The slit infrahepatic IVC: pathologic entity or normal variant?

A common finding on abdominal ultrasound and CT examinations is variation in the size of the inferior vena cava (IVC). On occasion the infrahepatic IVC even assumes a slit-like appearance. Though commonly related to respiratory change and to the degrees of intra-abdominal pressure, some have claimed the slit-IVC may be an indicator of hypovolemia. To study this phenomenon, we evaluated prospectively the IVC in 26 normal volunteers. These individuals were studied supine by dynamic image ultrasound at end-inspiration, end-expiration, and during the Valsalva maneuver. The size of the IVC was maximal with the patient supine and at end-inspiration (A-P 1.8 cm). The subhepatic IVC decreased in size at end-expiration (A-P 1.2 cm) and frequently collapsed with the Valsalva maneuver (A-P 0.7 cm). Dramatic changes in the size of the IVC with changes in ventilation are normal variants. The use of the slit-IVC to diagnose hypovolemia should be done with caution.

Efficacy of automated biopsy guns versus conventional biopsy needles in the pygmy pig.

Debate over which biopsy needle is the best has intensified recently with the introduction of automated biopsy guns including the 18-gauge long-throw and short-throw Biopty, the 18-gauge Cook, and the 14- and 18-gauge Klear Kut. To evaluate the efficacy of these mechanized biopsy guns versus that of conventional manual biopsy needles in the acquisition of adequate tissue for histopathologic evaluation, open hepatic and renal biopsies were performed in 15 pygmy pigs. The specimens were evaluated separately in a double-blind fashion by two histopathologists using graded criteria. Overall, the best results were obtained with the manual 14-gauge Tru-Cut needle, the long-throw 18-gauge Biopty gun, and the 18-gauge Cook biopsy gun. By comparison, the aspiration-type needles did not perform as well when considered as a group. Several other needles scored well in the biopsy of either the liver or kidney, but not in both. Disappointing results were obtained with the Klear Kut guns (both 14- and 18-gauge) and the Vacu Cut and PercuCut needles.

Informed consent for intravascular administration of contrast material: how much is enough?

To determine the usefulness of informed consent prior to the intravascular administration of contrast material, the authors evaluated four equal groups of patients with different degrees of counseling concerning risks and risk factors. Group 1 was given no information. Group 2 was informed of the common risks in a written statement. Group 3 was informed of all known risks in a written statement. Group 4 was informed of all known risks by means of physician counseling. The average times it took for the technologist (groups 1-3) or the physician (group 4) to counsel the patient and obtain informed consent were 1.7, 6.2, 13.6, and 11.4 minutes, respectively. Counseling by physicians would require approximately 7% of their professional time in a busy radiology department. On a postprocedure test, the patients in groups 1-4 scored on average 38.4%, 68.2%, 63.2%, and 69.8%, respectively. There was no statistical difference in the performance of groups 2-4 on the postprocedure test. If informed consent is to be obtained prior to intravascular administration of contrast material, use of a straightforward written consent form detailing the common risks and risk factors appears to be the best method.

Effect of hydration and dehydration on technetium-99m CO2 DADS renal studies in normal volunteers.

Ten normal volunteers were studied in the hydrated and dehydrated states with the new renal radiopharmaceutical technetium-99m N,N'-bis(mercapto acetyl)-2, 3-diaminopropanoate [( 99mTc]CO2 DADS). The data were used to determine the effect of hydration and dehydration and to determine the normal range in each state. Visual evaluation of the images indicated that the first appearance of tracer in the collecting system was approximately the same in either state, that the concentration of tracer in the collecting system was always higher in the dehydrated state (p less than 0.01), and that the ureters always appeared more segmented in the dehydrated state (p less than 0.01). Quantitative analysis of the images indicated that the kidney to background ratio 1-2 min after injection was somewhat greater in the dehydrated state (13.5 +/- 4.0) than in the hydrated state (9.8 +/- 2.2) (p less than 0.05), that the size of the bladder was always greater in the hydrated state (p less than 0.05), and there was no difference in the amount of tracer in the bladder at 30 min after injection. The results define the normal hydrated and dehydrated [99mTc]CO2 DADS renal study and identify several differences between the two states which can be explained primarily by differences in urine flow rates.