A simple method for determining split renal function from dynamic (99m)Tc-MAG3 scintigraphic data.

PURPOSE: Commonly used methods for determining split renal function (SRF) from dynamic scintigraphic data require extrarenal background subtraction and additional correction for intrarenal vascular activity. The use of these additional regions of interest (ROIs) can produce inaccurate results and be challenging, e.g. if the heart is out of the camera field of view. The purpose of this study was to evaluate a new method for determining SRF called the blood pool compensation (BPC) technique, which is simple to implement, does not require extrarenal background correction and intrinsically corrects for intrarenal vascular activity. METHODS: In the BPC method SRF is derived from a parametric plot of the curves generated by one blood-pool and two renal ROIs. Data from 107 patients who underwent (99m)Tc-MAG3 scintigraphy were used to determine SRF values. Values calculated using the BPC method were compared to those obtained with the integral (IN) and Patlak-Rutland (PR) techniques using Bland-Altman plotting and Passing-Bablok regression. The interobserver variability of the BPC technique was also assessed for two observers. RESULTS: The SRF values obtained with the BPC method did not differ significantly from those obtained with the PR method and showed no consistent bias, while SRF values obtained with the IN method showed significant differences with some bias in comparison to those obtained with either the PR or BPC method. No significant interobserver variability was found between two observers calculating SRF using the BPC method. CONCLUSION: The BPC method requires only three ROIs to produce reliable estimates of SRF, was simple to implement, and in this study yielded statistically equivalent results to the PR method with appreciable interobserver agreement. As such, it adds a new reliable method for quality control of monitoring relative kidney function.

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.

Response of thyroglobulin to radioiodine therapy in thyroglobulin-elevated negative iodine scintigraphy (TENIS) syndrome.

BACKGROUND: While radioiodine (131-I) is widely used in the treatment of differentiated thyroid cancer, its role remains less certain when abnormal 131-I uptake cannot be demonstrated in a pre-therapy diagnostic scan. Documentation of abnormal 131-I uptake in a post-therapy scan in such cases helps to justify the radioiodine therapy, but the post-therapy scan can remain persistently negative. AIM: To evaluate (i) whether 131-I therapy had any measurable effect on thyroglobulin (Tg) levels in patients who were scan negative prior to radioiodine therapy and remained scan negative after therapy, and (ii) whether the magnitude of the effect on Tg depended on the pre-therapy Tg level. PATIENTS AND METHODS: Retrospective analysis of 78 patients. All patients had pre-therapy and post-therapy Tg levels measured under stimulation with thyroid stimulating hormone. Hospital data until date of last contact were analyzed to assess for recurrent disease. RESULTS: Tg levels decreased by 55% in those having Tg 10 µg/l or higher; and by 41% in those with less than 10 µg/l. In patients with detectable Tg antibodies, there were no statistically significant decreases demonstrated for either Tg or Tg antibody levels. CONCLUSION: Radioiodine therapy can reduce Tg levels, independently of the pre-therapy level, even when the pre-therapy level is low and the pre-therapy, as well as the post-therapy, radioiodine scan remains negative.

FDG PET/CT findings of a glomangiopericytoma.

Glomangiopericytoma (GPC) is a rare vascular neoplasm that arises almost exclusively from the nasal cavity or paranasal sinuses. GPC is also called sinonasal-type hemangiopericytoma, although current nomenclature, as well as classification in a group with myopericytomas, better emphasizes the relatively indolent behavior of this tumor. The authors present the FDG PET/CT findings of GPC in a 53-year-old with symptoms of nasal congestion and facial pressure. CT and MRI showed a nasal mass to extend along the sphenoid ridge from the posterior nasal cavity into the posterior nasopharynx. PET showed the mass to have uniformly low-grade FDG hypermetabolism. Pathologic examination of the surgical specimen showed classic features of GPC.

FDG PET of alveolar soft part sarcoma.

Alveolar soft part sarcoma (ASPS) is a very rare, but distinctive type of soft tissue sarcoma, whose name is derived from the pseudoalveolar appearance of its histology. In this report, the FDG PET/CT findings of ASPS are described in a 17-year-old asthmatic female who presented with worsening respiratory symptoms and a pelvic mass. The staging PET showed heterogeneous intense incorporation of FDG within the mass and variable FDG incorporation within the multiple lung nodules. In concordance with other soft tissue sarcomas, PET/CT helped to confirm the anatomic origin of the ASPS, to direct its biopsy, and to assess the distribution of disease.

Demonstration of thyroidal metastasis from lung cancer by F-18 FDG PET scan.

A case is presented of detection of a secondary thyroid cancer arising from a pulmonary adenocarcinoma by fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET). The need to investigate thyroidal hypermetabolic foci detected incidentally on PET scans is well established so as not to miss a primary thyroid cancer. However, as our case illustrates, the possibility of metastatic thyroid cancer, even though less common, should be considered.

Visualization of bullet track and bullet by radionuclide brain scintigraphy.

Radionuclide brain scintigraphy is a commonly performed examination for the confirmation of brain death. Although the absence of scintigraphically detectable flow of lipophilic tracers to the brain combined with the lack of uptake in the brain is considered consistent with brain death in the appropriate clinical scenario, the cause of death itself is usually not apparent on the scan. A case of bullet track and bullet visualization during a radionuclide brain death study with Tc-99m hexamethylpropyleneamine oxime (HMPAO) is described.

Scintigraphy as a confirmatory test of brain death.

The concept of "brain death" was introduced to medicine in the second half of the 20th century, when technological advancements began to allow sustaining cardiorespiratory functioning of the body in the absence of brain function. Although physicians generally agree that a patient can be declared brain dead when the loss of brain function is total and irreversible, different approaches have been taken to define what constitutes brain death. A thorough clinical examination is essential to the diagnosis. The role of confirmatory tests differ among countries in the world but generally are indicated when a specific part of the clinical examination cannot be performed or is deemed unreliable. Under certain circumstances, confirmatory tests can be used to shorten the clinical observation. Of the confirmatory tests recommended by the American Academy of Neurology and the American Academy of Pediatrics, cerebral scintigraphy is a safe, reliable, and widely available alternative. Once the radiopharmaceutical is properly compounded, cerebral scintigraphy can be performed rapidly and can be interpreted in a straightforward manner. It is tolerant of metabolic aberrations and pharmacologic intoxicants. It is not affected by electrical interference, and the presence of skull defects or scalp trauma do not preclude its performance. The radiopharmaceuticals used in scintigraphy have no deleterious effects on potential donor organs. Cerebral radionuclide angiography has been highly sensitive. Either cerebral planar scintigraphy or cerebral scintitomography with Tc-99m hexamethylpropyleneamineoxime also are highly sensitive, but, in addition, appear to be 100% specific.