Iohexol vs. diatrizoate. A comparative study in intravenous urography.

A randomized double-blind study comparing the use of iohexol with diatrizoate in intravenous urography was performed in 435 patients in nine centers. Contrast media were evaluated for safety, incidence of adverse side effects, and efficacy. Multiple hematologic and biochemical parameters were observed, as well as blood pressure and pulse, at intervals before and after injection. Severity, nature, and duration of side effects were recorded together with the attending physician's clinical assessment. Coned radiographs of the kidneys were done immediately after injection and were repeated at 1-, 5-, 10-, and 20-minute intervals. Films were evaluated for quality of image. A significantly higher number of excellent studies were obtained with iohexol than with diatrizoate. Remarkably few side effects and adverse reactions reported for iohexol establish the safety and suitability of this nonionic contrast medium for intravenous urography.

Stability studies on chemoembolization mixtures. Dialysis studies of doxorubicin and lipiodol with Avitene, Gelfoam, and Angiostat.

RATIONALE AND OBJECTIVES: Chemoembolization, using a combination of embolic and chemotherapeutic agents, appears to be an effective treatment for hepatocellular carcinoma. Although the postulated mechanism of effectiveness hinges on a prolonged drug delivery, increasing evidence suggests that embolization mixtures are not stable. The objective of this study was to investigate examples of these mixtures. METHODS: Dialysis techniques have been used to examine the pharmacokinetic properties of chemoembolization mixtures that contain doxorubicin, Lipiodol (Guerbet Products, Montreal, Quebec), and the embolizing agents Avitene (Alcon Laboratories Inc., Fort Worth, Texas), Gelfoam (Upjohn, Kalamazoo, MI), and Angiostat (Regional Therapeutic Inc., Pacific Palisades, CA). RESULTS: Lipiodol, Gelfoam, and Avitene, when combined with doxorubicin, had only a small effect on the diffusion of the drug when compared with the diffusion curve of doxorubicin alone. Gelfoam or Avitene produced a thrombus-like consistency when added to a doxorubicin/Lipiodol combination, and an additional decrease in the doxorubicin appearance rate was observed. However, after 6 hours, doxorubicin levels for these mixtures reached control values observed in 3 hours. Angiostat without Lipiodol produced a profound concentration-dependent decrease in the diffusion of doxorubicin. After 9 hours, only 23% of the doxorubicin had been released. CONCLUSION: The strong complexing ability of the embolic agent Angiostat may enable it to be a carrier for doxorubicin and surpass other mixtures currently employed for transcatheter chemoembolization.

Detachable balloon occlusion of bronchopleural fistulae in dogs.

The use of detachable balloon occlusion in closure of bronchopleural fistulae was investigated in eight dogs. Fistula occlusion could not be achieved in one dog, and the balloon was not large enough to occlude a fistula in a second dog. Satisfactory fistula occlusion was achieved in the remaining six dogs. All fistulae occluded were shown to be satisfactorily healed at ten days. There were no significant sequelae to bronchial occlusion during this period. Detachable balloon occlusion of bronchopleural fistulae has the potential for satisfactory fistula control prior to more definitive surgery.

Problems in assessment of pulmonary parenchymal consolidation in heart transplant candidates.

Radiologic assessment of the cause of pulmonary parenchymal consolidation in end-stage heart failure may be difficult. From August 1982 to May 1989, 22 patients being considered for orthotopic cardiac allografts had parenchymal consolidation on their chest radiographs, most commonly in the right lower lobe. Our purpose was to determine from standard radiologic studies whether this consolidation represented alveolar pulmonary edema in an atypical basal distribution, pneumonia, or pulmonary infarction. This differentiation is important because pneumonia is an absolute and infarction is a relative contraindication to surgery, whereas successful transplantation can be performed in a setting of pulmonary edema. The chest radiographs were reviewed retrospectively. When available, pulmonary angiograms, nuclear medicine ventilation/perfusion scans, and needle biopsy findings were also evaluated. The radiologic assessment was correlated with the results of surgical, autopsy, or clinical outcome. None of the conventional modalities was very accurate--the plain chest film was correct in only 63%, nuclear medicine studies in 50%. Angiography was the single most useful test, with an accuracy of 75%.

Management of superior gluteal artery aneurysm by percutaneous balloon catheter occlusion: a case report.

A 19-year-old woman developed an aneurysm of the left superior gluteal artery following laparoscopy. Percutaneous insertion of a balloon catheter into the neck of the aneurysm for 48 hours resulted in permanent thrombosis of the aneurysm. Use of balloon catheters in the management of surgically inaccessible vascular lesions in discussed.

Duplex and color Doppler flow sonography of occlusion and near occlusion of the carotid artery.

PURPOSE: To determine whether color Doppler flow imaging with the use of slow-flow sensitivity improves sensitivity and specificity in the differentiation of occlusion and near occlusion of the internal carotid artery. METHODS: Color Doppler and duplex sonography were performed in symptomatic patients who had angiographically confirmed occlusion and/or near occlusion of the internal carotid artery. The study consisted of two phases: in the first, we assessed the usefulness of color Doppler flow imaging by retrospectively reviewing the records of 35 patients with 36 angiographically confirmed occlusions or near occlusions of the internal carotid artery who were examined with color Doppler flow imaging at our institution during a period of 4 years; in the second phase, we incorporated color Doppler sonography into the routine scanning protocols of 39 patients with 41 occluded or nearly occluded internal carotid arteries seen over a period of 2 1/2 years. RESULTS: Overall, color Doppler imaging correctly showed all 34 of the near occlusions (sensitivity, 100%) and 36 of the 43 occlusions (specificity, 84%). Seven patients with angiographically confirmed occlusion had sonographic findings that suggested near occlusion. In the first phase, eight near occlusions were misinterpreted as occlusions with conventional duplex sonography, but were correctly shown with color Doppler flow imaging. In the second phase, sensitivity increased from 50% to 100% (18 or 18) because of better detection of the nearly occluded lumen. This was at the expense of a decrease in specificity (from 100% to 78%). owing to identification of apparent flow in the internal carotid artery on color Doppler flow images in five of 23 occlusions. CONCLUSION: Because of its ability to depict slow flow, color Doppler imaging with slow-flow sensitivity is superior to conventional duplex sonography for the noninvasive discrimination of occlusion from near occlusion of the internal carotid artery.

Percutaneous gastrojejunostomy in amyotrophic lateral sclerosis.

We have performed a retrospective review of the use of a percutaneous gastrojejunostomy in patients with amyotrophic lateral sclerosis (ALS). Forty-one patients with initial bulbar manifestations of ALS and 32 patients with initial limb manifestations underwent a percutaneous gastrojejunostomy under fluoroscopic control using the Rankin gastrojejunostomy tube. Survival characteristics were compared with 86 bulbar onsetting and 207 limb onsetting ALS patients who did not require nutritional support. The 30-day mortality rate was 9.6% (respiratory death in three bulbar onsetting patients and four limb onsetting patients) and the 30 day morbidity rate was 4.1% (one operative site infection and intraperitoneal leakage in two patients). The most frequent long-term complication was the requirement for tube changing (blockage in six; dislodgment in two). Gastric reflux was not described amongst the treated patients. Overall survivorship (symptom onset to death) was less in the bulbar onsetting patients receiving a gastrojejunostomy tube than in the control population (median survival 22.0 vs. 33.7 months, respectively, P=0.005). As a group, the median survivorship for limb onsetting patients was not different for those receiving a gastrojejunostomy than for those who did not. However, a significant reduction in survival was observed in limb onsetting patients receiving a gastrojejunostomy early in the course of their disease (P=0.001) compared to those with a longer duration prior to the procedure. This was not observed in the bulbar onsetting patients. In both patient populations, no relationship was observed between survival post-gastrojejunostomy and the severity of pulmonary involvement at the time of the intervention, serum chloride, or age at onset. These studies demonstrate that a percutaneous gastrojejunostomy is a well-tolerated and safe alternative technique for enteral nutritional support in ALS patients. It also offers the advantage of not requiring either a general anaesthetic at the time of the procedure or instrumentation through the oropharynx. We have also observed that limb onsetting patients requiring a gastrojejunostomy early in the course of their illness are in a distinctive, less favorable, prognostic group.

A real vessel phantom for imaging experimentation.

Vascular phantoms are used to evaluate imaging techniques such as ultrasound (US), CT, and angiography. They are expected to mimic the vasculature, surrounding tissue, and blood, and therefore must meet specific requirements on the mimicking materials, with respect to x-ray attenuation and acoustic properties (velocity, attenuation). In the past, researchers have used a variety of vessel models, including walled (typically latex tube) and wall-less phantoms (obtained by moulding a lumen in a block of agar). These models lacked the exact geometry of human vessels as well as pathologic features such as plaques and calcifications. To overcome these disadvantages, this paper describes a real vessel phantom for US and x-ray studies. The phantom consists of an agar-filled acrylic box containing a formaldehyde fixed section of a real human vessel (obtained at autopsy) cannulated onto two acrylic tubes. This phantom was evaluated by comparing the images obtained with x-ray angiography, CT, and 3-D B-mode US. The images show good overall correlation based on the location of the geometrical features within the phantom, such as lumen, plaques, and calcifications. Discrepancies, artifacts, and difficulties were minor, and are discussed. The use of a real vessel, with its natural geometry and pathology, makes this phantom attractive for evaluation of imaging techniques including projection radiography, CT and US, and for extending its use to MR and US based flow studies.

Intravenous digital subtraction angiography and duplex ultrasonography in postoperative assessment of carotid endarterectomy.

Seventy-four consecutive patients who had undergone carotid endarterectomy procedures were examined with intravenous digital subtraction angiography (IV-DSA) and duplex ultrasonography (DUS) at intervals ranging from 1 to 14 months postoperatively. Ninety-one percent of the DUS and 74% of the DSA images were of diagnostic quality. The two modalities agreed in the assessment of the endarterectomy appearance in 84% of the arteries, with 85% showing no evidence of significant residual disease. There were no arteries with severe restenosis or complete occlusion. In the 10 vessels in which the two modalities disagreed in disease assessment, the IV-DSA images were often degraded by artifact or vessel overlap leading to underestimation of disease. The authors conclude that DUS is the examination of choice for routine follow-up studies of carotid endarterectomy.

Carotid transluminal angioplasty with evidence of distal embolization. Case report.

A 57-year-old woman presented with symptomatic triple tandem stenosis of the left carotid artery. Transluminal angioplasty of an atherosclerotic stenosis at the origin of the common carotid artery was performed retrogradely through a distal arteriotomy after endarterectomy. The postangioplasty effluent was collected and analyzed. Cholesterol crystals and amorphous plaque debris were identified, indicating a source for distal embolization. The clinical significance of this small amount of debris embolizing to the intracranial circulation is uncertain, but should be of concern when considering angioplasty of the cerebral circulation.

Deep-vein thrombosis and continuous passive motion after total knee arthroplasty.

Seventy-five of 150 consecutive patients who underwent total knee arthroplasty had routine physiotherapy and seventy-five had continuous passive motion of the lower limb that had been operated on as well as routine physiotherapy. A pulmonary embolus did not develop in any patient, but about 40 per cent had thrombosis in the veins of the calf, whether passive motion had been administered or not. Radiographically, the deep-vein thrombosis was seen to extend into or proximal to the popliteal vessel in 5 per cent of the patients in each group. Sex, age, obesity, or a history of hypertension or diabetes did not influence the incidence of venous thrombosis, but there was a higher incidence in patients in whom cement was used for fixation of the total knee components, irrespective of the use of continuous passive motion of the limb.

Elastic response of human iliac arteries in-vitro to balloon angioplasty using high-resolution CT.

Previous angioplasty studies have used angiography and intravascular ultrasound to obtain vascular dimensions. These imaging methods do not always provide reliable measurements due to limitations in image orientation and resolution. In this study, high-resolution (0.1 x 0.1 x 0.5 mm) transverse CT slices were obtained from human common-iliac arteries in vitro to study their elastic response pre- and post-angioplasty. Seven iliacs from five patients were imaged over the physiological pressure range both pre- and post-angioplasty. Contrast was obtained with humidified air surrounding the artery. Angioplasty was done with 10 or 12 mm diameter Medi-Tech balloon catheters with a balloon pressure of 300 kPa held for 30 s. Lumen circumference, c, measured from the images, was plotted against pressure, P, and curve fitting showed c = A(1 - e(-KP)) + B where A, K, and B are fitting parameters. Six lesions appeared soft and were compressed, while one was calcified and partially lifted off the wall. Normalized changes in parameters B and K were much higher post-angioplasty in the calcified lesion, and were over 3 standard deviations from the means of the normalized changes in the six compressed lesions. Balloon/stenosed lumen diameter ratios greater than 1.2 produced a lumen area increase of 38.6 +/- 4.1%(S.D.)(n = 3); ratios less than 1.2 produced an increase of 4.4 +/- 5.1%(S.D.)(n = 4). There was no correlation between area increase and balloon/normal lumen diameter ratio (the value used clinically). Arteries with lesions containing stiffer plaques that tear from the artery wall during angioplasty appear more distensible over the physiological pressure range post-angioplasty.

Rapid volume flow rate estimation using transverse colour Doppler imaging.

A system is described in which the volume flow rate of blood in a vessel is determined using transverse colour Doppler ultrasound imaging. The system measures rapidly the two-dimensional velocity profile of blood flowing through a vessel. By integration of the measured velocity profiles the volume flow rate of blood in the vessel is obtained. The Doppler angle is obtained from the included angle between two imaging planes, and their respective average measured flows. This technique yields instantaneous and average flow rate in real time, and permits long flow recordings to be made and stored digitally. The error is less than 5% over a 8:1 flow rate range.

Three-dimensional colour Doppler imaging.

We have developed a system to acquire in vivo three-dimensional (3D) colour velocity images of peripheral vasculature. A clinical ultrasound system was modified by mounting the transducer on a motor-driven translation stage, allowing planar ultrasound images to be acquired along a 37 mm long stroke. A 3D velocity image is acquired by digitizing, in synchrony with the cardiac cycle, successive video images as the transducer is moved over the skin surface. 3D images require about 1 min to acquire and 10 min to reconstruct before being viewed interactively. Image acquisition at several points in the cardiac cycle permits a cine-type reconstructed image. Geometrical, temporal and velocity accuracy of the acquisition and reconstruction have been quantified and found not to degrade the image.

Geometric characterization of stenosed human carotid arteries.

RATIONALE AND OBJECTIVES: The geometry of stenosed carotid bifurcations was analyzed to determine average representations for several stenosis grades. METHODS: Film angiograms of 62 patients with internal carotid artery stenoses were digitized. Residual lumen boundaries were manually outlined. The outlines were processed with a computer to extract geometric measurements. The measurements were grouped according to stenosis grade and used to create average representations. RESULTS: Accuracy and precision of the outlining technique were +/- 0.020 common carotid diameters (CCD) and +/- 0.025 CCD, respectively. Maximum narrowing of the internal carotid artery occurred at 0.3 CCD +/- 1.5 (mean +/- standard deviation) distal to the flow divider. The region of significant narrowing extended axially 1.2 CCD +/- 1.0. Poststenotic dilatations were observed, with enlargement of 1.3 +/- 0.7 times the normal diameter of the distal internal carotid artery. A tendency toward smaller bifurcation angles with increasing stenosis severity was observed. CONCLUSION: Three-dimensional geometric models could be created for carotid bifurcations that were disease free (normal) and of arbitrary stenosis grade.

Arteriovenous fistulas after replantation surgery.

The delayed appearance of congenital arteriovenous fistula precipitated by local trauma is a rare event. However, these reports may provide some insight into pathogenetic mechanisms responsible for the opening of subclinical arteriovenous communications. This case of multiple arteriovenous fistulas in a previously "normal" hand followed a sharp, incomplete amputation at the wrist level with replantation.

Gas formation after renal tumor embolization without abscess: a benign occurrence.

Gas formation was observed in the infarcted tissues of 2 patients after renal tumor embolization. There was no clinical evidence of abscess, which would have required special treatment, at the site of infarction. This is postulated to be part of the post-infarction syndrome, analogous to the appearance of gas in the fetal tissues after intra-uterine death.