Impact of PhD training on scholarship in a neurosurgical career.

Object: The purpose of this study was to report the prevalence of neurosurgeons with both medical degrees (MDs) and doctorates (PhDs) at top-ranked US academic institutions and to assess whether the additional doctorate education is associated with substantive career involvement in academia as well as greater success in procuring National Institutes of Health (NIH) research funding compared with an MD-only degree.

Methods: The authors reviewed the training of neurosurgeons across the top 10 neurosurgery departments chosen according to academic impact (h index) to examine whether MD-PhD training correlated significantly with career outcomes in academia.

Results: Six hundred thirteen neurosurgery graduates and residents between the years 1990 and 2012 were identified for inclusion in this analysis.

Making the diagnosis of acute appendicitis: do more preoperative CT scans mean fewer negative appendectomies? A 10-year study.

Purpose: To determine the frequency of preoperative computed tomography (CT) in the evaluation of patients suspected of having appendicitis at one institution during the past 10 years and to determine whether changes in CT utilization were associated with changes in the negative appendectomy rate.

Materials And Methods: Institutional review board approval was obtained, and a waiver of informed consent was granted for this HIPAA-compliant study. A surgical database search yielded medical record numbers of 925 patients (526 [ 56.

Contrast material administration protocols for 64-MDCT angiography: altering volume and rate and use of a saline chaser to better match the imaging window--physiologic phantom study.

Objective: The purpose of our study was to evaluate the effect of varying volumes and rates of contrast material, use of a saline chaser, and cardiac output on aortic enhancement characteristics in MDCT angiography (MDCTA) using a physiologic phantom.

Materials And Methods: Volumes of 75, 100, and 125 mL of iopamidol, 370 mg I/mL, were administered at rates of 4, 6, and 8 mL/s. The effect of a saline chaser (50 mL of normal saline, 8 mL/s) was evaluated for each volume and rate combination.

Bidimensional measurements in brain tumors: assessment of interobserver variability.

Objective: Bidimensional tumor measurements indicating a greater than 25% increase in tumor size are generally accepted as indicating tumor progression. We hypothesized that use of digital images and a homogeneous reader population would have lower interobserver variability than in previous studies.

Subjects And Methods: Eight board-certified radiologists measured tumor diameters in three planes in two consecutive MRI examinations of 22 patients with contrast-enhancing high-grade brain tumors.

Effect of automatic tube current modulation on radiation dose and image quality for low tube voltage multidetector row CT angiography: phantom study.

Rationale And Objectives: To evaluate the effect of automatic tube current modulation on radiation dose and image quality for low tube voltage computed tomography (CT) angiography.

Materials And Methods: An anthropomorphic phantom was scanned with a 64-section CT scanner using following tube voltages: 140 kVp (Protocol A), 120 kVp (Protocol B), 100 kVp (Protocol C), and 80 kVp (Protocol D). To achieve similar noise, combined z-axis and xy-axes automatic tube current modulation was applied.

Pediatric MDCT: towards assessing the diagnostic influence of dose reduction on the detection of small lung nodules.

Rationale And Objectives: The purpose of this study was to evaluate the effect of reduced tube current (dose) on lung nodule detection in pediatric multidetector array computed tomography (MDCT).

Materials And Methods: The study included normal clinical chest MDCT images of 13 patients (aged 1-7 years) scanned at tube currents of 70 to 180 mA. Calibrated noise addition software was used to simulate cases as they would have been acquired at 70 mA (the lowest original tube current), 35 mA (50% reduction), and 17.

Hypervascular liver tumors: low tube voltage, high tube current multidetector CT during late hepatic arterial phase for detection--initial clinical experience.

Purpose: To intraindividually compare a low tube voltage (80 kVp), high tube current computed tomographic (CT) technique with a standard CT protocol (140 kVp) in terms of image quality, radiation dose, and detection of malignant hypervascular liver tumors during the late hepatic arterial phase.

Materials And Methods: This prospective single-center HIPAA-compliant study had institutional review board approval, and written informed consent was obtained. Forty-eight patients (31 men, 17 women; age range, 35-77 years) with 60 malignant hypervascular liver tumors (mean diameter, 20.

Digital tomosynthesis of the chest for lung nodule detection: interim sensitivity results from an ongoing NIH-sponsored trial.

The authors report interim clinical results from an ongoing NIH-sponsored trial to evaluate digital chest tomosynthesis for improving detectability of small lung nodules. Twenty-one patients undergoing computed tomography (CT) to follow up lung nodules were consented and enrolled to receive an additional digital PA chest radiograph and digital tomosynthesis exam. Tomosynthesis was performed with a commercial CsI/a-Si flat-panel detector and a custom-built tube mover.

Object detectability at increased ambient lighting conditions.

Under typical dark conditions encountered in diagnostic reading rooms, a reader's pupils will contract and dilate as the visual focus intermittently shifts between the high luminance display and the darker background wall, resulting in increased visual fatigue and the degradation of diagnostic performance. A controlled increase of ambient lighting may, however, reduce the severity of these pupillary adjustments by minimizing the difference between the luminance level to which the eyes adapt while viewing an image (L(adp)) and the luminance level of diffusely reflected light from the area surrounding the display (L(s)). Although ambient lighting in reading rooms has conventionally been kept at a minimum to maintain the perceived contrast of film images, proper Digital Imaging and Communications in Medicine (DICOM) calibration of modern medical-grade liquid crystal displays can compensate for minor lighting increases with very little loss of image contrast.

Effect of echo time pair selection on quantitative analysis for adrenal tumor characterization with in-phase and opposed-phase MR imaging: initial experience.

Purpose: To determine the effect of two pairs of echo times (TEs) for in-phase (IP) and opposed-phase (OP) 3.0-T magnetic resonance (MR) imaging on (a) quantitative analysis prospectively in a phantom study and (b) diagnostic accuracy retrospectively in a clinical study of adrenal tumors, with use of various reference standards in the clinical study.

Materials And Methods: A fat-saline phantom was used to perform IP and OP 3.

Radiologists' agreement when using a 10-point scale to report abdominal radiographic findings of necrotizing enterocolitis in neonates and infants.

Objective: The purpose of this study was to evaluate radiologists' agreement when using a 10-point scale of abnormal findings designed to standardize reporting of abdominal radiographs in neonates or infants with suspected necrotizing enterocolitis.

Materials And Methods: A 10-point scale of radiographic findings was devised at our institution and was in use for approximately 18 months before the initiation of this study. After institutional review board approval, 88 abdominal radiographs (anteroposterior and cross-table lateral) were randomly selected for review, allowing for an equal distribution of examinations throughout the scale according to the original examination report.

A comparative contrast-detail study of five medical displays.

The objective of this study was to compare the contrast-detail performance of five different commercial liquid crystal displays (LCDs) to other LCD and cathode-ray tube (CRT) displays for medical applications. A contrast-detail phantom, supplemented with 5 in. of acrylic, was imaged on a commercial digital radiographic system using techniques comparable to chest radiography.

Hippocampal MRI signal hyperintensity after febrile status epilepticus is predictive of subsequent mesial temporal sclerosis.

Objective: The objective of our study was to test the hypothesis that the finding of hyperintense hippocampal signal intensity on T2-weighted MR images soon after febrile status epilepticus is associated with subsequent hippocampal volume loss and persistent abnormal signal intensity on T2-weighted images (i.e., mesial temporal sclerosis).

Effect of varying injection rates of a saline chaser on aortic enhancement in CT angiography: phantom study.

The effect of varying injection rates of a saline chaser on aortic enhancement in computed tomography (CT) angiography was determined. Single-level, dynamic CT images of a physiological flow phantom were acquired between 0 and 50 s after initiation of contrast medium injection. Four injection protocols were applied with identical contrast medium administration (150 ml injected at 5 ml/s).

Central veins of the chest: evaluation with time-resolved MR angiography.

Purpose: To retrospectively assess the diagnostic performance of time-resolved magnetic resonance (MR) angiography in the detection of stenoses and occlusions in the central veins of the chest, with angiographic and surgical findings and consensus readings serving as the reference standard.

Materials And Methods: Institutional review board approval was obtained, and the informed consent requirement was waived for this HIPAA-compliant study. Retrospective analysis was performed with 27 consecutive patients (12 male, 15 female; age range, 16-67 years) who underwent MR venography of the central veins.

Effect of patient size on radiation dose for abdominal MDCT with automatic tube current modulation: phantom study.

Objective: The purpose of this study was to evaluate in a phantom study the effect of patient size on radiation dose for abdominal MDCT with automatic tube current modulation.

Materials And Methods: One or two 4-cm-thick circumferential layers of fat-equivalent material were added to the abdomen of an anthropomorphic phantom to simulate patients of three sizes: small (cross-sectional dimensions, 18 x 22 cm), average size (26 x 30 cm), and oversize (34 x 38 cm). Imaging was performed with a 64-MDCT scanner with combined z-axis and xy-axis tube current modulation according to two protocols: protocol A had a noise index of 12.

Hypervascular liver tumors: low tube voltage, high tube current multi-detector row CT for enhanced detection--phantom study.

Purpose: To prospectively evaluate, for the depiction of simulated hypervascular liver lesions in a phantom, the effect of a low tube voltage, high tube current computed tomographic (CT) technique on image noise, contrast-to-noise ratio (CNR), lesion conspicuity, and radiation dose.

Materials And Methods: A custom liver phantom containing 16 cylindric cavities (four cavities each of 3, 5, 8, and 15 mm in diameter) filled with various iodinated solutions to simulate hypervascular liver lesions was scanned with a 64-section multi-detector row CT scanner at 140, 120, 100, and 80 kVp, with corresponding tube current-time product settings at 225, 275, 420, and 675 mAs, respectively. The CNRs for six simulated lesions filled with different iodinated solutions were calculated.

A novel paradigm for assessing efficacies of potential antidotes against neurotoxins in mice.

Historically, antidotal potencies of cyanide antagonists were measured as increases in the experimental LD(50) for cyanide elicited by the antidotes. This required the use of high doses of cyanide following pre-treatment with the putative antidote. Since IACUC guidelines at our institutions strongly discourage LD(50) determinations: we developed a new test paradigm that allowed for maximal survival of cyanide-treated animals with greatly reduced numbers of animals.

Does image quality matter? Impact of resolution and noise on mammographic task performance.

The purpose of this study was to examine the effects of different resolution and noise levels on task performance in digital mammography. This study created an image set with images at three different resolution levels, corresponding to three digital display devices, and three different noise levels, with noise magnitudes similar to full clinical dose, half clinical dose, and quarter clinical dose. The images were read by five experienced breast imaging radiologists.

Considerations for determining optimal mouse caging density.

At the 2006 National Meeting of the American Association of Laboratory Animal Science, a panel discussed the question of what constitutes optimal or acceptable housing density for mice. Though there is a consensus that present guidelines are somewhat arbitrarily defined, scientific research has not yet been able to provide clear recommendations for amending them. Speakers explored the many factors that influence decisions on mouse housing, including regulatory requirements, scientific data and their interpretation, financial considerations and ethical concerns.

Effect of dose reduction on the detection of mammographic lesions: a mathematical observer model analysis.

The effect of reduction in dose levels normally used in mammographic screening procedures on the detection of breast lesions were analyzed. Four types of breast lesions were simulated and inserted into clinically-acquired digital mammograms. Dose reduction by 50% and 75% of the original clinically-relevant exposure levels were simulated by adding corresponding simulated noise into the original mammograms.

Diffusion tensor imaging assessment of brain white matter maturation during the first postnatal year.

Objective: The purpose of this study was to use diffusion-weighted and diffusion tensor imaging to investigate the status of cerebral white matter (WM) at term gestation and the rate of WM maturation throughout the first year of life in healthy infants.

Materials And Methods: Fifty-three children (35 boys) ranging in age from 1.5 weeks premature to 51.

Assessment of the optimal temporal window for intravenous CT cholangiography.

The optimal temporal window of intravenous (IV) computed tomography (CT) cholangiography was prospectively determined. Fifteen volunteers (eight women, seven men; mean age, 38 years) underwent dynamic CT cholangiography. Two unenhanced images were acquired at the porta hepatis.

Magnetic resonance (MR) cholangiography: quantitative and qualitative comparison of 3.0 Tesla with 1.5 Tesla.

Objectives: To determine quantitative and qualitative image quality in patients undergoing magnetic resonance (MR) cholangiography at 3.0 Tesla (T) compared with 1.5 T.