Three-dimensional morphology of the distal part of the femur viewed in virtual reality.
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Biomechanical Phenomena↗
Biomedical subjects
V M Spitzer
Publications and source records attributed to V M Spitzer.
The Visible Human Dataset: the anatomical platform for human simulation.
One goal of a medical school education is to teach the anatomy of the living human. With the exception of some surface anatomy, the morphology education that goes on during a surgical procedure, and patient observation, live human anatomy is most often taught by simulation. Medical anatomy courses utilize cadavers to approximate the live human. Case-based curricula simulate a patient and present symptoms, signs, and history to mimic reality for the future practitioner. Radiology has provided images of the morphology, function, and metabolism of living humans but with images foreign to most novice observers. With the Visible Human database, computer simulation of the live human body will provide revolutionary transformations in anatomical education.
Anatomy, Cross-Sectional↗
More real-time visual and haptic interaction with anatomical data.
The University of Colorado's Center for Human Simulation has developed fundamental algorithms for real-time visual and haptic interaction with polygonal and voxel base data sets, including those derived from the Visible Human Dataset. These algorithms are currently being used to create prototype simulators for surgery, needle insertion (anesthesiology, radiology, and rheumatology), dentistry, and ophthalmology. This paper briefly discusses our segmentation and classification effort as well as our ability to create texture-mapped polygonal models directly from the data: both are fundamental to the creation of anatomically based simulators.
Algorithms↗
The visible human: a new language for communication in health care education.
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Anatomy, Cross-Sectional↗
The Ranawat Award. Sulcus morphology of the distal femur.
Traditional images of the distal femur place the intercondylar groove midway between the condyles. The location of the sulcus of the intercondylar groove in a large Sudanese skeletal population was verified using a custom stereotactic device. The results of this study show that the femoral sulcus is lateral to the midplane between the 2 femoral condyles. This study also shows that the configuration of the sulcus is linear and is oriented between the traditional anatomic and mechanical axes of the femur.
Adult↗
Real-time visually and haptically accurate surgical simulation.
The Visible Human Database provides a complete submillimeter photographic and radiological description of both a male and a female cadaver. The Center for Human Simulation has developed real-time algorithms that allow a user to wield a virtual scalpel and produce arbitrary cuts into the reconstructed body. Real-time interaction is achieved by producing the appropriate texture mapped surfaces directly from the Visible Human Database. We are currently combining a 3 degree of freedom PHANToM haptic device (SensAble Devices) with our surgical cutting algorithms to produce a system with the look and feel of surgical cutting.
Anatomy, Cross-Sectional↗
The Visible Human data set: an image resource for anatomical visualization.
The National Library of Medicine (NLM) has long been a world leader in the archiving and distribution of the print-based images of biology and medicine. NLM has also been a pioneer in the use of computer systems to encode and distribute textual knowledge of the life sciences. NLM's Long Range Planning effort of 1985-86 foresaw a coming era where NLM's bibliographic and factual database services would be complemented by libraries of digital images, distributed over high speed computer networks and by high capacity physical media. The NLM Planning Panel on Electronic Imaging recommended that NLM should undertake the building of a digital image library consisting of computer-assisted tomography (CAT), magnetic resonance interferometry (MRI), and cryosection images of a representative, carefully selected and prepared male and female cadaver--the "Visible Human Project." The male Visible Human data set is now being made available through a license agreement with the NLM. A wide range of educational, diagnostic, treatment planning, and commercial uses is predicted. The Visible Human data set and its associated identification maps will serve as a "Boston Teapot" for medical imaging, a common public domain data set against which all medical imaging algorithms can be tested, and a cornerstone for future sets of related image libraries.
Adult↗
High resolution electronic imaging of the human body.
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Anatomy↗
Three monochrome displays from a single, true color video display controller.
Some nuclear medicine computer displays, as well as many image processing workstations are "true color" machines characterized by independent memory and grey scale mapping for each of the red, green and blue color channels. Other color image display systems produce a color image from a single grey scale map composed of red, green, and blue intensity values ("pseudo color"). In the true color system the final image is obtained by overlays of three independent color images. In an effort to present complete nuclear medicine studies for diagnosis from cathode-ray tubes (CRTs) we have employed a true color display to present three times as much spatial information as the system was designed for by directing each color output from the display controller to a different monochrome black and white (b/w) monitor. Therefore our system displays a 512 x 512 x 24-bit true-color image, or three 512 x 512 x 8-bit monochrome images, or any combination of smaller size matrices. Monitor requirements, cabling, and general software considerations are detailed here. The ability to display complete nuclear medicine studies on CRTs (as currently presented on film) has been provided by adding monitors and software revisions to a commercially available nuclear medicine computer system.
Color↗
Detection of low-contrast signals. A comparison of observers with and without radiology training.
Sixteen observers averaging 7.4 years experience in interpreting radiology images and 16 observers without radiology training were tested for their ability to detect low-contrast signals in structured noise backgrounds using a digital display system. No significant difference in true positives, false positives, time to complete test, or a calculated "performance value" could be detected between the two groups. Data from the beginning and end of the test indicated that no difference in performance between groups evolved as the test progressed. Therefore, radiology training seems to offer no significant advantage in low-contrast signal detection in an unfamiliar structured noise background, nor in rapid development of better search strategies or decision criteria.
Adult↗
Clinical comparison of technetium-99m-N,N-bis(mercaptoacetyl)-2,3-diaminopropanoate with technetium-99m DTPA for renal imaging.
We studied 14 patients having serum creatinines of 1.0 to 12.8 mg/dl with either Tc-99m-N,N'-bis(mercaptoacetyl)-2,3-diaminopropanoate (CO2-DADS) or Tc-99m DTPA, and within 48 hours with the other agent. Analog and digital images of the kidneys and bladder were acquired for 30 minutes after injection and after voiding. The kidney-to-background ratio at 3 minutes for Tc-99m CO2-DADS was 2.01 +/- 0.79 (mean +/- SD) times that for Tc-99m DTPA (P less than 0.001). The parenchymal transit time for Tc-99m CO2-DADS was 1.34 +/- 0.25 (mean +/- SD) times that for Tc-99m DTPA (P less than 0.005). The percent-excreted dose at 30 minutes for Tc-99m CO2-DADS was 2.57 +/- 1.24 (mean +/- SD) times that for Tc-99m DTPA (P less than 0.001). Analog Tc-99m CO2-DADS images showed spatial resolution comparable to that for Tc-99m DTPA. Hepatobiliary excretion was never seen. Tc-99m CO2-DADS appears to be generally superior to Tc-99m DTPA as a renal radiopharmaceutical.
Alanine↗
Clinical evaluation of Tc-99m N,N'-bis(mercaptoacetyl)-2,3-diaminopropanoate as a replacement for I-131 hippurate: concise communication.
A clinical comparison of Tc-99m N,N'-bis( mercaptoacetyl )-2,3- diaminopropanoate (Component A) (Tc-99m CO2-DADS-A) and I-131 hippurate was conducted in a series of five normal volunteers and 18 patients. Each subject was studied in one session with Tc-99m CO2-DADS-A and I-131-hippurate; digital and analog images were recorded for 30 min and after voiding. In the normal volunteers, digital images with Tc-99m CO2-DADS-A gave a kidney-to-background ratio at 3 min that was greater relative to I-131 hippurate, a leading-edge parenchymal transit time that was similar to I-131 hippurate, and a percent injected dose in the urine at 30 min that was slightly less than I-131 hippurate (p less than 0.05). In patients (serum creatinine 1.0 to 14.3 mg/dl), decreasing renal function impaired excretion of Tc-99m CO2-DADS-A more than that of I-131 hippurate (p less than 0.01). In analog images, Tc-99m CO2-DADS-A always gave superior spatial resolution. No evidence of hepatobiliary excretion was detected with either radiopharmaceutical. We conclude that Tc-99m CO2-DADS-A and similar compounds should be pursued as possible replacements for I-131 hippurate.
Alanine↗
Practicality of NEMA performance specification measurements for user-based acceptance testing and routine quality assurance.
National Electrical Manufactures Association ( NEMA ) performance specifications provide the only standardized and traceable measurements of scintillation-camera performance that are widely accepted by manufacturers. The NEMA publication describing the performance specifications suggests that elaborate equipment beyond a standard imaging computer is required for the measurements. For this reason the tests are currently unsuitable for both user-based acceptance testing and daily quality assurance. We have implemented five of the eight NEMA performance measurements as routine quality-assurance procedures on our computerized scintillation cameras. In addition, we have shown that seven of the eight NEMA measurements can be performed in a manner traceable to NEMA , with energy resolution as the single exception. With a standard imaging computer, NEMA phantom, and minor modification to NEMA collection and analysis constraints, we have analyzed images for intrinsic uniformity, resolution, linearity, and multiple-window spatial registration as well as for system spatial resolution both with and without scatter.
Computers↗
Work in progress: clinical evaluation of Tc-99m-trimethylbromo-IDA and Tc-99m-diisopropyl-IDA for hepatobiliary imaging.
Six healthy individuals and six patients with a wide range of hepatobiliary function abnormalities were studied with Tc-99m-trimethylbromo-IDA; all normal subjects and four of the six patients were also studied with Tc-99m-diisopropyl-IDA. Visual evaluation of analog images demonstrated a greater liver-to-kidney ratio for Tc-99m-trimethylbromo-IDA (p less than 0.01). Sampling for radiopharmaceutical in urine at three hours following injection demonstrated that Tc-99m-trimethylbromo-IDA had a lower renal excretion rate than Tc-99m-diisopropyl-IDA regardless of whether hepatocyte function was normal or abnormal (p less than 0.01). There were no significant differences between the two radiopharmaceuticals in hepatocyte extraction efficiency or hepatic parenchymal transit time. It is concluded that the lower rate of renal excretion and, therefore, greater hepatocyte specificity of Tc-99m-trimethylbromo-IDA justifies expanded clinical trials and may make it the radiopharmaceutical of choice for hepatobiliary imaging.
Adult↗
Normal appearance and reproducibility of liver-spleen studies with Tc-99m sulfur colloid and Tc-99m microalbumin colloid.
In order to determine the normal biodistribution and reproducibility of Tc-99m sulfur colloid and Tc-99m microalbumin colloid, each of ten normal subjects was studied twice with each of the two agents. In overexposed delayed analog images of the anterior chest, some thyroid radioactivity was demonstrated in all of 20 microalbumin colloid studies and in none of 20 sulfur colloid studies; lung radioactivity was seen in 19 of 20 (95%) sulfur colloid studies and in none of the microalbumin colloid studies (both p less than 0.001). Delayed digital images showed that the sulfur colloid gave a higher lung-to-heart ratio, a higher lung-to-liver ratio, and a lower bone marrow-to-liver ratio compared with microalbumin colloid (all p less than 0.05). In general, reproducibility was poor for both agents. We conclude that while there are some differences between these two radiocolloids, the differences do not indicate a superiority of the newer Tc-99m microalbumin colloid over the established Tc-99m sulfur colloid for liver-spleen imaging.
Adult↗
Clinical comparison of Tc-99m N,N'-bis(mercaptoacetamido)ethylenediamine and [131I]ortho-iodohippurate for evaluation of renal tubular function: concise communication.
Recent experiments in normal animals have shown that Tc-99m N,N'-bis(mercaptoacetamido)ethylenediamine (Tc-99m DADS) is a potential technetium-99m-labeled replacement for [131I]ortho-iodohippurate(I-131 Hipp). We compared the two agents in eleven patients with renal transplants (serum creatinine range: 0.9--5.7 mg/dl). Digital and analog images were recorded for 30 min and after voiding. The results indicate that the relative extraction efficiency index of Tc-99m DADS is 76% +/- 3 (mean +/- s.e.m.), that the leading-edge parenchymal transit time of Tc-99m DADS is 137% +/- 6, and that the percentage of injected Tc-99m DADS in the bladder at 30 min is 25% +/- 4 of that of I-131 Hipp (all p less than 0.05). Forty percent of patients showed some hepatobiliary excretion of Tc-99m DADS. We conclude that the biologic properties of Tc-99m DADS are inferior to those of I-131 Hipp and that analogs of Tc-99m DADS should be evaluated in an attempt to find a more suitable technetium-99m-labeled replacement for I-131 Hipp.
Animals↗
Clinical comparison of diisopropyl-IDA Tc 99m and diethyl-IDA Tc 99m for evaluation of the hepatobiliary system.
Thirty-one patients with a wide range of hepatobiliary function and clinical diagnoses were studied with both diisopropyl-IDA Tc 99m and diethyl-IDA Tc 99m. Images were similar except for an increased liver-to-kidney ratio with diisopropyl-IDA Tc 99m (p less than 0.01) and a tendency toward an increased liver-to-background ratio at five minutes with diisopropyl-IDA Tc 99m (p greater than 0.05). Quantification of the relative hepatocyte extraction efficiency indicated a 16% higher extraction efficiency for diisopropyl-IDA Tc 99m (p greater than 0.05). Cumulative three-hour urine collections following injection demonstrated no significant difference in renal excretion in patients with normal total serum bilirubin levels. Both radiopharmaceuticals demonstrated increasing renal excretion with increasing total serum bilirubin levels; however, renal excretion of diisopropyl-IDA Tc 99m increased more slowly than excretion of diethyl-IDA Tc 99m (p less than 0.01). We conclude that, while the overall differences between these two radiopharmaceuticals are small, diisopropyl-IDA Tc 99m is superior because of a lower renal excretion rate in patients with decreased hepatocyte function.
Bile Duct Diseases↗
Single-composite image display of information from tomographic myocardial perfusion studies.
Tomography has the general advantage of improving spatial resolution in a direction perpendicular to the tomographic sections. However, visualizing the size, shape, and relative position of a lesion depicted in multiple tomograms can be difficult. The authors have developed computer software which permits the single-composite display of information contained in multiple tomographic sections from a thallium-201 myocardial perfusion study. The display also allows identification of left ventricular myocardial areas as normal, reversibly ischemic, or irreversibly ischemic and quantitates the per cent of myocardium in each category.
Coronary Circulation↗