Gaurav Saigal

Whole-Brain Proton MR Spectroscopic Imaging of Mild-to-Moderate Traumatic Brain Injury and Correlation with Neuropsychological Deficits

Changes in the distribution of the magnetic resonance (MR)-observable brain metabolites N-acetyl aspartate (NAA), total choline (Cho), and total creatine (Cre), following mild-to-moderate closed-head traumatic brain injury (mTBI) were evaluated using volumetric proton MR spectroscopic imaging (MRSI). Studies were carried out during the subacute time period following injury, and associations of metabolite indices with neuropsychological test (NPT) results were evaluated. Twenty-nine subjects with mTBI and Glasgow Coma Scale (GCS) scores of 10-15 were included. Differences in individual metabolite and metabolite ratio distributions relative to those of age-matched control subjects were evaluated, as well as analyses by hemispheric lobes and tissue types. Primary findings included a widespread decrease of NAA and NAA/Cre, and increases of Cho and Cho/NAA, within all lobes of the TBI subject group, and with the largest differences seen in white matter. Examination of the association between all of the metabolite measures and the NPT scores found the strongest negative correlations to occur in the frontal lobe and for Cho/NAA. No significant correlations were found between any of the MRSI or NPT measures and the GCS. These results demonstrate that significant and widespread alterations of brain metabolites occur as a result of mild-to-moderate TBI, and that these measures correlate with measures of cognitive performance.

Conventional and Advanced MRI Features of Pediatric Intracranial Tumors: Supratentorial Tumors

OBJECTIVE. Our objective is to review the imaging characteristics and applications of conventional and advanced neuroimaging techniques of supratentorial intracranial masses in the pediatric population. Specifically, we review astrocytomas, oligodendrogliomas, primary neuroectodermal tumors, dysembryoplastic neuroepithelial tumors, gangliogliomas, arachnoid cysts, and choroid plexus and pineal region masses. CONCLUSION. Advanced imaging methods, such as MR spectroscopy, perfusion MRI, functional MRI, diffusion-tensor imaging, and tractography, help develop a more accurate differential diagnosis and aid in planning tumor treatment.

1H MRS of basal ganglia and thalamus in amyotrophic lateral sclerosis.

Previous studies have evaluated motor and extramotor cerebral cortical regions in patients with amyotrophic lateral sclerosis (ALS) using 1H MRS, but none have evaluated the thalamus or basal ganglia. The objective of this exploratory study was to evaluate the subclinical involvement of the basal ganglia and thalamus in patients with ALS using 1H MRS. Fourteen patients (52 ± 7 years) with sporadic definite ALS and 17 age‐matched controls were studied using volumetric MRSI on a 3‐T scanner. The concentration of the metabolites N‐acetylaspartate (NAA), choline (Cho) and their ratio (NAA/Cho) were obtained bilaterally from the basal ganglia (lentiform nucleus, caudate) and thalamus. The maximum rates of finger and foot tap and lip and tongue movements were obtained to assess extrapyramidal and pyramidal tract function. In patients with ALS, relative to controls, the NAA concentration was significantly lower (p < 0.02) in the basal ganglia and thalamus, and the Cho concentration was higher (p < 0.01) in these structures, except in the caudate (p = 0.04). Correspondingly, the NAA/Cho ratio was significantly lower (p < 0.01) in these structures, except in the caudate (p = 0.03), in patients than in controls. There were mild to strong correlations (r = 0.4–0.7) between the metabolites of the basal ganglia and finger tap, foot tap and lip and tongue movement rates. In conclusion, decreased NAA in the basal ganglia and thalamus and increased Cho and decreased NAA/Cho in the lentiform nucleus and thalamus are indicative of neuronal loss or dysfunction and alterations in choline‐containing membranes in these structures. Copyright

Conventional and Advanced MRI Features of Pediatric Intracranial Tumors: Posterior Fossa and Suprasellar Tumors

OBJECTIVE In this article, we review the most common posterior fossa and suprasellar intracranial neoplasms in the pediatric population. We briefly discuss basic MRI concepts used in the initial evaluation of a pediatric brain tumor and then discuss sophisticated MRI techniques that give insight into the physiology and chemical makeup of these tumors to help the radiologist make a more specific diagnosis. CONCLUSION Diagnosis and treatment of pediatric CNS tumors necessitate a multi-disciplinary approach and require expertise and diligence of all parties involved. Imaging is an essential component has evolved greatly over the past decade. We are becoming better at making a preoperative diagnosis of that tumor type, detecting recurrence, and guiding surgical management to avoid injury to vital brain structures.

Comprehensive Evaluation of Corticospinal Tract Metabolites in Amyotrophic Lateral Sclerosis Using Whole-Brain 1H MR Spectroscopy

Changes in the distribution of the proton magnetic resonance spectroscopy (MRS) observed metabolites N-acetyl aspartate (NAA), total-choline (Cho), and total-creatine (Cre) in the entire intracranial corticospinal tract (CST) including the primary motor cortex were evaluated in patients with amyotrophic lateral sclerosis (ALS). The study included 38 sporadic definite-ALS subjects and 70 age-matched control subjects. All received whole-brain MR imaging and spectroscopic imaging scans at 3T and clinical neurological assessments including percentage maximum forced vital capacity (FVC) and upper motor neuron (UMN) function. Differences in each individual metabolite and its ratio distributions were evaluated in the entire intracranial CST and in five segments along the length of the CST (at the levels of precentral gyrus (PCG), centrum semiovale (CS), corona radiata (CR), posterior limb of internal capsule (PLIC) and cerebral peduncle (CP)). Major findings included significantly decreased NAA and increased Cho and Cho/NAA in the entire intracranial CST, with the largest differences for Cho/NAA in all the groups. Significant correlations between Cho/NAA in the entire intracranial CST and the right finger tap rate were noted. Of the ten bilateral CST segments, significantly decreased NAA in 4 segments, increased Cho in 5 segments and increased Cho/NAA in all the segments were found. Significant left versus right CST asymmetries were found only in ALS for Cho/NAA in the CS. Among the significant correlations found between Cho/NAA and the clinical assessments included the left-PCG versus FVC and right finger tap rate, left -CR versus FVC and right finger tap rate, and left PLIC versus FVC and right foot tap rate. These results demonstrate that a significant and bilaterally asymmetric alteration of metabolites occurs along the length of the entire intracranial CST in ALS, and the MRS metrics in the segments correlate with measures of disease severity and UMN function.

ACR Appropriateness Criteria Head Trauma—Child

Head trauma is a frequent indication for cranial imaging in children. CT is considered the first line of study for suspected intracranial injury because of its wide availability and rapid detection of acute hemorrhage. However, the majority of childhood head injuries occur without neurologic complications, and particular consideration should be given to the greater risks of ionizing radiation in young patients in the decision to use CT for those with mild head trauma. MRI can detect traumatic complications without radiation, but often requires sedation in children, owing to the examination length and motion sensitivity, which limits rapid assessment and exposes the patient to potential anesthesia risks. MRI may be helpful in patients with suspected nonaccidental trauma, with which axonal shear injury and ischemia are more common and documentation is critical, as well as in those whose clinical status is discordant with CT findings. Advanced techniques, such as diffusion tensor imaging, may identify changes occult by standard imaging, but data are currently insufficient to support routine clinical use. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Distributions of Magnetic Resonance Diffusion and Spectroscopy Measures with Traumatic Brain Injury

Magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) studies have demonstrated that measures of altered metabolism and axonal injury can be detected following traumatic brain injury. The aim of this study was to characterize and compare the distributions of altered image parameters obtained by these methods in subjects with a range of injury severity and to examine their relative sensitivity for diagnostic imaging in this group of subjects. DTI and volumetric magnetic resonance spectroscopic imaging data were acquired in 40 subjects that had experienced a closed-head traumatic brain injury, with a median of 36 d post-injury. Voxel-based analyses were performed to examine differences of group mean values relative to normal controls, and to map significant alterations of image parameters in individual subjects. The between-group analysis revealed widespread alteration of tissue metabolites that was most strongly characterized by increased choline throughout the cerebrum and cerebellum, reaching as much as 40% increase from control values for the group with the worse cognitive assessment score. In contrast, the between-group comparison of DTI measures revealed only minor differences; however, the Z-score image analysis of individual subject DTI parameters revealed regions of altered values relative to controls throughout the major white matter tracts, but with considerable heterogeneity between subjects and with a smaller extent than the findings for altered metabolite measures. The findings of this study illustrate the complimentary nature of these neuroimaging methods.

Extended Progression-Free Survival in Two Patients With Alveolar Soft Part Sarcoma Exposed to Tivantinib

Introduction Alveolar soft part sarcoma (ASPS) is a rare malignancy that tends to strike young adults and adolescents. It has an unusual clinical behavior; it is somewhat indolent, with slow progression, and yet is incurable once metastasized. Patients with ASPS often present with extensive metastatic disease, frequently involving the lungs and sometimes the brain. On the basis of functional data linking the characteristic translocation found in ASPS, ASPL-TFE3, to upregulation of expression of the MET receptor tyrosine kinase, we proposed to conduct a clinical trial of tivantinib, an orally available, selective inhibitor of MET, for patients with ASPS and other cancers with expression of MET. This was a phase II study with response as the primary outcome (A Phase II Study of ARQ 197 in Patients With Microphthalmia Transcription Factor Associated Tumors). Herein we report two young patients from this trial who have continued on therapy for more than 3 years each, with stable disease and minimal adverse effects, despite metastases at study entry. During the time of the trial, the study dose of tivantinib was increased from 120 mg twice a day to 360 mg twice a day, on the basis of ongoing parallel pharmacokinetic studies. The study was Institutional Review Board approved at each institution where these patients were treated. The consent process for these minors included obtaining the appropriate assent from the patient and informed consent from the parents.

Gomez-Lopez-Hernandez syndrome.

We describe a case of Gomez-Lopez-Hernandez syndrome in an 18-month-old boy. Imaging findings included rhombencephalosynapsis with a single dentate nucleus. In addition, MR angiography revealed an azygous anterior cerebral artery. The clinical presentation, MRI findings and pathogenesis are discussed.

Transplacental passage of non-ionic contrast agents resulting in fetal bowel opacification: a mimic of pneumoperitoneum in the newborn

Although animal studies suggest that non-ionic radiological contrast agents do not cross the placenta, case reports have documented transplacental passage of the non-ionic monomers iohexol and iopromide in humans. We report a case of presumed transplacental passage of the non-ionic monomer ioversol resulting in fetal bowel opacification and mimicking pneumoperitoneum.