Radiofrequency tissue ablation in the rabbit lung: efficacy and complications.

Rationale And Objectives: We assessed the feasibility and safety of performing percutaneous radiofrequency ablation of pulmonary tissue in rabbits.

Methods: Using an aseptic technique and computed tomography (CT) guidance, insulated 19-gauge aspiration biopsy needles were inserted into the right lower lobe of eight New Zealand White rabbits. Radiofrequency was applied via a coaxial electrode for 6 min at 90 degrees C.

Hepatic imaging with iodinated nanoparticles: a comparison with iohexol in rabbits.

Rationale And Objectives: We evaluated the efficacy of a particulate computed tomography (CT) contrast agent in an animal model of focal liver disease.

Methods: Ethyl ester of diatrizoic acid (EEDA) is an iodinated (89 mg I/ml) nanoparticulate (200 nm) contrast agent intended for intravenous use that is currently undergoing preclinical testing in our laboratory. Focal liver abscesses were created in 11 New Zealand White rabbits.

Tissue ablation with radiofrequency using multiprobe arrays.

Rationale And Objectives: We studied the feasibility of increasing the volume of tissue destroyed by radiofrequency tissue coagulation using multiprobe arrays and defined parameters that determine lesion size and shape.

Methods: Radiofrequency was applied to ex vivo calf liver using arrays of two to five 18-gauge probes for 6 min at 70-90 degrees C. Probe spacing (1-3 cm) and arrangement, as well as the method of radiofrequency application (simultaneous or sequential), were varied.

Percutaneous drainage of subphrenic fluid collections that occur after splenectomy: efficacy and safety of transpleural versus extrapleural approach.

Objective: The purpose of this study was to compare the safety and efficacy of transpleural and extrapleural approaches for draining left subphrenic abscesses in patients who have had splenectomy.

Materials And Methods: Twenty-five patients who had percutaneous catheter drainage (28 drainages) of postsplenectomy fluid collections were studied. Twenty drainages were transpleural and eight were extrapleural.

Tissue ablation with radiofrequency: effect of probe size, gauge, duration, and temperature on lesion volume.

Rationale And Objectives: We evaluated the parameters affecting the size and distribution of thermal tissue damage produced by radiofrequency electrodes.

Methods: Thermal lesions were produced by electrodes connected to a radiofrequency generator in specimens of liver (n = 143) and muscle (n = 20). Various combinations of probe tip exposure (0.

Staging of colon carcinoma using water enema CT.

Objective: To determine the accuracy of water enema CT (WECT) for staging colon carcinoma.

Materials And Methods: Thirty patients with colon cancer, diagnosed by barium enema and/or colonoscopy, underwent preoperative WECT. Dynamic contrast enhanced CT studies were performed after rectal administration of < or = 2 L lukewarm tap water.

Nanoparticulate computed tomography contrast agents for blood pool and liver-spleen imaging.

Rationale And Objectives: We investigated the properties of a group of iodine-containing, insoluble compounds formulated as nanoparticles for use as potential blood pool and liver-spleen contrast agents.

Methods: High-resolution, quantitative computed tomography (CT) was performed prior to and at intervals following the intravenous administration of the contrast agents to rabbits. Time-density characteristics for three organs were evaluated.

Time-lapse quantitative computed tomography lymphography: assessing lymphatic function in vivo.

Rationale And Objectives: Immobility and massage produce different local limb lymph flow rates. We studied their influence on accumulation of radiopaque nanoparticulates in regional lymph nodes of normal rabbits.

Methods: Quantitative lymphography at 10-min intervals was used to follow the transport of subcutaneous (s.

Percutaneous computed tomography lymphography in the rabbit by subcutaneously injected nanoparticulates.

Rationale And Objectives: Surgical lymphangiography is infrequently used in staging cancer because of its inherent limitations. Radiopaque nanoparticulates target lymph nodes draining interstitial tissues and could make percutaneous lymphography feasible.

Methods: Experimental nanoparticulate contrast agent formulations were injected subcutaneously in the forepaw or hindpaw of normal rabbits or rabbits with induced reactive nodal hyperplasia.

Failed metallic biliary stents: causes and management of delayed complications.

Objective: To describe the incidence, management and long-term outcome of metal stent failure in patients with malignant biliary obstruction.

Subjects And Methods: Sixty-nine patients received a total of 93 metallic biliary stents for relief of malignant biliary obstruction. Twenty-nine patients had hilar tumours; 40 had common bile duct tumours.

Abdominal abscess. Imaging and intervention.

The diagnosis and management of patients with abdominal abscesses continue to challenge those involved in imaging and interventional techniques. In this article, the authors discuss the use of ultrasonography and CT scans in the work-up of patients suspected of having abdominal abscesses and describe techniques useful for their management preoperatively.

Cholangiographic segmental anatomy of the liver.

The importance of understanding the Couinaud nomenclature describing hepatic segmental anatomy has been increasingly recognized by practicing radiologists. The normal cholangiographic appearances of the biliary ductal branches, as well as those of their common anatomic variants, are less well known. As percutaneous biliary procedures increase in frequency and complexity, a thorough understanding of this anatomy is of utmost importance.

MR imaging of the liver at 1.5 T: value of signal averaging in suppressing motion artifacts.

Objective: Prior reports have suggested that signal averaging is not as effective as phase reordering for suppressing motion-related artifacts on T1-weighted spin-echo MR imaging of the liver at high field strengths. We hypothesized that with shorter TEs, signal averaging could be effective, and therefore undertook this study to compare signal averaging with phase reordering at 1.5T.

A simplified HyperCard data base for patient management in an interventional practice: experience with more than 4000 cases.

Objective: Tracking of interventional radiology procedures is essential for patients' care, follow-up, and quality management, as well as for fellowship training and accreditation. Computer data-base systems that require time-consuming data entry are difficult to use in a practice that performs 1500 abdominal interventional procedures each year while concurrently doing diagnostic imaging. We proposed that a data base updated with data from existing sources and furnishing information used daily in patient management could be maintained by the radiologists it serves.

US, CT, and MRI of primary and secondary liver lymphoma.

Objective: To describe the imaging findings in patients with pathologically proven hepatic lymphoma.

Materials And Methods: Ultrasound, CT, and MRI studies in 23 patients with primary (11 patients) or secondary (12 patients) liver lymphoma were retrospectively reviewed. All patients had proven non-Hodgkin lymphoma; all imaging studies were obtained within 3 weeks of biopsy.

Gallstones in critically ill patients with acute calculous cholecystitis treated by percutaneous cholecystostomy: nonsurgical therapeutic options.

Objective: Patients with acute calculous cholecystitis require removal of gallstones (generally cholecystectomy), as acute cholecystitis is likely to recur if gallstones are left in situ. The purpose of this study was to assess the role of nonsurgical techniques for treating gallstones in critically ill patients with acute calculous cholecystitis managed by percutaneous cholecystostomy.

Materials And Methods: Twenty-six critically ill patients with complex medical and surgical problems who were in intensive care units underwent emergent percutaneous cholecystostomy for acute calculous cholecystitis.

Efficacy of CT in distinguishing small-bowel obstruction from other causes of small-bowel dilatation.

Objective: Dilatation of the small bowel is a common finding on plain abdominal radiographs. In such cases, it is often difficult to determine if the cause of the dilatation is small-bowel obstruction, paralytic ileus, or another intraabdominal disorder. Accordingly, we studied the efficacy of CT in making this distinction.

Cystic neoplasms of the pancreas: evaluation with endoscopic retrograde pancreatography.

Images from endoscopic retrograde pancreatography performed in 38 patients with cystic pancreatic neoplasms were reviewed to determine whether they might allow differentiation of malignant from benign lesions. Twenty-three patients had histologically proved benign lesions; 15 had frankly malignant lesions. Images were classified into four groups on the basis of the appearance of the pancreatic duct: (a) normal, (b) showing narrowing or draping; (c) showing communication with a cystic space, and (d) showing obstruction.

Hemostatic protein polymer sheath: improvement in hemostasis at percutaneous biopsy in the setting of platelet dysfunction.

To study the effectiveness of the protein polymer sheath (PPS), a device intended to limit hemorrhage caused by percutaneous biopsy, in the setting of platelet dysfunction (which may be an important cause of such hemorrhage), percutaneous biopsies were performed in eight anesthetized pigs: four control pigs and four pigs treated with the experimental aspirinlike drug venopirin. These biopsies were performed with (a) a cutting needle only, (b) the cutting needle equipped with the PPS, and (c) the cutting needle equipped with a thrombin-coated PPS. Needle configuration and biopsy site were randomized.

Bleeding due to needle biopsy: effect of venopirin in an animal model and implications for humans.

Purpose: This study was undertaken to address the effect of platelet dysfunction on bleeding associated with percutaneous needle biopsy.

Materials And Methods: With use of an established animal model, 199 biopsies were performed on the livers of 13 anesthetized pigs (95 on control animals, 104 on venopirin-treated animals). The needles used were 16-22-gauge Chiba type, 18-gauge Tru-Cut, and 18-gauge Menghini.

Measurement of tissue carcinoembryonic antigen levels from fine-needle biopsy specimens: technique and clinical usefulness.

Levels of tissue carcinoembryonic antigen (CEA) in 54 abdominal fine-needle biopsy specimens from 50 patients were measured to ascertain the use of tissue CEA levels in diagnosis of malignancy. Biopsy was performed in the following sites: liver (n = 34), retroperitoneum (n = 8), adrenal gland (n = 3), pancreas (n = 2), omentum (n = 2), pelvis (n = 2), spleen (n = 2), and stomach (n = 1). Histologic findings proved malignancy in 39 patients and benign disease in 11 patients.

Hepatic neoplasms: surgically relevant segmental anatomy and imaging techniques.

With advances in imaging and surgical techniques, the diagnosis and treatment of primary and secondary liver neoplasms have improved. Advances in imaging have contributed to the early detection of the tumors and have allowed more precise preoperative characterization and localization of the lesions. Refinements in surgical technique have permitted more extensive resections, while at the same time placing even greater importance on accurate preoperative imaging of the tumor.