Biomedical subjects
B Garra
Publications and source records attributed to B Garra.
Elastography: ultrasonic estimation and imaging of the elastic properties of tissues.
The basic principles of using sonographic techniques for imaging the elastic properties of tissues are described, with particular emphasis on elastography. After some preliminaries that describe some basic tissue stiffness measurements and some contrast transfer limitations of strain images are presented, four types of elastograms are described, which include axial strain, lateral strain, modulus and Poisson's ratio elastograms. The strain filter formalism and its utility in understanding the noise performance of the elastographic process is then given, as well as its use for various image improvements. After discussing some main classes of elastographic artefacts, the paper concludes with recent results of tissue elastography in vitro and in vivo.
Scrotal-inguinal ultrasonography: a technique for identifying the nonpalpable inguinal testis without laparoscopy.
PURPOSE: Treatment of the patient with a nonpalpable testis is controversial, since a high percent will have an inguinal testis or testicular remnant at exploration. While laparoscopy is an effective modality for localizing the intra-abdominal testis, diagnostic laparoscopy is of limited value for patients with nonpalpable (normal or atrophic) inguinal testes. In an effort to identify preoperatively impalpable inguinal testes, we performed scrotal-inguinal ultrasound. MATERIALS AND METHODS: We evaluated 64 patients (74 nonpalpable testes) in the last 4 years, representing 20% of all those presenting with cryptorchidism. Average patient age was 4.5 years (range 6 months to 17 years). All patients underwent preoperative scrotal-inguinal ultrasound and surgical exploration. Diagnostic laparoscopy was reserved for patients with negative ultrasound and no palpable tissue in the scrotum or groin on a preoperative examination. RESULTS: Scrotal-inguinal ultrasound correctly identified 40 of the 42 inguinal testes (95% sensitivity), 7 of the 21 atrophic inguinal testes (33% sensitivity) and 1 of the 11 intra-abdominal testes (9% sensitivity). Therefore, scrotal-inguinal ultrasound correctly identified an inguinal testis or remnant for 47 of the 74 nonpalpable testes (64%), eliminating the need for diagnostic laparoscopy in those cases. For 26 of 74 nonpalpable testes with negative ultrasound 13 had an associated palpable inguinal or scrotal nubbin of tissue, and inguinal exploration only was performed, resulting in 9 orchiectomies, 2 inguinal orchiopexies and 2, 2-stage orchiopexies. Of the 13 nonpalpable testes without palpable nubbins and negative scrotal-inguinal ultrasound 8 were intra-abdominal and 5 were atrophic inguinal testes. CONCLUSIONS: Scrotal-inguinal ultrasound identifies patients with nonpalpable testes who will maximally benefit from diagnostic laparoscopy. When diagnostic laparoscopy was limited to nonpalpable testes without palpable nubbins and negative scrotal-inguinal ultrasound, only 13 of 74 (18%) required laparoscopy. Inguinal exploration without further diagnostic studies is appropriate for boys with nonpalpable testes and palpable nubbins.
Renal duplex Doppler ultrasound: an adjunct in the evaluation of hydronephrosis in the child.
We used renal duplex Doppler ultrasound to evaluate 28 hydronephrotic pediatric kidneys. A total of 28 normal renal units was used as controls. Renal Doppler ultrasound findings were compared with drainage values obtained with renal scintigraphic diuretic renography, and demonstrated close correlation. In control units significantly different resistive index values were noted between patients 0 to 12 months old and those older than 1 year. The younger group had average resistive indexes of 0.66, while the older group had an average value of 0.57 (p < 0.001). In hydronephrotic kidneys resistive index values were significantly higher (0.83) in renal units with obstructive T1/2 values on diuretic renography compared to those with indeterminate or nonobstructive T1/2 values (0.63) (p < 0.001). Renal Doppler ultrasound correlates closely with diuretic renography in hydronephrotic systems in infants and in older children. Additionally, it provides an early, noninvasive modality of assessing the dilated upper tract in infants and older children. Therefore, renal Doppler ultrasound is a reliable adjunct in identifying obstructed renal units.
CT of the liver: a survey of prevailing methods for administration of contrast material.
The members of the Society of Body Computed Tomography were surveyed to determine the most frequently used method of administering contrast material in CT studies of the liver. The respondents represented CT departments performing liver examinations in 22 institutions. No department relied solely on noncontrast scans. In 12 (54%) of 22 institutions, only contrast-enhanced scans were performed. The preferred dose for enhancement was 150 ml of 60% contrast material. Eight (36%) of the 22 respondents obtained images during the administration of a bolus of contrast material, whereas nine (41%) obtained images during the administration of a sustained drip infusion given after a loading bolus. Follow-up in 1987 revealed that two departments had switched to obtaining images during the administration of a bolus. The availability of CT power injectors and refinements in the rapid-scanning capabilities of CT scanners have increased the popularity of obtaining images of the liver during the administration of a bolus of contrast material. Despite this, in many departments, contrast material is still administered via drip infusion in CT studies of the liver.
Ultrasound appearance of extramedullary hematopoiesis.
Extramedullary hematopoiesis accompanies a wide variety of diseases and is defined as the abnormal production of blood outside the normal confines of the bone marrow. Most of the time, extramedullary hematopoiesis is found as microscopic foci in soft tissues; however, on occasion this process may reach a size that is detectable with ultrasound. Two forms are possible: "paraosseous"--in which the normal medullary tissue of the bone marrow ruptures through the bone to present as a paraosseous soft tissue mass,--and "extraosseous"--in which extramedullary hematopoiesis occurs within soft tissue. These "masses" of hematopoietic tissue can appear almost anywhere in the abdomen and pelvis and can mimic a wide variety of more serious diseases.
Successful management of hepatic abscesses by percutaneous catheter drainage in chronic granulomatous disease.
Chronic granulomatous disease (CGD) is a disorder of polymorphonuclear leukocytes that can cause multiple recurrent hepatic abscesses in 40% of those patients with the disorder. The mortality rate from this complication of CGD is estimated at 27%. Treatment has consisted of extensive surgical debridement and drainage and prolonged antibiotic therapy; however, this approach is accompanied by high morbidity and the frequent need for reoperation. Successful percutaneous drainage of multiple hepatic abscesses in a patient who had previously undergone 10 operative procedures to manage hepatic abscesses is reported. With the development of imaging and percutaneous drainage techniques, as well as the recurrent nature of this problem, percutaneous management should be given consideration in appropriate patients with CGD with hepatic abscesses.
A double-blind evaluation of the use of nebulized metaproterenol and isoproterenol in hospitalized asthmatic children and adolescents.
This study compared two beta-adrenergic agents in the treatment of severe asthma of children and adolescents. Thirty patients admitted to Children's Orthopedic Hospital and Medical Center with acute asthma were treated with either isoproterenol 0.05% (iso) or metaproterenol 0.5% (meta) nebulized in physiologic saline and delivered with O2 in addition to intravenous hydration, aminophylline, and corticosteroids. Vital signs, blood gases, and pulmonary function were monitored frequently. No adverse reactions to the study drugs were encountered. Pulse rates increased similarly after treatments with both drugs. Patients treated with meta had somewhat higher rates than those treated with iso. Diastolic blood pressure decreased significantly from admission in the meta group compared to the iso group. For FVC and FEV1, the meta group had greater percentage increases from admission than the iso group at all times, with the difference being significant (p less than 0.05) at 1 and 12 hr. The same trend occurred for FEF 25%-75%. Though iso seemed to cause greater increases in flow immediately after administrations, these changes were transient compared to improvement caused by meta. Thus, meta seemed to be more effective than iso in reversing bronchospasm as measured by certain pulmonary function parameters.
An unusual anomalous intrahepatic connection between the left portal vein and internal mammary veins.
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