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Biomedical subjects

N Dash

Publications and source records attributed to N Dash.

At least 19 recordsLinked to original sources
PubMed2000

Tubular adenomas of the breast: imaging findings with histologic correlation.

OBJECTIVE: The purpose of this study is to describe the imaging features of tubular adenomas, which are rare benign breast tumors usually found in women younger than 35 years old. CONCLUSION: In young women, tubular adenomas can look like noncalcified fibroadenomas on mammography and sonography. In older women, tubular adenomas may resemble malignant masses with microcalcifications. Awareness of these findings may help in assessing concordance between imaging and histologic findings after percutaneous core biopsy of these rare lesions.

Adenoma↗
PubMed1999

Observer sensitivity to small differences: a multipoint rank-order experiment.

OBJECTIVE: To evaluate observer sensitivity to small differences in image presentation, a multipoint rank-order experiment was used to identify small differences or trends in observations. MATERIALS AND METHODS: Ten observers were presented with 50 sets of breast images that had been compressed at five different levels. Each set contained six images ranging from noncompressed to approximately 101:1 compression. Observers were asked to review all images of a case side by side and rank order the quality of each to enable determination of the presence or absence of masses and clustered microcalcifications. RESULTS: As a group, observers were able to detect small differences among the images, even at the lower compression levels (p < .001). As compression levels and image degradation increased, the ability to identify differences between different modes also increased. Large observer variability in discrimination ability was observed. CONCLUSION: Multipoint rank ordering of images viewed side by side can be an efficient method to identify small differences in image presentation. This approach to image ranking could be used to rule out or confirm the need for objective observer performance-type studies.

Breast Diseases↗
PubMed1999

Usefulness of tissue marker clips in patients undergoing neoadjuvant chemotherapy for breast cancer.

OBJECTIVE: The purpose of this study was to evaluate the usefulness of a tissue marker clip in patients undergoing preoperative chemotherapy for breast carcinoma. MATERIALS AND METHODS: Between June 1996 and July 1998 (26 months), a tissue marker clip was placed in 29 patients with breast carcinoma who showed significant clinical response to preoperative chemotherapy. In these patients, 13 clips were placed stereotactically and 16 clips were placed using sonographic guidance. A retrospective review of these cases was made to evaluate helpfulness of the clip during preoperative needle localization. RESULTS: One patient relocated to another city, so surgical follow-up was available in 28 patients. Twenty-four of these 28 patients required preoperative wire localization and four still had a palpable tumor at the time of surgery. Preoperative wire localization would have been possible without any difficulty in eight patients (28.6%), possible but with some difficulty in six patients (21.4%), and impossible in 10 patients (35.7%) without the clip. Thus, clip placement was valuable in 16 (57.1%) of 28 patients at the time of preoperative needle localization. CONCLUSION: With the newer chemotherapeutic agents, the response of breast carcinoma to preoperative chemotherapy may be dramatic. In some patients, the tumor is no longer visible either on mammography or sonography, thus making the preoperative needle localization difficult or even impossible. By placing a radiopaque marker before the lesion becomes unidentifiable, one can confidently localize the tumor bed at surgery.

Adult↗
PubMed1996

Spiral CT during arterial portography.

Spiral computed tomography (CT) performed during arterial portography offers several advantages compared with portographic studies based on conventional CT technique. Because all hepatic images are derived from a volume data set acquired during a single 24-32-second breath hold timed to coincide with the phase of peak hepatic enhancement, motion artifacts and section misregistration are eliminated and high liver-to-lesion attenuation value differences are present on all sections. These factors, in conjunction with the ability to retrospectively acquire thin, overlapping axial sections, result in improved lesion detection. The ability to produce high vein-to-liver attenuation value differences and two-dimensional multiplanar reconstructions simplifies the identification of hepatic segments and therefore lesion localization. A limitation of all CT portographic methods is the frequent occurrence of nontumorous perfusion defects that, in most cases, demonstrate characteristic locations and appearances. Performing delayed CT following portography is one method by which such pseudolesions may be characterized and differentiated from focal pathologic entities.

Artifacts↗
PubMed1995

Transcranial Doppler sonography. Part 1. Principles, technique, and normal appearances.

Transcranial Doppler sonography is a noninvasive technique that uses a 2-MHz, pulsed Doppler transducer to measure the velocity of blood flow within the circle of Willis and vertebrobasilar system through regions of temporal calvarial thinning or through the orbits or foramen magnum. By using spectral analysis of the Doppler frequency shifts from insonated red blood cells moving through a preselected arterial sample volume, transcranial Doppler calculates and displays the peak systolic and diastolic velocity, the mean velocity, and the pulsatility index of blood flow within the interrogated vessel. Vessel identification is based on standard criteria, including the cranial window used, transducer position, depth of sample volume, direction of blood flow, relationship to the terminal internal carotid artery, and response to common carotid artery compression. Diagnoses made with transcranial Doppler sonography are based on the detection of increased or decreased blood flow velocity, absence of blood flow, or changes in pulsatility.

Blood Flow Velocity↗
PubMed1995

Transcranial Doppler sonography. Part 2. Evaluation of intracranial and extracranial abnormalities and procedural monitoring.

Transcranial Doppler sonography can be used to evaluate a spectrum of intracranial and extracranial vascular abnormalities. It is of proved value in the detection and follow-up of vasoconstriction caused by subarachnoid hemorrhage and can be used to demonstrate significant stenosis or occlusion of basal intracranial arteries and coexisting routes of collateral circulation. Transcranial Doppler sonography can play an important role in the determination of brain death and can be used to identify the nidus of an arteriovenous malformation, along with its major routes of supply and drainage. The technique may provide insights into cerebral hemodynamics following trauma, stroke, or migraine. Use of transcranial Doppler sonography enables a rapid, noninvasive diagnosis of the subclavian steal syndrome, and it is a valuable adjunct to duplex carotid sonography for determining the effect of atherosclerotic lesions of the internal carotid artery on cerebral hemodynamics. In the operating room or angiographic suite, transcranial Doppler sonography can be used to monitor patients undergoing surgical, interventional, or diagnostic procedures for the development of cerebrovascular complications.

Brain Death↗
PubMed1993

Case report 790. Mesenchymal chondrosarcoma of the sacrum.

We have presented a case of mesenchymal chondrosarcoma of the sacrum in a 20-year-old woman. We have emphasized that CT and MR are the best imaging modalities for the assessment of the neoplasm and the surgical decision-making process. Histologic study is mandatory for diagnosis of the tumor, with its characteristic dual pattern of chondroid tissue and undifferentiated mesenchymal cells. The rarity of the neoplasm, its deep pelvic location and nonspecific symptomatology led to a late diagnosis and an unfortunate but necessary sacral amputation resulting in bladder and bowel functional sequelae.

Adult↗
PubMed1990

Intra-aortic counterpulsation balloon pumps: CT appearance.

Intra-aortic counterpulsation balloon pumps (ICBP) used in the setting of cardiogenic shock or high risk cardiac surgery, have been identified on chest films in the inflated state during diastole (1). We report characteristic computed tomography (CT) findings of an inflated ICBP, discuss its radiographically identified complications, and suggest that the presence of this device should be excluded before suspecting other etiologies for intra-aortic gas.

Counterpulsation↗
PubMed1988

Latissimus dorsi cardiomyoplasty: radiographic findings.

Left latissimus dorsi muscle cardiomyoplasty is a surgical procedure in which the muscle is mobilized as a pedicled flap, moved into the left pleural and mediastinal cavities, and used for surgical repair and/or mechanical augmentation of a failing left ventricle. Chest radiographs in four patients who had undergone this procedure were evaluated. In all four patients, there was bandlike or diffuse increase in density in the left midhemithorax with loss of the left heart border. These findings, which could be misinterpreted as lung disease, represent the transposed muscle flap. CT showed the exact anatomic position of the flap in relation to the intrathoracic structures. Familiarity with the postoperative radiographic appearance of this type of myoplasty is important to avoid misinterpretation.

Aged↗
PubMed1987

MRI appearance of esophageal duplication cyst.

Magnetic resonance imaging (MRI) was utilized to demonstrate an esophageal duplication cyst of the midesophagus in a 61-year-old woman. The radiographic, computed tomographic, and MRI features are illustrated.

Esophageal Cyst↗
PubMed1987

Magnetic resonance imaging appearance of primary squamous cell carcinoma of the breast.

Primary squamous cell carcinoma is a rare form of carcinoma of the breast. This article reports on two such lesions with their appearance in magnetic resonance imaging and reviews the scant English literature of the past 10 years. Most of these tumors are circumscribed and have areas of necrosis. The prognosis in patients with this disease is the same as that of adenocarcinoma of the same size and stage.

Aged↗
PubMed1987

Segmental absence of the aortic wall: magnetic resonance imaging sign of aneurysm.

A thin-walled, posttraumatic false aneurysm of the descending aorta in a 32-year-old man was obvious on chest radiography, computed tomography, and aortography. The wall of the aneurysm was not visualized on a magnetic resonance imaging study. However, a segmental absence of the lateral wall of the descending aorta indicated the level of the abnormality. This finding was not observed on 100 consecutive normal aortas studied with gated magnetic resonance imaging. It was observed in 2 of 50 normal aortas on nongated thoracic magnetic resonance imaging.

Adult↗
PubMed1986

Magnetic resonance imaging in acute tendon ruptures.

The diagnosis of acute tendon ruptures of the extensor mechanism of the knee or the Achilles tendon of the ankle may usually be made by clinical means. Massive soft tissue swelling accompanying these injuries often obscures the findings, however. Magnetic resonance imaging (MRI) can rapidly demonstrate these tendon ruptures. Examples of the use of MRI for quadriceps tendon, and Achilles tendon rupture are presented.

Achilles Tendon↗
PubMed1986

Magnetic resonance imaging in the diagnosis of breast disease.

Magnetic resonance imaging (MRI) of the breast was performed in 10 volunteers and 102 women with suspected breast disease, using a 0.35-T superconducting magnet. All patients had prior x-ray mammography. MRI was superior to mammography in differentiating solid from cystic lesions and equivalent to mammography in providing information regarding different parenchymal patterns. Of 21 surgically proven carcinomas of the breast, MRI correctly identified 18 and mammography identified 19. The major disadvantage of MRI is its inability to show calcifications, benign or malignant. Future studies will be needed to show the relative values of sonography and MRI in detecting small cysts. In addition, MRI in future should be able to demonstrate small, noncalcified masses in mammographically dense, fibrocystic breasts.

Adenofibroma↗