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.

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.

Measurement of human cerebral blood flow with [15O]butanol and positron emission tomography.

Although H2(15)O is widely used for CBF measurement by positron tomography, it underestimates CBF, especially at elevated flow rates. Several tracers, including butanol, overcome this problem, but the short half-life of 15O provides advantages that cause water to remain the tracer of choice. We report the first use and evaluation of 15O-labeled butanol for CBF measurement. Flow measurements made in a similar fashion with water and butanol at 10-min intervals were compared in normal volunteers under resting and hypercapnic conditions. Regional analysis showed good agreement between the tracers at low flows, and significant underestimation of flow by water relative to butanol in regions of elevated flow. The observed relationship between the tracers and the curve-fitted permeability-surface area product for water (133 ml.100 g-1.min-1) follow the known relationship between water and true flow. These observations indicate that [15O]-butanol provided accurate measurements of human regional CBF under conditions of elevated perfusion. We conclude that butanol is a convenient and accurate method for routine CBF determination by positron emission tomography.

Comparison of the effect of temafloxacin, ciprofloxacin, or placebo on cerebral blood flow, glucose, and oxygen metabolism in healthy subjects by means of positron emission tomography.

STUDY OBJECTIVE: To determine the cause of the central nervous system effect of the fluorinated quinolones temafloxacin and ciprofloxacin by measuring cerebral blood flow and metabolism by use of positron emission tomography. DESIGN: This was a prospective, randomized, double-blind, placebo-controlled study. PATIENTS: The patients were 13 healthy, nonsmoking volunteers whose ages ranged from 18 to 40 years. RESULTS: We measured brain blood flow and metabolism by use of positron emission tomography before and after a five-dose course of 750 mg ciprofloxacin, 600 mg temafloxacin, or placebo given every 12 hours. Quinolone administration produced no significant effect on visual (qualitative) reading of the positron emission tomography scans. CONCLUSIONS: We conclude that short-term administration of temafloxacin, ciprofloxacin, or placebo does not significantly alter cerebral glucose or oxygen metabolism. Subjects treated with ciprofloxacin demonstrated a significant decrease in brain blood flow compared with baseline and with temafloxacin- or placebo-treated subjects.

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.

Noninvasive grading of musculoskeletal tumors using PET.

Twenty-five patients with mass lesions involving the musculoskeletal system were studied with positron emission tomography (PET) in order to determine if a relationship exists between histologic grade and tumor uptake of [fluorine-18]2-deoxy-2-fluoro-D-glucose (FDG). There were 6 benign lesions and 19 malignant lesions of various grades. A high correlation (Rho = 0.83) was found between the normalized uptake of tracer and the NCl grade. The high-grade malignancies had significantly greater (p = 0.0091) uptake of FDG than the combination of benign lesions and low-grade malignancies. All lesions with a normalized uptake value of 1.6 or greater were high-grade, while all lesions less than 1.6 represented either benign tumors or low grade malignancies. This strong relationship between FDG uptake and grade among neoplasms from a wide variety of cell types within a single organ system suggests that the technique may be useful in predicting grade even when the cell type is unknown.

Paramagnetic pyrophosphate. Preliminary studies on magnetic resonance contrast enhancement of acute myocardial infarction.

Ferric pyrophosphate (Fe-PyP) was investigated in an animal model of acute myocardial infarction for its potential to provide contrast enhancement of the peri-infarct zone using magnetic resonance (MR) imaging. Radiotracer studies compared the biodistribution of soluble 59Fe-PyP with 99mTc-PyP in excised tissue samples. Preferential localization of 59Fe-PyP in the peri-infarct zone was found to be similar to 99mTc-PyP. The ratio (percent dose/gram of tissue) at the edge of the infarct to normal tissue was 1.30 +/- 0.16 and 1.44 +/- 0.33 for 99mTc-PyP and 59Fe-PyP, respectively. In initial studies with high doses of the contrast agent, gated T1-weighted MR images of animals with 48-hour-old infarcts were obtained at 15-minute intervals after injection of Fe-PyP at a dose of 350 mg/kg. Contrast enhancement of the infarct zone was observed in all studies and was maximal 15-30 minutes after injection. Signal intensity ratios (infarct/normal) increased from a baseline 1.31 +/- 0.22 to a peak 1.90 +/- 0.57. Studies were then performed with smaller amounts of Fe-PyP. Images obtained with 50 mg/kg Fe-PyP showed contrast enhancement beginning at 60 minutes. Toxicology studies showed primarily respiratory effects, which became significant at doses of 190 mg/kg. These preliminary studies suggest that Fe-PyP potentially could serve as an MR contrast agent to localize and size acute myocardial infarcts; however, its clinical use may be limited by potential toxicity and dose limitations.

Determination of malignancy of thyroid nodules with positron emission tomography.

BACKGROUND: Current noninvasive evaluation techniques of thyroid nodules are nonspecific. We studied the use of a new noninvasive imaging modality, positron emission tomography (PET), in the evaluation of thyroid nodules. METHODS: Nineteen patients were studied before operation with PET with [18F]-2-deoxy-2-fluoro-D-glucose (FDG). Twelve patients had solitary thyroid nodules and seven had multinodular goiters. Fourteen overlapping transverse slices were acquired through the thyroid gland. A region of interest was drawn around the abnormal area and the maximum pixel value was calculated and corrected to produce a normalized value for FDG uptake. RESULTS: Four of the 12 nodules were malignant (three papillary and one follicular carcinoma), with the others being follicular adenomas. All of the multinodular goiters were benign. All of the malignancies had an FDG greater than 8.5 and all of the benign nodules had an FDG less than 7.6. The dose uptake ratio of FDG was 10.8 +/- 3.2 (mean +/- SD) for the malignancies and was significantly greater than the dose uptake ratio of either the follicular adenomas (4.3 +/- 2.0) or the dominant nodule in multinodular goiters (3.0 +/- 2.0). CONCLUSIONS: The FDG uptake as measured by PET scanning successfully discriminated between all benign and malignant tumors. This technique appears useful in the evaluation of thyroid nodules.

CT of the normal pituitary stalk.

A prospective study assessed the size and frequency of visualization of the normal pituitary stalk on high-resolution computed tomography (CT). The normal pituitary stalk can be seen on the vast majority of high-resolution scans obtained with thin sections and intravenous contrast material. The upper size limit of the normal pituitary stalk is 4 mm at the level of the dorsum sellae and 4.5 mm above the dorsum. Stalks larger than this should be viewed with suspicion. Comparison of the size of the pituitary stalk with that of the nearby basilar artery is possible on most CT scans, providing a convenient and reliable visual check of the size of the stalk.

Cost-effectiveness of emergency intraarterial intracerebral thrombolysis: a pilot study.

PURPOSE: To assess the clinical efficacy and cost-effectiveness of emergency thrombolysis as a treatment strategy for thromboembolic intracerebral events. METHODS: Thirty-four patients with symptoms suggestive of middle cerebral artery occlusion were included. Eight of these patients were treated with intraarterial urokinase. Effectiveness was determined by comparing the admission National Institutes of Health stroke score to the 24-hour National Institutes of Health stroke score. The cost and length of stay of both populations were derived and used as measures of direct cost. The likelihood of admission to extended care facilities and estimated length cost of admission was used as a measure of indirect cost. RESULTS: The control population became slightly worse, with a change in National Institutes of Health score of -0.5, whereas the treated population improved slightly, with a change in National Institutes of Health score of +5.12. Analysis of the direct costs data between the two populations revealed a slight increased mean for the treated population ($15,202) as compared with the control population ($13,478). The unpaired t test, however, revealed no significant cost difference between the two groups. By reducing the number of completed strokes by one third or by decreasing the severity by the same factor (as shown in our study), the likelihood of admission to an extended nursing facility also is decreased. The cost saving per patient from extended care facilities is approximately $3435. CONCLUSION: The emergency application of intraarterial thrombolysis with urokinase results in a statistically significant positive change in National Institutes of Health score by at least five points. A statistically significant benefit is realized through the use of intraarterial urokinase. A statistically insignificant additional cost is shown by this study. This insignificant cost is more than offset by the saved nursing home costs.

Assessment of the effects of ciprofloxacin and nalidixic acid on cerebral blood flow and metabolism in healthy subjects by positron emission tomography.

STUDY OBJECTIVES: The mechanism by which the fluorinated quinolones produce central nervous system effects is unknown. Using positron emission tomography (PET), we evaluated the effects of two quinolones on brain blood flow as well as on oxygen and glucose metabolism. These determinations were done in conjunction with ophthalmologic and neuro-ophthalmologic testing. DESIGN: Randomized, double-blind, placebo-controlled, 7-day course of ciprofloxacin 750 mg (C750) or 500 mg (C500) every 12 hours, or nalidixic acid (NA) 1 g every 6 hours. POPULATION: Twenty-four healthy male volunteers, six in each treatment arm. RESULTS: [table: see text] CONCLUSIONS: Compared with baseline values, NA significantly reduced brain glucose uptake, whereas C500, C750, and placebo produced no detectable effect. No compound significantly altered brain blood flow or oxygen metabolism compared with baseline or other treatments. No significant effect on electroretinographic, electro-oculographic, or other neuro-ophthalmologic tests was observed.

Comparative assessment of the effect of lomefloxacin, ciprofloxacin, and placebo on cerebral blood flow, and glucose and oxygen metabolism in healthy subjects by positron emission tomography.

The mechanism by which the fluorinated quinolones produce central nervous system (CNS) effects is currently unknown. We measured the effect of lomefloxacin on cerebral blood flow and metabolism using positron emission tomography. Eighteen healthy, nonsmoking volunteers were randomized to receive lomefloxacin 400 mg, ciprofloxacin 750 mg, or placebo given in a single-blind fashion every 12 hours for 72 hours, the time window for maximum lomefloxacin CNS effects. Subjects receiving lomefloxacin had a mean (+/- SEM) cerebral blood flow (CBF) of 46 (2.9) ml/min/100 g, glucose metabolism (FDG) 4.7 (0.4) mg/min/100 g, oxygen metabolism (OM) 3.3 (0.3) ml/min/100 g, and oxygen extraction (%OM) 0.4 (0.04). Posttreatment values were 43 (3.6) ml/min/100 g, 4.2 (0.4) mg/min/100 g, 2.6 (0.3) ml/min/100 g, and 0.4 (0.03), respectively. Values for subjects receiving ciprofloxacin were CBF 44.8 (1.6) ml/min/100 g, FDG 4.9 (0.7) mg/min/100 g, OM 4.1 (0.4) ml/min/100 g, and %OM 0.6 (0.03) at baseline, and 40.3 (3.5), 4.5 (0.6), 3.4 (0.4), and 0.5 (0.09), respectively, after treatment. For placebo-treated subjects, baseline values were CBF 41.4 (1.9) ml/min/100 g, FDG 4.9 (0.5) mg/min/100 g, OM 3.3 (0.4) ml/min/100 g, and %OM 0.5 (0.07), and respective posttreatment values were 42.1 (2.3), 5.0 (0.6), 3.5 (0.3), and 0.5 (0.02). No effect was observed on visual (qualitative), blinded reading of the scans. No significant effect on cerebral blood flow or metabolism was detected. We conclude that short-term administration of lomefloxacin or ciprofloxacin to healthy volunteers does not have a significant effect on cerebral blood flow, or on oxygen or glucose metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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.

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.

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.

Photopenic areas on bone scanning associated with childhood leukemia.

Photopenic areas on bone scintigraphy is a rare presentation of childhood leukemia. This includes the more common acute lymphocytic leukemia as well as the far less common myelomonocytic leukemia. Other causes of photopenia on bone scintigraphy in these patients include relapse with marrow replacement and associated bone necrosis. Methotrexate therapy has also previously been described as showing similar photopenic areas secondary to bone necrosis.

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.

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.

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.