Does Gadolinium Deposition Lead to Metabolite Alteration in the Dentate Nucleus? An MRS Study in Patients with MS.

BACKGROUND AND PURPOSE: Repeat contrast-enhanced MR imaging exposes patients with relapsing-remitting MS to frequent administration of gadolinium-based contrast agents. We aimed to investigate the potential metabolite and neurochemical alterations of visible gadolinium deposition on unenhanced T1WI in the dentate nucleus using MRS. MATERIALS AND METHODS: This prospective study was conducted in a referral university hospital from January 2020 to July 2021. The inclusion criteria for case and control groups were as follows: 1) case: patients with relapsing-remitting MS, visible gadolinium deposition in the dentate nucleus (ribbon sign), >5 contrast-enhanced MR images obtained; 2) control 1: patients with relapsing-remitting MS without visible gadolinium deposition in the dentate nucleus, >5 contrast-enhanced MR images obtained; 3) control 2: patients with relapsing-remitting MS without visible gadolinium deposition in the dentate nucleus, <5 contrast-enhanced-MR images obtained; and 4) control 3: adult healthy individuals, with no contrast-enhanced MR imaging. Dentate nucleus and pontine single-voxel 12 × 12 × 12 MRS were analyzed using short TEs. RESULTS: Forty participants (10 per group; 27 [67.5%] female; mean age, 35.6 [SD, 9.6] years) were enrolled. We did not detect any significant alteration in the levels of NAA and choline between the studied groups. The mean concentrations of mIns were 2.7 (SD, 0.73) (case), 1.5 (SD, 0.8) (control 1), 2.4 (SD, 1.2) (control 2), and 1.7 (SD, 1.2) (control 3) (P = .04). The mean concentration of Cr and mIns (P = .04) and the relative metabolic concentration (dentate nucleus/pons) of lipid 1.3/Cr (P = .04) were significantly higher in the case-group than in healthy individuals (controls 1-3). Further analyses compared the case group with cumulative control 1 and 2 groups and showed a significant increase in lactate (P = .02), lactate/Cr (P = .04), and Cr (dentate nucleus/pons) (P = .03) in the case group. CONCLUSIONS: Although elevated concentrations of Cr, lactate, mIns, and lipid in the dentate nucleus of the case group indicate a metabolic disturbance, NAA and choline levels were normal, implying no definite neuronal damage.

Increasing exophthalmia after carotid-cavernous fistula closure with a detachable balloon: problems of incomplete treatment. A case report.

A 30-year-old woman with pulsating exophthalmia due to posttraumatic carotid-cavernous fistula underwent embolization with a detachable balloon. Because of balloon dislodgement, the drainage was derived to the superior ophthalmic vein and clinical worsening occurred. Complete ophthalmoplegia developed and visual acuity decreased. After a second embolization we inserted two balloons but the same findings were exaggerated. Finally coiling of the internal carotid artery was done and orbital decompression achieved. Ophthalmoplegia, proptosis, chemosis and nerve paralysis intraocular pressure improved.

Evaluation of angiographic findings in spontaneous aneurysmal subarachnoid hemorrhage patients.

This paper describes the angiographic findings of spontaneous aneurysmal subarachnoid hemorrhage (SAH) patients, including frequency, anatomic location and multiplicity of cerebral aneurysms. We retrospectively reviewed the records of 796 SAH patients at our university affiliated hospital. After confirming SAH by lumbar puncture or CT scan, all patients underwent digital subtraction angiography to find the definite anatomic location. The male to Female ratio in SAH patients was 9:10. The mean (SD) age of all patients with SAH was 47.9±14.7 years. The mean (SD) age of men with SAH was 46.6 ±15.6 years and women with SAH was 49.3±13.5 years (P=0.015). 357 (44.8%) patients had aneurysms. The mean (SD) age of aneurysmal patients was 49.8±14.3 years. The mean (SD) age of men with aneurysm was 47.8 ±15.9 years and women with aneurysm was 51.3±12.9 years (P= 0.03). The male to female ratio in aneurysms was 0.72:1. The most common aneurysm location was in the anterior communicating artery (N=166, 39%). The second most common anatomic location was the middle cerebral artery bifurcation (66 left, 60 right). The total number of patients with single aneurysms was 303 (84.9%) while 54 (15.1%) patients had multiple aneurysms. Among these patients, 49 had two aneurysms, three had three aneurysms and two had four aneurysms. In all, 418 aneurysms were detected. Of 357 patients with aneurysms 150 (42%) had vasospasm during angiography. In conclusion, the most common aneurysm location was the anterior communicating artery and the rate of multiplicity was also higher in our patients.

MR relaxivity measurement of iron oxide nano-particles for MR lymphography applications.

The aim of this study was to assess the T1, T2 and T2* relaxivity of Ultrasmall Super Paramagnetic Iron Oxide (USPIO) nano-particles in vitro and in vivo in rat models with magnetic resonance imaging at 1.5T. First, relaxation properties of USPIO nano-particles at different doses were measured using related SE and GRE MR imaging protocols. The relation between dose and relaxation were observed which is linear; Higher dose of the nano-particles means higher relaxivity. Based on this relation, an optimum protocol can be proposed for obtaining the best image contrast at each situation. Then detection ability of MRI protocols was studied for USPIO nano-particles with injection of the particles in the rat. The optimum MR protocols were used to observe the signal change of lymph nodes in rat.

Spatial frequency modulates visual cortical response to temporal frequency variation of visual stimuli: an fMRI study.

The brain response to temporal frequency (TF) variation has already been reported, but with no study for different TF with respect to various spatial frequencies (SF). Functional magnetic resonance imaging (fMRI) was performed with a 1.5 Tesla General Electric system in 14 volunteers during square-wave reversal checkerboard visual stimulation with different temporal frequencies of 4, 6, 8 and 10 Hz in two states of low SF of 0.4 and high SF of 8 cpd (cycles/degree). The activation map was created using the data obtained from the block-designed fMRI study. Voxels whose Z value was above a threshold of 3.0, at a significance level P = 0.05, were considered activated. The results demonstrated that the percentage BOLD signal change in response to different TFs was the maximum value at 6 Hz for a high SF of 8 cpd, whereas it was the maximum at TF of 8 Hz for a low SF of 0.4 cpd. The results of this study agree with the results of animal invasive neurophysiological studies showing spatial and temporal frequency selectivity of neurons in visual cortical areas. These results can be useful for vision therapy (such as the treatment of amblyopia) and selecting a visual task in fMRI studies.

Spatial frequency modulates the human visual cortical response to temporal frequency variation: an fMRI study.

The brain response to temporal frequencies (TF) has been already reported, but with no study for different TFs with respect to various spatial frequencies (SF). Functional Magnetic Resonance Imaging (fMRI) experiments were performed by 1.5 Tesla General Electric-system in 14 volunteers (9 males and 5 females, range 19-26 years) during square-wave reversal checkerboard visual stimulation with different temporal frequencies of 4, 6, 8 and 10 Hz in two states of low SF of 0.5 and high SF of 8 cpd (cycles/degree). The activation map was created using the data obtained from the block designed fMRI study. Pixels whose correlation coefficient value was above a threshold of 0.33, in significant level P<0.01 were considered activated. The average percentage BOLD (blood oxygenation level dependent) signal change for all activated pixels within the occipital lobe, multiplied by the total number of activated pixels within the occipital lobe, was used as the criterion for the strength of the fMRI signal at each state of TF&SF. The results demonstrated that the strength of the fMRI signal in response to different TFs was maximum in 6Hz for high SF of 8 cpd, while it was maximum at TF of 8Hz for low SF of 0.5 cpd. The results of this study agree with the results of animal invasive neurophysiological studies showing spatial and temporal frequency selectivity of neurons in visual cortical areas. These results can be useful for vision therapy (such as the treatment of Amblyopia) and selecting visual task in fMRI studies.