-weighted sequences. First, two neuroradiologists located and marked all the enhancing MS lesions visible in consensus. Second, two other neuroradiologists, blinded to other sequences than DIR, independently assessed the SI changes from pre to post-contrast DIR images for each enhancing lesion, according to a 4-point-scale: increased SI (grade 1), absence of change (grade 2), lesion being partially (grade 3) or completely masked on post-contrast DIR images (grade 4). RESULTS: 246 MS lesions were detected including 26 enhancing on post-contrast T1-weighted images in 9 patients. The two blinded readers concluded to a decreased signal-intensity on post-contrast DIR images for all the 26 enhancing MS lesions (14 of grade 3 and 12 of grade 4). Inter-observer agreement was excellent, Kappa=0.85 (0.75 - 0.94). Using DIR post-contrast leads to altered signal-intensity of enhancing active MS lesions, ranging from partial to complete signal-loss. CONCLUSION: Our study strongly suggests the use of DIR before gadolinium administration. KEY POINTS: • DIR has gained widespread use in MS. • MRI protocols for MS patients usually contain several post-contrast sequences. • Signal-intensity of enhancing MS lesions is altered using DIR post-contrast. • Our study strongly suggests the use of DIR before gadolinium administration.

Reduced CMRO2 and cerebrovascular reserve in patients with severe intracranial arterial stenosis: a combined multiparametric qBOLD oxygenation and BOLD fMRI study.

Multiparametric quantitative blood oxygenation level dependent (mqBOLD) magnetic resonance Imaging (MRI) approach allows mapping tissular oxygen saturation (StO2 ) and cerebral metabolic rate of oxygen (CMRO2 ). To identify hemodynamic alteration related to severe intracranial arterial stenosis (SIAS), functional MRI of cerebrovascular reserve (CVR BOLD fMRI) to hypercapnia has been proposed. Diffusion imaging suggests chronic low grade ischemia in patients with impaired CVR. The aim of the present study was to evaluate how oxygen parameters (StO2 and CMRO2 ), assessed with mqBOLD approach, correlate with CVR in patients (n = 12) with SIAS and without arterial occlusion. The perfusion (dynamic susceptibility contrast), oxygenation, and CVR were compared. The MRI protocol conducted at 3T lasted approximately 1 h. Regions of interest measures on maps were delineated on segmented gray matter (GM) of middle cerebral artery territories. We have shown that decreased CVR is spatially associated with decreased CMRO2 in GM of patients with SIAS. Further, the degree of ipsilateral CVR reduction was well-correlated with the amplitude of the CMRO2 deficit. The altered CMRO2 suggests the presence of a moderate ischemia explained by both a decrease in perfusion and in CVR. CVR and mqBOLD method may be helpful in the selection of patients with SIAS to advocate for medical therapy or percutaneous transluminal angioplasty-stenting.

Study of proximal femoral bone perfusion with 3D T1 dynamic contrast-enhanced MRI: a feasibility study.

OBJECTIVE: The objective of this study was to compare measurements of semi-quantitative and pharmacokinetic parameters in areas of red (RBM) and yellow bone marrow (YBM) of the hip, using an in-house high-resolution DCE T1 sequence, and to assess intra- and inter-observer reproducibility of these measurements. METHODS: The right hips of 21 adult patients under 50 years of age were studied. Spatial resolution was 1.8 × 1.8 × 1.8 mm(3), and temporal resolution was 13.5 seconds. Two musculoskeletal radiologists independently processed DCE images and measured semi-quantitative and pharmacokinetic parameters in areas of YBM and RBM. Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were calculated. Intra- and inter-observer reproducibility was assessed. RESULTS: Area under the curve (AUC) and initial slope (IS) were significantly greater for RBM than for YBM (p < 0.05). K(trans) and kep were also significantly greater for RBM (p < 0.05). There was no significant difference in time to peak between the regions (p < 0.05). SNR, CNR, and intra- and inter-observer reproducibility were all good. CONCLUSIONS: DCE study of the whole hip is feasible with high spatial resolution using a 3D T1 sequence. Measures were possible even in low vascularized areas of the femoral head. K(trans), kep, AUC, and IS values were significantly different between red and yellow marrow, whereas TTP values were not. KEY POINTS: High-spatial-resolution dynamic contrast-enhanced MRI of hip structures is feasible. Intra- and inter-observer reproducibility is good. Red and yellow bone marrow have different perfusion patterns.

Comparison of 3D double inversion recovery and 2D STIR FLAIR MR sequences for the imaging of optic neuritis: pilot study.

OBJECTIVES: We compared the three-dimensional (3D) double inversion recovery (DIR) magnetic resonance imaging (MRI) sequence with the coronal two-dimensional (2D) short tau inversion recovery (STIR) fluid-attenuated inversion recovery (FLAIR) for the detection of optic nerve signal abnormality in patients with optic neuritis (ON). METHODS: The study group consisted of 31 patients with ON (44 pathological nerves) confirmed by visual-evoked potentials used as the reference. MRI examinations included 2D coronal STIR FLAIR and 3D DIR with 3-mm coronal reformats to match with STIR FLAIR. Image artefacts were graded for each portion of the optic nerves. Each set of MR images (2D STIR FLAIR, DIR reformats and multiplanar 3D DIR) was examined independently and separately for the detection of signal abnormality. RESULTS: Cisternal portion of optic nerves was better delineated with DIR (p < 0.001), while artefacts impaired analysis in four patients with STIR FLAIR. Inter-observer agreement was significantly improved (p < 0.001) on 3D DIR (κ = 0.96) compared with STIR FLAIR images (κ = 0.60). Multiplanar DIR images reached the best performance for the diagnosis of ON (95% sensitive and 94% specific). CONCLUSIONS: Our study showed a high sensitivity and specificity of 3D DIR compared with STIR FLAIR for the detection of ON. These findings suggest that the 3D DIR sequence may be more useful in patients suspected of ON. KEY POINTS: 3D DIR is increasingly used in neuroradiology. Compared with STIR FLAIR, 3D DIR improves detection of optic neuritis. Multiplanar analysis had the best diagnostic performance for optic nerve signal abnormalities. Sensitivity was 95% and specificity 94%. Findings support the use of 3D DIR instead of 2D sequences.

Technical Note: Clinical translation of the Rapid-Steady-State-T1 MRI method for direct cerebral blood volume quantification.

PURPOSE: In preclinical studies, the Rapid-Steady-State-T1 (RSST1) MRI method has advantages over conventional MRI methods for blood volume fraction (BVf) mapping, since after contrast agent administration, the BVf is directly quantifiable from the signal amplitude corresponding to the vascular equilibrium magnetization. This study focuses on its clinical implementation and feasibility. METHODS: Following sequence implementation on clinical Philips Achieva scanners, the RSST1-method is assessed at 1.5 and 3 T in the follow-up examination of neurooncological patients receiving 0.1-0.2 mmol/kg Gd-DOTA to determine the threshold dose needed for cerebral BVf quantification. Confounding effects on BVf quantification such as transendothelial water exchange, transverse relaxation, and contrast agent extravasation are evaluated. RESULTS: For a dose≥0.13 mmol/kg at 1.5 T and ≥0.16 mmol/kg at 3 T, the RSST1-signal time course in macrovessels and brain tissue with Gd-DOTA impermeable vasculature reaches a steady state at maximum amplitude for about 8 s. In macrovessels, a BVf of 100% was obtained validating cerebral microvascular BVf quantification (3.5%-4.5% in gray matter and 1.5%-2.0% in white matter). In tumor tissue, a continuously increasing signal is detected, necessitating signal modeling for tumor BVf calculation. CONCLUSIONS: Using approved doses of Gd-DOTA, the steady state RSST1-signal in brain tissue is reached during the first pass and corresponds to the BVf. The first-pass duration is sufficient to allow accurate BVf quantification. The RSST1-method is appropriate for serial clinical studies since it allows fast and straightforward BVf quantification without arterial input function determination. This quantitative MRI method is particularly useful to assess the efficacy of antiangiogenic agents.

Brain iron levels in attention-deficit/hyperactivity disorder: a pilot MRI study.

OBJECTIVE: Brain iron deficiency has been supposed to be involved in the pathophysiology of ADHD. Available studies assessing iron in ADHD are based on serum ferritin, a peripheral marker of iron status. To what extent serum ferritin correlates with brain iron (BI) is unclear. The main aim of this study was to compare BI, estimated with magnetic resonance imaging (MRI) in the putamen, pallidum, caudate, and thalamus, between children with and without ADHD. The secondary aim was to assess the correlation between serum ferritin and BI levels. METHODS: Thirty-six children (18 with and 18 without ADHD, the latter including nine healthy controls and nine psychiatric controls) completed MRI and blood sampling. Brain iron levels were estimated by imaging T2*. RESULTS: Children with ADHD showed significantly lower estimated BI in right and left thalamus compared to healthy controls. Estimated BI did not differ significantly between children with ADHD and psychiatric controls. Children with ADHD had significantly lower levels of serum ferritin than healthy as well as psychiatric controls. Serum ferritin and T2* values did not correlate significantly in most regions. CONCLUSIONS: Low iron in the thalamus may contribute to ADHD pathophysiology.

Diffusion-weighted MR imaging sequence in the detection of postoperative recurrent cholesteatoma.

PURPOSE: To prospectively evaluate a fast spin-echo (SE) diffusion-weighted sequence for magnetic resonance (MR) imaging of recurrent cholesteatoma in patients who have undergone middle ear surgery. MATERIALS AND METHODS: The study was approved by the institutional review board, and informed consent was obtained from all patients. Twenty-four patients (10 female and 14 male patients; mean age, 44 years) who had undergone resection of cholesteatoma were referred for MR imaging. MR imaging was performed with a 1.5-T unit by using unenhanced diffusion-weighted fast SE imaging at b factors of 0 and 800 sec/mm(2), unenhanced T2-weighted fast SE imaging, unenhanced T1-weighted SE imaging, and delayed contrast material-enhanced T1-weighted imaging. Two radiologists evaluated the diffusion-weighted fast SE images for the presence of a high-signal-intensity cholesteatoma. Results from MR imaging were compared with reports from second- or third-look surgery. Interobserver agreement was assessed with the kappa statistic. RESULTS: A recurrent cholesteatoma was correctly identified in 13 of 14 patients with diffusion-weighted fast SE images obtained with a b factor of 800 sec/mm(2), for a positive predictive value of 93%. In patients without recurrent cholesteatoma, all diffusion-weighted fast SE MR images obtained with a b factor of 800 sec/mm(2) were correctly interpreted as showing no high signal intensity. Thus, the negative predictive value was 100%. Sensitivity and specificity were 100% (13 of 13 patients) and 91% (10 of 11 patients), respectively. Interobserver agreement was excellent (kappa = 0.92). The smallest recurrent cholesteatoma was 5 mm in diameter, and this was correctly detected with the diffusion-weighted fast SE sequence. CONCLUSION: Diffusion-weighted fast SE imaging enables the depiction of recurrent cholesteatoma in patients who have undergone middle ear surgery.