Ionic iodinated contrast medium and amobarbital sodium mixtures: potential for precipitation

When a small amount of diatrizoate meglumine, an ionic iodinated contrast medium, is left in a catheter system before injection of amobarbital sodium or when the contrast medium is intentionally mixed with amobarbital sodium, a potentially dangerous situation occurs. The authors showed in vitro that a dense precipitate forms in this situation. This is due to an acid-base reaction between the relatively acidic contrast medium and basic barbiturate and the subsequent formation of insoluble amobarbital.

Factor analysis of regional cerebral glucose metabolic rates in healthy men

Cerebral glucose utilization measured with fluorine-18-fluoro-2-deoxy-D-glucose is characterized by considerable variability both among different persons and for the same person examined on different occasions. The goal of this study was to explore whether some regions of the brain were more variable than others with respect to glucose utilization and whether there was a pattern in their covariance. The global and regional cerebral utilization of glucose was measured in 12 healthy young volunteers on 3 or 4 occasions. In all, 24 regions were examined. The interrelation of the glucose utilization rates of the brain regions was investigated by factor analysis of the metabolic rates. Some 70% of the total variance was attributable to only 1 factor, while 80% of the total variance could be attributed to 2 factors. Regions making up the first factor were the frontal and temporal cortex, cingulate gyrus, caudate nucleus, thalamus and putamen. These regions are functionally related to the limbic system. Regions of the second factor were the parietal cortex, occipital cortex and cerebellum, regions more clearly related to sensory and motor functions. The 2-factor pattern was highly reproducible, being found with different algorithms for factor extraction and rotation. Under resting conditions, the variance of cerebral metabolism seems to be primarily related to regions which are closely involved with the limbic system. Cortical regions involved primarily in motor and sensory functions have less influence on the variance.

Biliary tract complications following laparoscopic cholecystectomy: imaging and intervention

Radiologic studies and interventional procedures were performed in a series of 13 patients with biliary complications following laparoscopic cholecystectomy, and the results were evaluated. Two categories of ductal complication--minor and major--were found. Minor complications (n = 6) included bile leaks and bilomas; these were managed with percutaneous techniques or simple surgical repair. Major complications (n = 8), consisting primarily of common hepatic duct injuries or strictures, were markedly resistant to percutaneous therapy, requiring major surgical repair (hepaticojejunostomy). Percutaneous treatment of recurrent strictures after primary repair was undertaken in three patients. Diagnostically, radionuclide imaging appeared most helpful in screening for biliary complications of laparoscopic cholecystectomy, supplemented by endoscopic retrograde cholangiopancreatography and/or percutaneous transhepatic cholangiography for definitive diagnosis.

A noninvasive test of sphincter of Oddi dysfunction in postcholecystectomy patients: the scintigraphic score

The ideal noninvasive test of sphincter of Oddi dysfunction (SOD) does not exist and the diagnosis of patients with postcholecystectomy pain often relies on invasive procedures. In this paper we describe a scintigraphic test for SOD: the scintigraphic score. This score combines quantitative and visual criteria for interpretation of hepatobiliary scans. Twenty-six consecutive postcholecystectomy patients underwent hepatobiliary imaging, ERCP, and sphincter manometry. Twelve patients had SOD and 14 had normal sphincters determined by clinical findings, ERCP, and manometric studies. All patients with normal sphincter had scores of 0-4, while patients with SOD had values of 5-12 for a perfect sensitivity and specificity of 100%. Hepatobiliary scans scored in this fashion may become the noninvasive test of choice to screen postcholecystectomy patients with suspected SOD.

The influence of biological and technical factors on the variability of global and regional brain metabolism of 2-[18F]fluoro-2-deoxy-D-glucose

This study investigated the influence of biological and technical factors on variations of global and regional cerebral metabolic rate of glucose (CMRglc) measured with 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG). Twelve male volunteers (22-40 years) were investigated on three or four occasions for a total of 42 studies. We calculated the variance/covariance of the following parameters: CMRglc, six parameters of the blood clearance of [18F]FDG, hour of injection, peak time of blood radioactivity, and six components of the operational equation (nonradioactive blood glucose concentration, brain radioactivity, two integrals, numerator, and denominator). There was correlation among these six components, except for nonradioactive blood glucose. However, the correlation between the CMRglc and the individual components of the operational equation was poor. The inter- and intrapersonal CMRglc coefficients of variations were 13.8 and 7.1%, respectively. In contrast, coefficients of variations of the numerator and denominator of the operational equation were 34.6 and 32.6%, respectively, and were always in the same direction. No correlation was found between CMRglc and the technical factors in the numerator and denominator of the operational equation. Factor analysis disclosed that a single factor was responsible for 70% of the variance. This factor included caudate, putamen, thalamus, frontal cortex, temporal cortex, and cingulate gyrus. These structures are involved with multiple complex functions, from autonomic motor control to behavior and emotions. The intrinsic metabolic variability of these structures, along with the basal metabolic processes that are continuously going on in the brain, may be the best explanation for the variance encountered in our investigation.

Failure of perchlorate to inhibit Tc-99m isonitrile binding by the thyroid during myocardial perfusion studies

The thyroid gland receives an average radiation dose of 3 rads during two Tc-99m isonitrile (MIBI) myocardial perfusion studies, if 20 mCi is administered both at rest and at peak exercise. In patients with coronary artery disease, multiple myocardial perfusion studies may be required, resulting in a high level of thyroid radiation. We attempted to reduce this radiation exposure by blocking thyroidal Tc-99m MIBI uptake with oral potassium perchlorate (KCIO4). Fourteen normal subjects received 0.6g to 0.8g KCIO4 20-25 minutes before tracer injection. Subjects who received KCIO4 at rest (n = 11) did not receive KCIO4 at their stress study, and vice versa (n = 3). Thyroid uptake values were obtained with a thyroid probe 20 minutes after injection for both rest and stress studies and were corrected for saturation effects. There was no difference between fractional thyroid uptake values with and without preceding perchlorate administration: 1.9 +/- 0.5% and 1.8 +/- 0.3% (mean +/- SD), respectively. Failure to block Tc-99m MIBI uptake after intravenous (IV) injection is probably due to high thyroidal blood flow and nonspecific tracer accumulation. The concentration of this radioisotope in adjacent muscles also contributes to the high thyroid radiation dose. In summary, administration of KCIO4 before Tc-99m MIBI studies does not reduce the thyroidal radiation dose or uptake of this tracer, suggesting that thyroidal uptake of this tracer is not mediated by the iodine trapping mechanism.

Global and regional cerebral metabolic rate of 2-[18F]fluoro-2-deoxy-D-glucose in the presence of ofloxacin, a gamma-aminobutyric acid a receptor antagonist

We investigated the effects of ofloxacin, a new antibacterial quinolone gamma-aminobutyric acid A receptor antagonist, on the global and regional cerebral metabolic rates of glucose (cMRgl). Twelve healthy normal male volunteers (mean age, 26.7 years) were studied in a double-blind, placebo-controlled protocol of 11 days' duration. Results of a total of 42 positron emission tomography studies were obtained for these subjects: 12 base line, 18 during placebo, and 12 during ofloxacin administration. The conditions under which repeat positron emission tomography studies of the same subject were performed were reproduced as closely as possible. cMRgl was measured in 24 brain regions. The global cMRgl for base line, placebo, and ofloxacin were 8.82 +/- 1.17, 8.24 +/- 1.17, and 8.79 +/- 1.18 mg/min/100 g, respectively (mean +/- 1 standard deviation). The mean global differences between base line and placebo and between ofloxacin and placebo were 5.1 and 6.6%, respectively. Analysis of variance of both the global and the regional cMRgl showed no statistical difference between base-line, placebo, and ofloxacin studies. Variations in cMRgl found in this study were not related to the presence of ofloxacin. Results of our study demonstrate that ofloxacin does not increase or decrease cMRgl beyond the limits of variability of the study.

Sonographic diagnosis and grading of Hashimoto's thyroiditis

There is no ideal test for the diagnosis of Hashimoto's thyroiditis (HT). The purpose of this study was to determine the type of information sonography provides in these patients. In 47 cases of HT we identified four distinct sonographic patterns which correlated with degree of disease severity. The higher patterns had larger glands, higher antithyroid antibody titers, lower T4 and higher TSH levels, and higher incidence of hypothyroidism. With sonography we were able to suspect the diagnosis in patients with goiter of unknown etiology, to measure gland size, identify patients with functional impairment, and predict which patients required treatment. No other single test provides so much information in patients with HT.

Bowel visualization during indium-111-labelled diethylene triamine penta-acetic acid cisternography due to massive cerebrospinal fluid leak. Case report and review of the literature

We report a case of massive cerebrospinal fluid (CSF) leakage where the tracer injected intra-thecally for radionuclide cisternography was later visualized in the bowel as well as the nasopharynx. We discuss the potential implications of this finding in patients with CSF leaks. A brief review of the diagnosis of CSF leaks is included.

Gallium imaging of esophageal carcinoma: increased sensitivity with lateral views of the thorax

Ga-67 imaging has not been very successful in the detection of esophageal carcinoma. In most reports, sensitivity for the primary tumor ranged from 25-61%, but imaging had been done only in anterior and posterior (A-P) projections. We performed gallium scans in 30 patients with esophageal carcinoma, adding lateral views to the routine A-P projections, to study the effect of lateral views on tumor detection. The A-P views detected only 57% of the tumors while the right lateral visualized 89%, and the left lateral detected 100%. Some lesions may be hidden by the sternum and the spine in the routine A-P views. Previous disappointments with Ga-67 imaging of esophageal carcinoma were probably due to this technical factor. Being gallium-avid, esophageal tumors deserve further studies with this agent to determine the role of Ga-67 imaging in this condition. These studies should be performed with multiple views of the thorax or, better yet, with SPECT imaging of the chest, to circumvent the problem of sternum and spine interference.

Dual-tracer scintigraphy and subtraction studies in the diagnosis of hepatocellular carcinoma

Dual tracer scintigraphy (DTS) (technetium 99m [99mTc] sulfur colloid and gallium 67 citrate [67 gallium citrate]) of the liver and computer subtraction studies (SS) were performed in 26 patients subsequently proven to have hepatocellular carcinoma (HCC) and 32 patients with cirrhosis and focal defects on the colloid scan, with no evidence for HCC after a complete evaluation and a 2-year follow-up period. Both DTS and SS had a sensitivity of 96% and a specificity of 90.6% for HCC. There were three false positive cases (9.4%), two of which were occult abscesses. The predictive value of a positive test was 89% and that of a negative test was 97%. The smallest tumor detected measured 2 cm in diameter and was only visualized with the SS. In the clinical setting, when HCC is suspected (a situation in which tumors are usually larger than 2 cm and the pretest probability of disease is between 20% and 60%) the DTS and SS is an excellent test for the diagnosis or exclusion of HCC. It does not appear to have a role in screening programs.

The various scintigraphic patterns of Warthin's tumor

The authors' experience with salivary gland imaging in patients with Warthin's tumor was reviewed and the scans correlated with the pathologic findings of each tumor in an attempt to explain the scintigraphic variants found. Most Warthin's tumors show increased perfusion on imaging. The predischarge static images have a low sensitivity, detecting only 33% of the tumors. Warthin's tumors may appear hot, warm, or cold on the predischarge images but invariably become hot in the postdischarge study, for a 100% sensitivity. Many tumors reveal internal warm or cold areas. These focal defects correlate well with the presence of intratumoral cysts. The presence of these mixed lesions should not lead the physician away from the diagnosis of Warthin's tumor.

Liver scintigraphy in chronic hepatosplenic schistosomiasis. A predictor of disease severity

Liver-spleen scintigrams were performed in 42 patients with chronic hepatosplenic schistosomiasis. The scan patterns found are described and classified in five stages of increasing hepatic involvement. The scintigraphic classification correlates well with clinical parameters of disease severity. With higher stages, the number of symptoms and the severity of complications increase. The liver-spleen scan provides a simple and accurate means to determine extent of hepatic involvement and probabilities of complications in this disease.

A visual index of thyroid function

A visual index of thyroid uptake (VITU) is introduced as a qualitative measure of thyroid trapping. This index is determined from the 20-minute 99mTc-pertechnetate scan by visually comparing the relative tracer uptake between the thyroid and salivary glands. Three categories are defined: low, normal and elevated. The VITU correctly identified the functional status of the thyroid in 94% of 123 patients studied and agreed with the 24-hour radioiodine uptake (RAIU) in 89%. The VITU is a very simple but highly accurate, reliable and reproducible test. It was primarily designed to complement other tests of thyroid function by contributing qualitative information about the thyroidal trapping mechanism, but it can also be useful in confirming blood tests of thyroid function in cases in which one would prefer to avoid 131I administration for RAIU studies.

Thyroid scintigraphy: pinhole images versus rectilinear scans

99mTc-pertechnetate thyroid scintigraphy was performed on 67 patients with a pinhole camera and a rectilinear scanner. The dual set of images was interpreted blindly by four nuclear medicine physicians. Observer performance with each of the two imaging techniques was evaluated by the receiver operating characteristic (ROC) method and by multivariate information analysis (MIA). Performance was superior for the four observers when interpreting the pinhole images, identification accuracy ranging from 70 to 94% with the pinhole images and only 49 to 63% with the rectilinear scanner.

Bony lesions in systemic mastocytosis: scintigraphic evaluation

Bone, bone marrow and gallium citrate Ga 67 scans were performed on a patient with systemic mastocytosis and bony involvement to evaluate their diagnostic value in such patients. The bone scan revealed increased tracer concentration in the involved areas. These abnormalities were less prominent than those on the roentgenograms, suggesting that only a part of the roentgenographic abnormalities were associated with reactive bone formation. Bone scanning may be less sensitive than roentgenograms to detect the full extent of the bony lesions of systemic mastocytosis. The bone marrow scan revealed a normal central marrow with peripheral marrow expansion. Possibly, the central marrow infiltration by mast cells was sufficient to interfere with its hemopoietic function to a degree that made it necessary to reactivate peripheral marrow tissue. There was no significant 67Ga accumulation in the bony lesions of systemic mastocytosis.