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J A Patton

Publications and source records attributed to J A Patton.

At least 37 records · Page 2Linked to original sources
PubMed1995

FDG-SPECT: correlation with FDG-PET.

UNLABELLED: The clinical utility of FDG-PET imaging in the evaluation of patients with cardiac, oncologic and neurologic diseases is well documented. The major disadvantages of PET continue to be its high cost and limited availability. METHODS: With the goal of providing equivalent diagnostic information using a widely available, less expensive modality, we evaluated the clinical utility of FDG-SPECT imaging with a conventional dual-headed camera as compared to PET in 21 patients. RESULTS: To compare the image quality of the two modalities, major physical parameters and phantom determinations were obtained. By using the 511-keV collimators, we achieved resolution and system volume sensitivity that were less than those for PET by factors of 2.6 and 8, respectively. The SPECT system, on the other hand, could easily resolve 2 x 0.5-cm cold defects in the heart phantom and 2-cm hot lesions in a 22-cm cylindrical phantom with a target-to-background ratio of 5:1. FDG-SPECT imaging of nine patients with heart disease yielded similar diagnostic information of the amount of viable myocardium present when compared to PET. In seven of eight patients, malignant tissue visualized with FDG-PET was seen equally well with SPECT. The lesions not visualized with FDG-SPECT were either small (< or = 1.5 cm) or benign. SPECT imaging of four patients with cerebral lesions was inconclusive due to the small sample size but seemed promising. CONCLUSION: FDG-SPECT with 511-keV collimation is less expensive, more available and technically simpler than PET. We believe that FDG-SPECT has achieved sufficient sensitivity and resolution to detect myocardial viability and diagnose malignant tumors > or = 2 cm in diameter.

Adult↗
PubMed1994

MR imaging instrumentation and image artifacts.

Current magnetic resonance (MR) imaging systems use four basic types of magnets: permanent, resistive (electromagnets), hybrid (combines principles of permanent and resistive magnets), and superconducting (resistive-like magnets cooled to near absolute zero to achieve superconductivity). The first three have relatively low field strength (0.2-0.6 T) compared with superconducting magnets (2.0 T), but they cost less, have limited fringe fields, and have minimal sitting restrictions. Although current low-field-strength units have signal-to-noise ratios competitive with those of high-field-strength superconducting units, the latter still allow faster data acquisition. Use of shim coils improves the uniformity of the primary magnetic field and thus image quality. However, distortions may be incurred depending on the magnetic susceptibility of materials being imaged or chemical shift effect. Image nonuniformities can result from the interactions between the shim coils and gradient coils, which are used to create the high-performance linear gradients needed in many MR techniques (eg, gradient-echo and echo-planar imaging). The gradient coils must be shielded to prevent these eddy current effects. The imager must also be shielded from external radio-frequency signals, which can cause interference. Image degradation caused by respiratory motion, cardiac motion, and blood flow can be reduced by use of gating and special imaging techniques.

Artifacts↗
PubMed1992

Clinical impact of picture archiving and communication systems: evaluation of a prototype system.

Opinion surveys were gathered before and 6 months after installation of a prototype picture archiving and communication system (PACS) (PACS/1, Siemens Medical Systems, Iselin, NJ). Median turnaround times and the percent of delayed or missing reports were calculated for 1,026 baseline and 8,438 follow-up studies at 6 months. Neuroradiological (neuro) computed tomography (CT) used PACS, while neuro magnetic resonance (MR), body CT, and body MR served as controls. The opinion surveys showed improved service in all categories, including those not directly affected by PACS. PACS images favorably impressed 86% of respondents, but most considered the system too slow, unreliable, and the storage capacity too low. A majority of 81% recommended against purchase of PACS now. There was an overall increase in the median report turnaround time for both neuro CT and the controls. Neuro CT showed a 41% decrease in delayed or missing reports, but controls also showed similar decreases. The effects of this prototype PACS on turnaround time or on report delivery could not be distinguished from section-wide changes in CT and MR services. Future improvements in PACS should vigorously address increased speed, reliability, and storage capacity.

Attitude of Health Personnel↗
PubMed1990

Qualitative and quantitative evaluation of charge capture by a radiology information system.

Installation of a radiology information management system (RIS) is usually justified on the basis of improved departmental efficiency and improved charge capture. However, evaluation of the success of these expected improvements is often difficult. The installation and operation of such a system in a medium-sized tertiary care hospital has permitted the effects of the RIS on the operation of the department to be studied and the improvements in charge capture provided by the system to be quantitatively assessed. As a result of a side-by-side comparison with a conventional check-sheet manual billing system, it is apparent that the RIS reduces the errors inherent in manual systems. Subjectively, it is also apparent that personnel prefer the computerized system to the manual charge sheets.

Accounting↗
PubMed1990

Recent advances in thyroid imaging.

Thyroid imaging has evolved from early radionuclide rectilinear thyroid scanning to the recently developed technique of single photon emission computed tomography. At the same time, x-ray fluorescent scanning, ultrasound, computed tomography, magnetic resonance imaging, and positron emission tomography have improved identification of the thyroid gland. The appropriate use and relative roles of these imaging modalities in the investigation of patients with thyroid disease are discussed.

Diagnostic Imaging↗
PubMed1989

Multimodality imaging of the thyroid gland.

The continued development of high technology in the rapidly expanding field of computer-based imaging has had a significant impact on many areas of diagnostic imaging. The problem of rising medical costs emphasizes the importance of reaching a diagnosis by the most straightforward and cost-effective method while providing minimal patient discomfort. This responsibility to the patient and the medical care system rests with the physician. It is therefore essential that both imaging and referring physicians have a broad background of information regarding the potential limitations and relative merits of both old and new technologies available to patients with thyroid disorders. The appropriate utilization and relative roles of these imaging modalities have been discussed with respect to the individual clinical problem in this chapter.

Diagnostic Imaging↗
PubMed1988

Thyroid carcinoma masquerading as a solitary benign hyperfunctioning nodule.

Focal hot nodules on iodine thyroid images are associated with an exceedingly low incidence of malignancy. Most previously reported hot carcinomas represent the coexistence of small malignancies in or adjacent to a benign hot lesion. Described here is a 3-cm papillary carcinoma that fulfilled the criteria for benignancy on Tc-99m and I-123 imaging. Coincidental carcinoma within a benign lesion was excluded by detailed scintigraphic-pathologic correlation of the tumor. The implications of this case on the management of the solitary hot nodule are discussed and the literature reviewed.

Aged↗
PubMed1987

Quantitative evaluation of postembolized splenic tissue using technetium-99m sulfur colloid.

Tc-99m sulfur colloid scans were used to quantitate the percent of residual splenic tissue after partial splenic embolization (PSE) performed for the treatment of hypersplenism in 17 renal transplant patients. A liver-spleen phantom was designed which simulated the human liver and spleen configuration to evaluate the technique. This phantom contained a solution of tc-99m sulfur colloid, which allowed precise quantities of the spleen phantom volume to be displaced using lucite pseudo-emboli. After each lucite embolus, computer images of the spleen phantom were collected and analyzed in the same manner used for the transplant patients. Correlation of the actual volume displaced or embolized with the computer estimated values was 0.996 (P less than 0.001). This technique was superior to both CT and MRI, which were more difficult to perform and less precise in measuring a decrease in postinfarction functioning splenic tissue.

Embolization, Therapeutic↗
PubMed1987

Craniotomy flap osteomyelitis: a diagnostic approach.

Nine cases of suspected craniotomy flap osteomyelitis evaluated by combined bone and gallium scanning are presented. In six cases, the clinical data were inconclusive and evaluation by radionuclide imaging provided an accurate negative diagnosis. The other three cases considered positive by this technique were proven infected at subsequent exploration and flap removal. The use of radionuclide bone and gallium imaging should be considered in cases of possible craniotomy flap osteomyelitis.

Adolescent↗
PubMed1987

Multimodality imaging of the thyroid and parathyroid glands.

Nuclear imaging of the thyroid and parathyroid glands has evolved from early radionuclide rectilinear thyroid scanning to the recently developed dual isotope subtraction technique for detecting parathyroid lesions. At the same time, x-ray fluorescent scanning, ultrasound, x-ray computed tomography, and magnetic resonance imaging have improved identification of these endocrine organs. The appropriate use and relative role of these imaging modalities in the investigation of patients with thyroid and parathyroid diseases is discussed.

Adenoma↗
PubMed1986

Serial thyroid iodine content in hyperthyroid patients treated with radioiodine.

X-ray fluorescent scanning was used to measure initial thyroidal iodine content in 64 patients diagnosed as being hyperthyroid and selected for I-131 therapy, and serially in 48 of these patients after therapy in an attempt to determine those patients that were at high risk of becoming hypothyroid. Iodine content fell rapidly after therapy, reaching a nadir at about three months. Based on the population studied, the chance of early hypothyroidism (within 12 months) is about 80% if the iodine content measured at three months is less than 2 mg. If the iodine content is greater than 2 mg, the chance is only about 14%. The serial measurement of thyroidal iodine content (with x-ray fluorescent scanning) may allow early identification of those patients at high risk of developing permanent hypothyroidism following a therapeutic dose of I-131.

Female↗
PubMed1986

Technical considerations for the use of surface coils in MRI.

The signal-to-noise response characteristics for two surface coils of different construction geometries (a single-turn planar coil and a single-turn saddle-shaped coil) were measured and compared with head and body coils. Measurements were made at different gradient magnifications (0, 20, 30, and 40%, relative to the head coil) and with different numbers of signal averages (3, 8, 12, and 18). The signal-to-noise curves were used to guide the selection of surface coils for use in clinical studies. This technique is useful in determining the optimal technique for specific clinical problems evaluated by surface-coil imaging. For the planar (flat) surface coils, the signal-to-noise per pixel was found to be superior to the conventional head coil at depths equal to or less than 5 cm. For the saddle coil, signal-to-noise per pixel was superior to the head coil for depths below 8.5 cm for magnifications up to 30%. For the 40% magnification, the depth at which the signal-to-noise was equal to the head coil decreased to about 6 cm. Surface coils have demonstrated a marked improvement in signal-to-noise relative to conventional head and body coils for superficial structures.

Facial Nerve↗