Biomedical subjects

A D Lim

Publications and source records attributed to A D Lim.

8 recordsLinked to original sources

PubMed1995

Feasibility of Meckel's scan after RBC gastrointestinal bleeding study using in-vitro labeling technique.

The authors report a successful Meckel's scan performed 26 hours after a labeled RBC study using a commercial in-vitro labeling kit, UltraTag (Mallinckrodt Medical, Inc., St. Louis, MO). No abnormal alteration of Tc-99m distribution was observed as would be seen if an in-vivo RBC labeling technique was used. This case demonstrates that it is feasible to perform an in-vitro labeled RBC study for acute gastrointestinal bleeding in pediatric patients and to follow-up with a Meckel's scan if it is necessary for diagnostic confirmation.

Child↗

PubMed1994

Technetium-99m-MDP uptake in thyroid cartilage in invasive squamous-cell laryngeal carcinoma.

A 36-yr-old male with a past history of invasive squamous-cell carcinoma of the larynx underwent 99mTc-MDP scintigraphy for the evaluation of lower back pain. The scan findings were unremarkable except for markedly and uniformly increased tracer uptake in the region of the thyroid cartilage, suggesting calcification and/or tumor invasion. Confirmation of significant pathology was obtained on tissue examination from a subsequent total laryngectomy demonstrating inflammatory infiltration and perichondrial invasion of the thyroid cartilage by carcinoma.

Adult↗

PubMed1994

A count-based radionuclide method for volume quantitation using conjugate imaging and an external reference source: theoretical consideration and phantom study.

UNLABELLED: A count-based method was developed for ventricular volume determination during multigated equilibrium cardiac blood-pool imaging (MUGA). METHODS: Two sets of conjugate images of the volume were obtained, one with an external reference overlying the volume and the other without. The reference has known activity and dimension. The ratio of the geometric mean count rates over a pixel obtained from these two conjugate images, Ratio(geo), and the ratio of the specific activity in the reference to that in the volume, Ratio(ext), were used to calculate the length of the volume over that pixel perpendicular to the camera face, H, as a function of the length of the reference source, R, and the attenuation coefficient, ub, of the volume: [formula: see text] Based on H, the volume is then calculated. This method corrects for attenuation directly and determines the volume explicitly. To validate this method, phantom studies are carried out with known volumes of 99mTc containing saline solutions in situations of variable amount of attenuating medium and background activity. RESULTS: In all cases, the calculated volume agrees closely with the actual volume. CONCLUSION: This is an accurate method of volume quantitation that is well suited for determining ventricular volume during MUGA studies.

Cardiac Volume↗

PubMed1992

Tc-99m sestamibi myocardial imaging at rest for evaluation of cocaine-induced myocardial ischemia and infarction.

Many clinical cases of cocaine-induced myocardial infarction have been reported in the literature. Of the reported cases, patients tend to be young (in the third decade of life), chronic abusers with myocardial infarction typically involving the anterior left ventricular wall. This case report demonstrates the usefulness of two-phase (symptomatic and asymptomatic) Tc-99m sestamibi myocardial imaging at rest for definitive diagnosis of cocaine-induced myocardial ischemia and infarction.

Adult↗

PubMed1991

Dipyridamole perfusion scintigraphy: the experience with its application in one hundred seventy patients with known or suspected unstable angina.

We evaluated the safety, accuracy, and potential clinical utility of intravenous dipyridamole perfusion scintigraphy with thallium-201 in 170 patients, 78 with suspected and 92 with known unstable angina. All had coronary angiography. Noncardiac side effects (26%), induced chest discomfort (44%), and ST segment changes (12%) were similar in the two groups. No significant arrhythmias occurred. Two patients had prolonged chest pain, both with extensive reversible image abnormalities and associated creatinine kinase-MB release. Both had elective bypass surgery. Twenty-eight patients had normal coronary arteries, and 35 had single-vessel disease. Scintigraphic per patient sensitivity and specificity were 91% and 79% with a per vessel sensitivity of 74% and a per vessel specificity of 78% without between-group differences. During a brief follow-up period, 62 patients with image abnormalities had coronary revascularization, and there were seven deaths without intergroup differences. In a similar patient group that did not have angiography, scintigraphic defects were less frequent and less extensive, revascularization was not performed, and subsequent deaths occurred less often. Dipyridamole perfusion scintigraphy is an accurate alternative to exercise testing in the evaluation of patients with unstable angina pectoris. Although not without risk, the method appears relatively safe and should be considered as a guide to diagnosis, and probably to prognosis and management.

Adult↗

PubMed1990

Independence of intrapericardial right and left ventricular performance in septic pulmonary hypertension.

To study the effect of septic pulmonary hypertension on right/left ventricular intrapericardial interactions thirteen trauma patients, seven septic and six non-septic controls, were compared. Ventricular volumes were derived from first-pass or gated equilibrium radionuclide angiocardiography, and related to body surface area. Systemic and pulmonary pressures were measured invasively. Pulmonary arterial pressure was significantly increased in the sepsis group. Although right ventricular end-diastolic volumes were higher in sepsis, left ventricular end-diastolic volumes were not decreased. In terms of intrapericardial right/left ventricular interactions these results indicate that the right and left ventricles operate independently in septic pulmonary hypertension.

Adult↗

PubMed1988

Segmental evaluation of left ventricular wall motion after myocardial infarction: magnetic resonance imaging versus echocardiography.

To assess relative capabilities of magnetic resonance (MR) imaging and two-dimensional echocardiography (2DE) for evaluating regional contractile dysfunction in the left ventricle after a myocardial infarction, results from 22 concurrent MR (orthogonal-transaxial, ECG-gated, multiphasic, single-spin echo) and 2DE examinations were compared. By means of the same 11-segment LV description, MR and 2DE examinations were independently scored segment by segment for residual wall motion (point scores: 2 = normal, 1 = hypokinesia, 0 = akinesia, and -1 = dyskinesia). Significant correlation between MR and 2DE scoring was found throughout most of the left anterior descending (LAD) distribution, but right coronary artery (RCA) distribution (i.e., middle-posterior segment not well seen) could not be fully evaluated by MR imaging. When cumulative scores for the 10 segments mutually evaluated were used to derive measures of global residual LV function (i.e., score quotient [SQ] = accumulated points divided by 20 total possible points), MR SQ correlated well overall with both 2DE SQ (r = 0.82; p less than 0.05) and ejection fraction (EF) from ventriculography (r = 0.86, p less than 0.05 vs r = 0.88, p less than 0.05 for 2DE SQ compared with EF). MR evaluation of segmental wall motion was relatively stronger in the LAD distribution (MR SQ compared with 2DE SQ: r = 0.86, p less than 0.05; MR SQ compared with EF: r = 0.96, p less than 0.05) than in the RCA distribution (r = 0.06, p greater than or equal to 0.05 and r = 0.62, p greater than or equal to 0.05, respectively). For 2DE, regional variations were not as evident (2DE SQ compared with EF: r = 0.90, p less than 0.05 for LAD and r = 0.81, p less than 0.05 for RCA). For segmental evaluation of wall motion after myocardial infarction, MR imaging (transaxial, multiphasic) appears to be comparable to 2DE overall but superior in LAD distribution and inferior in RCA distribution.

Adult↗

PubMed1988

Estimation of the functional and anatomic extent of myocardial infarction using magnetic resonance imaging.

This study assesses magnetic resonance (MR) imaging for the evaluation of both the functional and anatomic extent of damage to the left ventricle (LV) from myocardial infarction (MI). This was accomplished by blinded region-of-interest analysis of 36 MR examinations (orthogonal-transaxial, electrocardiographically-gated, multiphasic, single spin-echo) for determination of ejection fraction (EF) and relative MI volume (i.e., percent of total LV myocardial volume). Comparison of the results was then made with a measure of global residual LV function (i.e., score quotient or SQ) derived from segmental scoring of LV wall motion on a two-dimensional echocardiogram (Echo) and with an EF value from a left ventriculogram (LVG), both performed relatively concurrently with MR. Significant (p less than 0.01) overall correlations were noted between MR-EF and both Echo-SQ (r = 0.56) and LVG-EF (r = 0.78), and these relationships were relatively stronger when MI was located in the right coronary artery (RCA) than when it was found in the left anterior descending (LAD) distribution (e.g., MR-EF compared with LVG-EF: r = 0.87, p less than 0.05 for RCA; and r = 0.48, p = NS for LAD). The best expression of relative MI volume appeared to be based upon absolute volume of regionally-thinned LV wall multiplied by a correction factor for its residual contractility and then the addition of a volume correcting for the amount of regional wall thinning by necrosis (i.e., "total-Fxn" MI volume).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗