The occurrence of a coronary spasm after an adenosine stress test is an exceptional event. We report a vasospasm in a patient with normal coronary angiography. The spasm occurred shortly after termination of adenosine infusion on abrupt withdrawal of vasodilation. Ischaemia induced ventricular arrhythmia (bursts of polymorphous tachycardia) that responded well to antispastic therapy. The main identified predisposing factor for coronary spasm was vasospastic angina and adenosine acted as a revealing factor of this unsuspected diagnosis.
An increased prevalence of mitral valve prolapse has been found in Graves’ disease and a common autoimmune etiology has been suggested for both disorders. We investigated the prevalence of mitral valve prolapse in 87 patients with autoimmune chronic lymphocytic thyroiditis, 50 patients with nongoitrous hypothyroidism and 111 healthy control subjects. Mitral valve prolapse was found in 16.09% of patients with chronic lymphocytic thyroiditis compared to 6 and 5.4% in nongoitrous hypothyroidism and normal controls, respectively. The result is statistically significant, p < 0.02, and confirms that the prevalence of mitral valve prolapse is significantly increased in patients with autoimmune disorders of the thyroid gland, when compared to normals and nonautoimmune conditions.
A high radiochemical purity (RCP) is recommended for radiopharmaceutical compounds used in the clinical practice of nuclear medicine. However, some preparations of 99m Tc-sestamibi contain excess impurities (.6%). To understand the origin of these impurities, we investigated the effect of sodium nitrate on the RCP of sestamibi preparations by testing eluates from 3 commercially available 99m Tc generators. Methods: The sestamibi kits (Stamicis) were reconstituted with 99m Tc eluate from nitrate-containing wet-column (NCWC), nitrate-free wet-column (NFWC), and nitrate-free dry-column (NFDC) generators. Sodium nitrate was 0.05 mg/mL in eluates from the NCWC generators. The RCP was determined using aluminum oxide sheets as the stationary phase and absolute ethanol as the mobile phase. Succimer, tetrofosmin, oxidronate, exametazine, albumin nanocolloid, and soluble albumin were also tested for their RCP values with eluates from the 3 different 99m Tc generators. Results: The RCP assessment of 99m Tc-sestamibi was performed on 127 Stamicis preparations. Significantly lower RCP values were found for Stamicis kits prepared with the NCWC generator than for Stamicis prepared with the NFWC (P , 0.0001) and NFDC (P , 0.0001) generators. The number of Stamicis preparations with an RCP under 94% was greater with the NCWC generator (32 of 53 kits) than with the NFDC (2 of 51 kits) or NFWC (0 of 23 kits) generator. Furthermore, the addition of a 0.05 mg/mL concentration of nitrate in NFWC generator eluates significantly decreased the RCP of the Stamicis preparation. In the absence of nitrate in 99m Tc eluate, no difference was observed between the RCP values of Stamicis kits prepared with the NFWC and NFDC generators. The 99m Tc impurities generated by nitrates did not modify the quality of myocardial imaging (normal heart-to-lung ratio, 2.2), probably because these impurities are not in the heart field of view. No other tested 99m Tcradiopharmaceutical interfered with nitrates. Conclusion: We recommend using nitrate-free generator eluates in 99m Tc-sestamibi preparations to improve the product quality and prevent unnecessary exposure of the patient to radiation. Sest amibi labeled with 99m Tc ( 99m Tc-2-methoxyisobutylisonitril, or MIBI) is a lipophilic cationic complex originally developed as a myocardial perfusion imaging agent (1-4) and subsequently used for parathyroid (5) and tumor (6) imaging. Ninety-five percent of intracellular 99m Tc-sestamibi is retained in the mitochondria. Its uptake involves a passive distribution across plasma and mitochondrial membranes, but its retention depends mainly on the large negative transmembrane potential of mitochondria (7). 99m Tc-sestamibi is also a transport substance recognized by the multidrug resistance-related P glycoprotein, and its tumor cell accumulation is enhanced by inhibition of the efflux transport function. This property provided the basis for clinical studies that investigated the role of 99m Tc-sestamibi in predicting the response to chemotherapy in patients with ca...
We describe a new thin-layer chromatography (TLC) method to evaluate the radiochemical purity of 99Tc(m)-tetrofosmin without the drawbacks of toxicity, solvent ratios and time requirement associated with the standard TLC method. The new method uses miniaturized instant TLC plates impregnated with silica gel (ITLCTM/SG, 2.5 x 10 cm) for the stationary phase and 2-butanone for the mobile phase. The standard TLC method was performed with ITLCTM/SG plates (5 x 20 cm) and dichloromethane/acetone (65:35, v/v). Thirty five preparations were analysed by both methods with a storage phosphor imaging system to determine the percentages of hydrolyzed-reduced 99Tc(m) compound (99Tc(m)O2), 99Tc(m)-tetrofosmin and free 99Tc(m)-pertechnetate (99Tc(m)O4(-)). Using the miniaturized TLC method, 99Tc(m)-tetrofosmin had a mean Rf value of 0.55 (standard deviation, 0.05), while 99Tc(m)O4(-) migrated with the solvent front (Rf=1) and 99Tc(m)O2 remained at the origin of the strips (Rf=0). No significant difference was found between miniaturized and standard TLC methods for the radiochemical purity of 99Tc(m)-tetrofosmin using the Wilcoxon matched-pair signed-rank test (P=0.82). Furthermore, the two methods showed a good correlation as measured by the Spearman rank coefficient (r=0.89) and were in perfect agreement, with a kappa index of +1, for a cut-point between positive and negative set at 90%. In conclusion, the results indicate that the miniaturized TLC method is effective for the routine evaluation of the radiochemical purity of 99Tc(m)-tetrofosmin, without some of the drawbacks of the standard method.
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