technetium-tc-99m-medronate and Syncope

A "super scan" pattern detected on bone scintigraphy usually indicates either metabolic bone disease or diffuse metastases. We report a rare case of a 45-year-old man with recurrent episodes of syncope of 10 years' duration in whom bone scintigraphy showed a super scan with an axial skeleton distribution of uptake. Bone marrow biopsy established the diagnosis of systemic mastocytosis. The few reports in the literature of super scans associated with systemic mastocytosis showed diffuse axial and appendicular increased uptake. The present case shows a super scan involving the axial skeleton, which led to the diagnosis of systemic mastocytosis.

Topics: Bone and Bones; Humans; Male; Mastocytosis, Systemic; Middle Aged; Radionuclide Imaging; Radiopharmaceuticals; Recurrence; Syncope; Technetium Tc 99m Medronate

We evaluated regional electrical impedance (Z degree) at 2.5 and 100 kHz to separate intra- and extracellular fluid changes and correlated Z degree over the thorax (TI) to relative changes in the central blood volume (CBV) induced by head-up tilt. In nine experiments head-up tilt resulted in normotensive central hypovolaemia associated with a 3.7 +/- 0.4 Ohm (mean +/- SE) increase in TI100 kHz after 60 min. In 24 experiments pre-syncopal symptoms were induced after 43 +/- 2 min, when TI100 kHz had increased 4.2 +/- 0.2 Ohm. Head-up tilt instantly decreased the activity of technetium labelled erythrocytes (99Tcm) over the thorax by 24 +/- 2%, and increased 99Tcm over the thigh by 68 +/- 10% (P less than 0.01, n = 8) with no further changes during the sustained tilt. Haematocrite increased during head-up tilt from 43.1 +/- 0.3 to 47.9 +/- 0.6% (P less than 0.01, n = 8). Accordingly, the increase in TI (6.3 +/- 0.6 vs. 4.5 +/- 0.4 Ohm, n = 6) and the decrease in Z degree through one leg (7.2 +/- 1.2 vs. 2.8 +/- 0.5 Ohm, n = 6) at 2.5 kHz was more pronounced than at 100 kHz. Also the changes in TI were correlated to CBV as calculated from 99Tcm and haematocrite (r = 0.90, P less than 0.01). The results suggest that: (1) Hypovolaemic shock is associated with a faster increase of TI than normotensive head-up tilt. (2) Head-up tilt is characterized by an initial decrease in CBV followed by a further decrease in plasma volume, which eventually leads to hypovolaemic shock. (3) Blood volume changes during head-up tilt are reflected in regional Z degree.

Topics: Adult; Blood Volume; Body Fluids; Electricity; Erythrocyte Volume; Female; Head; Heart Rate; Hematocrit; Humans; Leg; Male; Prone Position; Syncope; Technetium Tc 99m Medronate; Thorax; Venous Pressure