Comparative myocardial uptake of technetium-99 m sestamibi and technetium-99m tetrofosmin one hour after stress injection.

Technetium-99m sestamibi and 99mTc-tetrofosmin are at present the preferred tracers for simultaneous assessment of myocardial perfusion and function by gated single-photon emission tomography (SPET). The aim of this work was to compare sestamibi and tetrofosmin myocardial uptake 1 h after stress injection. Consecutive unselected patients were studied either with sestamibi or with tetrofosmin on a random basis, until at least 100 patients had been enrolled for each gender and tracer. Stress was obtained by dipyridamole or exercise or combined dipyridamole + exercise; in the latter cases, exercise was sustained for at least 1.5 min after tracer injection. Injected activity was similarly adjusted to body weight. For each patient, imaging began 60-75 min after injection. All SPET projections were summed; due to the acquisition technology ("roving zoom", i.e. a mobile zoom), the heart always appeared at the centre of the frame in all projections and in the sum image. Thus minimal lung background contamination could be assumed in an elliptic region of interest placed over the heart on the sum image. Three indexes were analysed: total myocardial counts (Sum), mean myocardial pixel (Mean) and maximum myocardial pixel (Max). Four patient groups were analysed: males with sestamibi or tetrofosmin (MS: n = 189 and MT: n = 157), females with sestamibi or tetrofosmin (FS: n = 101 and FT: n = 104). MS and MT groups were comparable for physical variables, maximum heart rate and stress type, as were the FS and FT groups. Sum, Mean and Max were significantly higher with sestamibi (P = 0.0001 by ANOVA). Comparing MS vs MT and FS vs FT, mean values +/- SD were as follows: for Sum (kcounts) 750+/-184 vs 652+/-166, and 707+/-202 vs 594+/-189; for Mean (counts) 4517+/-1171 vs 4107+/-898, and 4908+/-1119 vs 4144+/-1025; and for Max (counts) 6471+/-1654 vs 5794+/-1312, and 7318+/-1886 vs 6152+/-1684. The mean gain with sestamibi was +15%, +10% and +12% in males, and +19%, +18% and +19% in females. Similar differences were found within each stress type subgroup. No gender-specific effect was found for Mean, so the overall mean gain was calculated for Mean: +13% for sestamibi vs tetrofosmin. These findings are consistent with other published smaller sample series. Possible differences between tracers with regard to residual activity in syringes were ruled out by an additional experiment. In summary, we found significantly higher myocardial counts with sestamibi than with tetrofosmin, in males as well as in females.

[Preventive value of intravesical thiotepa on the recurrence of Ta-T1 vesical tumors treated by conservative surgery. Apropos of 247 cases a mean follow-up of 88 months]. / Valeur prophylactique du thiotepa intra-vésical sur les récidives des tumeurs vésicales Ta-T1 traitées par chirurgie conservatrice. A propos de 247 cas suivis avec un recul moyen de 88 mois.

The retrospective homogeneous study of 247 patients with follow-up from 12 months to 384 months (mean 88 months) and managed with or without intra-vesical instillations of thiotepa as prophylactic chemotherapy after surgical conservative treatment is compared with some literature's data principally multicentric randomized series. Statistics contradictions remain with no significative results for possible progression towards infiltration, better "free interval" between recurrences, and better recurrence rate for 100 patients/months. In this series the number of tumors recurrences in each bladder was evaluated: this mean rate of tumors recurrences/year is 1,7 without prophylactic thiotepa and only but always 1,08 with thiotepa. Prophylactic instillations chemoprophylaxy seems to be justified but must be emphasized: mitomycin C, BCG therapy would be better in the future?

Nycthemeral variations of 99Tcm-labelled heparin pharmacokinetic parameters.

Six healthy volunteers (5 males and one female) received four i.v. boluses of 160 U.I. of 99Tcm-heparin at 8.00, 14.00, 20.00 and 02.00 hours at seven-day intervals. Nine blood samples were taken covering a period of 2 h after administration. Simultaneously urine was collected and diuresis was noted. Plasma and urinary radioactivity were measured and standard pharmacokinetic parameters were calculated. Nycthemeral variations of these kinetic parameters were detected by means of distribution-free tests. Circadian rhythms (period = 24 h) were analysed by means of the cosinor method and the Gauss-Marquardt method. The mean raw value of the following parameters: apparent volume of distribution, plasmatic clearance and extra-renal metabolic clearance, increased significantly between 8.00 and 14.00 (p less than 0.01) and decreased between 14.00 and 20.00 (p less than 0.05). A circadian rhythm was found for the plasmatic clearance only (p less than 0.04). On the other hand the elimination half-lives and the renal clearance were unaffected by the time of the injections. These results obtained for low doses of 99Tcm-heparin suggest a circadian rhythm of the bio-availability of heparin in man. This fact should be taken into account for the use of 99Tcm-heparin in the diagnosis of deep-vein thrombosis and for the safe adjustment of the heparin dosages in the treatment of severe thromboembolism.

[Investigation of biliodigestive anastomosis with the help of radiopharmaceutical products]. / Exploration des anastomoses bilio-digestives à l'aide des produits radiopharmaceutiques.

Hepatobiliary investigation using 99mTc-diethyl-iminodiacetic acid (IDA) has permitted a new point of view about the morphological and functional investigation of the biliary-digestive anastomosis. Our clinical study concerning 31 patients (13 choledochoduodenostomies 10 hepaticojejunostomies, 6 choledochojejunostomies and 2 cholecystojejunostomies) helped to specify scintigraphic imaging (stasis in intrahepatic bile duct, reflux in stomach, strangulation phenomenon on the level of the mesocolon, incomplete or complete obstruction). The problems associated with current diagnostic procedures are discussed and we place the scintigraphic method amongst other radiologic methods (barium meal, endoscopic retrograde cholangiography and percutaneous transhepatic cholangiography). This non-invasive diagonostic procedure plays a leading part in the investigation of the biliary digestive anastomosis, and particularly in the hepatico-jejunostomies.

Plasma transport of 99mTc-p-butyl-IDA.

Plasma transport of 99mTc-p-butyl-IDA was measured by four in vitro methods: trichloroacetic acid precipitation, electrophoresis, HPLC, and Scatchard binding isotherm. The data are in accord with protein transport, the main carrier being albumin with two categories of sites. This work suggests that after IV injection of 99mTc-p-butyl-IDA in humans plasma protein binding is one of the limiting factors for the hepatic deposition of the radiopharmaceutical.