Extremity veins: evaluation with fast-spin-echo MR venography.

The authors evaluated a flow-independent magnetic resonance (MR) imaging technique in extremity veins with slow flow that relies on the prolonged T2 of blood to create angiographic contrast. A commercially available heavily T2-weighted fast-spin-echo sequence was optimized for MR venography in volunteer and phantom studies. Good depiction of venous anatomy was routinely obtained with the optimized method. Fast-spin-echo MR venography allowed evaluation of slow-flow systems such as the calf and forearm veins.

Is pre-intervention intravascular ultrasound necessary in evaluating target lesion calcification in patients undergoing transcatheter therapy?

To identify a subset of patients with a high probability of extensive calcification for further intravascular ultrasound (IVUS) examination, the frequency and extent of target lesion calcification as assessed by IVUS and its correlations with age, gender and risk factors as well as the value of angiography in identifying ultrasound calcification were analyzed in 88 patients undergoing balloon angioplasty for significant coronary atherosclerotic stenosis. The extent of calcification was semi-quantitatively graded as 0: no calcification; +: calcification arc < 90 degrees; ++: calcification arc from 90 degrees to 180 degrees; : calcification arc > 180 degrees. The distribution pattern of calcification was classified as superficial, deep or mixed. The results indicate: (1) the frequency of target lesion calcification was 38.6%, of which 52.9% showed a superficial pattern and 56.0% had a calcification arc < 90 degrees; and (2) only age was significantly associated with target lesion calcification in all of the patients. The frequency of calcification was remarkably higher in patients > or = 60 years old than in patients < or = 60 years old (61.9% vs 17.4%, p < 0.001); (3) among patients less than 60 years old, those with calcification had a higher average number of risk factors than those without; and (4) the total sensitivity of angiography in identifying ultrasound calcification was 43.6%, with a significantly higher sensitivity for calcification arc > 180 degrees and mixed pattern. In conclusion, pre-intervention IVUS may be necessary in patients > or = 60 years old and in those < 60 years old with more than two risk factors in selecting devices to optimize interventional strategies.

[The administered activity of radionuclides in nuclear medicine--rational reduction of medical radiation exposure].

A survey of 104 hospitals was conducted to determine the administered activity of radionuclides. Eighty-five hospitals responded, and reported a total of 119,614 examinations in one year. The examinations included: bone scintigraphy, 26.4%; Thallium-201 (201Tl) myocardial scintigraphy, 15.5%; Gallium-67 (67Ga) scintigraphy, 13.3%; N-isopropyl-p-[123I]iodoamphetamine (IMP) brain perfusion scintigraphy, 7.0%. The administered activity was corrected by body weight only for children at more than 80% of the responding hospitals. The number of hospitals that reported over-administration of radionuclide varied according to the type of scintigraphy performed: bone, 76%; inflammatory (67Ga), 93%; myocardial (201Tl), 89.2%; brain (IMP), 8.5%. The administered activity of IMP was closer to the upper limits specified in the Recommendations on Standardization of Radionuclide Imaging by the Japan Radioisotope Association (1987), because IMP is very expensive and is supplied as single vials. The highest average effective dose was for myocardial scintigraphy, the second-highest for inflammatory scintigraphy, and the third-highest for bone scintigraphy. In 201Tl and 67Ga scintigraphy, the entire contents of the vial may be administered two days before the expiration date, because the ratio of (true patient administered activity) to (declared patient administered activity) is similar to the ratio of (radioactivity on the day of supply) to (radioactivity on the day of expiration). The factors that influence administered activity are throughput, price of the radionuclide, and whether the radionuclide is sold as a single vial. In order to decrease the effective dose, it is necessary to establish a close cooperation between medical personnel, the makers of radiopharmaceuticals, and manufacturers of gammacameras.

[Brachytherapy of choroidal melanoma using radioactive gold grains--a case report].

A brachytherapy of a choroidal melanoma using 198Au grains has been performed. Procedurally, the sclera was first incised, after which a pouch was constructed and the grains then arranged around the tumor in a circle so as to enclose it, said operative procedure according to the Manchester Technique. Total Gy dosage amounted to 120 Gy. Postoperatively, in due course, the disappearance of the tumor was clearly shown on MRI examination. The small size and the short half-life of the gold grains made it possible to insert the grains into the tissue permanently, and to give an adequate Gy dosage to eradicate the tumor while still preserving the eyeball.