Scintigraphic confirmation of brain death

The concept of brain death has gained importance in the past few decades to prevent futile attempts to sustain ventilation and blood circulation when the brain has lost all function and to procure beneficial tissues or life-saving organs for transplantation. However, differences remain among professional societies and various study group recommendations, as well as among individual legal statutes, in how brain death is defined and the methodology for which the diagnosis is attained. Furthermore, reports have appeared both in the medical literature and the lay press concerning quality assurance measures in brain death documentation. Scintigraphy is a commonly used technique in the evaluation of brain death and can be performed with the use of either nonspecific tracers, such as Tc99m diethylene triamine pentaacetic acid, or brain-specific tracers, such as Tc99m hexamethylpropyleneamineoxime (HMPAO). Planar imaging, with or without radionuclide angiography, continues to be the mainstay for the scintigraphic confirmation of brain death. Flow with multiprojection static planar imaging with the use of Tc99m HMPAO can be used to evaluate the cerebral hemispheres, basal ganglia, thalamus, and cerebellum. Single-photon emission computed tomography (SPECT) can provide cross-sectional information but can be difficult to perform in the context of brain death. The current use of SPECT primarily is supplemental to help differentiate overlying scalp from intracerebral activity. The reliability of SPECT to exclude flow and metabolism in the brainstem remains to be scientifically validated.     

Scintigraphic visualization of extraosseous xanthomatosis

A histologically proven case of extraosseous xanthomatosis is presented. Both Ga-67 citrate and Tc-99m-MDP imagings demonstrated tumor uptake of radiotracers. A second Ga-67 imaging taken after excisional biopsy of the left knee lesion revealed disappearance of the lesional uptake of the tracer seen on the preoperative Ga-67 scan. Radiotracer accumulation in extraosseous xanthomatosis has not been reported previously.     

Frontal sinus outflow tract evaluation by sagittal computed tomography in frontal sinus fracture

The status of the frontal sinus outflow tract is important in the management of frontal sinus fractures. Anatomic and mucosal obstruction of the FSOT leads to mucociliary stasis with consequent infectious complications. This has been evaluated by routine CT scan.     

Scintigraphic visualization of inflammation in neurodegenerative disorders

In the past few decades, our understanding of the central nervous system has evolved from one of an immune-privileged site, to one where inflammation is pathognomonic for some of the most prevalent and tragic neurodegenerative diseases. Current research indicates that diseases as diverse as multiple sclerosis, stroke and Alzheimer's disease exhibit inflammatory processes that contribute to cellular dysfunction or loss. Inflammation, whether in the brain or periphery, is almost always a secondary response to a primary pathogen. In head trauma, for example, the blow to the head is the primary event. What typically concerns the neurologist and neurosurgeon more, however, is the secondary inflammatory response that will ensue and likely cause more neuron loss than the initial injury. This paper reviews the basic neuroinflammatory mechanisms, the potential neurotoxic mediators during activation of microglia, the brain resident macrophages, and their role in neurodegeneration. Alzheimer's disease is taken as a prototype for exploring these mechanisms, as it expresses more than 40 inflammatory mediators, it is the most extensively studied disorder in terms of immune-related pathogenesis, and because of its importance as the most prevalent type of dementia. Tools for the visualization of these neuroinflammatory processes, both structural and mainly functional, are critically reviewed and discussed.     

Scintigraphic evaluation of diabetic osteomyelitis: concise communication

We have reviewed the three-phase bone scans, radiographs, and histologic findings of 39 diabetic patients with serious foot problems. The sensitivity and specificity of bone scans were 83% and 75%, respectively, for osteomyelitis of the small bones of the foot. The positive and negative predictive values were 87% and 69%, respectively. The radiographs were less sensitive (62%) and less specific (69%), with predictive values of 80% (positive) and 47% (negative).     

Scintigraphic evaluation of pulmonary embolism

Pulmonary embolism (PE) is difficult to diagnose. The clinical signs and symptoms of the disorder are nonspecific, and the results of laboratory tests are undependable. Accordingly, imaging studies have played a major role in evaluation of patients with suspected PE. Chest radiography is an essential part of this imaging evaluation, but is neither sensitive nor specific, per se. The radiograph is used primarily to provide a regional comparison for ventilation-perfusion (V-P) scintigraphy. V-P scintigraphy typically is the pivotal noninvasive approach to diagnosis of PE. Multiview perfusion scintigraphy is a sensitive means for detecting the multiple, wedge-shaped defects characteristic of PE. The perfusion scan's inherent nonspecificity is improved by the ventilation study, which reveals abnormalities of ventilation that account for perfusion defects not caused by PE. Multi-view ventilation imaging with either the xenon gases, Kr-81m or radioaerosols is useful for comparison with perfusion scans. When performed properly and interpreted within the guidelines of current diagnostic schemes for scintigraphy, V-P studies provide approximately 90% reliability for the diagnosis of PE. When used alone or in conjunction with noninvasive studies of deep venous thrombosis, they provide an excellent basis for selection of certain patients for pulmonary angiography, and for other decisions about the clinical management of patients with suspected PE.

     

Scintigraphic evaluation of Zenker's diverticulum

Zenker's diverticulum (ZD) is a rare pathology, with a prevalence of between 0.01% and 0.11%. Definitive diagnosis of ZD can be accomplished by contrast radiographic examination (barium oesophagogram, BE); oesophageal manometry (ME) is recommended mainly for those patients suffering from dysphagia and/or gastro-oesophageal reflux. The aims of the present study were to assess whether oropharyngo-oesophageal scintigraphy (OPES) is able (a) to visualise ZD and (2) to demonstrate the corresponding alteration in the swallowing phases. We studied 16 patients (nine male, seven female, mean age 67.4 years), and 17 healthy volunteers (ten male, seven female, mean age 53 years) as a control group. All the patients underwent ME, BE and OPES. Nine patients underwent surgery and six of them were re-evaluated after 6 months. We administered 10 ml of water with 37 MBq of technetium-99m colloid through a straw, acquiring 480 sequential images (0.125 s/frame for a total of 60 s) with the patient standing in front of the gamma camera in the 80° right anterior oblique position. Two static images were performed at the end of the dynamic phase, before and after ingestion of 100 ml of unlabelled water to evaluate the presence of inflammation (persistence of radioactivity in the diverticulum or oesophagus). Study of the sequential scintigraphic images and time-activity curves permitted both qualitative (diverticulum visualisation, multiple deglutitions, reflux, presence of inflammation) and quantitative analyses [oral, pharyngeal and oesophageal transit times and retention indexes, tracheal aspiration percentage] of swallowing disorders. OPES showed a good correlation with the results of other diagnostic techniques usually performed in patients with this pathology, and especially with ME in the evaluation of oropharyngeal phase disorders. Furthermore, OPES is a sensitive and simple technique that is well tolerated and entails a low irradiation dose for patients.     

Scintigraphic evaluation of craniopagus twins

Craniopagus twinning is a rare congenital abnormality, occurring at a frequency of 4-6 per 10 million births. A case is reported in which separation was successful for both twins. The importance of pre-operative radionuclide assessment of crucial organ function (liver, kidneys, heart, brain) and crossed circulation is stressed. The scintigraphic results were in keeping with radiographic, operative, and clinical findings. The routine use of radionuclide studies in the investigation of conjoined twins is recommended in order to delineate individual organ function, degree of fusion and measurement of cross-circulation.     

Scintigraphic evaluation of aggressive fibromatosis

Despite its benign microscopic appearance, aggressive fibromatosis has potential to recur and infiltrate neighboring tissues. Therefore, it is necessary to determine the exact extent before therapy. In the present study, 11 cases of aggressive fibromatosis were examined scintigraphically using [99mTc(V)]dimercaptosuccinic acid (11 cases) and 67Ga-citrate (7 cases). Technetium-99m-(V)-dimercaptosuccinic acid demonstrated all lesions, while 67Ga-citrate detected 57% of the cases.     

Isolated inferior sagittal sinus thrombosis: a case report

We present a case of isolated inferior sagittal sinus thrombosis shown on CT, MRI and angiography. This condition has not, to our knowledge, been described previously. Received: 17 June 1996 Accepted: 13 August 1996     

Scintigraphic visualization of bacterial translocation in experimental strangulated intestinal obstruction

Purpose  

The purpose of this study was to obtain scintigraphic images depicting translocation of ^99mTc-labelled Escherichia coli bacteria through the intestinal barrier and to quantify this process using methods of nuclear medicine.     

Scintigraphic visualization of ocular melanoma with Tc-99m glutathione

In a patient with ocular melanoma scintigraphy obtained with^99mTc-GSH clearly demonstrated the histologically proven ocular lesion both in planar and SPECT images.^99mTc-sestamibi study obtained in the same patient three days later was negative.^99mTc-GSH is a potential alternative to the currently used radiopharmaceuticals for imaging both cutaneous and ocular melanomas and their metastases.     

Scintigraphic evaluation of cardiac autonomic innervation

Alterations in cardiac autonomic neuronal function have become the focus of intense research in various cardiovascular diseases. Both single-photon emission tomography (SPECT) and the positron emission tomography (PET) imaging techniques in combination with radiolabled neurotransmitters and receptor ligands have become available for the scintigraphic visualization of presynaptic and postsynaptic neuronal function. Several clinical studies have shown changes in tracer distribution in different clinical conditions, such as ischemic heart disease, congestive heart failure, malignant arrhythmias, heart transplantation, and in patients with diabetes. In patients with congestive heart failure, previous in vitro investigations have concentrated on the postsynaptic level of the sympathetic innervation. However, alterations in presynaptic nerve function have been demonstrated with scintigraphic investigations by decreased presynaptic tracer retention. Moreover, correlation between scintigraphic findings and clinical outcome was shown in patients with heart failure, providing important prognostic information superior to conventional risk assessment. In conclusion, scintigraphic evaluation by SPECT and PET allows functional characterization of cardiac presynaptic and postsynaptic neurons. Regional tracer uptake can be used as an index for the integrity of innervation in various diseases. Newer tracer approaches may allow the noninvasive quantification of neuronal function by PET.