The purpose of this study was to measure the organ doses and estimate the effective dose for the standard brain perfusion CT protocol and erroneous protocols.
An anthropomorphic phantom with metal ...oxide semiconductor field effect transistor (MOSFET) detectors was scanned on a 64-MDCT scanner. Protocol 1 used a standard brain perfusion protocol with 80 kVp and fixed tube current of 200 mA. Protocol 2 used 120 kVp and fixed tube current of 200 mA. Protocol 3 used 120 kVp with automatic tube current modulation (noise index, 2.4; minimum, 100 mA; maximum, 520 mA).
Compared with protocol 1, the effective dose was 2.8 times higher with protocol 2 and 7.8 times higher with protocol 3. For all protocols, the peak dose was highest in the skin, followed by the brain and calvarial marrow. Compared with protocol 1, the peak skin dose was 2.6 times higher with protocol 2 and 6.7 times higher with protocol 3. The peak skin dose for protocol 3 exceeded 3 Gy. The ocular lens received significant scatter radiation: 177 mGy for protocol 2 and 435 mGy for protocol 3, which were 4.6 and 11.3 times the dose for protocol 1, respectively.
Compared with the standard protocol, erroneous protocols of increasing the tube potential from 80 kVp to 120 kVp will lead to a three- to fivefold increase in organ doses, and concurrent use of high peak kilovoltage with incorrectly programmed tube current modulation can increase dose to organs by 7- to 11-fold. Tube current modulation with a low noise index can lead to doses to the skin and ocular lens that are close to thresholds for tissue reactions.
Background: Folate metabolism pathway genes have been examined for association with neural tube defects (NTDs) because folic acid supplementation reduces the risk of this debilitating birth defect. ...Most studies addressed these genes individually, often with different populations providing conflicting results. Objectives: Our study evaluates several folate pathway genes for association with human NTDs, incorporating an environmental cofactor: maternal folate supplementation. Methods: In 304 Caucasian American NTD families with myelomeningocele or anencephaly, we examined 28 polymorphisms in 11 genes: folate receptor 1, folate receptor 2, solute carrier family 19 member 1, transcobalamin II, methylenetetrahydrofolate dehydrogenase 1, serine hydroxymethyltransferase 1, 5,10-methylenetetrahydrofolate reductase (MTHFR), 5-methyltetrahydrofolate-homocysteine methyltransferase, 5-methyltetrahydrofolate-homocysteine methyltransferase reductase, betaine-homocysteine methyltransferase (BHMT), and cystathionine-beta-synthase. Results: Only single nucleotide polymorphisms (SNPs) in BHMT were significantly associated in the overall data set; this significance was strongest when mothers took folate-containing nutritional supplements before conception. The BHMT SNP rs3733890 was more significant when the data were stratified by preferential transmission of the MTHFR rs1801133 thermolabile T allele from parent to offspring. Other SNPs in folate pathway genes were marginally significant in some analyses when stratified by maternal supplementation, MTHFR, or BHMT allele transmission. Conclusions: BHMT rs3733890 is significantly associated in our data set, whereas MTHFR rs 1801133 is not a major risk factor. Further investigation of folate and methionine cycle genes will require extensive SNP genotyping and/or resequencing to identify novel variants, inclusion of environmental factors, and investigation of gene-gene interactions in large data sets.
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BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, OILJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
Chiari Type I Malformation (CMI) is characterized by herniation of the cerebellar tonsils through the foramen magnum at the base of the skull, resulting in significant neurologic morbidity. As CMI ...patients display a high degree of clinical variability and multiple mechanisms have been proposed for tonsillar herniation, it is hypothesized that this heterogeneous disorder is due to multiple genetic and environmental factors. The purpose of the present study was to gain a better understanding of what factors contribute to this heterogeneity by using an unsupervised statistical approach to define disease subtypes within a case-only pediatric population.
A collection of forty-four pediatric CMI patients were ascertained to identify disease subtypes using whole genome expression profiles generated from patient blood and dura mater tissue samples, and radiological data consisting of posterior fossa (PF) morphometrics. Sparse k-means clustering and an extension to accommodate multiple data sources were used to cluster patients into more homogeneous groups using biological and radiological data both individually and collectively.
All clustering analyses resulted in the significant identification of patient classes, with the pure biological classes derived from patient blood and dura mater samples demonstrating the strongest evidence. Those patient classes were further characterized by identifying enriched biological pathways, as well as correlated cranial base morphological and clinical traits.
Our results implicate several strong biological candidates warranting further investigation from the dura expression analysis and also identified a blood gene expression profile corresponding to a global down-regulation in protein synthesis.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The purpose of this study is to retrospectively review our experience with stent-assisted embolization of patients with an acutely ruptured cerebral aneurysm.
Medical records and imaging were ...reviewed for 36 patients who underwent stent-assisted embolization of a ruptured cerebral aneurysm.
Seventeen patients (47%) received a preprocedural loading dose of clopidogrel and five patients (14%) received an intraprocedural dose of clopidogrel. The remaining 14 patients (36%) were treated with antiplatelet therapy following the procedure. Six (17%) stent related intraprocedural thromboembolic complications were encountered; four of these resolved (one partial, three complete) following treatment with abciximab and/or heparin during the procedure. Five of the six thromboembolic events occurred in patients who were not pretreated with clopidogrel (P = 0.043). Two patients in this series (6%) had a permanent thrombotic complication resulting in mild hemiparesis in one patient, and hemianopsia in the second. No procedure related hemorrhagic complications occurred in any patient. One patient had a spontaneous parenchymal hemorrhage contralateral to the treated aneurysm discovered 10 days after treatment. Twenty-eight patients (78%) had a Glasgow Outcome Score of 4 or better at discharge. Seven of 21 patients (33%) with angiographic follow-up required further treatment of the coiled aneurysm.
Stent-assisted coil embolization is an option for treatment of ruptured wide neck ruptured aneurysms and for salvage treatment during unassisted embolization of ruptured aneurysms but complications and retreatment rates are higher than for routine clipping or coiling of cerebral aneurysms. Pretreatment with clopidogrel appears effective in reducing thrombotic complications without significant increasing risk of hemorrhagic complications.
Summary
Chiari Type I Malformation (CMI) is characterized by herniation of the cerebellar tonsils through the base of the skull. Although cerebellar tonsillar herniation (CTH) is hypothesized to ...result from an underdeveloped posterior cranial fossa (PF), patients are frequently diagnosed by the extent of CTH without cranial morphometric assessment. We recently completed the largest CMI whole genome qualitative linkage screen to date. Despite an initial lack of statistical evidence, stratified analyses using clinical criteria to reduce heterogeneity resulted in a striking increase in evidence for linkage. The present study focused on the use of cranial base morphometrics to further dissect this heterogeneity and increase power to identify disease genes. We characterized the genetic contribution for a series of PF traits and evaluated the use of heritable, disease‐relevant PF traits in ordered subset analysis (OSA). Consistent with a genetic hypothesis for CMI, much of the PF morphology was found to be heritable and multiple genomic regions were strongly implicated from OSA, including regions on Chromosomes 1 (LOD = 3.07, p = 3 × 10−3) and 22 (LOD = 3.45, p = 6 × 10−5) containing several candidates warranting further investigation. This study underscores the genetic heterogeneity of CMI and the utility of PF traits in CMI genetic studies.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
The effect of vessel patency, following recombinant tissue plasminogen activator (rtPA) administration, on clinical outcome in acute ischemic stroke (AIS) has been controversial. We studied the ...effect of recanalization following intraarterial (IA) and intravenous/IA (IV/IA) rtPA on clinical outcome in AIS.
Recanalization was classified angiographically as complete (as compared with unoccluded vessel, thrombolysis in myocardial infarction classification TIMI 3), none (with no change from prethrombolysis, TIMI 0), and partial (when a change in the flow from baseline was noted, TIMI 1-2). Outcomes were symptomatic intracranial hemorrhage (sICH), 90-day modified Rankin scale (< or = 2 as a good outcome), and 3-month mortality.
Ninety-six patients had either combined IV/IA (41) or IA (55) rtPA for AIS during a 7-year period. Any recanalization occurred in 69%; 55% of those had a good outcome versus 23% in the rest (Odds ratio = 3.9; 95% confidence interval CI = 1.4-11.2; P = .007). Only 24% had complete recanalization; 74% had a good outcome versus 36% in the nonrecanalization group (OR = 5.1; 95% CI = 1.6-16.8; P = .002). When adjusted to time to therapy and vessel occluded, these results lessened but remained significant. The sICH rate with any recanalization was 7.6% versus 13.3% in patients with persistent clot (relative risk (RR) = 0.6; 95% CI = 0.2-2.0; P = .45). Death occurred in 19.7% of those whose vessels recanalized versus 33.3% in the rest (RR = 0.56; 95% = 0.26-1.19; P = .2).
A total of 24% and 69% of patients had complete and any recanalization, respectively, following endovascular rtPA therapy of AIS. The degree of recanalization was directly related to time to therapy and associated with good clinical outcome without an increase in the rate of adverse effect.
Computed tomography angiography (CTA) is a rapidly developing technology with great potential. This is particularly true for evaluating neurovascular disease. Clinical stroke because of ...atherosclerotic disease of the carotid and vertebral arteries is a common examination indication; areas of stenosis, and soft and calcified plaque along the entire vessel, not only at the carotid bifurcation, permit a full assessment of the patient’s disease process. Other diseases including dissection, trauma, intracranial stenosis, thrombosis, and aneurysms can be readily diagnosed. Although duplex ultrasound may be a first line examination in many patients, both magnetic resonance angiography (MRA) and CTA offer distinct advantages over it. CTA and MRA are both highly accurate but CTA has several key advantages. CTA has been advanced by the development of improved multidetector CT (MDCT) and workstations that postprocess the data. Methods to obtain quality CTA images and to rapidly analyze the data for abnormalities are the subject of this chapter. In addition, evolving techniques in future CT scanners and workstations, and developing methods of vulnerable plaque and CT perfusion imaging are discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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