Use of gadolinium-enhanced, ultrafast, three-dimensional, spoiled gradient-echo magnetic resonance angiography in the preoperative evaluation of living renal allograft donors.

BACKGROUND: Renal allograft retrieval from live donors requires an accurate determination of kidney anatomy including the renal arterial supply. Traditionally, conventional angiography has served as the gold standard for obtaining this information. More recently, magnetic resonance angiography (MRA) has been compared with conventional angiography. Although MRA has been shown to be more cost effective and to have none of the co-morbidity associated with the angiographic process, it still has been perceived to be less accurate than angiography. METHODS: We compared images obtained using a relatively new technique of gadolinium-enhanced, ultrafast, three-dimensional, spoiled gradient-echo MRA with surgical findings in 15 living renal donors. In addition, average patient charge for MRA was compared with that of conventional angiogram. RESULTS: Fourteen patients were evaluated with the gadolinium-enhanced, ultrafast, three-dimensional, spoiled gradient-echo modality and the findings confirmed at surgery. On one occasion, a discrepancy occurred in which an accessory renal artery was suggested on the MRA but was not detected by conventional angiography. The accessory renal artery was later encountered at surgery. MRA was also used to evaluate patient 15 but was unsuccessful due to technical error. This patient was later found to have a positive cross-match with the recipient and therefore did not undergo surgery. CONCLUSIONS: We have found the gadolinium-enhanced MRA technique to be 100% accurate and as reliable as conventional angiography in determining renal vascular anatomy in living kidney donors. Additionally, it shares none of the associated potential angiographic complications and allows a 31% cost savings over angiography.

Magnetic resonance imaging and contrast CT of the lumbar spine. Comparison of diagnostic methods and correlation with surgical findings.

Thirty-two patients with suspected lumbar disc herniation were studied with magnetic resonance imaging (MRI) and contrast computed tomography (CT). One hundred disc levels were evaluated. Twenty-five patients underwent surgery on 31 discs, allowing anatomic confirmation of the diagnosis. Surgical findings supported the MRI diagnosis at 28 of 31 levels (90.3% accuracy), whereas the CT diagnosis correctly reflected only 24 of 31 levels (77.4% accuracy). Discrepancy between MRI and CT interpretation occurred at ten levels that were surgically explored. Computed tomography (CT) was incorrect at seven levels, and MRI was in error at three levels. The sensitivity of MRI was 91.7%, compared with 83.3% for CT, and the MRI specificity of 100% was superior to 71.4% for CT. This study demonstrates the clinical superiority of surface coil MRI over contrast CT in the evaluation of lumbar disc herniation. Surface coil MRI can be used as the initial diagnostic procedure for a suspected herniated lumbar disc, using invasive contrast studies and CT, if required, to clarify an equivocal MRI finding.

Hip pain in three children accompanied by transient abnormal findings on MR images.

In a study of three children experiencing hip pain, low-signal-intensity patterns in the femoral head on T1-weighted magnetic resonance (MR) images eventually resolved, reverting to the normal signal patterns. These findings occurred in conjunction with documented clinical improvement of the patients' condition. T2-weighted images revealed isointense signals initially at the abnormal sites. Isointense signals prevailed on follow-up T2-weighted images. These MR imaging findings are likely due to transient bone marrow edema. These findings support the apparent sensitivity of MR imaging in the evaluation of marrow-based pathologic processes. Some pediatric patients with hip pain may have signs of transient bone marrow edema, rather than avascular necrosis, on MR images. Conservative management should be considered in such cases.

The usefulness of computed tomography during and after radiation therapy in patients with brain tumors.

Two years of experience with 100 patients in the serial study of brain tumors during and after radiation therapy has shown that computed tomography is useful in (a) depiction of regression or growth of primary and metastatic intracranial tumors, (b) recognition of untoward sequelae of radiation therapy, such as necrosis and edema, and (c) appreciation of changes in tumor density and ventricular size. Representation cases are discussed and illustrated.

Positive and negative contrast myelography in spinal trauma.

The myelograms of 60 acutely injured patients were reviewed. Positive contrast material (Pantopaque) was preferred in cervical and thoracic trauma manifesting bony deformity, in cervical trauma without bony deformity (in the prone position), in delineating the thoracic spinal cord in the frontal projection, and in lumbar spinal injuries. Negative contrast material (air) was preferred in cervical trauma without bony deformity, to delineate the thoracic spinal cord in the lateral projection and in chronic trauma to demonstrate cord atrophy. An experimental, water-soluble positive contrast material (Amipaque) may show the spinal cord advantageously in both the anteroposterior and lateral projections and may be more extensively used. A protocol has been devised, based on the analysis of the myelographic findings.