Index MI Research Articles

Transcranial ultrasound angiography (tUSA): A new approach for contrast specific imaging of intracranial arteries

The goal was to develop an ultrasound contrast agent-specific imaging mode that offers an angiography-like view of the intracranial arteries and enables lower mechanical index MI settings compared to conventional transcranial duplex sonography. We studied 12 patients with transcranial ultrasound angiography (tUSA) via the temporal bone window after an IV bolus injection of a perfluorocarbon-based microbubble contrast agent (Imagent®). The aim was to display the intracranial vessel segments of the middle cerebral artery (M1, M2 and M3), the anterior cerebral artery (A1 and A2), the posterior cerebral artery (P1, P2 and P3) and the internal carotid artery (C1/2 and C3/4). tUSA is a B-mode phase inversion imaging technique that uses wideband harmonic signals for image generation. We demonstrate, in this report, that tUSA provides detailed anatomical display at native B-mode spatial resolution with fewer artifacts, yielding improved delineation of intracranial vessels that are in the 1- to 2-mm range. (E-mail: thoelscher@ucsd.edu)

Multiple Solutions and Its Morse Index for One-Dimensional Nonlinear Problem

The multiple solutions for one-dimensional cubic nonlinear problem u″ + u3 = 0, u(0) = u(π) = 0 are computed, on the basis of the eigenpairs of $$ - {\phi }\ifmmode{''}\else$''$\fi_{k} = \lambda _{k} \phi _{k} $$ , k = 1, 2, 3 · · ·. There exist two nonzero solutions ±u k corresponding to each k, and their Morse index MI(k) for 1 ≤ k ≤ 20 is to be exactly determined. It is shown by the numerical results that MI(k) ≥ k.

The clinical profile of patients with suspected cardiogenic shock due to predominant left ventricular failure: a report from the SHOCK Trial Registry

OBJECTIVESWe sought to evaluate the frequency of pulmonary congestion and associated clinical and hemodynamic findings in patients with suspected cardiogenic shock (CS).BACKGROUNDThe prevalence of pulmonary congestion in the setting of CS is uncertain.METHODSThe 571 SHOCK Trial Registry patients with predominant left ventricular failure (LVF) were divided into four groups: Group A = no pulmonary congestion/no hypoperfusion = 14 (3%), Group B = isolated pulmonary congestion = 32 (6%), Group C = isolated hypoperfusion = 158 (28%) and Group D = congestion with hypoperfusion = 367 (64%). Statistical comparisons between Group C and D only, with regard to patient demographics, hemodynamics, treatment and outcome, were made.RESULTSA significant proportion of patients with shock had no pulmonary congestion (Group C = 28%, 95% CI, 24% to 31%). Age and gender in this group were similar to Group D. Group C patients were less likely to have a prior MI (p = 0.028), congestive heart failure (p = 0.005) and renal insufficiency (p = 0.032), and the index MI was less likely to be anterior (p = 0.044). Cardiac output, cardiac index and ejection fraction were similar for the two groups but pulmonary capillary wedge pressure was slightly lower for Group C (22 vs. 24 mm Hg, p = 0.012). Treatment with thrombolysis, angioplasty and bypass surgery was similar in the two groups. In-hospital mortality rates for Groups C and D were 70% and 60%, respectively (p = 0.036). After adjustment, this difference was no longer statistically significant (p = 0.153).CONCLUSIONSAbsence of pulmonary congestion at initial clinical evaluation does not exclude a diagnosis of CS due to predominant LVF and is not associated with a better prognosis.

Cardiogenic shock due to acute severe mitral regurgitation complicating acute myocardial infarction: a report from the SHOCK Trial Registry

OBJECTIVESOur objective was to define the outcomes of patients with cardiogenic shock (CS) due to severe mitral regurgitation (MR) complicating acute myocardial infarction (AMI).BACKGROUNDMethods for early identification and optimal treatment of such patients have not been defined.METHODSThe SHOCK Trial Registry enrolled 1,190 patients with CS complicating AMI. We compared 1) the cohort with severe mitral regurgitation (MR, n = 98) to the cohort with predominant left ventricular failure (LVF, n = 879), and 2) the MR patients who underwent valve surgery (n = 43) to those who did not (n = 51).RESULTSShock developed early after MI in both the MR (median 12.8 h) and LVF (median 6.2 h) cohorts. The MR patients were more often female (52% vs. 37%, p = 0.004) and less likely to have ST elevation at shock diagnosis (41% vs. 63%, p < 0.001). The MR index MI was more frequently inferior (55% vs. 44%, p = 0.039) or posterior (32% vs. 17%, p = 0.002) than that of LVF and much less frequently anterior (34% vs. 59%, p < 0.001). Despite having higher mean LVEF (0.37 vs. 0.30, p = 0.001) the MR cohort had similar in-hospital mortality (55% vs. 61%, p = 0.277). The majority of MR patients did not undergo mitral valve surgery. Those undergoing surgery exhibited higher mean LVEF than those not undergoing surgery; nevertheless, 39% died in hospital.CONCLUSIONSThe data highlight opportunities for early identification and intervention to potentially decrease the devastating mortality and morbidity of severe post-myocardial infarction MR.

Assessing Structure of Aged Natural Sedimentary Clays

Soils become stiffer as they age. In this paper, attempts were made to assess the in-situ structure of natural clays by calculating the current quasi-elastic shear modulus from shear wave velocity measurement, Gmax. The Gmax value of reconstituted clays was employed as a yardstick against which the corresponding characteristic of natural sedimentary clays is examined, implying that the intrinsic properties of a non-aged reconstituted clay provide a basic frame of reference for assessing the in-situ structure of a natural clay and the influence of ageing (secondary compression and interparticle bondings) on its in-situ properties. In a series of bender element (BE) tests on a reconstituted clay, it was first manifested that the relationship between the void ratio and Gmax as subjected to one-dimensional compression exhibited the state boundary (SB) curve applicable to the short-term migration of effective stress. Second, it was demonstrated that the SB curve was violated when the clay aged by drained creep, and that the state of the aged clay rejoined the SB curve in a gradual manner on subsequent stressing applied over a short period. In the light of this characteristic time-dependent behaviour of Gmax, a measure termed metastability index MI (Gmax) has been newly proposed for assessing the structuration/destructuration of in-situ natural sedimentary clays which undergo effects of a long-term insitu ageing. The performance of MI (Gmax), together with the non-dimensional soil constant reflecting structure, S (Jamiolkowski et al., 1994), was carefully examined in the BE tests using various natural and reconstituted clays. It was successfully demonstrated that : i) the proposed index MI (Gmax) as well as the S-value were both equally capable of expressing structuration/destructuration of clays as examined in tests on Ariake (Japan), Bangkok (Thailand) and Louiseville (Canada) clays, each comprising a pair of a natural and its reconstituted sample ; ii) two different formations of soil structure, i.e., an on-depositional structure formed at sedimentation and the evolving post-depositional structure enriched due to ageing, should both be addressed for a proper understanding of the current structure of natural clays ; iii) the S values were similar among a total of nine non-aged reconstituted clays, despite a wide spread of plasticity index as well as compresssibility ; and iv) the S-value of each reconstituted clay is the lower bound against which the in-situ structure of the natural clay can be quantified at the relevant effective stress. A time-dependent soil structuration was also predicted by introducing a soil constant for metastabilization, Cβ.

Case Studies of In-Situ Structure of Natural Sedimentary Clays

ABSTRACT Natural sedimentary clays exhibit ageing effects on their behaviour when subjected to both consolidation and shearing. Attempts to characterising the in-situ ‘structure’ of soft marine clays have been made in case studies performed in Ariake (Japan) and in Bangkok (Thailand), each showing a typical profile of aged clay-structure with depth reflecting its site-specific geological consolidation history. In each site, profiles of Atterberg limits, natural water content, overconsolidation ratio (OCR), quasi-elastic shear modulus Gmax and the undrained shear strength cu with depth were attained from various laboratory tests, together with the a comparable profile of quasi-elastic shear modulus from in-situ seismic survey Gf. Quantitative assessment of the aged clay-structure was made by using two different measures, metastability index MI(G) and the soil constant reflecting structure S (Jamiolkowski et al., 1994). The profiles of MI(G) and the S-value with depth were both determined based on the corresponding Gmax behaviour of the reconstituted sample. “Disturbance” of laboratory samples retrieved by using two different samplers (i.e., Laval and Japanese thin-walled samplers) with two different sampling techniques (i.e., pre-boring and displacement methods) was discussed. A new approach to estimate cu “in the ground”, termed by the authors the MILK (Metastability Index coupled with Laboratory K0 test) method, is proposed. A trial of the MILK-method is demonstrated in soft Bangkok clay, the texture of which is similar to “soft cheese”.

Experimental Inactivated Concentrated Adjuvant Rabies Vaccine. Evaluation of its Efficacy in Cattle

Experimental Inactivated Concentrated Adjuvant Rabies Vaccine. Evaluation of its Efficacy in Cattle

1023-111 Effects of Propranolol in Patients with Their First Acute Myocardial Infarction and Persistent Electrocardiographic ST Segment Depression in the Beta Blocker Heart Attack Trial

The available data suggest that patients (pts) recovering from an acute my ocardial infarction (AMI) who have persistent electrocardiographic (ECG) ST segment depression (STD) are at high risk for future cardiac events when compared with AMI pts without STD. There are little data on the long term effects of medical therapy on acute MI pts with STD. The objectives of this retrospective analysis were to examine in the Beta Blocker Heart Attack Trial (BHAT) the effects of propranolol in this high risk group. Of the 2877 first MI BHAT pts, 656 pts had persistent ECG STD from the time of admission until randomization (9.7 ± 3.1 days after index MI). Of these, 317 pts were randomized to the propranolol and 339 pts to placebo. There were no significant baseline differences (p &lt; 0.05) between the two groups. The median follow up was 24.6 months. Follow-up Events Propranolol Placebo p-value (n = 317) (n = 339) (Cox regression) Overall mortality 7.6% 13.6% 00078 Sudden death 4.7% 9.7% 00094 Definite or probable MI 3.8% 7.7% 0.037 MI andlor mortality 9.2% 17.4% 0.0011 Cox regression analysis, adjusting for baseline variables showed the relative risk of mortality and the relative risk of sudden death were 2.13 (1.22, 3.70) and 2.56 (1.27, 5.26) respectively in the placebo, compared to the propranolol group. It appears that propranolol therapy is effective in reducing cardiac events in pts recovering from an AMI with ECG STD.

Presentation and late outcome of myocardial infarction in the absence of angiographically significant coronary artery disease

To determine the natural history of myocardial infarction (Ml) in the absence of angiographically significant (no lesion ≥ 50% diameter stenosis) fixed coronary artery disease (CAD), clinical and angiographic data and late outcome were studied in 43 such patients. The mean age was 45 ± 11 years; 32 patients (74%) were cigarette smokers. Mild fixed CAD, present in 38 patients (88%), was more frequent in the artery supplying the MI zone (p < 0.01). Filling defects or serial angiographic resolution of obstruction in the artery supplying the MI zone were present in 14 patients (33%). At late follow-up, 14 major cardiac events occurred in 9 patients, including revascularization in 3, recurrent MI in 6 and cardiac death in 5. Of 35 patients undergoing catheterization within 1 year of the index MI, cumulative risk of a major cardiac event was 9 ± 4, 12 ± 5 and 20 ± 7% at 3, 19 and 37 months, respectively. Myocardial infarction in the absence of significant fixed CAD tends to occur in young smokers with mild CAD in the artery serving the MI zone. Superimposed intracoronary thrombus can be frequently implicated. In these patients, subsequent major cardiac events may occur more frequently than previously reported.

Dimensions of verbal denial in myocardial infarction. Correlates to 3 denial scales.

The concept of denial in medical patients was reviewed, and problems in the past research on denial was noted. A questionnaire developed to assess different aspects of denial in myocardial infarction was tested in a group of 367 patients. A factor analysis of the questionnaire gave 3 independent factors, termed Denial of Illness, Denial of Impact, and Suppression. This finding gave support to the model that guided the construction of the questionnaire, and also casted some doubt on the validity of using either single specific or global criteria in assessing denial. Multiple regression analyses, including a series of medical, psychological and social variables, showed that social desirablity and external health locus of control contributed to the prediction of high scores on all 3 scales. Denial of Illness was furthermore associatd with less previous cardiac disease and a less severe index MI, whereas Denial of Impact was related to indicators of more optimistic attitudes. Suppression was related to indicators of lower socio‐economic status and less cardiac health knowledge. The 3 scales should be further examined in relation to outcome after a myocardial infarction.

Inhibition of human leukocyte migration in agarose by kcl extracts of carcinoma of the lung.

The leukocyte migration in agarose assay recently developed by Clausen (Clausen, 1971), was used to test 22 lung cancer patients against soluble extracts of allogeneic lung cancer and allogeneic normal lung. Seventeen were inhibited to a significantly greater degree by at least one tumor extract (average migration index (MI equals 0.58) than by the corresponding normal lung extract (average MI equals 0.83). DNCB-positive and DNCB-negative patients reacted with equal frequency to tumor extracts. Three patients tested against their autologous tumor and normal lung extracts were specifically inhibited by the tumor extract (average MI equals 0.53) but not by the normal lung extract (average MI equals 0.83). None of seven lung cancer patients tested against non-pulmonary tumor extracts was significantly inhibited (average MI equals 1.1). Only 6/53 controls including patients with other tumors, patients with emphysema and age-matched non-smokers showed significant inhibition against any of the lung cancer extracts. These findings strongly suggest the presence of tumor-associated antigens in KCl-solubilized extracts of human lung cancer.

A non-linearly processed array for enhanced azimuthal resolution: Institute of Electrical and Electronics Engineers Transactions on Sonics and Ultrasonics, Vol SU-15, No 4 (October 1968) PP 202–208

Nitric oxide (NO) has been implicated in smooth muscle relaxation. Its use has been widespread in cardiology. Due to the effective scavenging of NO by hemoglobin, however, the drug has to be applied locally or in large quantities, to have the effect desired. We propose the use of encapsulated microbubbles that act as a vehicle to carry the gas to a region of interest. By applying a burst of high-amplitude ultrasound, the shell encapsulating the gas can be cracked. Consequently, the gas is released upon which its dissolution and diffusion begins. This process is generally referred to as (ultra)sonic cracking.To test if the quantities of released gas are high enough to allow for NO-delivery in small vessels (ø < 200 μm), we analyzed high-speed optical recordings of insonified stiff-shelled microbubbles. These microbubbles were subjected to ultrasonic cracking using 0.5 or 1.7 MHz ultrasound with mechanical index MI > 0.6. The mean quantity released from a single microbubble is 1.7 fmol. This is already more than the NO production of a 1 mm long vessel with a 50 μm diameter during 100 ms. However, we simulated that the dissolution time of typical released NO microbubbles is equal to the half-life time of NO in whole blood due to scavenging by hemoglobin (1.8 ms), but much smaller than the extravascular half-life time of NO (>90 ms).We conclude that ultrasonic cracking can only be a successful means for nitric oxide delivery, if the gas is released in or near the red blood cell-free plasma next to the endothelium. A complicating factor in the in vivo situation is the variation in blood pressure. Although our simulations and acoustic measurements demonstrate that the dissolution speed of free gas increases with the hydrostatic pressure, the in vitro acoustic amplitudes suggest that the number of released microbubbles decreases at higher hydrostatic pressures. This indicates that ultrasonic cracking mostly occurs during the expansion phase.

Effects of dislocation motion on the ultrasonic attenuation in potassium and gold at low temperatures: Journal of Applied Physics Vol 39, No 6 (May 1968) pp 2744–2746

Nitric oxide (NO) has been implicated in smooth muscle relaxation. Its use has been widespread in cardiology. Due to the effective scavenging of NO by hemoglobin, however, the drug has to be applied locally or in large quantities, to have the effect desired. We propose the use of encapsulated microbubbles that act as a vehicle to carry the gas to a region of interest. By applying a burst of high-amplitude ultrasound, the shell encapsulating the gas can be cracked. Consequently, the gas is released upon which its dissolution and diffusion begins. This process is generally referred to as (ultra)sonic cracking.To test if the quantities of released gas are high enough to allow for NO-delivery in small vessels (ø < 200 μm), we analyzed high-speed optical recordings of insonified stiff-shelled microbubbles. These microbubbles were subjected to ultrasonic cracking using 0.5 or 1.7 MHz ultrasound with mechanical index MI > 0.6. The mean quantity released from a single microbubble is 1.7 fmol. This is already more than the NO production of a 1 mm long vessel with a 50 μm diameter during 100 ms. However, we simulated that the dissolution time of typical released NO microbubbles is equal to the half-life time of NO in whole blood due to scavenging by hemoglobin (1.8 ms), but much smaller than the extravascular half-life time of NO (>90 ms).We conclude that ultrasonic cracking can only be a successful means for nitric oxide delivery, if the gas is released in or near the red blood cell-free plasma next to the endothelium. A complicating factor in the in vivo situation is the variation in blood pressure. Although our simulations and acoustic measurements demonstrate that the dissolution speed of free gas increases with the hydrostatic pressure, the in vitro acoustic amplitudes suggest that the number of released microbubbles decreases at higher hydrostatic pressures. This indicates that ultrasonic cracking mostly occurs during the expansion phase.

Techniques of ultrasonic paramagnetic resonance: The Review of Scientific Instruments, Vol 39, No 10 (October 1968)

Nitric oxide (NO) has been implicated in smooth muscle relaxation. Its use has been widespread in cardiology. Due to the effective scavenging of NO by hemoglobin, however, the drug has to be applied locally or in large quantities, to have the effect desired. We propose the use of encapsulated microbubbles that act as a vehicle to carry the gas to a region of interest. By applying a burst of high-amplitude ultrasound, the shell encapsulating the gas can be cracked. Consequently, the gas is released upon which its dissolution and diffusion begins. This process is generally referred to as (ultra)sonic cracking.To test if the quantities of released gas are high enough to allow for NO-delivery in small vessels (ø < 200 μm), we analyzed high-speed optical recordings of insonified stiff-shelled microbubbles. These microbubbles were subjected to ultrasonic cracking using 0.5 or 1.7 MHz ultrasound with mechanical index MI > 0.6. The mean quantity released from a single microbubble is 1.7 fmol. This is already more than the NO production of a 1 mm long vessel with a 50 μm diameter during 100 ms. However, we simulated that the dissolution time of typical released NO microbubbles is equal to the half-life time of NO in whole blood due to scavenging by hemoglobin (1.8 ms), but much smaller than the extravascular half-life time of NO (>90 ms).We conclude that ultrasonic cracking can only be a successful means for nitric oxide delivery, if the gas is released in or near the red blood cell-free plasma next to the endothelium. A complicating factor in the in vivo situation is the variation in blood pressure. Although our simulations and acoustic measurements demonstrate that the dissolution speed of free gas increases with the hydrostatic pressure, the in vitro acoustic amplitudes suggest that the number of released microbubbles decreases at higher hydrostatic pressures. This indicates that ultrasonic cracking mostly occurs during the expansion phase.

Measurement E.A.: Institute of Electrical and Electronics Transactions on Sonics and Ultrasonics, Vol SU-15, No 2 (April 1968) pp 81–88

Nitric oxide (NO) has been implicated in smooth muscle relaxation. Its use has been widespread in cardiology. Due to the effective scavenging of NO by hemoglobin, however, the drug has to be applied locally or in large quantities, to have the effect desired. We propose the use of encapsulated microbubbles that act as a vehicle to carry the gas to a region of interest. By applying a burst of high-amplitude ultrasound, the shell encapsulating the gas can be cracked. Consequently, the gas is released upon which its dissolution and diffusion begins. This process is generally referred to as (ultra)sonic cracking.To test if the quantities of released gas are high enough to allow for NO-delivery in small vessels (ø < 200 μm), we analyzed high-speed optical recordings of insonified stiff-shelled microbubbles. These microbubbles were subjected to ultrasonic cracking using 0.5 or 1.7 MHz ultrasound with mechanical index MI > 0.6. The mean quantity released from a single microbubble is 1.7 fmol. This is already more than the NO production of a 1 mm long vessel with a 50 μm diameter during 100 ms. However, we simulated that the dissolution time of typical released NO microbubbles is equal to the half-life time of NO in whole blood due to scavenging by hemoglobin (1.8 ms), but much smaller than the extravascular half-life time of NO (>90 ms).We conclude that ultrasonic cracking can only be a successful means for nitric oxide delivery, if the gas is released in or near the red blood cell-free plasma next to the endothelium. A complicating factor in the in vivo situation is the variation in blood pressure. Although our simulations and acoustic measurements demonstrate that the dissolution speed of free gas increases with the hydrostatic pressure, the in vitro acoustic amplitudes suggest that the number of released microbubbles decreases at higher hydrostatic pressures. This indicates that ultrasonic cracking mostly occurs during the expansion phase.