Robert M. Witt

Acetazolamide enhanced single photon emission computed tomography (SPECT) evaluation of cerebral perfusion before and after carotid endarterectomy

Twenty-five patients were tested before and after carotid endarterectomy with resting and acetazolamide enhanced single photon emission computed tomography (SPECT) scans with hexamethyl propyleneamine oxine (HMPAO) or iofetamine hydrochloride I123 (123I labeled IMP), both widely available radiopharmaceuticals. Twenty preoperative SPECT studies were asymmetric, revealing focal or diffuse decreased perfusion reserve, and 13 also demonstrated infarcts. Five patients had symmetric (normal) studies. After carotid endarterectomy, 22 cases had changed flow distribution patterns. Usually improvement of reactivity ipsilateral occurred to the area operated on. In four, contralateral improvement was also found. Three of the patients who had preoperative symmetrical scans had increased ipsilateral reactivity after surgery indicating previous global loss of reactivity. Acetazolamide SPECT scans demonstrate a decreased perfusion reserve in 20 patients with carotid artery stenosis, indicating reduced perfusion and poor collateral circulation. Postoperative studies confirm improvement by demonstrating recovery of vascular reactivity in 84% of the patients. Acetazolamide enhanced SPECT scans may be helpful in providing objective evidence for selection of patients for carotid endarterectomy, especially in those who have an 80% carotid artery stenosis, but are asymptomatic.

Potential radioprotective agents—VI. Chalcones, benzophenones, acid hydrazides, nitro amines and chloro compounds. radioprotection of murine intestinal stem cells

There is an interest and need for new compounds that protect tissues from radiation injury. In cancer therapy, the protection of normal tissue without protecting tumors is one way to increase the therapeutic gain. Thiol compounds are currently in clinical trials, but are limited to some extent by their human toxicities including hypotension, nausea, and emesis. Several new aminochalcones and aminobenzophenones were synthesized and tested for radioprotective activity in mice. All were less active than p-aminobenzophenone itself. Several acid hydrazides were synthesized and tested similarly, but none exhibited significant activity. The high radioprotective activity of 4-nitroaniline was confirmed, but other nitro amines were substantially less active. 4-Chloro-N-methylaniline is as active as 4-chloroaniline, but other chloro aromatics are devoid of significant activity. When compared with the phosphorothioate amyfostine (WR-2721) using the intestinal clonogenic cell survival assay, 1-(p-aminophenyl)-1-propanol (15), p-aminopropiophenone (16), its ethylene ketal (14), and a mixture of the two (17) protected to a great extent, though slightly less than WR-2721. These results suggest that there is direct cellular radioprotection by these non-thiol compounds. The studies further suggest that preclinical toxicity testing of the most protective agents is warranted.

Increased brain retention of Tc-99m HMPAO following acetazolamide administration.

Sixty-five patients rferred for Tc-99m HMPAO SPECT brain perfusion studies had measurements of global Tc-99m HMPAO retention after injection at rest and after acetazolamide pretreatment. Acetazolamide produced relative changes in Tc-99m HMPAO retention similar to those previously reported with Xe-133 regional cerebvral blood flow (rCBF) measurements. This adition to imaging protocols allows another objective evaluation of the cerebral vascular reserve.

Potential radioprotective agents—V. Melatonin analogs. Oral activity of p-Aminopropiophenone and its ethylene ketal

Seven new amides of 5-methoxytryptamine were synthesized and tested for radioprotective activity in mice. One of them, the heptafluorobutyramide 4, is moderately active (57% survivors), the rest demonstrate little or no activity. Of twelve compounds that had been found to exhibit high radioprotective activity by ip injection, only two [p-aminopropiophenone (9) and its ethylene ketal 8] retain that high activity (92-95% survivors) when administered orally. Three are moderately active: p-aminobenzonitrile (10, 55%), 5-methoxytryptamine octanoic amide (11, 50%), and p-aminobenzophenone (12, 48%).

Potential radioprotective agents — IV. Schiff bases

Twelve Schiff bases were prepared using salicylaldehyde, one with 5-chlorosalicylaldehyde, one with benzaldehyde, and a series of anilines substituted in the m- or p-positions. They were assayed for radioprotective activity in male, Swiss mice irradiated with a nearly lethal dose (950 cGy) of 6 mV photons produced by a linear accelerator, and were compared with the parent amines. Schiff base formation reduced toxicity of the parent amines; its effect on radioprotective activity was erratic, increasing activity in some cases, decreasing activity in others, and having no effect in still others. Radioprotective activity appears to be unrelated to a number of molecular descriptors. The highest radioprotection (100%) was observed for mixtures of p-aminopropiophenone with its Schiff base, or with the Schiff base of 1-(p-aminophenyl)-1-propanol (95%).

Integrating an enterprise image distribution system into an existing electronic medical record system

The enterprise distribution of radiology images should be integrated into the same application that physicians obtain other clinical information about their patients. Over the past year the Roudebush Veterans Affairs Medical Center has provided enterprise access to radiology images after integrating a commercial web-based image distribution system (Stentor, Brisbane, CA) with the Department of Veterans Affairs internally developed Computerized Patient Record System (CPRS). The application, CPRS, serves as the foundation for the VHA to implement an electronic medical record (EMR). We developed the necessary program communications between the CPRS application and the image distribution application to link the request for a report to a request for the corresponding images. When a physician selects a given radiology report in CPRS the text of the report displays in CPRS and the image application loads the corresponding image study. We found that the requests for film jackets decreased over fifty percent six months after full implementation of the enterprise image distribution system. We have found the integration of the image access and display application into an existing patient information system to be very successful.

Initial experience with a radiology imaging network to newborn and intensive care units

A digital image network has been installed in the James Whitcomb Riley Hospital for Children on the Indiana University Medical Center to create a limited all digital imaging system. The total system is composed of commercial components, Philips/AT&T CommView system, and connects an existing Philips Computed Radiology (PCR) system to viewing workstations located in the intensive care unit and the new born nursery. The purpose and design of the system is to input the portable chest images from the PCR system, and to display these images at the remote workstations on high resolution monitors for direct viewing by referring clinicians, thus eliminating some of their visits to the radiology department three floors away. The design criteria includes the ability to centrally control all image management functions on the remote workstations to relieve the clinicians from any image management tasks except for recalling patient images. The principal components of the system are the Philips PCR system, the acquisition module (AM), and the PCR interface to the data management module (DMM). Connected to the DMM are a display workstation (DW), a optical disk drive, and a fiber optic to ethernet gateway. The ethernet link is the network connection to the two results viewing stations (RVS) located approximately 100 meters from the DMM. The DMM acts as an image file server and image archive device. The DMM manages the image database and can load images to both the DWs and the two RVSs. The system has met the initial design specifications and can successfully capture images from the PCR and direct them to the RVSs. Additional studies are beginning to determine the optimal image management procedures such as when to archive and purge images from the DMM.

Evaluation Of Digital Image File Storage Requirements And Creation Rates

Estimates have been made for the amount of digital storage capacity necessary and the data creation rates for the nuclear medicine portion of an all digital radiology department. After installation, the number of computer studies performed, image files created and bytes archived for each month increased with time. There was a high correspondence between the number of computer studies performed and (1) the number of new image files created (r=0.95) and (2) the total number of pytes archived (r=0.82). The average number of bytes created per work-day was 5.6 x 106 Experience with our nuclear medicine system seems to indicate that when planning a picture archiving and communications system (PACS) installation (1) the amount of necessary online storage may increase and continue to increase after installation and (2) our estimate of nuclear medicine digital images creation rates agree with previous estimates l.