Alexander B Baxter, M.D.

Single spiral sweep: Emergency evaluation of the head & face, and head, face & cervical spine
McMenamy J.; Bernstein M.; Baxter A.
2011 ;18(6):454-454, Emergency radiology
Purpose: A pilot study was performed to assess the feasibility of a single pass spiral technique to image the head and face, or head, face, and cervical spine in the emergency setting. Materials and Methods: 23 patients requiring emergency imaging of head, face and cervical spine, and 5 patients for head and face were enrolled. Radiation dose (DLP) was measured and compared with isolated CT head and face and cervical spine acquisitions. Time to perform the single spiral scan was also measured. The quality of spiral CT heads was compared with 21 consecutive trauma axial CT heads on a five point scale in a blinded fashion. Results: Average DLP for single spiral CT head, face, and cervical spine was 2581.24, compared with DLP of 2867.22 for these performed separately. Average DLP for single pass head and face (including mandible) CT was 1749.45, compared with standard 2 scan DLP of 1887.81. Time to scan a single pass CT head, face, and cervical spine ranged from 4.4 to 5.8 s. Quality of spiral head CTcomparedwith axial in trauma patients showed no significant difference. Conclusion: Single pass emergency CT head & face, and head, face, & cervical spine is both time and radiation efficient without reduction in image quality
— id: 147748, year: 2011, vol: 18, page: 454, stat: Journal Article,

Potentially life-saving role for temporary endovascular balloon occlusion in atypical mediastinal hematoma
Desai, Muneer; Baxter, Alexander B; Karmy-Jones, Riyad; Borsa, John J
2002 May;178(5):1180-1180, American journal of roentgenology
— id: 42752, year: 2002, vol: 178, page: 1180, stat: Journal Article,

Radiologic and clinical spectrum of occipital condyle fractures: retrospective review of 107 consecutive fractures in 95 patients
Hanson, Julian A; Deliganis, Anastasia V; Baxter, Alexander B; Cohen, Wendy A; Linnau, Ken F; Wilson, Anthony J; Mann, F A
2002 May;178(5):1261-1268, American journal of roentgenology
OBJECTIVE: We proposed to characterize the radiologic spectrum of occipital condyle fractures in a large series of patients and to correlate fracture pathology with neurosurgical treatment and patient outcome. MATERIALS AND METHODS: We conducted a retrospective review of the findings on conventional radiography, CT, and MR imaging in 95 patients with 107 occipital condyle fractures. We described fracture patterns according to two previously published classification systems. Clinical findings, neurosurgical management, and patient outcome were obtained from the medical records. RESULTS: Inferomedial avulsions (Anderson and Montesano type III) were the most common type of occipital condyle fracture, constituting 80 (75%) of 107 overall fractures. Unilateral occipital condyle fractures were found in 73 (77%) of 95 patients, and 58 patients were treated nonoperatively; occipitocervical fusion was required in nine patients for complex C1-C2 injuries, and six patients died. Bilateral occipital condyle fractures or occipitoatlantoaxial joint injuries were seen in 22 (23%) of 95 patients. Occipitocervical fusion or halo traction for the craniocervical junction was required in 12 patients, all of whom had CT evidence of bilateral occipitoatlantoaxial joint disruption and six of whom showed normal craniocervical relationships on conventional radiographs. Six patients with nondisplaced fractures were treated nonoperatively, and four patients died. Thirty (32%) of 95 patients showed continued disability, whereas 55 (57.5%) of 95 patients had good outcomes at 1 month. Associated cervical spine injuries were present in 29 (31%) of 95 patients. CONCLUSION: Given their associated traumatic brain and cervical spine injuries, occipital condyle fractures are markers of high-energy traumas. That conventional radiographs alone may miss up to half of the patients with acute craniocervical instability has not been well established. Avulsion fracture type and fracture displacement are associated with both injury mechanism and the need for surgical stabilization. In this series, most unilateral occipital condyle fractures were treated nonoperatively, whereas bilateral occipitoatlantoaxial joint injuries with findings of instability usually required surgical stabilization
— id: 42751, year: 2002, vol: 178, page: 1261, stat: Journal Article,

Withdrawal of support in intracerebral hemorrhage may lead to self-fulfilling prophecies
Becker KJ; Baxter AB; Cohen WA; Bybee HM; Tirschwell DL; Newell DW; Winn HR; Longstreth WT Jr
2001 Mar 27;56(6):766-772, Neurology
BACKGROUND: Withdrawal of support in patients with severe brain injury invariably leads to death. Preconceived notions about futility of care in patients with intracerebral hemorrhage (ICH) may prompt withdrawal of support, and modeling outcome in patient populations in whom withdrawal of support occurs may lead to self-fulfilling prophecies. METHODS: Subjects included consecutive patients with supratentorial ICH. Radiographic characteristics of the hemorrhage, clinical variables, and neurologic outcome were assessed. Attitudes about futility of care were examined among members of the departments of neurology and neurologic surgery through a written survey and case presentations. RESULTS: There were 87 patients with supratentorial ICH; overall mortality was 34.5% (30/87). Mortality was 66.7% (18/27) in patients with Glasgow Coma Score < or = 8 and ICH volume > 60 cm(3). Medical support was withdrawn in 76.7% (23/30) of patients who died. Inclusion of a variable to account for the withdrawal of support in a model predicting outcome negated the predictive value of all other variables. Patients undergoing surgical decompression were unlikely to have support withdrawn, and surgery was less likely to be performed in older patients (p < 0.01) and patients with left hemispheric hemorrhage (p = 0.04). Survey results suggested that practitioners tend to be overly pessimistic in prognosticating outcome based upon data available at the time of presentation. CONCLUSIONS: The most important prognostic variable in determining outcome after ICH is the level of medical support provided. Withdrawal of support in patients felt likely to have a 'poor outcome' biases predictive models and leads to self-fulfilling prophecies. Our data show that individual patients in traditionally 'poor outcome' categories can have a reasonable neurologic outcome when treated aggressively
— id: 42754, year: 2001, vol: 56, page: 766, stat: Journal Article,

Herpes simplex virus encephalitis complicating myxedema coma treated with corticosteroids
Doherty MJ; Baxter AB; Longstreth WT Jr
2001 Apr 24;56(8):1114-1115, Neurology
— id: 42753, year: 2001, vol: 56, page: 1114, stat: Journal Article,

Lateral radiography of the cervical spine in the trauma patient: looking beyond the spine
Perry JR; Stern EJ; Mann FA; Baxter AB
2001 Feb;176(2):381-386, American journal of roentgenology
— id: 42755, year: 2001, vol: 176, page: 381, stat: Journal Article,

Radiologic spectrum of craniocervical distraction injuries
Deliganis AV; Baxter AB; Hanson JA; Fisher DJ; Cohen WA; Wilson AJ; Mann FA
2000 Oct;20 Spec No(2):S237-S250, Radiographics
Injuries to the atlanto-occipital region, which range from complete atlanto-occipital or atlantoaxial dislocation to nondisplaced occipital condyle avulsion fractures, are usually of critical clinical importance. At initial cross-table lateral radiography, measurement of the basion-dens and basion-posterior axial line intervals and comparison with normal measurements may help detect injury. Computed tomography (CT) with sagittal and coronal reformatted images permits optimal detection and evaluation of fracture and luxation. CT findings that may suggest atlanto-occipital injury include joint incongruity, focal hematomas, vertebral artery injury, capsular swelling, and, rarely, fractures through cranial nerve canals. Magnetic resonance (MR) imaging of the cervical spine with fat-suppressed gradient-echo T2-weighted or short-inversion-time inversion recovery sequences can demonstrate increased signal intensity in the atlantoaxial and atlanto-occipital joints, craniocervical ligaments, prevertebral soft tissues, and spinal cord. Axial gradient-echo MR images may be particularly useful in assessing the integrity of the transverse atlantal ligament. All imaging studies should be conducted with special attention to bone integrity and the possibility of soft-tissue injury. Atlanto-occipital injuries are now recognized as potentially survivable, although commonly with substantial morbidity. Swift diagnosis by the trauma radiologist is crucial for ensuring prompt, effective treatment and preventing delayed neurologic deficits in patients who survive such injuries
— id: 42756, year: 2000, vol: 20 Spec No, page: S237, stat: Journal Article,

Traumatic ossicular disruption
Li ST; Baxter AB
2000 May;174(5):1296-1296, American journal of roentgenology
— id: 42757, year: 2000, vol: 174, page: 1296, stat: Journal Article,

Extravasation of radiographic contrast is an independent predictor of death in primary intracerebral hemorrhage
Becker KJ; Baxter AB; Bybee HM; Tirschwell DL; Abouelsaad T; Cohen WA
1999 Oct;30(10):2025-2032, Stroke
BACKGROUND AND PURPOSE: Hematomas that enlarge following presentation with primary intracerebral hemorrhage (ICH) are associated with increased mortality, but the mechanisms of hematoma enlargement are poorly understood. We interpreted the presence of contrast extravasation into the hematoma after CT angiography (CTA) as evidence of ongoing hemorrhage and sought to identify the clinical significance of contrast extravasation as well as factors associated with the risk of extravasation. METHODS: We reviewed the clinical records and radiographic studies of all patients with intracranial hemorrhage undergoing CTA from 1994 to 1997. Only patients with primary ICH were included in this study. Univariate and multivariate logistic regression analyses were performed to determine the associations between clinical and radiological variables and the risk of hospital death or contrast extravasation. RESULTS: Data were available for 113 patients. Contrast extravasation was seen in 46% of patients at the time of CTA, and the presence of contrast extravasation was associated with increased fatality: 63.5% versus 16.4% in patients without extravasation (P=0.011). There was a trend toward a shorter time (median+/-SD) from symptom onset to CTA in patients with extravasation (4.6+/-19 hours) than in patients with no evidence of extravasation (6.6+/-28 hours; P=0.065). Multivariate analysis revealed that hematoma size (P=0.022), Glasgow Coma Scale (GCS) score (P=0.016), extravasation of contrast (P=0.006), infratentorial ICH (P=0.014), and lack of surgery (P<0.001) were independently associated with hospital death. Variables independently associated with contrast extravasation were hematoma size (P=0.024), MABP >120 mm Hg (P=0.012), and GCS score of </=8 (P<0.005). CONCLUSIONS: Contrast extravasation into the hematoma after ICH is associated with increased fatality. The risk of contrast extravasation is increased with extreme hypertension, depressed consciousness, and large hemorrhages. If contrast extravasation represents ongoing hemorrhage, the findings in this study may have implications for therapy of ICH, particularly with regard to blood pressure management
— id: 42758, year: 1999, vol: 30, page: 2025, stat: Journal Article,

Delayed cerebral artery pseudoaneurysm after nail gun injury
Blankenship BA; Baxter AB; McKahn GM 2nd
1999 Feb;172(2):541-542, American journal of roentgenology
— id: 42761, year: 1999, vol: 172, page: 541, stat: Journal Article,

Internal carotid pseudoaneurysm and cerebral infarction from shotgun pellet penetration and embolization
Song JK; Srinivasan J; Gordon DS; Newell DW; Baxter AB
1999 Oct;173(4):1116-1116, American journal of roentgenology
— id: 42759, year: 1999, vol: 173, page: 1116, stat: Journal Article,

Orbital assault with a pencil: evaluating vascular injury
Tenenholz T; Baxter AB; McKhann GM
1999 Jul;173(1):144-144, American journal of roentgenology
— id: 42760, year: 1999, vol: 173, page: 144, stat: Journal Article,

Imaging of intracranial aneurysms and subarachnoid hemorrhage
Baxter AB; Cohen WA; Maravilla KR
1998 Jul;9(3):445-462, Neurosurgery clinics of North America
Advances in CT, MR imaging, and catheter angiography provide the radiologist and neurosurgeon with a variety of imaging options for screening, diagnosis, presurgical evaluation, and postoperative monitoring of patients with intracranial aneurysms. Noninvasive imaging techniques have not replaced conventional angiography for the comprehensive evaluation o aneurysms but are effective in screening patients suspected to have an unruptured aneurysm or for preoperative planning in emergency situations that preclude catheter angiography. CT, CT angiography, MR imaging, and MR angiography can all complement the information obtained with catheter angiography in presurgical planning, and the choice of supplemental studies should be individualized. Rotational and intraoperative angiography are problem-solving options used for selected cases at our institution. Continuous improvements in techniques for CT and MR angiography may someday reach the point where surgery can be undertaken on the basis on noninvasive imaging alone, with catheter angiography reserved for endovascular therapy planning and guidance
— id: 42762, year: 1998, vol: 9, page: 445, stat: Journal Article,

Cerebral infarct in a victim of vehicular polytrauma
Baxter AB; Nevitt AW; Britz GW
1998 Feb;170(2):506-506, American journal of roentgenology
— id: 42763, year: 1998, vol: 170, page: 506, stat: Journal Article,

RadNotes: a novel software development tool for radiology education
Baxter AB; Klein JS; Oesterle EV
1997 May-Jun;17(3):761-767, Radiographics
RadNotes is a novel software development tool that enables physicians to develop teaching materials incorporating text and images in an intelligent, highly usable format. Projects undertaken in the RadNotes environment require neither programming expertise nor the assistance of a software engineer. The first of these projects, Thoracic Imaging, integrates image teaching files, concise disease and topic summaries, references, and flash card quizzes into a single program designed to provide an overview of chest radiology. RadNotes is intended to support the academic goals of teaching radiologists by enabling authors to create, edit, and electronically distribute image-oriented presentations. RadNotes also supports the educational goals of physicians who wish to quickly review selected imaging topics, as well as to develop a visual vocabulary of corresponding radiologic anatomy and pathologic conditions. Although Thoracic Imaging was developed with the aim of introducing chest radiology to residents, RadNotes can be used to develop tutorials and image-based tests for all levels; create corresponding World Wide Web sites; and organize notes, images, and references for individual use
— id: 42764, year: 1997, vol: 17, page: 761, stat: Journal Article,

Serial MR in gene therapy for recurrent glioblastoma: initial experience and work in progress
Deliganis AV; Baxter AB; Berger MS; Marcus SG; Maravilla KR
1997 Sep;18(8):1401-1406, AJNR. American journal of neuroradiology
PURPOSE: To describe the MR imaging findings in a pilot study evaluating gene therapy for treatment of patients with recurrent glioblastoma. METHODS: Serial MR examinations were evaluated retrospectively in patients treated with gene therapy that included a retroviral vector containing the herpes simplex virus thymidine kinase gene and intravenous ganciclovir. Images were obtained after tumor resection and after each cycle of treatment, at approximately 40-day intervals. The volume of enhancing tissue was measured on serial MR images. RESULTS: Eleven patients with recurrent glioblastoma were entered into the clinical trial of gene therapy and seven patients completed at least two cycles of treatment. Of these seven, three patients had an early (between 40 and 80 days) increase in the volume of enhancing tissue followed by a decrease or plateau in enhancing tissue volume. A fourth patient had a stable volume of enhancing tissue for 132 days. The remaining three patients had continuous increases in volume of enhancement on all subsequent MR examinations. CONCLUSION: Although animal data show striking tumor regression in response to similar gene therapy, only limited regression was observed among the seven patients we studied. The transient increases in enhancement seen in three of seven patients might reflect an inflammatory response to local injection of the viral vector
— id: 9019, year: 1997, vol: 18, page: 1401, stat: Journal Article,

In vitro histamine release induced by magnetic resonance imaging and iodinated contrast media
Baxter AB; Lazarus SC; Brasch RC
1993 Apr;28(4):308-312, Investigative radiology
RATIONALE AND OBJECTIVES. To investigate the mechanism of anaphylactoid reactions to contrast media, in vitro histamine release induced by magnetic resonance imaging, and iodinated contrast agents was examined in a dog mastocytoma cell line. METHODS. Two gadolinium (Gd)-based magnetic resonance contrast agents, Gd diethylenetriamine pentaacetic acid (Gd-DTPA), dimeglumine, and Gd-bismorpholide, and two iodinated contrast agents, diatrizoate meglumine and iohexol, were incubated with histamine-containing canine mastocytoma cells. Release of histamine into the supernatant was determined at various contrast-medium concentrations after incubation at 37 degrees C for 30 minutes. RESULTS. Iodinated and Gd-based contrast agents caused release of histamine from mastocytoma cells at similar concentrations (50-150 mM). Mannitol, an osmotic stimulus, caused release of histamine only at concentrations greater than 1,000 mM. CONCLUSIONS. Histamine release from canine mastocytoma cells does not appear to be solely due to osmotic effects, but results from direct stimulation by contrast media. For all agents examined, the concentration at which in vitro histamine release occurs far exceeds the serum contrast media concentration expected in routine clinical application. Direct release of histamine from mast cells does not completely explain the pathogenesis of idiosyncratic anaphylactoid responses to contrast media
— id: 42765, year: 1993, vol: 28, page: 308, stat: Journal Article,

AUR Memorial Award 1991. Immunogenicity of gadolinium-based contrast agents for magnetic resonance imaging. Induction and characterization of antibodies in animals
Baxter AB; Melnikoff S; Stites DP; Brasch RC
1991 Dec;26(12):1035-1040, Investigative radiology
To evaluate the immunogenic potential of gadolinium-based magnetic resonance imaging (MRI) contrast agents, Sprague-Dawley rats were sensitized with gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) dimeglumine and with Gd-DTPA covalently linked to either human serum albumin, dextran, or polylysine. IgG antibodies directed against Gd-DTPA were detected in immune sera by an enzyme-linked immunosorbent assay (ELISA), and were confirmed by competitive inhibition of antibody binding using free Gd-DTPA dimeglumine. Antiserum induced by immunization with human serum albumin-(Gd-DTPA) was characterized by a monophasic competition curve with 50% inhibition (IC50) = 5.5 x 10(-4) M when Gd-DTPA dimeglumine was used as both the well-coating and the displacing agent in a competition ELISA. Antiserum induced by Gd-DTPA dimeglumine alone was characterized by a biphasic competition curve with IC50 = 6.5 x 10(-7) M and 7.9 x 10(-4) M. Antisera obtained after exposure to either dextran-(Gd-DTPA) or polylysine-(Gd-DTPA) were of insufficient titer for characterization. The detection of antibodies specific for Gd-DTPA suggests in vivo protein binding with formation of hapten-carrier conjugates. This hypothesis is supported by increased relaxivity values observed when Gd-DTPA dimeglumine is incubated in serum rather than in water. Gd-DTPA dimeglumine and albumin-(Gd-DTPA) are immunogenic in rats under idealized experimental conditions. Additional studies will be necessary to determine the potential for immunologic response in humans to gadolinium chelates under conditions of exposure inherent in clinical use
— id: 42766, year: 1991, vol: 26, page: 1035, stat: Journal Article,

Linkage analysis of von Recklinghausen neurofibromatosis to DNA markers on chromosome 17
Diehl SR; Boehnke M; Erickson RP; Baxter AB; Bruce MA; Lieberman JL; Platt DJ; Ploughman LM; Seiler KA; Sweet AM; et al.
1987 Dec;1(4):361-363, Genomics
Several recent studies indicate that the von Recklinghausen neurofibromatosis (NF1) gene is located near the centromere of chromosome 17 in some families. However, variable expressivity and a very high mutation rate suggest that defects at several different loci could result in phenotypes categorized as NF1. In order to assess this possibility and to map the NF1 gene more precisely, we have used two polymorphic DNA markers from chromosome 17 to screen several pedigrees for linkage to NF1. We ascertained a large Caucasian pedigree (33 individuals sampled, 17 NF1 affected) as well as eight smaller pedigrees and nuclear families (50 individuals sampled, 30 NF1 affected). Here, we report strong evidence of linkage of NF1 to the centromeric marker D17Z1 (maximum lod = 4.42) and a weaker suggestion of linkage to the ERBA1 oncogene (maximum lod = 0.57), both at a recombination fraction of zero. Since obligate cross-overs with NF1 were not observed for either marker in any of the informative families tested, the possibility of NF1 locus heterogeneity is not supported
— id: 42767, year: 1987, vol: 1, page: 361, stat: Journal Article,