Tc-99m DMSA renal uptake: influence of biochemical and physiologic factors.

Thirty-eight female Sprague-Dawley rats were studied to determine the effects of (a) tubular blockade and (b) commonly encountered changes in hydration and acid-base balance, on the urinary excretion and renal localization of Tc-99m dimercaptosuccinic acid (DMSA). Ten additional rats were studied to quantitate the in vivo protein binding of Tc-99m DMSA, and a final group of 12 animals was used to quantitate DMSA distribution in animals with diminished functional renal mass. Both osmotic diuresis and dehydration by water deprivation for 24 hr resulted in a plasma clearance of DMSA slower than in control animals. Acid-base imbalances significantly affected the renal accumulation of DMSA, and acidosis was associated with markedly increased background due to increased liver accumulation. The protein-bound portion of Tc-99m DMSA in the plasma was high, reaching 89% within the first 5 min, and rising very slightly (n.s.) ith time. The unbound portion of DMSA had a plasma clearance slightly higher than the GFR. Ablation of large amounts of renal tissue, resulting in significant decreases in GFR. Ablation of large amounts of renal tissue, resulting in significant decreases in GFR, did not significantly affect the renal localization of DMSA in the intact portions of the kidneys. These data demonstrate that commonly encountered changes in acid-base balance and hydration will significantly alter the biologic distribution of Tc-99m DMSA. These factors should be controlled when carrying out clinical studies.

Congenital bronchobiliary fistula: diagnosis and postoperative surveillance with HIDA scan.

Congenital bronchobiliary fistula (CBBF) is an extremely rare anomaly with myriad presentations that often include common bile duct abnormalities. Traditionally, bronchoscopy and bronchography have been used to establish the diagnosis. A full-term neonate with pneumonia and bilious secretions was diagnosed as having CBBF by means of a HIDA scan. Successful repair consisted of a right thoracotomy, high ligation of the fistula via an extrapleural approach, and cholecystography to confirm biliary drainage into the duodenum. The HIDA scan is a safe and efficient means to diagnose CBBF. When used in combination with surgical contrast studies, it provides clear delineation of all variations of this abnormality, enabling one-stage correction.

Atypical scintigraphic presentation of hepatocellular carcinoma.

A hepatobiliary scan was performed on a patient presenting with symptoms of acute cholecystitis. In addition to cystic duct obstruction, there was a focal area of intense uptake in the left lobe of the liver. Additional imaging studies confirmed a solid mass in the left lobe of the liver, which proved to be a hepatocellular carcinoma on surgery.

Metallic ballistic fragments: MR imaging safety and artifacts.

The ferromagnetism of various bullets and shotgun pellets was tested in vitro. Magnetic deflection showed that four of 21 metallic specimens tested (all bullets) demonstrated marked ferromagnetism. Three of these four were made outside the United States; two of the four were known to contain steel, and the other two were reportedly either copper or copper-nickel-jacketed lead bullets (indicating that the ferromagnetism was due to impurities in the bullet jackets or cores). Ferromagnetic bullets readily rotated within a gelatin phantom in response to magnetic torque. Nonferromagnetic bullets and pellets demonstrated only mild to moderate metal artifact during spin-echo and gradient-echo magnetic resonance (MR) imaging. However, all four of the ferromagnetic bullets produced severe MR artifacts and image distortion. MR studies of seven patients with retained bullets, pellets, or shrapnel were reviewed. In six of the seven, only mild MR artifacts were seen. Only intracranial shrapnel (presumably steel) in one patient created significant artifact. All seven patients with retained bullets and shotgun pellets were imaged safely with MR. However, caution should be exercised with MR imaging in the presence of metallic foreign bodies, particularly if they are located near vital neural, vascular, or soft-tissue structures.