Systematic evaluation of blood clot echogenicity was performed with five different transducer frequencies in two experiments. In the first experiment, blood clots were insonified at five different time periods; from immediately after clotting up to 96 hours after clotting. In the second experiment, blood clots of four different hematocrits (48 to 20%) and clots of hemolysed blood were insonified. The clots, with normal hematocrits, were highly echogenic when imaged with 5, 7.5 and 10-MHz transducers immediately and 24 hours after clotting. The echo intensity decreased over the following days until it almost disappeared at 96 hours after clotting. Clot echogenicity was not observed with 2.25 and 3.5-MHz transducers, except at the interface between retracted clot and serum. Clot echogenicity decreased in proportion with the hematocrit. Hemolysed blood clots were not echogenic. It is concluded from this study that fresh blood clots are echogenic soon after thrombosis with high resolution imaging and this echogenicity diminishes with time. Ultimately with organization and lamination, echogenicity will recur.

High resolution real-time B-mode ultrasound scanning using a sterile 7.5 MHz transducer was performed during operations on the biliary tract. Ultrasound is useful for locating the common bile duct in the presence of acute inflammation and other abnormal anatomy, detecting small calculi in the gallbladder with a thickened wall, measuring the caliber of the common bile duct, and identifying calculi in the common bile duct. Intraoperative ultrasonography can permit earlier and more precise appraisal of operative findings and, thereby, decrease operative time.

The magnetic resonance (MR) imaging features are described in a case of gallbladder carcinoma presenting as a fungating mass associated with gallstones as well as biliary obstruction due to pancreaticoduodenal lymph node metastasis. The MR findings complemented diagnostic observations made on preoperative sonography and computed tomography of the abdomen.

The rational treatment of thyroid diseases requires an understanding of the thyroid function and an accurate evaluation of its functional (endocrine), as well as it morphological alteration. There are several different imaging techniques which are available and are in use in the evaluation of thyroid diseases. In this article we present a protocol for the use of diagnostic imaging to evaluate a focal thyroid mass, a diffusely enlarged gland, regional, and distant metastatic disease. The current diagnostic applications of radionuclide scanning, ultrasound, computed tomography, and magnetic resonance imaging (MRI) will be discussed.