Spine trauma. American College of Radiology. ACR Appropriateness Criteria.
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Cervical Vertebrae↗
Biomedical subjects
P C Davis
Publications and source records attributed to P C Davis.
Neurodegenerative disorders. American College of Radiology. ACR Appropriateness Criteria.
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Brain↗
Analysis and pharmacokinetics of quetiapine and two metabolites in human plasma using reversed-phase HPLC with ultraviolet and electrochemical detection.
A sensitive and specific HPLC assay for the measurement of the antipsychotic compound quetiapine in human plasma has been developed and validated. The assay employs a three-step liquid liquid extraction of quetiapine and its 7-hydroxylated and 7-hydroxylated, N-dealkylated metabolites from human plasma, and utilizes ultraviolet (UV) detection of quetiapine and electrochemical detection of the metabolites. The method provides a linear response from a quantitation limit of 2.50 to 500 ng ml(-1) for each analyte using 0.4 ml plasma. The assay is applicable from 500 to 5000 ng ml(-1) by sample dilution with de-ionized water. The inter-assay precision of quetiapine in plasma calibration standards across 4 validation days averaged 11.9% relative standard deviation (RSD) over the range 2.50 to 500 ng ml(-1), with intra-assay precision averaging 16.0% RSD and mean accuracy of 98.6% of theory. Similarly, the inter-assay precision of the 7-hydroxylated metabolite in plasma calibration standards across 4 validation days averaged 13.7% RSD over the range 2.50 to 500 ng ml(-1), with intra-assay precision averaging 17.6% RSD and mean accuracy of 109% of theory. The 7-hydroxylated, N-dealkylated metabolite demonstrated inter-assay precision of 16.2% RSD, intra-assay precision of 19.9% RSD, and mean accuracy of 104% of theory over the range 2.50 to 500 ng ml(-1). The present assay method was used to support a study comparing the pharmacokinetic profile of quetiapine with the time course of dopamine D2 and serotonin 5-HT2 receptor occupancy in the brain using positron emission tomography (PET). We describe in this paper the bioanalytical method and the plasma concentrations of quetiapine and its metabolites resulting from this study.
Adult↗
Sedation for pediatric imaging studies.
This article discusses safe sedation for pediatric imaging. Emphasis is placed upon implementation of an institutional sedation program according to guidelines of the American Academy of Pediatrics. Standards for patient assessment and preparation, sedative administration, monitoring, and discharge are reviewed. A comparison of available sedative agents is also provided.
Anesthesia Recovery Period↗
Imaging of the pediatric orbit and visual pathways: computed tomography and magnetic resonance imaging.
Techniques for pediatric MR imaging and computed tomography and anatomy of the orbit and intracranial visual pathways are presented and reviewed in this article. Imaging findings are presented for the following categories of abnormality: a) orbital anomalies related to congenital disorders of the brain, b) disorders of the orbit (ocular, nonocular, or multicompartmental), c) disorders of the intracranial visual pathways (suprasellar cistern, optic radiations, or occipital cortex), and d) disorders of gaze (extraocular muscles, cranial nerves, and brainstem). Careful assessment of the clinical findings, anatomic location of the visual impairment, and familiarity with disorders that often affect pediatric patients are helpful in guiding neuroimaging evaluation of the child with ocular, orbital, or central patterns of visual disturbance.
Brain Diseases↗
Intracranial aneurysms in infants and children.
BACKGROUND: The diagnosis and imaging of pediatric aneurysms has changed since the advent of MR and MRA. OBJECTIVE: To update the literature on pediatric aneurysms and better define the appropriate work-up of childhood aneurysms in 1997. MATERIALS AND METHODS: Retrospective review of 21 children (12 boys, 9 girls) with 25 aneurysms from three institutions over a 20-year period was performed. Imaging studies were mixed and included CT (19 patients), MR (11 patients), MRA (6 patients) and angiography (18 patients). RESULTS: Eighteen of 25 aneurysms were congenital saccular, 6 were mycotic, and 1 was post-traumatic. Of these, 44 % were in the posterior circulation. Nine aneurysms arose from distal arterial branches. Forty percent were large (between 1-2.5 cm) and 16 % were giant (> 2.5 cm). CT and MR showed hemorrhage, and frequently revealed the aneurysms as a focal mass with or without enhancement and flow void. Six children had MRA which revealed aneurysms in four patients. All patients with MRA had corresponding conventional angiography. CONCLUSION: Characteristics of pediatric aneurysms include diversity of type, increased incidence in the posterior fossa, peripheral location, and large size. CT, MR and MRA are useful in the diagnosis with conventional angiography essential for preoperative planning.
Adolescent↗
Hypersensitivity reactions to Escherichia coli-derived polyethylene glycolated-asparaginase associated with subsequent immediate skin test reactivity to E. coli-derived granulocyte colony-stimulating factor.
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Anaphylaxis↗
MOPP or radiation in addition to ABVD in the treatment of pathologically staged advanced Hodgkin's disease in children: results of the Children's Cancer Group Phase III Trial.
PURPOSE: A randomized trial designed to compare mechlorethamine, vincristine, procarbazine, and prednisone (MOPP)/doxorubicin, bleomycin, vinblastine, and daccarbazine (ABVD) (regimen A) with ABVD plus low-dose regional (extended-field) radiation therapy (EF RT) (regimen B) for the treatment of children and adolescents with stages III and IV Hodgkin's disease was conducted by the Children's Cancer Group (CCG-521) from 1986 until 1990. PATIENTS AND METHODS: One hundred eleven eligible patients were randomized, 57 to regimen A and 54 to regimen B. All patients had pathologically verified stage III or stage IV Hodgkin's disease. RESULTS: Overall survival (S) is 87% at 4 years and event-free survival (EFS) is 82%. Patients randomized to ABVD plus EF RT have a 4-year EFS of 87% compared with 77% for patients randomized to MOPP/ABVD (P = .09, two-sided). Patients randomized to ABVD plus EF RT have a 4-year S of 90% compared with 84% for patients randomized to MOPP/ABVD (P = .45, two-sided). Significant prognostic factors in multivariate analysis for EFS are stage of disease, erythrocyte sedimentation rate (ESR) at diagnosis, liver size at diagnosis, and, among stage III patients, the size of the mediastinal mass at diagnosis. The acute toxicities of treatment are largely hematopoietic in nature, whereas acute pulmonary and cardiac toxicities are modest and not limiting. CONCLUSION: The results of this study show that, in advanced-stage Hodgkin's disease in children, equivalent results can be obtained by the addition of either MOPP or low-dose EF RT to the ABVD regimen; whether the addition of either contributes to outcome was not addressed in this study and will require additional testing. It is clear, however, that MOPP chemotherapy can safely be eliminated from front-line combination chemotherapy regimens for advanced Hodgkin's disease in pediatric patients.
Adolescent↗
Inversion-recovery echo-planar MR in adult brain neoplasia.
PURPOSE: A T1-weighted multishot inversion-recovery (IR) echo-planar MR imaging (EPI) sequence was developed to improve intracranial tissue differentiation; its diagnostic utility was compared with that of conventional axial T1-weighted spin-echo and axial T2-weighted turbo spin-echo sequences. METHODS: Eighteen patients with known or suspected primary or metastatic brain neoplasia were imaged in a 1.5-T unit with IR-EPI sequences. Three observers measured gray/white matter contrast-to-noise ratios and subjectively compared IR-EPI sequences with T1-weighted spin-echo and T2-weighted turbo spin-echo sequences for gray/white matter discrimination, visibility of intracranial and vascular structures, overall lesion conspicuity, size of lesion(s), and presence and severity of artifacts. RESULTS: Twenty-four lesions (including neoplasia, infarction, treatment-associated encephalomalacia, nonneoplastic white matter signal abnormalities, and basilar artery dolichoectasia) were detected in 12 patients. Basilar artery dolichoectasia was not included in subsequent statistical analysis. Pulsatile flow artifacts were markedly reduced on IR-EPI sequences relative to those on T1-weighted spin-echo sequences. Gray/white matter contrast was greater on IR-EPI images than on T1-weighted spin-echo images. Periaqueductal gray matter, basal ganglia, optic tracts, cranial nerve V, and claustrum were seen better or as well on IR-EPI images as compared with T1-weighted spin-echo images. IR-EPI was more sensitive to magnetic sensitivity effects, with resultant decreased visibility of cranial nerves VII and VIII and the orbital portion of the optic nerves. For noncontrast sequences, lesion conspicuity was better on IR-EPI images than on T1-weighted spin-echo images in 16 (70%) of 23 lesions and was equal on the two sequences in seven (30%) of 23 lesions. Lesion size, including surrounding edema, was greater on IR-EPI images than on T2-weighted turbo spin-echo images in two (9%) of 23 cases and equal in 21 (91%) of 23 cases. Hyperintense foci of methemoglobin were more conspicuous on T1-weighted spin-echo images. CONCLUSION: Multishot IR-EPI is superior to conventional T1-weighted spin-echo imaging for parenchymal tissue contrast and lesion conspicuity, and is equal to T2-weighted turbo spin-echo imaging in sensitivity to pathologic entities.
Adult↗
Treatment of brain tumors in children is associated with abnormal MR spectroscopic ratios in brain tissue remote from the tumor site.
PURPOSE: Children who have brain tumors are at risk for a variety of treatment-related sequelae, including neuropsychological and cognitive impairment, neurologic deficits, and neuroendocrinologic disturbances. We sought to determine the value of proton MR spectroscopy in assessing brain tissue remote from the tumor site to ascertain the effects of chemotherapy and radiation treatment in these patients. METHODS: Single-voxel proton MR spectra from 70 patients (111 spectra) and 11 healthy volunteers (11 spectra) were analyzed. NAA/Cr, NAA/Cho, and Cho/Cr ratios based on peak areas were obtained from nonneoplastic regions of the frontal lobe. The relationship between MR spectroscopic ratios and treatment was determined. RESULTS: NAA-containing ratios were decreased in patients as compared with control subjects. The presence of gadolinium-based contrast material did not cause significant changes in the ratios as compared with precontrast data. When chemotherapy was a component of a child's treatment protocol, we found a significant decline in NAA/Cr ratios. Patients who underwent both chemotherapy and radiation therapy showed a trend toward lower NAA-containing ratios if the chemotherapy was administered before the radiation therapy. Patients receiving whole-brain radiation had a trend toward lower NAA-containing ratios than did those who had only focal tumor treatment. CONCLUSION: In children with brain tumors, MR spectroscopy of brain tissue remote from the tumor reveals treatment-related biochemical changes.
Adolescent↗
Moyamoya disease in the United States.
The epidemiology and radiological features of Moyamoya disease (MMD) in the US were investigated. This study encompassed 98 cases; 26 were newly collected from eight US institutions and 72 were previously reported in the US literature. The patients ranged in age from 6 months to 67 years with age peaks in the first, third and fourth decades. MMD was seen in various ethnic groups and females were more commonly involved (71%) than males. A specific etiology could not be determined in most cases but arteriosclerosis and use of oral contraceptives were occasional associations. On angiography and/or magnetic resonance angiography (MRA), carotid arterial stenosis or occlusion was seen bilaterally in 95 cases (97%) and unilaterally in three. On MR or MRA, internal carotid steno-occlusive lesions were well demonstrated in all cases but Moyamoya collateral vessels (MMVs) were visualized in only 65% of the patients. MMVs in the basal ganglia and thalami were best demonstrated on T1 weighted images. Parenchymal lesions were seen in all patients and were often bilateral. With advances in MR techniques and increasing awareness of diagnostic guidelines, MMD will be diagnosed more frequently than before in the US.
Adolescent↗
Anemia in a patient with panhypogammaglobulinemia.
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Agammaglobulinemia↗
Optic nerve hypoplasia: absence of posterior pituitary bright signal on magnetic resonance imaging correlates with diabetes insipidus.
PURPOSE: Magnetic resonance imaging has been used to examine children with optic nerve hypoplasia for pituitary abnormalities who may be at risk for anterior pituitary hormonal deficiencies. We correlated the sellar and optic pathway anatomic findings on magnetic resonance imaging in children with optic nerve hypoplasia with findings from their endocrinologic and ophthalmologic examinations to determine whether magnetic resonance imaging findings predict anterior and posterior pituitary dysfunction. METHODS: A retrospective review identified five children with optic nerve hypoplasia and endocrinopathy who also underwent high resolution volumetric magnetic resonance imaging. RESULTS: All children had severe bilateral optic nerve hypoplasia and anterior pituitary hormone deficiencies. Three children had no recognizable intrasellar or ectopic posterior pituitary bright spot on magnetic resonance imaging; all had clinical evidence of diabetes insipidus. Two patients with a recognizable but ectopic posterior pituitary did not have diabetes insipidus. CONCLUSION: Children with optic nerve hypoplasia and no recognizable posterior lobe of the pituitary gland on magnetic resonance imaging are at risk for both anterior and posterior pituitary dysfunction, whereas those with a posterior lobe on magnetic resonance imaging appear to have intact posterior pituitary function.
Diabetes Insipidus↗
Advances in neuroimaging of the visual pathways.
PURPOSE: To provide a practical review for the ophthalmologist of advances in neuroimaging of the visual pathways. METHODS: We reviewed recent advances in computed tomography, magnetic resonance imaging, and angiography that are applicable to visual pathways imaging. RESULTS: For detailed ocular imaging, computed tomography complements ocular sonography for imaging of calcification, trauma, and masses. Magnetic resonance imaging may be helpful for localization and characterization of ocular masses in the setting of hemorrhage. For orbital imaging, computed tomography is most appropriate in the evaluation of suspected thyroid ophthalmopathy, infection, and trauma; otherwise, either computed tomography or magnetic resonance imaging is useful for detection and characterization of abnormality. For disorders affecting the sellar, retrochiasmal, and brainstem pathways, magnetic resonance imaging is the study of choice, except for acute hemorrhage, for which noncontrast computed tomography is preferable. Although magnetic resonance angiography has a role in the elective evaluation of cerebrovascular disease, conventional angiography is the definitive study for suspected aneurysm and for surgical planning. CONCLUSIONS: A practical approach for selection of the most appropriate imaging modalities by the ophthalmologist is suggested on the basis of the anatomic location and type of disease suspected.
Adult↗
Tntraoperative vesical pressure measurements as a guide in the closure of abdominal wall defects.
Increased intra-abdominal pressure represents a difficult problem when closing abdominal wall defects (AWD) and can cause renal insufficiency and vascular injury to the intestine with the development of necrotizing enterocolitis. Urinary bladder pressure measurements have been shown to accurately reflect intra-abdominal pressure in animal models. This study compares outcomes with and without vesical pressure measurements in AWD. Since its description in 1987, these vesical pressure measurements have guided the closure of AWDs. A pressure of <20 cm H2O allows closure by primary fascial, skin, or staged prosthetic closure. All charts of patients who underwent AWD closure from 1981 to 1993 were reviewed and data collected including type of defect and closure, gestational age, weight, age at operation, fluid requirements and urinary outputs, ventilator requirements, days to first and total feeding, total parenteral nutrition (TPN) days, hospital days, hospital charges, morbidity, and mortality. Results were analyzed by paired or unpaired Student's t test or Fisher's exact test. Twenty-seven infants did not receive vesical pressure measurements, whereas 13 did. No significant differences occurred in the parameters recorded in these two diverse groups. When gastroschisis patients only were compared, a significant decrease in intravenous fluid requirements in the vesical measurement group occurred on postoperative Day 2 (155.3+/- 37.5 versus 109.6 +/- 34.3; P = 0.016), and a significant decrease in urinary output occurred on postoperative Day 3 (4.2 +/- 112 versus 3.1+/- 1.1; P=0.044). Ventilator support, TPN days, and oral feeding data were all lower in the vesical measurement group but did not reach statistical significance. Hospital days and hospital changes showed a trend to lower values in the measured group (P values 0.052 and 0.095, respectively). Intraoperative vesical pressure measurements represent a simple, safe, effective method to guide the closing of AWD and result in less capillary leak and more prompt diuresis, and may result in significantly less morbidity, mortality, and cost.
Abdomen↗
MR of the brain in children.
MR imaging has firmly established its place as the cornerstone of pediatric neuroimaging. Recent advances in MR imaging have led to decreased imaging time, high resolution studies, and new methods for obtaining tissue contrast. Magnetic resonance angiography (MRA) now obviates the need for angiography in some children, although its extended role is still to be defined. Normal and abnormal development and myelination patterns have been further defined with MR imaging. The patterns of brain injury resulting from hypoxia and ischemia vary with the degree of the insult as well as the gestational age of the child. These patterns of hypoxic-ischemic encephalopathy can be analyzed to determine when the insult occurred. Neuronal migration disorders and phakomatoses can be diagnosed with confidence at an early age, thus facilitating genetic counseling. MR imaging can detect the most common lesions associated with childhood epilepsy, such as hippocampal sclerosis, focal cortical dysplasias, and low-grade tumors. Other areas, including pediatric AIDS, toxicity-related injury, metabolic/mitochondrial conditions, and disorders associated with iatrogenic injury, can be diagnosed with MR. Spectroscopy provides information that should prove useful in evaluating and monitoring neuronal and other brain tissue disorders in children.
Brain↗
Adult cerebrovascular disease: role of modified rapid fluid-attenuated inversion-recovery sequences.
PURPOSE: To compare a rapid fluid-attenuated inversion-recovery (FLAIR) sequence with T1-weighted, fast spin-echo proton density-weighted, and T2-weighted images in the evaluation of cerebrovascular disease. METHODS: All patients underwent standard T1-, proton density-, and T2-weighted fast spin-echo and fast FLAIR MR imaging at 1.5 T. Images were compared for lesion size, location, and conspicuity. RESULTS: Forty-five infarctions were identified on T2-weighted and fast FLAIR sequences. Lesion size was comparable on the proton density-weighted, fast T2-weighted, and fast FLAIR sequences, although lesion conspicuity was superior on the fast FLAIR images in 43 (96%) of the lesions. Associated periventricular and pontine hyperintensities were more extensive on the fast FLAIR images. CONCLUSION: Our modified fast FLAIR technique provided improved conspicuity of infarctions and white matter disease as compared with T1-, proton density-, and T2-weighted spin-echo images, and a reduced scan time compared with conventional FLAIR sequences in patients with cerebrovascular disease.
Adult↗