ABSTRACT
The ability of an intravascular ultrasound catheter to give cross-sectional images of vessel walls and surrounding tissues, and the behavior of ultrasound in heterogeneous media, are at the origin of degradation of image quality. Qualitative and quantitative analyses of in vivo studies are then operator-dependent and are limited by artifacts. We investigated these limitations by an in vitro study on plexiglass phantoms and segments of fresh arteries. We used a 20 MHz transducer mounted on the tip of a 4.8 F catheter and an interventional ultrasound system. The ultrasound beam is reflected onto the rotating transducer at 600 rotations per minute (RPM), creating 360 degrees real-time images (10 images/second). We then observed, analyzed and interpreted the most specific reasons for image artifacts: geometric distortions, multiple echoes, the point spread function (PSF) of the imaging system, near-field effects, "petal-shaped" effect, and ultrasound speckle. Various practical implications have resulted from this study. Only a thorough knowledge of how to avoid some of the most obvious pitfalls will enable the user to obtain maximum benefits from intravascular ultrasound imaging, and to appreciate its limitations.
Subject(s)
Artifacts , Ultrasonography, Interventional/methods , Arteries/diagnostic imaging , Arteries/pathology , Arteriosclerosis/diagnostic imaging , Arteriosclerosis/pathology , Catheterization , Humans , Image Processing, Computer-Assisted , Mathematics , Models, Structural , TransducersABSTRACT
The increasing use of intravascular ultrasound technology by clinicians is providing detailed and immediate information about the results of interventions, and this is stimulating the development of new catheters that use ultrasound imaging to control therapy in real time. Cold and thermal balloon angioplasty, atherectomy, embolectomy, laser ablation and rotational recanalization are a few of the interesting capabilities now being added to ultrasound catheters. We report on the development and characteristics of some of these devices and attempt to assess their potential to precisely direct therapy.
Subject(s)
Angioplasty, Balloon/instrumentation , Catheterization/instrumentation , Ultrasonography/instrumentation , Angioplasty, Laser/instrumentation , Electrocoagulation/instrumentation , Humans , Transducers , Ultrasonography/methodsABSTRACT
Clinical experience with 6 and 9 Fr ultrasound imaging catheters (UICs) reveals that several transducer and catheter tip varieties are needed for optimum imaging of diseased intravascular sites. Our UIC design has combined established catheter design and very high frequency ultrasound imaging technology to create a versatile, user configured system for intravascular ultrasound imaging. Optimum use requires proper strategic selection of transducer and catheter sizes, frequencies of operation, and interventional accessories.
Subject(s)
Angioplasty, Balloon/instrumentation , Arterial Occlusive Diseases/diagnosis , Muscle, Smooth, Vascular/pathology , Ultrasonography/instrumentation , Cardiac Catheterization/instrumentation , Coronary Disease/diagnosis , Humans , TransducersABSTRACT
Postmortem findings are presented for fourteen cases of Verapamil induced or related deaths. Liver, blood, and stomach concentrations of Verapamil alone or in combination with alcohol or other drugs are given with the age and sex of each victim and with the coroner's findings. The significance of these levels is discussed. Tissue homogenates were digested either by strong acid or enzymically by subtilisin and extracted with dichloromethane or 1-chlorobutane, respectively. Blood was buffered to pH 9 and extracted directly with 1-chlorobutane. Recoveries are reported. Verapamil was quantitated by gas chromatography on a 3% OV-17 column with a nitrogen-phosphorus detector.
Subject(s)
Verapamil/poisoning , Adolescent , Adult , Aged , Female , Humans , Hydrogen-Ion Concentration , Liver/analysis , Male , Metoprolol/analysis , Middle Aged , Verapamil/analysisABSTRACT
N,N-diethyl-m-toluamide (DEET) levels in postmortem specimens of stomach and contents, blood, liver, and urine are reported following ingestion of the compound. DEET was analyzed by gas chromatography with an OV-101 column and a nitrogen phosphorus detector. The presence of the compound in the four postmortem specimens was confirmed by mass spectrometry.
Subject(s)
Autopsy , Benzamides/analysis , DEET/analysis , Chromatography, Gas/methods , DEET/blood , DEET/urine , Humans , Liver/analysis , Stomach/analysisSubject(s)
Dental Auxiliaries , Personnel Management , Personnel Selection , Humans , Practice Management, DentalABSTRACT
Phosphine was detected in post mortem stomach and contents, blood, and liver specimens of a man who had ingested tablets containing aluminium phosphide. The phosphine was released from the samples after acid treatment and analysed by means of a headspace gas chromatographic technique using a nitrogen phosphorus detector.
Subject(s)
Aluminum Compounds , Phosphines/analysis , Phosphines/poisoning , Chemical Phenomena , Chemistry , Ditiocarb , Gas Chromatography-Mass Spectrometry , Humans , Silver NitrateABSTRACT
Postmortem samples from two fatalities involving parathion ingestion were examined. Parathion could not be detected in the liver tissue but a significant quantity of a related compound was detected. This was shown to be aminoparathion, a biotransformation product of parathion. The substances were extracted with hexane and analyzed by gas-liquid chromatography on a 3% OV-210 column. Thin-layer chromatography and mass spectrometry were also performed. The transformation of parathion to aminoparathion in human tissue has not been previously reported.
