Computed tomographic angiography for the evaluation of carotid artery stenosis

BACKGROUND AND PURPOSE: No previous study has compared the reliability of carotid artery measurement provided by axial images, shaded surface display (SSD), and maximum intensity projection (MIP). METHODS: Helical CT and conventional angiography were performed prospectively in 20 patients with atherosclerotic stenosis of the internal carotid artery. Stenosis measurement was performed in a blinded fashion on angiography and CT by two independent examiners. Calcifications were segmented when they were located far enough from the vascular lumen. SSD and MIP were systematically performed for each carotid bifurcation. We measured stenosis using conventional angiography as standard and the different CT reconstructions (axial images, SSD, and MIP) by comparing the stenosis diameter at its narrowest point to the normal internal carotid artery. The degree of stenosis was classified into six groups: no stenosis, mild stenosis (< 30%), moderate stenosis (30% to 70%), severe stenosis (> 70%), near occlusion, and occlusion (100%). No measurement was made in cases of normal artery, near occlusion, and occlusion. RESULTS: Correlations between angiography and the three types of reconstruction were very good. Axial sections correctly classified the carotid arteries in 95% of cases. In 10 carotid arteries, stenosis was not assessable by SSD and MIP because of calcifications. In the remaining carotid arteries, MIP correctly classified the degree of stenosis in 96% of cases, whereas SSD misclassified 21% of cases. CONCLUSIONS: Our study showed that axial images provide a reliable evaluation of carotid artery stenosis. Calcifications are limiting factors in SSD or MIP. When atherosclerotic plaques are not calcified, MIP reconstructions provide a more reliable measurement of the vascular lumen than SSD.     

Transradial approach for coronary procedures: initial experience and results

To characterize the myogenic response during the development of hypertension, we evaluated the myogenic response of small arteries isolated from the cremaster muscle of spontaneously hypertensive rats (SHR) aged 4-5 and 7-8 weeks, as compared with age-matched Wistar-Kyoto rats (WKY), using an in vitro system. The myogenic response of SHR aged 7-8 weeks (but not those aged 4-5 weeks) significantly exceeded that of WKY. Measurement of intracellular levels of free calcium ([Ca2+]i) in small arteries of the 7-8-week-old SHR and WKY loaded with a calcium-sensitive dye showed that the increase in [Ca2+]i in SHR was significantly greater than that in WKY during the myogenic response. The inhibitory effects of nitrendipine on the increased myogenic response and [Ca2+]i were greater in SHR. Thus, the myogenic response was enhanced in SHR and may be explained in part by an increase in Ca2+ entry through the voltage-dependent calcium channel (VDCC). The myogenic response and Ca2+ entry through the VDCC may be increased in association with the elevation of blood pressure.     

Computed tomographic angiographic imaging of abdominal aortic aneurysms: implications for transfemoral endovascular aneurysm management

Guinea pig pancreatic segments were superfused during 10 min with physiological saline solutions containing 10(-6) M acetylcholine (ACh) or histamine (10(-3)-10(-6) M) and the potassium concentration in the effluent [K+]o) was measured by flame photometry. Histamine evoked a transient increase in [K/]o. The removal of calcium from the superfusing solution and addition of 10(-4) M EGTA caused a significant reduction in the histamine-evoked potassium outflow. Replacement of chloride (Cl-) in the physiological salt solution by nitrate (NO3-) caused a significant reduction in the histamine-evoked potassium release. However, when Cl- was replaced by bromide (Br-) the response to histamine was unaffected. Pre-treatment of pancreatic segments with furosemide (10(-4 M) or ouabain (10(-3) M) caused a marked reduction in the histamine-induced potassium release. The results suggest that ionic requirements in histamine-evoked potassium release are the same as those in acetylcholine-evoked potassium efflux.     

Quinupristin/dalfopristin: spectrum of activity, pharmacokinetics, and initial clinical experience

In recent years, the prevalence of multiple drug-resistant strains of common Gram-positive pathogens has grown in many regions of the world. Increasingly, methicillin-resistant Staphylococcus aureus, coagulase-negative staphylococci, vancomycin-resistant enterococci, and penicillin-resistant pneumococci have been identified as causative organisms in serious and life-threatening infections. This increase in resistance highlights the need for new antimicrobial agents to expand the therapeutic armamentarium. Quinupristin/dalfopristin is the first of a unique class of antibiotics called streptogramins. It is characterized by a unique mechanism of action, intracellular activity, synergistic activity of its components, broad spectrum of activity against most Gram-positive cocci, common respiratory pathogens, and anaerobes, and demonstrated postantibiotic effect. Clinical evidence to date indicates that quinupristin/dalfopristin may be effective for the treatment of multidrug-resistant infections, especially those due to vancomycin-resistant enterococci and methicillin-resistant staphylococci. This article reviews the pharmacology, microbiology, and clinical experience with quinupristin/dalfopristin to date.     

Quantitative evaluation of a comprehensive motion, resolution, and attenuation correction program: initial experience

BACKGROUND: Tomographic myocardial imaging is widely used in the diagnosis and evaluation of patients with coronary artery disease. However, its specificity remains suboptimal because of attenuation, resolution, and motion artifacts. The purpose of this study was to optimize and assess the value of attenuation, blur, and motion correction of myocardial single photon emission computed tomographic data. METHODS AND RESULTS: Forty-seven studies were selected for analysis to provide 3 patient groups. Group A consisted of 18 patients with a low likelihood of coronary artery disease who were used to construct a quantitative normal database and assess changes in the normal bull's-eye produced by filtering and by attenuation correction. Group B consisted of 13 patients with a high probability of normal results, and group C consisted of 16 patients with coronary artery disease defined on angiography. The effects of attenuation correction, especially in conjunction with RESTORE (a depth-dependent deblurring filter), have been quantitated. Analysis indicates a trend to improved sensitivity and specificity for detecting individual vessel disease in this retrospective study. The motion correction program was successfully applied to 93% of patients but detected significant motion requiring correction in only 11 (24%) patients. CONCLUSION: This preliminary retrospective study indicates a potential for improved myocardial single photon emission computed tomography imaging with the use of attenuation and motion correction together with a restorative deblurring filter. Confirmation by a multicenter study and larger patient numbers remain necessary to assess fully the prospective value of the technique.     

Ultrasound evaluation of blunt abdominal trauma: program implementation, initial experience, and learning curve

OBJECTIVE: Although sonographic screening for blunt abdominal trauma is gaining acceptance, standards for implementation, training, credentialing, and quality control remain to be established. DESIGN: This prospective study examines a Level I trauma service experience with the de novo establishment of a trauma ultrasound (US) program credentialed through the Department of Surgery under the auspices of Continuous Quality Improvement. MATERIALS AND METHODS: All trauma surgeons attended a combined didactic and "hands on" 8-hour trauma US course. Abdominal sonography was subsequently performed on patients with potential blunt abdominal trauma followed by a standard diagnostic evaluation, which included computed tomographic scan, diagnostic peritoneal lavage, or observation. MEASUREMENTS AND MAIN RESULTS: Three hundred patients were studied over a 4-month period. They averaged 35 years of age with an average injury severity score of 12. The time required to perform the US examination averaged less than 3 minutes. Standard diagnostic evaluation included computed tomographic scan (21%), diagnostic peritoneal lavage (45%), and observation (34%). US examinations resulted in 277 true negatives, 17 true positives, two false positives, and four false negatives for a sensitivity of 81.0%, a specificity of 99.3%, and an accuracy of 98.0%. Annualized cost savings with the use of US evaluation versus standard diagnostic evaluation would amount to over $100,000.00. CONCLUSIONS: This experience with the de novo implementation of a trauma US program suggests that the training and credentialing requirements in this study are sufficient to provide surgeon ultrasonographers with acceptable competence in US diagnosis of blunt abdominal trauma.     

Computed axial tomographic scan measurement of abdominal fat distribution and its correlation with anthropometry and insulin secretion in healthy Asian Indians

Asian Indians have high insulin resistance, hyperinsulinemia, a high prevalence of diabetes, and a high waist to hip ratio (WHR), although the rate of obesity is low. WHR and visceral fat (VF) are highly correlated, and both are associated with insulin resistance. This study was performed to determine the normal ranges of abdominal fat distribution (subcutaneous [SF] and VF) in nondiabetic South Indians and also to study its correlations with WHR, plasma insulin, and metabolic profiles. Fat areas were measured by computed axial tomographic scan at the L4 to L5 level. Mean areas of SF and VF in men and women in this study were similar to the values in white populations. Women had significantly less VF than men. Gender differences were observed in the contribution of fat areas to anthropometric, hormonal, and metabolic variables. In general, in men, total fat (TF) area showed significant independent correlation with body mass index (BMI), WHR, and total cholesterol, and VF correlated with insulin secretion. In women, TF and BMI were correlated and SF showed a correlation with total cholesterol. Insulin secretion in women did not show a correlation with fat areas.     

Revascularization of the circumflex artery with mechanical stabilization: initial experience

OBJECTIVES: To evaluate the short-term result of the coronary artery revascularization without cardiopulmonary bypass for triple vessel disease, including the circumflex territory performed on the stabilized beating heart. METHODS: Prospective study conducted on the first 35 consecutive patients with triple vessel disease operated upon without cardiopulmonary bypass by a single surgeon (RC) at the Montreal Heart Institute between October 1996 and March 1997. RESULTS: Mean age of patients was 64 +/-1.6 years and the majority were men (30). Most common risk factors were hypercholesterolemia (65%) and familial history (55%) of ischemic heart disease. Main surgical indication was unstable angina (74%) and mean preoperative left ventricular ejection fraction was 53 +/- 3%. Hundred and twelve bypass were constructed averaging 3.2 +/- 0.1 grafts/patients of which 39 were made on branches of the circumflex artery. Average ischemic time was 34.17 +/- 2.17 minutes. The internal thoracic artery, saphenous vein, and radial artery were used as a vascular conduit in 44, 67, and 1 occasions respectively. There was one operative mortality, and one non Q perioperative myocardial infarction (CK-MB: 89 U/L). No patient required aortic counterpulsation balloon assistance. The average postoperative CK-MB (U/L) were 12.2 +/- 1.9, 15.2 +/- 3.2, and 10.3 +/- 1.7 at 1, 24 and 48 hours respectively. During the post-operative period 26% (9) of the patients presented atrial fibrillation, 6.5% (2) early reexploration for bleeding, and 63% (22) did not require transfusion. Average stay in hospital was 6.1 +/- 45 days. Coronary grafts were angiographically assessed in the first 10 patients and at the postmortem exam in one and displayed a 100% patency with 93.5% (29/31) adequate runoff. Conclusion: Triple vessel coronary artery disease revascularization is feasible on the beating heart without cardiopulmonary bypass with excellent short-term clinical and angiographic results.     

Computed tomographic grading is useful in the selection of patients for nonoperative management of blunt injury to the spleen

Although nonoperative management of blunt splenic injury (NMBSI) has an established role in the overall management of adult patients with blunt splenic injury, the criteria by which patients are selected continue to be debated. The purpose of this study is to establish the effectiveness of a defined set of criteria that includes CT grading for the selection of patients for NMBSI by examining the outcomes of patients managed in this manner 1 year before with those 1 year after the implementation of this specific set of selection criteria. All patients hospitalized at St. Joseph Mercy Hospital over the time period April 1994 through July 1996 with blunt splenic injury were included. Patients who died in the Emergency Department were excluded. Patients admitted from April 1994 through April 1995 composed Group I, those treated before the specific selection criteria, whereas those admitted from July 1995 through July 1996 composed Group II, those treated after the implementation of selection criteria. The two groups were compared with respect to demographic parameters, Injury Severity Score, mechanism of injury and length of stay. Outcomes were compared between these two groups. Those patients successfully managed without operation were further compared with those for whom NMBSI was unsuccessful. A total of 57 patients met the criteria for study entry, 28 from Group I and 29 from Group II. There were no significant differences between these two groups with respect to age, sex, mechanism of injury, Injury Severity Score, or length of stay. Nine of 27 in Group I required immediate operation; 19 were initially managed nonoperatively. Four of 19 required delayed laparotomy for bleeding, and all required splenectomy. Between patients successfully managed nonoperatively and those requiring delayed operation, the only significant difference was CT grade (1.47 vs 3.5; P = 0.0001). In Group II, after the implementation of selection criteria that included CT grade, no patient required delayed operation. Eleven underwent immediate operation, whereas 18 were successfully managed nonoperatively. We conclude that, in the hemodynamically stable patient without clinical indication for laparotomy, CT grading of the splenic injury is a reliable criterion by which patients may be selected for nonoperative management.     

Thoracoscopic upper thoracic sympathectomy for primary palmar hyperhidrosis--the combined paediatric, adolescents and adult experience

OBJECTIVE: To present our experience, over the past 4 years, of thoracoscopic upper thoracic sympathectomy in patients with primary palmar hyperhidrosis. DESIGN: Retrospective study. SETTING: University hospital, Israel. SUBJECTS: 402 thoracoscopic upper thoracic sympathectomies in 223 patients over a period of 4 years. INTERVENTIONS: Thoracoscopic ablation of ganglia and severing of the sympathetic chain at the level of T2 and T3. 142 patients underwent bilateral simultaneous sympathectomy, 37 had bilateral non-simultaneous sympathectomy and 44 had unilateral sympathectomy. RESULTS: 220 patients (98.7%) had an uneventful postoperative course and were discharged the following day. Three patients with residual pneumothorax required intercostal drainage and were discharged on the third postoperative day. 219 patients (98.2%) were completely satisfied, having immediate and permanent relief of palmar sweating. Four patients were dissatisfied. CONCLUSION: The thoracoscopic approach to the upper thoracic sympathectomy is at present the procedure of choice. Early operation for severe palmar hyperhidrosis is indicated to save a child many years of frustration and discomfort.     

Experience with computed tomographic angiography for the detection of intracranial aneurysms in the setting of acute subarachnoid hemorrhage

OBJECTIVE: To objectively compare computed tomographic angiography (CTA) with selective digital subtraction angiography (DSA) in the detection and anatomic definition of intracranial aneurysms, particularly in the setting of acute subarachnoid hemorrhage (SAH). METHODS: In a blinded prospective study, 40 patients with known or suspected intracranial saccular aneurysms underwent both CTA and DSA, including 32 consecutive patients with SAH in whom CTA was performed after CT images were obtained diagnostic for SAH. The CT angiograms were interpreted for presence, location, and size of the aneurysms, and anatomic features, such as the number of aneurysms lobes, aneurysm neck size (< or = 4 mm), and the number of adjacent arterial branches were suggested. The images obtained with CTA were then compared with the images obtained with DSA, with the later images serving as controls. RESULTS: DSA revealed 43 aneurysms in 30 patients and ruled out intracranial aneurysms in the remaining 10 patients. For aneurysm presence alone, the sensitivity and specificity for CTA was 86 and 90%, respectively. For the presence of an aneurysms, six CT angiogram showed false negative results and one CT angiogram showed a false positive result. False negative results were usually caused by technical problems with the image, tiny aneurysm domes (< 3 mm), and unusual aneurysm locations (i.e., intracavernous carotid or posterior inferior cerebellar artery aneurysms). The results obtained with CTA were, compared with the results obtained with DSA, more than 95% accurate in determining dome and neck size of aneurysm, aneurysm lobularity, and the presence and number of adjacent arterial branches. In addition, CTA provided a three-dimensional representation of the aneurysmal lesion, which was considered useful for surgical planning. CONCLUSION: CTA is useful for rapid and relatively noninvasive detection of aneurysms in common locations, and the anatomic information provided in images showing positive results is at least equivalent to that provided by DSA. In cases of SAH in which the nonaugmented CT and CTA results indicate a clear source of bleeding and provide adequate anatomic detail, we think it is possible to forego DSA before urgent early aneurysm surgery. In all other cases, DSA is indicated.     

Breath-hold gadolinium-enhanced MR angiography of the major vessels at 1.0 T: dose-response findings and angiographic correlation

PURPOSE: To find the appropriate contrast agent dose for gadolinium-enhanced magnetic resonance (MR) angiography by using individual measurement of contrast agent transit times in a randomized study. MATERIALS AND METHODS: A total of 34 patients with disease of the aorta or its major branches or both were randomly assigned to receive a dose of 0.1, 0.2, or 0.3 mmol of gadopentetate dimeglumine per kilogram of body weight. Initially, contrast agent transit times were measured with use of a turbo fast-low-angle-shot sequence. Subsequently, a three-dimensional fast imaging with steady-state precession sequence (7.3-msec repetition time, 2.8-msec echo time) was used for breath-hold MR angiography. Gadopentetate dimeglumine was injected with an MR-compatible power injector. Efficacy was evaluated by measurement of vessel enhancement and by clinical correlation of MR angiograms with x-ray angiograms. RESULTS: Evaluation of contrast agent transit time was possible in all patients with the test doses, which provided contrast-enhanced MR angiograms of constant quality. Neither vessel enhancement nor diagnostic information was significantly different across the these study groups. CONCLUSION: The clinical gadolinium dose of 0.1 mmol/kg is sufficient for diagnostic assessment of the aorta and its major branches at contrast-enhanced MR angiography. High-dose studies appear not to be required for these large vessels.     

Laparoscopic partial nephrectomy: initial experience and comparison to the open surgical approach

During an 18-month period, 6 laparoscopic partial nephrectomies were attempted, 4 of which were successful. The surgical technique was modified and improved between cases aided by new laparoscopic instrumentation, such as the argon beam coagulator and the 7.5 MHz. ultrasonic sector scanning system. In a retrospective comparison between laparoscopic and open partial nephrectomy, estimated blood loss was 525 ml. for the former versus 708 ml. for the latter procedure. However, operating time was more than 2 hours longer with the laparoscopic approach. The major advantages of the laparoscopic procedure appear to be a more rapid return to full diet, less postoperative pain and less requirement for parenteral narcotics. Despite the small size of this series and limited followup data, convalescence may be shortened by 4 weeks after laparoscopic partial nephrectomy. Patients with benign diseases of the kidney, especially with a duplicated collecting system, who require partial nephrectomy may be considered candidates for the laparoscopic approach. The advantages to the patient, however, may be offset by the technical demands on the surgeon.     

Computer-assisted intravenous anesthesia: value, method and use

To assess whether vomitoxin-induced dysregulation of IgA production and IgA nephropathy are reversible, relevant immunologic parameters were compared among experimental groups of B6C3F1 mice that were fed: (1) 25 ppm vomitoxin in AIN-76A semipurified diet for 24 weeks (treatment group), (2) 25 ppm vomitoxin for 8 weeks and then control diet for 16 weeks (withdrawal group), and (3) control diet for 24 weeks (control group). Levels of serum IgA and microhematuria index in the treatment group were elevated after 4 to 8 weeks and continued to increase with further vomitoxin exposure. IgA immune complexes and mesangial IgA deposition, as quantitated by interactive laser cytometer image analysis, were also increased with toxin exposure at Weeks 8, 16, and 24, whereas IgM, IgG, and complement component C3 deposition were unaffected or depressed. Serum IgA, microhematuria index, and mesangial IgA deposition in withdrawal mice remained elevated over those of the controls at Weeks 16 and 24 but were less than those of the treatment group. Cell recovery from Peyer's patches (PP) as well as the percentages of IgA+ and CD4+ cells in PP and spleen at Weeks 16 and 24 were greater in treatment mice than in controls, but only the percentage of IgA+ cells in PP was elevated in the withdrawal mice at these the same time points. When IgA secretion by unstimulated and LPS-stimulated splenic lymphocytes was used as the measure of systemic production, it was elevated in both treatment and withdrawal mice at Weeks 16 and 24. The results indicated that experimental dysregulation of IgA production and IgA nephropathy persisted up to 4 months after a discrete period of dietary vomitoxin exposure, but that the severity of these effects did not increase in a progressive fashion.     

Gadolinium-enhanced breath-hold three-dimensional time-of-flight MR angiography of the abdominal and pelvic vessels: the value of ultrafast MP-RAGE sequences

MR angiography (MRA) was performed in 50 consecutive subjects (mean age, 59 years), who had been referred for abdominal MRA, on a 1.5-T superconductive unit that used a body phased-array coil. Three breath-hold three-dimensional sequences were evaluated both in phantom and clinical studies: (a) standard fast three-dimensional gradient-echo sequence (TR = 15, TE = 6; imaging time, 32 seconds), (b) ultrafast three-dimensional gradient-echo sequence (TR = 8.2, TE = 3; imaging time, 18 seconds), and (c) ultrafast magnetization-prepared (MP) rapid acquisition gradient echo (RAGE) (TR = 5.8, TE = 2.9, inversion time [TI] = 20; imaging time, 15 seconds). The initial 30 patients were randomized into three groups by three separate sequences. For the remaining 20 patients, ultrafast-gradient-echo and ultrafast MP-RAGE sequences were performed. Conventional angiography was performed on 36 patients. Signal measurements of the phantom and clinical images of the aorta, visceral branches of the aorta, iliac arteries, inferior vena cavae, and portal veins were performed. The overall image quality and background fatty tissue contrast of the vessels were rated subjectively. Comparison of images between MRA and conventional angiography also was performed. The contrast between the vessels and background fatty tissue was significantly higher in the ultrafast MP-RAGE sequence in both quantitative and qualitative analysis, and image-quality ultrafast MP-RAGE was superior to the other two sequences (P < .01). The aorta and iliac arteries could be visualized in all pulse sequences, and abnormalities of these vessels were diagnosed correctly. The renal artery was visualized more clearly with the two ultrafast sequences.