Structural epicardial disease and microvascular function are determinants of an abnormal longitudinal myocardial blood flow difference in cardiovascular risk individuals as determined with PET/CT.

Background: The aim of this study was to determine whether epicardial structural disease may affect the manifestation of a longitudinal decrease in myocardial blood flow (MBF) or MBF difference during hyperemia in cardiovascular risk individuals, and its dependency on the flow increase.

Methods And Results: In 54 cardiovascular risk individuals (at risk) and in 26 healthy controls, MBF was measured with (13)N-ammonia and PET/CT in mL/g/min at rest and during dipyridamole stimulation. Computed tomography coronary angiography (CTA) was performed using a 64-slice CT of a PET/CT system.

Frequency and magnetic resonance imaging patterns of tuberculous spondylitis lesions in adults.

Objective: To find out the frequency and patterns of various lesions in tuberculous spondylitis in adults on magnetic resonance imaging (MRI).

Study Design: Case series.

Place And Duration Of Study: Radiology Department, Military Hospital (MH) Rawalpindi, from September 2006 to March 2007.

Coronary calcium score scan-based attenuation correction in cardiovascular PET imaging.

Objective: Cardiac positron emission tomography (PET)/CT imaging is a noninvasive procedure allowing the assessment of coronary artery disease (CAD). CT-based attenuation correction of PET data is essential for accurate quantitative analysis in PET/CT imaging. Coronary artery calcium scoring CT (CaScCT) is used as a noninvasive tool for the diagnosis of atherosclerosis in patients with medium risk for CAD.

Mesenchymal stem cells: new approaches for the treatment of neurological diseases.

Cellular therapies represent a new frontier in the treatment of neurological disease. Mesenchymal stem cells (MSCs), which can be harvested from bone marrow, adipose tissue, and umbilical cord blood, among many other sources, possess several qualities which may be used to treat diseases of the central nervous system. MSCs migrate to sites of malignancy, a property which may be used for the treatment of brain cancer.

Harvey Cushing's contributions to motor mapping: 1902-1912.

This review examined Dr. Harvey Cushing's cases in the surgical records of Johns Hopkins Hospital, from 1896 to 1912. 41 patients who underwent cortical stimulation for intra-operative motor mapping were selected for further analysis.

A new technique for intraoperative reduction of occipitocervical instability.

Background: Occipitocervical instability with vertical migration of the odontoid is a rare but potentially debilitating anomaly of the craniocervical junction. Anterior decompression by means of a transoral or transcervical approach followed by posterior instrumentation commonly is used to treat this pathology.

Objective: To develop an innovative operative technique to correct reducible occipitocervical instability using a purely posterior approach.

The Oncogenic Potential of Mesenchymal Stem Cells in the Treatment of Cancer: Directions for Future Research.

Mesenchymal stem cells (MSCs) represent a promising new approach to the treatment of several diseases that are associated with dismal outcomes. These include myocardial damage, graft versus host disease, and possibly cancer. Although the potential therapeutic aspects of MSCs continue to be well-researched, the possible hazards of MSCs, and in particular their oncogenic capacity are poorly understood.

Harvey Cushing's use of a transplanted human vein to treat hydrocephalus in an infant in the early 1900s. Historical vignette.

A review of the Johns Hopkins Hospital surgical records from 1896 to 1912 revealed a case from 1908 wherein Dr. Harvey Cushing attempted to treat hydrocephalus in a 4-month-old infant by constructing a shunt for which he used a venous segment harvested from the patient's father. Prior to this procedure, surgeons used shunts constructed from various often highly immunogenic materials.

Comparative assessment of energy-mapping approaches in CT-based attenuation correction for PET.

Introduction: Reliable quantification in positron emission tomography (PET) requires accurate attenuation correction of emission data, which in turn entails accurate determination of the attenuation map (µ-map) of the object under study. One of the main steps involved in CT-based attenuation correction (CTAC) is energy-mapping, or the conversion of linear attenuation coefficients (µ) calculated at the effective CT energy to those corresponding to 511 keV.

Materials And Methods: The aim of this study is to compare different energy-mapping techniques including scaling, segmentation, the hybrid method, the bilinear calibration curve technique and the dual-energy approach to generate the µ-maps required for attenuation correction.

A novel fuzzy C-means algorithm for unsupervised heterogeneous tumor quantification in PET.

Purpose: Accurate and robust image segmentation was identified as one of the most challenging issues facing PET quantification in oncological imaging. This difficulty is compounded by the low spatial resolution and high noise characteristics of PET images. The fuzzy C-means (FCM) clustering algorithm was largely used in various medical image segmentation approaches.

Image-guided, endoscopic, transcervical resection of cervical chordoma.

Chordomas are rare tumors that arise from the sacrum, spine, and skull base. Surgical management of these tumors can be difficult, given their locally destructive behavior and predilection for growing near delicate and critical structures. En bloc resection with negative margins can be difficult to perform without damaging adjacent structures and causing significant clinical morbidity.

Structure-Function-Based Quantitative Brain Image Analysis.

Many neurodegenerative dementias produce significant alterations in the brain that are often not detectable by neurologic tests or with structural imaging. PET is ideally suited for monitoring cell/molecular events early in the course of a disease as well as during pharmacologic therapy. During the past 2 decades, molecular neuroimaging using PET and magnetic resonance (MR) has advanced elegantly and steadily gained importance in the clinical and research arenas.

Measurement of scattered radiation in a volumetric 64-slice CT scanner using three experimental techniques.

Compton scatter poses a significant threat to volumetric x-ray computed tomography, bringing cupping and streak artefacts thus impacting qualitative and quantitative imaging procedures. To perform appropriate scatter compensation, it is necessary to estimate the magnitude and spatial distribution of x-ray scatter. The aim of this study is to compare three experimental methods for measurement of the scattered radiation profile in a 64-slice CT scanner.

PET-guided delineation of radiation therapy treatment volumes: a survey of image segmentation techniques.

Historically, anatomical CT and MR images were used to delineate the gross tumour volumes (GTVs) for radiotherapy treatment planning. The capabilities offered by modern radiation therapy units and the widespread availability of combined PET/CT scanners stimulated the development of biological PET imaging-guided radiation therapy treatment planning with the aim to produce highly conformal radiation dose distribution to the tumour. One of the most difficult issues facing PET-based treatment planning is the accurate delineation of target regions from typical blurred and noisy functional images.

Disparities in access to neuro-oncologic care in the United States.

Hypothesis: Race/ethnicity and social status influence admission to high-volume hospitals among patients who undergo craniotomy for tumor biopsy or resection.

Design: Retrospective analysis of the Nationwide Inpatient Sample (1988-2005), with additional factors from the Area Resource File.

Setting: A 20% representative sample of all hospitals in 37 US states.

Quantifying the effect of anode surface roughness on diagnostic x-ray spectra using Monte Carlo simulation.

Purpose: The accurate prediction of x-ray spectra under typical conditions encountered in clinical x-ray examination procedures and the assessment of factors influencing them has been a longstanding goal of the diagnostic radiology and medical physics communities. In this work, the influence of anode surface roughness on diagnostic x-ray spectra is evaluated using MCNP4C-based Monte Carlo simulations.

Methods: An image-based modeling method was used to create realistic models from surface-cracked anodes.

Advances in multimodality molecular imaging.

Multimodality molecular imaging using high resolution positron emission tomography (PET) combined with other modalities is now playing a pivotal role in basic and clinical research. The introduction of combined PET/CT systems in clinical setting has revolutionized the practice of diagnostic imaging. The complementarity between the intrinsically aligned anatomic (CT) and functional or metabolic (PET) information provided in a "one-stop shop" and the possibility to use CT images for attenuation correction of the PET data has been the driving force behind the success of this technology.

Hospital costs associated with shunt infections in patients receiving antibiotic-impregnated shunt catheters versus standard shunt catheters.

Background: The average hospital cost for shunt infection treatment is $50,000, making it the most financially costly implant-related infection in the United States. We set out to determine whether introduction of antibiotic-impregnated shunts (AISs) in our practice has decreased the incidence of shunt infection or decreased infection-related hospital costs at our institution.

Methods: Clinical and hospital billing records of pediatric patients undergoing cerebrospinal fluid (CSF) shunt insertion at a single institution from April 2001 to December 2006 were retrospectively reviewed.

A new method for experimental characterisation of scattered radiation in 64-slice CT scanner.

Purpose: The consummate 64-slice CT scanner that spawns a new generation of non-invasive diagnostic tool, however revolutionary, brings with it the incidental by-product that is scattered radiation. The extended detector aperture capability in the 64-slcie CT scanner allows the effects of scattered radiation to be more pronounced and therefore demands that the magnitude and spatial distribution of scatter component be addressed during the imaging process. To this end, corrective algorithms need to be formulated on a basis of a precise understanding of scatter distribution.

Harvey Cushing's attempt at the first human pituitary transplantation.

Background: This case study illustrates Harvey Cushing's pioneering work in pituitary transplantation in the early 20th century and the essential relationship between laboratory research and clinical practice. In 1911, a 48 year-old man presented at Johns Hopkins Hospital with bitemporal hemianopsia, hypothermia, hypersomnolence, decreased libido, polydypsia and polyuria.

Investigation: A review of the Johns Hopkins Hospital surgical records from 1896-1912 on a patient with hypopituitarism secondary to a suprasellar mass, in whom the first documented pituitary gland transplantation was performed.

The clinical role of fusion imaging using PET, CT, and MR imaging.

Multimodality image registration and fusion have a key role in routine diagnosis, staging, restaging, and the assessment of response to treatment, surgery, and radiotherapy planning of malignant disease. The complementarity between anatomic (CT and MR imaging) and molecular (SPECT and PET) imaging modalities is well established and the role of fusion imaging widely recognized as a central piece of the general tree of clinical decision making. Moreover, dual modality imaging technologies including SPECT/CT, PET/CT, and, in the future, PET/MR imaging, now represent the leading component of contemporary health care institutions.

Variations in referral patterns for hypophysectomies among pediatric patients with sellar and parasellar tumors.

Purpose: It has been shown that patients admitted to high-volume hospitals for resection of sellar and parasellar lesions experience reduced mortality and morbidity. It remains unknown what preoperative factors influence admission to high-volume centers. We report a nationwide analysis of patients <18 years of age undergoing neurosurgical intervention for these lesions.

Turbulence model choice for the calculation of drag forces when using the CFD method.

The aim of this work is to specify which model of turbulence is the most adapted in order to predict the drag forces that a swimmer encounters during his movement in the fluid environment. For this, a Computational Fluid Dynamics (CFD) analysis has been undertaken with a commercial CFD code (Fluent). The problem was modelled as 3D and in steady hydrodynamic state.

A virtual sinogram method to reduce dental metallic implant artefacts in computed tomography-based attenuation correction for PET.

Objective: Attenuation correction of PET data requires accurate determination of the attenuation map (mumap), which represents the spatial distribution of linear attenuation coefficients of different tissues at 511 keV. The presence of high-density metallic dental filling material in head and neck X-ray computed tomography (CT) scanning is known to generate streak artefacts in the resulting CT images and thus in the corresponding mumaps generated using CT-based attenuation correction. Consequently, an under/overestimation of activity concentration occurs in corresponding regions of the corrected PET images.