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Biomedical subjects

G C Dooms

Publications and source records attributed to G C Dooms.

26 records · Page 2Linked to original sources
PubMed1985

Bone marrow imaging: magnetic resonance studies related to age and sex.

Measurements of T1 and T2 relaxation values and spin density of the lumbar vertebral bone marrow were performed in 212 patients, and the results were correlated with the patients' age and sex. T1 and T2 relaxation times for bone marrow in the lumbar vertebral bodies showed a progressive decrease with age for both sexes (except for the T2 relaxation values in female patients). The replacement of hematopoietic marrow by fatty marrow could explain the decrease in T1 and T2. The T1 and T2 values were in the same range for the first two age groups (age 1-10 years and age 21-40 years) and became slightly greater for the older female patients (age 51 years and older) than for the older males. This could be due to the loss of bone and mineral content, which is more rapid and significant for women. These normal T1 and T2 values may provide a baseline for future evaluation of diseases involving the lumbar spine.

Adolescent↗
PubMed1985

Characterization of lymphadenopathy by magnetic resonance relaxation times: preliminary results.

The purpose of this study was to evaluate the ability of magnetic resonance (MR) to enable characterization of disease within lymph nodes and differentiation between benign and malignant lymph nodes. Ninety-three patients were examined. Normal and malignant lymph nodes were excised from seven patients, and the T1 and T2 relaxation times were analyzed in vitro using spectroscopy. In 86 patients, T1 and T2 relaxation times of the lymph nodes were determined from MR images. Spectroscopic analysis revealed an increase in the T1 and T2 values of nodes involved by neoplasm compared with uninvolved nodes in an individual case. Comparison of measurements from 28 lymph nodes analyzed in vitro using spectroscopy showed an overlap of the T1 and T2 values between normal and malignant lymph nodes. T2 relaxation times and relative spin density values were greater for acute inflammatory nodes than for nodes involved by granulomatous diseases (tuberculosis and sarcoidosis) or nodes replaced by lymphoma or metastasis. Changes in T1 relaxation values were not specific. The measurements of T1 and T2 relaxation times and relative spin density showed an overlap between nonspecific lymphadenopathy, nodes involved by granulomatous diseases, and malignant nodes. Differentiation between these various nonacute types of enlarged lymph nodes could not be achieved using current MR parameters.

Adolescent↗
PubMed1985

Lipomatous tumors and tumors with fatty component: MR imaging potential and comparison of MR and CT results.

This retrospective study was performed to assess the potential of magnetic resonance (MR) imaging for demonstrating various types of lipomatous tumors and tumors with fatty component and to compare the results of MR with those of computed tomography (CT). MR examinations of 17 patients with 18 lipomatous tumors (16, benign; two, liposarcoma) and two patients with fibrosarcomas were reviewed; CT scans were available for comparison in all patients. In the 16 benign lesions (12 benign lipomas, two ovarian dermoid cysts, and two renal angiomyolipomas), the fatty component of the tumors was readily demonstrated by both MR and CT. The T1 and T2 relaxation times and spin density of benign lipomatous tumors were in a range similar to those of normal subcutaneous fat. Differentiation between lipomas and liposarcomas was achieved with both MR and CT. On MR images using a short repetition time (TR = .5 sec), liposarcomas (long T1) were imaged with a lower MR intensity than lipomas (short T1).

Adolescent↗
PubMed1984

Magnetic resonance imaging of the lymph nodes: comparison with CT.

This retrospective study of 144 patients was made to (a) assess the potential of magnetic resonance (MR) for demonstrating lymph nodes using spin-echo technique, (b) compare the MR results with those of CT, and (c) determine the optimal pulse-sequence interval (TR) and echo-delay time (TE) for imaging lymph nodes. The reported CT findings on normal lymph nodes were compared with MR findings in 60 patients who underwent MR imaging of the neck (20 patients), chest (20 patients), abdomen (10 patients), and pelvis (10 patients) for conditions other than lymph node disease. The results showed that CT is presently better than MR for imaging neck and abdominal lymph nodes less than 13 mm in diameter. The ability of MR to demonstrate normal-size (less than 10 mm) lymph nodes in the chest was comparable to that of CT. In addition, MR scans of 84 patients with proven abnormal lymph nodes (8 neck, 49 chest, and 27 abdomen and pelvis) were assessed: in 72 patients, these nodes had also been imaged by CT. MR and CT gave similar results with abnormal lymph nodes (greater than 13 or 15 mm), but MR displayed these nodes better because of its excellent soft-tissue contrast resolution. MR can clearly differentiate abnormal lymph nodes from normal fat, muscle, vessels, adult thymus, thyroid, and diaphragmatic crura, as well as from primary tumor and lymphoceles. Optimal demonstration of lymph nodes with MR required two sequences: one with a short TR and one with a long TR and long TE. Preliminary results indicate that MR holds great promise for the demonstration of lymph nodes in every part of the body.

Adolescent↗
PubMedDate not supplied

MR imaging of intramuscular hemorrhage.

This retrospective study was performed to (a) analyze the appearance of normal striated muscle using the spin echo (SE) technique and (b) evaluate the potential of magnetic resonance (MR) imaging for demonstrating intramuscular bleeding. Magnetic resonance examinations of 30 patients imaged for reasons other than muscular disorders were reviewed. Normal striated muscle was always imaged with a lower intensity than fat because muscle had a longer T1 and a shorter T2 than fat. Furthermore, the spin density of muscle was less than that of fat. The best contrast between the two tissues was obtained with a short repetition time (TR) of 0.5 s and a long echo time (TE) of 56 ms. In addition, five MR examinations from three patients with intramuscular bleeding were assessed. In one case the CT examination was also available for comparison. In every case MR permitted the diagnosis and demonstrated the precise extent of intramuscular bleeding and its regression after therapy. The MR diagnosis of intramuscular bleeding was readily performed because of the excellent contrast resolution of the technique. These lesions were always brighter than the surrounding normal muscle. The optimum SE technique, which enhanced contrast between the muscle and the site of bleeding, was a long TR of 2.0 s and a long TE of 56 ms. The T1 and T2 relaxation times of intramuscular bleeding were always longer than those of normal striated muscle. Preliminary results indicate that MR is very sensitive for the demonstration of intramuscular bleeding.

Adolescent↗
PubMedDate not supplied

MR imaging of cardiac thrombi.

This retrospective study of 10 magnetic resonance (MR) examinations in patients with cardiac thrombi (eight in left ventricle and two in right atrium) was performed to assess the ability of MR for demonstrating cardiac thrombi and describe the appearance of cardiac thrombi using the spin echo technique. Cardiac thrombi usually had higher signal intensity than the normal myocardium on MR imaging, especially on the second echo (TE of 56 or 60 ms) image. Differentiation between cardiac thrombus and intracardiac signal resulting from slowly flowing blood was possible based on different signal intensity changes using various techniques. In conclusion, MI imaging constitutes another noninvasive modality for the detection of cardiac thrombus. Further work is needed to determine its accuracy compared with that of two-dimensional echocardiography.

Adult↗