Prospective localization of epileptogenic foci: comparison of PET and SPECT with site of surgery and clinical outcome.

PURPOSE: To correlate prospective imaging findings in patients with intractable partial epilepsy with site of surgery and clinical outcome. MATERIALS AND METHODS: Thirty-five patients (25 male, 10 female) underwent positron emission tomography (PET; n=25), interictal single photon emission computed tomography (SPECT; n=33), or postictal SPECT (n=23) for localization of epileptogenic foci. The standard of reference was site of surgery. RESULTS: Sensitivity was 60%, 61%, and 52%; positive predictive value was 83%, 71%, and 55%; and localization was incorrect in 12% (three of 25 cases), 24% (eight of 33 cases), and 43% (10 of 23 cases) in PET, interictal SPECT, and postictal SPECT, respectively. There was no statistically significant difference in localization capabilities in a comparison of interictal SPECT and PET (correct localization, P=.999; incorrect localization, P=.625). There was a trend toward higher incorrect localization with interictal SPECT. CONCLUSION: Postictal SPECT has low sensitivity and a high incorrect localization rate and should not be performed in these patients. Interictal SPECT with 6-8-mm full-width at half-maximum is an alternative to PET. However, the trend toward higher false-localization rates must be taken into consideration.

Regional distribution of 2-deoxy-2[18F]-fluoro-D-glucose for metabolic imaging using positron emission tomography.

Radiopharmaceutical availability is one of the reasons dissemination and growth of clinical PET imaging remains problematic. A 'regional' cyclotron-radiopharmacy facility for the production of the positron emitting radionuclide 2-deoxy-2[18F]-fluoro-D-glucose (FDG), has been operational for over 2 years and supplies this radiopharmaceutical to five camera facilities, four distant and one on-site. The RDS 11 MeV cyclotron is capable of dual bombardment of targets yielding 60 GBq (1600 mCi) of F-18 in a 90 minute period. F-18 labelled FDG is produced by an automated synthesis module yielding 22.2 GBq (600 mCi) FDG. The PET radiopharmacy is required to perform extensive quality assurance activities including a number of tests to insure final product and safety. [18F]FDG is shipped in unit dose vials, 6 ml, two per shielded container, meeting Department of Transportation (DOT) specifications (43 x 43 cm cubes, styrofoam packing, 22 lb. lead shield). This adheres to regulations requiring no more than 200 millirem per hour (mR/Hr) exposure at the container surface, and 10 mR/hr at a distance of 1 meter. Total transport time, utilizing private air and ground couriers, to distant facilities is approximately 100-120 minutes. Based on patient scheduling and protocol used, allowing 45-60 minutes between dose administrations, and availability of 22.2 GBq (600 mCi), 20-22 unit doses can be supplied, divided and shipped in a number of ways. The regional-commercial distribution of PET radiopharmaceuticals, specifically [18F]FDG, is feasible. This provides availability of metabolic imaging at sites distant to radiopharmaceutical production.

Positron emission tomography in clinical practice.

Positron emission tomography (PET) has been considered a research tool; however, advances in hardware and software, along with availability of small medical cyclotrons, make clinical metabolic imaging feasible. There is accumulating data, especially in the areas of neurology and cardiology, to support its use in the appropriate clinical setting and patient population.

Soft tissue hematoma as a cause of fever in the adult.

Hematoma as an isolated cause of temperature elevation in adult patients is rarely reported. We describe a patient with a large hematoma involving his right leg that caused significant pyrexia. The computerized axial tomography findings are discussed, as well as the possible mechanisms responsible for the temperature elevation.

Asymptomatic pulmonary embolism. A common event in high risk patients.

Ventilation and perfusion lung scans were obtained before and at weekly intervals following hip surgery or major amputation in 158 patients. Pulmonary arteriograms were obtained in 21 of 33 patients developing perfusion patterns strongly suggesting embolism; 19 of the 21 arteriograms demonstrated pulmonary embolism. From autopsy and clinical data, 36 patients were diagnosed as having an embolus while under study, and 12 patients were suspected of having had an embolus during their illness but prior to entry into the study. Only four of these 48 patients experienced symptoms suggestive of pulmonary embolism. We conclude that asymptomatic pulmonary embolism is a common event in the populations studied.

Ultrasound measurement of contraction response of the gallbladder: comparison with the radionuclide test for cystic duct patency.

Two tests of cystic duct patency were compared in 37 patients with suspected acute cholecystitis. Ultrasound (US) measurement of gallbladder contraction induced by 40 Ivy dog units of cholecystokinin (CCK) was followed by the radionuclide (RN) test for cystic duct patency. In all 13 patients in whom US showed significant gallbladder contraction after CCK, the cystic duct was proved to be patent by the RN test. The gallbladder did not contract significantly in 24 patients. Eleven of these patients had acute cholecystitis, with evidence of cystic duct obstruction, and 12 had patent cystic ducts and final diagnoses other than acute cholecystitis. The measurement of contraction of the gallbladder in response to CCK is a valuable improvement over simple US when cystic duct obstruction is excluded; failure of contraction is not specific, and independent evaluation of cystic duct patency is required.

Rapid radiometric method for determining drug susceptibility of Mycobacterium avium-intracellulare.

A rapid radiometric method for susceptibility testing of Mycobacterium avium-intracellulare to eight chemotherapeutic agents was compared with a conventional method. Results were available within 72 h by radiometric testing in contrast to 21 days by the conventional method. The radiometric and conventional methods agreed to 61% of the tests, but growth inhibition of greater than or equal to 50% was detectable only by radiometric testing in an additional 36.5% of the tests. In only 2.5% of the tests was the radiometric method unable to detect complete inhibition shown by the conventional method. Quantifiable increases in inhibition with increasing concentration of isoniazid were more frequently detectable by the radiometric method than by conventional testing. The radiometric method is a simple, rapid, and quantitative test for drug susceptibility of mycobacteria and warrants further investigation.

Bone scintigraphy in trauma of the hand and wrist.

Bone scintigraphy utilizing Tc-99m phosphate compounds was valuable in the diagnosis of injuries of the hand and wrist in three patients in whom conventional roentgenograms and other investigations over several months were inconclusive. With appropriate patient selection, either positive or negative scans may be helpful in assessing trauma to the hand or wrist. Full clinical evaluation is necessary for accurate interpretation of hand and wrist bone scintigraphy in order that potential causes of false positive or false negative studies may be recognized.

Computer-assisted liver-mass estimation from gamma-camera images.

We have devised a computer-assisted method for objective estimation of liver mass from the right lateral projection of radiocolloid images of the liver. Gamma-camera images were digitized, preprocessed, and stored in computer memory. The definition of liver for area measurement was adaptively determined by means of a Laplacian operator that measures change in radioactivity slope associated with the liver margin. Individual thresholds were calculated for each of 16 subregions. A liver-mass index was derived from a linear regression model correlating the area of the right lateral projection with liver weight at autopsy in 50 patients whose livers weighed between 0.8 to 3.0 Kg. The correlation coefficient found for this method was 0.83 using the equation: Liver Mass [kg] = Area [cm2]/275 [kg/cm2]--0.215 [kg]. Liver-mass estimates using an alternative computer-assisted method or representative manual methods adapted for gamma-camera images showed lower correlation with liver weight at autopsy.

Failure of low dose heparin to prevent pulmonary embolism after hip surgery or above the knee amputation.

In a randomized, double-blind trial, 5,000 USP units of sodium heparin or saline were give subcutaneously at least two hours before surgery and at 12 hour intervals thereafter to patients requiring total hip replacement, surgical correction of hip fracture, or major lower extremity amputation for vascular insufficiency. Lung perfusion scans were performed before surgery and at weekly intervals during the postoperative period. Pulmonary arteriograms were requested in patients developing new perfusion defects on serial scans. Two hundred twelve patient hospitalizations were analyzed. We diagnosed acute pulmonary embolism by serial lung perfusion scans or at autopsy in 37 patients. The incidence of pulmonary embolism in 40 patients with below the knee amputation was too low to warrant conclusions. The incidence of acute pulmonary embolism in 94 patients undergoing above the knee amputation was 25% in patients receiving heparin and 27% in patients receiving saline. The incidence of acute pulmonary embolism in 78 patients undergoing hip surgery was 13% in patients receiving heparin and 12% in patients receiving saline. We conclude that the regimen used had no significant effect on the incidence of acute pulmonary embolism in patients undergoing hip surgery or above the knee amputation.

Widespread abnormalities of radiocolloid distribution in patients with mycopolysaccharidoses.

Mucopolysaccharidoses (MPS) are inherited disorders of lysosomal enzymes. We have examined the sites of accumulation of intravenously injected 99mTc-sulfur colloid in order to assess the regional distribution of phagocytic function in ten patients with MPS: three with Type VI (Maroteaux-Lamy). Increased lung uptake was observed in 22 of 40 studies (55%) on the five patients with MPZ Type II but in none of the 38 studies on patients with other MPS types. All MPS patients had diffuse recticuloendothelial (RE) marrow hypoplasia, despite normal or nearly normal hematocrits and hemoglobin levels, suggestion dissociation of the phagocytic and erythropoietic elements of the marrow. The eight patients with MPZ Types I and II all had hepatomegaly and increased splenic uptake. Seven of these patients with MPS Types III and VI did not have hepatosplenomegaly. These studies indicate that the lysosoma enzymic defect of MPS results in widespread abnormalities of the distribution of phagocytic function in the liver, spleen, bone marrow, and probably the lung as well.