PubMed Health⌕ Search

Biomedical subjects

R G Schmidt

Publications and source records attributed to R G Schmidt.

15 recordsLinked to original sources
PubMed1996

Metabolic characterization of human soft tissue sarcomas in vivo and in vitro using proton-decoupled phosphorus magnetic resonance spectroscopy.

We applied 1H-decoupling and nuclear Overhauser enhancement to obtain well-resolved 31P magnetic resonance spectra accurately localized to 20 soft tissue sarcomas in vivo, using three-dimensional chemical shift imaging. Fifteen spectra had large phosphomonoester signals (21% of total phosphorus) that contained high amounts of phosphoethanolamine (compared to those of phosphocholine) but no signals from glycerophosphoethanolamine, and glycerophosphocholine was detected in only four cases. Prominent nucleoside triphosphates (52% of phosphorus) and low inorganic phosphate (10% of phosphorus) indicated that a large fraction of these 15 sarcomas contained viable cells, and this impression was confirmed histologically in 13 of the sarcomas. High-resolution in vitro 31P spectra of extracts of surgical specimens of four of the sarcomas studied in vivo and six additional sarcomas confirmed the in vivo assignments of metabolites and revealed considerable inter- and intratumoral variations of metabolite concentrations associated with histological variations in the relative amounts of cells and of matrix materials or spontaneous necrosis. Seven sarcomas, all high grade with pleomorphic or round cells rather than spindle cells, contained an unidentified phosphodiester signal in vivo; its absence in the extract spectra indicates that it may be from an abnormally mobile membrane component. We have documented a means to obtain new information about in vivo metabolism in human sarcomas and to provide a basis on which to examine the uses of 31P magnetic resonance spectroscopy in the clinical management of sarcomas.

Adult↗
PubMed1993

Aneurysmal bone cyst.

Key findings that aid in the diagnosis of an aneurysmal bone cyst are: 1) typically the patients are young individuals less than 20 years old; 2) an expansile bone lesion is bordered by a thin, low signal intensity rim mass; 3) the lesion is inhomogenously increased in signal on T2-weighted images; and 4) multiple fluid-fluid levels are seen with the mass on T2-weighted magnetic resonance imaging scans.

Adult↗
PubMed1989

Magnetic resonance imaging and magnetic resonance spectroscopy of bone tumors and bone marrow disease.

The authors have made use of an integrated magnetic resonance imaging/spectroscopy (MRI/MRS) examination to study seven patients with a variety of bone tumors. The spatial localization method used in the 31P portion of the examination was surface coil localization and a one-dimensional chemical shift imaging method (3 cases). The authors found that the precision of spatial localization was critical in many of these cases, since most of these bone tumors were surrounded by muscle tissue that contained high concentrations of phosphocreatine (PCr). For this reason, they suggest that the metabolite ratios should be referenced to the adenosine triphosphate (beta-NTP) resonance rather than PCr. The phosphate monoester (PME) to beta-NTP ratio was elevated as compared with normal muscle in all of the bone tumors studied. The authors found that all of these tumors exhibited pHs between 7.0 and 7.2, which are similar to the values found for normal muscle. They also show the feasibility of using a line-selective proton chemical shift imaging sequence with high spatial resolution for investigating changes in the fatty composition of bone marrow. This method is illustrated in an example of a patient with advanced avascular necrosis in the femoral heads.

Adolescent↗
PubMed1987

The magnetic resonance imaging appearance at 1.5 tesla of cartilaginous tumors involving the epiphysis.

Three cases of lytic, calcified epiphyseal lesions with plain film and computed tomography features suggestive of chondroblastoma were imaged by magnetic resonance imaging. Histopathologic correlation was obtained in each case. Two cases of chondroblastoma showed low signal intensity on both short (TR600/TE20ms) and long (TR2500/TE80ms) spin echo (SE) images. The third case, a clear cell chondrosarcoma, demonstrated increased signal intensity on moderately T2 weighted (TR2500/TE40ms) images. These findings suggest that magnetic resonance imaging may be helpful in distinguishing these lesions.

Adolescent↗
PubMed1987

Supracondylar fracture of the femur following prosthetic knee arthroplasty.

Sixty-one supracondylar fractures above prosthetic knee replacements in 58 patients were reviewed with a mean follow-up time of 3.7 years (range, 9 months to ten years). The mean interim between arthroplasty and fracture was 2.9 years (range, intraoperative to ten years). Twenty-seven cases demonstrated notching of the anterior femoral cortex. Seventeen patients suffered from a severe neurologic disorder. Group A consisted of 30 patients with 31 fractures treated by open reduction and internal fixation or revision arthroplasty. Follow-up study revealed 25 unions, three malunions, one nonunion, and two above-knee amputations for deep sepsis. Four of 31 patients had increased pain levels or change in ambulatory status postoperatively. Group B consisted of 30 fractures in 28 patients treated by casting alone or traction followed by cast bracing. Follow-up examination showed 17 unions, seven malunions, and six nonunions. Fifteen of the 30 patients had increased pain levels or change in ambulatory status after treatment. Casting produced significant decreases in motion in both groups. The results indicate that this fracture is associated with anterior notching of the femoral cortex and preexisting neurologic disorders. Patients with a supracondylar fracture following prosthetic knee arthroplasty are best managed by secure internal fixation and early motion.

Aged↗
PubMedDate not supplied

MRI diagnosis of biceps tendon rupture.

Distal biceps tendon rupture is a rare injury. While plain radiographs are usually not helpful in visualizing the defect, evaluation of the tendon with MRI has proven to be useful as it depicts complete anatomic detail of the tendon and associated structures. Its multiplanar imaging capability and superior soft tissue contrast resolution makes MRI a prime diagnostic tool in the diagnosis of tendon disorders. We report a case of complete rupture of the biceps tendon diagnosed by MRI.

Adult↗
PubMedDate not supplied

Management of extremity metastatic bone cancer.

It is important to have an aggressive and appropriate treatment program for patients with metastatic cancer to bone. Metastasis to bone should no longer be considered the beginning of the end. It should be an invitation for appropriate orthopedic oncologic involvement and management. Impending pathologic fractures of the long bones can be quickly and relatively easily managed with intramedullary rod fixation. Patients with adenocarcinoma should be monitored periodically to identify the focus of metastatic lesions early. Patients with large lesions previously considered disastrous can be managed successfully using modular oncology systems. Patients with metastatic cancer to bone deserve evaluation and management by orthopaedic oncologists familiar with their treatment.

Bone Neoplasms↗
PubMedDate not supplied

Giant cell tumor of tendon sheath.

The authors present two case studies of giant cell tumor of tendon sheath. This uncommon lesion of the lower extremity is presented in these two cases in correlation with clinical, radiographic, and intraoperative findings. After the pathologic diagnosis was made, the patient in the first case decided not to have the tumor resected. This patient's postoperative course continues uneventfully without expansion of the tumor. In the second case, a local recurrence was noted 13 months after en bloc resection. A review of the literature shows that treatment modalities for such lesions range from marginal excision to radiation therapy. The authors wish to emphasize the high risk of local recurrence of these tumors. Early marginal resection is the treatment of choice.

Adolescent↗
PubMedDate not supplied

MR imaging of osteoid osteoma of the talus.

Magnetic resonance (MR) imaging of the painful ankle of a 15-year-old boy revealed the nidus of a subarticular osteoid osteoma of the talus along with markedly abnormal signal intensity in the neighboring bone marrow. This MR appearance correlated with alterations in the neighboring bone marrow documented by histopathologic examination.

Adolescent↗
PubMedDate not supplied

Combined MR imaging and spectroscopy of bone and soft tissue tumors.

Twenty-three patients with bone and soft tissue tumors were studied with combined magnetic resonance (MR) imaging and spectroscopy. The MR examinations were utilized to determine the size, internal characteristics, and relationships of the tumor to the surrounding tissues. They also determined the optimal placement of the surface coil. The surface coil profile was the localization technique utilized. Four patients were also studied with one-dimensional chemical shift localization. Tumors were grouped according to histologic type, degree of muscle contamination, size, and extent of necrosis. Quantitative comparison among the groups was carried out by comparing the mean ratios of the low-energy phosphate portion of the spectra [phosphomonoester (PME), Pi, phosphodiester (PDE)] to beta-nucleotide triphosphate (NTP). Tumor spectra typically showed a relative elevation in PME, Pi, and PDE and a relative decrease in phosphocreatinine. No characteristic spectra were observed for individual tumor types. Contamination of the tumor spectra from surrounding muscle impaired interpretation of the spectral data. Tumor size and extent of necrosis were important determinants of the relative degree of abnormally elevated metabolite peaks (PME, Pi, PDE). A trend toward a higher mean PME/beta-NTP ratio was observed among high-grade lesions. Combined MR imaging and spectroscopy is a useful way to study tumor metabolism. Muscle contamination is a significant problem in analysis of the spectra. Better localization techniques are required.

Bone Neoplasms↗
PubMedDate not supplied

Magnetic resonance imaging of calcaneal aneurysmal bone cyst.

A 7-year-old black male presented with a lytic, expansile lesion of the calcaneus. This lesion was studied with conventional x-rays as well as MRI. The MR examination demonstrated a multiloculated lesion with material of a high- and low-signal intensity appreciated within each loculation. Pathologic review of the lesion demonstrated an aneurysmal bone cyst.

Bone Cysts↗