Although magnetic resonance (MR) images of the glenohumeral joint frequently demonstrate intraarticular fluid, no specific criteria have, to the authors' knowledge, been published that allow accurate assessment of the amount of fluid present. Also, despite the increasing use of MR arthrography of the shoulder, the optimal amount of intraarticular fluid that should be used with this technique has not been determined. The authors progressively distended the glenohumeral joint in six cadaveric shoulder specimens with a dilute gadopentetate dimeglumine solution and obtained MR images after injection of 2, 5, 10, 15, and 20 mL of the solution. The pattern of fluid distribution was evaluated, and these results were then used to estimate the amount of fluid that was present in the glenohumeral joint on MR images of 20 shoulders obtained in 12 asymptomatic volunteers. In 14 of these shoulders, intraarticular fluid was present; however, in none was more than 2 mL evident. Results of the cadaveric study also indicated that 15 mL of intraarticular fluid appears to be the optimal amount for MR arthrography.

Adult↗

PubMedDate not supplied

Radiologic search for embolized leaflets of prosthetic heart valves: a report of two cases.

In a radiologic search for embolized leaflets of Edwards-Duromedics bileaflet valves in 2 patients, the embolized fragments were localized in the iliac vessels using computed tomography. Sonography was successful in one case and standard X-ray films of the abdomen were negative in both cases. In vitro investigations with Björk-Shiley and Edwards-Duromedics leaflets suggested that standard X-ray films of the abdomen and pelvis should be considered as the first investigational technique. If negative, computed tomography of the lower abdomen should be done.

Adult↗

PubMedDate not supplied

Complement C2, C3, C4 and factor B allele distribution in the Gipsy population in Hungary.

Allotype frequencies of four complement proteins (C3, C2, factor B, and C4) were tested in 150 healthy Hungarian and 126 healthy Gipsy individuals living in Hungary. We observed significant differences between the two ethnic groups in the incidence of C3*F, Bf*F, C4A*Q0, C4A*3, C4B*1 and C4B*2 allotypes. Bf*F occurred more frequently among Gipsies, while frequencies for the other three allotypes was lower in this group than in Hungarians. The similarities in the allotype frequencies of C3 and Bf among Gipsy and Gaddis (India) populations supports the Indian origin of the former ethnic group.

Adult↗

PubMedDate not supplied

Induction of heme oxygenase-1 in the donor reduces graft immunogenicity.

There is increasing evidence that the induction of the enzyme heme oxygenase-1 (HO-1) improves both graft function and survival. Although it has been shown that HO-1 promotes graft protection, it remains unknown whether it reduces graft immunogenicity by modulating dendritic cells. In the current experiment, we investigated the impact of HO-1 induction on frequencies and trafficking of donor-derived dendritic cells (DCs). Kidneys from DA rats were transplanted into untreated Lewis recipients. Donor animals were treated with cobalt protoporphyrin (CoPP; 5 mg/kg IP) 24 hours prior to organ harvesting to induce HO-1. Controls remained untreated or received zinc protoporphyrin (ZnPP; 20 mg/kg, IP) to block HO-1 induction. Analyses of grafts, spleens, lymph nodes and blood of Lewis recipients were performed at days 1 and 3 posttransplantation. Donor-specific DCs were determined by flow cytometry using haplotype-specific mAb against RT1(ab) and mAb against OX62(+) antigens. Cell markers (CD4/CD8(+) T cells, ED1(+) monocytes, MHC class II(+) CD86(+) DC) were measured by immunohistochemical staining. T-cell alloreactivity of recipient splenocytes was measured by ELISPOT. Induction of HO-1 reduced frequencies of donor-derived DCs in the graft and recipient compartments, which was associated with reduced frequencies of CD4(+) T cells and CD8(+) T cells and alloreactivity. Expression of costimulatory molecule CD86 and MHC class II antigens were also reduced, although not significantly. Thus, induction of HO-1 reduced graft immunogenicity. These mechanisms may explain the protective effects of HO-1 induction.

Animals↗

PubMedDate not supplied

Orientation-selective aVLSI spiking neurons.

We describe a programmable multi-chip VLSI neuronal system that can be used for exploring spike-based information processing models. The system consists of a silicon retina, a PIC microcontroller, and a transceiver chip whose integrate-and-fire neurons are connected in a soft winner-take-all architecture. The circuit on this multi-neuron chip approximates a cortical microcircuit. The neurons can be configured for different computational properties by the virtual connections of a selected set of pixels on the silicon retina. The virtual wiring between the different chips is effected by an event-driven communication protocol that uses asynchronous digital pulses, similar to spikes in a neuronal system. We used the multi-chip spike-based system to synthesize orientation-tuned neurons using both a feedforward model and a feedback model. The performance of our analog hardware spiking model matched the experimental observations and digital simulations of continuous-valued neurons. The multi-chip VLSI system has advantages over computer neuronal models in that it is real-time, and the computational time does not scale with the size of the neuronal network.

Action Potentials↗

PubMedDate not supplied

Embolization of bone metastases.

PURPOSE: To assess the effectiveness and clinical usefulness of transcatheter embolization of bone metastases. PATIENTS AND METHODS: The procedures and outcome of 61 transcatheter embolization procedures performed in 51 patients with hypervascular skeletal metastases were retrospectively evaluated. Results from computed tomography, magnetic resonance imaging, and diagnostic angiography, performed before and after embolization, were reviewed. RESULTS: All embolizations were technically and clinically successful. Major blood loss during surgery was prevented in 32 cases; the size of viable tumor tissue in large, unresectable bone metastases was reduced before radiation or chemotherapy in 17 cases; and otherwise untreatable skeletal pain was decreased in 11 cases. Heavy bleeding from a metastasis was controlled in one case. The complications were temporary paresis of a lower extremity in three patients, cardiac arrest in one patients, and unintentional embolization of synthetic tissue adhesive in one patient. Median survival time was 28 months (range, 3-59 months). CONCLUSION: Transcatheter embolization is effective and reliable in the treatment of bone metastases.

Bone Neoplasms↗

PubMedDate not supplied

[Current aspects in the diagnosis of spondylodiscitis].

New aspects regarding the diagnosis of spondylodiscitis are shown by means of the casuistics of a severe immobilizing lumbar syndrome. In this special case only the MR-examination was able to make clear the diagnosis, at a time when all other diagnostic methods failed. The MR-examination was taken as primary and progressive diagnostic method and it also decided about therapeutic consequences.

Adult↗

PubMedDate not supplied

MRI in the diagnosis of primary lymphoma of bone: correlation with histopathology.

Seven patients with primary non-Hodgkin lymphoma of the skeleton were examined with MRI. The results were compared to "small cell" primary malignant bone tumors. The latter showed marked hyperintensity on SE T2-weighted images; in contrast, the lymphomas appeared as inhomogeneous lesions of low signal intensity on T2-weighted images. Histologic examination with silver stains of specimens of these lesions revealed a high content of fibrous tissue, which could explain the signal behavior on MR. All seven lymphomas were located in the epiphysis or metaphysis of the appendicular skeleton; intraarticular tumor growth was demonstrated in five cases.

Adolescent↗

PubMedDate not supplied

MR contrast arthrography (MRA) in osteochondrosis dissecans.

Osteochondrosis dissecans (OCD) is a lesion that characteristically affects the articular cartilage and subchondral bone with the potential of fragmentation and separation. Exact assessment of cartilaginous and subchondral bony changes is mandatory for the planning of adequate treatment. Therefore, we examined 25 knees using spin echo (SE) and gradient echo (GE) sequences on a 1.5 T superconducting unit prior to and following intraarticular administration of 40 ml of a 2 mmol/L Gd-DTPA solution (MR arthrography). For evaluation (staging) a modified Clanton and DeLee scheme was employed. Verification by arthroscopy or arthrotomy was available in 24 cases. A correct diagnosis of OCD with regard to its type prior to intraarticular injection of Gd-DTPA was possible in 39.3% using T1-weighted SE sequences and in 57.4% on GE sequences. After intraarticular administration of Gd-DTPA, the rate of correct diagnoses improved to 92.9% on T1-weighted SE sequences and 100% on GE sequences. Magnetic resonance arthrography appears to be helpful for the exact assessment of the articular cartilage overlying OCD lesions as well as for the differentiation between partial and complete separation of cartilaginous or osteocartilaginous fragmentations.

Adolescent↗

PubMedDate not supplied

Bone marrow edema of the hip: MR findings after core decompression.

Magnetic resonance imaging is an extremely sensitive technique for evaluation of bone marrow changes at an early stage of avascular necrosis (AVN) of the hip. We therefore examined 11 painful hips whose clinical symptoms led us to suspect idiopathic AVN. The radiographs of all of these either were normal or demonstrated a minimal decrease in radiodensity. Magnetic resonance demonstrated diffuse signal loss of the bone marrow at short TR/TE images of the femoral head in all hips, with various extensions in the head, neck, and intertrochanteric area. These regions turned iso- to hyperintense on long TR/TE images compatible with bone marrow edema (BME). Focal abnormalities characteristic for AVN were not seen in any of the cases. Radionuclide studies performed in six cases were positive. All patients underwent core decompression treatment. Hydrostatic bone marrow pressure measurement and intraosseous venography were positive in five cases when measured. Histology available in eight cases confirmed the presence of BME. Furthermore, the bone changes corresponded to those of early AVN. Follow-up examinations after core decompression with MR showed normal signal intensity in all cases. Magnetic resonance represents a viable diagnostic tool for BME and can monitor the therapeutic success of core decompression. Whether BME of the femoral head constitutes a distinct transient syndrome or represents an early form of AVN is controversial at present. Our findings support those who believe that BME may represent an initial stage of idiopathic AVN.

Adult↗

PubMedDate not supplied

Gerstmann-Sträussler-Scheinker syndrome: MR findings.

Explore the source record for details and available documents.

Adult↗

PubMedDate not supplied

CT and MR accuracy in the detection of tumor recurrence in patients treated for ovarian cancer.

OBJECTIVE: The aim of this prospective study was to evaluate the accuracy of clinical examinations (palpation/determination of serum tumor-associated antigen CA125 level), CT, and MRI in the detection of tumor recurrence in patients with treated ovarian cancer. MATERIALS AND METHODS: Twenty-four patients who had been treated for ovarian carcinoma were prospectively examined by clinical means (palpation/serum tumor-associated antigen CA125 level), CT, and MRI to assess their accuracy in detecting recurrent disease; results were correlated with surgical/bioptic/pathoanatomic findings. Nine patients had relapse; 15 women were disease-free. RESULTS: Examinations were true-negative in 14 patients (on palpation/CA125, CT, and MRI) and true-positive in 9 on palpation/CA125, in 6 on CT, and in 7 patients on MRI. False-positive examinations occurred in one patient on palpation/CA125, CT, and MRI and false-negative in zero on palpation/CA125, in three on CT, and in two on MRI, a sensitivity of 100% for palpation/CA125, 66.6% for CT, and 77.7% for MRI and a specificity of 93.3% for palpation/CA125, CT, and MRI. Accuracy of palpation/CA125 examinations was 95.8% in comparison with 83.3% for CT and 87.5% for MRI. CONCLUSION: Our results suggest that in the follow-up of ovarian cancer patients, assessment of serum tumor-associated antigen CA125 level is accurate in the determination of patients with tumor recurrence. Computed tomography is the primary imaging modality to prove macroscopic disease recurrence and can spare these patients from invasive restaging second-look laparotomy; MRI should be performed in women with questionable macroscopic recurrent tumor and negative CT examination. Neither CT nor MRI can confidently exclude microscopic disease.

Antigens, Tumor-Associated, Carbohydrate↗

PubMedDate not supplied

MR appearance of idiopathic synovial osteochondromatosis.

OBJECTIVE: A retrospective review of the MR examinations in 21 patients with idiopathic synovial osteochondromatosis (ISO) was performed to determine its MRI characteristics. MATERIALS AND METHODS: Twenty-one patients diagnosed with ISO had undergone MRI prior to surgery. The MR images were retrospectively evaluated for configuration and extent of lesion as well as for signal characteristics. RESULTS: Three distinct MR patterns were seen in ISO: A--lobulated homogeneous intraarticular signal isointense to slightly hyperintense to muscle on T1-weighted images and hyperintense on T2-weighted images (n = 3); B--pattern A plus foci of signal void on all pulse sequences (n = 17); and C--features of pattern A and B plus foci of peripheral low signal surrounding central fat-like signal (n = 2). The foci of signal void in pattern B and C corresponded to areas of calcification and the foci of peripheral low signal surrounding central fat-like signal in pattern C corresponded to areas of ossification. CONCLUSION: The MR appearance of ISO appears sufficiently unique to allow its differentiation from other causes of intraarticular pathology.

Adolescent↗

PubMedDate not supplied

Postcontrast MR arthrography in assessment of cartilage lesions.

OBJECTIVE: Although MR has been proven effective in evaluating many components of the musculoskeletal system, including ligaments, fibrocartilage, muscle, and bone marrow, its role in the evaluation of articular cartilage remains controversial. Recent studies have demonstrated that intraarticular injection of Gd-DTPA [MR arthrography (MRA)] improves the detection of cartilage abnormalities in cadaveric specimens. The aim of this study was to determine the efficacy of MRA for the detection of naturally occurring cartilage lesions in a clinical population. MATERIALS AND METHODS: Sixty knees of 58 patients were studied with a three-dimensional (3D) T2*-weighted GE sequence (FISP) both before and after and a T1-weighted (T1W) SE sequence after the intraarticular injection of a 2 mmol/L Gd-DTPA solution. All knees subsequently underwent arthroscopy or arthrotomy. RESULTS: The MRA sequences performed significantly better (kappa = 0.85) than the routine FISP sequences (kappa = 0.39) in both the detection and the staging of cartilage abnormalities. The MRA FISP sequence (kappa = 0.91) performed slightly better than the MRA T1W sequence (kappa = 0.85), but there was no statistically significant difference between the two sequences. No complications from the intraarticular injection of contrast material occurred. CONCLUSION: Therefore, MRA appears to be an effective and safe method for the evaluation of articular cartilage abnormalities.

Adolescent↗