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Biomedical subjects

C R Merritt

Publications and source records attributed to C R Merritt.

At least 37 records · Page 2Linked to original sources
PubMed1992

Immunoperoxidase confirmation of ultrasonically guided fine needle aspirates in patients with recurrent hyperparathyroidism.

Fine needle aspiration (FNA) biopsy in conjunction with ultrasonic definition of nonpalpable masses in the neck region is being used more frequently. Currently available preoperative localization tests have failed, in many instances, to delineate adequately the location of missed adenomas of the parathyroid gland. We describe herein the use of ultrasonically guided FNA of parathyroid tissue with immunoperoxidase confirmation for precise localization of the diseased gland. Three patients with persistent hypercalcemia after exploration of the neck were referred to Ochsner Clinic, New Orleans. In two of these patients, a parathyroid adenoma had been removed, while in one patient no adenoma was found. All patients had elevated calcium (range 10.9 to 11.6 milligrams per deciliter), low phosphorous and elevated parathyroid levels. Preoperative ultrasonography to localize the suspected parathyroid glands was performed, with FNA and immunohistochemical confirmation. Smears confirmed adequate cellular material. Alcohol fixed, Papanicolaou stained and air dried, Wright's and Giemsa stained smears were evaluated for the presence of parathyroid cells by conventional cytologic examination. The Papanicolaou-stained slides were then decolorized in 1 percent hydrochloric acid in 70 percent ethanol. After decolorization, the smears were stained for parathyroid hormone (PTH) in an avidin-biotin complex (ABC) system, using a commercially available ABC kit (Vector Laboratories Inc.). The primary antibody is a polyclonal antiserum generated in rabbits against a synthetic human PTH. Negative controls were obtained from normal thyroid glands. In all three patients, the diseased gland was localized by ultrasound with cytologic and immunohistochemical confirmation, one on the right side and two on the left side. At surgical excision, the adenomas weighed 0.8 and 0.75 gram and the carcinoma, 0.75 gram. In two, intraoperative identification of the diseased gland was aided by ultrasound directed methylene blue injection into the adenoma. During a follow-up evaluation of eight to 24 months, serum calcium had remained normal in two patients, and one patient had become hypocalcemic and required calcium supplements. The preoperative localization allowed a direct surgical approach to the side in question in all patients. Ultrasonically guided FNA in an immunoperoxidase system can be a valuable preoperative localization technique for patients with recurrent hyperparathyroidism, thus avoiding extensive exploration of the neck with the subsequent complications.

Adenoma↗
PubMed1992

Evaluation of peripheral venous disease.

DCI is an excellent method for evaluation of the venous system and has several distinct advantages over other methods. One of the major benefits of DCI, particularly with the addition of capabilities to image slow-flow characteristics of veins, is the ease and rapidity of evaluating the lower extremity veins, including not only the femoral and popliteal system but also the major calf veins. The identification of nonoccluding intraluminal thrombus is enhanced by the additional contrast provided by color-flow imaging. In a similar fashion, flow imaging by scanning through the urine-filled bladder permits excellent visualization of the external iliac veins, and in thin patients the common iliac veins and distal inferior vena cava can be assessed. Thus, DCI permits a more rapid examination with increased diagnostic confidence; it may also permit a more accurate examination. The noninvasive and complication-free nature of the examination recommends it strongly as the primary test, particularly in patients with contraindications to contrast evaluation.

Arm↗
PubMed1992

Doppler color imaging. Abdomen.

Abdominal applications of Doppler ultrasonography are becoming increasingly important as familiarity with Doppler principles and instruments grows. The availability of sensitive duplex and DCI instruments specifically adapted for use in the abdomen and pelvis has stimulated interest in the use of Doppler techniques as a complement to conventional imaging. Although the simultaneous display of tissue and flow information has enhanced the ease of evaluation of vascular abnormalities and increased diagnostic confidence, the role of Doppler is only just beginning to be defined. Since blood flow is a fundamental factor in health and disease, it is hoped that the new information provided by Doppler evaluation of the abdomen will continue to advance the role of ultrasound as a primary diagnostic method as Doppler and color imaging technology mature.

Abdomen↗
PubMed1992

Doppler color imaging. Obstetric and gynecologic applications.

The addition of pulsed and color Doppler has greatly added to the diagnostic potential for obstetric and gynecologic ultrasound. In addition to improved morphologic detail inherent in the use of EVUS, new information is available on perfusion and the physiologic changes associated with the menstrual cycle and early pregnancy. The absence of luteal flow strongly predicts unsuccessful pregnancy outcome in patients undergoing therapy for infertility. This introduces the possibility of more economic use of expensive treatments. Later in pregnancy, DCI aids in the efficient and accurate performance of Doppler spectral sampling and contributes to the evaluation of structural and functional abnormalities of the fetus, umbilical cord, and placenta. Applications in the evaluation of patients with suspected ectopic pregnancy, incomplete abortion, and pseudosac are welcome additions for clinical problems that currently result in many malpractice suits. Finally, the recognition of neovascular flow, especially in the ovary, raises hope for improved and earlier diagnosis of ovarian cancer.

Color↗
PubMed1992

Doppler color imaging. Intraoperative and cranial applications.

In infants normal intracranial vessels may be seen in detail by using DCI. This capability is most useful in the initial or follow-up examination of infants with intracerebral AVMs. Aside from this, few clinically important applications of DCI to image the intracranial vessels have been reported.

Carotid Artery Diseases↗
PubMed1992

Doppler color imaging. Carotid and vertebral arteries.

Duplex sonography and DCI have now become standard modalities for imaging of the extracranial carotid and vertebral arteries. They are equivalent in accuracy to arteriography in the evaluation of flow-limiting stenosis. In addition, the newest scanners all appear to have high-resolution imaging systems capable of characterizing plaque properly. DCI currently leads to more rapid scanning and greater ease in evaluating more difficult patients. The most important advance with DCI will come in the future, when there is better understanding of the significance of the Doppler color-flow patterns now being observed. At present, duplex sonography and DCI remain the only imaging modalities that can evaluate the complete spectrum of abnormalities of the extracranial carotid and vertebral vessels, from minimal stenosis to complete occlusion. As a result, they are valuable tools in the diagnosis of disease.

Carotid Arteries↗
PubMed1991

Roentgenographic evaluation of the augmented breast.

We performed a retrospective study to determine the sensitivity of mammography in detecting breast cancer arising in women with augmented breasts. Of eight women with breast implants in whom breast cancer developed, six had mammograms before biopsy. Only two of the six cancers were identified mammographically (sensitivity = 33%), and one of these two was seen only in retrospect. In both cases, the mammographic findings suggested a benign rather than a malignant process. All eight women had a palpable mass and early disease, and all are clinically disease-free at present. The sensitivity of mammography in detecting palpable cancers in a control group of women without implants was 92% (118 of 128). For tumors of 2 cm or less, the sensitivity was 88% (58 of 66). These results suggest that the sensitivity of mammography in detecting breast cancer is decreased when implants are present. Further investigations are needed to determine the effects of prostheses on mammographic evaluations.

Adult↗
PubMed1991

Doppler US: the basics.

Doppler ultrasonography (US) is an invaluable tool in the diagnosis of occlusive vascular disease and is assuming increasing importance in the diagnosis of abdominal, pelvic, and fetal disorders. The author presents for new users the basic physics principles of Doppler US in his discussions of the Doppler principle, instrumentation, signal processing and display, artifacts, and interpretation of data. An understanding of these principles will assist radiologists in using the full potential of Doppler US in the diagnostic workup.

Ultrasonics↗
PubMed1989

Digital imaging of the chest.

During the past several years, image acquisition in nuclear medicine, computed tomography, ultrasonography, subtraction angiography, and magnetic resonance has been by digitization. Despite these advances, research in the development of digital imaging in conventional radiography has lagged behind. Although studies with a variety of digital techniques have been carried out on several fronts, we still do not possess a method that has captured the imagination of the majority of radiologists and other physicians to a point where it could replace conventional screen-film imaging. This article reviews the current status and general principles of the technology, focusing on the four digital radiographic techniques that have shown the greatest promise - film digitization, an image intensifier - based system, photostimulable phosphor plates, and a scanned projection system. The physical aspects of each of the four systems and the clinical results that have been reported to date, as well as the advantages and disadvantages of each system, are presented.

Humans↗
PubMed1989

Usefulness of duplex ultrasound in evaluating vertebral arteries.

A criticism of duplex scanning of the carotid vessels is that the study is limited to evaluation of the carotid bifurcations, whereas with other vascular imaging studies the vertebral vessels can also be seen. We have prospectively collected data on our ability to evaluate the vertebral vessels on all patients who are sent for carotid evaluations. We have scanned 677 patients and have identified flow in one or both vertebral arteries in nearly 90% of these patients. Therefore, we urge that evaluation of vertebral vessels be made a routine part of the standard carotid duplex ultrasound examination.

Carotid Artery Diseases↗
PubMed1989

MRI of soft tissue vascular malformations.

Magnetic resonance imaging (MRI) is constantly progressing as an important imaging modality for the evaluation of the cardiovascular system and vascular malformations. Due to its superior contrast resolution and sensitivity, MRI is able to differentiate between fat, muscle, bone, and vascular structures. It provides three-dimensional information without the use of ionizing radiation or invasive procedures. We evaluated 11 vascular malformations by MRI using Spin Echo T1 and T2 weighted images. MRI provided more information than computerized tomography, and, in many instances, obviated the need for angiography.

Adolescent↗
PubMed1988

A review of applications of MRI in soft tissue and bone tumors.

Due to excellent soft tissue contrast and multiplanar imaging capability, MRI is assuming a major role in recognition, staging, and treatment planning of soft tissue and bone tumors. Direct sagittal, coronal, and axial images permit assessment of intraosseous and extraosseous extension of tumors and their relationship to the joints and neurovascular structures, and detection of "skip" lesions. MRI allows improved detection of recurrent tumors in the presence of non-ferromagnetic metallic implants as compared to CT. In the evaluation of soft tissue tumors, MRI is more sensitive than CT and allows differentiation among fat, muscle, tendon, bone, and vascular structures based on signal characteristics. Over a period of 18 months, 100 soft tissue masses and bone tumors were evaluated using MRI. Spin echo sequences with T1 and T2 weighted images were most valuable in differentiating normal and abnormal tissues. Calculated comparative measurements of relaxation times showed no reliable difference between benign and malignant tumors.

Adolescent↗