William J. Zwiebel

Computerized Fluoroscopy in Real Time for Noninvasive Visualization of the Cardiovascular System

A computerized fluoroscopic system with dedicated real-time hard-wired algorithms can be used for cardiovascular imaging with or without injection of iodine. Initial differentiated and integrated time subtraction displays are presented. Contrast studies appear adequate for visualization of cardiovascular dynamics. Cardiac images without contrast material suggest expected blood flow patterns but are difficult to interpret.

Computed tomography of the retroperitoneum following nephrectomy.

Twenty-five patients were examined by computed tomography (CT) after nephrectomy. CT was useful in the detection of postoperative complications and local recurrence of tumor. Ultrasound was difficult because of rib artifacts or bowel gas, and a fluid-filled bowel often simulated tumor: oral contrast material was useful during CT. Local recurrence was demonstrated by CT in 8 patients in whom it was clinically suspected. Recurrent tumor was simulated by scarring in 3 cases and by an accessory or residual spleen in 2. Operative complications included one hematoma and one retroperitoneal abscess. CT could be useful in following up selected patients after nephrectomy.

Computerized Fluoroscopy Techniques For Non-Invasive Cardiovascular Imaging

A number of methods for visualizing the cardiovascular system of dogs and humans in real time have been developed and are grouped under the heading computerized fluoroscopy. Such techniques provide images capable of high contrast sensitivity and moderate spatial resolution (~ 1 mm). A standard image intensifier - television chain used in connection with a Lpecially constructed digital video image processor (V.I.P.) is capable of producing contrast enhanced difference images at rates up to 60/second. Such difference images can isolate small concentrations of iodine which have been administered intravenously through peripheral veins. Such non-invasive techniques have been used to visualize: 1) The carotid arteries and fine structures in dogs and humans at typical rates of 2 per second, and 2) the heart chambers of both dogs and humans at typical display rates of 15-60 per second. For such studies 0.6-1.0 gms (Iodine)/kg (body mass) have provided excellent visualization of the cardiac chamber dynamics.

Real-Time Computerized Fluoroscopic Cardiac Imaging

A computerized fluoroscopy system employing several time and energy subtraction algorithms has permitted good visualization of the cardiovascular system using peripheral intravenous iodine injections of about 1 cm3/kg. Image contrast im-provements of 8-16 over conventional fluoroscopy are common. Several canine and human imaging studies are described including visualization of myocardial infarc-tions as regions of anomalous image grey shade. The system employs a standard image intensified fluoroscopy system and a specially constructed real-time image processor. Quasimonoenergetic x-ray beams formed by filtration deliver typical doses of 400 mR/sec in adult human cardiac exams.

Doppler Ultrasound Evaluation of Extracranial Cerebrovascular Disease

Carotid Doppler examination was compared with arteriographic findings in 125 patients. The results demonstrated exact correlation in 87% of vessels studied. Clinically significant errors occurred at a rate of 4.5%. Clinically insignificant errors (8.5%) were usually the result of wall disease being mistaken for nonhemo-dynamically significant stenosis.