Lymphoscintigraphy is increasingly used to identify the first draining node (sentinel node) in patients with malignant melanoma or breast cancer. If the sentinel node is tumor free then the remainder of the nodes in that specific nodal bed are likely to be free of metastases. Localization and biopsy of the sentinel node with an intraoperative surgical probe may obviate more radical lymph node dissection. Lymphoscintigraphy is conventionally performed by injecting the radioactive tracer in the four quadrants around the primary tumor and imaging the appropriate nodal beds approximately 30 minutes later. The visualized node nearest the tumor usually is assumed to represent the sentinel node. To test this assumption, a dynamic acquisition was obtained in 16 patients with malignant melanoma to determine if the node nearest the tumor was actually the first draining node. In one of 16 patients, the radioactive tracer injected around a thigh melanoma drained first to an inguinal node and then drained inferiorly to a second inguinal node located closer to the tumor. The distinction between the sentinel and satellite (secondary draining nodes) may have important clinical implications regarding the number of nodes that require surgical excision. In summary, static images do not define the pattern of lymph flow and the node nearest the tumor is not necessarily the sentinel node. Failure to obtain dynamic images may lead to misdiagnosis of the sentinel node in a small percentage of patients.

Humans↗

PubMed1995

Lymphoscintigraphy and the intraoperative gamma probe.

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Antimony↗

PubMed1994

The brain in older persons with and without dementia: findings on MR, PET, and SPECT images.

Neuroimaging plays an increasingly important role in the evaluation of dementias of older adults. Although no unequivocal diagnostic test other than biopsy is currently available for Alzheimer's disease and some other dementias during life, neuroimaging techniques are an integral part of the examination and follow-up of patients with dementia. This review describes findings in the brains of patients with normal aging and in elderly patients with dementia, as shown by MR imaging and MR spectroscopy, positron emission tomography (PET), and single-photon emission computed tomography (SPECT) and correlated with clinical and pathologic features.

Aged↗

PubMed1993

Clinical practice versus research: how can radiology win?

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Radiology↗

PubMed1993

Value of technetium 99m sestamibi iodine 123 imaging in reoperative parathyroid surgery.

BACKGROUND: The purpose of this study was to assess the contribution of technetium 99m sestamibi iodine 123 (T/S) imaging to preoperative and intraoperative management of patients with persistent hyperparathyroidism. METHODS: During a period of 10 months, all patients being prepared for reoperative parathyroid surgery (n = 10), two patients deemed significant operative risks (one patient with severe chronic obstructive pulmonary disease and one patient with severe cervical spine ankylosing spondylitis), and two patients who had undergone prior thyroid operation were studied with T/S imaging. Six patients undergoing reoperative surgery had undergone one, three had undergone two, and one had undergone three prior procedures. RESULTS: T/S imaging correctly localized 14 of 16 parathyroid tumors. By comparison, only 1 of 6 thallium technetium and 3 of 12 computed tomography (CT) scans (in seven patients) were positive. T/S imaging guided the reoperative surgical approach accurately in 12 of 14 patients, including one case of an undescended left lower gland at the level of the mandible and identification of a third gland on the left in another case. Sternal split was required to remove three lesions localized by T/S imaging, two beneath the aortic arch and one nestled in the aortopulmonary window in a patient who had undergone two prior procedures including a sternal split. In these three cases T/S imaging was particularly useful, because CT scans, thallium technetium scans, magnetic resonance imaging, and arteriography were not diagnostic. The outcome after operation was favorable in all 14 cases, with correction of hypercalcemia and no permanent laryngeal nerve injuries or hypocalcemia. CONCLUSIONS: We concluded that T/S imaging is more accurate than thallium technetium and CT scans in evaluation of patients with persistent hyperparathyroidism.

Adult↗

PubMed1990

Technical aspects of myocardial SPECT imaging with technetium-99m sestamibi.

Most reports to date using single photon emission computed tomography (SPECT) with technetium-99m (Tc-99m) sestamibi have used acquisition parameters that were optimized for thallium-201. To fully utilize the superior imaging characteristics of Tc-99m sestamibi, there is a need to optimize the technical aspects of SPECT imaging for this agent. Performance can be enhanced through the careful selection of optimal radiopharmaceutical doses, imaging sequences, acquisition parameters, reconstruction filters, perfusion quantification methods and multidimensional methods for visualizing perfusion distribution. The current report describes theoretical considerations, phantom studies and preliminary patient results that have led to optimized protocols, developed at Emory University and Cedars-Sinai Medical Center, for same-day rest-stress studies, given existing instrumentation and recommended dose limits. The optimizations were designed to fit a low-dose-high-dose rest-stress same-day imaging protocol. A principal change in the acquisition parameters compared with previous Tc-99m sestamibi protocols is the use of a high-resolution collimator. The approach is being developed in both prone and supine positions. A new method for extracting a 3-dimensional myocardial count distribution has been developed that uses spherical coordinates to sample the apical region and cylindrical coordinates to sample the rest of the myocardium. New methods for visualizing the myocardial distribution in multiple dimensions are also described, with improved 2-dimensional, as well as 3- and 4-dimensional (3 dimensions plus time) displays. In the improved 2-dimensional display, distance-weighted and volume-weighted polar maps are used that appear to significantly improve the representation of defect location and defect extent, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer Graphics↗

PubMed1990

Myocardial perfusion imaging with technetium-99m sestamibi SPECT in the evaluation of coronary artery disease.

Technetium-99m (Tc-99m) sestamibi is a new myocardial perfusion imaging agent that offers significant advantages over thallium-201 (Tl-201) for myocardial perfusion imaging. The results of the current clinical trials using acquisition and processing parameters similar to those for Tl-201 and a separate (2-day) injection protocol suggest that Tc-99m sestamibi and Tl-201 single photon emission computed tomography (SPECT) provide similar information with respect to detection of myocardial perfusion defects, assessment of the pattern of defect reversibility, overall detection of coronary artery disease (CAD) and detection of disease in individual coronary arteries. Tc-99m sestamibi SPECT appears to be superior to Tc-99m sestamibi planar imaging because the former provides a higher defect contrast and is more accurate for detection of disease in individual coronary arteries. Research is currently under way addressing optimization of acquisition and processing of Tc-99m sestamibi studies and development of quantitative algorithms for detection and localization of CAD and sizing of transmural and nontransmural myocardial perfusion defects. It is expected that with the implementation of the final results of these new developments, further significant improvement in image quality will be attained, which in turn will further increase the confidence in image interpretation. Development of algorithms for analysis of end-diastolic myocardial images may allow better evaluation of small and nontransmural myocardial defects. Furthermore, gated studies may provide valuable information with respect to regional myocardial wall motion and wall thickening. With the implementation of algorithms for attenuation and scatter correction, the overall specificity of Tc-99m sestamibi SPECT should improve significantly because of a substantial decrease in the occurrence of attenuation-related image artifacts.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗

PubMed1990

Bone scans after total knee arthroplasty in asymptomatic patients. Cemented versus cementless.

The natural history of bone scans after total knee arthroplasty (TKA) was studied in 26 patients with 28 cemented TKAs and 29 patients with 31 cementless TKAs. The bone scans were examined at specified postoperative intervals. Radionuclide activity of the femoral, tibial, and patellar regions was measured. Six patients who developed pain postoperatively were excluded. Bone scans immediately postoperative and at three months demonstrated increased uptake, which gradually decreased to baseline levels at ten to 12 months. Radioisotope uptake was comparable in the cemented and cementless groups, but was highly variable in individual patients and in each of the follow-up periods. A single postoperative bone scan cannot differentiate component loosening from early bone remodeling. Sequential bone scans, as a supplement to the clinical examination and conventional radiography, may prove useful in the diagnosis of TKA failure.

Aged↗