Analysis of skeletal-muscle condition after excessive loading of the lower legs by sequential magnetic resonance imaging.

OBJECTIVES: To determine the changes of muscle conditions of lower leg after stretch shortening cycle exercises by MRI. SUBJECTS AND METHODS: This study included 20 healthy male adult volunteers. After conducting control MRI, each subject performed 3 sets of exercise loading, each set consisting of 100 repetitions of rebound jumping on one foot. MRIs were performed immediately after exercise loading (0 h), 6, 30, and 168 h later. After constructing T1/T2/Fractional Anisotropy (FA)/Apparent Diffusion Coefficient (ADC) maps, the changes of three skeletal muscles of the leg (the tibialis anterior [TA], soleus [SOL], and gastrocnemius [GA]) were quantitatively evaluated in each map at each time point. RESULTS: The T1 and T2 values were prolonged after exercise loading, and there was a delay in the recovery of T1 at 6 and 30 h after exercise loading, as compared to those of T2 values over time. The ADC values were elevated in all three muscles immediately after exercise loading, then recovered more slowly than T1 and T2, and still had not returned to baseline 168 h after exercise loading. The FA value decreased in all three muscles after exercise loading, with the greatest decrease occurring immediately after exercise loading. As with the ADC values, the FA values were slow to recover from the decrease, and had not returned to baseline levels 168 h post-loading. CONCLUSION: The delay of T1 value recovery suggested that the T1 value may reflect the muscle condition like fatigue and damage. Changes in the ADC and FA values over time suggested that structural changes such as minute muscular injuries can be detected by diffusion-weighted MRI. Meanwhile, the changes observed in the T1 and T2 values suggested that the measured relaxation time data reflected not only the water volume in the muscle, but also the muscle condition after exercise loading.

Operative Strategies during Awake Surgery Affect Deterioration of Paresis a Month after Surgery for Brain Lesions in the Primary Motor Area.

Introduction We analyzed factors associated with worsened paresis at 1-month follow-up in patients with brain tumors located in the primary motor area (M1) to establish protocols for safe awake craniotomy for M1 lesions. Methods Patients with M1 brain tumors who underwent awake surgery in our hospital (n = 61) were evaluated before, during, and immediately and 1 month after surgery for severity of paresis, tumor location, extent of resection, complications, preoperative motor strength, histology, and operative strategies (surgery stopped or continued after deterioration of motor function). Results Worsened paresis at 1-month follow-up was significantly associated with worsened paresis immediately after surgery and also with operative strategy. Specifically, when motor function deteriorated during awake surgery and did not recover within 5 to 10 minutes, no deterioration was observed at 1-month follow-up in cases where we stopped surgery, whereas 6 of 13 cases showed deteriorated motor function at 1-month follow-up in cases where we continued surgery. Conclusion Stopping tumor resection on deterioration of motor function during awake surgery may help prevent worsened paresis at 1-month follow-up.

Associations among q-space MRI, diffusion-weighted MRI and histopathological parameters in meningiomas.

OBJECTIVES: The purposes of this MR-based study were to calculate q-space imaging (QSI)-derived mean displacement (MDP) in meningiomas, to evaluate the correlation of MDP values with apparent diffusion coefficient (ADC) and to investigate the relationships among these diffusion parameters, tumour cell count (TCC) and MIB-1 labelling index (LI). METHODS: MRI, including QSI and conventional diffusion-weighted imaging (DWI), was performed in 44 meningioma patients (52 lesions). ADC and MDP maps were acquired from post-processing of the data. Quantitative analyses of these maps were performed by applying regions of interest. Pearson correlation coefficients were calculated for ADC and MDP in all lesions and for ADC and TCC, MDP and TCC, ADC and MIB-1 LI, and MDP and MIB-1 LI in 17 patients who underwent subsequent surgery. RESULTS: ADC and MDP values were found to have a strong correlation: r = 0.78 (P = <0.0001). Both ADC and MDP values had a significant negative association with TCC: r = -0.53 (p = 0.02) and -0.48 (P = 0.04), respectively. MIB-1 LI was not, however, found to have a significant association with these diffusion parameters. CONCLUSION: In meningiomas, both ADC and MDP may be representative of cell density. KEY POINTS: • Diffusion-weighted MRI offers possibilities to assess the aggressiveness of meningiomas. • The q-space imaging-derived mean displacement correlates strongly with apparent diffusion coefficients. • Both diffusion parameters showed a strong negative association with tumour cell counts. • Derived mean displacement may help assess the aggressiveness of meningiomas preoperatively.

Damage to the left ventral, arcuate fasciculus and superior longitudinal fasciculus-related pathways induces deficits in object naming, phonological language function and writing, respectively.

The anatomic localization of brain functions can be characterized via diffusion tensor imaging in patients with brain tumors and neurological symptoms. The goal of the present study was to evaluate the function of the ventral, arcuate fasciculus (AF) and the superior longitudinal fasciculus (SLF)-related language pathways using these techniques by analyzing 9 patients treated in our hospital between 2007 and 2011. In cases 1-3, the left ventral pathways, namely, the inferior longitudinal fasciculus, uncinate fasciculus or inferior fronto-occipital fasciculus, were mainly damaged, and the common dysfunction experienced by these patients was a deficit in object naming. In cases 4-6, the left SLF was mainly damaged, and the common deficit was dysgraphia. In cases 7-9, the left AF was mainly damaged, and almost all language functions related to phonology were abnormal. These results suggest that the left ventral, AF and SLF-related pathways are closely related to visual, auditory and hand-related language function, respectively.

Awake craniotomy for brain lesions within and near the primary motor area: A retrospective analysis of factors associated with worsened paresis in 102 consecutive patients.

BACKGROUND: We analyzed factors associated with worsened paresis in a large series of patients with brain lesions located within or near the primary motor area (M1) to establish protocols for safe, awake craniotomy of eloquent lesions. METHODS: We studied patients with brain lesions involving M1, the premotor area (PMA) and the primary sensory area (S1), who underwent awake craniotomy (n = 102). In addition to evaluating paresis before, during, and one month after surgery, the following parameters were analyzed: Intraoperative complications; success or failure of awake surgery; tumor type (A or B), tumor location, tumor histology, tumor size, and completeness of resection. RESULTS: Worsened paresis at one month of follow-up was significantly associated with failure of awake surgery, intraoperative complications and worsened paresis immediately after surgery, which in turn was significantly associated with intraoperative worsening of paresis. Intraoperative worsening of paresis was significantly related to preoperative paresis, type A tumor (motor tract running in close proximity to and compressed by the tumor), tumor location within or including M1 and partial removal (PR) of the tumor. CONCLUSIONS: Successful awake surgery and prevention of deterioration of paresis immediately after surgery without intraoperative complications may help prevent worsening of paresis at one month. Factors associated with intraoperative worsening of paresis were preoperative motor deficit, type A and tumor location in M1, possibly leading to PR of the tumor.

Characteristics of diffusion-weighted stimulated echo pulse sequence in human skeletal muscle.

The aim of our study was to simulate an effective diffusion-weighted imaging (DWI) pulse sequence and to evaluate the best b value in skeletal muscle. The evaluated pulse sequences were spin echo (SE), stimulated echo (STE), and gradient-recalled echo (GRE). The signal intensity changed in some DWI pulse sequences when the b value was changed. Moreover, the static magnetic field of 1.5 T was compared with that of 3.0 T. Next, diffusion tensor imaging of the human skeletal muscle was measured. The experimental subjects were healthy male volunteers (n = 7; age 21.8 ± 1.1 years). We changed the b value in steps of 100 s/mm(2) from 0 to 2000 s/mm(2), and the diffusion values [fractional anisotropy (FA), λ(1), λ(2), and λ(3)] were calculated based on the data. The STE method could maintain signals up to b values of 1300 s/mm(2), but the SE and GRE methods suffered from high noise. In the human study, the mean FA (±SD) was 0.41 ± 0.02 in the tibialis anterior muscle (TA) and 0.31 ± 0.02 in the soleus muscle (SOL) at a b value of 1000 s/mm(2). The correlation of the FA with the b value coefficient and the P value by Student's t test were r = 0.981 and P < 0.001 for the TA and r = 0.982, P < 0.001 for the SOL. However, the FA became high with a low b value. In conclusion, STE was very useful for DWI in a short T (2)-value tissue. Moreover, a minimum b value of 800 s/mm(2) was necessary for evaluation of human skeletal muscle.

Age-related white matter changes in high b-value q-space diffusion-weighted imaging.

INTRODUCTION: To assess and compare age-related diffusion changes in the white matter in different cerebral lobes, as quantified by diffusion-weighted imaging (DWI) and high b-value q-space imaging (QSI). METHODS: Seventy-three cases without neurological symptoms or imaging abnormalities were grouped by age as young (<30 years, n = 20), middle-aged (30-49 years, n = 19), old (50-69 years, n = 18), and very old (> 70 years, n = 16) and imaged by a 1.5-T MR scanner for DWI and QSI. Apparent diffusion coefficient (ADC) and mean displacement (MDP) values were calculated in the white matter of frontal, parietal, and temporal lobes and compared using Dunnett's test, with the young group as a control. RESULTS: MDP values in frontal and parietal lobes were significantly higher in old and very old age groups than in the young, while those in the temporal lobes were significantly higher only in the very old group. ADC values were significantly higher in all three lobes in the very old group. CONCLUSION: QSI is more sensitive than DWI to age-related myelin loss in white matter.

Diffusion fractional anisotropy-based transformation in skeletal muscle caused by pressure.

PURPOSE: We used diffusion tensor imaging (DTI) to evaluate anisotropic changes in skeletal muscle cells under external pressure. MATERIALS AND METHODS: In 6 healthy volunteers, we compared DTI of the tibialis anterior (TA) and soleus (SOL) muscles under pressure. We performed imaging using a 1.5-tesla magnetic resonance (MR) scanner and diffusion-weighted stimulated-echo echo-planar pulse sequences optimized for skeletal muscle. We calculated diffusion tensor eigenvalues (λ), apparent diffusion coefficients, and fractional anisotropy (FA) values in a series of axially acquired DTI and compared them between the pressurized and nonpressurized lower limbs. We also measured a cross-sectional area of skeletal muscle. RESULTS: We observed clear differences in FA and λ3 between pressurized muscles and the nonpressurized muscles we used as controls. The mean control FAs were 0.36±0.02 (TA) and 0.30±0.02 (SOL). The mean control λ3s were 0.74±0.02 s/mm² (TA) and 0.85±0.03 s/mm² (SOL). FA values in the pressurized (200 mmHg) limbs increased to 0.39±0.02 (TA) and 0.35±0.04 (SOL) compared with those values in the nonpressurized controls. λ3 values in the pressurized (200 mmHg) limbs decreased to 0.68±0.05 s/mm² (TA) and 0.77±0.06 s/mm² (SOL) compared with those in controls. Moreover, the mean value of cross-sectional area of skeletal muscle (control) was 907.3±140.1 mm² (TA) and 1522±201.0 mm² (SOL). The cross-sectional area in the pressurized (200 mmHg) limbs decreased to 590.3±68.1 mm² (TA) and 1131±112.6 mm² (SOL) compared with those in controls. One-way analysis of variance (ANOVA) and post hoc Tukey-Kramer tests showed significant differences. CONCLUSION: Anisotropy changed markedly on pressurizing the lower limb based on the correlation of the cross-sectional area and λ3 suggested marked changed in anisotropy following application of pressure to the lower limb. If compression of the cross-sectional area is assumed to represent compression of the cell, change in λ3 reflected the change in the size of muscle cells.

The left superior longitudinal fasciculus within the primary sensory area of inferior parietal lobe plays a role in dysgraphia of kana omission within sentences.

Functional neurological changes after surgery combined with diffusion tensor imaging (DTI) tractography can directly provide evidence of anatomical localization of brain function. Using these techniques, a patient with dysgraphia before surgery was analyzed at our hospital in 2011. The patient showed omission of kana within sentences before surgery, which improved after surgery. The brain tumor was relatively small and was located within the primary sensory area (S1) of the inferior parietal lobe (IPL). DTI tractography before surgery revealed compression of the branch of the superior longitudinal fasciculus (SLF) by the brain tumor. These results suggest that the left SLF within the S1 of IPL plays a role in the development of dysgraphia of kana omission within sentences.

High b-value q-space analyzed diffusion-weighted MRI using 1.5 tesla clinical scanner; determination of displacement parameters in the brains of normal versus multiple sclerosis and low-grade glioma subjects.

PURPOSE: We aimed to determine the displacement parameters in the brains of normal individuals relative to brain parenchymal abnormalities, such as multiple sclerosis (MS) and low-grade glioma, by q-space imaging (QSI) using 1.5-T magnetic resonance (MR) scanner. MATERIALS AND METHODS: Thirty-five normal, three pathologically proven low-grade glioma, and five MS subjects were imaged by a 1.5-T MR unit for QSI (b-values, 0-12,000 s/mm(2)). Mean displacement (MD) values in white matter (WM), gray matter (GM), and lateral ventricle (cerebrospinal fluid [CSF]) of normal subjects, plaques, and normal appearing WM (NAWM) of MS subjects and glioma lesions were calculated. Mann-Whitney U test was used for comparison. RESULTS: In normal subjects, MD values were 6.6 ± 0.2, 8.44 ± 0.41, and 17.08 ± 0.80 µm for WM, GM, and CSF, respectively, while those for NAWM and WM plaques in MS, and glioma lesions were significantly higher at 7.0 ± 0.17, 9.3 ± 2.3, and 9.6 ± 0.40 µm, respectively, compared to WM in normal subjects. CONCLUSION: We propose that the relative values of MD obtained by QSI in control and diseased tissues can be useful for diagnosing various WM abnormalities.

Right temporal lobe plays a role in verbal memory.

OBJECTIVES: Comparison of preoperative and postoperative neurological functions in patients undergoing resection of brain tumors, in combination with data from diffusion tensor imaging (DTI) studies, can provide direct evidence of anatomical localization of brain function. The goal of the present study was to use these techniques to characterize memory function of the right temporal lobe in five patients with right temporal lobe brain tumors. METHODS: Memory function was tested using the Wechsler Memory Scale-Revised (WMS-R) before and after surgery in five patients with right temporal lobe brain tumors. Preoperative DTI was performed in four of five cases. RESULTS: In all cases, general and verbal memory, including verbal paired association, significantly improved after surgery (P<0.05). The right inferior longitudinal fasciculus (ILF) was compressed by the tumor in all cases. CONCLUSION: These results suggest that the right temporal lobe plays a role in verbal memory and that this function may be associated with the right ILF.

A comparison of mean displacement values using high b-value Q-space diffusion-weighted MRI with conventional apparent diffusion coefficients in patients with stroke.

RATIONALE AND OBJECTIVES: Q-space analysis using high b-value diffusion-weighted magnetic resonance (MR) data provides information on tissue microstructure in contrast to conventional MR imaging (MRI) based on low b-value diffusion-weighted imaging (DWI). The purpose of this study was to evaluate the use of mean displacement (MDP) map in stroke patients using q-space diffusion-weighted MRI (QSI). MATERIALS AND METHODS: Twenty-one patients presenting with a total of 22 acute or subacute cerebral infarctions were included. MR protocol consisted of conventional MR sequences, DWI (b-value; 1000 s/mm(2)) and QSI (b-value; maximum 12,000 s/mm(2)). Apparent diffusion coefficient (ADC) maps of conventional DWI and MDP maps of QSI data were obtained and compared in the ischemic lesions and corresponding normal tissues. RESULTS: Decreased ADC values were present in all lesions. There was no correlation between ADC and MDP values in the lesions (r = 0.21). MDP values of the lesions were 8.60 ± 1.26 µm (mean ± SD). Most of the lesions (16/22) had higher MDP values than normal brain tissue. Three lesions showed lower MDP values and three showed mixed MDP values. CONCLUSIONS: The MDP maps using QSI data provides additional information for stroke patients compared to conventional DWI.

Advantages and disadvantages of awake surgery for brain tumours in the primary motor cortex: institutional experience and review of literature.

Patients undergoing awake surgery for resection of brain tumours in the primary motor cortex (M1) are at high risk of developing new motor deficits. Thus, use of this procedure requires consideration of several important points, including the optimal modality to localise M1 on the affected side and the overall advantages and disadvantages of the procedure. In our experience with awake surgery for 21 brain tumours located in the M1 from January 2004 through October 2008, we found that functional magnetic resonance imaging was the most reliable modality in terms of localising the M1 and that the anatomic relationship between motor tracts and brain tumours is a critical determinant of postoperative motor function. Other considerations, including potential complications of this procedure and relative efficacy and safety versus surgery under general anaesthesia for patients with brain tumours in the M1, are discussed.

Damage to the upper portion of area 19 and the deep white matter in the left inferior parietal lobe, including the superior longitudinal fasciculus, results in alexia with agraphia.

Analysis of lesions and symptoms in patients with brain tumors combined with information from diffusion tensor imaging provides direct evidence of the anatomical localization of brain function. Using these methods, we evaluated 8 patients who underwent surgery for metastatic brain tumors located in the left occipital lobes between 2007 and 2009. Preoperatively, 4 patients (cases 1-4) had alexia with agraphia while the other 4 patients (cases 5-8) did not. Tractography for the superior longitudinal fasciculus (SLF) was performed before surgery in case 1. The common brain tumors in cases 1-4 were located in the upper portion of area 19, and peritumor edema in that area resulted in compromise of the deep white matter of the inferior parietal lobe (IPL). The SLF was compressed and disrupted in the white matter of the IPL near the upper portion of area 19 in case 1. In cases 5-8, the brain tumors were not located in the upper portion of area 19. These results suggest that damage to the upper portion of area 19 and to the white matter in the left IPL, including the SLF, resulted in alexia with agraphia.

Damage of left temporal lobe resulting in conversion of speech to Sutra, a Buddhist prayer stored in the right hemisphere.

The present study describes a case of a right-handed 74-year-old woman with a brain tumor who showed conversion of speech to Sutra, a Buddhist prayer, which was stored in the right hemisphere according to the Wada test. After surgery, relative improvement in the speech disorder was observed, and frequency of speech production of simple normal words with normal phonology increased. These observations indicate that damage to left temporal lobe resulted in conversion of speech to Sutra, and that Sutra was stored in this patient's right hemisphere.

Relationships between brain tumor and optic tract or calcarine fissure are involved in visual field deficits after surgery for brain tumor.

PURPOSE: Diffusion tensor tractography provides useful information regarding the surgical strategy for brain tumors. The goal of the present study was to analyze relationships between visual field deficits and the locations of brain tumors compared with optic tracts as visualized by tractography, and compared with the calcarine fissure. METHODS: Subjects comprised 11 patients with brain tumor in the occipital lobe or atrium of the lateral ventricle who underwent surgery between October 2006 and February 2009. Tumors were categorized as Type A, with almost all the optic tract in the occipital lobe or atrium of the lateral ventricle running close to and stretched by the brain tumor; and Type B, with the optic tract running at least partially distant to the brain tumor and remaining unstretched. RESULTS: Those type A optic tracts that were laterally compressed by brain tumors (Cases 1-3) displayed hemianopsia after surgery. When the brain tumor was located rostro-medial to the calcarine fissure and optic tracts were compressed caudally by the tumor, lower quadrant hemianopsia remained after surgery (Cases 4, 5). In other cases, the visual field remained or improved to normal after surgery. CONCLUSION: The relationship between optic tracts or the calcarine fissure, and brain tumors in the occipital lobe or atrium of the lateral ventricle is related to visual field deficits after surgery. In particular, those Type A optic tracts that are compressed laterally show hemianopsia of the visual field after surgery.

Deficits in the left inferior longitudinal fasciculus results in impairments in object naming.

The functional characteristics of the left inferior longitudinal fasciculus (ILF) remain unclear. The present study describes a case of a right-handed 74-year-old woman with a brain tumor who showed marked deterioration in object naming ability after invasion of the tumor into the medial region of the left posterior (middle and inferior) temporal lobe just beside the atrium of the lateral ventricle. Diffusion tensor imaging showed possible interruption of the left ILF after invasion of tumor at this site. By contrast, the left superior longitudinal fasciculus (SLF) remained intact after invasion of tumor, and the inferior fronto-occipital fasciculus (IFOF) was already disrupted prior to tumor invasion. These observations indicate that intact ILF function may be required for object naming ability.

Combined movement of multi-joint muscles activates a smaller area compared to the sum of areas activated by respective single-joint muscles after restoration of paresis.

Awake surgery provides accurate localization of brain function based on rapid reversible neurological changes during surgical manipulation. In this study, hand clenching rapidly deteriorated due to surgical manipulation during awake surgery and instantly recovered not by hand clenching alone but by combined movement of hand clenching and elbow flexion. Postoperative fMRI (functional MRI) showed a smaller area activated by combined movement of hand clenching and elbow flexion than the sum of areas activated by hand clenching alone and elbow flexion alone. Conversely, the activated area by combined movement of hand clenching and elbow flexion was almost the same as the sum of areas by hand clenching alone and elbow flexion alone in fMRI of normal volunteers. These findings indicate reorganization of the motor area by combined movement including the motor function of previous transient weakness, and might suggest the effectiveness of combined movement to improve motor paresis in rehabilitation.