3D time-resolved contrast-enhanced MR DSA: advantages and tradeoffs.

The 3D TRICKS method for contrast-enhanced, time-resolved MR DSA has been recently described. In this paper, computer simulations are used to investigate the relative frame rate, temporal window, artery-vein temporal separation, contrast-to-noise ratio, and spatial resolution of TRICKS and conventional scans for breath-hold and non-breath-hold applications. For non-breath-hold applications, TRICKS can be configured to provide increased CNR or spatial resolution at an increased frame rate, but with a longer temporal window when compared with a series of conventional scans in which the central portion of k-space is sampled at the same rate as for the TRICKS scans. For breath-hold applications, TRICKS typically provides three images with 75% of the conventional single acquisition spatial resolution and is more tolerant of variations in contrast curve shape within the field of view.

Giant cell tumors of synovium (Pigmented villonodular synovitis) involving the vertebral column.

Giant cell tumors of synovium (pigmented villonodular synovitis) involving the vertebral column recently have been seen in two women: the third and fourth cases to be reported in the English-language literature. Unlike the previously reported cases, both these tumors grew outside the dura and produced symptoms of spinal cord compression. The first case involved lumbar vertebrae 5 and 6; the second, lumbar vertebrae 2 and 3. Even though initial resection of both tumors was incomplete, the patients improved postoperatively. One tumor was known to be unresectable at the time of surgery. In the other patient, a recurrence of symptoms required second and third resections 4 and 8 months after the first, respectively. Although synovial giant cell tumors rarely metastasize, the rate of local recurrence is high, especially if excision is incomplete. For this reason, close follow-up of patients with lesions in the spinal column is indicated. Increased physician awareness that synovial giant cell tumors can occur in the spine will help to ensure that these tumors are not misdiagnosed in this location.