Discriminant analysis using MRI asymmetry indices and cognitive scores of women with temporal lobe epilepsy or schizophrenia.

PURPOSE: This study aims to assess the diagnostic power of brain asymmetry indices and neuropsychological tests for differentiating mesial temporal lobe epilepsy (MTLE) and schizophrenia (SCZ). METHODS: We studied a total of 39 women including 13 MTLE, 13 SCZ, and 13 healthy individuals (HC). A neuropsychological test battery (NPT) was administered and scored by an experienced neuropsychologist, and NeuroQuant (CorTechs Labs Inc., San Diego, California) software was used to calculate brain asymmetry indices (ASI) for 71 different anatomical regions of all participants based on their 3D T1 MR imaging scans. RESULTS: Asymmetry indices measured from 10 regions showed statistically significant differences between the three groups. In this study, a multi-class linear discriminant analysis (LDA) model was built based on a total of fifteen variables composed of the most five significantly informative NPT scores and ten significant asymmetry indices, and the model achieved an accuracy of 87.2%. In pairwise classification, the accuracy for distinguishing MTLE from either SCZ or HC was 94.8%, while the accuracy for distinguishing SCZ from either MTLE or HC was 92.3%. CONCLUSION: The ability to differentiate MTLE from SCZ using neuroradiological and neuropsychological biomarkers, even within a limited patient cohort, could make a substantial contribution to research in larger patient groups using different machine learning techniques.

Microsurgical management of midbrain gliomas: surgical results and long-term outcome in a large, single-surgeon, consecutive series.

OBJECTIVE: The authors report on a large, consecutive, single-surgeon series of patients undergoing microsurgical removal of midbrain gliomas. Emphasis is put on surgical indications, technique, and results as well as long-term oncological follow-up. METHODS: A retrospective analysis was performed of prospectively collected data from a consecutive series of patients undergoing microneurosurgery for midbrain gliomas from March 2006 through June 2022 at the authors' institution. According to the growth pattern and location of the lesion in the midbrain (tegmentum, central mesencephalic structures, and tectum), one of the following approaches was chosen: transsylvian (TS), extreme anterior interhemispheric transcallosal (eAIT), posterior interhemispheric transtentorial subsplenial (PITS), paramedian supracerebellar transtentorial (PST), perimedian supracerebellar (PeS), perimedian contralateral supracerebellar (PeCS), and transuvulotonsillar fissure (TUTF). Clinical and radiological data were gathered according to a standard protocol and reported according to common descriptive statistics. The main outcomes were rate of gross-total resection; extent of resection; occurrence of any complications; variation in Karnofsky Performance Status score at discharge, 3 months, and last follow-up; progression-free survival (PFS); and overall survival (OS). RESULTS: Fifty-four patients (28 of them pediatric) met the inclusion criteria (6 with high-grade and 48 with low-grade gliomas [LGGs]). Twenty-two tumors were in the tegmentum, 7 in the central mesencephalic structures, and 25 in the tectum. In no instance did the glioma originate in the cerebral peduncle. TS was performed in 2 patients, eAIT in 6, PITS in 23, PST in 16, PeS in 4, PeCS in 1, and TUTF in 2 patients. Gross-total resection was achieved in 39 patients (72%). The average extent of resection was 98.0% (median 100%, range 82%-100%). There were no deaths due to surgery. Nine patients experienced transient and 2 patients experienced permanent new neurological deficits. At a mean follow-up of 72 months (median 62, range 3-193 months), 49 of the 54 patients were still alive. All patients with LGGs (48/54) were alive with no decrease in their KPS score, whereas 42 showed improvement compared with their preoperative status. CONCLUSIONS: Microneurosurgical removal of midbrain gliomas is feasible with good surgical results and long-term clinical outcomes, particularly in patients with LGGs. As such, microneurosurgery should be considered as the first therapeutic option. Adequate microsurgical technique and anesthesiological management, along with an accurate preoperative understanding of the tumor's exact topographic origin and growth pattern, is crucial for a good surgical outcome.

Microsurgical and fiber tract anatomy of the interthalamic adhesion.

OBJECTIVE: The authors of this study aimed to define the microanatomy of the interthalamic adhesion (ITA) using microfiber dissection, magnetic resonance (MR) tractography, and histological analysis. METHODS: Sagittal, coronal, and axial MR images from 160 healthy individuals 2-82 years of age were examined. The relationships between age range and ITA morphology as well as between gender and ITA morphology were evaluated statistically. Among these 160 individuals, 100 who had undergone MR tractography were examined. In this group, the presence of fiber tracts in the ITA and the relationship with ITA morphological types were examined. Thirty formalin-fixed human cadaveric brains were also examined endoscopically, and 6 hemispheres were dissected from the medial to lateral and superior to inferior directions under the microscope. Sections taken from one of the brains with an ITA type 2 with both thalami were examined histologically. Anti-neurofilament antibody was used in the histological examination. RESULTS: Four morphological types of ITA were observed. Type 1 had an adhesion/adherent appearance, type 2 had a bridge/commissure appearance, type 3 showed no adhesion, and type 4 had a double bridge. Tractographic examination revealed that 28% had no fiber tract transition in the ITA, 21% had a significant transition, and 51% had an indistinct transition. Statistically, the presence of the ITA was significantly higher in the pediatric (age) and female (gender) groups. In specimens with ITAs of a bridge/commissure appearance (type 2), fiber tracts showed clear transitions between thalami. In type 1 (adherent/adhesive appearance), fiber tracts were observed within the ITA, but a reciprocal transition was unclear. Dissection showed that these fiber tracts in the ITA reach the nucleus accumbens, caudate nucleus, and frontoorbital region anteriorly and the lateral habenula and posterior commissure posteriorly. Some fibers also joined the ansa peduncularis. In histological studies, axonal fibers moving in the ITA were observed with anti-neurofilament antibody staining. CONCLUSIONS: This is the first study to demonstrate fiber tracts of the ITA through fiber dissection and transillumination techniques as well as radiological and histological study. Statistical data were obtained by comparing the morphological group with age and gender groups. The anatomy of this structure, which has been neglected for many years, was reexamined. This study showed that the ITA has fibers connecting different parts of the brain, in contrast to previous studies suggesting that it was a simple massa.

Identifying overall survival in 98 glioblastomas using VASARI features at 3T.

PURPOSE: This study aims to evaluate qualitative and quantitative imaging metrics along with clinical features affecting overall survival in glioblastomas and to classify them into high survival and low survival groups based on 12, 19, and 24 months thresholds using machine learning. METHODS: The cohort consisted of 98 adult glioblastomas. A standard brain tumor magnetic resonance (MR) imaging protocol, was performed on a 3T MR scanner. Visually Accessible REMBRANDT Images (VASARI) features were assessed. A Kaplan-Meier survival analysis followed by a log-rank test and multivariate Cox regression analysis were used to investigate the effects of VASARI features along with the age, gender, the extent of resection, pre- and post-KPS, ki67 and P53 mutation status on overall survival. Supervised machine learning algorithms were employed to predict the survival of glioblastoma patients based on 12, 19, and 24 months thresholds. RESULTS: Tumor location (p<0.001), the proportion of non-enhancing component (p=0.0482), and proportion of necrosis (p=0.02) were significantly associated with overall survival based on Kaplan-Meier analysis. Multivariate Cox regression analysis revealed that increases in proportion of non-enhancing component (p=0.040) and proportion of necrosis (p=0.039) were significantly associated with overall survival. Machine-learning models were successful in differentiating patients living longer than 12 months with 96.40% accuracy (sensitivity=97.22%, specificity=95.55%). The classification accuracies based on 19 and 24 months survival thresholds were 70.87% (sensitivity=83.02%, specificity=60.11%) and 74.66% (sensitivity=67.58%, specificity=82.08%), respectively. CONCLUSION: Employing clinical and VASARI features together resulted in a successful classification of glioblastomas that would have a longer overall survival.

Cingulate sulcus morphology and paracingulate sulcus variations: Anatomical and radiological studies.

The sulci and gyri found across the cerebrum differ in morphology between individuals. The cingulate sulcus is an important landmark for deciding the surgical approach for neighboring pathological lesions. Identifying the anatomical variations of anterior cingulate cortex morphology would help to determine the safe-entry route through neighboring lesions. In this study, magnetic resonance imaging data acquired from 149 healthy volunteers were investigated retrospectively for anatomical variations of the paracingulate sulcus. Also, human cadaveric brain hemispheres were investigated for cingulate and paracingulate sulcus anatomy. All participants had cingulate sulci in both hemispheres (n = 149, 100%). Three types of paracingulate sulcus patterns were identified: "prominent," "present," and "absent." Hemispheric comparisons indicated that the paracingulate sulcus is commonly "prominent" in the left hemisphere (n = 48, 32.21%) and more commonly "absent" in the right hemisphere (n = 73, 48.99%). Ten (6.71%) people had a prominent paracingulate sulcus in both the right and left hemispheres. Seven (4.70%) of them were male, and 3 (2.01%) of them were female. Paracingulate sulci were present in both hemispheres in 19 people (12.75%), of which 9 (6.04%) were male and 10 (6.71%) were female. There were 35 (23.49%) participants without paracingulate sulci in both hemispheres. Eleven (7.38%) were male and 24 (16.11%) were female. There were 73 (48.99%) participants without right paracingulate sulcus and 57 (38.26%) participants without left paracingulate sulcus (p = 0.019). In the examinations of the cadaver hemispheres, the paracingulate sulcus was present and prominent in 25%, and the intralimbic sulcus was present in 15%. It has been observed that the paracingulate sulcus is more prominent in the normal male brain compared to females. In females, there were more participants without paracingulate sulcus. This study shows that there are both hemispheric and sex differences in the anatomy of the paracingulate sulcus. Understanding the cingulate sulcus anatomy and considering the variations in the anterior cingulate cortex morphology during surgery will help surgeons to orient this elegant and complex area.

Menstrual Cycle-Related Changes in Women with Schizophrenia: A Resting-State fMRI Study.

INTRODUCTION: Different influences of ovarian hormones in schizophrenia (SCZ) have been reported, but no study to date has assessed their effects on the brain dynamics at rest. The present study aimed to examine the hormonal and clinical changes related to the menstrual cycle and alterations in the resting-state functional connectivity (RS-FC) depending on cycle phase and/or hormonal fluctuations in SCZ. METHOD: This study was conducted based on both between- and within-subject experimental designs, including 13 clinically stable female patients with SCZ (32 ± 7.7 years) and 13 healthy women (30 ± 7.3 years). RS-functional magnetic resonance imaging (fMRI) scanning, as well as hormonal and clinical assessments, was applied to each participant twice during two cycle phases: early follicular and mid-luteal. RESULTS: A difference in mid-luteal progesterone levels was found between groups, with a large effect size (Cohen's d) of 0.8 (p < 0.05). Also, the estradiol levels negatively correlated with the negative symptom severity of the patients during their mid-luteal phase. In the patients, estrogen positively correlated with the auditory network connectivity in the left amygdala during the early follicular phase. In the controls, progesterone had positive correlations with the connectivity of the posterior default mode and the left frontoparietal networks in the bilateral precuneus during the early follicular phase and had a negative correlation with the executive control network connectivity in the mid-luteal phase. CONCLUSION: The present study showed hormonal differences between groups and suggested that the levels of cycle-dependent hormones might be associated with the changes in clinical symptom severity and the RS-FC in the groups. Our RS-fMRI findings warrant further investigation.

The posterior interhemispheric transparieto-occipital fissure approach to the atrium of the lateral ventricle: a fiber microdissection study with case series.

The surgical approach to the atrium of the lateral ventricle remains a challenge because of its deep location and close relationship to important neurovascular structures. We present an alternative and safer approach to lesions of the atrium using a natural pathway through the parieto-occipital fissure. We demonstrate this approach through cadaveric anatomical microdissection and a case series. Five formalin-fixed brain specimens (10 hemispheres) were dissected with the Klingler technique. Transillumination was used to show the trajectory of the approach in cadaveric specimens. Clinical data from five patients who underwent this approach were reviewed. This data included intraoperative ultrasound images, operative images, pre- and postoperative magnetic resonance imaging, MR tractography, and visual field examination. The parieto-occipital fissure is a constant, uninterrupted fissure that can be easily identified in cadavers. Our anatomical dissection study revealed that the atrium of the lateral ventricle can be approached through the parieto-occipital fissure with minor damage to the short association fibers between the precuneus and cuneus, and a few fibers of the forceps major. In our series, five patients underwent total resection of their atrial lesions via the posterior interhemispheric transparieto-occipital fissure. No morbidity or mortality was observed, and the disruption of white matter was minimal, as indicated on postoperative tractography. The postoperative visual fields were normal. The posterior interhemispheric transparieto-occipital fissure approach is an alternative to remove lesions in the atrium of the lateral ventricle, causing the least damage to white matter tracts and preserving visual cortex and optic radiation.

Limited positive predictive value of diffusion tensor tractography in determining clinically relevant white matter damage in brain stem cavernous malformations: A retrospective study in a single center surgical cohort.

PURPOSE: Diffusion tensor tractography (DTT) might reflect the postoperative clinical outcome of the patients with brain stem (BS) tumors correlating well with the neurological symptoms, but cavernous malformation (CM) is a hemorrhagic tumor prone to artifacts that may limit DTT. We set out to determine the correlation of DTT findings with the neurological examination before and after surgical resection in patients with BSCMs. MATERIALS AND METHODS: DTT findings were evaluated bilaterally for fiber tract displacement or deviation, deformation and interruption in every patient before and after the surgery. Neurological examination was performed at admission, discharge and outpatient follow-up visit. The sensitivity, specificity, positive and negative predictive values of DTT were calculated both pre- and post-operatively. RESULTS: There were 25 patients (9 men 16 women) with a mean age of 39.5±13.9 years. The mean size of the CMs was 6909±8374mm3 (range: 180-38,220mm3) The mean follow-up time was 42.7±23.2 months (range: 8 to 112 months). Preoperatively, the sensitivity, specificity, positive and negative predictive values of DTT for corticospinal tracts (CST) and medial lemnisci (ML) were 100%, 60%, 38.4%, 100% and 87.5%, 11.7%, 31.8%, 66.6%, respectively. Postoperatively, the sensitivity, specificity, positive and negative predictive values of DTT for CSTs and ML were 100%, 64.7%, 40%, 100% and 100%, 0%, 33.3%, 66.6%, respectively. CONCLUSION: Positive findings on DTT such as fiber tract deviation, deformation, disruption or interruption should be taken cautiously before drawing conclusions of a clinically relevant damage of white matter tracts.

Machine-learning in grading of gliomas based on multi-parametric magnetic resonance imaging at 3T.

OBJECTIVE: The objective of this study was to assess the contribution of multi-parametric (mp) magnetic resonance imaging (MRI) quantitative features in the machine learning-based grading of gliomas with a multi-region-of-interests approach. MATERIALS AND METHODS: Forty-three patients who were newly diagnosed as having a glioma were included in this study. The patients were scanned prior to any therapy using a standard brain tumor magnetic resonance (MR) imaging protocol that included T1 and T2-weighted, diffusion-weighted, diffusion tensor, MR perfusion and MR spectroscopic imaging. Three different regions-of-interest were drawn for each subject to encompass tumor, immediate tumor periphery, and distant peritumoral edema/normal. The normalized mp-MRI features were used to build machine-learning models for differentiating low-grade gliomas (WHO grades I and II) from high grades (WHO grades III and IV). In order to assess the contribution of regional mp-MRI quantitative features to the classification models, a support vector machine-based recursive feature elimination method was applied prior to classification. RESULTS: A machine-learning model based on support vector machine algorithm with linear kernel achieved an accuracy of 93.0%, a specificity of 86.7%, and a sensitivity of 96.4% for the grading of gliomas using ten-fold cross validation based on the proposed subset of the mp-MRI features. CONCLUSION: In this study, machine-learning based on multiregional and multi-parametric MRI data has proven to be an important tool in grading glial tumors accurately even in this limited patient population. Future studies are needed to investigate the use of machine learning algorithms for brain tumor classification in a larger patient cohort.

Neighborhood resolved fiber orientation distributions (NRFOD) in automatic labeling of white matter fiber pathways.

Accurate digital representation of major white matter bundles in the brain is an important goal in neuroscience image computing since the representations can be used for surgical planning, intra-patient longitudinal analysis and inter-subject population connectivity studies. Reconstructing desired fiber bundles generally involves manual selection of regions of interest by an expert, which is subject to user bias and fatigue, hence an automation is desirable. To that end, we first present a novel anatomical representation based on Neighborhood Resolved Fiber Orientation Distributions (NRFOD) along the fibers. The resolved fiber orientations are obtained by generalized q-sampling imaging (GQI) and a subsequent diffusion decomposition method. A fiber-to-fiber distance measure between the proposed fiber representations is then used in a density-based clustering framework to select the clusters corresponding to the major pathways of interest. In addition, neuroanatomical priors are utilized to constrain the set of candidate fibers before density-based clustering. The proposed fiber clustering approach is exemplified on automation of the reconstruction of the major fiber pathways in the brainstem: corticospinal tract (CST); medial lemniscus (ML); middle cerebellar peduncle (MCP); inferior cerebellar peduncle (ICP); superior cerebellar peduncle (SCP). Experimental results on Human Connectome Project (HCP)'s publicly available "WU-Minn 500 Subjects + MEG2 dataset" and expert evaluations demonstrate the potential of the proposed fiber clustering method in brainstem white matter structure analysis.

A new MRI grading system for chondromalacia patellae.

Background Chondromalacia patellae is a very common disorder. Although magnetic resonance imaging (MRI) is widely used to investigate patellar cartilage lesions, there is no descriptive MRI-based grading system for chondromalacia patellae. Purpose To propose a new MRI grading system for chondromalacia patellae with corresponding high resolution images which might be useful in precisely reporting and comparing knee examinations in routine daily practice and used in predicting natural course and clinical outcome of the patellar cartilage lesions. Material and Methods High resolution fat-saturated proton density (FS PD) images in the axial plane with corresponding T2 mapping images were reviewed. A detailed MRI grading system covering the deficiencies of the existing gradings has been set and presented on these images. Two experienced observers blinded to clinical data examined 44 knee MR images and evaluated patellar cartilage changes according to the proposed grading system. Inter- and intra-rater validity testing using kappa statistics were calculated. Results A descriptive and detailed grading system with corresponding FS PD and T2 mapping images has been presented. Inter-rater agreement was 0.80 (95% confidence interval [CI], 0.71-0.89). Intra-rater agreements were 0.83 (95% CI, 0.74-0.91) for observer A and 0.79 (95% CI, 0.70-0.88) for observer B (k-values). Conclusion We present a new MRI grading system for chondromalacia patellae with corresponding images and good inter- and intra-rater agreement which might be useful in reporting and comparing knee MRI examinations in daily practice and may also have the potential for using more precisely predicting prognosis and clinical outcome of the patients.

Diffusion Tensor Imaging of the Uterine Zones Related to the Menstrual Cycle and Menopausal Status at 3 Tesla MRI.

BACKGROUND: Diffusion and diffusion tensor imaging techniques (DTI) are widely available and used both in central nervous system and body imaging, including gynecological diseases. AIMS: The aims of this study were to assess the capability of DTI of uterine zones in relation to the menstrual cycle and ascertain the normal apparent diffusion coefficient and fractional anisotropy values at 3T magnetic resonance imaging (MRI). STUDY DESIGN: Prospective clinical study. METHODS: A total of 13 young reproductive and 12 postmenopausal healthy volunteers were included in the study. MRI examination included sagittal T2-weighted and single-shot echo planar imaging DTI obtained under free breathing. Fractional anisotropy (FA) values of the endometrium, junctional zone, and myometrium were determined. RESULTS: The median (minimum-maximum) FA of the endometrium, myometrium, and junctional zone of the reproductive group were 0.31 (0.260-0.465), 0.42 (0.302-0.664), and 0.58 (0.420-0.745), respectively, in the proliferative phase and 0.26 (0.180-0.413), 0.48 (0.357-0.656), and 0.59 (0.490-0.675)], respectively, in the secretory phase. In the postmenopausal group, the FA values of the endometrium, myometrium, and junctional zone were 0.275 (0.136-0.425), 0.255 (0.191-0.553), and 0.27 (0.129-0.397), respectively. Apparent diffusion coefficient (ADC) values of the endometrium, myometrium, and junctional zone of the reproductive group were 1.25±0.254 (0.970-1.463), 1.67 (1.213-1.854), and 1.23 (0.853-1.301), respectively, in the proliferative phase and 1.32±0.283 (1.165-1.706), 1.55 (1.360-1.791), and 1.17 (1.163-1.705), respectively, in the secretory phase. In the postmenopausal group, the ADC values of the endometrium, myometrium, and junctional zone were measured as 1.100±0.192 (0.850-1.302), 1.14 (0.864-1.283), and 1.09 (0.912-1.291). The FA values of the endometrium and myometrium were lower in the secretory phase of the reproductive group, while ADC values were higher. However, both the FA and ADC values were lower in the postmenopausal group. CONCLUSION: The present study showed that uterine DTI is feasible when used quantitatively. While FA values tend to decrease, ADC values increase significantly in all zones in the secretory phase except the junctional zone. Zonal FA and ADC values of postmenopausal women are lower in comparison to those in young women.

Evaluating the importance of the tentorial angle in the paramedian supracerebellar-transtentorial approach for selective amygdalohippocampectomy.

OBJECTIVE: A challenging step of the paramedian supracerebellar-transtentorial approach is to expose the anterior portion of the mediobasal-temporal region (MTR), a step that seems most affected by the steepness of the tentorium. The objective of this study was to define magnetic resonance imaging measurements that can predict the level of challenge in exposing the anterior portion of the MTR. METHODS: Cranial magnetic resonance imaging studies of 100 healthy individuals were examined. The tentorial and occipital angles were measured, and the amount of brain tissue that remained hidden on the microscopic view in front of the petrous apex was indirectly estimated. These measurements were statistically compared with the cephalic index of each person. RESULTS: The mean values for the tentorial and occipital angles were 42° (range 25°-53°) and 98° (range 69°-122°), respectively. The results proved that the higher the tentorial angle, the higher the occipital angle and the greater the amount of hidden brain tissue. Of 100 persons, 3 (3%) were found to be dolichocephalic, 23 (23%) were mesocephalic, and 74 (74%) were brachycephalic. Statistical analysis proved that individuals with a dolichocephalic cranial shape have lower tentorial and occipital angles. CONCLUSIONS: The results provide strong evidence proving that the lesser the tentorial and occipital angles, the easier the exposure of the anterior portion of the MTR during the paramedian supracerebellar-transtentorial approach. The tendency of the cranial shape toward dolichocephaly seems to have the same practical value in choosing the approach. It is easier to expose the anterior portion of the MTR in these individuals.

Working memory dysfunction in delusional disorders: an fMRI investigation.

BACKGROUND: Delusional disorder (DD) is a rare and understudied psychiatric disorder. There is limited number of studies concerning cognitive characteristics in DD. Using an established working memory paradigm with variable levels of memory load, we investigated alterations in functional magnetic resonance imaging (fMRI) of brain regions in patients with DD. METHODS: This case control study included 9 patients with DD and 9 healthy control subjects matched for age, sex, and education level. Diagnosis of DD was confirmed using the Structured Clinical Interview for DSM-IV Axis I. The severity of the symptoms was evaluated using the Positive and Negative Syndrome Scale. All patients were asked to perform 0-back and 2-back tasks during fMRI experiments. Functional imaging was performed using the 3.0 T Philips whole-body scanner using an 8-channel head coil. RESULTS: Participants with DD had less neural activation of the left dorsolateral prefrontal cortex in fMRI scans obtained during performance tasks. On the other hand, neural activation of the left and right superior temporal gyrus, left middle and inferior temporal gyrus, right and left posterior cingulate gyrus, right amygdala, left and right fusiform gyrus was more prominent in patients with DD in comparison with the control group. DISCUSSION: Patients with DD had dysfunction in the prefrontal, temporal and limbic regions of the brain in particular, during performance tasks of working memory. Our findings were in line with the findings of the early reports on deficient functioning in temporal or limbic regions of the brain. Further, patients with DD displayed prefrontal dysfunction as seen in patients with schizophrenia.

SMT: a reliability based interactive DTI tractography algorithm.

Tractography refers to the in vivo reconstruction of fiber bundles, e.g., in brain, via the analysis of anisotropic diffusion patterns measured by diffusion weighted magnetic resonance imaging (DWI). The data provides a probabilistic model of local diffusion which was shown to correlate with the underlying fibrous structure under certain assumptions. Deterministic tractography suffers from uncertainties at kissing and crossing fibers, at different levels depending on the diffusion model employed (e.g., DTI, HARDI), yet it is easy to interpret and use in clinic. In this study, a novel generic algorithm, split and merge tractography (SMT), is proposed that provides a real-time, interactive and reliability ranked assessment of potential pathways, communicating the true information content of the data without sacrificing the usability of tractography. Specifically, SMT takes in a precomputed set of tracts and the diffusion data (e.g., DTI, HARDI) as its input, generates a set of short (reliable) tracts via splitting at unreliable points and forms quasi-random clusters of short tracts by means of which the space of short tract clusters, representing complete tracts, is sampled. A histogram of thus formed clusters is built in an efficient way and used for real-time, interactive assessment of pathways. The current implementation uses DTI and fourth-order Runge-Kutta integration based streamline tractography as its input. The method is qualitatively assessed on phantom DTI data and real DTI data. Phantom experiments demonstrated that SMT is capable of highlighting the problematic regions and suggesting pathways that are completely overseen by input streamline tractography. Real data experiment results correlate well with known anatomy and also demonstrate that the reliability ranking can efficiently suppress the erroneous tracts interactively. The method is compared to a recent method that also pursues a similar approach, yet in a global optimization based framework. The comparative study on real DTI data revealed the lower computational load of SMT and a better correlation with known anatomy.

The paramedian supracerebellar-transtentorial approach to the entire length of the mediobasal temporal region: an anatomical and clinical study. Laboratory investigation.

OBJECT: The exploration of lesions in the mediobasal temporal region (MTR) has challenged generations of neurosurgeons to achieve an appropriate approach. To address this challenge, the extensive use of the paramedian supracerebellar-transtentorial (PST) approach to expose the entire length of the MTR, as well as the fusiform gyrus, was investigated. METHODS: The authors studied the microsurgical aspects of the PST approach in 20 cadaver brains and 5 cadaver heads under the operating microscope. They evaluated the features, advantages, difficulties, and limitations of the PST approach and refined the surgical technique. They then used the PST approach in 15 patients with large intrinsic MTR tumors (6 patients), tumor in the posterior fusiform gyrus with mediobasal temporal epilepsy (MTE) (1 patient), cavernous malformations in the posterior MTR including the fusiform gyrus (2 patients), or intractable MTE with hippocampal sclerosis (6 patients) from December 2007 to May 2010. Patients ranged in age from 11 to 63 years (mean 35.2 years), and in 9 patients (60%) the lesion was located on the left side. RESULTS: In all patients with neuroepithelial tumors or cavernous malformations, the lesions were completely and safely resected. In all patients with intractable MTE with hippocampal sclerosis, the anterior two-thirds of the parahippocampal gyrus and hippocampus, as well as the amygdala, were removed selectively through the PST approach. There was no surgical morbidity or mortality in this series. Three patients (20%) with high-grade neuroepithelial tumors underwent postoperative radiotherapy and chemotherapy but needed a second surgery for recurrence during the follow-up period. In all patients with MTE, antiepileptic medication could be decreased to a single drug at lower doses, and no seizure activity has occurred until this point. CONCLUSIONS: The PST approach provides the surgeon precise anatomical orientation when exposing the entire length of the MTR, as well as the fusiform gyrus, for removing any lesion. This is a novel technique especially for removing tumors involving the entire MTR in a single session without damaging neighboring neural or vascular structures. This approach can also be a viable alternative for selective removal of the parahippocampal gyrus, hippocampus, and amygdala in patients with MTE due to hippocampal sclerosis.

Diffusion tensor imaging in carpal tunnel syndrome.

PURPOSE: We aimed to investigate the efficacy of diffusion tensor imaging in the diagnosis of carpal tunnel syndrome and to obtain a quantitative parameter that may contribute to the diagnosis. MATERIALS AND METHODS: The median nerves in 57 wrists of 38 patients diagnosed as carpal tunnel syndrome and 30 wrists of 24 normal subjects were prospectively evaluated with a 3T Philips scanner, using standard 8-channel SENSE head coil. Diffusion tensor imaging was performed using spin echo-echo planar imaging. For anatomical reference, a T1-weighted sequence was acquired. Fractional anisotropy and apparent diffusion coefficient measurements were done focally at the carpal tunnel level and from whole median nerve. RESULTS: In carpal tunnel syndrome patients, both focal carpal tunnel and whole nerve measurements demonstrated statistically significantly lower fractional anisotropy values than normal subjects (P < 0.001). No statistically significant difference was observed in apparent diffusion coefficient measurements. The cut-off value obtained by receiver operator characteristics analysis was 0.554 for focal carpal tunnel fractional anisotropy (sensitivity, 80%; specificity, 80%) and 0.660 for whole nerve fractional anisotropy (sensitivity, 82%; specificity, 80%) measurement. CONCLUSION: Diffusion tensor imaging may contribute to the diagnosis of carpal tunnel syndrome on the basis of fractional anisotropy measurements.

Diffusion tensor imaging in the differentiation of adrenal adenomas and metastases.

PURPOSE: To determine the utility of diffusion tensor imaging for the differentiation of adrenal adenomas and metastases. MATERIALS AND METHODS: Thirty-three patients with a mean age of 59 years were included in this study. Each subject presented with a single adrenal lesion (19 adenomas, 14 metastases). Magnetic resonance imaging (MRI) was performed in the coronal plane using a 3 Tesla MRI and a six-channel phased array SENSE torso coil. T1-weighted in-phase and opposed-phase, T2-weighted turbo spin-echo, and single-shot echo-planar diffusion tensor imaging (DTI) sequences were used for image acquisition. To determine apparent diffusion coefficients (ADC) and fractional anisotropy (FA) values of adrenal lesions, coronal T2-weighted images were used as anatomical references and to localize regions of interest on DTI images. The signal intensity (SI) indices were obtained from in-phase/opposed-phase images by a radiologist blinded to the DTI findings. The DTI parameters were determined by a different radiologist. The SI indices and the differences in FA and ADCs between adenomas and metastases were compared. Analyses of receiver operating characteristics (ROC) were performed to determine the area under the curve (AUC). RESULTS: The SI index of adenomas was found to be significantly higher than the value determined for metastases. Moreover, the median FA value of adrenal adenomas was found to be significantly higher than that of metastases. No statistically significant difference was observed in the ADCs between adenomas and metastases. Furthermore, no significant correlation was found among the SI index and the measured DTI parameters. Based on ROC analyses, the AUC was found to be 0.936 in FA measurements with a 95% confidence interval. The cutoff value obtained from this analysis was 0.40 with maximum sensitivity and specificity values of 74% and 88%, respectively. CONCLUSION: Although no significant difference was observed in the ADCs between adrenal adenomas and metastases, the FA values differed significantly. The FA values may have the potential to differentiate between adrenal adenomas and metastases, which is a possibility that should be validated by further research.

Diffusion tensor imaging of the kidney at 3 Tesla MRI: normative values and repeatability of measurements in healthy volunteers.

PURPOSE: To evaluate the feasibility of renal diffusion tensor imaging and determine the normative fractional anisotropy and apparent diffusion coefficient values at 3 Tesla magnetic resonance imaging (MRI) using parallel imaging and free breathing technique. MATERIALS AND METHODS: A total of 52 young healthy volunteers with no history of renal disease were included in the study. MRI examinations were performed with 3 Tesla MRI equipment, using six-channel phased array SENSE Torso coil. In all subjects, T2-weighted turbo spin echo and diffusion tensor imaging using single shot echo planar imaging sequences were obtained in the coronal plane with free breathing. Field of view, slice thickness, and slice gap values were identical for both sequences for anatomic correlation during analysis of diffusion tensor imaging data. Parallel imaging method was used with a SENSE factor of 2. Diffusion tensor parameters of the cortex and medulla were determined and the intra- and inter-observer measurement variances were calculated. RESULTS: The mean fractional anisotropy of the medulla was significantly higher than that of the cortex, whereas the mean apparent diffusion coefficient of the medulla was lower when compared with that of the cortex. According to the two-sided paired samples Student's t test, the intra- and inter-observer measurements correlated well. CONCLUSION: This study shows the feasibility of renal diffusion tensor imaging and repeatibility of diffusion tensor parameter measurements in 3 Tesla MRI.

Diagnostic utility of DTI in prostate cancer.

PURPOSE: The aim of this study was to compare the diffusion tensor parameters of prostate cancer, prostatitis and normal prostate tissue. MATERIALS AND METHODS: A total of 25 patients with the suspicion of prostate cancer were included in the study. MRI was performed with 3 T system (Intera Achieva, Philips Medical Systems, The Netherlands). T2 TSE and DTI with ss-EPI were obtained in each subject. TRUS-guided prostate biopsy was performed after the MRI examination. Images were analyzed by two radiologists using a special software system. ROI's were drawn according to biopsy zones which are apex, midgland, base and central zone on each sides of the gland. FA and ADC values in areas of cancer, chronic prostatitis and normal prostate tissue were compared using Student's t-test. RESULTS: Histopathological analysis revealed carcinoma in 68, chronic prostatitis in 67 and was reported as normal in 65 zones. The mean FA of cancerous tissue was significantly higher (p<0.01) than the FA of chronic prostatitis and normal gland. The mean ADC of cancerous tissue was found to be significantly lower (p<0.01), compared with non-cancerous tissue. CONCLUSION: Decreased ADC and increased FA are compatible with the hypercellular nature of prostate tumors. These differences may increase the accuracy of MRI in the detection of carcinoma and to differentiate between cancer and prostatitis.