Atherosclerotic Carotid Plaques: Multimodality Imaging with Contrast-enhanced Ultrasound, Computed Tomography, and Magnetic Resonance Imaging.

INTRODUCTION: The imaging of carotid plaques has undergone a paradigm shift increasing importance being given to plaque characterization. Patients with "vulnerable" plaques are more prone to develop future neurovascular events. PURPOSE: The purpose of this study is to analyze the role of multimodality imaging techniques in the assessment of carotid atherosclerotic plaques. MATERIALS AND METHODS: Twenty-six patients were prospectively enrolled in the study. Patients underwent multidetector computed tomography (CT) angiography, ultrasound, contrast-enhanced ultrasound, and high-resolution magnetic resonance imaging (MRI) of the carotid arteries with special emphasis on the carotid bifurcation. RESULTS: The mean age of patients was 65.41 years. Twenty-one were males. Plaque neovascularization was seen in 10 of the 18 plaques studied (55.56%). Based on the predominant components of the plaque, plaques were characterized as lipid (3), lipid with recent hemorrhage (1), fibrous (7), fibrofatty (4), fibrofatty with some hemorrhagic components (3), and recent hemorrhage (2). CONCLUSIONS: Together, contrast-enhanced ultrasound, CT, and MRI provide complete information about the plaque characteristics.

Plasmacytoma of the clivus.

We report a case of solitary plasmacytoma of the clivus in a 55 year old male.

Susceptibility weighted imaging - a problem-solving tool in differentiation of cerebellopontine angle schwannomas and meningiomas.

Background and purpose Vestibular schwannomas and meningiomas of the cerebellopontine angle can be differentiated by the presence of foci of blooming on susceptibility weighted imaging. Materials and methods In this retrospective study, magnetic resonance imaging with susceptibility weighted imaging sequence in addition to other routine sequences was done in 73 patients. All the cases were studied for the presence of foci of blooming within the tumor on susceptibility weighted imaging. Histopathological examination confirmed the diagnosis in all cases. Results There were 59 patients in the vestibular schwannoma group and 14 in the meningioma group. Susceptibility weighted imaging showed presence of blooming (due to microhemorrhages) in all the cases of cerebellopontine angle schwannomas. In the meningioma group, 13 cases showed no blooming within the lesion; one case showed blooming which was confirmed to be due to calcification on computed tomography study. For the detection of foci of blooming and predicting histopathologic diagnosis of schwannoma pre-operatively, susceptibility weighted imaging showed a sensitivity of 100%, specificity of 92%, positive predictive value of 98.3%, and negative predictive value of 100%. The Fisher exact test showed a statistically significant difference in the differentiation of vestibular schwannoma from meningioma on the basis of detection of blooming on susceptibility weighted imaging ( p < 0.0001). Conclusion Susceptibility weighted imaging is a problem-solving tool in making accurate pre-operative differentiation of vestibular schwannoma from meningioma.

Resting state fMRI: A review on methods in resting state connectivity analysis and resting state networks.

The inquisitiveness about what happens in the brain has been there since the beginning of humankind. Functional magnetic resonance imaging is a prominent tool which helps in the non-invasive examination, localisation as well as lateralisation of brain functions such as language, memory, etc. In recent years, there is an apparent shift in the focus of neuroscience research to studies dealing with a brain at 'resting state'. Here the spotlight is on the intrinsic activity within the brain, in the absence of any sensory or cognitive stimulus. The analyses of functional brain connectivity in the state of rest have revealed different resting state networks, which depict specific functions and varied spatial topology. However, different statistical methods have been introduced to study resting state functional magnetic resonance imaging connectivity, yet producing consistent results. In this article, we introduce the concept of resting state functional magnetic resonance imaging in detail, then discuss three most widely used methods for analysis, describe a few of the resting state networks featuring the brain regions, associated cognitive functions and clinical applications of resting state functional magnetic resonance imaging. This review aims to highlight the utility and importance of studying resting state functional magnetic resonance imaging connectivity, underlining its complementary nature to the task-based functional magnetic resonance imaging.

Combining Diffusion Tensor Metrics and DSC Perfusion Imaging: Can It Improve the Diagnostic Accuracy in Differentiating Tumefactive Demyelination from High-Grade Glioma?

BACKGROUND AND PURPOSE: Tumefactive demyelinating lesions with atypical features can mimic high-grade gliomas on conventional imaging sequences. The aim of this study was to assess the role of conventional imaging, DTI metrics (p:q tensor decomposition), and DSC perfusion in differentiating tumefactive demyelinating lesions and high-grade gliomas. MATERIALS AND METHODS: Fourteen patients with tumefactive demyelinating lesions and 21 patients with high-grade gliomas underwent brain MR imaging with conventional, DTI, and DSC perfusion imaging. Imaging sequences were assessed for differentiation of the lesions. DTI metrics in the enhancing areas and perilesional hyperintensity were obtained by ROI analysis, and the relative CBV values in enhancing areas were calculated on DSC perfusion imaging. RESULTS: Conventional imaging sequences had a sensitivity of 80.9% and specificity of 57.1% in differentiating high-grade gliomas (P = .049) from tumefactive demyelinating lesions. DTI metrics (p:q tensor decomposition) and DSC perfusion demonstrated a statistically significant difference in the mean values of ADC, the isotropic component of the diffusion tensor, the anisotropic component of the diffusion tensor, the total magnitude of the diffusion tensor, and rCBV among enhancing portions in tumefactive demyelinating lesions and high-grade gliomas (P ≤ .02), with the highest specificity for ADC, the anisotropic component of the diffusion tensor, and relative CBV (92.9%). Mean fractional anisotropy values showed no significant statistical difference between tumefactive demyelinating lesions and high-grade gliomas. The combination of DTI and DSC parameters improved the diagnostic accuracy (area under the curve = 0.901). Addition of a heterogeneous enhancement pattern to DTI and DSC parameters improved it further (area under the curve = 0.966). The sensitivity increased from 71.4% to 85.7% after the addition of the enhancement pattern. CONCLUSIONS: DTI and DSC perfusion add profoundly to conventional imaging in differentiating tumefactive demyelinating lesions and high-grade gliomas. The combination of DTI metrics and DSC perfusion markedly improved diagnostic accuracy.

Quantification of diffusion and anisotropy in intracranial epidermoids using diffusion tensor metrics and p: q tensor decomposition.

PURPOSE: To quantitatively evaluate the diffusion tensor metrics p, q, L and fractional anisotropy in intracranial epidermoids in comparison with normal white matter in the splenium of the corpus callosum. METHODS: This retrospective study included 20 consecutive patients referred to our institute. All patients had a magnetic resonance imaging (MRI) study on a 1.5-Tesla MR system. A spin-echo echo-planar DTI sequence with diffusion gradients along 30 non-collinear directions was performed. The eigen values (λ1, λ2, λ3) were computed for each voxel and, using p: q tensor decomposition, the DTI metrics p, q and L-values and fractional anositropy (FA) were calculated. The region of interest (ROI) (6 pixels each) was placed within the lesion in all the cases and in the splenium of the corpus callosum. RESULTS: The mean FA in the lesion and splenium were 0.50 and 0.88 respectively, with a statistically significant difference between them (P<0.01). On p: q tensor decomposition, the mean p-value in the epidermoid was 1.55±0.24 and 1.35±0.20 in the splenium; the mean q-values in the epidermoid was 0.67±0.13 and 1.27±0.17 in the splenium; the differences were statistically significant (P=0.01 and <0.01 respectively). The significant difference between p- and q-values in epidermoids compared with the splenium of callosum was probably due to structural and orientation differences in the keratin flakes in epidermoids and white matter bundles in the callosum. However, no significant statistical difference in L-values was noted (P=0.44). CONCLUSION: DTI metrics p and q have the potential to quantify the diffusion and anisotropy in various tissues thereby gaining information about their internal architecture. The results also suggest that significant differences of DTI metrics p and q between epidermoid and the splenium of the corpus callosum are due to the difference in structural organization within them.

Surgical Closure of Aortopulmonary Window in a Topsy-Turvy Heart: A Surgical Challenge.

Topsy-turvy heart is a rare congenital cardiac anomaly characterized by a 90° rotation of the heart along its long axis. The great vessels originate posteroinferiorly, and the arch vessels are elongated and join the aorta well below the carina. It is usually associated with aortic arch and tracheobronchial anomalies. Cardiopulmonary bypass is challenging in these patients because of the abnormal position of the great vessels. We describe the surgical management of aortopulmonary window in a topsy-turvy heart in a 14-day-old girl.

Imaging of skull base pathologies: Role of advanced magnetic resonance imaging techniques.

Imaging plays a vital role in evaluation of skull base pathologies as this region is not directly accessible for clinical evaluation. Computerized tomography (CT) and magnetic resonance imaging (MRI) have played complementary roles in the diagnosis of the various neoplastic and non-neoplastic lesions of the skull base. However, CT and conventional MRI may at times be insufficient to correctly pinpoint the accurate diagnosis. Advanced MRI techniques, though difficult to apply in the skull base region, in conjunction with CT and conventional MRI can however help in improving the diagnostic accuracy. This article aims to highlight the importance of advanced MRI techniques like diffusion-weighted imaging, susceptibility-weighted imaging, perfusion-weighted imaging, and MR spectroscopy in differentiation of various lesions involving the skull base.

Varying clinical and imaging outcomes in patients with spontaneous thrombosis of vein of Galen malformation--a report of two cases.

BACKGROUND: Vein of Galen malformations are rare congenital intracranial vascular malformations. The pathophysiological consequences usually manifest as high-output cardiac failure and neurological symptoms secondary to cerebral venous congestion and abnormal CSF flow. Management of these patients is complex. Indications and time to intervene are decided depending upon the age of child, clinical presentation, and multisystemic neonatal scores. Many of these children presenting early and who are not in cardiac failure are expectantly followed up. Spontaneous thrombosis of the vein of Galen malformation is a rare occurrence in these as such rare vascular malformations. METHODS: This review reports two cases of spontaneous thrombosis of the vein of Galen malformations with varying clinical as well as imaging outcomes. Possible pathophysiologic mechanisms are discussed with review of literature. RESULTS: This report highlights the importance of vigilant clinical and imaging follow-up even after spontaneous thrombosis in the vein of Galen malformations.

Intracranial ewings sarcoma/peripheral primitive neuroectodermal tumor.

Central nervous system primitive neuroectodermal tumours (CNS PNET) are aggressive embryonal tumours composed of undifferentiated or poorly differentiated neuroepithelial cells seen in the pediatric age group. This is rare and only a handful of cases of ES/pPNET in CNS are reported. We report such a case in a 3 year old child. Reporting of more such cases is needed to better define these rare tumours of the dura.

Radiologic technologists' radiation safety knowledge in India: a multicenter survey.

PURPOSE: To assess radiation safety knowledge of radiologic technologists in India, assess the effect of current technologist training programs on radiation safety knowledge, and identify knowledge gaps. METHOD: A total of 174 radiologic technologists from 31 centers completed a survey containing theoretical and practical questions assessing radiation knowledge. Scores were analyzed based on years of experience and prior radiation training. Group mean scores were analyzed with students' t test and one-way analysis of variance. The Fisher exact test was used to analyze the difference in performance between the trained and untrained groups. RESULTS: Thirty-two percent of the 174 respondents had received formal radiation safety training. The mean score on the questionnaire was 6.98 out of 14 total points; 66.67% of respondents scored 7 (50%) or above. The mean theoretical and practical scores (out of 7 total points each) were 4.48 and 2.49, respectively. There was no statistically significant difference between theoretical and practical scores based on years of experience. The untrained group had higher mean total and practical scores but lower mean theory scores, with a statistically significant difference for total and practical scores between the trained and untrained groups. DISCUSSION: Although many radiologic procedures are performed in India, most technologists reported not being trained in radiation safety, even though most realized that training is necessary. The lack of improvement in scores with years of experience indicates the need for continuing professional education focusing on the practical aspects of safety. CONCLUSION: Professional continuing education programs for radiologic technologists should be integrated into every radiology department and monitored with quality and performance audits.

Diffusion tensor imaging and tractography of the human language pathways: moving into the clinical realm.

The functional correlates of anatomical derangements are of interest to the neurological clinician. Diffusion tensor tractography (DTT) is a relatively new tool in the arsenal of functional neuroimaging, by which to assess white matter tracts in the brain. While much import has been given to tracking corticospinal tracts in neurological disease, studying language pathway interconnections using DTT has largely remained in the research realm. Hardware and software advances have allowed this tool to ease into clinical practice, with several radiologists, neurologists, and neurosurgeons now familiar with its applications. DTT images, although visually appealing, are founded in mathematical equations and assumptions, and require a more than basic understanding of principles and limitations before they can be integrated into routine clinical practice. Cognitive pathways like that of language, that are normally hard to assess and especially more so when pathologically affected, have been at the receiving end of several opposing and often controversial hypotheses, and the past decade has seen the clarification, validation or rejection of several of these by the in vivo charting of functional connectivity using DTT. The focus of this review is to illustrate DTT of the language pathways with emphasis on practical considerations, clinical applications, and limitations.

An unusual cause for unruptured sinus of valsalva aneurysm.

Sinus of valsalva aneurysm is considered to be one of the rarest complications of inflammatory aortitis. Herewith, we are reporting a young male patient who presented to us with severe aortic regurgitation. On evaluation, he was found to have unruptured sinus of valsalva aneurysm. CT angiography and magnetic resonance imaging have shown value in the diagnosis of sinus of valsalva aneurysm.