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Biomedical subjects

D Front

Publications and source records attributed to D Front.

30 records · Page 2Linked to original sources

Bone scintigraphy in primary tumors of the head and neck.

Bones of the face and skull may be involved directly by adjacent primary tumors of the head and neck. Radiography, at present the standard method for detection of bone involvement in such tumors, is not sufficiently sensitive. Of 22 patients who showed bone involvement in scintigraphy, radiography in 15 was initially normal, in 6 the extent of the lesion was not completely shown and only in 3 was it as informative as scintigraphy. Bone scintigraphy should become a standard method for evaluation of the context of bone invasion by tumors of the head and neck.

Bone and Bones

The value of delayed (24-hour) bone scintigraphy.

Delayed 24-hour scintigraphy was performed in 23 patients. It was found to be useful in enhancing abnormal uptake, enabling better anatomic localization and verifying doubtful uptakes in the 4-hour study. The underlying causes of these observations are probably a better lesion-to-blood ratio and a slow uptake in certain lesions.

Bone Neoplasms

Doughnut phenomenon in bone scintigraphy.

A doughnut phenomenon was observed in bone scintigraphy in three cases of metastatic thyroid carcinoma to the skull. Additional dynamic and static studies were performed to evaluate the relative roles of vascularity, vessel permeability and new bone formation in producing this phenomenon. This was accomplished through the use of 99mTc-diphosphonate, 99mTc-labeled red blood cells and 99mTc-pertechnetate. The important factor was found to be a new bone formation. Late uptake of diphosphonate was shown only in the periphery of the lesion, where formation of new bone takes place. This occurred even in the presence of increased vascularity and vessel permeability in the lesion as a whole.

Adenocarcinoma

Perfusion vascularity mismatch in liver hemangiomas.

Perfusion defect in the dynamic study and slow filling of the lesion by a blood pool agent were observed in three cases with large cavernous hemangiomas of the liver. This finding is explained by the low perfusion and the large blood volume of cavernous hemangiomas. When such a lesion is suspected a late blood pool study should be performed in order to demonstrate the true vascularity of the lesion.

Angiography

Scintigraphic assessment of vascularity and blood-tissue barrier of human brain tumours.

Assessment of vascularity and blood-tissue barrier was performed by sequential scintigraphy in 43 patients with brain tumours. The blood-tumour barrier was evaluated by use of 99mTc-pertechnetate, and vascularity using 99mTc-labelled red blood cells. Three groups of tumours were found: tumours with low vascularity and permeable barrier, tumours with high vascularity and permeable barrier, and tumours with low vascularity and relatively impermeable barrier. The first group indicates that when vessels are permeable, there may be a rapid penetration of large amounts of pertechnetate into the tumour even when vascularity is not increased. In the other two groups penetration of pertechnetate into the tumour is affected by vascularity, as it determines the total area where passage of the radiopharmaceutical takes place. It is suggested that the permeability of the blood-tumour barrier and the amount of vascularity may have an effect on the success of chemotherapy in brain tumours.

Blood-Brain Barrier

Chronic familial hyperphosphatasemia.

Two siblings displaying macrocrania and multiple skeletal deformities, as well as cardiomegaly, had high levels of serum alkaline phosphatase and markedly increased urinary hydroxyproline excretion. The radiological findings of chronic familial hyperphosphatasemia, which are typical of a rare bone-remodeling disease, are presented. Scintigraphy disclosed intense uptake of the radionuclide by the skeletons of both patients. This finding, considered to be related to abnormal collagen metabolism, can be used in the diagnosis and assessment of skeletal involvement in such patients.

Bone and Bones

Bone scintigraphy in scurvy.

Scintigraphic bone changes in two cases of scurvy are described, the cause being subperiosteal hematoma. Generalized increased uptake was shown in the affected femur at an early state of the disease. At a late stage, marked uptake both in the femoral shaft and surrounding tissue was seen causing scintigraphic appearance of widened ("club-shaped") femur.

Child, Preschool

Convexity leptomeningeal cysts diagnosed by scinticisternography.

The scintigraphic diagnosis of eight convexity leptomeningeal cysts is described; the cysts appear as a local collection of abnormal radioactivity, best seen at 48 hours. The correlation of the scintigraphic findings with clinical, radiological, and operative findings is discussed.

Adolescent

Contribution of nuclear medicine to the diagnosis and management of extracranial head and neck diseases (excluding thyroid and parathyroid).

Nuclear medicine contributes to the diagnosis and management of extracranial head and neck diseases through the physiological information it provides. In addition to thyroid and parathyroid indications, radionuclide studies, i.e., bone and 67Gallium citrate scans are helpful in diagnosing and treating head and neck malignancies. Positron emission tomography with 18F-fluorodeoxy-glucose evaluates tumor glucose metabolism before and after treatment. Triphase bone scintigraphy enables early detection of osteomyelitis of the skull base, and its management requires 67Gallium-citrate or 111Indium-WBC scintigraphies. Salivary gland scintigraphy is the only functional imaging test of salivary tissue and should be utilized more in the diagnosis of submandibular duct obstruction and in the evaluation of preserved parenchymal function after recurrent infections.

Adolescent