Biomedical subjects

G H Mostbeck

Publications and source records attributed to G H Mostbeck.

64 records · Page 4Linked to original sources

PubMed1990

Effect of heart rate on Doppler measurements of resistive index in renal arteries.

The effect of heart rate on Doppler measurements of the resistive index (RI) in renal arteries was studied in eight patients by varying paced heart rate to eliminate intrinsic and extrinsic factors influencing renal vascular resistance. A Doppler spectrum was obtained in renal segmental arteries. The RI was calculated at increasing heart rates from 70 to 120 beats per minute. There was a statistically significant decrease in RI with increasing heart rate (heart rate of 70: RI = 0.7 +/- 0.06; heart rate of 120: RI = 0.57 +/- 0.06; P less than .001), while blood pressure and cardiac output remained constant. To overcome this source of variance, the observed RI can be corrected for heart rate by using the following regression equation. For a heart rate of 80 beats per minute, corrected RI = observed RI - 0.0026(80 - observed heart rate). In interpreting the RI in renal allograft examinations, the actual heart rate of a patient must be taken into account. However, the clinical significance of standardizing the RI for heart rate requires further investigation.

Adult↗

PubMed1990

[Duplex sonography: a highly echogenic splenic cyst or splenomegaly?].

A 27-year old woman presented sonographically with a highly echogenic mass in the left upper quadrant of the abdomen measuring 22 cm in diameter, initially interpreted as splenomegaly. Movement of internal echoes by application of pulsed doppler and by postural change of the patient revealed this mass as a cystic lesion with highly echogenic fluid. At surgery, a pseudocyst of the spleen containing detritus and cholesterol crystals was found.

Adult↗

PubMed1989

Hemodynamic significance of the paraumbilical vein in portal hypertension: assessment with duplex US.

Hemodynamic evaluation of portal and umbilical venous flow with duplex ultrasound (US) was performed in 11 patients with cirrhosis of the liver and a large umbilical vein. Two of these patients had hepatofugal flow in the umbilical vein exceeding hepatopetal flow in the portal vein. These two patients had no evidence of esophageal varices and bleeding. The remaining nine patients had esophageal varices. In these patients, the hepatopetal flow in the portal vein exceeded the hepatofugal flow through the umbilical vein. The authors conclude that duplex US may help identify the massive hepatofugal flow through a large umbilical vein that may reduce the likelihood of esophageal varices and variceal bleeding.

Adult↗

PubMed1989

Optimal needle size for renal biopsy: in vitro and in vivo evaluation.

To evaluate the success and complication rates of small (16- and 18- gauge) needles in biopsy of the kidney, the authors performed in vitro biopsy in a cadaveric kidney and in vivo renal biopsy in 141 patients. Best results were obtained with a 16-gauge modified Menghini needle. In vitro, 9.7 +/- 5.7 (mean +/- standard deviation) glomeruli were retrieved, and the average length of tissue cores was 17.8 mm +/- 8.2. In vivo, 10.63 +/- 6.64 intact glomeruli were retrieved, and a definitive histologic diagnosis was achieved in 86% of patients. The frequency of major complications with this needle was 3.5%, and of minor complications, 5.8%. No major complications occurred after biopsy was performed with 18-gauge needles of the same design. However, the retrieval rate of glomeruli with these smaller needles was insufficient. An 18-gauge needle with two cutting edges yielded tissue cores of 11.0 mm +/- 3.5 in length. In vitro, 6.6 +/- 2.3 glomeruli were retrieved; in vivo, 9.92 +/- 6.65. A definitive histologic diagnosis was achieved with this needle in 75% of patients, and rates of 7.1% for major complications and 10.7% for minor complications were encountered.

Adult↗

PubMedDate not supplied

Flow pattern analysis in the abdominal aorta with velocity-encoded cine MR imaging.

The sites of deposition of atherosclerotic plaque on the aortic wall are considered to be influenced by secondary and retrograde flow patterns that cause regions of altered shear stress. To detect secondary flow patterns and areas of retrograde flow in the abdominal aorta, velocity-encoded cine (VEC) magnetic resonance (MR) imaging was performed at five different levels of the abdominal aorta in nine healthy volunteers. Net retrograde flow (expressed as a percentage of antegrade flow) increased from proximal to distal levels and was maximal (13.8% +/- 11.8) just distal to the origin of the renal arteries. An increase in the duration of retrograde flow over the cardiac cycle was observed from proximal to distal levels. Whereas retrograde flow was present at end systole and early diastole in each volunteer at every level, the duration and amount of retrograde flow during diastole showed high interindividual variation. Such differences suggest the possibility of variable vascular geometric risk factors in the population for the development of atherosclerotic plaque. The location of retrograde flow in the abdominal aorta demonstrated in vivo with VEC MR imaging was close to that obtained with in vitro flow visualization studies in models of the abdominal aorta.

Adult↗

PubMedDate not supplied

Comparison of Duplex sonography and color Doppler imaging in renal allograft evaluation: a prospective study.

A prospective study compared the diagnostic capability of quantitative Duplex sonography (DS) and color Doppler imaging (CDI) in 49 consecutive patients with 50 renal allografts. Sixty five DS examinations and 65 CDI examinations were performed by two independent investigators on two different machines on the same day. The resistive index (RI) was calculated and the color flow of renal arteries was observed up to the arcuate arteries. There was good correlation of RI values obtained by DS and CDI at all vascular sites. Thirty one allografts were functioning stably and 19 were in a state of dysfunction, defined by histology (n = 17). Forty allografts presented with a RI less than 0.9 and normal color flow. All five allografts with a pathologic RI greater than or equal to 0.9 showed abnormal color flow (missing flow in arcuate and/or interlobar arteries). Five allografts had a RI less than 0.9 but abnormal color flow, possibly due to atrial fibrillation, hypertension, heart failure or a combination of these. A normal color flow pattern excludes severe vascular compromise to the allograft. In addition, CDI revealed three biopsy-related vascular lesions; two of them had been missed by DS.

Adult↗

PubMedDate not supplied

Right ventricular diastolic filling: evaluation with velocity-encoded cine MRI.

Abnormal flow velocity curves across the tricuspid valve (TV) and in the superior vena cava have been described in patients with abnormal right ventricular (RV) relaxation or restriction and with pericardial diseases by means of Doppler echocardiography. In this study, various imaging planes and strategies of velocity-encoded cine (VEC) MR for measurement of peak E and peak A velocities and the E/A ratio across the TV were evaluated and compared to Doppler measurements in 10 normal volunteers. In addition, VEC-MR velocity measurements were performed in the superior vena cava. Peak E and peak A velocities derived from three-dimensional VEC-MR phase images were slightly higher than velocities derived from two-dimensional VEC images. Higher velocities were measured by VEC-MR in the vertical long-axis plane compared with the horizontal long-axis plane. Excellent correlations (r > 0.89) were found between E/A ratios derived by VEC-MR and Doppler echocardiography. The interobserver variability for VEC-MR measurements was in the range of 2%. The VEC-MR depicted normal superior vena cava velocity curves in every volunteer. These results indicate that VEC-MR may offer a highly reproducible means of assessing abnormal filling properties of the RV.

Adult↗

PubMedDate not supplied

Weil disease: importance of imaging findings for early diagnosis.

Weil disease is a rare and severe outcome of infection with leptospires. We report the radiographic appearance of this disease in a patient with hepatic, renal, and pulmonary involvement. Imaging findings added significantly to an early correct diagnosis and, thus, to immediate and successful therapy in this critically ill patient.

Adult↗

PubMedDate not supplied

Scimitar syndrome: MR assessment of hemodynamic significance.

We report a case of anomalous pulmonary venous drainage into the inferior vena cava (scimitar syndrome) in which the hemodynamic significance was noninvasively assessed by means of velocity-encoded cine MR. Left-to-right shunt was calculated from direct blood flow measurements performed in the ascending aorta, main pulmonary artery, and aberrant pulmonary vein.

Aged↗

PubMedDate not supplied

Overuse edema in the bone marrow of the hand: demonstration with MRI.

In MRI of the skeleton, marrow edema is a frequent finding that can be caused by avascular necrosis, fracture, bone bruises, transient osteoporosis, osteomyelitis, primary tumors, metastases, and altered biomechanical properties. We examined a 29-year-old woman golfer with mild pain and swelling of the proximal phalanx II of the left hand. No signs of a stress fracture were seen on the MR images or plain radiographs. MRI revealed increased signal intensity on T2-weighted images in the metacarpal and proximal phalanx II in the left hand. We concluded that bone marrow edema may be the result of physiologic bone response to stress and may not necessarily correspond with severe trauma. Our case complements recent observations outlining the influence of altered biomechanics as a reason for marrow edema.

Adult↗