In vivo uptake of technetium-99M-sestamibi by parathyroid glands in comparison to surrounding tissues of the neck.

Technetium-99M-sestamibi (Tc-99M-sestamibi) has recently been proven to be a sensitive and specific agent for imaging of parathyroid disease; however, the selective nature of its uptake by different tissues has not been investigated. Fifteen consecutive patients undergoing neck exploration for hyperparathyroidism were given 3 to 15 mCi of Tc-99M-sestamibi at various times before surgery, and at the time of exploration, samples of parathyroid tissue, blood, fat, muscle, and thyroid were taken from the neck. All samples were carefully weighed and counts of radioactivity were measured. Activity was normalized to counts per gram of tissue and counts of radioactivity were compared using a multiple range analysis of variance test. Mean counts per gram (+/- SE) in abnormal parathyroid tissue (adenomas and hyperplastic glands; 1.1 x 10(6) +/- 2.7 x 10(6)) were significantly higher than in any of the other tissues measured (P < 0.05): thyroid, 7.0 x 10(4) +/- 1.6 x 10(4); muscle, 8.9 x 10(4) +/- 2.1 x 10(4); fat, 2.1 x 10(4) +/- 4.2 x 10(3); and blood, 9.8 x 10(3) +/- 2.3 x 10(3). Mean ratios of counts (+/- SE) of abnormal parathyroid tissue to other tissues were found to be as follows: thyroid, 35.3 +/- 12.6; muscle, 17.4 +/- 6.2; fat, 80.7 +/- 20.0; and blood, 161.0 +/- 31.6. From these data, Tc-99M-sestamibi clearly exhibits significantly higher uptake in abnormal parathyroid tissue relative to other tissues measured in the neck. This increased uptake in parathyroid gland tissue accounts for the utility of Tc-99M-sestamibi in localization studies for hyperparathyroidism. Quantification of in vivo uptake of Tc-99M-sestamibi may help refine techniques for improved localization of hyperfunctional parathyroid glands.

The influence of early surface thromboreactivity on long-term arterial graft patency.

The influence of early graft surface thromboreactivity on long-term arterial polyester (Dacron) graft patency was investigated with separate ex vivo and in vivo animal models. First, parallel, flow-regulated external aortocaval fistulae were created in five pigs with use of paired 8 mm X 35 cm crimped, warp-knitted, low-profile filamentous velour Dacron tubes: one tube preclotted with autologous blood, the other autoclaved after being soaked in human albumin. Autologous radiolabeled platelets, red cells, and radiolabeled human fibrinogen were injected at initiation of graft flow, with timed graft samples submitted for isotope gamma well-counting. Flow surface accumulation of radiolabeled blood elements was greater on the preclotted graft limb at-all time intervals studied, greatest after 5 minutes of flow initiation with RBC accumulation on the preclotted limb 5.19 +/- 0.84 (x +/- S.E.), platelet accumulation 5.57 +/- 1.00, and fibrinogen accumulation 1.82 +/- 0.14 times greater than that on the albumin-treated limb. Second, bilateral iliofemoral artery bypass grafts were placed in 12 mongrel dogs using 6 mm X 10 cm externally supported, noncrimped, warp-knitted, low-profile filamentous Dacron tubes. Before implant in each dog, one graft limb was clotted with autologous blood and the other was autoclaved after being soaked in 25% human albumin. Fresh autologous radiolabeled platelets were injected after wound closure in seven of these dogs. Postimplant graft imaging at 24 and 72 hours showed radiolabeled platelet accumulation to be 1.43 +/- 0.21 and 2.05 +/- 0.18 times greater on the preclotted graft limb. Six of 12 preclotted graft limbs and 7 of 12 albumin-treated graft limbs were patent when animals were killed 5 to 6 months after implant (not significant). Heat-denatured albumin-coated Dacron surfaces have a reduced early thromboreactivity but do not appear to greatly potentiate long-term arterial graft patency.

Value of selective spleen scintigraphy when liver/spleen image shows equivocal spleen defects: concise communication.

A retrospective review was performed to determine the utility of selective spleen scintigraphy (SSS) in the evaluation of equivocal defects on liver/spleen (LS) image. Six of seven questionable features on LS image were classified on SSS to be definite defects in three, and normal in three. Three of seven patients had defects on SSS that were not seen on LS image. The inability of the LS image to exclude or delineate an abnormality in the spleen was attributed to an overlying left lobe of the liver in five, and to technique in one. The SSS is a valuable diagnostic tool in the further evaluation of equivocal spleen defects on LS image, and SSS may demonstrate abnormalities not demonstrated on LS image.