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Gallium uptake in myositis ossificans. Potential pitfalls in diagnosis.

Seven cases of gallium uptake in myositis ossificans are described. Gallium scans are done frequently in paraplegics, quadriplegics, and comatose patients to look for occult infection. It is important to be aware of possible gallium uptake in myositis ossificans, particularly in the extremities, which is frequent in these patients. Gallium uptake may be present prior to any abnormalities seen on plain films or CT scans. It is important to correlate roentgenograms with abnormal gallium scans, particularly in the extremities, to avoid potential pitfalls in diagnosis and prevent unnecessary antibiotic treatment. A bone scan should be obtained whenever possible, particularly when roentgenograms are negative, to confirm the diagnosis.

Adult↗

Gallium-67 citrate in cerebral infarction.

Cerebral scans were obtained on 30 "stroke" patients first with 99mTc pertechnetate and subsequently with 67Ga citrate. Of the 26 patients with abnormal 99mTc static scans, 17 (65%) showed the same abnormality in gallium citrate scans also. In 4 patients with positive technetium flow studies but negative static scans, no abnormality was seen in the scans obtained after gallium citrate injection. In none of the patients was the relative concentration of radioactivity in the lesion greater in the gallium image than in the technetium image. This study proves the nonspecificity of gallium citrate and thus its inability to differentiate cerebral tumor from cerebral infarction just on the basis of localization of gallium.

Aged↗

The role of gallium-67 scanning in febrile patients.

The source of sepsis in febrile patients can be a difficult diagnostic problem. Gallium-67 has been utilized as a diagnostic tool in the evaluation of these patients. A retrospective review was done of 47 patients who presented with pyrexia of unknown origin (27 patients), postoperative fever (11 patients), septicaemia (4 patients) and miscellaneous sepsis (5 patients). Whole body imaging with Gallium-67 gave an overall sensitivity and specificity of 86 and 77%, respectively, which compares favourably with previous studies. The sensitivity and specificity was similar in all patient subgroups. Gallium-67 allowed for more effective and directed use of organ-specific imaging modalities, such as computed tomography, ultrasound and guided intervention, in localizing and defining the source of sepsis. Where more than one possible source of fever was present. Gallium-67 scanning correctly identified the activity of the different foci. Gallium-67 scanning should be used early in the evaluation of patients presenting with fever of uncertain origin.

Fever of Unknown Origin↗

Role of lysosomes in gallium concentration by mammalian tissues.

Two microanalytical methods, electron probe X ray analysis (E P M A) and ion mass analysis (I A M) were used to study gallium incorporation in normal tissues (kidney, liver, mammary gland, bone marrow, bone tissue) and in experimental tumors. The very high sensitivity of I M A makes possible the detection of very low concentration of gallium (1 ppm) with a spatial resolution of 0.5 micron, on the other hand, E P M A of lower sensitivity (100 ppm) makes possible the relation between the gallium concentration and the ultrastructure of the cell. It was shown that gallium is concentrated in the lysosomes of both types of tissues, where it is precipitated in an insoluble form. In addition, gallium is systematically combined with phosphorus in these precipitates. These observations suggest an active intralysosomal concentrating mechanism related to the presence of local phosphatase activity.

Animals↗

Gallium scanning by conventional imaging and emission computed tomography in the pretreatment evaluation of lung cancer.

Gallium 67 citrate was evaluated with conventional scanning and emission computed tomography (CT) scanning as a method of pretreatment staging of the intrathoracic, especially mediastinal, spread of lung cancer. Of 31 patients with tumours of various histological types, the isotope was concentrated in the primary lesion in all but one. In 10 out of 12 patients who underwent surgical exploration conventional gallium scanning correctly indicated the mediastinum to be clear and identified two other patients with a tumour of the mediastinum not recognised by chest radiography or emission CT gallium scanning. Neither conventional nor emission CT gallium scanning produced false positive images. Conventional gallium scanning can give information about the mediastinum not available from chest radiographs or bronchoscopy.

Gallium Radioisotopes↗

Pulmonary Kaposi sarcoma in patients with AIDS: scintigraphic diagnosis with sequential thallium and gallium scanning.

Pulmonary Kaposi sarcoma associated with acquired immunodeficiency syndrome (AIDS) is difficult to diagnose because the clinical presentations and radiographic findings are nonspecific. The authors report three proved cases of AIDS-associated pulmonary Kaposi sarcoma diagnosed with sequential thallium and gallium scans. These scans demonstrated abnormal increase of pulmonary thallium uptake, whereas the gallium uptake was negative. In the authors' experience and in reports in the radiology literature, infected areas of the chest are generally thallium-negative on the delayed (3-hour) scans but are gallium-avid, whereas lymphomas are both thallium- and gallium-avid. The authors conclude that sequential thallium and gallium scans can be used to help diagnose pulmonary Kaposi sarcoma and distinguish it from other common AIDS-associated chest complications such as lymphoma and infections.

Acquired Immunodeficiency Syndrome↗

In vivo morphologic changes in the rat osteoclast induced by gallium nitrate: the result of toxicity or other effects?

Gallium nitrate, an approved antitumor drug, has found clinical application in the treatment of cancer-related hypercalcemia and of Paget's disease; the exact mechanism of its action, however, remains unknown. The present study utilized rats in a 7-day exposure to gallium at doses similar to those used clinically. Quantitative histomorphometry and ultrastructural examination of osteoclast fine structure were carried out on specimens from animals with documented hypocalcemia. Gallium exposure produced striking changes in the osteoclast. The number of nuclei/osteoclast increased, and the ruffled borders of the osteoclasts were markedly decreased along the length of the Howship's lacunar cavity. The absence of a decrease in osteoclast number and the types of changes seen in ultrastructure suggest that the mechanism of action of gallium seen here may differ from that of calcitonin, a nontoxic, reversible antiresorbing agent. Results underscore the difficulty in assessing the toxicity of agents such as gallium on the osteoclast, a mature differentiated cell which does not divide and which does not produce a characteristic extracellular matrix component.

Animals↗

Gallium-67 as a tumor-seeking agent in lymphomas--a review.

BACKGROUND: At present 67Ga can be considered one of the most widely used viability radiotracers. There is general consensus in the literature that 67Ga has the highest clinical value in the management of lymphoma patients. METHODS: We critically discuss the role of gallium scintigraphy in lymphoma patients on the basis of the experience of the Nuclear Medicine Division at the National Cancer Institute of Milan. RESULTS AND CONCLUSIONS: The sensitivity of gallium scan is very high (80-90%) in the staging and follow-up of Hodgkin's disease, and the method is also of great importance in the follow-up of lymphoma patients. We recommend scintigraphy to study the residual mediastinal mass after treatment. Our experiences during the follow-up of 189 lymphoma patients clearly showed the superior performance of gallium scan compared to MRI in the study of the mediastinal region after treatment. Sensitivity and specificity were both very high (90% and 96.9% vs 88.7% and 89.2%, respectively). Gallium scintigraphy can also be used to study the disease-free interval, post-treatment survival, early signs of recurrence and treatment response times. Comparison of the survival curves of 33 patients with diffuse large cell Non-Hodgkin's lymphoma examined at the National Cancer Institute showed a statistically significant difference (logrank test, P = 0.0125) between patients with positive and those with negative gallium scan after 4-6 cycles of chemotherapy.

Animals↗

Beguiled by the gallium. Thymic rebound in an adult after chemotherapy for Hodgkin's disease.

An 18-year-old woman was diagnosed as having Hodgkin's disease involving the mediastinal lymph nodes and lung parenchyma. A pretreatment gallium 67 scan showed increased uptake in the mediastinum. Chest radiograph and chest computed tomographic (CT) scans after chemotherapy demonstrated resolution of disease, and a repeated gallium scan was normal. Four months later, a surveillance gallium scan showed increased activity in the mediastinal and hilar regions with corresponding chest CT and magnetic resonance imaging (MRI) showing a retrosternal mass. Prior to committing the patient to aggressive treatment for presumed disease relapse, a biopsy of the mass was performed and a specimen showed normal thymus tissue. The patient has continued in remission without further therapy 3 years after her initial treatment, with subsequent normal gallium scans and a stable mass on CT and MRI. Thymic enlargement following chemotherapy can occur with Hodgkin's disease in young adults, and interpretation of imaging studies, including gallium scanning, must be made with this consideration in mind.

Adolescent↗

Critical evaluation of the gallium-67 scan for surgical patients with lung cancer.

Seventy-five patients with lung cancer underwent a gallium scan and thoracotomy with total mediastinal nodal dissection. Evaluation of mediastinal lymph nodes by means of the gallium scan showed a sensitivity of 23 percent (3/13), a specificity of 82 percent (31/38), an accuracy of 67 percent (34/51), a positive predictive valve of 30 percent (3/10), and a negative predictive value of 76 percent (31/41) in those patients whose primary tumors demonstrated uptake of radioactive gallium. The low sensitivity was due to an inability to detect microscopic disease in mediastinal lymph nodes. The specificity was decreased by gallium-67 uptake in enlarged inflamed nodes that contained no metastases. These results do not support the use of the gallium scan in the selection of patients with lung cancer for thoracotomy.

Adenocarcinoma↗

Gallium nitrate for the treatment of non-Hodgkin's lymphoma.

Mortality from non-Hodgkin's lymphoma (NHL) is high, thus defining the need for additional therapeutic agents for this disease. Gallium nitrate is a metal compound that is presently approved for the treatment of hypercalcaemia associated with malignancy. In clinical trials first conducted over two decades ago, this drug was found to have antineoplastic activity in NHL. However, its development as an antineoplastic agent for the treatment of NHL was never rigorously pursued. Gallium has unique mechanisms of action that include its binding to transferrin in the circulation and targeting transferrin receptors present on lymphoma cells. As it shares chemical properties with iron, gallium can disrupt critical steps in iron homeostasis that are essential for tumour cell viability and growth and can inhibit the iron-dependent activity of ribonucleotide reductase. The drug may also target other cellular processes unrelated to iron. Phase I/II studies have shown that gallium nitrate displays the most efficacy and lowest toxicity in NHL when administered as a continuous intravenous infusion, producing response rates of 43% in patients with relapsed or refractory NHL. It does not suppress the white blood cells or platelets and does not share cross-resistance with other chemotherapeutic drugs. These characteristics make it particularly attractive for the treatment of myelosuppressed patients and for incorporation into combination therapy. Multi-institutional Phase II clinical trials are in progress to evaluate gallium nitrate as a single agent or in combination. These studies will help define its role in the current treatment of NHL.

Animals↗

Gallium scanning in malignant fibrous histiocytoma.

Malignant fibrous histiocytoma (MFH) is a recently defined, well established clinical and pathologic entity. Five patients with MFH who had gallium-67 scans are described. An attempt is made to correlate the presence, absence, and extent of disease, as both primary and metastatic deposits showed avidity for gallium-67. After excision, patients with negative gallium scans were well, while metastatic disease was shown by gallium scans in two patients shortly before death. Gallium scanning is advocated for initial evaluation and follow-up of patients with MFH.

Abdominal Neoplasms↗

Cleansing the colon in gallium-67 scintigraphy: a prospective comparison of regimens.

Colonic accumulation of gallium-67 frequently complicates the interpretation of gallium-67 scintigrams. Although various modes of cleansing the colon prior to scintigraphy have been suggested, there is controversy over their efficacy and none have been tested prospectively. Three hundred nine patients undergoing gallium-67 scintigraphy were randomly assigned to one of four cleansing regimens: (1) a high fiber diet (78 patients); (2) castor oil (76); (3) milk of magnesia and cascara (76); and (4) not preparation (79). Patient compliance rates for the four regimens were 17%, 32%, 36%, and 46%, respectively. After noncompliant patients were excluded, gallium-67 scintigrams were graded for colonic activity on a scale of 0-3 by three independent, experienced observers. Gallium-67 activity in the colon was significantly less after administration of castor oil than after no preparation (p = 0.047). A high fiber diet also resulted in a substantial reduction of colonic activity when compared with no preparation; the difference, however, was not statistically significant (p = 0.083). Regimen 3 did not produce significantly better results than regimen 4 (p = 0.42). A major impediment to the success of any cleansing regimen seems to be poor compliance of patients.

Castor Oil↗

Postoperative recurrence of lung cancer: detection by whole-body gallium scintigraphy.

The records were reviewed of 111 consecutive patients who had lung cancer resected and who were followed with serial postoperative whole-body gallium scans. Scans were obtained preoperatively at intervals of 3-6 months for about 1 year after surgery and subsequently at yearly intervals. The period of follow-up varied from 1 1/2 to 8 years. Of 55 patients who developed tumor recurrence, a gallium scan was the first indicator of recurrence in 11 (20%) and was judged helpful in confirming or localizing a recurrence in another 14 patients (25%). False-positive rates were determined from 175 postoperative scans in the other 56 patients who did not suffer recurrence. Of these 175 scans, 15 (9%) demonstrated abnormalities that were sufficiently suspicious that an additional diagnostic procedure, other than chest radiography, was performed for clarification. However, in no case did the gallium scan result adversely affect the management of the patient. Our data demonstrate that routine postoperative whole-body gallium scanning can facilitate early detection of recurrence in some cases. Judicious use of gallium scanning in cases with clinically suspected recurrence can enable prompt localization, diagnosis, and treatment of recurrent tumor.

Bone Neoplasms↗

Planning mantle radiation therapy in patients with Hodgkin disease: role of gallium-67 scintigraphy.

Detection of all sites of lymphoma is imperative for accurate planning of radiation therapy. In patients with Hodgkin disease, mantle radiation is used to treat the thoracic lymph nodes; in those with early-stage or nonbulky disease, mantle and paraaortic radiation may be the only treatment given. CT scanning of the chest adds important information to that obtained from chest radiographs. Gallium-67 scintigraphy has also been used to provide additional information on sites of active tumor. To determine the usefulness of 67Ga-citrate scintigraphy in planning the portals for radiation therapy, we analyzed the radiation treatment plans in 26 consecutive patients with Hodgkin disease; in all 26 patients, the disease had been staged by chest radiographs, chest CT scans, and gallium-67 images. Gallium-67 imaging alone provided unique information that affected the treatment plans in three patients (12%). The combined results of gallium-67 imaging and CT scans influenced the planning of radiation therapy in eight patients (31%). Gallium-67 imaging was found to be an important adjunctive study for optimal planning of radiation therapy in patients with Hodgkin disease.

Gallium Radioisotopes↗

Inhibition of carious lesions in vitro around gallium alloy restorations by fluoride releasing resin-ionomer cement.

A new fluoride releasing resin-ionomer cement was used for bonding of gallium alloy restorations in vitro. Etching, priming, and fluoride releasing resin-ionomer cement were used in the experimental group (ARG), prior to placement of the gallium alloy restorations. Three different controls were used: gallium alloy only (G), no etching, fluoride releasing resin-ionomer cement, gallium alloy (RG), etching, priming, non-fluoride cement and gallium alloy (ACG). The mean shear bond strengths of ARG group to enamel and dentin were higher than those of the three control groups. Artificial secondary caries lesions around the restorations in the experimental group and the control groups were produced, using a strep. mutans culture. The microradiographs were examined for presence of a caries inhibition zone near the restoration. Caries inhibition zones were clearly detected around RG and ARG, but not around G and ACG. The results indicate that the fluoride releasing resin-ionomer cement provided good adhesion and caries inhibition in enamel and dentin.

Adhesiveness↗

[Utility of SPECT in gallium scintigraphy].

Whole-body gallium planar scintigraphy is a mainstay for the detection of tumors and inflammatory lesions. Recently, gallium SPECT (single photon emission computed tomography) has become more common in the clinical setting. This diagnostic modality is widely employed in our hospital, and lesions are actually detected by SPECT in some cases. Although the contrast of SPECT images is better than that of planar images, spatial resolution is limited by the limited matrix size. Thus, the overall diagnostic utility of SPECT remains to be confirmed. The usefulness of SPECT for the detection of gallium-accumulated lesions was evaluated in a phantom. In this study, we showed that SPECT is able to detect more smaller and lower gallium accumulations than planar imaging. Thus, SPECT imaging is useful in gallium scintigraphy.

Gallium Radioisotopes↗

Somatostatin receptor scintigraphy and gallium scintigraphy in patients with sarcoidosis.

UNLABELLED: Somatostatin receptor scintigraphy (SRS) has been shown to reveal sarcoidosis sites. The aim of this study was to prospectively compare SRS and gallium scintigraphy in the evaluation of pulmonary and extrapulmonary involvement in patients with proven sarcoidosis. METHODS: Eighteen patients with biopsy-proven sarcoidosis were included. Nine were or recently had been receiving steroid therapy at the time of the examination. Planar gallium scintigraphy (head, chest, abdomen, and pelvis) and thoracic SPECT were performed at 48-72 h after injection of a mean dose of 138 +/- 21 MBq 67Ga. Planar SRS and thoracic SPECT were performed at 4 and 24 h after injection of a mean dose of 148 +/- 17 MBq 111n-pentetreotide. RESULTS: Gallium scintigraphy found abnormalities in 16 of 18 patients (89%) and detected 64 of 99 clinically involved sites (65%). SRS found abnormalities in 18 of 18 patients and detected 82 of 99 clinically involved sites (83%). Of the 9 treated patients, gallium scintigraphy found abnormalities in 7 (78%), detecting 23 of 39 clinically involved sites (59%), whereas SRS found abnormalities in 9, detecting 32 of 39 clinically involved sites (82%). CONCLUSION: This study suggests that, compared with gallium scintigraphy, SRS appears to be accurate and contributes to a better evaluation of organ involvement in sarcoidosis patients, especially those treated with corticosteroids.

Adrenal Cortex Hormones↗