Biomedical subjects

R Semelka

Publications and source records attributed to R Semelka.

7 recordsLinked to original sources

PubMed1999

A multicenter, randomized, double-blind study to evaluate the safety, tolerability, and efficacy of OptiMARK (gadoversetamide injection) compared with Magnevist (gadopentetate dimeglumine) in patients with liver pathology: results of a Phase III clinical trial.

The purpose of this study was to evaluate the safety and efficacy of OptiMARK (gadoversetamide injection) compared with Magnevist (gadopentetate dimeglumine) in hepatic MRI of patients with suspected liver pathology. A Phase III, multicenter, randomized, double-blind, parallel group study was performed in adults with suspected liver pathology. All patients underwent contrast-enhanced computed tomography within 3 weeks prior to magnetic resonance scanning. Ninety-nine patients received OptiMARK, and 94 patients received Magnevist at a dose of 0.1 mmol/kg. Precontrast T1- and T2-weighted spin-echo imaging and T1-weighted gradient-echo imaging were performed, followed by T1-weighted gradient-echo imaging at 15-20 seconds, 1 minute, and 5 minutes after intravenous contrast injection. Three primary efficacy endpoints (confidence in lesion diagnosis, level of conspicuity, and lesion border delineation) were evaluated on the precontrast image set and compared with the pre plus postcontrast image set. Vital signs, physical examination, electrocardiograms (ECGs), and laboratory parameters (chemistry, hematology, and urinalysis) were measured at various time points. Adverse events were recorded. The study design and statistical analyses were chosen to demonstrate presumed equivalence of OptiMARK and Magnevist. There were no statistically significant differences in efficacy between OptiMARK and Magnevist as assessed by either blinded readers or the on-site principal investigators. No serious or unexpected adverse events were noted. Of the 193 patients receiving contrast media, 82 experienced a total of 154 adverse events. Thirty-three (21.4%) of these 154 adverse events were felt by the on-site investigators to be probably related to either study agent: 15 events in 9 patients in the OptiMARK group, and 18 events in 13 patients in the Magnevist group. Headache was the most common adverse event, occurring in 10.1% of the OptiMARK patients and 12.8% of the Magnevist patients. No clinically relevant trends were observed in any laboratory parameter or ECG findings in either treatment group. The results demonstrate the safety, efficacy, and equivalence of OptiMARK and Magnevist at a dose of 0.1 mmol/kg in hepatic magnetic resonance imaging of patients with suspected liver pathology.

Contrast Media↗

PubMed1998

Diagnosis and monitoring response to treatment of hepatosplenic candidiasis in patients with acute leukemia using magnetic resonance imaging.

Hepatosplenic candidiasis (HSC) is a morbid complication encountered in immunocompromised individuals, especially, those being treated with intensive chemotherapy protocols for acute leukemia. Immediate recognition of this complication and initiation of appropriate treatment is crucial in order to control the infection, decrease the morbidity and mortality, and avoid delays in treatment of the underlying condition. The definitive diagnosis requires either positive blood cultures for yeasts in the presence of abnormal findings on imaging studies consistent with HSC, or liver biopsy demonstrating yeast forms or pseudohyphae. We describe our experience in the evaluation of 15 patients with HSC using magnetic resonance imaging (MRI) as a diagnostic and follow-up tool. The diagnosis of HSC was established by liver biopsy in 11 patients (73%), and by positive blood cultures for Candida in 4 patients (27%). All patients had MRI findings consistent with HSC during the study period. Amphotericin B was administered intravenously to all 15 patients (median duration of treatment, 62 days). Repeat MR images were obtained at 2 weeks, 6 weeks and then at monthly intervals until the resolution of abnormalities. The median time for the disappearance of MRI lesions was 9 weeks. Alterations in the appearance of lesions on MRI were noted throughout chemotherapy in all the 13 (86.6%) responding patients. Our results suggest that MRI when used in patients with high clinical suspicion for HSC provide an alternative for liver biopsy or other invasive diagnostic procedures and that appropriate response to treatment can be safely monitored by obtaining sequential MRI studies.

Adolescent↗

PubMed1997

Littoral cell angioma in a patient with Epstein syndrome.

A 61-year-old male with Epstein syndrome and chronic renal failure was admitted to our institution for kidney transplantation. He was asymptomatic at the time of evaluation. Physical examination revealed pallor and marked splenomegaly measuring approximately 12 x 10 cm below the left costal margin. Because of this finding, and a history of resected non-small lung cancer, a CT scan of the abdomen was obtained. This demonstrated massive, diffusely nodular splenomegaly. This article describes the histopathologic and immunohistochemical findings of littoral cell angioma, a novel splenic tumor. Also, we discuss the differential diagnosis and include a description of the imaging study performed. To our knowledge, this is the first case report of littoral cell angioma occurring in a patient with Epstein syndrome, and the first radiographic appearance of this rare tumor.

Carcinoma, Non-Small-Cell Lung↗

PubMed1991

Right and left ventricular stroke volume measurements with velocity-encoded cine MR imaging: in vitro and in vivo validation.

The accuracy of measurements of flow velocity determined by using cine MR phase velocity mapping--velocity-encoded cine (VEC) MR--was assessed by comparing VEC MR data with independent measurements in a flow phantom and in human subjects. Constant flow velocities generated in a phantom (range, 20-408 cm/sec) were determined correctly by VEC MR (r = .997, standard error of the estimate [SEE] = 7.9 cm/sec). Peak systolic velocities in the main pulmonary artery determined by VEC MR correlated well with the measurements obtained by using continuous-wave Doppler echocardiography (r = .91). Stroke volumes measured at the aorta by VEC MR and continuous-wave Doppler imaging also correlated well with each other (r = .80). VEC MR measurements of aortic and pulmonary flow provided left and right ventricular stroke volumes that correlated well with left ventricular stroke volumes determined by short-axis cine MR images (r = .98, SEE = 3.7 ml, and r = .95, SEE = 4.8 ml, respectively). Intra- and interobserver variabilities were small for both left and right ventricular stroke volumes as measured with VEC MR. These results indicate that VEC MR accurately and reproducibly measures aortic and pulmonary flow velocities and volumes in the physiologic range of humans, and can be used to measure right and left ventricular stroke volumes under normal flow conditions.

Adult↗

PubMed1989

Prosthetic testicle: appearance at MR imaging.

The appearance of testicular prostheses on magnetic resonance (MR) images was studied in six patients with seven silicone implants: two with a fluid consistency and five that were solid. On T1-weighted images, both types of prosthesis demonstrated homogeneous low signal intensity; on T2-weighted images, the fluid implants had a uniformly low signal intensity, and the solid implants had a uniformly high signal intensity. Both prostheses created a chemical shift artifact on all imaging sequences owing to the difference in chemical composition of the prostheses and the surrounding tissue.

Adolescent↗

PubMed1988

Sarcoidosis as a cause of linitis plastica.

We report a patient with gastric sarcoidosis. After initial pulmonary sarcoidosis, which responded to corticosteroids, the patient developed linitis plastica of the stomach which was treated by partial gastrectomy and steroids.

Adenocarcinoma, Scirrhous↗

PubMedDate not supplied

Contrast-enhanced 3D FISP MR angiography of the aortic arch ostia: preliminary results.

PURPOSE: The goal of this work was to evaluate three-dimensional (3D) contrast-enhanced MR angiography (MRA) for the detection of ostial stenoses of the aortic arch. METHOD: Sixteen patients with suspected carotid atherosclerotic disease prospectively underwent digital subtraction angiography of the aortic arch followed by contrast-enhanced MRA using a 3D fast imaging with steady-state precession (FISP) technique (TR = 5 ms, TE = 2 ms, flip angle = 30 degrees). Three neuroradiologists blindly measured stenoses on the catheter angiograms and MRA. Evaluation included the ostia of the innominate, left carotid, and left subclavian arteries. Any significant disagreement on catheter angiography was resolved by consensus. The MRA grades of each of the three observers were then compared with the consensus grades of the contrast angiogram. RESULTS: Forty-eight vessels were scored, of which five had significant stenoses. MRA demonstrated 100% sensitivity, 89% specificity, 52% positive predictive value, and 100% negative predictive value. The Bowker test for symmetry indicated no significant difference between conventional angiography and MRA scores (p = 0.32-0.75), and there was good agreement between the three observers (weighted kappa = 0.75-0.86). CONCLUSION: Contrast-enhanced 3D FISP MRA may be a useful imaging modality for the detection of significant stenoses at the ostia of the major aortic arch branches.

Adult↗