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Objectives: To evaluate the capability of sequential bone scintigraphy for assessing the viability of avascular onlay grafts in combination with primary or secondary implant placement., Methods: Forty-six patients with severe alveolar ridge atrophy received full-arch onlay grafts from the iliac crest. Twenty patients received primary insertion of endosseous implants, while secondary implant placement was performed in 26 patients after an average interval of 95 days. In cases of primary implant placement, bone scintigraphy was performed after grafting and before abutment connection. In patients with secondary insertion, bone scans were performed after grafting, before and after implant placement and before abutment connection. For bone scintigraphy, 8 MBq 99mTc-MDP/kg body weight were administered intravenously and anterior views of the skull were obtained 3 h later. Regions of interest were drawn over the grafted area and over the calvarium as a reference area. Ratios of count densities between jaw and calvarium were calculated as a measure of tracer uptake., Results: Bone grafts with primary insertion of implants showed a significant decrease (P = 0.0001) in ratios calculated for the whole graft from a mean of 3.53 after grafting to 2.35 before abutment connection. In cases of secondary implant placement, ratios decreased significantly after grafting from 4.04 to 2.78 before implant placement (P = 0.0001). After implant placement, there was a significant increase to 3.28 (P = 0.0062), which was followed again by a significant decrease to a mean ratio of 2.58 (P = 0.0437)., Conclusions: Sequential bone scintigrams can provide information about the viability of the graft at the time of implant insertion and may thus indicate the ability of the grafted bone to accomplish osseointegration.

This study investigates the incorporation of bone grafts used in maxillofacial surgery by means of [18F]fluoride ion and positron emission tomography (PET). It considers patients who received pedicle grafts for mandibular reconstruction or onlay grafts for alveolar ridge augmentation. Dynamic PET images and arterialized venous blood samples were obtained within a 1-h period after i.v. injection of [18F]fluoride. Assuming a three-compartment model and applying multilinear least squares fitting, bone blood flow (K1) and fluoride influx (Kmlf) were determined. Additionally Patlak plot analysis was used to calculate fluoride influx (Kpat). In cervical vertebral bodies as the reference region, mean values for flow of K1 = 0.1162 +/- 0.0396 ml/min/ml and influx of Kmlf = 0.0508 +/- 0.0193 and Kpat = 0.0385 +/- 0.0102 ml/min/ml were found. Essentially these figures are comparable with physiological values in animal and man reported in the literature. Early after surgery a significant increase in flow and influx compared to vertebral bodies was observed in the regions of osteosyntheses between grafts used for reconstruction and recipient bone (K1 = 0.2181, Kmlf = 0.1000 and Kpat = 0.0666 ml/min/ml) and in onlay grafts (K1 = 0.2842, Kmlf = 0.1637 and Kpat = 0.0827 ml/min/ml). At the same time pedicle grafts showed a significant increase in flow but not in influx (K1 = 0.2042, Kmlf = 0.0774 and Kpat = 0.0529 ml/min/ml). Furthermore Kpat was significantly lower in pedicle grafts than in onlay grafts. In follow-up studies a significant decrease in flow occurred in pedicle grafts and the regions of osteosyntheses. Moreover the latter showed a significant decrease in Kmlf as well. It is concluded that [18F(-)] PET depicted increased blood flow and osteoblastic activity in onlay grafts and regions of osteosyntheses, indicating bone repair in the graft and adjacent host bone early after surgery. For the regions of osteosyntheses the decrease in both parameters corresponded to uncomplicated healing. The lack of increased influx, although flow was increased in pedicle grafts, most likely indicates that some necrosis occurred in these grafts despite patency of anastomoses. It may be concluded that [18F(-)] PET provides further insight into the biology of graft incorporation.

Bone scintigraphy was applied in the follow-up of 24 patients who received bone grafts for reconstruction of the mandible after partial resection. Semiquantitative assessment of the grafts was done with a six-grade scoring system, based on comparison of tracer uptake in the graft and in the calvarium (as an internal control). Sixty-nine bone scans were evaluated. Late planar imaging was carried out in all cases, and single-photon emission tomography (SPET) was performed additionally in 34 of these cases. Complications were observed in four grafts. They occurred less frequently in revascularized grafts than in non-revascularized grafts. Planar scintigrams performed within 14 days after reconstruction showed a significantly higher tracer uptake in grafts with an uncomplicated further course than in those which developed complications. Follow-up scintigrams after 1 and 3 months revealed a significant increase in tracer uptake in grafts with an uncomplicated course. This was not apparent in grafts which developed complications. The tracer uptake was estimated to be higher on the basis of the SPET scans as compared with the planar scintigrams. It is concluded that bone scintigraphy is of prognostic value in the evaluation of bone grafts used for mandibular reconstruction. SPET seems to be more sensitive than planar imaging for the assessment of graft viability.

Nuclear medicine procedures have special indications in the follow-up of transplanted patients: In case of renal transplantation perfusion, function (glomerular filtration) and urinary flow measured by bolus application of 99mTc-DTPA is an important tool to detect and monitor acute tubular necrosis, rejection, urinary leakage, obstruction or vascular complications. This method is used for pancreatic grafts, too. To exclude rejection in case of heart transplantation more than one year after operation the antimyosin antibody scintigraphy is introduced avoiding biopsies. The radionuclide ventriculography is able to monitor heart function by determining the ejection fraction. Cholescintigraphy in liver transplants is sensitive to detect complications of bile flow. In case of an auxiliary liver transplantation a competition between two livers has been described. This method allows a distinction of functional performance of donor and recipient liver. The same problem is solved by ventilation-perfusion scan in lung transplants. Bone scintigraphy is of prognostic value for graft viability. Other radionuclide examinations have been developed to measure perfusion, glucose-, fat-metabolism to detect rejection episodes, abscesses or tumor recurrencies.