First Measurement of Signal Changes Induced by Ionizing Radiation in Magnetic Resonance Imaging

2013 ◽  
Vol 80 (11) ◽  
Author(s):  
Markus Rausch ◽  
Felix Schyboll ◽  
Heiko Neeb
Keyword(s):  
Magnetic Resonance Imaging ◽  
Linear Accelerator ◽  
Theoretical Basis ◽  
Resonance Imaging ◽  
Simple Theoretical Model ◽  
Signal Change ◽  
Phase Signal ◽  
Signal Changes ◽  
Phase Signal Change ◽  
Pet Scanners

AbstractThere is an increasing tendency towards the use of combined MR/PET scanners and combined MR-Linac (Linear accelerator) systems in both clinical and research settings. The current work therefore investigated the effects of ionising radiation on the acquired MR signal, both experimentally and using a simple theoretical model. We have observed a phase signal change in the radiated area inside a water phantom. However, the theoretical basis of this observation is not fully covered by the employed model and needs further research.

scholarly journals Crossed Cerebellar Diaschisis: Insights into Oxygen Challenge MRI

2012 ◽  
Vol 32 (12) ◽  
pp. 2114-2117 ◽  
Author(s):  
Krishna A Dani ◽  
Celestine Santosh ◽  
David Brennan ◽  
Donald M Hadley ◽  
Keith W Muir
Keyword(s):  
Magnetic Resonance Imaging ◽  
Cerebral Blood Volume ◽  
Oxygen Extraction Fraction ◽  
Resonance Imaging ◽  
Crossed Cerebellar Diaschisis ◽  
Relative Contribution ◽  
Extraction Fraction ◽  
Signal Change ◽  
Cerebellar Diaschisis ◽  
Weighted Magnetic Resonance Imaging

Hyperoxia during T2∗-weighted magnetic resonance imaging (oxygen challenge imaging (OCI)) causes T2∗-weighted signal change that is dependent on cerebral blood volume (CBV) and oxygen extraction fraction (OEF). Crossed cerebellar diaschisis (CCD), where CBV is reduced but OEF is maintained, may be used to understand the relative contributions of OEF and CBV to OCI results. In subjects with large hemispheric strokes, OCI showed reduced signal change in the contralesional cerebellum ( P = 0.027, n = 12). This was associated with reduced CBV in contralesional cerebellum ( P = 0.039, n = 9). CCD may be a useful model to determine the relative contribution of CBV to signal change measured by OCI.

scholarly journals A Useful MRI Classification for Symptomatic Discoid Lateral Meniscus

2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Eui Yub Jung ◽  
Seongmin Jeong ◽  
Sun-Kyu Kim ◽  
Sung-Sahn Lee ◽  
Dong Jin Ryu ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Lateral Meniscus ◽  
Meniscal Repair ◽  
Discoid Lateral Meniscus ◽  
Resonance Imaging ◽  
Mri Findings ◽  
Signal Change ◽  
Magnetic Resonance Imaging Mri ◽  
Arthroscopic Procedures ◽  
Group 1

Abstract Purpose The purpose of this study is to classify the discoid lateral meniscus (DLM) according to the signal and shape in magnetic resonance imaging (MRI), and to provide information not only in diagnosis but also in treatment. Materials and Methods We reviewed 162 cases who diagnosed with DLM by MRI and underwent arthroscopic procedures from April 2010 to March 2018. Three observers reviewed MRI findings of all cases and predicted arthroscopic tear using three MRI criteria (criterion 1,2 and 3). Among three criteria, the criterion that most accurately predicts arthroscopic tear was selected. Using this criterion, the cases of predicted tear were named group 1. In addition, group 1 was divided into three subgroups (group 1a, 1b and 1c) by deformation or displacement on MRI and arthroscopic type of tear and procedures were analyzed according to these subgroups. Results The intra-meniscal signal change itself (criterion 3) on MRI showed the highest agreement with the arthroscopic tear. No meniscal deformation and displacement on MRI (group 1a) showed no specific type of tear and more cases of meniscal saucerization. The meniscal deformation on MRI (group 1b) showed more simple horizontal tears and more cases of meniscal saucerization. The meniscal displacement on MRI (group 1c) showed more peripheral tears and more cases of meniscal repair and subtotal meniscectomy. Comparing arthroscopic type of tear and type of arthroscopic procedure between three subgroups, there were significant differences in three groups (P < .05). Conclusions Intra-meniscal signal change itself on MRI is the most accurate finding to predict arthroscopic tear in symptomatic DLM. In addition, subgroup analysis by deformation or displacement on MRI is helpful to predict the type of arthroscopic tear and procedures.

scholarly journals The Pathophysiology of Primary Hip Osteoarthritis may Originate from Bone Alterations

2013 ◽  
Vol 7 (1) ◽  
pp. 112-118 ◽  
Author(s):  
Mikio Kamimura ◽  
Yukio Nakamura ◽  
Shota Ikegami ◽  
Keijiro Mukaiyama ◽  
Shigeharu Uchiyama ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Proximal Femur ◽  
Hip Osteoarthritis ◽  
Pain Scale ◽  
Resonance Imaging ◽  
Mineral Density ◽  
Plain Radiographs ◽  
Signal Changes ◽  
Magnetic Resonance Imaging Mri

Objectives: The aim of this study was to investigate whether bone alterations detected by hip magnetic resonance imaging (MRI) were associated with subsequent primary hip OA. Methods: We enrolled 7 patients with hip joint pain from their first visit, at which hip joints were classified as grade 0 or I on the Kellgren-Lawrence grading scale. Plain radiographs and magnetic resonance imaging (MRI) were performed on all cases, and pain was assessed with the Denis pain scale. Average age, height, weight, body mass index, bone mineral density (L1-4), central edge angle, Sharp’s angle, and acetabular hip index were calculated. Results: Within two months of the onset of pain, 4 of the 7 cases showed broad bone signal changes, while 3 cases showed local signal changes in the proximal femur on hip MRI. Three to 6 months after the onset of pain, in all patients whose pain was much improved, plain radiographs showed progression to further-stage OA. Conclusion: Our findings suggest that bone abnormalities in the proximal femur might be involved in the pathogenesis of primary hip OA.

Abstract 107: Early Change in Ferumoxytol-Enhanced Magnetic Resonance Imaging Signal Suggests Unstable Human Cerebral Aneurysm. A Pilot Study

Stroke ◽  
2013 ◽  
Vol 44 (suppl_1) ◽  
Author(s):  
David M Hasan ◽  
donald hesitad
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Cerebral Aneurysm ◽  
Cerebral Aneurysms ◽  
Resonance Imaging ◽  
Unruptured Aneurysms ◽  
Ruptured Aneurysms ◽  
Cyclooxygenase 1 ◽  
Signal Changes ◽  
Cox 2

Background: Imaging with magnetic resonance imaging (MRI) 72 hours after infusion of ferumoxytol demonstrated maximal uptake by macrophages in the wall of human cerebral aneurysms. The clinical significance of early (i.e. within the first 24 hours) uptake of ferumoxytol by macrophages in the wall of human cerebral aneurysms is not clear. The purpose of this study was to determine whether early uptake of ferumoxytol which may indicate inflammation, suggests unstable cerebral aneurysm. Methods: 30 unruptured aneurysms in 22 patients were imaged with MRI 24 hours after infusion of ferumoxytol. Eighteen aneurysms were also imaged 72 hours after infusion of ferumoxytol. Aneurysm dome tissue was collected from four patients with early MRI signal changes, five patients with late signal changes, and five other patients with ruptured aneurysms. The tissue was immunostained for expression of cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), microsomal-prostaglandin-E2 synthase-1 (mPGES-1) and macrophages. Findings: In 23% (7/30) of aneurysms, there was pronounced early uptake of ferumoxytol. Four aneurysms were clipped. The remaining three aneurysms which were managed conservatively with observation, all ruptured within six months. In 89% (16/18) of aneurysms, there was pronounced uptake of ferumoxytol at 72 hours. Nine aneurysms were surgically clipped and nine were managed conservatively; none ruptured or increased in size in six months. With immunostaining, expression of COX-2, mPGES-1, and macrophages was similar in unruptured aneurysms with early uptake of ferumoxytol and ruptured aneurysms. Expression of these inflammatory molecules was significantly higher in aneurysms with early uptake of ferumoxytol than in aneurysms with late uptake. Interpretation: Uptake of ferumoxytol in aneurysm walls within the first 24 hours strongly suggests aneurysm instability and probability of rupture within six months, and may warrant intervention. Larger clinical studies are indicated to validate this preliminary observation.

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