Computer processing of the electrocardiogram during transesophageal atrial pacing-induced stress.
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Algorithms↗
Biomedical subjects
H Jadvar
Publications and source records attributed to H Jadvar.
Evaluation of pancreatic carcinoma with FDG PET.
BACKGROUND: To assess the diagnostic usefulness and clinical impact of positron emission tomography with [F-18]fluorodeoxyglucose (FDG PET) on the management of patients with known or suspected pancreatic carcinoma. METHODS: Attenuation-corrected FDG PET was performed in 20 patients (12 male, eight female) with pancreatic carcinoma at the time of initial diagnosis (n = 7), for tumor surveillance after Whipple surgery (n = 11), and for reevaluation after chemoradiation therapy (n = 2). Visual analysis of PET images were correlated with the results of abdominal computed tomography (CT) and carbohydrate antigen (CA) 19-9 serum tumor marker level that were obtained within 1 month of the PET study. Diagnostic validation was by histology in nine patients and by clinical or radiologic follow-up (5-48 months) in 11 patients. Changes in therapeutic management that were prompted by PET were tabulated. RESULTS: PET was concordant with the findings of abdominal CT in 14 patients (13 true positive, 1 true negative). PET detected clinically unsuspected lung lesions, confirmed subsequently by a chest CT, in one of these 14 patients. PET was discordant with CT in six patients. PET detected tumor recurrence in three patients in this group (15% of total) with nondiagnostic CT findings and elevated CA 19-9 serology. In two of these three patients, chemotherapy with gemcitabine was initiated based on PET localization of disease. Tumor was confirmed in the remaining one of the three patients at autopsy shortly after the PET study. FDG localization in a displaced loop of bowel resulted in an apparent false-positive hepatic lesion in one of six patients in the discordant group. PET underestimated the extent of metastatic disease in the remaining two of six patients due to hyperglycemia. CONCLUSION: In patients with suspected pancreatic carcinoma at the time of initial presentation, PET is complementary to abdominal CT and allows detection of unsuspected distant metastases. In patients with suspected recurrent pancreatic carcinoma, based on elevated or rising CA 19-9 serology, PET can localize the disease when abdominal CT is nondiagnostic as a result of posttherapy anatomic alteration. Imaging evaluation with PET may impact the clinical management of patients with pancreatic carcinoma.
Adult↗
Annular pancreas in adults: imaging features in seven patients.
BACKGROUND: Annular pancreas is a rare congenital abnormality that may be associated with variable degrees of duodenal obstruction. This diagnosis is often overlooked in adult patients who present with symptoms suggestive of duodenal obstruction. Imaging evaluation aids in establishing the diagnosis. We evaluated the imaging findings in seven adult patients with known annular pancreas. METHODS: Seven adult patients with abdominal symptoms had evaluation with one or more of the following imaging studies: upper gastrointestinal (UGI) series, computed tomography (CT), and endoscopic retrograde cholangiopancreatography (ERCP). All patients underwent subsequent laparotomy as a part of routine care. Surgical and imaging findings were correlated in each patient. RESULTS: UGI series is suitable for demonstrating different degrees of duodenal narrowing at the level of pancreatic annulus. Contrast-enhanced abdominal CT is useful in visualizing directly the complete or partial annular pancreatic tissue. ERCP is particularly useful in visualizing the annulus duct coursing around the duodenum. CONCLUSIONS: Imaging plays a pivotal role in the diagnosis of annular pancreas in adult patients avoiding surgery for confirmation with its associated cost and risks.
Adolescent↗
A reusable perfusion supporting tissue-mimicking material for ultrasound hyperthermia phantoms.
A new ultrasonically and thermodynamically tissue-mimicking material is reported. The material is well suited for use in phantoms for testing ultrasound hyperthermia systems or related predictive models. Controlled convective heat transfer effects, mimicking to some extent perfusive heat transfer in tissues, can be instituted in the material with appropriate fluid sources and sinks. The material consists of closely packed agar spheres varying in diameters from 0.3-3.6 mm. The interstitial space between spheres is filled with 10% n-propanol solution. The material has two practical advantages over the solid-gel-type tissue-mimicking materials. The first advantage is that it allows rapid return of a hyperthermia phantom to thermal equilibrium following a heating test by rapid circulation of the perfusion fluid. The second advantage is that the material is in a "liquid" form. It can be easily siphoned in and out of phantom containers of any geometric shape for different purposes without change in its physical properties. Methods for measuring ultrasonic and thermodynamic properties of the material and the results of the measurements are reported. The physical parameters measured are the intensity attenuation and absorption coefficients, the ultrasonic speed, the thermal conductivity, specific-heat capacity and the mass density. Temperature measurements in a hyperthermia phantom made of the material are also reported.
1-Propanol↗
SPECT and PET in the evaluation of coronary artery disease.
Cardiac positron emission tomography (PET) is an accurate method for assessing myocardial perfusion and metabolism in the evaluation of coronary heart disease. PET allows more accurate detection of myocardial ischemia than single photon emission tomography (SPECT). In addition, PET has higher spatial resolution and allows attenuation correction and the quantification of various physiologic parameters. PET with 2-(fluorine-18) fluoro-2-deoxy-D-glucose is considered the standard of reference for predicting improvement in regional or global left ventricular function after revascularization by identifying hibernating viable myocardium that shows diminished perfusion and preserved metabolism. Other less commonly used clinical applications of cardiac PET include assessment of myocardial oxygen consumption and fatty acid metabolism. The use of PET in myocardial imaging is expected to increase in the near future with the regional distribution of positron-emitting radiotracers and the emergence of relatively low-cost PET systems.
Clinical Protocols↗
The pill electrode. New technology as an adjunct to nursing assessment of patient arrhythmias.
The value of esophageal electrocardiography (ECG) in differential diagnosis of complex arrhythmias has been well known for the past half century. However, until recently, the technique was not widely used primarily because of the patient discomfort associated with esophageal placement of nasogastric tubes containing the ECG electrodes. With the advent of the pill electrode and development of appropriate recording methodology, interest in and use of esophageal electrocardiography has increased dramatically. In this article, the authors review the historic development of the pill electrode, recording technique, and current case studies in which the technique of pill electrode esophageal ECG monitoring facilitated differential diagnosis of complex arrhythmias.
Electrocardiography↗