Validation of Fourier amplitude ratio to quantitate valvular regurgitation.

It has previously been shown that patients with valvular regurgitation can be identified by the ratio of left and right ventricular amplitude values obtained from first harmonic Fourier analysis of the gated blood pool scan. The present study was designed to validate the accuracy of this technique for quantifying the amount of valvular regurgitation. In a blinded analysis of 19 patients who underwent cardiac catheterization, there was a close correlation between the radionuclide and hemodynamic determination of the amount of regurgitation (r = 0.84). The interobserver agreement for calculating the radionuclide data was also high (r = 0.88). These results suggest that the Fourier ventricular amplitude ratio is an accurate and reproducible technique for quantifying valvular regurgitation by gated blood pool scanning.

Limited weight losses with a gastric balloon.

An evaluation of the Garren-Edwards gastric bubble in the treatment of obesity was done. Several clinical trials have compared the effects of behavior therapy with and without the bubble, but the effects of the bubble alone have not been previously evaluated. Ten obese women averaging 91% overweight received the bubble without adjunctive therapy during a 12-week treatment period. Frequent psychological and laboratory measures as well as weight were obtained during the study to explore the possible mechanisms of the bubble's effect and its side effects. Mean weight change was -2.5 kg, with a range of -8.8 to +1.6 kg. Four patients lost more than 3.5 kg, three lost less than 3.5 kg, and three gained weight. The Garren-Edwards gastric bubble alone does not appear to provide significant benefit to most obese patients.

Pulmonary scintigraphy in a patient with multiple pulmonary arteriovenous malformations and pulmonary embolism.

The scintigraphic findings in a patient with multiple pulmonary arteriovenous malformations (AVMs) complicated by superimposed pulmonary embolism are reported. Although pulmonary AVMs may cause small subsegmental scintigraphic abnormalities, the demonstration of perfusion defects which are segmental or larger should strongly suggest the presence of superimposed pulmonary embolism in a patient with multiple pulmonary AVMs.

Urine extravasation into the scrotum.

A case report demonstrating urine extravasation into the scrotum following renal transplantation is presented. An anatomic explanation of the pathway of urine drainage into the scrotum is offered with a brief discussion of extravasation following renal transplantation and its detection by scintigraphy.

The effect of meal energy content on gastric emptying.

Gastric emptying (GE) has been reported to be influenced by meal weight (grams) and composition (% carbohydrate:protein:fat) but the effect of meal energy content (kcal) on gastric emptying, independent of composition, has not been thoroughly investigated by scintigraphic techniques. In order to determine the effect of caloric content on GE, 12 normal male volunteers, ranging in age from 19-28 yr (mean = 24 yr), had GE scans (n = 32) performed with a solid meal of fixed composition (carbohydrate 40%:protein 40%:fat 20%) but varying energy content [150 kcal (n = 9), 300 kcal (n = 14), and 600 kcal (n = 9)]. Increasing the energy content of the meal of fixed composition progressively delayed gastric emptying: T1/2 = 57', 70', and 95' for 150 kcal, 300 kcal and 600 kcal, respectively (p less than 0.05; Student's t-test). Reproducibility, evaluated by performing GE scans (n = 8) on different days in the same individual (n = 4) with the same meal (300 kcal), was good (r greater than or equal to 0.89). Variability varied inversely with meal energy content (CV:150 kcal greater than or equal to 300 kcal and 600 kcal). The 300 kcal mean seems to be the best compromise since it results in less intersubject variability than 150 kcal, has minimal intrasubject variability, but is not as prohibitively large as the 600 kcal meal.

Bronchobiliary fistula detected by cholescintigraphy.

We present a case of a bronchobiliary fistula initially detected by hepatobiliary scintigraphy. The patient developed bilioptysis 18 mo after undergoing a right hepatic lobectomy and resection of the common bile duct for cholangiocarcinoma. The procedure was complicated by the development of a subphrenic abscess that required percutaneous biliary drainage.

Effect of the Garren-Edwards gastric bubble on gastric emptying.

The Garren-Edwards Gastric Bubble (GEGB) was introduced in 1984 as an alternative to surgery (jaw wiring, gastrointestinal bypass, vertical banded gastroplasty) for the treatment of morbid obesity in patients who had failed behavior modification therapy or dietary management for weight reduction. Its mechanism of action is unclear and previous reports have not demonstrated any significant consistent alteration in gastric emptying (GE) as measured by radionuclide techniques. Other proposed mechanisms include: placebo, hormonal, mechanical "satiety", behavioral modification, and neuronal. In order to determine the effect of the GEGB on GE, ten obese (mean % overweight = 89%) patients, 27-50 yr old (mean = 36 yr), had solid GE scans before and 5 wk after endoscopic placement of the bubble. GE scans were performed in six patients after removal (12 = wk residence time). The meal consisted of 300 microCi [99mTc]sulfur colloid in the form of a 300 kcal egg sandwich (egg white 248 g, white bread 40 g, butter 6 g; composition = CHO 40:PR 40: FAT 20) with 180 ml deionized water. Images were obtained in the anterior and posterior projections at 15-min intervals for 1 hr (four patients) or 2 hr (six patients) and the %GE (decay corrected geometric mean) was calculated. Unlike other studies involving the GEGB, adjunctive therapy in the form of dieting and behavior modification were not employed in this study. The effect of the GEGB alone in the treatment of obesity has not been previously evaluated. There was a significant (p less than 0.025) delay in gastric emptying at 1 hr (pre-bubble mean % gastric retention = 46%; bubble mean = 57%; n = 10). After removal, GE returned toward baseline (mean % gastric retention = 51%; n = 6) (p less than 0.05) (Student's t-test). The average weight loss was 5.5 lb (n = 10; p less than 0.025). One mechanism of action of the GEGB may be delayed gastric emptying resulting in early satiety and decreased food intake with resultant weight loss.

Localization of pheochromocytoma: MIBG [correction of MIGB], CT, and MRI correlation.

Nineteen patients (8 M, 11F) ranging in age from 15 - 67 yr old (mean = 39 yr) with clinically diagnosed pheochromocytomas were prospectively evaluated with 131I metaiodobenzyl-guanidine (MIBG) scintigraphy (n = 19), computed tomography (CT) (n = 19), and magnetic resonance imaging (MRI) (n = 17) in order to determine their relative diagnostic efficacy. Pathologic confirmation was obtained in all 19 patients: 13 intraadrenal and six extraadrenal with metastases in five (Table 1). All three imaging modalities were in agreement in 11 of 14 completed examinations (79%). MIBG and CT agreed in 16 of the 19 patients in whom both were performed (84%). MIBG/MR and CT/MR results were concordant in 12 of 14 (86%) and 13 of 14 (93%) jointly completed examinations, respectively. There was one false-negative (FN) MIBG scan, two FN CT scans, and one FN MR scan. MIBG, CT, and MRI are complementary procedures with MIBG providing more specific functional information and the latter two superior anatomic detail. MIBG scintigraphy is recommended as the initial localizing study of choice (especially for the detection of extraadrenal disease and postoperative recurrence), as a guide for CT and/or MR and specific functional confirmation of their findings. Although MRI is capable of imaging in multiple planes (without exposure to ionizing radiation or the need for i.v. contrast material) with superior contrast compared to CT, it is expensive and has poor patient cooperation. However, it may be capable of differentiating pheochromocytomas from other adrenal masses on the basis of signal characterization.

Infectious imaging with indium-111-labeled nonspecific polyclonal human immunoglobulin.

Nonspecific polyclonal immunoglobulin (IgG), prepared from pooled human serum gamma globulin and labeled with 111In has been reported to be equivalent to antigen-specific antibody in the detection of focal infection or inflammation during the first 24 hr after injection. We describe our experience in a Phase II clinical study using 111In-IgG in 15 patients (8 males, 7 females) ranging from 26 to 80 (mean = 50) yr of age with suspected focal infection/inflammation. Pathologic confirmation was obtained in 5/15 cases. A combination of clinical course, laboratory results, and other imaging procedures were used to categorize the other 10 patients. One possible false-negative involved a presumed aspiration pneumonia in a patient with a history of aspiration, bibasilar infiltrates on chest film, and no other identified source of infection. Otherwise, there were 10 confirmed positives, 4 confirmed negatives, and no false-positives. Our findings confirm earlier reports that 111In-IgG may be a superior imaging agent for infection/inflammation with practical advantages over 67Ga-citrate and 111In-labeled leukocytes.

Indium-111-labeled white blood cells in the detection of osteomyelitis complicated by a pre-existing condition.

Forty-six patients (23M, 23F) ranging in age from 19 to 79 yr with a clinical history of a nonunion fracture, surgery, diabetes or a soft-tissue infection were studied with [111In]oxine WBCs to detect osteomyelitis. There were 27 true-positive, nine true-negative, two false-positive and one false-negative. The false-positives and the false-negative occurred in patients with soft-tissue infections overlying the area of interest. All diagnoses were confirmed by intraoperative bone biopsies and cultures. Bone biopsy and scan were performed within 2 days of each other in 39 patients. The overall sensitivity was 97% (27/28), specificity, 82% (9/11) and the diagnostic accuracy, 92% (36/39). The remaining seven patients had negative [111In]WBC scans several months after positive bone biopsies and definite antibiotic treatment. This suggests that [In]WBC scans become negative after appropriate therapy is undertaken. Interobserver data was obtained from four nuclear physicians of varying experience blinded to clinical information. A high degree of agreement was found in over 90% of the cases. This study demonstrates the utility of [111In]WBC scans in the diagnosis and follow-up of complicated osteomyelitis and a high level of interobserver agreement in scan interpretation.

Fourier amplitude ratio: a new way to assess valvular regurgitation.

The stroke-volume ratio determined from the equilibrium gated blood-pool study has been utilized to assess valvular regurgitation, but it is difficult to get reproducible results using generally available equipment. We have developed a new approach utilizing the Fourier amplitude ratio of the left and right ventricles, which is easily implemented and reproducible. Initial clinical experience shows that 17 patients with valvular regurgitation were clearly distinguished from 30 patients without valve disease.

Bone scintigraphy: differentiating benign cortical irregularity of the distal femur from malignancy.

Two cases of benign cortical irregularity of the distal femur ( BCIDF ), which radiologically simulate malignancy, are presented. The use of bone scintigraphy in differentiating this entity from malignancy is described.

In vivo SPECT imaging of CNS D-2 dopamine receptors: initial studies with iodine-123-IBZM in humans.

Iodobenzamide (IBZM) is a D-2 dopamine receptor antagonist. In this paper the results of Phase I clinical studies of iodine-123-(123I)IBZM in humans are reported. Preliminary imaging studies, both planar and single-photon emission tomography (SPECT), of no-carrier added [123I]IBZM in humans show specific localization in the basal ganglia of the brain. At 2 hr after an i.v. injection, the brain uptake was 3.72% of the dose, and at 20 hr later the uptake diminished to 0.7%. Radiation dosimetry calculation indicated that the radiation dose to the brain was minimum, 0.039 rad/mCi, while the large intestine wall received the highest dose, 0.28 mrad/mCi. The radiation dosimetry and pharmacology data suggest that this agent is safe for human use.

Sources of variability in quantitative thallium analysis.

Nineteen patients undergoing exercise thallium scanning had two separate redistribution 40 degree LAO acquisitions obtained; the gamma camera was repositioned between the views. Data were analyzed by generating 60-point circumferential profile curves for each of the 38 images and the variability of individual points and 18 degrees and 36 degrees segments was determined. Intraobserver variability, assessed by reanalyzing the scans one week later, was approximately 5.0%. The interobserver variability was of similar magnitude (approximately 6%). The total reimaging variability was, however, significantly larger (approximately 13%). It is concluded that quantitative image analysis is highly reproducible with low intra- and interobserver variabilities, but the act of repositioning and reimaging introduces significant additional variability. This may limit the ability of quantitative thallium scanning to document changes in the size of defects.

Radionuclide imaging of the urinary tract.

This article describes the role of nuclear medicine in the evaluation of the genitourinary tract. The technical aspects of radionuclide imaging (radiopharmaceuticals, radiation dosimetry, instrumentation, and method) are briefly presented, and each of the indications for renal scintigraphy--including the evaluation of differential renal function, hypertension, obstruction, renal transplants, masses, trauma, congenital anomalies, vesicoureteral reflux, and infection--are discussed. The relative advantages and disadvantages of radionuclide imaging with respect to alternative radiographic examinations (such as intravenous urography, ultrasonography, CT, angiography, and magnetic resonance imaging) are emphasized wherever applicable.

False-positive liver scan due to ascites.

Extrahepatic structures (breast, costal margin, kidney, pleural effusion, right lower lobe lung mass) may occasionally result in a false-positive liver scan by causing attenuation of the gamma rays emenating from the liver, thereby simulating an apparent intrahepatic lesion. A false-positive diagnosis of intrahepatic pathology may often be avoided by simple maneuvers such as elevating the breast, obtaining another projection, etc. A case of false-positive liver scan due to loculated ascites is presented in which these maneuvers failed to resolve the problem. Ultrasound or CT examination may be helpful in this circumstance due to the cross-sectional nature of the information they provide.

Acute gangrenous cholecystitis due to metastatic melanoma detected by cholescintigraphy.

A case of acute gangrenous cholecystitis due to cystic duct obstruction by a metastasis from malignant melanoma detected by cholescintigraphy is presented.

Ventilation-perfusion scintigraphy in an adult with congenital unilateral hyperlucent lung.

A variety of congenital and acquired etiologies can give rise to the radiographic finding of a unilateral hyperlucent lung. An unusual case of congenital lobar emphysema diagnosed in a young adult following the initial discovery of a hyperexpanded, hyperlucent lung is reported. Although subsequent bronchoscopy and radiologic studies detailed extensive anatomic abnormalities, functional imaging also played an important role in arriving at this rare diagnosis. In particular, ventilation-perfusion scintigraphy identified the small contralateral lung as the functional lung and helped narrow the differential diagnosis to etiologies involving obstructive airway disorders.

Rapid resolution of massive pulmonary embolism due to streptokinase therapy: documented by ventilation/perfusion imaging.

A case of massive pulmonary embolism is presented, with dramatic complete resolution within 36 hours due to anticoagulant and lytic therapy, documented by perfusion scintigraphy.

False-positive liver scan due to an intrahepatic gallbladder detected by cholescintigraphy.

A focal defect detected by hepatic scintigraphy is a nonspecific finding with a large differential diagnosis. This paper describes a case of an ectopic intrahepatic gallbladder diagnosed by cholescintigraphy, thereby avoiding a potential false-positive liver scan.