Influence of magnetic field strength on T2* decay and phase effects in gradient echo MRI of vertebral bone marrow.

OBJECTIVE: The goal of this study was twofold: first, to quantify the influence of magnetic field strength (B0) on T2* and T2susceptibility relaxation rates in vertebral bone marrow; and second, to determine the significance of in-phase/out-of-phase phenomena in GE MRI as a function of TEs at different B0 values. MATERIALS AND METHODS: Magnetic resonance imaging of the spine was performed at 1.5, 1.0, and 0.2 T using a GE sequence (2D-FLASH) with variable TE. Vertebral body signal intensities were measured and plotted against TE values. These curves were used to calculate T2* decay of bone marrow at different B0 values. RESULTS: At all field strengths, we observed exponential signal decay, modulated by a cosine function, the periodicity of which was proportional to B0. The T2* values of vertebral bodies were 9.7 +/- 1.8 ms at 1.5 T, 17.2 +/- 2.4 ms at 1.0 T, and 53 +/- 5 ms at 0.2 T. True T2 relaxation time (independent of field strength) was 62 +/- 4 ms. The T2susceptibility was 11.7 ms at 1.5 T, 24.8 ms at 1.0 T, and 585 ms at 0.2 T. CONCLUSION: We conclude that at low B0, susceptibility effects become less important and T2* approaches true T2 relaxation.

Low-field versus high-field MR imaging of the knee: a comparison of signal behaviour and diagnostic performance.

A prospective study was undertaken to compare MR imaging of the knee obtained with low-field and high-field systems. In 10 subjects, MR imaging of the knee was performed on a 0.2 T permanent magnet and on a 1.5 T superconductive system. Similar spin echo (SE) and 3D-FISP (3D Fourier transform with steady state precession) acquisitions were obtained. Comparative image analysis was performed independently by four radiologists. Results show that the image quality and diagnostic performance delivered by state-of-the-art 0.2 T and 1.5 T systems is equivalent. Advantages of the 1.5 T system included: better signal-to-noise ratio, shorter scan times, better visualization of asymptomatic grade 1 meniscal degeneration on SE images. Advantages of 0.2 T images were: decreased chemical shift, susceptibility and flow artifacts, improved evaluation of subchondral bone on 3D-FISP images, slightly better patient tolerance. We conclude that, for MR imaging of the knee, a low-field system is a cost-effective alternative to more expensive superconducting units.

Reversed calcaneal spurs in children.

A study of the radiographs of 18 heels in children provided additional information about the developmental variant of reversed calcaneal spurs in young patients. The variant is seen in both boys and girls. Observations are made about the incidence of this radiological appearance.

The contused kidney, an angiographic picture.

Problems in the interpretation of an angiogram of a contused kidney are reported. The angiogram showed signs of avascularity and tumor vessels and a malignancy was considered. However, on operation the kidney appeared to be contused but otherwise normal. One should be aware of the possibility of pitfalls arising in early angiograms of contused kidneys.

Fibromuscular dysplasia as a cause of acute infantile hemiplegia.

A case of acute infantile hemiplegia, probably in co-occurrence with intracranial fibromuscular dysplasia, is reported. A review of the literature is given and some remarks are made concerning the management of this disease.

A Brodie's abscess caused by Salmonella give.

This report describes a typical Brodie's abscess caused by a Salmonella subspecies in an otherwise healthy individual. The rarity of the causative agent of this infection is stressed.

CT manifestations of intracranial involvement by Hodgkin's disease.

CT brain scanning, in a patient diagnosed as having stage IV B nodular sclerosis Hodgkin's disease and since 1978 in complete remission, demonstrated intracranial relapse. Neurological symptoms could be caused by scattered intracranial lesions from Hodgkin's disease. Different CT scan manifestations are described.

New findings in a patient with I-cell disease.

A case of I-cell disease showing some previously undescribed features is reported. The diagnosis was confirmed on the basis of lysosomal enzyme activity. The radiogram showed metaphyseal radiolucent bands not yet described and extensive epiphyseal stippling. The electronmicroscopical findings clearly demonstrated the presence of abnormal inclusion bodies in absorptive cells and in cells of the lamina propria of the small intestine. Immunological investigation revealed and increased absolute number of both B and T lymphocytes. The B cells, unlike the T cells, showed cytoplasmic vacuoles on phase contrast microscopy. The immune response to antigenic challenge was impaired, as assessed by specific antibody production and in vitro lymphocyte transformation testing.

Radiological findings in a case of type II fucosidosis. A case report.

This paper describes radiological characteristics of the skeleton in a patient suffering from type II fucosidosis. The early symptom of anterior beaking of the vertebral bodies, in combination with mental retardation and angiokeratoma corporis diffusum, can suggest the possibility of type II fucosidosis.