ABSTRACT
OBJECTIVE: To assess the potential of optical coherence tomography (OCT) to differentiate retinoschisis from retinal detachment. Optical coherence tomography is a noninvasive, noncontact imaging method that produces high-resolution, cross-sectional images of ocular tissue. DESIGN: Retrospective case series. PARTICIPANTS: Thirteen eyes of 12 patients with the differential diagnosis of retinoschisis versus retinal detachment. METHODS: Differentiation between retinoschisis and retinal detachment was established from both ophthalmoscopic and OCT examinations. MAIN OUTCOME MEASURE: Ability of OCT to differentiate retinoschisis from retinal detachment was measured. RESULTS: Thirteen eyes of 12 patients with retinal elevation were examined with OCT. The cross-sectional view produced by OCT was effective in distinguishing retinoschisis from retinal detachment. Optical coherence tomography images of retinoschisis show a splitting of the neurosensory retina. The OCT images of retinal detachment show separation of full-thickness neurosensory retina from the retinal pigment epithelium band. The OCT images correlated with the clinical impression in all 13 cases. CONCLUSIONS: Based on this series of cases, OCT is a potentially useful new test that may be used to distinguish retinoschisis from rhegmatogenous retinal detachment.
Subject(s)
Diagnostic Techniques, Ophthalmological/instrumentation , Retina/pathology , Retinal Degeneration/diagnosis , Retinal Detachment/diagnosis , Tomography/methods , Adult , Aged , Diagnosis, Differential , Female , Fundus Oculi , Humans , Image Processing, Computer-Assisted , Male , Middle Aged , Retrospective StudiesABSTRACT
Two healthy volunteers who had inhaled approximately 0.75 L of laser-polarized helium-3 gas underwent magnetic resonance imaging at 1.5 T with fast gradient-echo pulse sequences and small flip angles ( < 10 degrees). Thick-section (20 mm) coronal images, time-course data (30 images collected every 1.8 seconds), and thin-section (6 mm) images were acquired. Subjects were able to breathe the gas (12% polarization) without difficulty. Thick-section images were of good quality and had a signal-to-noise ratio (S/N) of 32:1 near the surface coil and 16:1 farther away. The time images showed regional differences, which indicated potential value for quantitation. High-resolution images showed greater detail and a S/N of approximately 6:1.
Subject(s)
Helium , Lung/anatomy & histology , Magnetic Resonance Imaging/methods , Adult , Humans , Image Enhancement/methods , Isotopes , Magnetic Resonance Imaging/instrumentation , Male , Middle AgedABSTRACT
The authors imaged the lungs of live guinea pigs with hyperpolarized (HP) helium-3 as a magnetic resonance (MR) signal source. HP He-3 gas produced through spin exchange with rubidium metal vapor was delivered through an MR-compatible, small-animal ventilator. Two- and three-dimensional lung images acquired with ventilation-gated, radial k-space sampling showed complete ventilation of both lungs. All images were of high quality, demonstrating that HP He-3 allows high-signal-intensity MR imaging in living systems.
Subject(s)
Lung/anatomy & histology , Magnetic Resonance Imaging/methods , Animals , Guinea Pigs , Helium , Magnetic Resonance Imaging/instrumentation , Magnetic Resonance Imaging/statistics & numerical data , Male , RadioisotopesABSTRACT
A new optical transducer for the detection of acoustic pressure in the diagnostic ultrasound frequency range is described. This transducer is based on the modulation of an evanescent light field by the incident acoustic energy. Theoretical design considerations are presented for the purpose of developing the most sensitive transducer. Based on these considerations an experimental transducer was constructed. Although less sensitive than predicted this device was capable of transducing ultrasonic pulses with a 1.0-MHz center frequency at diagnostic ultrasound amplitude levels. The techniques developed here are applicable for two-dimensional transduction and may prove a viable alternative to piezoelectric array transducers.
Subject(s)
Transducers , Ultrasonography , Acoustics , Electromagnetic Fields , Equipment Design , Light , Models, Biological , Optical Rotatory DispersionABSTRACT
The rate constants for CO binding to the five-coordinate ferrous iron complexes of 5,10,15,20-[pyromellitoyl(tetrakis-o-oxyoxyphenyl)]porphyrin and 5,10,15,20-[pyromellitoyl(tetrakis-o-oxypropoxyphenyl)]porphyrin have been measured and compared with the corresponding rate constants for other hemes and hemoproteins. The second-order rate constant is independent of cap size and is comparable to that of high-affinity state hemoglobin (k5 approximately 4 X 10(6) M-1s-1). Therefore, these capped porphyrins provide no steric hindrance to CO binding. In addition, a kinetic scheme involving an unusual seven-coordinate porphyrin species is described.
