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Biomedical subjects

R Henkin

Publications and source records attributed to R Henkin.

29 records · Page 2Linked to original sources
PubMed1987

Effects of analyzed signal duration and phase on the results of fast fourier transform analysis of the surface electrocardiogram in subjects with and without late potentials.

A microcomputer-based system capable of performing time- and frequency-domain analysis on the same set of acquired and signal-averaged raw data was used to correlate late potentials detected in the time domain with the results of frequency-domain analysis. Ten patients with spontaneous or inducible sustained ventricular tachycardia (VT) known to have abnormal late potentials in the time-domain signal-averaged electrocardiogram and 10 normal subjects without late potentials were studied. Fast Fourier transform analysis was performed on a segment that comprised the last 40 ms of the QRS and the ST segment up to the onset of the T wave as identified visually. The high-frequency signal content, expressed as the area ratio or the peak magnitude, was found to be markedly dependent on the length of the analyzed QRS-ST segment. A change of as little as 3 ms in the duration of the estimated QRS-ST segment changed the results of the frequency analysis across proposed boundaries of normalcy in normal subjects and in patients with VT. This resulted in both false-negative and false-positive conclusions. Similar results were obtained when the effects of varying analyzed signal length or phase were studied using a pure synthesized sine wave signal. For frequency analysis to be clinically useful and reproducible, standards of normalcy must be established for a signal region of fixed duration or the technique must be modified so as to be insensitive to duration of signal sample.

Adult↗
PubMed1987

Routine use of the thallium-technetium scan prior to parathyroidectomy.

The merit of the preoperative localization of parathyroid tumors with thallium-technetium subtraction imaging is a subject of current debate in the treatment of primary hyperparathyroidism. Eighty patients with hyperparathyroidism underwent preoperative subtraction scintigraphy with 201Tl Cl and 99mTcO4; scan results were correlated with the operative identification and histopathology of the resected parathyroid tissue. The true-positive, false-positive and false-negative rates of these scans were compared between patients with tumors in normal and ectopic anatomic locations and between patients undergoing an initial and reoperative neck exploration. The scan was clearly valuable in patients with one or more prior neck explorations. True-positive scans were obtained in seven (77%) of nine such patients. The scan was also valuable in patients who had ectopic tumors (six mediastinal, seven intrathyroid, and two in the carotid sheath). Twelve (80%) of these 15 ectopic tumors were correctly localized either prior to their first operation or before subsequent explorations. In contrast, only 33 (50%) of 65 patients had a true-positive scan prior to their first operation and when the tumor was not in an ectopic location. In summary, in this series, the thallium-technetium scan was correct in only 50 per cent of patients undergoing an initial operation. However, it was positive in 77 per cent of patients who had at least one prior neck exploration and in 80 per cent of patients with an ectopic parathyroid tumor. These results support the selective use of this valuable imaging and localization tool.

Adenoma↗
PubMed1986

Radiologic diagnosis of an intra-abdominal abscess. Do multiple tests help?

A review was made of the charts of 94 patients who underwent ultrasonography (US), computed tomography (CT), and gallium citrate Ga 67 (Gall) scan to rule out intra-abdominal abscesses. Of all the clinical and laboratory data, only the presence of pain and tenderness differentiated patients with and without abscesses. A review of radiologic data showed that CT was superior to US, and that US was superior to Gall scan with regard to sensitivity, specificity, accuracy, and positive and negative predictive values. When multiple radiologic tests were performed, results agreed in 72% of cases; therefore, the additional tests were essentially redundant. When radiologic test results disagreed, accuracy rates were CT, 0.86; US, 0.00; and Gall scan, 0.44. These findings suggest that, except to rule out pelvic abscesses in the presence of pelvic inflammatory disease, CT is usually the only special radiologic test that should be performed to localize a suspected intra-abdominal abscess.

Abdomen↗
PubMed1986

Parathyroid autotransplantation in forty-four patients with primary hyperparathyroidism: the role of thallium scanning.

Forty-four patients with primary hyperparathyroidism were followed for 18 to 126 months after subtotal or total parathyroidectomy and parathyroid autotransplantation. Indications for autotransplantation included the devascularization of parathyroid glands during concomitant thyroid lobectomy or total thyroidectomy and the excision of the only remaining parathyroid tissue in patients with persistent hyperparathyroidism after previous unsuccessful parathyroidectomies. Before implantation, all parathyroid tissue was histologically evaluated by frozen-section light microscopy with hematoxylin and eosin stain. Fifteen patients had histologically normal implants; to date none of these patients have developed recurrent hyperparathyroidism. Twenty-nine patients had either adenomatous or hyperplastic parathyroid tissue used for implants; two of these patients developed graft-dependent recurrent hyperparathyroidism 4 and 7 years later. In both patients the grafts were preoperatively localized by thallium scanning and their resection restored eucalcemia. One hundred thirty-one patients from 11 series in the current literature had a cumulative incidence of 17.5% for presumed graft-dependent recurrence and a 9.2% incidence of graft excision followed by eucalcemia. In comparison, in the present series the incidence of graft-dependent recurrent hyperparathyroidism in patients with either adenomatous or hyperplastic implants stands at 6.9%. In contrast, in 15 patients with normal parathyroid tissue implants, the incidence was zero.

Adenoma↗
PubMed1985

The role of sincalide cholescintigraphy in the evaluation of patients with acalculus gallbladder disease.

Thirty-six patients with biliary colic and normal oral cholecystograms, upper gastrointestinal tract roentgenograms, and results of gallbladder ultrasonography underwent sincalide-stimulated biliary excretion scanning. Nineteen of these patients subsequently underwent cholecystectomies. Gallbladder ejection fractions (EFs) ranged from 0% to 88% (mean, 38%) and nine of 19 patients had exact pain reproduction with sincalide. All patients except one (EF, 35%) were cured of their symptoms. However, five patients were also cured who had a normal EF (greater than 50%). Histologically, 11 gallbladders showed chronic cholecystitis and eight were normal. We conclude that the sincalide biliary excretion scan is a useful test to study this group of patients. In patients with a decreased EF, cholecystectomy can be recommended with a high probability of symptom relief. In patients with normal EFs, clinical judgment is required, as some of these patients (five of five in this series) may still benefit from operation.

Adult↗
PubMed1985

Localization of ectopic parathyroid adenomas by the technetium-thallium subtraction scan.

Among numerous methods utilized for preoperative localization of hyperfunctioning ectopic parathyroid tissue, the technetium-thallium scan appears to be a major advance. Eight patients are presented where this method located ectopic parathyroid tissue in the neck, in the mediastinum, within the pericardium, and within the thyroid gland. To date, these findings have been confirmed operatively in five of the eight patients. On the basis of our limited experience, the authors believe that this is a valuable method in the preoperative localization of ectopic parathyroid tissue, especially in patients with persistent or recurrent hyperparathyroidism following a thorough neck exploration.

Adenoma↗
PubMed1981

Clinical parameters related to anorexia.

Caloric intake was studied in 89 cancer patients who recorded diet diaries. Twenty-five percent had caloric intake below their calculated basal energy expenditure (BEE). An additional 45% had caloric intakes between 1.0 and 1.5 x BEE. Patients reported symptoms referable to the oronasal area and the gastrointestinal tract as possible factors in decreased eating. Food intake is controlled by several categories of cues and one or more of these may be altered in cancer patients to decrease caloric intake.

Anorexia↗