Benedict Cassen: the father of body organ imaging.

The invention of the radioisotope scanner by Benedict Cassen was seminal to the development of body organ imaging. Cassen assembled the first automated scanning system in 1950. It was a motor-driven scintillation detector coupled to a printer. The scanner was used to image the thyroid gland after the administration of radioiodine. Later, with the development of organ-specific radiopharmaceuticals the scanner was widely used during the late 50s until the early 70s to image the body organs.

Dynamic [18F]fluorodeoxyglucose positron emission tomography and hypometabolic zones in seizures: reduced capillary influx.

We performed dynamic [18F]fluorodeoxyglucose ([18F]FDG) positron emission tomographic (PET) analyses in 8 patients. Rate constants of influx (K1*), efflux (k2*), phosphorylation (k3*), and dephosphorylation (k4*) were derived for the regions of interest (ROIs), which included (1) the hypometabolic epileptogenic regions and (2) the homologous regions in the contralateral hemispheres. In addition, the four constants were determined from at least one clearly defined (control) ROI from the same plane and its homologous contralateral ROI. Influx (K1*) in the epileptogenic region was reduced in comparison with the contralateral ROI. Reductions in influx (K1*), which averaged 18 +/- 13% (mean +/- SD), [18F]FDG phosphorylation (k3*) (25 +/- 20%), and brain glucose utilization rates (26 +/- 10%) were observed in the epileptogenic region. Reductions in efflux were not statistically significant (k2* = 13 +/- 28%) but were comparable in magnitude to the average reduction in K1*. No ipsilateral versus contralateral differences were seen for any rate constants measured outside the epileptogenic region. Influx correlated highly with phosphorylation in the epileptogenic region. Our data suggest that the hypometabolic epileptogenic focus seen in [18F]FDG-PET studies is also a region of reduced blood-brain barrier glucose transporter activity and that reductions in phosphorylation are proportional to reductions in [18]FDG influx.

Ben Cassen and the development of the rectilinear scanner.

The development of the rectilinear scanner by Benedict Cassen was preceded by his successful fabrication of a directional scintillation detector probe. In 1950, Cassen assembled the first automated scanning system that was comprised of a motor driven scintillation detector coupled to a relay printer. The scanner was used to image thyroid glands after the administration of radioiodine. Initial studies that were performed at the West Los Angeles Veterans Administration Medical Center led to the extensive use of the scanning system for thyroid imaging during the early 1950s. Cassen's development of the rectilinear scanner was a defining event in the evolution of clinical nuclear medicine. In 1956, Kuhl and his colleagues developed a photographic attachment for the Cassen scanner that improved its sensitivity and resolution. With the development of organ-specific radiopharmaceuticals, a commercial model of this system was widely used during the late 1950s until the early 1970s to scan the major body organs. The decline of the rectilinear photoscanner began in 1973 with the advent of computed axial tomography.

Primary or working memory in frontal lobe epilepsy: An 18FDG-PET study of dysfunctional zones.

INTRODUCTION: We previously demonstrated that patients with frontal lobe epilepsy show deficits on a visual working memory paradigm and that this paradigm produces increased 18FDG uptake in the dorsolateral prefrontal cortex (DPFC), premotor cortex, angular and supramarginal gyri, basal forebrain, and ventral frontal poles of normal subjects when compared with a control task. We hypothesized that subjects with frontal lobe epilepsy would have impaired frontal activation during this task. METHODS: One resting and two activated images were obtained with 18FDG-PET in 15 subjects and 14 controls. One was a delayed (DMS) and one an immediate (IMS) match to sample paradigm. Discriminant and factor analyses were used to analyze the data, supplemented by selected t tests. RESULTS: No differences in glucose uptake were found between the DMS and IMS in the epilepsy subjects, in distinct contrast to controls. A comparison between controls and epilepsy subjects showed differences both ipsilateral and contralateral to the epileptic focus in the frontal regions involved in the task, with small changes in nonfrontal, task-related regions as well. The task itself brought out or highly exaggerated differences seen at rest. There was weak evidence that other frontal and temporal regions were attempting to compensate for the DPFC deficit. CONCLUSION: A unilateral epileptic focus is capable of suppressing function along a large task-related circuit ipsilateral and contralateral to the focus. Peripheral cortical regions compensate poorly for the area of dysfunction.

PET scans of abdominal malignancy.

Positron emission tomography (PET) with fluorine-18-2-d-deoxyglucose (FDG) currently is being integrated into clinical oncology because it provides unique functional information that can be applied to the management of cancer. In particular, it is useful for assessing tumor activity and growth, evaluating efficacy of therapy, and detecting tumor recurrence. Studies have demonstrated the value of whole-body PET-FDG imaging when staging and managing abdominal malignancy.

Age-associated memory loss: initial neuropsychological and cerebral metabolic findings of a longitudinal study.

To determine the relationships between clinical and brain function in persons with a familial risk for Alzheimer's disease, the authors assessed subjective and objective cognitive abilities, mood state, and cerebral glucose metabolism (using positron emission tomography) in 43 persons with age-associated memory impairment, with and without first-degree relatives with a clinical diagnosis of Alzheimer's disease. Subjective complaints of memory loss, mood state ratings, and objective memory measures were similar in persons with a family history of Alzheimer's disease (n = 29) compared to those without such a history (n = 14). Metabolic ratios in the frontal regions correlated with a decrease in a specific type of subjective memory complaint (mnemonics usage; p < .001) and some mood state ratings. These results indicate that parietal and temporal hypometabolism is not evident in persons with mild age-related memory complaints, even when such subjects have a familial risk for Alzheimer's disease. Moreover, self-reports of mnemonics usage may be sensitive indicators of decreased frontal lobe function. Longitudinal study will determine whether such clinical and metabolic measures will predict eventual disease progression.

Localized brain metabolic response correlated with potentials evoked by words.

Evoked potentials (EPs) measure synaptic current flows that propagate from brain to scalp, Alternatively, positron emission tomography (PET) using fluoro-deoxyglucose (FDG) can measure the increased glucose metabolism supporting this synaptic activation. It is difficult to localize the brain activity-generating EPs from their scalp distribution, because activity originating in different regions tends to produce overlapping scalp topographies. In contrast, FDG-PET provides better spatial resolution for activity throughout the brain, but shows only the total metabolism integrated over a 30-min uptake period. We combined the temporal and psychological resolution of EPs with the spatial resolution of PET to help define when and where in the brain words are encoded for meaning.

Malignant transformation of a Hürthle cell tumor: case report and survey of the literature.

Hürthle cell carcinoma is a relatively uncommon type of well-differentiated thyroid carcinoma. Its diagnosis has been controversial due to the difficulty in separating Hürthle cell adenoma from Hürthle cell carcinoma, thus the term Hürthle cell tumor is often used to describe both lesions. The present case of anaplastic giant-cell carcinoma in an 81-yr-old woman arose in a Hürthle cell tumor. This case illustrates the propensity of Hürthle cell tumor to undergo "malignant transformation" and argues for a more aggressive approach to such tumors.

Diagnosis of delayed cerebral radiation necrosis following proton beam therapy.

A 27-year-old man developed delayed cerebral radiation necrosis following proton beam therapy to an arteriovenous malformation. Neuroimaging with technetium 99m diethylenetriamine penta-acetic acid and positron emission tomographic scanning with fludeoxyglucose F 18 aided in his evaluation. Significant improvement of his neurologic deficits resulted from corticosteroid therapy. Clinical resolution was corroborated by serial computed tomographic scans demonstrating regression of the abnormality (a mass lesion). Various facets of radiation injury are discussed, including pathogenesis, risk factors, diagnosis, and therapy.

Neuroimaging in patients with seizures of probable frontal lobe origin.

Twenty-two patients whose electroclinical ictal characteristics suggested frontal lobe seizure foci were studied. Computed tomography (CT) scans showed abnormalities in only 32% of patients whereas magnetic resonance imaging was informative in 45%. 18FDG-Positron emission tomography (PET) scanning revealed decreased metabolism in 64% of the group. The areas of hypometabolism were focal, regional, or hemispheric. Focal frontal hypometabolism was significantly correlated with the electroclinical (semiologic) ictal localization. Therefore, FDG-PET scanning is a sensitive and specific technique for investigating patients with seizures of probable frontal lobe origins.

Effects of H1 blocking agents on age-related osteopenia in the mouse.

Old female B6AF1 mice were given acidified tap water, distilled water, one of five H1 blockers or chlorpheniramine (an H1 blocker) and trifluoperazine (a phenothiazine with no H1 blocking activity) in their drinking water for 5 months, and the effects of these agents on bone mineral metabolism were assessed by determining ash weights of femur, ilium and sacrum at the end of the study. In one experiment 24 h whole-body retention (WBR) of Tc 99m methylene diphosphonate (Tc 99m MDP, an indicator of bone metabolism) was measured at the beginning of the study and 40 days later. It was found that: promethazine and dimenhydrinate were the most effective of the H1 blockers in preventing age-related loss of bone mass; distilled water, chlorpheniramine, and chlorpheniramine plus trifluoperazine had no effect on the loss of bone mass; mean bone mass in the groups given meclizine and pyrilamine were greater than but not significantly different from that in the control group given acidified tap water; and only promethazine induced a significant reduction in the WBR of Tc 99m (the other H1 blockers induced small but not significant reductions).

Age-related osteopenia in the mouse: effects of an H1 blocker, a phenothiazine, and promethazine.

Mature and old B6AF1 and B6D2F1 mice were given acidified tap water or promethazine HCl (a phenothiazine with H1 receptor blocking activity), chlorpheniramine (an H1 blocker) or trifluoperazine (a phenothiazine with no H1 blocking activity) in their drinking water, and the effects of these agents on bone mineral content were assessed by intermittently measuring the 24-h whole body retention of Tc 99m methylene diphosphonate (Tc 99m MDP, an indicator of bone metabolism) and at the end of the studies by determining ash weights of femur, ilium and sacrum. It was found that 24-h retention of Tc 99m MDP was elevated in old mice as it is in old osteopenic humans, that promethazine but not chlorpheniramine or trifluoperazine inhibited bone loss in aging mice, and that there was a correlation between decrease in retention of Tc 99m MDP and decreased bone loss. These preliminary results suggest that the ability of promethazine to inhibit age-related bone loss may not be mediated through its action as an H1 blocker or as a phenothiazine. However, more agents of each type need to be tested before this point can be established.

Hair analysis for detection of phencyclidine in newly admitted psychiatric patients.

The authors implemented a new procedure for analyzing phencyclidine (PCP) content in hair. They compare the results of analyses of hair with results of analyses of blood and urine in 47 patients newly hospitalized with acute psychiatric illness. Hair analysis identified 11 patients who had used PCP, and blood and urine analyses did not identify any among the sample population. In three patients, the results of hair analysis aided in establishing a diagnosis of PCP intoxication. The authors discuss interpretations of their findings and psychiatric applications of this new technique.

Diagnosis of intraperitoneal extravasation of urine by peritoneal lavage.

The diagnosis of intraperitoneal extravasation of urine in the multiple trauma patient is often delayed, resulting in increased morbidity and mortality. To determine if intraperitoneal extravasation of urine can be detected by peritoneal lavage, an animal study was designed to investigate whether urea nitrogen and creatinine levels in the urine, serum, and lavage fluid would be predictive of urinary extravasation. Seventeen adult mongrel dogs, weighing 21 to 30 kg, were divided into two groups. The six dogs in Group 1 were utilized as controls, and had peritoneal lavage (15 mL normal saline/kg) performed using the open technique (direct visualization of the peritoneum). Blood, urine and lavage urea nitrogen and creatinine and lavage red cell count were measured. Group 2 (11 dogs) had varying amounts of urine (5 mL to 330 mL) instilled into the peritoneal cavity. Diagnostic peritoneal lavage was performed 30 to 45 minutes after the instillation of urine in all Group 2 animals. Group 2A (nine dogs) had urine instilled under direct visualization through a peritoneal lavage catheter. As bladder dome rupture is the most common cause of intraperitoneal urine extravasation, Group 2B (two dogs) had bladder dome ruptures performed by cystoscopic approach using the resectoscope. Cystograms were obtained in the bladder-ruptured dogs after completion of the peritoneal lavage to confirm intraperitoneal extravasation of bladder contents. In these animals, urine was instilled back into the bladder following bladder rupture. Results demonstrate that urea nitrogen and creatinine can be measured in peritoneal lavage fluid when extravasation of urine is in amounts of 15 mL or greater, and not measurable in amounts of 5 mL or less.(ABSTRACT TRUNCATED AT 250 WORDS)