Utility of simultaneously acquired gradient-echo and spin-echo cerebral blood volume and morphology maps in brain tumor patients.

An interleaved gradient-echo (GE) / spin-echo (SE) EPI sequence was used to acquire images during the first pass of a susceptibility contrast agent, in patients with brain tumors. Maps of 1) GE (total) rCBV (relative cerebral blood volume), 2) SE (microvascular) rCBV, both corrected for T(1) leakage effects, and 3) (DeltaR(2)*/DeltaR(2)), a potential marker of averaged vessel diameter, were determined. Both GE rCBV and DeltaR(2)*/DeltaR(2) correlated strongly with tumor grade (P = 0.01, P = 0.01, n = 15), while SE rCBV did not (P = 0.24, n = 15). When the GE rCBV data were not corrected for leakage effects, the correlation with tumor grade was no longer significant (P = 0.09, n = 15). These findings suggest that MRI measurements of total blood volume fraction (corrected for agent extravasation) and DeltaR(2)*/DeltaR(2), as opposed to maps of microvascular volume, may prove to be the most appropriate markers for the evaluation of tumor angiogenesis (the induction of new blood vessels) and antiangiogenic therapies. Magn Reson Med 43:845-853, 2000.

Measuring diffusion of solutes into intervertebral disks with MR imaging and paramagnetic contrast medium.

BACKGROUND AND PURPOSE: Experimental studies have shown that solutes diffuse more slowly into degenerated intervertebral disks than into normal disks. A noninvasive clinical study of diffusion in intervertebral disks is not generally available. Our purpose was to evaluate contrast-enhanced MR images to study diffusion in normal and degenerated lumbar intervertebral disks. METHODS: The change in signal intensity (as a proportion of baseline signal intensity) was calculated in lumbar intervertebral disks on MR images obtained before and after injection of intravenous contrast medium in 15 patients with low back pain. The intervertebral disks were classified as normal or degenerated on the basis of the MR appearance. Postoperative disks and degenerative intervertebral disks with a "high-intensity zone" were excluded. The changes in signal intensity as a proportion of baseline signal intensity were compared in degenerated disks and normal disks and the differences tested for statistical significance. RESULTS: After intravenous administration of a gadolinium complex, signal intensity in normal intervertebral disks increased an average of 36% of baseline. In intervertebral disks with signs of degeneration, it increased an average of 21% of baseline. The difference was significant. CONCLUSION: The study shows that diffusion into normal human lumbar intervertebral disks can be evaluated with MR imaging combined with intravenous contrast medium. With suitable MR techniques, the relationship between diffusion and disk degeneration, and the effect of trauma, drugs, and nutrition on disk degeneration can be studied noninvasively.

Diffusion into human intervertebral disks studied with MR and gadoteridol.

PURPOSE: To determine the feasibility of measuring diffusion into human intervertebral disks by means of MR imaging with an intravenous nonionic gadolinium complex (gadoteridol). METHODS: In 18 patients undergoing lumbar spine MR imaging, signal intensity was measured in the intervertebral disks after a dose of 0.1 mmol/kg and after a supplemental dose of 0.2 mmol/kg. RESULTS: Signal intensity in the intervertebral disks increased with both gadoteridol doses. A greater increase was consistently achieved with the 0.3 mmol/kg (total) dose than with the 0.1 mmol/kg dose. The increase was greater near the endplates than in the midportion of the disk. CONCLUSION: Diffusion into human intervertebral disks can be detected with MR imaging after intravenous administration of gadoteridol. MR imaging with a paramagnetic contrast medium can be used to study diffusion into disk cartilage in vivo and noninvasively.