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Biomedical subjects

A M Haggar

Publications and source records attributed to A M Haggar.

At least 19 recordsLinked to original sources
PubMed1990

Central pontine myelinolysis and pontine lesions after rapid correction of hyponatremia: a prospective magnetic resonance imaging study.

The rate at which profound hyponatremia should be corrected is the focus of a recent clinical debate. We prospectively studied neurological outcomes with serial magnetic resonance imaging in 13 hyponatremic subjects with serum sodium concentrations of less than 115 mmol/L (mean initial serum sodium concentration, 103.7; range, 93-113 mmol/L). All subjects were corrected to mildly hyponatremic levels at 24 hours and ultimately underwent an increase in serum sodium concentration of 25 mmol/L without development of hypernatremia. Magnetic resonance imaging revealed the development of pontine lesions in 3 patients. The correction rate of hyponatremia over the first 24 hours was significantly faster in patients with pontine lesions (mean +/- SD, 1.25 +/- 0.4 mmol/(L . hr) versus 0.74 +/- 0.3 mmol/(L . hr); p less than 0.05). Initial sodium concentration was also significantly lower in the pontine lesion group (97.3 +/- 6.7 vs 105.6 +/- 5.2 mmol/L, p less than 0.05). We conclude that the correction rate of hyponatremia plays a significant role in the pathogenesis of pontine lesions in individuals with profound hyponatremia who undergo large increases in sodium concentration as a result of severe initial hyponatremia.

Adult↗
PubMed1990

Juxta-articular large cell lymphoma.

Three patients with juxta-articular large cell lymphoma presented as suffering from monarthropathies. A spectrum of radiographic changes was observed that included subchondral sclerosis, regional osteopenia, effusion, and mottled lytic changes in the juxta-articular region of the affected joint. MRI was performed in two patients. In one, it revealed a high signal mass on T2-weighted sequences. In the second, a mass bridging the joint was demonstrated which was difficult to appreciate on CT and was not visible radiographically. In all cases, biopsies revealed large cell non-Hodgkin's lymphoma of bone. We present these studies to emphasize this unusual pattern of non-Hodgkin's lymphoma as well as to demonstrate the contribution of MRI to the diagnosis.

Acromioclavicular Joint↗
PubMed1989

Eigenimage filtering in MR imaging: an application in the abnormal chest wall.

A postprocessing linear filter was applied to spin-echo images on 10 patients with known or suspected chest wall invasion due to bronchogenic carcinoma. This technique known as eigenimage filtering allows selective feature extraction of suspected abnormalities from conventional MR images. The final result is an image with marked increased contrast range through enhancement of a desired process (tumor) with suppression of an interfering process (e.g., normal surrounding tissue). This preliminary work demonstrates the ease with which the technique may be implemented, the contrast enhancement obtained between the desired and the interfering feature in the final eigenimage, and its ability to correct for partial volume averaging effects. Also demonstrated are artifacts that can interfere with the interpretation of the eigenimage and a method for minimizing these artifacts in the final eigenimage.

Carcinoma, Bronchogenic↗
PubMed1989

Primary tumors of the foot: MR imaging.

The findings at magnetic resonance (MR) imaging of eight patients with primary tumors of the foot were compared with those at gross pathologic examination. In all cases, there was excellent correlation between the two studies. When compared with computed tomography (CT), MR imaging was superior in defining the presence and extent of local disease. While the appearances of various foot neoplasms are nonspecific, the ease of multiplanar imaging, the superior contrast resolution, and the sensitivity to marrow abnormalities are major advantages of MR imaging over CT in staging foot neoplasms. These advantages are crucial when foot-sparing curative resection of a malignancy is contemplated. The combination of plain radiography and MR imaging may be all that is necessary for optimal preoperative detection and local staging of tumors of the foot.

Adolescent↗
PubMed1989

Primary malignant giant cell tumor of bone: "dedifferentiated" giant cell tumor.

Well documented examples of primary malignant giant cell tumor of bone (giant cell tumor and concurrent sarcoma arising de novo) are exceedingly rare in the literature. We report a case arising in the left ischium of a 44-yr-old man. He had no previous history of radiation therapy or multiple resections. Histologically, the tumor was a typical giant cell tumor of bone juxtaposed to a malignant fibrous histiocytoma (MFH). The juxtaposition of a high grade sarcoma (MFH) and a locally aggressive nonmalignant neoplasm such as giant cell tumor is analogous to several other tumors of bone and soft tissue in which a low grade malignant or locally aggressive tumor can be associated with MFH or fibrosarcoma de novo, namely chondrosarcoma, chordoma, liposarcoma, and well differentiated intraosseous and parosteal osteosarcoma. The presence of a high grade malignant component in each of the aforementioned neoplasms generally portends a more ominous prognosis, although this is not invariably true. Recognition of the phenomenon of "dedifferentiation" (or tumor progression) in some bone tumors and sarcomas is important to ensure appropriate treatment. Distinction from secondary malignant giant cell tumors which are usually radiation induced is also important, since the latter have a much worse prognosis than those with dedifferentiation occurring de novo.

Adult↗
PubMed1988

Central pontine myelinolysis after rapid correction of hyponatremia: a magnetic resonance imaging study.

We describe a patient with severe hyponatremia (serum sodium 94 mmol/L) who developed encephalopathy and decorticate posturing after a 29 mmol/L rise in serum sodium concentration during the first 24 hours of correction. High-resolution computed tomography of the pons was normal during the first, second, and twelfth weeks of the illness. Subsequent magnetic resonance imaging revealed a pontine lesion consistent with central pontine myelinolysis.

Adult↗
PubMed1988

Meniscal abnormalities of the knee: 3DFT fast-scan GRASS MR imaging.

The ability to use fast-scan techniques to obtain MR images without sacrificing diagnostic accuracy is a desirable goal in MR imaging. We describe a series of patients in whom fast-scan MR imaging was found to be equal to conventional spin-echo imaging in the detection and characterization of meniscal abnormalities. Thirty-five patients with suspected meniscal tears were studied with fast-scan imaging (3DFT-GRASS), and the results were compared with those of conventional spin-echo imaging. Three-millimeter contiguous sections through the entire knee were obtained in 5 min by using the 3DFT-GRASS technique. 3DFT-GRASS and spin-echo images agreed in all cases regarding the presence or absence of an abnormality and its degree of severity. We conclude that fast-scan 3DFT-GRASS MR imaging is useful when screening the knee for the presence of meniscal abnormalities.

Humans↗
PubMed1988

MR imaging strategies in primary and metastatic malignancy.

This article gives the rationale of the indications for the use of MRI in the evaluation of primary and metastatic malignancies of the neck, chest, abdomen, male and female pelvis, and musculoskeletal system. The imaging protocols for each of these areas is also included.

Abdominal Neoplasms↗
PubMed1987

Chest-wall invasion by carcinoma of the lung: detection by MR imaging.

Nineteen patients with bronchogenic carcinoma were studied by MR imaging to determine the presence of chest-wall invasion. All studies were carried out at 1.5 T, and the results were correlated with chest radiographs or CT scans. All MR studies were interpreted before surgery (13 cases) and without knowledge of the results of other radiologic studies. MR findings indicative of chest-wall invasion included a high-signal focus within the chest wall and/or chest-wall thickening with increased signal on spin-echo (SE) images having a repetition time of 2500 msec and an echo time of 50-100 msec (SE 2500/50-100). In one case, noncontour-deforming high-signal intensity within chest-wall musculature (but no other abnormality) was demonstrated on SE 2500/50-100 images. Coronal or sagittal imaging facilitated identification of tumor contiguity with extrathoracic structures in apical lesions. Contrast differences between normal and invaded chest wall on T2-weighted images were the most helpful in assessing chest-wall involvement. These preliminary observations indicate that MR imaging is useful in the evaluation of chest-wall invasion by carcinoma of the lung.

Adenocarcinoma↗
PubMed1985

A reappraisal of upper gastrointestinal response to low-dose glucagon.

Although glucagon is the most commonly used pharmacologic agent for gastrointestinal studies, its exact effects on upper gastrointestinal examinations have not been properly elucidated. A large study by our group did redemonstrate glucagon's significant effect on gastrointestinal motility. However, gastric distention and coating are not improved by glucagon, nor does it have a predictable effect on gastric emptying. Duodenal visualization does appear to be enhanced by the drug. Patient age, weight, and sex are not significant factors in glucagon's response, although they are variables that have an effect on UGI examinations. This article will review physiologic considerations in upper gastrointestinal examinations, with emphasis on glucagon's pharmacodynamics.

Age Factors↗
PubMed1985

Magnetic resonance imaging of the genitourinary tract.

Magnetic resonance imaging, in general, is in a state of evolution. This article demonstrates its potential use in the diagnosis of genitourinary pathology. Controlled studies will be required, however, in order to determine the place of this imaging modality in the vast array of imaging options currently available to the radiologist and urologic surgeon. It is expected that, in the not too distant future, the indications for magnetic resonance imaging in the diagnosis of genitourinary disorders will become clear.

Adrenal Gland Neoplasms↗