Biomedical subjects
P B Dean
Publications and source records attributed to P B Dean.
MR imaging of experimental intramuscular hemorrhage at 0.02 T. Contrast enhancement with Gd-DOTA.
Intramuscular hemorrhage was induced by injecting autologous blood into the paraspinal muscle of 8 rabbits. In order to evaluate the time-dependent changes of hemorrhage observed on MRI, the animals were imaged at different stages of blood resolution at 0.02 tesla (T), and control examined with ultrasound using a 7.5 MHz linear transducer. Six inversion recovery sequences (TR = 1,000 ms. TE = 30 ms, and TI = 18, 48, 148, 201, 302, and 398 ms) were used for the in vivo calculation of T1 relaxation times. IR 1,000 (398)/30 imaging was performed before and after the Gd-DOTA administration. The hemorrhage was evident on MR images throughout the study, especially on the T2 weighted (SE 1,000/100) images. MRI showed the healing lesion longer than ultrasound. The T1 relaxation time increased during the time of resolution. Lesions on days 4 to 7 enhanced in intensity after the injection of Gd-DOTA.
The present state of screening for breast cancer.
The results to date are convincing enough to justify recommending large scale mammography screening. The International Union Against Cancer (UICC) Workshop on screening for breast cancer in 1986 concluded that "In countries where breast cancer is common and where the necessary resources are available, screening using mammography alone or mammography plus physical examination is applicable as public health policy." The Swedish government has recommended screening with mammography for all women aged 40-74. This recommendation repeatedly emphasizes the necessity of high-quality examinations interpreted by well-trained radiologists. Screening with mammography is bringing breast cancer patients to therapy at a far earlier stage in the development of the disease. This calls for a re-evaluation of therapeutic methods.
The value of mammography screening in women under age 50 years.
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The frequency of hyperamylasemia after ERCP with diatrizoate and iohexol.
The frequency of hyperamylasemia was examined in 88 consecutive patients undergoing ERCP (endoscopic retrograde cholangio-pancreaticography) using either meglumine diatrizoate at 306 mgI/ml., or iohexol at 240 mgI/ml. There was no difference in the incidence of hyperamylasemia between these two groups of patients, nor did any other factors appear to influence its occurrence. The authors conclude that acute hyperamylasemia after ERCP is a complication of relatively minor importance unlikely to be reduced by the use of low osmolality contrast media.
Baker's cyst and venoscintigraphy.
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Detectability of spherical objects by computed tomography.
A Lucite phantom was constructed with voids cut in long cylinders, short cylinders and spheres in order to quantitate the effect of partial volume averaging on detectability. Typical scans of varying contrast revealed that the long cylinders cinsistently can be detected to a smaller size than either short cylinders or spheres of the same diameter. The authors feel that low contrast detectability must involve the influence of beam profile on partial volume contrast losses for spherical objects.
Finger joint swelling: correlation with age, gender, and manual labor.
A soft tissue immersion radiography technique was used to study changes in 4,648 finger joints of 166 patients free from signs of inflammatory joint disease. An age-specific correlation was found for joint swelling, joint space narrowing, joint margin spurs, and intraarticular loose bodies. The distal interphalangeal joints were more commonly swollen in women, and the proximal interphalangeal and metacarpophalangeal joints more commonly swollen in manual laborers. Both correlations are highly significant (P less than 0.001). The second and third digits showed a definite predilection for joint swelling. Swelling of finger joints is closely correlated with age and degenerative disease, and its occurrence in older patients is associated with degenerative changes. In manual laborers it should not be interpreted as evidence for inflammatory joint disease.
[Clinical pharmacology of radiographic contrast media].
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Interventional radiologic procedures in the investigation of lesions of the breast.
The interventional radiologist who performs mammography does far more than read films; he examines every patient, punctures cysts, and localizes other breast lesions for precise excisional biopsy. With specimen radiography, he can confirm that suspicious lesions are completely removed by the surgeon and that the tissue in question is selected by the pathologist for examination. Pneumocystography can save the patient the unnecessary, disfiguring surgical removal of benign cysts. Those patients requiring biopsy may be scheduled for the procedure at once, and close cooperation with the surgeon greatly reduces the time the patient must wait to find out whether or not she has breast cancer. Thus, the interventional radiologist can improve the accuracy and speed of diagnosis of breast lesions, establish a definitive diagnosis and expedite the therapeutic management of benign cysts, and save the patient much of the anxiety commonly experienced in waiting for diagnostic results. The end result is better care at a lower cost to the patient and to society.
Accuracy of 100 mm x 100 mm mirror optic camera technique as compared to normal chest radiography technique.
Full size and 100 mm x 100 mm mirror optic camera (photofluorographic) chest films of 121 patients were read by a team of four radiologists. Altogether 2781 diagnostic statements were reported, 968 of which were of primary importance, and only these statements were analysed. Error rates with the standard technique varied between 16 and 31% and with the 100 mm x 100 mm technique between 21 and 38%. The difference in error rates between the techniques used was not statistically significant but there were significant differences between the individual radiologists.
Contrast enhancement: diagnostic significance from a statistical viewpoint.
Contrast enhancement attenuation units were calculated from 13 tissues and organs of 20 rats at five different times after bolus 125I-diatrizoate administration. Percent distribution volume of diatrizoate was calculated from these results. The statistical significance of differences in contrast enhancement between each of 72 tissue pairs was determined at each of the five times. A similar treatment of percent distribution volume for 60 tissue pairs was determined. The time elapsed after contrast medium injection appears to be of pivotal importance in contrast enhancement diagnosis. Calculation of percent contrast distribution volume is of potential diagnostic importance, since it reveals contrast medium behavior not evident from a visual perusal of scans. The above methods can be readily adapted to computed tomography scanning.
A hyperimmunoglobulin E syndrome with normal chemotaxis in vitro and defective leukotaxis in vivo.
A 26-yr-old male with a lifelong history of atopic dermatitis and recurrent severe staphylococcal abscesses was found to have hyperimmunoglobulinemia E. Evaluation of both the humoral and cellular aspects of chemotaxis in vitro showed both neutrophils and monocytes to be normal. However, quantitative neutrophil migration in vivo was significantly suppressed using the patient's own serum as the attractant. This defective migration in vivo was partially corrected by serum from normal donors as the attractant and also partially corrected following plasma infusion in this patient. Evaluation of quantitative leukocyte migration in vivo may be most useful in patients suspected of defects of leukocyte mobility.
The influence of concentration and dose upon the extravascular distribution of intra-arterially injected meglumine diatrizoate.
The dose and concentration of an intra-arterially injected contrast medium, when increased approximately fivefold from a slightly hypotonic solution, produced lower tissue distribution volumes and lower extravascular diatrizoate fractions in the rat. A further fivefold increase in dose (to 1 ml/kg) with little change in concentration produced even lower early distribution volumes. Increases of concentration and dose caused a higher percentage of the contrast medium to remain within the vasculature, presumably as a result of extraction of tissue water by the hypertonic medium. Changes in the concentration of the contrast medium affected its distribution volume for a longer time than corresponding changes in the actual dose. The use of the more concentrated contrast media at higher doses should be expected to give better radiologic detail on angiograms.
Fetal uptake of an intravascular radiologic contrast medium.
Trans-placental passage of methylglucamine diatrizoate was studied in 11 human fetuses after intravenous injection to the mother 5 to 49 minutes prior to abortion by hysterotomy. The contrast medium passed the placental barrier and was detected in all fetal tissues measured. No evidence was found of selective uptake by any fetal tissue. The hazards of fetal exposure should be taken into consideration before the administration of intravascular radiographic contrast agents to pregnant women.
Penetration of naproxen and salicylate into inflammatory exudates in the rat.
Acute inflammation was induced in rats by subcutaneous implantation of plastic sponges, and the penetration of salicylate and naproxen into the inflammatory exudate was studied after oral dosing with these compounds. The penetration of intravenously administered 22Na and 125I-albumin was also studied. It was found that salicylate and 22Na penetrated very rapidly, reaching maximum concentration in the exudate within 3 hours of administration. In contrast, naproxen and 125I-albumin penetrated much more slowly, maximum concentrations in the exudates not being reached until 5 hours after administration. The significance of these results and the role of protein binding is discussed.
Intravenous bolus of 125I labeled meglumine diatrizoate. Early extravascular distribution.
A mixture of 125I labeled meglumine diatrizoate and 131I labeled human serum albumin was injected into the femoral vein of 26 anesthetized male rats. Measurements of the activities in cardiac blood and in different tissues of the lower extremity and in the testis were performed at time intervals ranging from 5 s to 5 min after injection. The determination of tissue uptake and distribution volumes of diatrizoate showed widely differing accumulation of contrast medium. Over 50 per cent of the intravenous bolus of diatrizoate was extravascular at 40 s.
Intra-arterial bolus of 125I labeled meglumine diatrizoate. Early extravascular distribution.
A mixture of 125I labeled meglumine diatrizoate and 131I labeled human serum albumin was injected into the lower abdominal aorta of 30 anesthetized, laparotomized male rats. Measurements of the activities in cardiac blood and in different tissues of the hindlimbs and tests were perfomed at six time intervals ranging from 5 seconds to 2 minutes after injection, the determine early uptake and distribution volumes of diatrizoate. Concentrations and distribution volumes were initially much greater than values obtained after intravenous injection, but these differences had considerably decreased or disappeared by 2 minutes.