High-resolution MRI of cranial nerves in posterior fossa at 3.0 T

OBJECTIVE@#To evaluate the influence of high-resolution imaging obtainable with the higher field strength of 3.0 T on the visualization of the brain nerves in the posterior fossa.@*METHODS@#In total, 20 nerves were investigated on MRI of 12 volunteers each and selected for comparison, respectively, with the FSE sequences with 5 mm and 2 mm section thicknesses and gradient recalled echo (GRE) sequences acquired with a 3.0-T scanner. The MR images were evaluated by three independent readers who rated image quality according to depiction of anatomic detail and contrast with use of a rating scale.@*RESULTS@#In general, decrease of the slice thickness showed a significant increase in the detection of nerves as well as in the image quality characteristics. Comparing FSE and GRE imaging, the course of brain nerves and brainstem vessels was visualized best with use of the three-dimensional (3D) pulse sequence.@*CONCLUSIONS@#The comparison revealed the clear advantage of a thin section. The increased resolution enabled immediate identification of all brainstem nerves. GRE sequence most distinctly and confidently depicted pertinent structures and enables 3D reconstruction to illustrate complex relations of the brainstem.

Longitudinal follow-up of patients with mild traumatic brain injury by magnetic resonance spectroscopic technique

OBJECTIVE@#To explore the changes in the concentrations of neural markers immediately or several months after mild traumatic brain injury (mTBI).@*METHODS@#The metabolic markers of neurons in white matter tissues above the lateral ventricle were semi-quantitatively determined by employing 1H magnetic resonance spectroscopic technique (1-H-MRS) in 30 clinically diagnosed cases of mTBI. At the same time, the neurological functions of the subjects, including ability to pay attention, memory, working memory and operational capacity etc were also assessed.@*RESULTS@#The patients were followed up for, on average, 13 days after mTBI and the results showed that Cre, PCre and Glx in the white matter tissues were significantly elevated in mTBI patients. 17 patients (57%) recovered from the injury during the follow-up (median was defined as the 40th post-trauma day). Comparison in terms of intelligence among groups revealed that the levels of neural markers of intelligence development was positively related with intelligence scores).@*CONCLUSIONS@#Change in Glx concentrations is most sensitive during trauma or in ensuing repairing processes, and might be different from normal status in the following months and Glx level tends to be accompanied with change in Cre, another energy-related marker.

Comparison between magnitude reconstruction and phase-sensitive mR imaging in the detection of myocardial infarction

OBJECTIVE@#To determine the deference between phase sensitive magnetic resonance (MR) imaging and magnitude reconstruction to detect infracted myocardium.@*METHODS@#Twenty patients (16 men; 4 women; mean age, 56 years). experienced Q-wave myocardial infarction 2 weeks earlier were examined with a 3.0-T MR system 10 minutes after administration of 0.1 mmol/kg body weight gadobenate dimeglumine. To determine the optimal TI, a TI scout sequence was used. A segmented 2D IR true fast imaging with steady-state precession (trueFISP) sequence that produces both phase-sensitive and magnitude-reconstructed images were used at TI values of 200-600 msec (TI values were varied in 100-msec steps) and at optimal TI (mean value, 330 msec). Contrast-noise ratios (CNRs) of normal and infarcted myocardium and the area of infarcted myocardium were determined. Two-tailed unpaired sample Student t test was used to compare CNRs, and area of infarction.@*RESULTS@#MMean CNR phase-sensitive and magnitude-reconstructed images at optimal TI (mean value, 330 msec) were 6.2, and 6.1, respectively. For a TI of 200 msec, CNR values were 5.5, and 4.2, respectively; for TI of 600 msec, CNR values were 5.8 and 4.3, respectively. Area of infarcted myocardium was underestimated on magnitude-reconstruction images (P = 0.002-0.03) for short TI values (ie., 200 msec) but not on phase sensitive reconstructed when compared with IR tureFISP images obtained at optimal TI.@*CONCLUSIONS@#LPhase-sensitive image reconstruction results in reduced need for precise choice of TI and more consistent image quality.

Delay enhancement patterns in apical hypertrophic cardiomyopathy by phase-sensitive inversion recovery sequence

OBJECTIVE@#Late gadolinium enhancement (LGE) patterns of cardiovascular magnetic resonance (CMR) relying on PSIR (phase-sensitive inversion recovery sequence) techniques had been used to determine the characteristics of LGE in apical hypertrophic cardiomyopathy (ApHCM).@*METHODS@#Forty patients pure ApHCM [age, (60.2±10.4) years, 31 men] were enrolled. LGE images were acquired using PSIR, and analyzed using a 17-segment model. Summing the LGE areas in all short axis slices yielded the total volume of late enhancement, which was subsequently presented as a proportion of total LV myocardium (% LGE).@*RESULTS@#Mean maximal apical wall thickness was (17.9±2.3) mm, and mean left ventricular (LV) ejection fraction was (67.7±8.0)%. LGE was detected in 130 segments of 30 patients (75.0%), occupying (4.9±5.5)% of LV myocardium. LGE was mainly detected at the junction between left and right ventricles in 12 (30%) and at the apex in 28 (70%), although LGE-positive areas were widely distributed, and not limited to the apex. Focal LGE at the non-hypertrophic LV segments was found in some ApHCM patients, even without LGE of hypertrophied apical segments.@*CONCLUSIONS@#LGE was frequently observed not only in the thickened apex of the heart but also in other LV segments, irrespective of the presence or absence of hypertrophy. The simple presence of LGE on CMR was not representative of adverse prognosis in this population.

Structural abnormalities of trigeminal root with neurovascular compression revealed by high resolution diffusion tensor imaging

OBJECTIVE@#To detect neurovascular compression-induced structural abnormalities of trigeminal nerves (TGN) by diffusion tensor imaging (DTI).@*METHODS@#The affected ipsilateral TGN (iTGN) and unaffected contralateral TGN (cTGN) of 20 trifacial neuralgia (TN) patients as well as the bilateral TGN of 10 normal controls (nTGN) were examined by DTI and 3D high resolution MRI using a 3.0 T MRI scanner. The fractional anisotropy and apparent diffusion coefficient (ADC) were determined.@*RESULTS@#Compared with the cTGN and nTGN, the iTGN had significantly lower fraction of anisotropy (FA), significantly higher ADC, and significantly smaller volume and cross-sectional area (P<0.05).@*CONCLUSIONS@#The increase in ADC and decrease in FA has a close relationship with morphological changes of TGN, and the DTI could provide valuable diagnostic information on TGN structure for TN patients.