PubMed Health⌕ Search

Biomedical subjects

L P Adler

Publications and source records attributed to L P Adler.

At least 19 recordsLinked to original sources
PubMed1999

Positron emission tomography for evaluating para-aortic nodal metastasis in locally advanced cervical cancer before surgical staging: a surgicopathologic study.

PURPOSE: Positron emission tomographic (PET) scanning provides a novel means of imaging malignancies. This prospective study was undertaken to evaluate PET scanning in detecting para-aortic nodal metastasis in patients with locally advanced cervical carcinoma and no evidence of extrapelvic disease before planned surgical staging lymphadenectomy. MATERIALS AND METHODS: After 20 mCi of 2-[18F]fluoro-2-deoxy-D-glucose (FDG) were administered intravenously, the abdomen and pelvis were scanned. Continuous bladder irrigation was used to reduce artifact. Patients were classified by the presence or absence of FDG uptake in the primary tumor and in pelvic or para-aortic nodes. Para-aortic node metastases were classified as present or absent according to a standardized staging procedure. Pelvic node metastases were similarly classified in a subset of patients who underwent pelvic node resection. RESULTS: Thirty-two patients with stage IIB (n = 6), IIIB (n = 24), and IVA (n = 2) tumors were studied. Fluorodeoxyglucose was taken up by 91% of the cervical tumors. Six of eight patients with positive para-aortic node metastasis had PET scan evidence of para-aortic nodal metastasis. One of the two false-negatives had only one microscopic focus of metastatic cancer. In the para-aortic nodes, PET scanning had a sensitivity of 75%, a specificity of 92%, a positive predictive value of 75%, and a negative predictive value of 92%. Fluorodeoxyglucose para-aortic nodal uptake conferred a relative risk of 9.0 (95% confidence interval, 2.3 to 36.0) for para-aortic nodal metastasis. All 10 of 17 patients with metastasis were predicted by PET scanning (P < .001); five of these patients had abnormalities on computed tomographic scans. CONCLUSION: Cervical cancers have a high avidity for FDG. The use of PET-FDG scanning accurately predicts both the presence and absence of pelvic and para-aortic nodal metastatic disease.

Aorta↗
PubMed1999

Simultaneous recovery of size and radioactivity concentration of small spheroids with PET data.

UNLABELLED: Quantification of tumor activity is used to predict prognosis and discriminate benign from malignant lesions identified by PET. Accurate quantitation of small lesions requires correction for the partial volume effects. Such a correction is often based on the recovery coefficient (RC), which depends on the lesion size, the object-to-background ratio (OBR) and physical properties of the media. The purpose of this investigation was to determine whether a model-based optimization method to simultaneously recover the size and the activity concentration of small spheroids could improve estimates of lesion radioactivity when object size is unknown. For reference, we compared our method with a widely used approach, RC correction, that requires the object size to be known. METHODS: A three-dimensional, spatially varying, object size- and contrast-dependent Gaussian model of the point spread function (PSF) of an ECAT EXACT was developed. The observed dependence of the PSF on random coincidences and measured-peak/background activity were included in the PSF using three adjusting factors. Size and radioactivity concentration of a spheroid were estimated by adjusting size and concentration until model output best matched the image data. Elliptic and circular phantoms both containing seven hot spheroids, with OBRs ranging from 5.6 to 0 background, were evaluated. RESULTS: The proposed quantification method reduced the activity error by 11%-63% of the error obtained without correction. The greatest error reduction occurred for small spheroids. The average error in radius estimation ranged from 2% to 48%, wherein the smallest spheroid produced the largest errors. For spheroids with diameters from 8 to 22 mm, Student t test (paired, one-tail) showed the proposed method significantly improved accuracy (P < 0.05) in comparison with the RC method and also in comparison with optimization without the three adjusting factors. CONCLUSION: The model-based optimization method improved estimation of radioactivity concentration over that corrected by the RC method and that made without any correction. It also provided accurate estimation of size for spheroids larger than 6 mm in diameter.

Models, Theoretical↗
PubMed1998

Elimination of artifactual accumulation of FDG in PET imaging of colorectal cancer.

BACKGROUND: Positron emission tomography (PET) with fluorine-18 labeled deoxyglucose (FDG) can detect tumor recurrences in surgical patients that are otherwise difficult to assess by CT, as well as distant metastases and small malignant nodes that are not identified by other imaging modalities. However, the evaluation of such malignancy is complicated by urinary and colonic concentrations of FDG. Methods and examples of the elimination of artifactual accumulation of FDG in PET imaging of the abdomen and pelvis are presented. METHODS: Elimination of artifactual accumulation requires patient preparation that begins with cleansing of the colon using an isosmotic solution taken the evening prior to examination. Approximately 500 MBq of F-18 FDG is intravenously administered upon arrival at the PET facility and then the patient is hydrated. After administration of furosemide, a Foley catheter with a drainage bag is placed and the patient is then scanned. Just prior to scanning over the pelvis, normal saline is delivered retrogradely into the urinary bladder. At the end of scanning, the patient voids and repeated pelvic images are obtained. RESULTS: These routines yield a clean scanning field. Lesions that will generally be missed because they are obscured by FDG accumulations along the colon or in the kidneys, ureters, or bladder are better visualized and identified with greater confidence. Artifacts that lead to misinterpretation also are reduced. CONCLUSION: Elimination of artifactual accumulation of FDG in the colon and urinary system is essential if primary cancer, associated adenopathy, or subtle recurrences are to be evaluated in FDG PET imaging of the abdomen and pelvis.

Abdomen↗
PubMed1998

A nonlinear spatially variant object-dependent system model for prediction of partial volume effects and scatter in PET.

Accurate quantitation of small lesions with positron emission tomography (PET) requires correction for the partial volume effect. Traditional methods that use Gaussian models of the PET system were found to be insufficient. A new approach that models the non-Gaussian object-dependent scatter was developed. The model consists of eight simple functions with a total of 24 parameters. Images of line and disk sources in circular and elliptical cylinders, and an anthropomorphic chest phantom were used to determine the parameter values. Empirical rules to determine these parameter values for various objects based on those for a reference object, a 21.5-cm circular cylinder, were also proposed. For seven spheroids and a 3.4-cm cylinder, pixel values predicted by the model were compared with the measured values. The model-to-measurement-ratio was 1.03+/-0.07 near the center of the spheroids and 0.99+/-0.03 near the center of the 3.4-cm cylinder. In comparison, the standard single Gaussian model had corresponding ratios of 1.27+/-0.09 and 1.24+/-0.03, respectively, and the corresponding ratios for a double Gaussian model were 1.13+/-0.09 and 1.05+/-0.01. Scatter fraction (28.5%) for a line source in the 21.5-cm cylinder was correctly estimated by our model. Because of scatter, we found that errors in the measurement of activity in spheroids with diameters from 0.6 to 3.4 cm were more significant than previously appreciated.

Algorithms↗
PubMed1998

Innovations in breast cancer imaging: PET for diagnosis and follow-up.

Could positron emission tomography (PET), which identifies the higher metabolism of malignant tumors, become the noninvasive test needed to assess the thousands of falsely positive mammograms? Could serial scans be used to evaluate response to chemotherapy? This team examines the data on current and potential uses of PET.

Axilla↗
PubMed1997

Axillary lymph node metastases: screening with [F-18]2-deoxy-2-fluoro-D-glucose (FDG) PET.

PURPOSE: To evaluate [fluorine-18]2-deoxy-2-fluoro-D-glucose (FDG) positron emission tomography (PET) of the axilla as a screening test for detecting regional spread of breast cancer. MATERIALS AND METHODS: High-dose FDG PET of the axilla was successfully performed in 50 patients (age range, 36-79 years) with breast cancer before 52 axillary lymph node dissections. Two additional patients had scans that were uninterpretable because of intense myocardial activity that obscured the axilla. RESULTS: The sensitivity and negative predictive value were both 95%, the specificity was 66%, and the overall accuracy was 77%. The only false-negative PET scan was obtained in the largest patient, who had a low-quality scan. CONCLUSION: Patients with negative PET scans had such a low risk for axillary lymph node metastases that axillary dissection was not warranted. Patients with positive PET scans required dissection to confirm the presence and determine the number of positive lymph nodes. Had this algorithm been used to select patients for dissection, approximately $120,000 in charges ($2,300 per patient) would have been saved and 22 patients would have been spared the morbidity of axillary lymph node dissection. Within this study population, PET scans of the axilla were interpreted with sufficient sensitivity for PET to serve as a cost-effective screening test for axillary lymph node metastases.

Adult↗
PubMed1997

Cholescintigraphy in the diagnosis of bile leak after laparoscopic cholecystectomy.

Bile leaks are a recognized complication of laparoscopic cholecystectomy (LC). Different diagnostic approaches have been employed when this condition is suspected. We present our experience with cholescintigraphy as a primary imaging technique for the detection of bile leaks. The medical records of all patients who had cholescintigraphy after LC during a 58-month period were reviewed. Patients were selected for cholescintigraphy if fever unusual abdominal pain, nausea, vomiting, or jaundice were present beyond 36 hours after LC. Bile leaks were suspected in 25 out of 744 patients (3.36%). The nuclear imaging study was true positive in 7 cases and true negative in 18 cases, for a 100 per cent sensitivity, specificity, and accuracy in the detection of bile leaks. Five patients were treated by endoscopic retrograde cholangiopancreatography with stent and/or sphincterotomy, and two patients underwent exploratory laparotomy. None of the patients who underwent endoscopic retrograde cholangiopancreatography required peritoneal drainage. We conclude that cholescintigraphy is sensitive and accurate in the diagnosis of bile leaks. Its use along with a high index of suspicion of a bile leak may prevent the development of bile peritonitis.

Adult↗
PubMed1997

Technical improvements in fluorine-18-FDG PET imaging of the abdomen and pelvis.

UNLABELLED: PET tumor imaging of the abdomen and pelvis is prone to artifacts due to urinary tract activity. A new technique has been developed to reduce such artifacts and enhance study interpretation. METHODS: Thirty minutes after the injection of 18F-FDG, 500 cc 0.45% NaCl were administered intravenously over 30 min and a Foley catheter was placed in the bladder. At the start of imaging (60 min post-injection), furosemide was given (0.3 mg/kg). Prior to imaging the pelvis, the urinary catheter was clamped and saline was introduced retrograde into the bladder until full. RESULTS: This technique has been used successfully in more than 130 patients, resulting in a marked improvement in study quality and tumor detection. CONCLUSION: Hydration and administration of furosemide, along with placement of a Foley catheter in the bladder, have proven effective in eliminating image artifacts originating from the kidneys, ureters and bladder. Backfilling the bladder also provides a well-defined anatomic landmark for study interpretation.

Abdominal Neoplasms↗
PubMed1994

Positron emission tomography and breast masses: comparison with clinical, mammographic, and pathological findings.

BACKGROUND: Positron emission tomography (PET) is a means of imaging tissue based upon its metabolic activity. Initial studies in the field of oncology suggest that PET may be useful for diagnosis, staging, and treatment of various tumors. METHODS: Twenty-eight patients with 37 breast lesions were studied with PET using [fluorine-18] 2-deoxy-2-fluoro-D-glucose (FDG) to assess which clinicopathological characteristics relate to FDG accumulation by the primary tumor. RESULTS: PET-FDG was found to successfully discriminate malignant from benign breast lesions (p = 0.02) and identify axillary lymph node metastases. FDG uptake by the primary tumor was found to be independent of age, menopausal status, race, tumor size, laterality, histologic differentiation, ploidy, DNA index, estrogen or progesterone receptor value, pathologic stage, and serum glucose. Higher tumor nuclear grade and S-phase were associated with more FDG accumulation by the primary tumor compared with normal breast tissue. PET-FDG correctly identified five malignant lesions that were indeterminant for cancer both on clinical breast examination and mammography and identified one occult cancer that was neither palpable nor apparent mammographically. PET-FDG correctly identified clinical occult axillary metastatic cancer in five patients. CONCLUSIONS: This study shows that PET-FDG imaging can distinguish malignant from benign breast lesions among a diverse group of patients and suggests that PET-FDG may not only allow for preoperative staging of patients but also provide information about prognosis. This study provides impetus for continued research into PET-FDG imaging of breast lesions, which could have a major impact on the treatment of breast cancer.

Adult↗
PubMed1994

Right ventricular outflow tract ventricular tachycardia: detection of previously unrecognized anatomic abnormalities using cine magnetic resonance imaging.

OBJECTIVES: This study attempted to determine whether cine magnetic resonance imaging (MRI), because of its unique ability to image the right ventricle, detects abnormalities in patients with right ventricular outflow tract ventricular tachycardia. BACKGROUND: Right ventricular outflow tract ventricular tachycardia occurs in the absence of apparent structural heart disease. METHODS: We compared cine MRI scans in 22 patients with right ventricular outflow tract ventricular tachycardia, 16 subjects without structural heart disease and 44 patients with other cardiovascular diseases. Echocardiography was performed in 21 patients with ventricular tachycardia. RESULTS: All 22 patients with ventricular tachycardia had normal left ventricular function and no evidence of coronary artery disease. Cine MRI revealed right ventricular structural and wall motion abnormalities more often in patients with ventricular tachycardia (21 [95%] of 22) than in normal subjects (2 [12.5%] of 16, p < 0.0001) or patients without arrhythmia (17 [39%] of 44, p < 0.0001). The abnormalities in patients with ventricular tachycardia (fixed focal wall thinning, excavation, decreased systolic thickening) were located in the right ventricular outflow tract, whereas those in patients without arrhythmia were confined to the free wall. Cine MRI demonstrated abnormalities in patients with ventricular tachycardia more often than did echocardiography (21 [95%] of 22 vs. 2 [9%] of 21, respectively, p < 0.0001). CONCLUSIONS: Right ventricular outflow tract ventricular tachycardia was associated with focal structural and wall motion abnormalities of the right ventricular outflow tract that were detected more often by cine MRI than by other imaging modalities and were not present in patients without arrhythmia or in normal subjects.

Adult↗
PubMed1994

Review of some common artifacts in nuclear medicine.

In nuclear medicine, artifacts may simulate a pathologic process; their recognition is therefore necessary to avoid misdiagnosis. Artifacts may be divided into three groups: 1) camera dependent artifacts; 2) radiopharmaceutical dependent artifacts; and 3) patient-related artifacts. The authors present a variety of artifacts and discusses their possible prevention.

Artifacts↗
PubMed1993

Positron emission tomography of thyroid masses.

Nine patients with suspicious thyroid nodules were studied with positron emission tomography (PET) following the administration of [18F]-2-deoxy-2-fluoro-D-glucose (FDG) prior to surgical excision. Three patients were ultimately determined to have papillary carcinoma, four were shown to have follicular adenomas, and two were proven to have multinodular goiters with dominant nodules. All three malignancies and four of the six benign lesions were easily detected visually as areas of increased FDG uptake. While visual analysis alone did not discriminate between the benign and malignant lesions, all three malignancies had dose uptake ratios (DURs) for FDG in excess of 8.5 while the DURs for benign lesions ranged between 1.9 and 6.3. The mean FDG DUR for the three papillary carcinomas (10.9 +/- 3.9; mean +/- SD) was significantly greater (p = 0.0019) than that of the six benign lesions (3.2 +/- 1.7). There was no significant difference between the FDG DUR for the follicular adenomas and the dominant nodules of multinodular goiters. Further research is needed to confirm the usefulness of PET in the differential diagnosis of thyroid nodules, and, in particular, whether or not PET can discriminate between benign and malignant follicular neoplasms.

Adenoma↗
PubMed1993

Scintigraphic detection of bile leaks after laparoscopic cholecystectomy.

Laparoscopic cholecystectomy is widely accepted as an alternative to traditional open cholecystectomy. Its advantages are a shorter hospital stay, earlier return to normal activity, less pain, and improved cosmetic results. However, in the initial experience with this technique, biliary leaks were several times more frequent than in traditional cholecystectomy. Four cases of scintigraphic detection of biliary leaks after laparoscopic cholecystectomy are described. The results of the examination are compared in two cases with endoscopic retrograde cholangiography and in the remaining two with intraoperative findings. Hepatobiliary scintigraphy is suggested for early evaluation of postoperative complications involving the biliary system.

Adult↗