The results of this study indicate that a 99mTc sestamibi scan is a valuable imaging method for the determination of digital ischaemia in vasospastic Raynaud's syndrome, and may play a role in evaluating the response to therapy.
An experimental study was designed to assess the viability and revascularization of intramuscularly injected fat autografts. For the study, 18 rabbits were divided into two groups. In the first group, fat was injected intramuscularly (12 rabbits). Autologous fat was obtained from the inguinal area and subsequently injected into the thigh muscle. In the second group, physiologic saline was injected intramuscularly to determine the effects of cannulation and pressure on muscle tissue (6 rabbits). Fat autografts were performed on the right side of the animal, and the left side was used as the control. Scintigraphic imaging and histopathologic examination of the limbs were performed after injection of adipose tissue on days 15, 30, 45, 60, 90, and 120. On the technetium-99m ((99m)Tc) hexamethylpropylene amine oxime scintigraphy, whereas similar activity distribution was observed between the left and right thigh on days 15, 30, and 45, there was increased uptake at the right thigh on days 60, 90, and 120. This increased uptake indicates that there is viable fat tissue in this region. Histopathologic evaluation showed that microcysts resulting from degeneration of some adipocytes and inflammatory changes on day 15 additionally increased vascularity and fibrosis in some animals on day 30, as well as fibrosis, microcysties, and focal calcification areas in adipose tissue on day 45 and later. It was observed that adipose tissue survived in more than 50% of the graft area in all the animals. These findings show that fat autografts can survive in muscle tissue with less than 50% fibrotic change.
The results of our study show that the optimal imaging times after intravenous injection of MIBI are 15 minutes and 1 hour because of the shorter examination time without loss of diagnostic ability. In the present study, there was no significant correlation between MIBI uptake ratios and increased gland volume, or serum Ca and i-PTH levels. Besides, we think that oxyphil cell content may not have a main effect on MIBI uptake and retention. The fact of an adverse relation between phosphorus and MIBI retention in our study suggests that phosphorus level should be considered prior to MIBI imaging.
Reflex sympathetic dystrophy (RSD) has widely variable clinical manifestations. Its pathogenesis remains partially unexplained. RSD is commonly divided into three stages; these stages are not always clearly separable, but staging remains important for correct treatment. Since the disease involves soft tissue alterations as well as bone changes, we decided to investigate whether technetium-99m sestamibi limb imaging can be used to evaluate the soft tissue appearance. Fifteen patients (seven females and eight males; age range 12-68 years) with clinically significant post-fracture RSD were evaluated with both three-phase bone scan (TPBS) and 99mTc-sestamibi limb scintigraphy. Although, in general, patients with similar duration of disease, clinical stage and TPBS activity tended to have similar patterns of sestamibi uptake, discordant uptake patterns were observed in some patients with clinical stage 1. Thus, of 12 patients with stage I disease, eight had increased 99mTc-sestamibi activity in the distal part of the affected limb, while three had normal activity and one had decreased activity. All three patients with stage II disease showed normal 99mTc-sestamibi uptake. Although most of the patients with increased 99mTc-sestamibi uptake had increased activity on all three phases of the bone scan, there were discordant results between the scan patterns in other patients. On the basis of these findings, we suggest that 99mTc-sestamibi imaging may contribute to the differentiation between clinical stages and may permit evaluation of the disease course and selection of appropriate therapy. 99mTc-sestamibi imaging is not, however, a primary diagnostic procedure for RSD.
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