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Biomedical subjects

Yair Safriel

Publications and source records attributed to Yair Safriel.

11 recordsLinked to original sources
PubMed2005

West Nile virus infection: MR imaging findings in the nervous system.

BACKGROUND AND PURPOSE: West Nile virus (WNV) infection is an ongoing seasonal epidemic. We correlated the MR imaging findings with the clinical presentations and outcomes of WNV infection. METHODS: We reviewed 14 brain and three spinal MR images: nonenhanced and contrast-enhanced T1-weighted images (T1WIs) and T2-weighted images (T2WIs), nonenhanced fluid-attenuated inversion recovery (FLAIR) images (11 patients) and enhanced FLAIR images (three patients), with diffusion-weighted (DW) images and apparent diffusion coefficient maps. WNV infection was diagnosed by means of enzyme-linked immunosorbent assay with a plaque reduction neutralization test. We also correlated the MR findings with the clinical presentation, course, and outcome to determine their prognostic importance. RESULTS: MR imaging findings included: 1) normal (five patients); 2) DW imaging-only abnormalities in the white matter, corona radiata, and internal capsule (four patients); 3) hyperintensity on FLAIR images and T2WIs in the lobar gray and white matter, cerebellum, basal ganglia, thalamus and internal capsule, pons and midbrain (three patients); 4) meningeal involvement (two patients); and 5) spinal cord, cauda equina, and nerve root involvement (three patients). All patients with finding 1 and all but one with finding 2 recovered completely. Two patients with finding 3 died. Those with finding 4 or 5 had residual neurologic deficits that were severe or moderate to severe, respectively. CONCLUSION: Patients with normal MR images or abnormalities on only DW images had the best prognosis, while those with abnormal signal intensity on T2WI and FLAIR images had the worst outcomes. No definite predilection for any specific area of the brain parenchyma was noted.

Adolescent↗
PubMed2003

Hematuria as an indicator for the presence or absence of urinary calculi.

The purpose of this study was to determine whether the presence of hematuria or its absence can predict the presence or absence of urinary calculi as determined by computed tomography (CT) scan in patients presenting to the ED with acute abdominal colic. We reviewed the urine analysis and CT scans of all patients presenting to the ED over a 12-month period with acute colic and a clinical suspicion of urinary calculi. Urine samples were drawn on arrival in the ED before CT scanning. Two hundred seventy-seven patients were included in the study. The prevalence of urinary stones as detected by CT was 57.4%. The positive predictive value, negative predictive value, and accuracy for hematuria as a marker for stone disease was 60.9%, 72.4%, and 62.1%, respectively. A total of 3.24% of patients had some degree of obstruction, all of whom had hematuria. The absence of hematuria is not a reliable exclusion criterion for urinary calculi. The detection of urinary stones without hematuria does not imply obstruction.

Biomarkers↗
PubMed2002

Comparing the interpretations of CT pulmonary angiograms by attending and resident radiologists: can residents identify life-threatening pulmonary emboli in hospitalized patients?

OBJECTIVE: CT pulmonary angiography is now often the first-line investigation for pulmonary emboli. When these studies are performed after hours in teaching hospitals, they are often initially interpreted by trainees. It is of great significance whether the interpretations of trainees and certified radiologists with regard to the presence of pulmonary emboli on CT pulmonary angiograms correspond, because of the morbidity and mortality of both the condition and its treatment. MATERIAL AND METHODS: Twenty-five consecutive CT pulmonary angiograms (CTPAs) of hospitalized patients were viewed at lung and soft tissue windows both on a workstation and on hard copies, at the observers' discretion. Each CTPA was divided into 28 arterial zones based on pulmonary anatomy (including the subsegmental arteries), giving a total of 700 arterial zones, and analyzed retrospectively and independently by two cross-sectional imaging specialists and four residents. Each arterial segment was rated with regard to pulmonary embolus as either high, intermediate, or low probability or not visualized. The kappa (Kappa) test, which tests for interobserver agreement, was used for statistical analysis. RESULTS: At the time of the scan all patients were hospitalized for underlying conditions. Of the 25 patients studied, 9 were referred from the ICU, 7 experienced severe acute shortness of breath and respiratory failure, 5 were post-partum women, 2 had had a recent stroke, 1 patient had antithrombin III deficiency, and 1 had a diagnosis of breast cancer. The incidence of pulmonary emboli was 44%. For the main pulmonary arteries interobserver agreement was good (Kappa=0.61) and for the segmental pulmonary arteries it was fair (Kappa=0.26). For the subsegmental arteries interobserver agreement was poor (Kappa=0.16). The zones where interobserver agreement was greatest (Kappa>0.4) were the left main, left lower lobe, and the right main pulmonary arteries. Interobserver agreement was poorest (Kappa<0.05) in the left interlobar, left lower lobe lateral basal segment, right lower lobe superior segment, and left lower lobe superior segment branches. None of the patients expired due to pulmonary emboli. CONCLUSION: Most life-threatening pulmonary emboli requiring urgent treatment are the more central emboli. This study demonstrates that trainees and certified radiologists can make similar conclusions regarding these central pulmonary emboli in hospitalized patients and that preliminary interpretations by trainees should not therefore adversely affect patient care.

Journal Article↗
PubMedDate not supplied

CT pulmonary angiography in the detection of pulmonary emboli: a meta-analysis of sensitivities and specificities.

OBJECTIVE: To determine the overall sensitivity and specificity for CT pulmonary angiography (CTPA) in the diagnosis of pulmonary emboli (PE) using a meta-analysis of the published literature. MATERIALS AND METHODS: A Medline search was constructed to include all English language publications indexed in the Index Medicus from 1990 to 2000, which included the terms CT, PE and pulmonary angiography. Studies selected were designed principally to compare CTPA in the overall detection of PE as confirmed by an abnormal fluoroscopic pulmonary angiogram or a high probability V:Q scan. Results were corrected for the patient sample size in the respective studies prior to pooling the data. In the absence of an accepted technique for calculating a ROC curve in the meta-analysis of imaging studies, a previously untested theoretical technique was used to obtain a composite ROC curve. RESULTS: Twelve studies of CTPA comprising a total of 1250 patients were analyzed. The overall sensitivity and specificity for CTPA after correction for study size was 74.1% and 89.5% with a range of 57-100% and 68-100%, respectively, for the detection of PE. No trend was detected with respect to the year of publication or sample size. CONCLUSIONS: CTPA has acceptable sensitivity and specificity with a strong ROC curve making it a good first line investigation for PE.

Angiography↗
PubMedDate not supplied

CT signs of urethral injury.

Computed tomography (CT) is the accepted frontline imaging modality for blunt abdominopelvic trauma. However, urethral injuries are traditionally diagnosed with retrograde urethrography. The CT appearances of urethral injuries and the signs associated with posterior urethral injuries are not well described in the literature. CT scans of patients with pelvic fractures and urethrographically proved posterior urethral injuries were evaluated. CT scans of patients with similar pelvic fractures who did not have urethral injuries were also evaluated. The CT findings of elevation of the prostatic apex, extravasation of urinary tract contrast material above the urogenital diaphragm (UGD), and extravasation of urinary tract contrast material below the UGD were specific for type I, II, and III urethral injuries, respectively. If extraperitoneal bladder rupture is present along with periurethral extravasation of contrast material, the possibility of type IV and IVA urethral injuries should be considered. In addition, the CT findings of distortion or obscuration of the UGD fat plane, hematoma of the ischiocavernosus muscle, distortion or obscuration of the prostatic contour, distortion or obscuration of the bulbocavernosus muscle, and hematoma of the obturator internus muscle were more common in patients with pelvic fractures and associated urethral injuries than in patients with uncomplicated pelvic fractures.

Humans↗
PubMedDate not supplied

MR spectroscopy in the diagnosis of cerebral amyloid angiopathy presenting as a brain tumor.

We present two cases of focal, tumefactive, masslike lesions of diffuse cerebral amyloid angiopathy (CAA) that presented as areas of increased signal intensity on long TR sequences without contrast enhancement or restricted diffusion. MR spectroscopy revealed normal metabolite ratios and unremarkable spectra. Pathologic tissue showed CAA and CAA with angitis of the CNS. Tumefactive CAA is a rare condition, and we describe its characteristics at MR spectroscopy and diffusion-weighted imaging.

Aged↗
PubMedDate not supplied

Reference values for long echo time MR spectroscopy in healthy adults.

BACKGROUND AND PURPOSE: There is a lack of information with regard to normal metabolic ratios acquired with MR spectroscopy utilizing a long echo time technique. Our purpose was to measure metabolic ratios in healthy adults to determine whether the metabolites varied across brain regions and by sex. METHODS: Single voxel proton spectra were acquired with an echo time of 135 milliseconds in 10 brain regions of 72 healthy subjects ranging in age from 20 to 44 years. Six gray matter sites in the cerebrum included four cortical areas in the frontal, parietal, temporal, and occipital lobes, and two deep nuclear sites in the basal ganglia and the thalamus. Two subcortical white matter regions were in the parietal and the frontal lobes. Two posterior fossa sites included the pons and the cerebellum. All 10 brain regions were not studied in each subject. For each spectrum, the metabolites n-acetylaspartate (NAA), creatine (Cr), and choline (Ch) were identified and ratios of NAA/Cr and Ch/Cr calculated for each brain region. A multifactorial analysis of variance was performed with the two metabolic ratios as dependent variables and with brain region and sex as independent variables. Post hoc statistical analysis consisted of the Scheffé F statistic for significant difference between pairs of brain regions for both metabolic ratios. RESULTS: There was significant regional variation for both the NAA/Cr ratio (P < .0001) and the Ch/Cr ratio (P < .0001). The NAA/Cr ratio was consistent within cortical gray and white matter but differed between cortical gray (smaller ratio) and white matter (larger ratio). The Ch/Cr ratio was variable in the gray matter, differed between some but not all gray and white matter regions, but was consistent within subcortical white matter regions. There was no difference between men and women for either metabolic ratio. CONCLUSION: There was variation of the NAA/Cr ratio and the Ch/Cr ratio across brain regions, but no sex differences were found. These findings provide the requisite normative values to use single voxel, long-echo-time MR spectroscopy in adult patients with neurologic disorders.

Adult↗