Eugene W. Caldwell Lecture. Why Caldwell?

Every year for the past 75 years, the American Roentgen Ray Society has honored Eugene W. Caldwell by including the Caldwell Memorial Lecture as one of the features of the society's annual meeting. In this anniversary year--a year that highlights the history of radiology--it is appropriate to look back on Caldwell's career to examine the reasons for the society's decision to honor him, rather than numerous other eminent radiologists who might have been selected in his place. In the first Caldwell lecture in 1920, Walter Alvarez said, "Caldwell was a pioneer, an inventor, a research worker, a versatile, enthusiastic, and lovable man" [1]. Surely, many radiologists who lived during Caldwell's lifetime and who came later--including some living today--can be described in this way. The purpose of this essay is to offer an explanation of why Caldwell was chosen over the others.

Eugene W. Caldwell Lecture. The American Journal of Roentgenology: past, present, and future.

In November 1895, a German physicist named Wilhelm Conrad Roentgen read before the Physico-Medical Society of Würzburg a paper reporting his discovery of a new type of radiation that he called X-rays. Only 11 years later, the American Journal of Roentgenology began to chronicle progress in the new science of roentgenology, and it has continued to fulfill this mission for 89 of the 100 years since Roentgen's discovery. My purpose in this address is to focus attention on the AJR as part of the centennial of the discovery of the X-ray. I wish to pay tribute to the Journal as a vital part of the American Roentgen Ray Society (ARRS), and--most important--to acknowledge it as a priceless archive and a treasured heritage to be passed on to future generations of all radiologists. I will recognize the contributions of the key people in the recent history of the AJR who have made the Journal what it is today, reflect on the changes that have occurred during my tenure as editor, and finally, discuss the challenges that I think the Journal will face in the future. This constitutes my valedictory report--my farewell reflections on the Journal, now that my tenure as editor is ending on July 1, 1995.

Biodistribution of GdCl3 and Gd-DTPA and their influence on proton magnetic relaxation in rat tissues.

The biodistribution and relative molar effectiveness of the ionic (GdCl3) and chelated (Gd-DTPA) forms of gadolinium (Gd) to enhance proton relaxation rates in rat kidney, liver and spleen were evaluated. Rats were given intravenous injections of either GdCl3 (100 mumol/kg) or Gd-DTPA (178 mumol/kg). Gd-DTPA was primarily contained in the vascular compartment and was quickly accumulated in the kidney after injection with a relaxivity of 4.3 sec-1 (mumol/g kidney)-1. It was eliminated quickly from the body with only 2% of the injected dose remaining after 120 min. After GdCl3 injection, Gd was found primarily in liver and spleen. It accumulated continuously reaching 72% of the injected does in these two tissues after 120 min. Despite this continuous increase in tissue Gd concentration, the relaxation rates showed saturation in liver and spleen. The results suggest that after GdCl3 was injected it distributed either in a protein bound form that was effective at causing relaxation or in a colloid form that was not effective. The biodistribution of GdCl3 was such that it was determined by the phagocytic action of the recticuloendothelial system on a colloid. The biodistribution and tissue relaxivity of Gd-DTPA suggest it will be a useful vascular MRI contrast agent. However, the usefulness of GdCl3 as an MRI contrast agent is limited not only by its acute toxicity but also by its saturable effect on tissue relaxation rates. Consequently, GdCl3 has only a modest influence on tissue relaxivity.

Influence of paramagnetic ions and pH on proton NMR relaxation of biologic fluids.

The extent to which various concentrations of the paramagnetic metal ions [gadolinium (III), manganese (II), chromium (III), iron (III), nickel (II), copper (II), and cobalt (II)] affect proton magnetic relaxation times of distilled water, 4% human serum albumin (HSA), and dog plasma was studied in vitro. The pH of water and HSA varied from 4 to 8. Nuclear magnetic resonance relaxation parameters, T1 and T2, were measured at 10.7 MHz using inversion recovery and spin-echo radiofrequency sequences, respectively. The presence of Mn(II), Gd(III) and Cr(III) in water significantly reduced T1, while Fe(III), Ni(II), Cu(II) and Co(II) had only a minimal effect. In 4% HSA and dog plasma Mn(II) and Cu(II) had the greatest effect on T1. At neutral pH, Gd(III) and Cr(III) had little effect on T1, while Mn(II) induced a large shortening of T1. All of the metal ions changed T2 less than T1. These differences in proton relaxation enhancement caused by the various ions in the three solutions studied are due to variations in the effective magnetic moment, the degree of binding of the ions to protein, and the chemical form of the ion associated with changes in pH. Thus, it is impossible to predict the effect of metal ions on proton relaxation in vivo based solely on in vitro studies, because of the complexity of various biologic fluids in vivo.

Influence of Mn(II) on NMR relaxation times of biological fluids.

The extent that various concentrations of the paramagnetic metal ion manganese [Mn(II)] affect nuclear magnetic resonance (NMR) relaxation times was studied in vitro. Serial dilutions of Mn(II) were prepared in distilled water, 4% human serum albumin, dog plasma, dog gallbladder bile, and dog hepatic bile. T1 and T2 of each were measured at 10.7 M Hz using magnetization recovery and spin-echo radiofrequency sequences, respectively. The results show that relaxation rates (1/T1 and 1/T2) increase in a linear manner with increasing concentration of Mn(II) in all of the solutions tested. Mn(II) dissolved in dog gallbladder and hepatic bile, dog plasma, and 4% human serum albumin reduced relaxation times to a greater extent than Mn(II) in water. T1 times were reduced to a greater extent than T2 values. Thus, in T1 weighted magnetic resonance images, the NMR signal used to produce images would be more sensitive to the presence of Mn(II) in these biological fluids than in water. Furthermore, the magnitude of this in vivo effect of Mn(II) on NMR relaxation parameters depends not only on the concentration of this paramagnetic ion, but also on the constituents comprising the biological fluids (intra- and extracellular water, bile, plasma) and the nature of the chemical molecular interactions between these constituents and Mn(II).

Cryptosporidiosis of the stomach and small intestine in patients with AIDS.

Cryptosporidiosis is a parasitic disease of the gastrointestinal tract that causes a choleralike diarrhea in patients with the acquired immunodeficiency syndrome (AIDS). Review of barium studies of the stomach and small intestine in 16 AIDS patients with cryptosporidiosis showed that the studies were abnormal in 13. Of these, five had moderate or marked prominence of the mucosal folds, and eight had slight prominence. The jejunum was predominantly involved in nine; the entire small intestine was uniformly affected in the other four. Three of the 16 patients had moderate or marked dilatation of the small intestine. One had marked dilution of the barium, and one had marked fragmentation and flocculation of the barium. There was narrowing and rigidity of the gastric antrum in two patients. These radiographic findings are nonspecific, but are indicative of cryptosporidiosis in a patient with AIDS and protracted diarrhea.

Radiologic features of multinodular lymphoma of the colon.

The colon is frequently involved in patients with systemic malignant lymphoma and may be the site of initial clinical presentation. Multiple nodules are one of the manifestations of colonic lymphoma. In an effort to determine the most useful and characteristic features, the radiographic findings in 23 patients with multinodular colonic lymphoma were reviewed. The most characteristic radiographic features were identified: (1) variably sized, smooth, sessile nodules with an average diameter of 7 mm; (2) a cecal mass larger than 3 cm; (3) distortion of the haustra ; (4) incomplete evacuation of barium; and (5) involvement of the stomach, small bowel, or spleen. Less common were irregular, pedunculated, or filiform nodules and occasional umbilication . The differential diagnosis includes gastrointestinal polyposis, benign lymphoid hyperplasia, and inflammatory bowel disease. The radiologist may be the first to suggest the correct diagnosis when lymphoma patients present with multiple colonic nodules.

Uptake of iopanoic acid by isolated rat hepatocytes in primary culture.

Uptake of iopanoic acid (IOP) was studied in 3-day primary cultures of rat hepatocytes isolated by the collagenase perfusion method. 125I activity of cells after incubation with 125I-IOP (1.0-100 microM) was used as a measure of uptake. At each IOP concentration uptake was linear for the first 45 s. The initial uptake velocity was directly proportional to IOP concentration and was nonsaturable up to 100 microM. The calculated uptake rate constant was 0.67 nmol . mg prot-1 . min-1 . microM-1. Uptake was only slightly reduced when the incubation was performed at 4 degrees C and was independent of sodium concentration. Albumin in the medium reduced IOP uptake. Uptake, however, was always greater than that predicted from the unbound IOP concentration alone. The data indicate that the hepatocyte uptake of IOP occurs by both a passive process and a saturable process. The saturable uptake component depends on an albumin-IOP-hepatocyte interaction. The influence of albumin on uptake occurs possibly by an undefined specific cell surface phenomenon of albumin that promotes uptake of IOP or by enhancement of the diffusibility of IOP across the unstirred layer.

The hyperplastic cholecystoses: cholesterolosis and adenomyomatosis.

Cholesterolosis and adenomyomatosis, two diseases of the gallbladder that are unrelated to cholelithiasis or cholecystitis, are detected on oral cholecystograms with considerable frequency. These disorders are of uncertain etiology, and it is also unclear if they cause clinical symptoms. Cholesterolosis is the result of the accumulation of triglycerides and esterified sterols in macrophages in the lamina propria. The abnormality is unassociated with cholesterol gallstones, supersaturation of bile with cholesterol, hyperlipidemia, obesity, or atherosclerosis. Adenomyomatosis involves hyperplasia of the tissues of the gallbladder wall with outpouches of the mucosa similar to diverticula of the colon. In this report, the pathology, etiology, clinical and radiologic features, and treatment of these two entities are reviewed.

Cholecystokinin cholecystography, sonography, and scintigraphy: detection of chronic acalculous cholecystitis.

Because the efficacy of cholecystokinin cholecystography in the detection of chronic acalculous cholecystitis remains in doubt, the procedure is rarely used in clinical practice. However, the ability to observe gallbladder contraction with sonography and 99mTc-para-isopropylacetanilido-iminodiacetic acid cholescintigraphy (PIPIDA) offers a possibility to improve the sensitivity of the test. To determine if the degree of gallbladder contraction after cholecystokinin is the same as measured by the three techniques and if it differs in symptomatic patients compared to the normal population, cholecystokinin cholecystography, cholecystokinin sonography, and cholecystokinin PIPIDA were performed in 10 symptomatic patients and 10 normal volunteers. The mean maximum contraction of the gallbladder during the three studies was 63%, 61%, and 68%, respectively, for the volunteers, and 72%, 63%, and 73%, respectively, for the patients. The mean maximum gallbladder contraction during all three procedures was 64% +/- 26% SD in the volunteers and 74% +/- 17% SD in the patients. The differences were not statistically significant. Although there was good correlation in the degree of maximum gallbladder contraction among cholecystokinin cholecystography, cholecystokinin sonography, and cholecystokinin PIPIDA, marked variation in both the volunteers and the patients makes it unlikely that the degree of contraction as observed by any of these techniques can be used to indicate the presence of chronic acalculous cholecystitis.