Clinical application of three-dimensional anisotropy contrast magnetic resonance axonography

1999 ◽  
Vol 90 (4) ◽  
pp. 791-795 ◽  
Author(s):  
Tsutomu Nakada ◽  
Naoki Nakayama ◽  
Yukihiko Fujii ◽  
Ingrid L. Kwee
Keyword(s):  
Magnetic Resonance ◽  
Healthy Volunteers ◽  
Clinical Application ◽  
Color Image ◽  
Three Dimensional ◽  
Cerebral Peduncle ◽  
Imaging Method ◽  
Medial Lemniscus ◽  
Diffusion Weighted Images ◽  
Diffusion Weighted

✓ The utility of three-dimensional anisotropy contrast (3DAC) magnetic resonance (MR) axonography, a method sensitive to neuronal fibers and their directionality, was investigated in the clinical setting using a 3-tesla MR imaging system based on a General Electric Signa platform. The study focused on healthy volunteers and patients with common structural central nervous system disorders, namely chronic infarction, brainstem cavernous hemangioma, supratentorial meningioma, and astrocytoma. Three orthogonal anisotropic diffusion-weighted images were first obtained. Three primary colors were each assigned to a diffusion-weighted image, respectively, and the images were subsequently combined into a single-color image in full-color spectrum (3DAC MR axonography image). Fiber-tract definition in the cerebral peduncle of the midbrain of healthy volunteers showed intersubject variation, with two general patterns recognized: dispersed (60% of cases) and compact (40% of cases). Pathological alterations in the fiber tracts were readily identified in cases involving wallerian degeneration of the pyramidal tract, as illustrated in the cases of chronic infarction. Displacement of major tracts, such as the medial lemniscus or corticospinal tract, as well as fiber directionality, was also easily recognized in cases of mass lesions. As an imaging method uniquely capable of providing information regarding axonal connectivity, 3DAC MR axonography appears to have promising potential for routine clinical application.

scholarly journals ECG-gated dynamic magnetic resonance imaging method for examination of the pig heart

2001 ◽  
Vol 49 (3) ◽  
pp. 275-284
Author(s):  
Zs. Petrási ◽  
R. Romvári ◽  
G. Bajzik ◽  
B. Fenyves ◽  
I. Repa ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Three Dimensional ◽  
Dynamic Magnetic Resonance Imaging ◽  
Imaging Method ◽  
Resonance Imaging ◽  
Dynamic Magnetic Resonance ◽  
Heart Cycle ◽  
The Right

A dynamic magnetic resonance imaging (MRI) method was developed for in vivo examination of the pig heart. Measurements were carried out on 15 meat-type pigs of different liveweight using a 1.5 T equipment. Inhalation anaesthesia was applied, then data acquisition was synchronised by ECG gating. Depending on the heart rate and heart size, in each case 8 to 10 slices and in each slice 8 to 14 phases were acquired prospectively according to one heart cycle. During the post-processing of the images the left and the right ventricular volumes were determined. The values measured at 106 kg liveweight are 2.5 times higher than those obtained at 22 kg, while the ejection fractions are equal. The calculated cardiac output values were 3.5 l (22 kg, 132 beats/min.), and 6.0 l (106 kg, 91 beats/min.), respectively. After measuring the wall thickness, the contraction values were also determined for the septum (70%), and for the anterior (61%), posterior (41%) and lateral (54%) walls of the left ventricle. Three-dimensional animated models of the ventricles were constructed. Based on the investigations performed, the preconditioning, the anaesthetic procedure, the specific details of ECG measurement and the correct MR imaging technique were worked out.

Alterations in intramuscular water movement associated with mechanical changes in human skeletal muscle fibers: an evaluation using magnetic resonance diffusion-weighted imaging and B-mode ultrasonography

2011 ◽  
Vol 52 (9) ◽  
pp. 1003-1008 ◽  
Author(s):  
Osamu Yanagisawa ◽  
Toshiyuki Kurihara ◽  
Toru Fukubayashi
Keyword(s):  
Magnetic Resonance ◽  
Ankle Joint ◽  
Structural Changes ◽  
Water Movement ◽  
Morphological Changes ◽  
Muscle Fibers ◽  
Medial Gastrocnemius ◽  
Plantar Flexors ◽  
Diffusion Weighted Images ◽  
Diffusion Weighted

Background Intramuscular water movement is expected to be affected by the mechanical changes of the muscle fibers. However, the effect of changes in fiber length (FL) and pennation angle (PA) on the water movement has not been sufficiently investigated in human skeletal muscles. Purpose To determine the relationship between intramuscular water movement and the mechanical changes in human muscle fibers. Material and Methods Axial magnetic resonance diffusion-weighted images of the right leg (eight men) were taken using a 1.5-Tesla device with the ankle joint maximally dorsiflexed and maximally plantar flexed. The apparent diffusion coefficient (ADC) values of both the dorsiflexors (the superficial and deep parts of the tibialis anterior) and the plantar flexors (medial gastrocnemius and soleus) were calculated along three orthogonal axes (S-I: superior-to-inferior, A-P: anterior-to-posterior, and R-L: right-to-left). FL and PA of both muscle groups were also calculated from longitudinal B-mode ultrasound images with the ankle joint maximally dorsiflexed and plantar flexed. Results There was a significant increase in the ADC in superficial ( P < 0.05) and deeP ( P < 0.05) parts of the dorsiflexors in the S-I direction when the ankle was plantar flexed and in the A-P and R-L directions when the ankle was dorsiflexed ( P < 0.05). The plantar flexors showed significantly elevated ADC in the S-I direction when the ankle was dorsiflexed ( P < 0.05), and in the A-P and R-L directions when the ankle was plantar flexed ( P < 0.05). The dorsiflexors also showed significantly increased PA and decreased FL values when the ankle was dorsiflexed ( P < 0.05). The plantar flexors displayed similar morphological changes when the ankle was plantar flexed ( P < 0.05). Conclusion Water diffusion is affected by structural changes in the long axis of the muscle fibers, namely the changes in PA and FL.

DIFFUSION-WEIGHTED MAGNETIC RESONANCE IMAGING OF THE ULNAR NERVE IN CUBITAL TUNNEL SYNDROME

Hand Surgery ◽  
2010 ◽  
Vol 15 (01) ◽  
pp. 11-15 ◽  
Author(s):  
K. Iba ◽  
T. Wada ◽  
M. Tamakawa ◽  
M. Aoki ◽  
T. Yamashita
Keyword(s):  
Magnetic Resonance ◽  
Ulnar Nerve ◽  
Signal Intensity ◽  
Cubital Tunnel Syndrome ◽  
Cubital Tunnel ◽  
High Signal ◽  
Diffusion Weighted Mri ◽  
Diffusion Weighted Images ◽  
Diffusion Weighted ◽  
Tunnel Syndrome

Diffusion-weighted images based on magnetic resonance reveal the microstructure of tissues by monitoring the random movement of water molecules. In this study, we investigated whether this new technique could visualize pathologic lesions on ulnar nerve in cubital tunnel. Six elbows in six healthy males without any symptoms and eleven elbows in ten patients with cubital tunnel syndrome underwent on diffusion-weighted MRI. No signal from the ulnar nerve was detected in normal subjects. Diffusion-weighted MRI revealed positive signals from the ulnar nerve in all of the eleven elbows with cubital tunnel syndrome. In contrast, conventional T2W-MRI revealed high signal intensity in eight elbows and low signal intensity in three elbows. Three elbows with low signal MRI showed normal nerve conduction velocity of the ulnar nerve. Diffusion-weighted MRI appears to be an attractive technique for diagnosis of cubital tunnel syndrome in its early stages which show normal electrophysiological and conventional MRI studies.

Threshold Isocontouring on High b-Value Diffusion-Weighted Images in Magnetic Resonance Mammography

2019 ◽  
Vol 43 (3) ◽  
pp. 434-442
Author(s):  
Fangrong Zong ◽  
Sebastian Bickelhaupt ◽  
Tristan Anselm Kuder ◽  
Wolfgang Lederer ◽  
Heidi Daniel ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
B Value ◽  
Diffusion Weighted Images ◽  
High B Value ◽  
Diffusion Weighted ◽  
Magnetic Resonance Mammography

Correlation of Placental Magnetic Resonance Imaging With Histopathologic Diagnosis: Detection of Aberrations in Structure and Water Diffusivity

2019 ◽  
Vol 23 (4) ◽  
pp. 260-266
Author(s):  
Crystal Bockoven ◽  
Roland D Gastfield ◽  
Thomas Victor ◽  
Palamadai N Venkatasubramanian ◽  
Alice M Wyrwicz ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Unknown Etiology ◽  
Placental Pathology ◽  
Resonance Imaging ◽  
Fixed Tissue ◽  
Diffusion Weighted Images ◽  
Diffusion Weighted ◽  
And Diffusion

Objective Noninvasive methods to identify placental pathologic conditions are being sought in order to recognize these conditions at an earlier stage leading to improved clinical interventions and perinatal outcomes. The objective of this study was to examine fixed tissue slices of placenta by T2- and diffusion-weighted magnetic resonance imaging (MRI) and correlate the images with placental pathologic findings defined by routine gross and histologic examination. Methods Four formalin-fixed placentas with significant placental pathology (maternal vascular malperfusion, chronic villitis of unknown etiology, and massive perivillous fibrin deposition) and 2 histologically normal placentas were evaluated by high-resolution MRI. Representative placental slices were selected (2 cm long and 10 mm wide) and rehydrated. Imaging was performed on a Bruker Avance 14.1 T microimager. Diffusion-weighted images were acquired from 16 slices using slice thickness 0.5 mm and in-plane resolution approximately 100 µm × 100 µm. T2 maps were obtained from the same slices. T2 relaxation time and apparent diffusion coefficient (ADC) were acquired from representative regions of interest and compared between normal and diseased placentas. Results In T2- and diffusion-weighted images, the placental microstructure differed subjectively between diseased and normal placentas. Furthermore, diseased placentas showed statistically significantly longer mean T2 relaxation times and generally higher mean ADC. Conclusion Diffusion- and T2-weighted MRI can potentially be used to detect significant placental pathology by using T2 relaxation time and ADC as markers of altered placental microstructure.

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