Eric H. Hanson

Traumatic Brain Injury: A Review and High-Field MRI Findings in 100 Unarmed Combatants Using a Literature-Based Checklist Approach

This study reviewed the literature for the extent of neuroimaging findings in boxers, indicative of traumatic brain injury (TBI) as identified in magnetic resonance imaging (MRI). The study then utilized a systematic checklist approach to assess 100 unselected consecutive 1.5- and 3.0-Tesla MRI examinations of professional unarmed combatants to determine the extent of identifiable TBI findings. The percentage of positive findings and the localization of lesions were quantified using the checklist that included the MRI findings previously reported in the medical literature. Seventy-six percent of the unarmed combatants had at least one finding that may be associated with TBI: 59% hippocampal atrophy, 43% cavum septum pellucidum, 32% dilated perivascular spaces, 29% diffuse axonal injury, 24% cerebral atrophy, 19% increased lateral ventricular size, 14% pituitary gland atrophy, 5% arachnoid cysts, and 2% had contusions. Statistical relationships were found between number of bouts and lateral ventricular size (tau-b = 0.149, p = 0.0489), with years of fighting correlating with the presence of dilated perivascular spaces (tau-b = 0.167, p = 0.0388) and diffuse axonal injury (tau-b = 0.287, p = 0.0013) findings. The improved resolution and increased signal-to-noise ratio on 1.5- and 3.0-Tesla high-field MRI systems defines the range of pathological variations that may occur in professional unarmed combatants. Additionally, the use of a systematic checklist approach insures evaluation for all possible TBI-related abnormalities. This knowledge can be used to anticipate the regions of potential brain pathology for radiologists and emergency medicine physicians, and provides important information for evaluating unarmed combatants relative to their safety and long-term neurocognitive outcome.

Whole-brain dynamic CT angiography and perfusion imaging

The availability of whole brain computed tomography (CT) perfusion has expanded the opportunities for analysing the haemodynamic parameters associated with varied neurological conditions. Examples demonstrating the clinical utility of whole-brain CT perfusion imaging in selected acute and chronic ischaemic arterial neurovascular conditions are presented. Whole-brain CT perfusion enables the detection and focused haemodynamic analyses of acute and chronic arterial conditions in the central nervous system without the limitation of partial anatomical coverage of the brain.

Sagittal whole-spine magnetic resonance imaging in 750 consecutive outpatients: accurate determination of the number of lumbar vertebral bodies.

OBJECT When the number of lumbar and sacral vertebrae is being assessed, variations from typical lumbosacral anatomy may confuse the practitioner, potentially leading to significant clinical errors. In this study, the authors describe the statistical variation in lumbar spine anatomy in an outpatient imaging setting, evaluate the potential implications for clinical practice based on the variation in the number of lumbar-type vertebrae identified, and recommend a method for rapidly determining the number of lumbar spine vertebral bodies (VBs) in outpatients referred for lumbar spine MR imaging. METHODS A total of 762 patients (male and female) who presented with low back-related medical conditions underwent whole-spine MR imaging in an outpatient setting. RESULTS The high-speed whole-spine evaluation was successful for determining the number of lumbar-type VBs in 750 (98%) of 762 consecutive patients. The sagittal whole-spine 3-T MR imaging system images obtained between the beginning of January 2005 and the end of February 2007 were reviewed. The VBs were counted successively from the level of C-2 inferiorly to the intervertebral disc below the most inferior lumbar-type VB. Numbers of disc herniations were also evaluated in the context of the number of VBs. CONCLUSIONS One in 5 of these outpatients did not have 5 lumbar-type vertebrae: 14.5% had 6; 5.3% had 4; and 1 (0.13%) had the rare finding of 3 lumbar-type vertebrae. Two-thirds of the individuals with 6 lumbar-type vertebrae were male and two-thirds of the individuals with 4 lumbar-type vertebrae were female. Sagittal whole-spine MR imaging can be performed rapidly and efficiently in the majority of patients (98%), and provides improved accuracy for the determination of the number of lumbar-type VBs. A supplementary coronal MR, Ferguson view radiograph or intraoperative fluoroscopic determination for the presence of lumbosacral transitional vertebrae may add additional information when indicated for clinical treatment or surgical planning.

Appearance and impact of post-operative intracranial clips and coils on whole-brain CT angiography and perfusion

BACKGROUND To evaluate the effect of vascular clips and endovascular coils placed for intracranial aneurysms and arteriovenous malformations on whole-brain computed tomography (CT) angiography and perfusion. METHODS A 320-detector row dynamic volume CT system imaged 11 patients following surgical placement of vascular clips or endovascular coils. The extent of clip and coil subtraction by automated software was evaluated using CT digital subtraction angiography and CT perfusion. Impact on CT perfusion values by retained intracranial devices was compared to age- and gender-matched controls. RESULTS Clip and coil subtraction on CT angiography was graded as good in 8 and moderate in 3 cases. A residual neck and additional aneurysm were noted in 1 of 11 patients. Post-procedural axial slice level CT perfusion values decreased in reliability with increasing proximity to the metallic devices secondary to beam hardening. However, the intracranial devices did not affect axial slice level CTP values of cerebral blood volume, cerebral blood flow and mean transit time outside of the level of the device. Time to peak values was globally decreased outside of the immediate vascular intervention region. CONCLUSIONS Advances in CT technology have provided clinically useful subtraction of intracranial clips and coils. While CT perfusion values were altered in device subtraction areas and within beam hardening artifact areas; they can provide valuable postoperative information on whole-brain hemodynamics. In selected cases, the combination of CT angiography and whole-brain CT perfusion can offer an alternative to conventional angiography that is a more invasive option.

Assessment of the Tracer Delay Effect in Whole-Brain Computed Tomography Perfusion: Results in Patients Without Known Neuroanatomic Abnormalities.

Objective Whole-brain computed tomography perfusion (CTP) data sets generated by tracer delay–insensitive singular value decomposition plus (SVD+) and standard singular value decomposition (sSVD) deconvolution algorithms were evaluated to quantify relatedness and discrepancies in CTP results. Methods Twenty females with symmetrical hemispheric CTP maps indicative of brain tissue without apparent abnormalities were studied. Tissue-specific CTP values were analyzed. Results Standard SVD values were higher than SVD+ for cerebral blood flow. Other CTP values had minimal differences across brain regions. All simple linear regression models were statistically significant (P < 0.05) except for cerebral blood flow in white matter (P = 0.06). Cerebral blood volume had a good model fit, and mean transit time, a poor fit. Conclusions Corresponding fitted CTP values for sSVD and SVD+ based on regression equations for brain-tissue types are presented. Additional research is required to compare SVD+ and sSVD in disease states when significant hemodynamic brain alterations are present.

An amalgamated risk estimation model (REM) and assay integration into future REMs

The clinical reality of the post-genomic era is that we now face even more complex disease processes when provided with genomic information, including multifactorial genetic and genomic influences, and epigenetic and environmental factors. A useful example of the promise and perils of genomic technologies and information is breast cancer. By the mid-1990s, two genes (BRCA1 and BRCA2) had been identified, accounting for approximately 5% of affected individuals. Since then, surprisingly few genetic breast cancer risk factors have been identified to account for the remaining 95%. To efficiently and cost-effectively identify individuals at high risk, a combination of information components is required: a patient-reported personal and family medical history; clinical data (for example, a physical exam, pathology results, laboratory test results and imaging); and genetic/genomic results. Gaining comprehensive data from all of these areas provides the best risk assessment and management options for patients. Furthermore, high quality patient and clinical information is essential for the accurate and reliable interpretation of genomic results. We have clinically implemented a platform that integrates all three informational components with multiple risk estimation models (REMs) to produce an effective automated method for risk-stratifying patients. Although this platform can be and has been applied to a wide range of genetic conditions, this presentation will use breast cancer to illustrate the approach. This system consists of three primary components: a secure web-based questionnaire used by patients to enter personal and family medical history; a tablet-based system for collecting clinical and genomic information; and an analysis engine that seamlessly integrates REMs that have been developed to calculate either a woman’s risk of developing breast cancer during her lifetime (Claus, Gail II, BRCAPRO, BOADICEA and IBIS) or the probability of detecting a hereditary breast cancer gene mutation (Myriad, Penn II, BRCAPRO, BOADICEA and IBIS).This use of multiple or amalgamated REM (aREM) results offers one of the most comprehensive breast cancer risk assessments available for predicting the lifetime risk of developing breast cancer or the presence of BRCA mutations. Additional uses for aREMs include rapid analyses of existing breast cancer datasets, external validation of new REMs, and prospective outcome comparisons based on initial aREM results. Numerous biomarkers for breast cancer, in addition to BRCA1 and BRCA2 mutations, have been reported, but few molecular markers or assays have been adopted for clinical use. The addition of novel REMs that integrate a new molecular assay or classifiers can facilitate the identification of an enriched population for screening (for example, lowering the number needed to screen) or for diagnostic, prognostic or therapeutic purposes. REMs are rapidly integrating multiple genetic influences, whole genome sequencing data and epigenetic modifications, so structured comparisons of the performance of existing and emerging predictive REMs are required for safe and effective clinical application.

Magnetic resonance venography and genetics of a female patient with pelvic venous thrombosis

A femoral vein thrombosis, originally diagnosed with conventional ultrasound, was fully elucidated and monitored utilizing serial high-resolution magnetic resonance venography in a 19-year-old female with a family history of venous thromboembolism. Genetic testing revealed she was heterozygous for a F5 gene mutation, an abnormality that predisposes carriers to factor V Leiden thrombophilia. An additional risk factor included use of oral contraceptive pills. Subsequent testing of her family uncovered other carriers of the mutation, allowing for the implementation of preventive measures for the entire family. Although magnetic resonance venography has not yet proven to be a cost-effective method for monitoring clot resolution, the case presented here encourages further research on the clinical utility and cost-benefit of utilizing this technology for monitoring venous thrombosis and for clinical management purposes.