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Biomedical subjects

A D Waxman

Publications and source records attributed to A D Waxman.

At least 19 recordsLinked to original sources
PubMed1992

Use of thallium 201 in tumor evaluation.

The Council on Scientific Affairs of the California Medical Association presents the following inventory of items of progress in nuclear medicine. Each item, in the judgment of a panel of knowledgeable physicians, has recently become reasonably firmly established, both as to scientific fact and important clinical significance. The items are presented in simple epitome, and an authoritative reference, both to the item itself and to the subject as a whole, is generally given for those who may be unfamiliar with a particular item. The purpose is to assist busy practitioners, students, researchers, or scholars to stay abreast of these items of progress in nuclear medicine that have recently achieved a substantial degree of authoritative acceptance, whether in their own field of special interest or another. The items of progress listed below were selected by the Advisory Panel to the Section on Nuclear Medicine of the California Medical Association, and summaries were prepared under its direction.

Humans↗
PubMed1991

Scintigraphic findings mimicking focal nodular hyperplasia in a case of hepatoblastoma.

Hepatoblastoma is a primary liver neoplasm in which prompt diagnosis and resection are critical to long-term survival. Liver scintigraphy using Tc-99m sulfur colloid and Tc-99m iminodiacetic acid (IDA) derivatives has been used in the evaluation of hepatic masses. Most space-occupying lesions of the liver appear as photopenic regions following either Tc-99m SC or IDA agents. Two exceptions have been reported. Focal nodular hyperplasia (FNH) has been shown to have variable colloid uptake, which is dependent upon the number of Kupffer cells per given volume. Many patients with FNH will demonstrate activity within the FNH to be greater or equal to the normal liver. In addition, two cases of hepatoblastoma have been reported to show colloid activity within the tumor, and in one patient slight uptake of Tc-99m IDA was noted in the tumor 15 minutes postinjection. The current case demonstrates a hepatoblastoma in which the scintigraphic findings with Tc-99m SC and Tc-99m IDA were similar to those reported, with retention of IDA far greater than the previously reported case.

Carcinoma, Hepatocellular↗
PubMed1991

Nuclear oncology.

Nuclear scintigraphy in the evaluation of patients with cancer is a significant part of the practice of clinical nuclear medicine. The oncologic applications in nuclear medicine are dynamic in that traditional techniques are undergoing change due to the development of new pharmaceutical agents and instrumentation. New scintigraphic applications in oncologic diagnosis, staging, and monitoring of therapy are emerging. The impact of these tests on the clinical management of cancer is significant.

Bone Neoplasms↗
PubMed1989

Occult fractures of the proximal femur: MR imaging.

Coronal T1-weighted magnetic resonance (MR) images were obtained on a 1.5-T system in 23 patients in whom there was a high clinical suspicion of hip fracture although initial radiographs were normal. MR imaging correctly demonstrated fracture in nine of nine patients; the precise configuration of the fracture line was delineated in eight patients. MR imaging was useful in excluding fractures in 14 of 14 patients, who were subsequently followed up clinically for a minimum of 3 months. Radionuclide scans were positive in four of four patients with fractures and equivocal in one patient who was subsequently demonstrated to have no fracture. Additional imaging studies were requested by clinicians in all cases in which the bone scan was positive. The results of this study suggest that MR imaging can provide a rapid, cost-effective, and anatomically precise diagnosis of hip fracture in patients with normal or equivocal initial radiographs. The specificity of the diagnosis achieved can obviate supplemental imaging examinations, with their attendant additional expense and radiation exposure.

Aged↗
PubMed1989

Incidental detection of hematopoietic hyperplasia on routine knee MR imaging.

An unusual appearance of the marrow of the distal femur, characterized by confluent foci of diminished signal intensity replacing the normally expected bright signal of fatty marrow on all pulse sequences, was encountered in 10 asymptomatic patients undergoing routine knee MR imaging. This prompted initial concern about the possibility that this appearance was due to lymphoma or occult myeloproliferative malignancy. All patients were mild to moderately obese, and all but one were women. Peripheral blood analysis was obtained in nine patients and was normal in five. The other four were cigarette smokers with a peripheral leukocytosis. Bone-marrow biopsy of the distal femur in two patients and of the iliac crest in three, performed to exclude malignancy, showed hypercellular but otherwise normal-appearing hematopoietic (red) marrow. The patients have been followed for 4-15 months without evidence of malignancy. We conclude that extensive foci of hematopoietic marrow may be encountered incidentally in patients undergoing MR examination. Careful follow-up to date suggests that this most likely represents a benign process and that patients in whom this appearance is encountered can be managed conservatively.

Adult↗
PubMed1988

Comparison of magnetic resonance imaging and radionuclide imaging in the evaluation of renal transplant failure.

Magnetic resonance imaging (MRI) was compared with radionuclide scintigraphy (RNS) in 16 patients with renal transplants undergoing renal failure to determine which modality could best discriminate between rejection, acute tubular necrosis (ATN), and cyclosporin nephrotoxicity (CN). Although all rejecting transplants had reduced corticomedullary differentiation (CMD) on T1-weighted MR images, four of five cases of ATN had appearances that could not be distinguished from rejection. A normal CMD suggests nonrejection, but diminished CMD is nonspecific. Tc-99m DTPA/I-131 hippuran RNS was superior to MRI in differentiating rejection from ATN. Although ATN and CN have similar RNS patterns, this distinction can usually be made based on the clinical time course. Other potential uses of MRI in the evaluation of the renal transplants are discussed.

Acute Kidney Injury↗
PubMed1988

False-positive iodine-131 body scan caused by a large renal cyst.

Focal I-131 accumulation is generally a reliable indicator of functioning thyroid tissue or a differentiated thyroid cancer metastasis. Normal accumulation of activity may be seen in areas such as the intestinal tract, liver, and salivary glands. This report describes a patient with significant accumulation of I-131 in the right upper quadrant of the abdomen. The abnormality, first thought to represent metastatic thyroid carcinoma, was subsequently proven to be accumulation within a large renal cyst.

Abdominal Neoplasms↗
PubMed1988

Gallium-67 citrate localization in osteoclast nuclei of Paget's disease of bone.

Gallium-67 citrate scintigraphy has been used to indicate the extent of bone involvement in patients with Paget's disease of bone and is an excellent marker in monitoring the effects of specific therapy. Since gallium uptake is dependent on cellular function, autoradiographic techniques can be applied to cells of Paget's lesions to understand better the mechanism of [67Ga]citrate uptake. Bone biopsies were obtained from sites of increased uptake using [67Ga]citrate scintigraphy in two patients with Paget's disease. In both patients electron microscopic autoradiographs demonstrated a high concentration of silver grains over the nuclei of osteoclasts. The cellular mechanism is unknown but may be related to the known inhibitory effect of calcitonin on osteoclast activity. The association of [67Ga]citrate with the nucleus of the osteoclasts is unique and different from tumor cells in which there is a high association of [67Ga]citrate with the lysosome fraction within the cytoplasm.

Autoradiography↗
PubMed1987

Failure of episodic high-dose oral verapamil therapy to convert supraventricular tachycardia: a study of plasma verapamil levels and gastric motility.

The practicality of administering large oral doses of verapamil tablets to terminate supraventricular tachycardia (SVT) was investigated in 10 patients. A pilot study in four patients showed that unexpectedly low plasma levels (less than 40 ng/ml) were obtained 60 minutes after administering 160 mg or 240 mg of verapamil during SVT. Nuclear studies in the six other patients showed that fractional liquid gastric emptying times (T) were significantly prolonged in SVT compared to sinus rhythm (SR), p less than 0.05 from T 1/3 onward. Further verapamil absorption studies (200 to 360 mg) performed during SVT and SR in five of six patients showed that peak verapamil levels in four patients in SVT were 23% to 71% lower than in sinus rhythm, where they had peaked at greater than 250 ng/ml 60 minutes post verapamil ingestion, and areas under the plasma concentration time curves were 26% to 100% (mean 67%) less in SVT than in SR for all five patients. SVT was terminated by verapamil in one patient after 40 minutes and the rate of SVT was slowed after 90 minutes in two other patients. Thus plasma verapamil levels are considerably reduced during SVT as compared to SR, and changes in gastric emptying are likely a contributing cause. Since SVT was converted to sinus rhythm in only 1 of 10 patients within 1 hour, large oral doses of verapamil tablets appear unsatisfactory for the episodic treatment of SVT.

Administration, Oral↗
PubMed1987

Nuclear medicine techniques in the evaluation of pulmonary neoplasia.

Many noninvasive imaging techniques are available for evaluating patients with pulmonary neoplastic processes. Computed tomography, magnetic resonance imaging, and gallium scintigraphy, while having made major contributions to the noninvasive workup of patients with pulmonary neoplastic processes, are inadequate for purposes of accurate pathologic staging. A more complete understanding of the potential for existing techniques utilizing gallium 67 and thallium 201 along with the development of new radiopharmaceuticals coupled with recent advances in detection equipment will further expand the role of nuclear medicine in the noninvasive assessment of pulmonary neoplasias.

Carcinoma, Bronchogenic↗
PubMed1986

The role of nuclear medicine in pulmonary neoplastic processes.

It has been demonstrated that the single most important factor in determining survival in patients with bronchogenic carcinoma is the extent of spread of metastasis from the primary lesion. This explains the extensive efforts in developing accurate staging tests for pulmonary tumors, both primary and metastatic, with special emphasis on the determination of pulmonary hilar and mediastinal spread of disease. Continued improvements in nuclear medicine instrumentation along with the development of tumor specific radiopharmaceuticals, as well as agents that have the capability of tracking tumor viability, have changed the orientation of scintigraphic techniques in the evaluation of pulmonary neoplastic processes. Gallium scintigraphy is no longer considered as a primary imaging modality in the staging of pulmonary tumors, and in most institutions has been replaced by computed tomography (CT) for this purpose. It has been demonstrated that gallium, relative to other imaging modalities, is a sensitive indicator of hilar spread of tumor. However, because of the normally high background activity within the sternum and spine, mediastinal abnormalities are poorly detected. Since most pulmonary tumors metastasize via regional nodes to the pulmonary hilum and then to the mediastinum, the high sensitivity for the detection of pulmonary hilar abnormalities and the high specificity for mediastinal lesion detection suggest that gallium scintigraphy is a valuable adjunctive test when used appropriately. Thallium 201 as a tumor agent is being studied by several institutions. Preliminary results indicate a high degree of sensitivity for the detection of pulmonary hilar and mediastinal lesions and there are early indications that thallium is a promising agent to evaluate tumor viability. With the development of new generation monoclonal antibodies, the prospects for highly sensitive and specific agents for detecting hilar and mediastinal spread of tumor is extremely encouraging. CT and NMR have made major contributions to the noninvasive workup of patients with bronchogenic carcinoma. Neither modality has been demonstrated to be accurate enough to adequately evaluate this patient population. Thus, there is a critical need for new noninvasive tests that will accurately assess the status of the patient so that appropriate therapy can be instituted.

Antibodies, Monoclonal↗
PubMed1986

MR imaging of pulmonary emboli: an experimental study in dogs.

Experimental pulmonary emboli, consisting of tantalum-labeled autologous blood clots and barium-labeled 3-mm plastic spheres that did not produce an MR signal, were introduced through the femoral vein into each of five dogs. The sensitivity of MR to detect autologous clots of known size was assessed, and the size of the clot on MR was compared with its actual size. Emboli were localized by using chest radiographs made in multiple projections. Cardiac-synchronized MR imaging was performed on a 0.35-T superconducting magnet and was followed by a 99mTc macroaggregated lung scan. All 12 blood clots larger than 3 mm, and three of 20 clots less than 3 mm in transverse diameter were correctly visualized with MR. Five of the 15 clots seen on MR were larger than 150% of the actual size. There were nine false-positive emboli on MR. Two of six plastic spheres resulted in an abnormal signal on MR. MR signal from pulmonary emboli results from the thrombus itself and probably also from slow blood flow proximal to the obstruction. MR may be of value in detecting pulmonary emboli; clinical trials to evaluate its usefulness should be carried out.

Animals↗
PubMed1986

Regional comparison of technetium-99m DTPA aerosol and radioactive gas ventilation (xenon and krypton) studies in patients with suspected pulmonary embolism.

The regional distribution of [99mTc]DTPA aerosol was compared with that of 133Xe (n = 30) and krypton (n = 24) in a group of patients with suspected pulmonary embolism. All patients had an aerosol study using a recently available commercial generator system, a ventilation study with one of the gases, and perfusion imaging. Regional information was assessed visually on xenon, krypton, and aerosol studies independently by considering each lung as three equal-sized zones. In addition, gas ventilation findings peripheral to regions of aerosol turbulence ("hot spots") were evaluated. Only 64% of the zones were in complete agreement on xenon and aerosol. Most of the discordance between xenon and aerosol was accounted for by minor degrees of 133Xe washout retention in zones that appeared normal in the aerosol study. An agreement rate of 85% was noted between 81mKr and aerosol regionally. The regions of discordance between aerosol and gas studies, however, usually were associated with unimpressive perfusion defects that did not change the scintigraphic probability for pulmonary embolism in any patient. Regarding zones of aerosol hyperdeposition, 76% had associated washout abnormalities on xenon; however, there was no correlation between the presence of these abnormalities or perfusion abnormalities. The results confirm the high sensitivity of 133Xe washout imaging, but suggest that radioaerosol imaging will detect most parenchymal abnormalities associated with perfusion defects of significance.

Adult↗
PubMed1985

Correlation of thyroglobulin measurements and radioiodine scans in the follow-up of patients with differentiated thyroid cancer.

Correlation of radioiodine (131I) scans and serum thyroglobulin (Tg) concentrations were performed in the follow-up of 85 differentiated thyroid cancer patients who had undergone total thyroidectomy. Tg results were also compared with the control group of 33 thyroidectomized patients with no evidence of thyroid carcinoma and normal values for Tg established. Excellent correlation between Tg and scans was noted in patients with scan evidence of metastasis distant from the neck. Poor correlation was present in patients with scan evidence of local neck metastasis only, thyroid bed activity, and those with mediastinal activity. In addition, in 8% of the patients, the Tg assay could not be performed because of interfering antibodies. The conclusion is that elevated Tg concentration is a good indicator of metastasis outside of the neck as detected by 131I scans. Caution should be used when Tg alone is used in evaluating local neck metastasis demonstrated on scans. The significance of mediastinal activity warrants further investigation.

Adolescent↗
PubMed1985

Treatment rationale in thyroid carcinoma. Effect of scan dose.

The authors have previously shown that the definition of ablation of thyroid tissue in patients treated with thyroidectomy and radioiodine (I-131) for thyroid carcinoma depends upon the dose of I-131 used to scan the patient. The therapeutic response to I-131 therapy was evaluated in a group of ten differentiated thyroid cancer patients who had a negative 2-mCi (-2 mCi) diagnostic study, but had a positive 10-mCi (+10 mCi) diagnostic study (group 1) during their follow-up evaluation. These results were compared to another group of ten differentiated thyroid cancer patients who received I-131 ablation therapy based on a positive 2-mCi (+2 mCi) I-131 scan (group 2). Six patients in group 1 and eight in group 2 had improvement or ablation of residual tissue based on the 10-mCi scan following therapy. The difference in response between the two groups was not statistically significant (P = 0.63) by two-tailed Fisher's exact test, indicating that even patients with -2-mCi, but +10-mCi scans may respond to I-131 therapy. Whether the large dose therapy makes any impact on the clinical outcome has not been answered by this study.

Adolescent↗
PubMed1985

Evaluation of low-dose radioiodine ablation therapy in postsurgical thyroid cancer patients.

Nineteen patients with differentiated thyroid carcinoma were given low dose (30 mCi) radioiodine therapy for the ablation of residual thyroid tissue following total thyroidectomy. Using 5- to 10-mCi diagnostic I-131 scans, ablation was achieved in two of 19 patients following the first low dose and three of 12 patients following the second low-dose therapy. The ablation response was 53% (ten of 19) following one large dose (100 mCi) in another concurrent group of 19 patients. The ablation response following the first low dose when compared with the first high-dose therapy was significantly lower (P = 0.015). The combined ablation response following first and second low doses (five of 14) when compared to a single large dose was not significantly different (P = 0.534). The use of low-dose-I-131 therapy, although not as effective as large dose therapy, may be warranted in patients resistant to entering the hospital for therapy. However, ablation as defined by a five- to ten-mCi I-131 scan can be expected to occur in only one third of the patients after two attempts at ablation, while a single 100-mCi regimen can be successful in achieving ablation in over one half of the patients after the first attempt.

Adenocarcinoma↗
PubMed1985

Postperfusion xenon-133 ventilation scintigraphy with a narrow window.

Xenon-133 postperfusion lung scintigraphy using 10% windows was compared with standard posterior preperfusion 133Xe ventilation scanning in 33 patients. The postperfusion 133Xe study identified all major defects and washout abnormalities. In five patients, the assessment of match or mismatch of defects was improved because of optimal positioning of the postperfusion ventilation study. Computer subtraction of background technetium-99m macroaggregated albumin activity improved detection of mild washout abnormalities in eight patients but did not change the diagnostic category in any case. Postperfusion ventilation scanning using 10% windows (with or without background computer subtraction) is an alternative to preperfusion ventilation scanning for major V/Q abnormalities.

Adult↗