Magnetic resonance imaging (MRI) of pituitary adenomas

MRI of 20 patients, 17-82 years old, with pituitary adenomas confirmed histopathologically, and 30 normal patients without pituitary dysfunction were reviewed. The studies were performed with a 0.5 Tesla MR scanner with a slice thickness of 10 mm. Inversion recovery sequences were employed as T 1-weighted examination, with repetition time (TR) of 2100-2500 msec, an inversion time (TI) of 600 msec and an echo time (TE) of 40 msec. The T 2-weighted examination had a TR of 1800-2500 msec and a TE of 120 msec. T 1-weighted images were obtained in all cases and T 2-weighted images in 14 cases. Spin echo images with a TR of 600-1000 msec and a TE of 40 msec (SE 40/600-1000) were also obtained in 14 cases. On T 1-weighted images, 20 adenomas were classified into six groups, according to their signal intensities; marked low intensity (1), low intensity (1), isointensity (11), high intensity (3), marked high intensity (1) and mixed intensity (3). On T 2-weighted images, 14 adenomas were classified into five groups; low intensity (1), isointensity (2), high intensity (4), marked high intensity (6) and mixed intensity (1). On SE 40/600-1000 images, 14 adenomas were also classified into four groups; low intensity (8), high intensity (2) and mixed intensity (3). Two adenomas with recent intratumoral hemorrhage had marked high intensity on both T1 and T2-weighted images. SE 40/600-1000 images were useful in evaluating the size and the extent of the visual pathway was best appreciated on IR images. Comparison between normal and involved cavernous sinus by adenomas was made.     

Magnetic resonance imaging (MRI) of intracranial chordomas

MR images of 5 patients with intracranial chordoma were evaluated and compared with those of other clival lesions (1 clival osteomyelitis, 1 metastatic clival tumor, 3 clival meningiomas). The MR examination was performed using a 0.5 T superconductive magnet, with approximately 10 mm section thickness, one average and a 256 x 256 matrix. T1 weighted images were obtained by inversion recovery (IR) with TR 2100-2500 msec, TI 600 msec and TE 40 msec. T2 weighted images were obtained by spin echo pulse sequence with TR 1800-2500 msec and TE 120 msec (long SE). In several cases, the spin echo pulse sequences with TR 1000 msec and TE 40 msec (short SE) were also done. Multiplaned images were obtained. Four of 5 intracranial chordomas were low in intensity compared to cerebral gray matter on T1 weighted images, and all of 5 chordomas were as high in intensity as cerebrospinal fluid or higher than that of cerebrospinal fluid on T2 weighted images. Clival fatty marrow is high intensity on T1 weighted images. Clival involvement by a tumor was a clearly demonstrated as disappearance of this high intensity in all cases. In two cases, the tumor extended to the retropharyngeal space and this was detected clearly on short SE image. Although clival fatty marrow was disappeared, osteomyelitis and metastatic tumor in clivus were iso-intense to cerebral gray matter on both T1 and T2 weighted images.(ABSTRACT TRUNCATED AT 250 WORDS)     

Spinal subdural empyema diagnosed by MRI and recovered by conservative treatment

Localized suppuration involving the spinal cord is uncommon. A case of spinal subdural empyema is reported. The patient is 54-year-old male who had been suffering a diabetes mellitus but did not receive any treatment. His initial symptom was lumbago. Then he noticed a palpitation and general malaise which made him visit a hospital. Because he did not show any improvement by a fluid therapy, he was transferred to our institute for the further evaluation. On admission, physical examination showed no abnormality. Blood pressure was 170/90 mmHg, heart rate 128/min. and body temperature 37.1 degrees C suggesting a septic shock state. Neurological examination revealed slight consciousness disturbance, mild tetraparesis and bilateral hypesthesia lower than the level of L3. Laboratory examination showed the elevated leukocyte count and fasting blood sugar and urine ketone body levels of 20,500/mm3, 257 mg/dl and 226 mg/dl respectively. Blood culture proved a septicemia of Streptococcus agalactiae afterwards. On the second day of admission, lumbar puncture revealed a purulent cerebrospinal fluid, though X-ray CT of lumbar spine did not confirm a diagnosis. Spinal magnetic resonance imaging (MRI) revealed a widespread abnormal intensity of the spinal canal from the level of Th11 to L4. On the T1-weighted image (TR 300 msec., TE 40 msec.), cerebrospinal fluid space was abnormally isointense. On the T2-weighted image (TR 2,000 msec., TE 80 msec.), subdural and cerebrospinal space was filled with an abnormal high-intense lesion especially on the ventral side. He developed semicoma due to hydrocephalus following a intraventricular empyema. He was also complicated disseminated intravascular coagulation.(ABSTRACT TRUNCATED AT 250 WORDS)     

The preliminary experience of MRI diagnoses in multiple sclerosis: a report of 3 cases

In this report, 3 patients with suspected MS were studied by MRI. All patients were performed with spin-echo (SE) pulse sequence. A pulse repetition time (TR) of 1800 msec. and echo time (TE) of 33, 66, 99, 132 msec. producing a T2-weighted image. The result showed that MS is characterized by numerous long T2 lesions in the paraventricular white matter. Brain stem lesions were seed in all 3 patients. MRI is a very useful diagnostic tool for diagnosis of MS.     

Magnetic resonance imaging of experimental cerebral ischemia: correlations between NMR parameters and water content

Recent studies on proton NMR imaging revealed its remarkable sensitivity for detecting cerebral ischemia. Since proton NMR reflects the distribution and state of water in the brain, an NMR imager becomes a sensitive in vivo detector of brain edema developing soon after the energy state is compromized by ischemia. To further clarify the usefulness of NMR imaging to characterize the ischemia-induced changes, correlations between T1 and T2 relaxation times and water content of the normal and ischemic rat and gerbil brain were studied by means of both spectroscopic and in vivo imaging methods. In the spectroscopic experiment on excised rat brain (cortex, white matter, hippocampus and thalamus for normal and ischemia-laden brain), T1 and T2 relaxation times and water content were determined. The ischemic insult was induced for 60 min by the method of Pulsinelli followed by 60 min of reperfusion. All of the T1, T2 and water content significantly increased in the ischemic tissue. Gray-white difference was evident in T1 and T1 was linearly correlated with the water content of the tissue. T2 was by far prolonged in the ischemic tissue compared with the increase in the water content, showing greater sensitivity of T2 for detection of ischemia. In the imaging experiment, coronal NMR imaging at 0.5 tesla was performed employing proton density-weighted saturation recovery (TR = 1.6 s, TE = 14 ms), T1-weighted inversion recovery (TR = 1.6 s, TI = 300 ms, TE = 14 ms) and T2-weighted spin echo (TR = 1.6 s, TE = 106 ms) pulse sequences.(ABSTRACT TRUNCATED AT 250 WORDS)     

White matter hyperintensity in neurologically asymptomatic subjects

Recent advances in magnetic resonance imaging (MRI) technology have had a great impact on the delectability of minute, asymptomatic lesions of the central nervous system. The clinical significance and treatment modes of these lesions, such as white matter hyperintensity (WMH) lesions detected by T2 MRI, remain controversial. To address these problems, we retrospectively evaluated WMH lesions in relation to clinical parameters for 240 neurologically asymptomatic persons who had visited a hospital for a medical check-up of the brain. Proton and T2–weighted MRI were obtained using a 0.5 T superconducting MR imager using the spin echo technique with a repetition time (TR) of 2800 msec. An echo delay times (TE) of 40 msec was used for the proton MRI, and a TE of 100 msec was used for the T2-weighted MRI. The images were visually analyzed according to a four-point grading system. The MRI findings were correlated with clinical parameters including age, gender, presenting symptoms, and hypertension. The overall frequency of WMH increased with age. Grades 2 and 3 of WMH were more frequent in aged persons, whereas the occurrence of grade 1 WMH remained relatively constant across age groups. Based on multiple regression analysis, age was the most significant variable influencing the frequency of WMH, followed by hypertension. These results imply that WMH lesions may simply be a phenomenon of aging, or may be an indicator of prepathologic state in an ischemic brain.     

Vertebral hemangioma with extradural spinal cord compression. Clinico-radiologic and NMR findings

A haemangioma extending from the first thoracal vertebra into the extradural spinal canal presented clinically as slowly progressive incomplete cord compression. Radiographic, myelographic, and CT findings are demonstrated and an additional lumbar vertebral haemangioma was found. The study of magnetic resonance imaging (MRI) done by spin-echo technique indicated that signal intensities within the vascular malformation measured in various recovery (TR) and echo times (TE) are largely the result of different blood flow velocities.     

Use of fluid-attenuated inversion recovery (FLAIR) images in brain check-up]

Fluid-attenuated inversion recovery (FLAIR) images are magnetic resonance (MR) images obtained with an inversion recovery sequence having a long inversion time (T 1) and a long echo time (TE). The purpose of this study was to evaluate the utility of FLAIR images in brain check-up. 320 healthy adults (229 males, 91 females) were examined with FLAIR sequences of several types having repetitive time (TR) of 7000 msec, inversion times of 1700 msec and echo times (TE) of 110 msec. All studies were performed on a SHIMAZU MAGNEX 100 HP 1.0 T imaging system. FLAIR images were useful in detecting cortical and subcortical lesions near the brain surface, which were unclear in the conventional T 2 weighted images. FLAIR images were useful in evaluation of periventricular hyperintensity area (PVH). Frequency and degree of PVH were increased in aging. FLAIR images were useful in the differential diagnosis of lacuna and perivascular space. In conclusion, FLAIR images were very sensitive for the detection of brain lesions in brain check-up.     

Visualization of the IXth to XIIth Cranial Nerves Using 3-Dimensional Constructive Interference in Steady State, 3-Dimensional Magnetization-Prepared Rapid Gradient Echo and T2-Weighted 2-Dimensional Turbo Spin Echo Magnetic Resonance Imaging Sequences

OBJECTIVE: The purpose of this study was to evaluate the visibility of the IXth to XIIth cranial nerves using different magnetic resonance sequences. Thirty healthy volunteers underwent magnetic resonance imaging at 1.5 T using 3-dimensional constructive interference in steady state (CISS) sequence (TR = 17 ms, TE = 8.08 ms, alpha = 70 degrees), 3-dimensional magnetization-prepared rapid gradient echo (MP-RAGE) sequence (TR = 11.08 ms, TE = 4.3 ms, alpha = 15 degrees), and T2-weighted (w) 2-dimensional turbo spin echo (TSE) sequence (TR = 4000 ms, TE = 102 ms, alpha = 180 degrees, slice thickness = 2 mm). Visibility of the IXth to XIIth cranial nerves in each sequence was evaluated by consensus of 2 radiologists using an evaluation scale from 1 (excellently visible) to 5 (not visible). A correlation with anatomic specimens was made. The 3-dimensional CISS sequence provides best resolution of the IXth to XIIth cranial nerves and their relation to surrounding structures. Additional information is given by the 3-dimensional MP-RAGE when nerves are surrounded by soft tissues. Using the T2w 2-dimensional TSE sequence, even whole nerves cannot be visualized due to intersection gap and partial volume effects. However, even in 3-dimensional high-resolution sequences, segments of nerves are not always visualized. A combination of 3-dimensional CISS and 3-dimensional MP-RAGE proved to be useful to visualize the IXth to XIIth cranial nerves, whereas the 2-dimensional technique failed. Further investigations using 3-dimensional MP-RAGE with contrast medium should be performed in the case of abnormality.     

Asymptomatic spinal cord lesions in clinically isolated optic nerve, brain stem, and spinal cord syndromes suggestive of demyelination

OBJECTIVES—Conventional T2 weighted MRI studieshave highlighted the fact that the presence of clinically silent brainlesions increases the risk of developing clinically definite multiplesclerosis after an isolated syndrome of the optic nerve, brain stem, or spinal cord. The objectives of the present study are: (1) to show whether or not these patients also have asymptomatic abnormalities ofthe spinal cord, and (2) to recruit a new cohort of such patients usinghigh resolution MRI of both brain and spinal cord.
METHODS—The brain was imaged in the axial planewith 3 mm thick contiguous slices using a proton density and T2weighted fast spin echo (FSE) sequence; a T1 weighted sequence afterthe injection of gadolinium-DTPA; and a fast fluid attenuated inversionrecovery (fFLAIR) sequence. The spinal cord was imaged in the sagittal plane with 3 mm thick slices using a T2 weighted FSE and a T1 weightedgadolinium enhanced sequence.
RESULTS—Thirty three patients, meanage 31 (16-46) were recruited. There were 14 men and 19 women. BrainMRI was abnormal in 22 (67%); no patient was seen with abnormalitieson only one or other sequence. Six patients (18%)displayed one or more gadolinium enhancing lesions on brain MRI. In thespinal cord, nine (27%) patients displayed one or more clinicallysilent lesions on FSE. Two patients showed one and two gadoliniumenhancing lesions in the spinal cord respectively.
CONCLUSION—This high incidence of spinal cordlesions emphasises that asymptomatic demyelinating lesions may alsoinvolve clinically eloquent pathways. Follow up studies are required todetermine their prognostic importance.

     

Simultaneous functional magnetic resonance imaging in the rat spinal cord and brain

Functional magnetic resonance imaging (fMRI) method was developed to investigate the pattern and temporal relationship in neuronal pathways of brain and spinal cord. Signal intensity changes correlating with stimulation patterns were observed simultaneously in the rat spinal cord and brain using fMRI at 9.4 T. Electrical stimulation of the forepaw was used to elicit activity. A quadrature volume RF coil covering both brain and the cervical spinal cord was used. Sets of fast spin echo (FSE) images were acquire simultaneously for both brain and spinal cord fMRI. Experiments were repeated in single animal and across animals. Activities within the dorsal horn of the spinal cord and within the somatosensory cortex were observed consistently within each animal as well as across animals.     

Magnetic resonance imaging and laterobulbar infarction

Six patients with a clinical diagnosis of lateral medullary infarction have been studied by CT scan and Magnetic Resonance Imaging (MRI). The MRI study was performed on a CGR Magniscan 5000 with a superconducting magnet of 5 Tesla. In all patients T2 weighted images (TR = 2000, TE 60, 120) in joined section of 9 or 6 mm thickness were obtained in the axial plane. Three patients were also studied in T1 weighted sequences (TR = 500, TE = 28). A lateral medullary infarct was shown in 5 patients. MRI findings were consistent with a hemorrhagic infarct in one case. Occlusion of a vertebral artery was suggested in 2 cases and was confirmed by angiography. In 3 cases, an associated ipsilateral cerebellar infarct was demonstrated. The CT scan had only shown bleeding in the medulla oblongata in the hemorrhagic infarction case, and a cerebellar infarction in another case. Some clinical manifestations are discussed with regard to the results of MRI. MRI appears as the best current method to improve clinico-topographic correlations in medullary infarcts.     

"Dynamic" MR imaging of the cervical cord in patients with cervical spondylosis and ossification of the posterior longitudinal ligament--significance of dynamic cord compression]

This investigation was designed to assess the influence of dynamic cord compression on severity and course of myelopathy. Sixty-seven patients studied comprised 54 cases of cervical spondylosis and 13 cases of ossification of the posterior longitudinal ligament. These patients underwent "dynamic" MR imaging of the cervical spine. MR images in the sagittal view were obtained in three different neck positions: flexion, neutral, and extension. MR imaging was performed with a 0.15 T resistive unit. For technical reasons, the body coil was used. The pulse sequence was 500/30 (Tr msec/echo time msec) for T1 images. The spinal cord compression was accelerated in 32 cases when extended, in 2 cases when flexed, and in 4 cases when both extended and flexed. In 21 cases, we compared myelograms with MR images in a same neck position. Findings of myelograms well corresponded with those of MR images on 83 percent of intervertebral levels. The patients with dynamic cord compression were proved to have severer long tract signs, and their disability was regressive or progressive case by case for an average of 21-month follow-up. The "dynamic" MR imaging can provide dynamic nature of spinal cord compression, and prognostic clues.     

7‐T MRI of the spinal cord can detect lateral corticospinal tract abnormality in amyotrophic lateral sclerosis

Introduction: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder affecting lower and upper motor neurons. Degeneration of the lateral corticospinal tract (CST) is a key finding in ALS cervical spinal cord autopsies. We hypothesized that in vivo ultra‐high‐field MRI of the cervical spinal cord can detect abnormality in the CST. Methods: A patient with ALS (disease duration 23 months) and a healthy control were scanned at 7‐T MRI using a 19‐channel coil. Multi‐echo ‐weighted imaging was performed in the spinal cord, covering C2–C6. Cross‐sectional resolution was 0.37 × 0.37 mm². Results: We detected clear signal hyperintensity in both segments of the lateral CST in the ALS patient, which was significant when compared with the normal control subject (P < 10^?7). Conclusion: We believe there are potential benefits of 7‐T MRI for increased sensitivity and spatial accuracy in characterizing pathology in the spinal cord. Muscle Nerve 47: 760–762, 2013     

Deep white matter hyperintensity in occipital lobe on T2 weighted magnetic resonance imaging

Magnetic resonance imaging (MRI) was performed in 270 patients with various neurologic complaints (1-15 Y) with a 0.5 tesla superconducting imaging system (MRT-50 A, Toshiba Co.) using a field echo sequence (TR/TE: 300 ms/14 ms) and a spine echo sequence (TR/TE: 2,000 ms/100 ms or 2,000 ms/120 ms, and 2,000 ms/30 ms). The slice thickness was 10 mm. Hyperintensity areas on T2-weighted images were noted at the occipital lobe in 33 patients (12.2%). Twenty-seven of them had hyperintensity within the deep white matter, which revealed iso- or hypointensity on T1-weighted images. The diagnosis for the 27 patients included medulloblastoma after multidisciplinary therapy (1), congenital heart disease (1), neurofibromatosis (1), tuberous sclerosis (1), congenital muscular dystrophy (1), congenital myotonic dystrophy (2), febrile convulsion (2), autism (3), epilepsy (9) and unknown causes (6). Because the hyperintensity areas are age-dependent, they may result from delayed myelination in the central nervous system.     

Diffusion-weighted MRI of spinal cord infarction

Infarction is a rare cause of spinal cord dysfunction. Whereas diffusion-weighted (DW) MRI has been established as a highly sensitive technique for assessing acute cerebral ischemia, its role in spinal cord infarction remains to be determined. The purpose of this study is to present the signal characteristics of acute spinal cord ischemia using DWMRI within the first two days and after one week. MRI including DW imaging (DWI) was performed in three patients with acute spinal cord dysfunction 8, 12 and 30 hours after the onset of symptoms and repeated after one week in two patients. Two initial scans included EPI DW sequences in transverse and sagittal orientation. The remaining examinations were performed with an optimised high-spatial resolution DWI sequence in the transverse plane. The diagnosis of spinal cord ischemia was established by imaging, clinical history and CSF analysis. T2 signal abnormality and restricted diffusion was demonstrated in all initial examinations. Transverse DW sequences had the highest sensitivity. The spinal infarctions were mainly located in the centre of the spinal cord and the grey matter. Contrast enhancement was absent. After one week, the restricted diffusion had normalised (pseudo normalisation) whereas the T2 signal changes had become more prominent. Restricted diffusion in the course of spinal cord ischemic infarction can be demonstrated using DW-MRI. Whereas a diffusion abnormality can be found after few hours, it does not last for longer than one week. At this time, the establishment of the diagnosis has to rely mainly on T2-weighted images with additional post contrast T1-weighted images being useful.     

Dynamic contrast-enhanced susceptibility-weighted perfusion MRI (DSC-MRI) in a glioma model of the rat brain using a conventional receive-only surface coil with a inner diameter of 47 mm at a clinical 1.5 T scanner

Magnetic resonance (MR) imaging in animal models is usually performed in expensive dedicated small bore animal scanners of limited availability. In the present study a standard clinical 1.5 T MR scanner was used for morphometric and dynamic contrast-enhanced susceptibility-weighted MR imaging (DSC-MRI) of a glioma model of the rat brain. Ten male Wistar rats were examined with coronal T2-weighted, and T1-weighted images (matrix 128 x 128, FOV 64 mm) after implantation of an intracerebral tumor xenografts (C6) using a conventional surface coil. For DSC-MRI a T2*-weighted sequence (TR/TE=30/14 ms, matrix 64 x 64, FOV 90 mm; slice thickness of 1.5mm) was performed. Regions of interest were defined within the tumor and the non-affected contralateral hemisphere and the mean transit time (MTT) was determined. Tumor dimensions in MR predicted well its real size as proven by histology. The MTT of contrast agent passing through the brain was significantly decelerated in the tumor compared to the unaffected hemisphere (p<0.001, paired t-test), which is most likely due to the leakage of contrast agent through the disrupted blood brain barrier. This setup offers advanced MR imaging of small animals without the need for dedicated animal scanners or dedicated custom-made coils.     

Delayed radiation necrosis of the temporal lobe following radiation therapy of maxillary carcinoma

A case of delayed radiation necrosis following radiation therapy for maxillary carcinoma was reported. The diagnosis of this case for the radiation necrosis was clinically suggestive and established by the pathological findings of autopsy. This 66 year-old man had been treated by the partial resection for the right maxillary carcinoma with chemotherapy (pepleomycin 110 mg, adriamycin 20 mg). Pre- and postoperatively total dose of 5040 rads were irradiated with cobalt therapy during 42 days at a dose of 180 rads and 5 times in a week through two ports at 8 x 8 cm field including right orbital region. Three years 7 months after radiation therapy he complained of disorientation, recent memory disturbance and slight left hemiparesis. On enhanced CT irregular ring enhanced mass lesion was seen in left temporal lobe inside the radiation field with extensive low density over temporal lobe on plain CT. MR imaging demonstrated that T 1-weighted spin echo images with a 50-msec repetition time (TR) and 22-msec echo time (TE) had irregular low signal intensity and extensive high signal intensity combined with partially low intensity in the central area on T2 weighted spin echo images with 2300 msec TR and 100 msec TR. There were not appeared vascular obstruction and stenosis on right carotid angiogram. He improved remarkably on clinical symptoms and CT by treating of dexamethasone and osmotic diuretics, but died of pneumonia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Brain and spinal cord MRI in motor neuron disease.

Motor neuron disease causes widespread degeneration of motor neurons within both the brain and spinal cord. Brain and spinal cord MRI were performed in 11 patients with motor neuron disease, and in 17 controls. Symmetric areas of high signal within the corticospinal tracts were found in nine patients on T2 weighted spin echo (SE) or fast spin echo (FSE) images of the brain and in eight on T2 or T2* weighed images of the spinal cord. High signal within the posterior limbs of the internal capsules was also found in four controls; this finding in isolation is therefore not pathological. No controls had abnormalities within the spinal cord. Low signal within the motor cortex was found in 10 patients, but was also seen in six controls. Thus MRI often displays characteristic abnormalities within the corticospinal tracts in patients with motor neuron disease, and should be considered in the investigation of suspected cases.     

Magnetically evoked EMGs in rats

Magnetic stimulation of the brain and spinal cord was carried out in rats to record electromyogram (EMGs) from the gastrocnemius. A figure-eight coil was set over the middle of the dorsum, and shifted from the cervical vertebrae to the sacrum. The motor evoked potentials (MEPs) with 4.8 msec latency by transcranial magnetic stimulation and the descending wave with 4.7 msec latency by C3-C4 stimulation were recorded. In evoked EMGs by magnetic stimulation over T9-T10, L4-L5, S2-S3 and Ca2-Ca3 spinal cord levels, the causes of these two evoked components with short (1.5 msec) and long (4.1 msec) latencies were estimated to be the eddy current generated from the rostral to the caudal portion of the spinal cord. With the increase in magnetic stimuli, the relative sizes and disappearance of H- and M-like responses were comparable with the ordinary M- and H-responses in electrically evoked EMGs. The magnetic stimulation of the spinal cord activated the sciatic nerve at their vertebral exit, because the latencies of the H- and M-responses were constant despite the changing stimulus sites. Although magnetic stimulation with the figure-eight coil can be focused on the target, it is necessary to take into consideration the influence of the eddy current flowing in the body.