Frank E. Carroll

Observer variation in quantitative assessment of rheumatoid arthritis part II. A simplified scoring system

A new and more comprehensive simplified scoring system to provide quantitative assessment of radiographic findings in rheumatoid arthritis was studied by six observers with different levels of expertise. Since the observers, film set, and joints scored were the same as in a prior study of a more detailed scoring method, a precise comparison of the results was made. Interobserver variation with the simplified scoring system was small; there were highly significant correlations of the total radiographic scores for all observers (R = .898-.978, P less than .001). There were highly significant correlations between scores obtained with the simplified scoring system and those obtained with the more detailed method (R = .920-.955, P less than .001). When the same joints were evaluated by the two methods, a significantly greater number of possible observations could be scored with the simplified scoring system than with the more detailed method (X2 = 131.07, P less than .001). The simplified scoring system required 2.3 times less time to use in the hands of experienced observers.

Near-monochromatic X-ray beams produced by the free electron laser and Compton backscatter

The intense photon output of a free electron laser may be made to collide with its own high energy electron beam to create nearly monochromatic x-rays using Compton backscatter techniques. These x-rays can be used for imaging and non-imaging diagnostic and therapeutic experiments. The initial configuration of the Vanderbilt Medical Free Electron Laser (Sierra Laser Systems, Sunnyvale, CA) produces intense x-rays up to 17.9 keV, although higher energies are easily attainable through the use of frequency doubling methods, alteration of the energy of the electron beam and coupling to conventional laser inputs.

ATTENUATION OF MONOCHROMATIC X-RAYS BY NORMAL AND ABNORMAL BREAST TISSUES

RATIONALE AND OBJECTIVES.A prior study indicated that differences in the x-ray linear attenuation coefficients of cancerous and normal breast tissues tend to increase as the energy of the incident beam decreases. The authors investigated x-ray energies down to 20 keV. In the current study, the linear attenuation coefficients for normal and selected cancerous breast tissues within the energy range of 14 to 18 keV were determined. METHODS.Fifty breast biopsy specimens consisting of a mixture of breast malignancies, normal tissues, fat specimens, and tumors grown in rats were used. X-ray linear attenuation coefficients were measured for each sample within the energy range of 14.15 to 18 keV, using monoenergetic x-rays from beamline X-19A at the National Synchrotron Light Source at Brookhaven National Laboratory. Each sample was measured at 130 different energies starting at 14.15 keV with step sizes of 0.030 keV. Correlation of the measured attenuation coefficients for cellular makeup was performed. RESULTS.The mean of linear attenuation coefficients for samples classified as “cancers” was 10.9% higher than the mean of samples classified as “normal” breast tissues and was 66.5% higher than the mean of samples classified as normal breast fat. CONCLUSIONS.Differences in the linear attenuation coefficients of monochromatic x-rays between 14.15 and 18 keV do exist between normal and cancerous tissues, but there is some degree of overlap.

Tunable, monochromatic X-rays: An enabling technology for molecular/cellular imaging and therapy

Pulsed, tunable, monochromatic X‐rays hold great potential as a cellular and molecular probe. These beams can be tuned to the binding energy of orbital electrons in atoms, making them extremely useful in diagnostic k‐edge imaging and Auger cascade radiotherapy. Their wide tunability makes them ideal for the performance of various techniques as disparate as protein crystallography and three‐dimensional, compressionless, monochromatic mammography. Since only the frequency best suited to the task at hand is used, radiation exposure to patients or animals is exceedingly low when compared to standard X‐ray techniques.

Observer variation in quantitative assessment of rheumatoid arthritis: Part I. Scoring erosions and joint space narrowing

Six observers, including two bone and joint radiologists, two general radiologists, and two senior radiology residents, compared scores to quantitate radiographic findings in the hands and wrists of patients with rheumatoid arthritis. In the scoring system used, erosions and joint-space narrowing are graded separately. This scoring system differs from other methods in that equivocal findings are not scored, while ankylosis, subluxation, and dislocation are scored, and data from postoperative joints are included. Total radiographic scores were highly significantly correlated for all observers (R = .908-.958, P less than .001), as were subtotal scores for erosions (R = .723-.931, P less than .001) and joint-space narrowing (R = 0.843-0.966, P less than .001). Analysis of proximal interphalangeal, metacarpophalangeal, and wrist-joint scores showed highly significant correlations for all observers in each location. Highly significant correlations were found among three separate readings of two bone and joint radiologists (R = .950-.961, P less than .001). This scoring system provides highly consistent and reproducible results, even in the hands of less experienced observers.

MR imaging parameters in the study of lung water. A preliminary study.

The use of magnetic resonance (MR) to evaluate lung water is made difficult by several factors: paucity of proton signal from normal lung, respiratory and cardiac motion, and long relaxation times of lung fluids. To optimize scanning parameters for this use, and to test MRs ability to detect and quantitate regional and temporal variations in signal intensity in hydrostatic pulmonary edema, in vivo experiments were performed with a 0.5 tesla whole body MR imaging device. Human volunteers were studied in prone and supine positions using spin echo technique (TE = 30 msec) with varying TR, and with respiratory and cardiac gating. In addition, sedated, intubated, chronically prepared sheep were paralyzed to control extraneous motion and allow the use of a high frequency ventilator, thereby eliminating respiratory gating. Elevated pulmonary hydrostatic pressure was induced in these sheep by inflation of a left atrial balloon. Relative signal intensity from the lung rises with lengthening TR. Cardiac gating diminishes motion artifact, but masks extravascular water by enhancing signal from slowly flowing blood by an average of 44%. A gravity-dependent gradient of signal intensity predictably shifts in supine and prone positions. The use of longer TRs, respiratory gating, and cardiac gating all proportionally prolong data acquisition times to an objectionable degree. Without the use of gating, a gradual rise in relative signal intensity is seen in the sheep lung following the establishment of elevated hydrostatic pressure in the pulmonary circuit, and is most pronounced in the dependent portion of the lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of nonionic and ionic contrast agents in the rabbit lung.

The objective of this study was to determine the short- and long-term radiographic, physiologic and histologic changes elicited in the lung of rabbits following the aspiration of commonly used radiographic contrast agents. All agents used, including nonionic agents, caused radiographically evident pulmonary edema which cleared by 24 hours. The contrast materials with higher osmolality, viscosity, and iodine content elicited the greatest physiologic and pathologic changes. No differences were found between an ionic and a nonionic agent with similar viscosities and iodine content, despite a lower osmolality in the nonionic agent. No contrast agent is innocuous when introduced into the lung.

Use of capillary optics as a beam intensifier for a Compton x‐ray source

The use of Kumakhov capillary optics will significantly enhance the performance of near-monochromatic, Compton backscattered x-ray programs. The Vanderbilt University Medical Free-Electron Laser Center is developing the capability to create these tunable x rays for medical imaging. The present transport has only reflection optics, and the beam is quite large in diameter at the laboratory. Low loss collimation of this beam would allow higher x-ray intensities after transport. This article describes experimental and computer simulation results which predict the expected performance for a multifiber Kumakhov collimator for use in the x-ray beam transport. Estimates from our research are that a multifiber optic formed of individual polycapillary fibers could be used to capture the full 7 mrad of the Vanderbilt x-ray beam and collimate it to a 1-2 mrad divergence with approximately 40%-50% transmission efficiency. This optic should increase the x-ray intensity at the laboratory level by a factor of > or = 5 by decreasing the beam divergence and subsequent spot size. Additionally, analysis of monolithic optics of fused multicapillary fibers predicts an increase in the intensity of the x rays at the laboratory by a factor of 55. These optics can have tapered channels that greatly decrease their exit divergence. This will greatly enhance the capabilities of this unique x-ray source. This article reports the initial results from a collaboration between Vanderbilt, The Center for X-Ray Optics at University at Albany, SUNY, and X-Ray Optical Systems in Albany, NY.

Development of the Vanderbilt Compton X-ray facility

Abstract The intense IR photon output of the Vanderbilt FEL is to be made to collide with its own high-energy electron beam to create nearly monochromatic Compton backscattered X-rays. At Vanderbilt, a sub-project of FEL-generated X-rays is under development parallel to the construction and initial operation of the FEL main project. The electron beamline and IR photon beamline designs are near completion, including design of electron beamline magnets and their layout, design of IR optical beamline elements and their layout, electron and IR optical beam diagnostics and alignment methods.

The Hermansky-Pudlak Syndrome

Hermansky-Pudlak Syndrome (HPS) is a rare, inheritable disorder characterized by the classic triad of oculo-cutaneous albinism, platelet dysfunction, and ceroid deposition. An associated complication is pulmonary fibrosis with progressive restrictive lung disease. This report discusses the lung involvement often seen in this condition correlated with radiography, computed tomography, high-resolution computed tomography, and the underlying pathology, by means of two such afflicted siblings. The elder died of respiratory failure while awaiting lung transplantation. The younger sibling is currently undergoing evaluation for transplantation.