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C B Higgins

Publications and source records attributed to C B Higgins.

At least 145 records · Page 8Linked to original sources
PubMed1993

Variation in left ventricular regional wall stress with cine magnetic resonance imaging: normal subjects versus dilated cardiomyopathy.

We measured the variation of end-systolic wall stress and its relation to regional ejection fraction in short-axis planes through the left ventricle in normal subjects and in patients with dilated cardiomyopathy (DCM) by cine magnetic resonance imaging. There was a gradual increase in end-systolic wall stress but a gradual decrease in ejection fraction from apex to base in normal subjects (14 +/- 6 to 52 +/- 15 kdyne/cm2, 78% +/- 12% to 62% +/- 8%) and in patients with DCM (49 +/- 28 to 130 +/- 30 kdyne/cm2, 40 +/- 18 to 23% +/- 9%). The end-systolic wall stress in patients with DCM was higher than in normal subjects at every level (p < 0.01). We conclude that there is a variation in end-systolic wall stress in both normal subjects and patients with DCM with regional ejection fraction inversely related to regional end-systolic wall stress.

Adult↗
PubMed1993

Use of nonionic or low osmolar contrast agents in cardiovascular procedures. American College of Cardiology Cardiovascular Imaging Committee.

Low osmolar contrast agents produce less adverse electrophysiologic and hemodynamic alterations during cardiac catheterization. The nonionic agents probably reduce the risk of provoking myocardial ischemia during coronary arteriography or ventriculography. Patients also report less subjective sensation of discomfort during administration of low osmolar agents for cardiovascular procedures. However, nonionic agents have not been proved to reduce the incidence of several serious complications of cardiac catheterization, including acute renal failure and anaphylactoid reaction. Although evidence is inconclusive, there may be an increased risk of thromboembolic complications during cardiac catheterization when certain low osmolar nonionic agents are administered. Nonionic contrast agents have not been definitely proved to reduce the risk of death after cardiac catheterization.

Cardiac Catheterization↗
PubMed1993

Magnetic resonance imaging and spectroscopy of the human heart.

Magnetic resonance imaging and spectroscopy have a great potential both for clinical cardiac diagnostics and for research in cardiac physiology, metabolism and disease. At the present time, cardiac MRI already is the method of choice in several clinical conditions, especially in imaging central vasculature and intra- and paracardiac masses. With the recent development of contrast agents and ability to measure both flow velocities and flow volume, the cardiac MRI is likely to have a profound role in evaluating coronary arterial disease as well as valvular heart disease. The limitations due to long imaging times of cardiac MRI-studies are likely to be overcome with the development of ultrafast imaging techniques in the near future. On the other hand, cardiac MRS is still a research tool, which needs technical improvements before it can be widely utilized in clinical work. However, attempts to this aim are highly justified, when the possibility that MRS will provide metabolic information of the heart is considered and bearing in mind, that MR-magnets with sufficient field strength for MRS are increasingly in use in most modern hospitals. The role of magnetic resonance imaging (MRI) and spectroscopy (MRS) in the evaluation of heart diseases is still evolving. Some clear indications for clinical use of cardiac MRI have already become apparent, whereas cardiac MRS is still confined to research applications. The current paper consists of a review of the role of MRI for cardiovascular diagnosis together with a review of the currents status of cardiac MRS.

Heart↗
PubMed1993

Cardiovascular responses after ionic and nonionic magnetic resonance contrast media in rats with acute myocardial infarction.

RATIONALE AND OBJECTIVES: Contrast media may have quantitatively or even qualitatively different effects in the presence of underlying pathologic states compared with normal states. This study was designed to examine and compare the hemodynamic effects of bolus administration of ionic (gadopentetate dimeglumine) and nonionic (gadodiamide) magnetic resonance (MR) contrast media in rats subjected to acute myocardial infarction. METHODS: Acute myocardial infarction was induced in two groups of rats (n = 20) by ligating the left coronary artery. Each animal received four bolus injections, iso-osmolar glucose followed by three incremental doses of either an ionic or a nonionic MR contrast agent (0.1, 0.3, and 0.5 mmol/kg). The effects of iso-osmolar glucose and each dose of MR contrast agent on the cardiovascular system were monitored for 15 minutes. RESULTS: Iso-osmolar glucose injection did not cause hemodynamic parameters to significantly differ from baseline values. Nonionic gadodiamide produced no significant hemodynamic effects at all injected doses compared with iso-osmolar glucose. However, ionic gadopentetate dimeglumine caused significant deleterious hemodynamic effects in a dose-dependent fashion. Gadopentetate dimeglumine caused depression in left ventricular (LV) systolic pressure and systemic arterial pressure at the lowest dose (0.1 mmol/kg). At the maximum dose (0.5 mmol/kg), gadopentetate dimeglumine decreased systolic arterial pressure by 48%, rate-pressure product by 55%, LV end systolic pressure by 48%, rate of rise of LV pressure (dP/dt) by 55%, and heart rate by 10%. LV end diastolic pressure increased by 46%. Arrhythmias were observed in 20% (2/10) of the animals after injection of gadopentetate dimeglumine, but not after gadodiamide. CONCLUSIONS: Compared with ionic gadopentetate dimeglumine, nonionic gadodiamide is a hemodynamically safe MR contrast agent in this experimental model when it is injected as a rapid bolus at high doses and in the presence of acute myocardial infarction.

Animals↗
PubMed1993

Effect of lidocaine on acute regional myocardial ischemia and reperfusion in the cat. An in-vivo 31P magnetic resonance spectroscopy study.

RATIONALE AND OBJECTIVES: The authors examined the relationship between myocardial infarction, high-energy phosphate compounds, and regional contractility after myocardial ischemia and reperfusion in cats. METHODS: Hemodynamic measurements, high-energy phosphate levels, and segmental shortening were measured every 30 minutes in two groups of cats subjected to 2 hours of occlusion of the left anterior descending coronary artery and 4 hours reperfusion. Group 1 (n = 10) animals were infused with a low level of lidocaine, 0.05 mg/kg/hr, while group 2 (n = 10) received a higher dose, 7.5 mg/kg/hr. The infarcted region was measured postmortem. RESULTS: Group 1 animals had larger infarcts (39 +/- 6 vs. 12 +/- 5% of jeopardy, P < .05) and less phosphocreatine recovery during reflow (52 +/- 7% vs. 73 +/- 2% of control, P < .01) than did group 2. Group 2 showed recovery of percentage systolic shortening during reflow (1.4 +/- 2% at 30 minutes vs. 7.1 +/- 2.3% at 4 hours, P < .05), whereas group 1 exhibited no improvement. A significant correlation was found between infarct size under the surface coil and phosphocreatine content during reflow, but not between contractile function and infarction size or metabolite levels during reflow. CONCLUSIONS: Lidocaine infusion enhanced recovery of myocardial contractility during reperfusion and decreased infarct size. Greater recovery of phosphocreatine during reperfusion was predictive of greater myocardial salvage during reperfusion.

Animals↗
PubMed1993

Comparison of T1-enhancing and magnetic susceptibility magnetic resonance contrast agents for demarcation of the jeopardy area in experimental myocardial infarction.

RATIONALE AND OBJECTIVES: This study compared the areas demarcated by a T1-enhancing agent, Gd-DTPA-BMA, and a magnetic susceptibility agent, Dy-DTPA-BMA, with 201thallium autoradiography (indicator of perfusion) and postmortem histochemical staining with triphenyltetrazolium chloride (TTC)(indicator of infarction). METHODS: Thirteen rats were subjected to coronary artery occlusion for 3 to 4 hours before acquisition of four sets of electrocardiogram-gated spin-echo magnetic resonance (MR) images: T1-weighted images before and after 0.2 mmol/kg Gd-DTPA-BMA; and T2-weighted images before and after 0.3 mmol/kg Dy-DTPA-BMA. After MR imaging, intravenous 201thallium delineated the area of decreased myocardial perfusion. At autopsy, TTC staining delineated the area of myocardial infarction. RESULTS: A myocardial region in the distribution of the occluded artery was delinated as a hyperintense area ("hot-spot") by Dy-DTPA-BMA and as a hypointense area ("cold-spot") by Gd-DTPA-BMA. The hyperintense area demarcated by Dy-DTPA-BMA (51 +/- 3% of the area of the midequitorial slice of the left ventricle) showed a closer relationship to the area of decreased myocardial perfusion (jeopardized area) (46 +/- 3%), determined by 201thallium autoradiography, than the area of myocardial infarction (36 +/- 4%), determined by histochemical staining. However, the hypointense area demarcated by Gd-DTPA-BMA (29 +/- 2%) did not relate as closely to the area of decreased myocardial perfusion (slope = 0.54) or the area of myocardial infarction (r = 0.46). CONCLUSIONS: The abnormal myocardial area delineated by the magnetic susceptibility agent showed a closer relationship to the area of deficient myocardial perfusion (jeopardy area) after coronary occlusion than that defined by T1-enhancing contrast media.

Animals↗
PubMed1993

Dual mechanisms for change in myocardial signal intensity by means of a single MR contrast medium: dependence on concentration and pulse sequence.

To determine whether gadodiamide injection can provide sufficient enhancement on both T1- and T2-weighted spin-echo magnetic resonance (MR) images of the heart and skeletal muscles, anesthetized rats were divided into five groups. Groups 1-3 received 0.1 (n = 9), 0.3 (n = 8), or 0.5 (n = 8) mmol/kg gadodiamide injection, respectively, and T1-weighted images were obtained. Groups 4 and 5 received 0.3 or 0.5 mmol/kg gadodiamide injection, respectively, and T2-weighted images were obtained. Gadolinium concentration was measured in myocardium by means of inductively coupled plasma-atomic emission spectroscopy. On T1-weighted images, the 0.1 and 0.3 mmol/kg doses produced a dose-dependent increase in myocardial signal intensity proportional to gadolinium concentration. A dose of 0.5 mmol/kg, which correlated with higher gadolinium concentration and did not further increase myocardial signal intensity, prolonged the imaging window. On T2-weighted images, the 0.3 mmol/kg dose caused a transient decrease in myocardial signal intensity; the 0.5 mmol/kg dose produced greater and persistent loss of signal intensity. In conclusion, the changes in signal intensity induced by gadodiamide injection depend on the dose, pulse sequence, and type of tissue.

Animals↗
PubMed1993

Echo-planar MR imaging of normal and ischemic myocardium with gadodiamide injection.

Rapid echo-planar (EP) magnetic resonance (MR) imaging was used to monitor the first pass of a bolus of gadodiamide injection in the hearts of normal rats and rats subjected to left coronary artery occlusion. Inversion-recovery EP imaging combined with a low dose (0.05 mmol/kg) of the contrast agent caused signal enhancement of normal myocardium from 19% +/- 4 to 63% +/- 5 (mean +/- 1 standard error of the mean) of fully relaxed intensity at the peak of the bolus but only slight increase in signal intensity of the ischemic zone. Thus, ischemic myocardium was demarcated as a hypointense zone (cold spot) during passage of the bolus. A higher dose (0.20 mmol/kg) of the same agent caused signal loss of normal myocardium from 100% to 39% +/- 7 of control at the peak of the bolus on gradient-recalled echo EP images, and ischemic myocardium was visualized as a hyperintense zone (hot spot). With either method of monitoring bolus transit, myocardial signal intensity recovered slowly following the peak bolus effect, consistent with substantial extraction of the agent during the first pass through the heart. Use of gadodiamide injection can allow discrimination between ischemic and nonischemic myocardium on both T1- and susceptibility-weighted EP images during bolus transit.

Animals↗
PubMed1993

Quantification of the left ventricular volumes and function with cine MR imaging: comparison of geometric models with three-dimensional data.

Acquisition and measurement of left ventricular (LV) volumes with a three-dimensional data set of cine magnetic resonance (MR) images from apex to base is a time-consuming process. Results of a study with 10 healthy volunteers and 10 patients with LV hypertrophy were prospectively evaluated. The heart was shown in the anatomic short- and horizontal long-axis planes with cine MR imaging. LV volumes were measured with various geometric models, and ejection fractions were calculated. In both groups, the values of LV stroke volume obtained with a modified Simpson rule and biplane ellipsoid models correlated well to the analysis of the three-dimensional data set of cine MR images. There were no significant differences for the calculated ejection fraction between values obtained with the modified Simpson rule or the biplane ellipsoid model versus the three-dimensional data set. A high inter-observer reproducibility of cine MR measurements with the two former models was found. Therefore, modified Simpson rule and biplane ellipsoid models, with their shorter acquisition and processing times, may increase the clinical utility of cine MR imaging.

Adult↗
PubMed1993

Evaluation of left ventricular volume and mass with breath-hold cine MR imaging.

Left ventricular (LV) volumes and mass were evaluated in 10 healthy volunteers with breath-hold cine magnetic resonance (MR) imaging. The results were compared with those obtained with conventional cine MR imaging. The breath-hold studies showed no ghosting artifact, and cardiac edges were clearly identified because of the reduced blurring. Measurements of LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), and LV mass obtained with breath-hold cine MR imaging showed close correlation with those obtained with conventional cine MR imaging (r = .98, .97, and .99, respectively). The interobserver variabilities for LVEDV, LVESV, and LV mass determined with breath-hold cine MR imaging (4.0%, 8.0%, and 3.7%, respectively) were equal to or less than those determined with conventional cine MR imaging (4.0%, 8.6%, and 5.0%, respectively). The authors conclude that breath-hold cine MR imaging is highly useful because an accurate assessment of cardiac function is obtained in less than 5 minutes.

Adult↗
PubMed1993

Localization of abnormal parathyroid glands of the mediastinum with MR imaging.

PURPOSE: To determine the sensitivity of magnetic resonance (MR) imaging for preoperative localization of abnormal parathyroid glands in the mediastinum and to compare the sensitivity of MR imaging with those of scintigraphy and ultrasonography (US). MATERIALS AND METHODS: The prospective sensitivity of MR imaging was compared with those of thallium-technetium scintigraphy and US in 25 patients in whom the abnormal gland was located in the mediastinum at surgery. RESULTS: MR imaging had a much higher sensitivity (22 of 25 cases [88%]) than did scintigraphy (11 of 19 cases [58%]) or US (three of 24 cases [12%]). The most common locations for the mediastinal gland were intrathymic (eight of 25 cases) and paraesophageal (six of 25 cases) sites. CONCLUSION: MR imaging should be considered the modality of choice for preoperative localization in this group of patients.

Adenoma↗
PubMed1993

Detection of abnormal parathyroid glands in postoperative patients with recurrent hyperparathyroidism: sensitivity of MR imaging.

OBJECTIVE: The efficacy of MR imaging in identifying abnormal parathyroid glands in patients with recurrent hyperparathyroidism after surgery was investigated. SUBJECTS AND METHODS: Findings on preoperative T1- and T2-weighted MR images in 44 patients with recurrent hyperparathyroidism were prospectively evaluated and compared with surgical/pathologic results in all patients. A blinded retrospective analysis of the MR findings comparing T1- or T2-weighted images alone and in combination for detection of abnormal parathyroid glands also was performed. RESULTS: Seventy-four percent of surgically proved abnormal parathyroid glands were detected prospectively and 65% were detected retrospectively on MR images. The combination of T1- and T2-weighted images increased the sensitivity for detection. The sensitivity for detection of abnormal glands was 72% in the neck and 86% in the mediastinum. The sensitivities for detecting parathyroid adenomas (80%) and hyperplastic glands (69%) were not significantly different. There was no threshold volume for detection of lesions with MR imaging. Both intrathyroid parathyroid adenomas were missed on MR images. Abnormal glands could not be differentiated from lymph nodes on MR images in three cases. CONCLUSION: MR imaging is a useful technique for detecting abnormal parathyroid glands preoperatively in patients with recurrent hyperparathyroidism after surgery. The combination of T1- and T2-weighted images increases the sensitivity for detection.

Adult↗
PubMed1993

MR imaging of the myocardium using nonionic contrast medium: signal-intensity changes in patients with subacute myocardial infarction.

OBJECTIVE: Gadodiamide injection (Omniscan, Sanofi Winthrop Pharmaceuticals, New York) is a new nonionic MR contrast medium that has been shown in animal studies to provide persistent differential enhancement of myocardial infarction. Because differential enhancement of normal and infarcted myocardium may be useful for the diagnosis and sizing of myocardial infarctions, we assessed the effectiveness of gadodiamide injection in enhancing signal-intensity differences between infarcted and normal myocardium on spin-echo T1-weighted images. SUBJECTS AND METHODS: Signal intensity of normal and infarcted myocardium, contrast ratio, contrast-to-noise ratio, and signal-to-noise ratio were measured in 12 patients with subacute myocardial infarction (mean, 16 days after diagnosis) before and after injection of contrast medium. Precontrast T1-weighted and T2-weighted images were obtained with a 1.5-T MR imager. T1-weighted images were acquired 5, 15, and 30 min after gadodiamide injection (0.2 mmol/kg) and T1-weighted images with fat saturation were acquired 10 min after gadodiamide injection. RESULTS: Gadodiamide injection significantly increased signal intensity of normal (34 +/- %) and infarcted (90 +/- %) myocardium compared with their signal intensities on precontrast T1-weighted images. The contrast ratio was significantly increased, and the augmented ratios persisted throughout the 45-min observation period. The contrast ratio on T2-weighted images was comparable to that on contrast-enhanced T1-weighted images (with or without the use of fat saturation). However, the signal-to-noise and contrast-to-noise ratios of T2-weighted images were significantly lower than those of contrast-enhanced T1-weighted images. The maximum contrast-to-noise ratio for visualizing myocardial infarction was achieved on contrast-enhanced T1-weighted images with fat saturation. CONCLUSION: Improved and persistent contrast between infarcted and normal myocardium can be produced on MR images by injecting gadodiamide at a dose of 0.2 mmol/kg, which provides prolonged delineation of myocardial infarctions. Maximum contrast-to-noise ratios for detecting myocardial infarction can be produced by using fat-saturated T1-weighted imaging after a high dose of this nonionic contrast medium has been administered.

Adult↗
PubMed1993

Role of MR imaging in acquired and congenital cardiovascular disease.

The use of MR imaging for noninvasive cardiac diagnosis is still limited because clinicians currently rely on echocardiography and nuclear scintigraphy. Because of the development of MR techniques that can be used to evaluate contractile function and blood flow as well as cardiac morphology, greater applications of MR imaging are now likely to occur. Such a multifaceted use of MR imaging for the evaluation of cardiovascular disease should be encouraged by the continued development of fast imaging techniques. The purpose of this review is to describe the current clinical applications of MR imaging in acquired and congenital heart disease. The widespread use of MR imaging for cardiovascular diagnosis ultimately depends on its suitability as a comprehensive noninvasive imaging technique for ischemic heart disease and as a replacement for cardiac catheterization in congenital heart disease.

Aortic Diseases↗
PubMed1993

Magnetic resonance angiography and blood flow quantification.

A variety of magnetic resonance (MR) techniques are available for flow imaging and quantification, each exploiting a different property of flowing blood to achieve contrast with stationary tissue, and each with its own strengths and limitations dependent on the flow conditions. These same techniques have been used to perform MR angiography of peripheral as well as the coronary arteries. This article provides an overview of MR angiographic and blood flow quantification techniques and their clinical application. Future technical advances in MR in concert with continuing developments in computer software and hardware are likely to make MR a major vascular technique in the coming decade.

Blood Flow Velocity↗
PubMed1993

Role of magnetic resonance imaging in hyperparathyroidism.

Magnetic resonance imaging is indicated for the localization of the abnormal gland or glands in patients with recurrent or persistent hyperparathyroidism. The accuracy of MRI is equivalent or superior to thallium subtraction scans and high-resolution ultrasonography for identifying the abnormal glands in the neck and superior to other noninvasive imaging techniques for recognizing ectopic glands in the thorax. Most glands have low to medium intensity on T1-weighted images and high intensity on T2-weighted images; however, glands with unusual signal intensity characteristics occur infrequently. Abnormal glands have shown considerable enhancement on T1-weighted images after use of gadolinium DTPA. Some pitfalls in the identification of abnormal parathyroid glands are now recognized.

Choristoma↗