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Biomedical subjects

M G Velchik

Publications and source records attributed to M G Velchik.

At least 55 records · Page 3Linked to original sources
PubMed1985

The "liver scan" appearance in cholescintigraphy. A sign of complete common bile duct obstruction.

One hundred consecutive Tc-99m IDA hepatobiliary scans were reviewed revealing 14 scans (14%), that showed nonvisualization of the common bile duct (CBD), gallbladder (GB), and small bowel (SB), but good hepatic uptake of Tc-99m IDA derivative, a pattern designated by us as "the liver scan appearance." In 11 of 14 cases (79%), the diagnosis of complete CBD obstruction was confirmed by surgery, percutaneous transhepatic cholangiogram (PTC), endoscopic retrograde cholangiopancreatography (ERCP), and/or percutaneous needle biopsy (PBx). Common bile duct obstruction was suspected but not proven in the other three cases. The cholescintigraphic, ultrasound, PTC, ERCP, intraoperative cholangiogram, clinical, laboratory, and surgical findings are presented and correlated. The "liver scan-appearance" by cholescintigraphy should suggest a diagnosis of complete common bile duct obstruction; however, it does not specifically differentiate between stone or tumor as the cause of obstruction.

Cholangiography↗
PubMed1985

Sources of variability in quantitative thallium analysis.

Nineteen patients undergoing exercise thallium scanning had two separate redistribution 40 degree LAO acquisitions obtained; the gamma camera was repositioned between the views. Data were analyzed by generating 60-point circumferential profile curves for each of the 38 images and the variability of individual points and 18 degrees and 36 degrees segments was determined. Intraobserver variability, assessed by reanalyzing the scans one week later, was approximately 5.0%. The interobserver variability was of similar magnitude (approximately 6%). The total reimaging variability was, however, significantly larger (approximately 13%). It is concluded that quantitative image analysis is highly reproducible with low intra- and interobserver variabilities, but the act of repositioning and reimaging introduces significant additional variability. This may limit the ability of quantitative thallium scanning to document changes in the size of defects.

Adult↗
PubMed1985

Radionuclide imaging of the urinary tract.

This article describes the role of nuclear medicine in the evaluation of the genitourinary tract. The technical aspects of radionuclide imaging (radiopharmaceuticals, radiation dosimetry, instrumentation, and method) are briefly presented, and each of the indications for renal scintigraphy--including the evaluation of differential renal function, hypertension, obstruction, renal transplants, masses, trauma, congenital anomalies, vesicoureteral reflux, and infection--are discussed. The relative advantages and disadvantages of radionuclide imaging with respect to alternative radiographic examinations (such as intravenous urography, ultrasonography, CT, angiography, and magnetic resonance imaging) are emphasized wherever applicable.

Graft Rejection↗
PubMed1985

Pulmonary scintigraphy in a patient with multiple pulmonary arteriovenous malformations and pulmonary embolism.

The scintigraphic findings in a patient with multiple pulmonary arteriovenous malformations (AVMs) complicated by superimposed pulmonary embolism are reported. Although pulmonary AVMs may cause small subsegmental scintigraphic abnormalities, the demonstration of perfusion defects which are segmental or larger should strongly suggest the presence of superimposed pulmonary embolism in a patient with multiple pulmonary AVMs.

Adult↗
PubMed1985

Osteomalacia. An imposter of osseous metastasis.

A case of osteomalacia with multiple asymmetrically distributed pseudofractures (Looser's zones) simulating metastases is presented. Radiographic correlation is essential to increase specificity and avoid misinterpretation.

Aged↗
PubMed1984

Validation of Fourier amplitude ratio to quantitate valvular regurgitation.

It has previously been shown that patients with valvular regurgitation can be identified by the ratio of left and right ventricular amplitude values obtained from first harmonic Fourier analysis of the gated blood pool scan. The present study was designed to validate the accuracy of this technique for quantifying the amount of valvular regurgitation. In a blinded analysis of 19 patients who underwent cardiac catheterization, there was a close correlation between the radionuclide and hemodynamic determination of the amount of regurgitation (r = 0.84). The interobserver agreement for calculating the radionuclide data was also high (r = 0.88). These results suggest that the Fourier ventricular amplitude ratio is an accurate and reproducible technique for quantifying valvular regurgitation by gated blood pool scanning.

Adult↗
PubMed1984

Variation of the spleen-liver activity ratio due to a change in position.

The ratio of splenic to hepatic activity in the posterior view of a Tc-99m SC liver-spleen scan has been used as an indicator of parenchymal disease. Analysis of liver-spleen scans from a series of patients acquired in both the supine and erect positions revealed that the spleen-liver ratio varied considerably with a change in the patient position. Qualitatively there was a shift of colloid from the liver to the spleen in five of 18 supine views and ten of 18 erect views. Quantitative analysis of 37 cases showed that the median erect spleen-liver ratio was 20% greater than the spleen-liver ratio observed in supine patients. Criteria for an abnormal spleen-liver ratio need to be established in each position.

Colloids↗
PubMed1984

Gallbladder carcinoma. Another cause of the distended photon-deficient gallbladder in cholescintigraphy.

A case report of an 82-year-old woman with carcinoma of the gallbladder is presented. Technetium-99m DISIDA cholescintigraphy demonstrated nonvisualization of the gallbladder, with a large photon-deficient region corresponding to the gallbladder fossa, with medial displacement of the common bile duct. Carcinoma of the gallbladder has not been previously described as a cause of this scintigraphic pattern.

Adenocarcinoma↗
PubMed1983

Unusual appearance of a highly vascular lesion on Tc-99m DISIDA hepatobiliary scintigraphy.

A lesion was identified on the late images of a hepatobiliary scintigraphic study, but was not detected on the very early images, due to its enlarged blood pool. This combination of scan findings has not been previously described. The implication of the observation is that one must examine all the images of the hepatobiliary study in an effort to detect space-occupying lesions of the liver.

Aged↗
PubMed1983

Fourier amplitude ratio: a new way to assess valvular regurgitation.

The stroke-volume ratio determined from the equilibrium gated blood-pool study has been utilized to assess valvular regurgitation, but it is difficult to get reproducible results using generally available equipment. We have developed a new approach utilizing the Fourier amplitude ratio of the left and right ventricles, which is easily implemented and reproducible. Initial clinical experience shows that 17 patients with valvular regurgitation were clearly distinguished from 30 patients without valve disease.

Aortic Valve Insufficiency↗