Breast MR imaging with commercially available techniques: radiologic-pathologic correlation.

PURPOSE: To evaluate the clinical utility of dynamic gadolinium-enhanced magnetic resonance (MR) imaging of the breast with commercially available techniques in patients scheduled for excisional biopsy. MATERIALS AND METHODS: A total of 91 breast abnormalities, 70 benign and 21 malignant, were evaluated. Thin-section three-dimensional gradient-echo images were obtained before and 2, 4, and 7 minutes after injection of contrast material. Three radiologists prospectively evaluated the mammograms and MR images. RESULTS: The areas under the receiver operating characteristic curves were 0.820 for mammography and 0.893 for MR imaging (P = .67). Sensitivity of MR imaging was 82.5%, compared with 74.6% for mammography. Specificity of MR imaging was 82.5%, compared with 79.1% for mammography. Enhancement profiles showed early intense enhancement in malignancies but considerable overlap with enhancement of benign disease. CONCLUSION: Breast MR imaging is a slightly more sensitive modality than mammography but not a highly specific technique for evaluating breast lesions. It has utility in several clinical situations but should not be used as a substitute for biopsy or general screening.

Preoperative diagnosis of an extradural cyst arising from a spinal facet joint: case report.

A case of a lumbar spinal extradural cyst is reported. An accurate preoperative diagnosis was made using magnetic resonance imaging. Characteristic findings on magnetic resonance imaging obviate the need for any additional radiological studies. The clinical features, radiological findings, and pathogenesis of these lesions are discussed.

MR characteristics of subdural hematomas and hygromas at 1.5 T.

MR images of 24 patients with 33 subdural collections were retrospectively reviewed to determine the spectrum of MR findings associated with such lesions. The lesions were dated by history, when available. Hematomas were grouped as follows: acute, four; early subacute, four; late subacute, four; chronic, 13. Six collections were classified as rehemorrhage; and two patients had CSF hygromas. Subdural hematomas evolved in a pattern similar to intracerebral hemorrhage with the exception of chronic subdural hematomas, in which isointensity of hypointensity relative to gray matter was observed on short TR/TE images compared with the persistent very high signal intensity noted in chronic parenchymal hematomas. Hemosiderin was rarely seen in chronic hematomas. These findings are most likely the result of the absence of a blood-brain barrier, which allowed clearance and dilution of blood products. Subdural hematomas with repeat hemorrhage demonstrated multiple phases of bleeding with layering phenomenon and more frequent hemosiderin deposition. It is possible that the clearance of blood products, as observed in chronic subdural hematomas, is impaired or poorly functional when rehemorrhage occurs. The persistence of high signal from methemoglobin in a hematoma that is expected to be in the chronic phase also suggests repeated hemorrhage. Acute CSF subdural hygromas had signal intensities identical to CSF without MR evidence of blood products. At surgery, clear fluid under pressure was found. MR imaging, with its unique ability to delineate the various phases of hemorrhage, is well suited to the evaluation of subdural hemorrhage.

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.

The tissue proton T1 and T2 response to gadolinium DTPA injection in rabbits. A potential renal contrast agent for NMR imaging.

Three different doses of gadolinium (Gd) DTPA were administered intravenously to rabbits. Cardiovascular responses and changes in blood T1 and T2 were serially followed for 15 minutes when the animals were sacrificed for in vitro measures of tissue T1 and T2. Gd-DTPA was distributed and excreted like water soluble iodinated contrast agents with large changes in blood, urine, and kidney proton relaxation. An imaging experiment confirmed the efficacy as an NMR contrast agent for renal excretion. At effective doses, no adverse effects were observed and the agent appeared to be much safer than x-ray contrast agents, but with a similar potential for clinical utility.