Contrast material-enhanced MR imaging and PET allow quantification of volumetric and metabolic changes in joint inflammation and comparison of efficacies of antiinflammatory drugs.

FDG PET is a sensitive technique in the detection of MPNSTs in patients with NF1. The addition of 11C methionine PET increases specificity in equivocal cases. PET may improve preoperative tumor staging by detecting metastases or second primary tumors, which often are present in patients with NF1.

These results suggest that clinical heterogeneity in MCI is reflected in SPECT perfusion differences, and that the pattern of perfusion abnormalities evolves with increasing clinical severity.

Surgically unresectable primary and metastatic liver tumors have been increasingly treated with Y-90 radioembolization. In preparation for Y-90 radioembolization therapy, a baseline angiogram and a Tc-99m MAA hepatic perfusion study simulating Y-90 microsphere infusion are routinely performed, followed by a 2 nd angiogram in which the catheter is positioned in the same position as during the baseline angiography. However, radiotracer distribution on paired Tc-99m MAA hepatic perfusion imaging and post-therapy Y-90 bremsstrahlung imaging studies does not always match. The purpose of this study was to examine perfusion differences or mismatch which involve hepatic segment(s) and to identify underlying causes by correlating with angiography. 81 paired Tc-99m MAA hepatic perfusion imaging and post-therapy Y-90 bremsstrahlung imaging studies and corresponding angiograms were reviewed. 31 studies showed segmental perfusion differences (SPDs). SPDs were less frequently observed with infusion into the left hepatic artery (LHA) as compared to the proper (PHA) and right hepatic artery (RHA) (P<0.05). Significant associations were found with differences in catheter tip position between the two angiograms (P<0.001), catheter tip in proximity to an arterial bifurcation (P<0.01) or a small branch (P<0.01). Differences in catheter position, in combination with proximity to an arterial bifurcation or an arterial branch showed strong association with SPDs (P<0.001). In conclusion, when the catheter tip is in proximity to an arterial bifurcation or a branch, subtle differences in its position can alter microsphere perfusion or trajectory to the target vessels, which can be demonstrated by segmental perfusion mismatch on paired Tc-99m MAA hepatic perfusion imaging and posttherapy Y-90 bremsstrahlung imaging studies.

To evaluate the factors responsible for the accumulation of indium-111 immunoglobulin G (111In-IgG) at sites of inflammation, sequential measurements of tissue blood volume, interstitial fluid volume and accumulation of radiolabelled albumin and IgG were made in rats following Escherichia coli infection in the thigh. Compared with normal thigh muscle, there was approximately two-fold increase in interstitial fluid volume and approximately 1.5-fold increase in plasma and red blood cell volumes in infected muscle. For both proteins, there was a fivefold increase in influx rate constant (kin) in infected muscle. In normal muscle, the interstitial fluid concentration of labelled human serum albumin (111In-HSA) was significantly higher than that of 111In-IgG (P less than 0.01). In contrast, the concentrations in infected muscle were nearly identical. The concentration ratios (infected to normal muscle) were 1.7:1 for HSA and 3:1 for IgG. These data suggest that the infection imaging properties of 111In-IgG are related to expansion of the space available to macromolecules in infected tissue and increased transport into this space. At clinically important imaging times (24-48 h after injection), the higher target-to-background ratio of 111In-IgG compared with 111In-HSA is not due to the higher accumulation IgG in infected tissue but rather to the higher accumulation of HSA in normal tissue.