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Dima A Hammoud

Publications and source records attributed to Dima A Hammoud.

6 recordsLinked to original sources
PubMed2005

Imaging glial cell activation with [11C]-R-PK11195 in patients with AIDS.

Glial cell activation occurs in response to brain injury and is present in a wide variety of inflammatory processes including dementia associated with human immunodeficiency virus (HIV). HIV-infected glial cells release cytokines and chemokines that, along with viral neurotoxins, contribute to neuronal damage and apoptosis. The purpose of this study was to determine if glial cell activation in HIV-positive (HIV+) patients could be detected noninvasively, in vivo, using [11C]-R-PK11195 with positron emission tomography (PET). [11C]-R-PK11195 is a selective radioligand for the peripheral benzodiazepine receptor (PBR), and is known to reflect the extent of glial cell activation. A subaim was to determine if nondemented HIV+ patients could be distinguished from those with HIV-associated dementia (HAD) on the basis of [11C]-R-PK11195 binding. Five healthy volunteers and 10 HIV+ patients underwent PET with [11C]-R-PK11195. Time-radioactivity curves (TACs) were generated from dynamic PET images in nine regions of interest (ROIs) drawn on coregistered magnetic resonance imaging (MRI) scans. The average radioactivity was calculated in each ROI and was normalized to the average radioactivity in white matter. Patients with HAD showed significantly higher [11C]-R-PK11195 binding than controls in five out of eight brain regions (P < .05, Mann-Whitney U test). Nondemented HIV+ patients did not show significantly increased binding compared to controls. HIV+ patients overall (demented and nondemented) showed significantly higher radioligand binding than controls in five brain regions (P < 0.05). Patients with HAD did not show significant differences in binding when compared to HIV+ nondemented patients. The findings of this pilot study support a role for glial cell activation in HAD, and that PET with [11C]-R-PK11195 can detect the concomitants of neuronal damage in individuals infected with HIV.

AIDS Dementia Complex↗
PubMed2004

Assessment of the neuroradiology fellowship match: year 3.

BACKGROUND AND PURPOSE: When the fellowship match for trainees entering neuroradiology programs was first proposed in 2001, the program directors in neuroradiology agreed to a 3-year trial utilizing the National Residency Match Program (NRMP) for selecting fellows. A decision as to whether to continue with the neuroradiology fellowship match was to be assessed at the 3-year mark in 2004. METHODS: A Web survey designed through the offices of the ASNR was distributed to neuroradiology fellowship program directors after the results of the most recent fellowship match were tabulated in June 2003. The questionnaire included items about the current sentiment about the fellowship selection process. RESULTS: Most (52 of 61 = 85%) neuroradiology program directors favored continuing the match system for selecting fellows. Most believed that the match 1) had little impact on their success in recruiting fellows (43 of 62 = 69%), 2) was fairly administered (100%), and 3) was appropriately timed from February to June in the third year of residency (56 of 65 = 86%). The number of candidates entering the neuroradiology match increased from 71 in 2001 to 124 in 2003. CONCLUSION: Support for continuing a match system for selecting fellows remains high (85%) among neuroradiology program directors. The system is considered fair and does not harm many programs. The recruitment of fellows to neuroradiology via the match has increased over the 3 years of its existence.

Fellowships and Scholarships↗
PubMed2003

Defining thresholds for changes in size of simulated T2-hyperintense brain lesions on the basis of qualitative comparisons.

OBJECTIVE: Our purpose was to define thresholds below which trained reviewers cannot detect changes in the size of T2-hyperintense brain lesions. MATERIALS AND METHODS: We generated T2-weighted brain MR images (TR/TE, 4000/80) with simulated hyperintense lesions derived from a real multiple sclerosis plaque. The size of the original multiple sclerosis lesion was varied by scaling up or down the lesion using a bicubic interpolation method. Three hundred seventy-eight composite images, in which two T2-weighted images containing lesions were paired, were presented to three equally trained neuroradiologists to define thresholds below which changes in original lesion size could not be detected. Stepwise logistic regression was used to evaluate the dependency of size thresholds on the original size of the lesion. RESULTS: Thresholds ranged from a 5% to 15% increase in the original lesion diameter. For increases greater than 15%, all three reviewers detected the change in lesion size irrespective of the diameter of the original lesion. There was a dependency of the threshold on the diameter of the original lesion (p = 0.02). CONCLUSION: Using an MR simulator, we can define thresholds below which changes in original lesion size cannot be reliably detected. These results may guide the design of clinical trials that rely on trained reviewers to assess change in lesion burden.

Brain↗
PubMed2003

The surgical bed after BCNU polymer wafer placement for recurrent glioma: serial assessment on CT and MR imaging.

OBJECTIVE: The objective of our study was to describe the CT and MR imaging appearances of the surgical bed in the brains of patients receiving biodegradable polymers impregnated with N, N'1, 3-Bis-(2-chloroethyl)-N-nitrosourea (BCNU) for recurrent glioma and to determine whether patients receiving placebos could be differentiated from those receiving BCNU based on the pattern and growth kinetics of tumor recurrence. MATERIALS AND METHODS: The CT and MR images of 20 patients who underwent surgery for resection of recurrent high-grade gliomas and placement of intratumoral wafers (11 received BCNU polymer wafers, nine received control wafers) were analyzed for wafer appearance, volume of gas in the tumor bed, and volume of enhancement on serial scans. RESULTS: Wafers appeared as linear hyperdense structures on CT and as linear low-signal-intensity structures on MR imaging and caused no significant enhancement. In the BCNU polymer group, gas volume was 4.0 +/- 3.4 cm(3) (mean +/- SD), whereas gas volume was 1.6 +/- 3.0 cm(3) for the placebo group (Mann-Whitney test, p = 0.03). A trend toward linear rather than exponential recurrent tumor growth was identified for the BCNU polymer group but not for the placebo group. CONCLUSION: BCNU polymer wafers have a specific appearance on CT and MR imaging with which radiologists should be familiar: gas in the surgical bed is an expected transient finding, and tumor regrowth in patients receiving BCNU polymer wafers appeared to occur at a slower rate than in those receiving the placebo.

Adult↗
PubMed2002

Diffuse axonal injuries: pathophysiology and imaging.

Diffuse axonal shear injury is a common traumatic brain injury, with significant neurologic and behavioral impact on patients. Radiologic recognition of this entity and understanding of its sequelae can be of utmost importance in the prediction of outcome and planning for rehabilitation. MRI has proven to be the optimal means of detection and characterization of DAI lesions, with GRE and FLAIR sequences being particularly helpful, and more advanced techniques such as MRS show preliminary evidence of some utility in determining outcome.

Brain↗