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Biomedical subjects

H L Berman

Publications and source records attributed to H L Berman.

18 recordsLinked to original sources
PubMed1994

Effect of acute experimental pulmonary arterial occlusion on the deposition and clearance of technetium-99m-DTPA radioaerosols.

UNLABELLED: Canine models of autologous PE and balloon occlusion of the pulmonary vasculature were used to evaluate radioaerosol deposition and to quantify radioaerosol clearance in the immediate postembolic period. METHODS: A total of 28 animals were anesthetized, intubated and studied (central balloon occlusion = 4, peripheral balloon occlusion = 7, autologous PE = 5, various control groups = 12). A gamma camera computer system was used to monitor the distribution and clearance rate of inhaled DTPA radioaerosol. The perfusion defect distribution was determined after the radioaerosol study using 99mTc-MAA. RESULTS: A new radioaerosol deposition defect was seen in 3 of 16 animals in a zone of acute vascular occlusion by a balloon (n = 2) or PE (n = 1). In addition, radioaerosol clearance rates were altered substantially. Peripheral vascular occlusion and PE caused radioaerosol clearance rates to accelerate significantly (control clearance half-time = 33.6 +/- 4.6 min, post-balloon occlusion = 19.0 +/- 8.3 min, post-PE = 12.4 +/_ 3.7 min, both p < 0.05). In only one case did these clearance rate changes create a visible abnormality in the aerosol images. CONCLUSIONS: The pulmonary deposition patterns and clearance rates of 99mTc-DTPA radioaerosol can be altered by acute vascular occlusion or PE. These findings should be considered when interpreting radioaerosol images in patients with suspected PE.

Aerosols↗
PubMed1993

Factors affecting x-ray spectra.

The x-ray spectrum is defined as the energy distribution of the radiation produced in an x-ray exposure. The x-ray spectrum has a major impact on image quality and radiation dose delivered to patients. The authors explored the effects of three key factors on x-ray spectra: generator type, peak tube potential, and filtration. Different generator types are characterized by the amount of ripple in the kilovoltage waveform. Those with high (100%) ripple such as single-phase units produce less penetrating radiation than units with low (4%) ripple such as three-phase, 12-pulse generators. As peak tube potential increases, the half-value layer increases nearly linearly; radiation output increases by approximately the square of the tube potential. Filtration materials with atomic numbers less than 42, such as aluminum, titanium, copper, and niobium, produce similar spectra, with only slight variations in efficiency. Although aluminum has the lowest efficiency, this may be compensated for by increasing milliampere seconds. Filtration in addition to the inherent filtration provided by the tube reduces both skin surface dose and average depth-dose, with the optimal amount being approximately 2-3 mm or less of aluminum-equivalent material.

Filtration↗
PubMed1988

Minimally invasive devascularization for variceal bleeding that could not be controlled with sclerotherapy.

The appropriate therapy for continued bleeding despite sclerotherapy remains controversial. This study evaluates a devascularization procedure performed without the risks of major surgery and general anesthesia. Fifty consecutive patients, each with an endoscopically proven variceal hemorrhage that was uncontrollable with sclerotherapy, were treated with minimally invasive devascularization. The procedure was performed in three stages. First, the portal pressure was sharply reduced by angiographic embolization of the midsplenic artery. Then the esophagogastric variceal network was thrombosed by means of a catheter introduced during laparotomy, which created a portoazygos disconnection. Finally, the left gastric and left gastroepiploic arteries were embolized, which completed devascularization of the proximal stomach. According to the Child classification, 16 patients were in class B and 34 were in class C. All Child's class B patients (16/16) and 71% (24/34) of Child's class C patients survived hospitalization. One-year survival was 94% (15/16) for Child's class B and 62% (21/34) for Child's class C patients. Rebleeding occurred in 63% (25/40) of the discharged patients but caused the death of only seven. In conclusion, the 20% initial hospital mortality for these difficult patients was significantly better than that reported for emergency surgery, and the rate of rebleeding was comparable to that seen with other nonshunting therapies.

Arteries↗