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A R Benedetto

Publications and source records attributed to A R Benedetto.

At least 19 recordsLinked to original sources
PubMed1994

The lag phase of gastric emptying: clinical, mathematical and in vitro studies.

UNLABELLED: The lag phase of gastric emptying reflects, in large measure, the clinically important milling function of the stomach, but there is little agreement on the best way to acquire, analyze and characterize lag phase data of gastric emptying studies. METHODS: Twenty normal volunteers were fed a standard 99mTc-sulfur colloid scrambled egg and toast breakfast and imaging data were acquired at 15-min intervals in both anterior and posterior projections with the subject seated. RESULTS: In a significant percentage of the subjects, the stomach count rate rose above the initial count rate, even with geometric mean correction. We attributed the count rate rise to meal self-absorption and conducted mathematical and in vitro experiments, the results of which supported this thesis. Attempts at modeling the data with power exponential fits were unsuccessful in many cases and were complex, nonintuitive and of limited clinical utility. Accordingly, gastric emptying rates were determined by simple linear regression from geometric mean data. The starting index (the time at which the regression line equalled 100%) was calculated to reflect the lag phase. Normal ranges were determined for men and women. CONCLUSION: Our method of test performance is simple, eliminates confounding variables and provides results with intuitive meaning and with direct clinical relevance.

Adult↗
PubMed1989

Population exposure from nuclear medicine procedures: measurement data.

In order to estimate the public radiation burden from nuclear medicine studies, a TLD chip in a sealed plastic bag was taped on the abdomen of patients who received 111In as chloride or oxine, 201T1 chloride, or one of four common 99mTc agents. The TLD chip was removed after 24 h. Additionally, abdominal skin surface exposure rate measurements were performed with an ionization chamber survey meter at various times (0 to about 60 h). There was superb correlation between TLD and integrated exposure rate measurements and between TLD and ionization chamber measurements and MIRD calculated doses. Scenarios postulated for exposure of co-workers and family members yielded doses between 7 muSv (0.7 mrem) and 20 muSv (2 mrem) for the selected radiopharmaceuticals. Calculations of the total population exposure from nuclear medicine procedures indicate the per capita dose (amortized over the entire population) is approximately 0.4 muSv (0.04 mrem), a negligible dose compared to natural background and total medical irradiation.

Body Burden↗
PubMed1988

Regional alterations in long bone produced by internal fixation devices. Part I. 85Sr clearance.

We examined the effect of rigid plate application on the radiostrontium clearance of the intact canine femur at 6 months. We examined each of the component surgical steps. We calculated the clearance both for the whole bone and for each of the five transverse sections of the whole bone. Screw application, but not drilling, increased the clearance in the segment about the screw holes. Plate application produced an increase in the segment beneath the plate as well as around the screws and in the whole bone. These changes are accomplished not only by an absolute increase in clearance to the middle three segments, but by a relative diminution in clearance by the most proximal and distal segments. The histomorphometric changes in long bones following rigid plating may be accompanied by regional increases in bone blood flow.

Animals↗
PubMed1988

Correlation of right and left ventricular ejection fraction and volume measurements.

First-pass radiocardiography and biplane angiocardiography were performed on 13 patients with left-sided regurgitant valvular disease (R+) and 7 patients without regurgitation but with coronary artery disease and/or cardiomyopathy (R-). Right and left ventricular volumes and ejection fractions were calculated and compared. In the R- group, corresponding right and left ventricular volumes and ejection fractions correlated highly with each other (r = 0.86-0.89, p approximately equal to 0.01). Ejection fractions in the R+ group correlated (r = 0.64, p less than 0.05) only because stroke volume correlation was very high (r = 0.93), with end-diastolic and end-systolic volumes showing no significant correlation. Right ventricular ejection fraction (RVEF) decreased significantly with increasing mean pulmonary artery pressure (PAP) in both R- and R+ groups. The correlation of RVEF and LVEF in the R- group appears to be multifactorial in origin, consisting of effects of increased PAP, the mechanical interference of an enlarged left ventricle on the right ventricle, and direct biventricular ischemic effects. In the R+ group, the correlation appears to be due to only increased PAP and its sequelae.

Angiocardiography↗
PubMed1987

First-pass anger camera radiocardiography: biventricular ejection fraction, flow, and volume measurements.

First-pass (FP) right and left ventricular ejection fraction results were compared with equilibrium radiocardiographic (ER) measurements, and FP left ventricular ejection fraction (LVEF) values were compared with biplane contrast angiographic (CA) measurements in 13 patients with and seven patients without regurgitant valvular disease. Regurgitant fractions were calculated from differences between the FP right and left ventricular stroke volumes. Ejection fractions determined by FP were precise (mean CV = 9.6% RVEF, 13.4% LVEF). Mean LVEF by FP and ER were essentially identical, and both were lower than by CA. LVEF(FP) correlated with LVEF by ER and CA (r = 0.88, p less than 0.001). Mean RVEF by both FP and ER were also correlated (r = 0.82, p less than 0.001). There was correlation between FP (corrected) and CA left ventricular stroke (r = 0.77), end-diastolic (r = 0.88), and end-systolic (r = 0.91) volumes, but underestimates were noted when uncorrected flows were used (r = 0.52-0.71). The FP regurgitant fraction measurements separated the patients with regurgitant valvular disease from those without and agreed well with CA grading of regurgitation.

Blood Volume↗
PubMed1986

Intravascular hemolytic transfusion reaction without detectable antibodies: A case report and review of literature.

A case of intravascular hemolytic transfusion reaction without detectable antibodies occurring in a 55-year-old male is reported. Specificity for the C antigen in the Rh system was demonstrated by technetium-99m red cell survival studies. A cell-mediated mechanism of hemolysis was suspected and investigated. Previously reported cases are reviewed and discussed. The entity of intravascular hemolytic transfusion reaction associated with minimal symptoms and no detectable antibodies deserves further investigation.

Antigens, Surface↗
PubMed1986

Positive predictive value of cholescintigraphy in common bile duct obstruction.

Technetium-99m DISIDA imaging was employed in 400 patients to differentiate obstruction of the common bile duct from medical and other surgical causes of hyperbilirubinemia. Sequential anterior images demonstrated variable degrees of liver uptake, yet there was no evidence of intrabiliary or extrabiliary radioactivity for at least 4 hr after injection in 25 patients. Twenty-three patients were surgically documented to have complete obstruction of the common bile duct. One patient had hepatitis, and another had sickle cell crisis without bile duct obstruction. The remaining patients had either partial or no obstruction of the common bile duct. We conclude that the presence of liver uptake without evident biliary excretion by 4 hr on cholescintigraphy is highly sensitive and predictive of total obstruction of the common bile duct.

Adult↗
PubMed1985

Failure of quality control to detect errors in the preparation of technetium-99m disofenin (DISIDA).

Uptake of Tc-99m disofenin is so strongly hepatobiliary that striking appearance of radioactivity in the reticuloendothelial system (RES) is almost certainly caused by improper preparation of the disofenin kit. Four patients who received injections of Tc-99m disofenin demonstrated a pronounced RES biodistribution in addition to the expected hepatobiliary pattern. Since routine quality control testing had not forewarned us of this gross lack of radiochemical purity, Tc-99m disofenin kits were subjected to a variety of insults to elucidate the mechanisms of quality control failure. Assessment of radiochemical purity was conducted using instant thin-layer chromatography (ITLC) and two solvent systems. We concluded that both Tc-99m pertechnetate and Tc-99m sulfur colloid had been injected into the cold disofenin kit. Visual inspections were not reliable for verifying the final radiopharmaceutical product because of dilution of the sulfur colloid by pertechnetate. ITLC testing failed because the assay method being used at that time did not accurately assess the hydrolyzed fraction (colloidal component). Recommendations are made to preclude recurrence of the errors that occurred.

Adult↗
PubMed1985

Measurement of absorbed dose from radionuclide solutions mixed intimately with the FBX dosimeter.

Chemical dosimeters are used widely for accurate measurement of large radiation doses due to external beam irradiation from radionuclide sources and from particle accelerators. Their use for measurement of absorbed doses from radioactive solutions mixed in the dosimeter solution was reported as early as 1952, but the large activities needed to produce suitable absorbance values in the relatively insensitive dosimeters of that time discouraged further work. This manuscript reports the results of an investigation into the suitability of the ferrous sulfate-benzoic acid-xylenol orange (FBX) dosimeter for measurement of small absorbed doses caused by radionuclide solutions mixed with the dosimeter solution. The FBX dosimeter exhibited a linear dose response as a function of activity for two common radiopharmaceuticals, 99mTc sodium pertechnetate and 131I sodium iodide. Conditions under which the FBX dosimeter may be used with radionuclide solutions were studied and were found to be amenable to routine use by laboratories possessing relatively unsophisticated instrumentation. That any radionuclide could be studied using this dosimeter appears likely.

Benzoates↗
PubMed1984

Patterns of intestinal activity with Meckel's scintigraphy.

Three patterns of intestinal activity were noted in a review of 64 patients studied with Tc-99m sodium pertechnetate for suspected Meckel's diverticulum: no bowel activity seen (37.5%), bowel activity visualized after stomach activity (39.1%), and diffuse bowel activity seen simultaneously with stomach activity (23.4%). The latter pattern, which is relatively common, could mask a true Meckel's diverticulum and lead to either a false-negative or indeterminate diagnosis. A series of 10 dogs was also studied to evaluate the effects of fasting and feeding on the intestinal pattern. No definite relationship was observed.

Adolescent↗
PubMed1984

Accurate estimates of absolute left ventricular volumes from equilibrium radionuclide angiographic count data using a simple geometric attenuation correction.

To simplify and clarify the methods of obtaining attenuation-corrected equilibrium radionuclide angiographic estimates of absolute left ventricular volumes, 27 patients who also had biplane contrast cineangiography were evaluated. Background-corrected left ventricular end-diastolic and end-systolic counts were obtained by semiautomated variable and hand-drawn regions of interest and were normalized to cardiac cycles processed, frame rate and blood sample counts. Blood sample counts were acquired on (d degree) and at a distance (d') from the collimator. A simple geometric attenuation correction was performed to obtain absolute left ventricular volume estimates. Using blood sample counts obtained at d degree or d', the attentuation-corrected radionuclide left ventricular end-diastolic volume estimates using both region of interest selection methods correlated with the cineangiographic end-diastolic volumes (r = 0.95 to 0.96). However, both mean radionuclide semiautomated variable left ventricular end-diastolic volumes (179 +/- 100 [+/- 1 standard deviation] and 185 +/- 102 ml, p less than 0.001) were smaller than the average cineangiographic end-diastolic volume (217 +/- 102 ml), and both mean hand-drawn left ventricular end-diastolic volumes (212 +/- 104 and 220 +/- 106 ml) did not differ from the average cineangiographic end-diastolic volume. Using the blood sample counts obtained at d degree or d', the attenuation-corrected radionuclide left ventricular end-systolic volume estimates using both region of interest selection methods correlated with the cineangiographic end-systolic volumes (r = 0.96 to 0.98). Also, using blood sample counts at d degree, the mean radionuclide semiautomated variable left ventricular end-systolic volume (116 +/- 98 ml, p less than 0.05) was less than the average cineangiographic end-systolic volume (128 +/- 98 ml), and the other radionuclide end-systolic volumes did not differ from the average cineangiographic end-systolic volume. Therefore, it is concluded that: 1) a simple geometric attenuation-correction of radionuclide left ventricular end-diastolic and end-systolic count data provides accurate estimates of biplane cineangiographic end-diastolic and end-systolic volumes; and 2) the hand-drawn region of interest selection method, unlike the semiautomated variable method that underestimates end-diastolic and end-systolic volumes, provides more accurate estimates of biplane cineangiographic left ventricular volumes irrespective of the distance blood sample counts are acquired from the collimator.

Adult↗
PubMed1984

Verification of global cerebral ischaemia using scintigraphy.

The induction of global cerebral ischaemia in laboratory animals is difficult to accomplish and has been even more difficult to verify. Most reported verification methods suffer from lack of sensitivity or from being traumatic and highly invasive. We describe a non-traumatic global cerebral ischaemia verification technique which is quantitative, simple, and highly sensitive. Radioactive technetium-99m pertechnetate is injected intravenously during the ischaemic phase of an experiment and the appearance of radioactivity within the animal's head is quantitated using a gamma camera and nuclear medicine computer. Radioactivity levels below the visual perception threshold are readily measured, thus providing a high degree of confidence in assessing the partial or total nature of cerebral ischaemia.

Animals↗
PubMed1984

Radioangiocardiogram monitoring in patients receiving bisantrene.

Due to the tricyclic structural similarity between the anthracyclines and a new anthracene bishydrazone derivative, bisantrene, changes in myocardial function as detected by radionuclide angiography were sought in early phase I-II trials of the drug. Overall, there appear to be no changes in ejection fraction when determined 24 hours postinfusion, or when determined after low cumulative doses of bisantrene.

Anthracenes↗
PubMed1984

Tc-99m red blood cells for the study of rapid hemolytic processes associated with heterologous blood transfusions.

Chromium-51 labeled erythrocytes (Cr-51 RBC) are suitable for the study of hematologic disorders which involve relatively slow destruction of circulating erythrocytes, taking several days to several weeks. However, Cr-51 RBC are not suitable for investigating rapid hemolytic processes which occur within a matter of a few hours due to the variable and unpredictable elution of Cr-51 from the erythrocytes during the first 24 hours or so. Imaging, which could be useful in identifying organ systems involved in the hemolytic process, cannot be performed with Cr-51 RBC because of the high dose commitment caused by the low yield of gamma rays from Cr-51 (2). A method of labeling RBC with Tc-99m, which results in a radiopharmaceutical that combines the excellent dosimetric and imaging qualities of Tc-99m with an extremely stable bond between the Tc-99m and the RBC, is reported. The successful application of this technique in providing red cell support for a cancer patient with an unusual history of intravascular hemolytic transfusion reactions is also reported.

Adenocarcinoma↗
PubMed1984

Estimates of left-ventricular volumes by equilibrium radionuclide angiography: importance of attenuation correction.

To compare the accuracy of attenuated and attenuation-corrected equilibrium radionuclide angiographic (RNA) left ventricular (LV) volume estimates, we studied 23 consecutive patients with biplane contrast cineangiography (CINE). Attenuated RNA end-diastolic (ED) and end-systolic (ES) volumes were calculated from background-corrected ED and ES counts obtained from hand-drawn regions of interest that were normalized to cardiac cycles processed, frame rate, and blood activity. A simple, geometric attenuation correction was performed to obtain attenuation-corrected RNA LV volumes. The attenuated and attenuation-corrected RNA LV EDV estimates correlated with the CINE LV EDVs ; however, the attenuation-corrected RNA LV EDV estimates correlated more closely. Also, the average attenuation-corrected RNA LV EDV did not differ significantly from the mean CINE LV EDV. Attenuated and attenuation-corrected RNA LV ESV estimates also correlated with the CINE LV ESVs , but the attenuation-corrected RNA LV ESV estimates correlated more closely. Also, the average attenuation-corrected RNA LV ESV did not differ significantly from the mean biplane CINE LV ESV.

Adult↗
PubMed1983

A technique for the preparation of Tc-99m red blood cells for evaluation of gastrointestinal hemorrhage.

Tc-99m labeled red blood cell (RBC) preparations are gaining wide acceptance in the diagnosis and localization of gastrointestinal bleeding. A major requirement of the radiopharmaceutical is that the percentage of Tc-99m attached to red cells in the injected dose must be extremely high, since free pertechnetate is secreted into the gastrointestinal tract and may obscure a bleeding site. We have developed a combined in vivo/in vitro labeling procedure which is simple and rapid, and which enables the administration of substantial amounts of RBC-bound Tc-99m and minimizes the amount of unbound technetium present. The technique is readily utilizable in any nuclear medicine clinic and requires no investigative pharmaceuticals.

Child, Preschool↗
PubMed1982

Treatment of medullary carcinoma of the thyroid with I-131.

We present a patient with radioiodine concentration in pulmonary metastases presumably arising from medullary carcinoma of the thyroid. Transient symptomatic improvement occurred after treatment with a large dose of sodium iodide (I-131). Although radioiodine concentration in medullary carcinoma of the thyroid is rare, the findings in this patient and in other recent reports suggest that an attempt should be made to determine whether a medullary carcinoma concentrates radioiodine. If so, I-131 treatment might be beneficial.

Body Burden↗