Differentiation of spontaneous canine breast tumors using dynamic magnetic resonance imaging with 24-Gadolinium-DTPA-cascade-polymer, a new blood-pool agent. Preliminary experience.

RATIONALE AND OBJECTIVES: The author assess the enhancement characteristics over time of spontaneous breast tumors in dogs comparing gadopentetate dimeglumine with a new blood-pool agent (24-gadolinium [Gd]-DTPA-cascade polymer). METHODS: Eighteen dogs with spontaneous breast tumors (5 carcinomas, 4 adenomas, and 9 benign mixed-tissue tumors) underwent dynamic magnetic resonance imaging after intravenous injection of gadopentetate dimeglumine and the blood-pool agent. Signal intensity time curves were followed up to 30 minutes after injection of both agents in the same animal. A nonlinear fitting routine enabled calculation of the delivery and clearance half lives of the contrast agent kinetics in each tumor. RESULTS: For gadopentetate dimeglumine, a fast signal increase was found immediately after intravenous injection, with a subsequent signal decay in all tumors. No difference was observed between the enhancement kinetics of different tumor types after gadopentetate dimeglumine application. Similar kinetics were found in benign lesions after injection of the blood-pool agent. However, in carcinomas the blood-pool agent displayed a slower delivery, delayed peak enhancement, and slower tumor tissue clearance or even a signal plateau of more than 30 minutes. CONCLUSIONS: Dynamic magnetic resonance imaging of breast neoplasms using a blood-pool agent may help to better differentiate between benign and malignant lesions because it demonstrates the enlarged interstitial space and increased capillary permeability in carcinomas.

[Maxillary sinus examination after sinus floor elevation combined with autologous onlay osteoplasty]. / Kieferhöhlenuntersuchung nach Sinusbodenelevation kombiniert mit autologer Onlay-Osteoplastik.

BACKGROUND: Complication rates after sinus floor augmentation of up to 10% are mentioned in literature, often when heterologous bone implants are used. The aim of our retrospective study was to determine the complication rate involving the maxillary sinus of patients treated with autologous spongiosa. PATIENTS AND METHODS: In 46 patients with an absolute maxillary atrophy (61% female, 39% male, mean age 49 years), a sinus floor augmentation, if necessary combined with an onlay bone graft of the iliac crest, was performed. Implants (Brånemark) were placed in a two-stage procedure after 3-6 months. Prior to surgery, a panoramic film was made for diagnosis and treatment planning; in addition, a sinus X-ray was taken when disease of the maxillary sinus was suspected. panoramic radiography was routinely taken after surgery. A clinical and radiological follow-up examination was performed after 6-12 months, and the patients answered a questionnaire. This study also included evaluation of operation reports and case histories. Ultrasound as well as magnetic resonance imaging to prevent radiation exposure were performed additionally. RESULTS: In spite of perforation of the maxillary sinus mucosa in about 25%, removal of the bone graft due to inflammation was not necessary. A transient sinusitis developed in 2%. The implant loss rate (3 out of 154) may be called small. DISCUSSION: Even though alternative heterologous graft materials exist, maxillary sinus floor elevation with autologous bone graft is still a safe option. Changes of the maxillary sinus are detectable in a small percentage, relatively often due to preexisting unrecognized or subclinical diseases of the maxillary sinus. Magnetic resonance imaging is, in spite of the high financial and technical effort required, a serious alternative to computed tomography. The combination of autologous bone graft with calcium phosphate ceramics, platelet-rich plasma, or synthetic bone growth factors should be tested as an alternative treatment method.

Dynamic contrast-enhanced MR imaging of the upper abdomen: enhancement properties of gadobutrol, gadolinium-DTPA-polylysine, and gadolinium-DTPA-cascade-polymer.

The enhancement properties of gadobutrol (40 and 80 mumol/kg body weight, 550 daltons), gadolinium-DTPA-polylysine (20 mumol/kg body weight, 53,000 daltons) and gadolinium-DTPA-cascade-polymer (20 mumol/kg body weight, < 30,000 Daltons) were investigated in abdominal MR imaging using a pig model (n = 24). Signal intensities before and after contrast media application were assessed using a fast single slice FLASH sequence. Measurements were made every 4 s within the first 116 s, every minute between 4 and 10 min and after 15, 20, 30, 40, 50, 60, 90, and 120 min after contrast media injection. Injection of gadobutrol resulted in typical signal intensity curves characterizing it as an extracellular agent similar to gadopentetate dimeglumine. Significant enhancement was found in all tissues except the trunk muscles when the lower dose was administered. Gadolinium-DTPA-polylysine injection resulted also in significant enhancement of the liver, the pancreas, and the renal cortex, but not of the trunk muscle, reflecting its blood pool properties known also from other macromolecular contrast agents. The signal intensity curves obtained after gadolinium-DTPA-cascade-polymer injection were similar to those obtained after polylysine injection, stressing the blood pool character of this new type of blood pool agent.