Clinical experience in timed arterial compression contrast-enhanced magnetic resonance angiography of the hand.

PURPOSE: A retrospective analysis of the diagnostic performance of the timed arterial compression (TAC) technique, which allows freezing of the contrast bolus during first-pass contrast-enhanced (CE) magnetic resonance angiography (MRA) to diagnose vascular pathologies in the hand. MATERIAL AND METHODS: A total of 14 consecutive CE-MRAs of the hand were acquired by using the TAC technique. By inflating a blood pressure cuff up to 200 mm Hg triggered to the arterial contrast filling of the hand, prolonged measurement times up to 144 seconds, with a spatial resolution of 0.59 × 0.59 × 0.8 mm(3), could be realized. Overall image qualities, arterial signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and vessel conspicuity besides the final diagnosis were evaluated. RESULTS: All 14 TAC-CE-MRAs of the hand were successfully accomplished without any adverse events and yielded, in all cases, a final diagnosis with a high total number of vascular pathologies (57). High arterial SNR and CNR values exceeding the soil of 85 and 60, respectively, resulted. Thus, overall vessel visibility (>90%), vessel conspicuity (mean Δ signal intensity [SI]/mm = 1,193) and image quality on a per patient level (>60%) were rated as excellent or good. CONCLUSIONS: TAC-CE-MRA of the hand offers high diagnostic performance because of its increased spatial resolution while preserving contrast, which allowed detection of tiny stenoses of the digital arteries.

Improved vessel delineation in keyhole time-resolved contrast-enhanced MR angiography using a gadolinium doped flush.

PURPOSE: To prospectively assess the influence of a gadolinium doped saline flush compared with a pure saline flush on the image quality of the supra-aortic vessels using time-resolved contrast-enhanced MR angiography (4D CE-MRA) in a randomized double blind clinical trial. MATERIALS AND METHODS: Twenty-two patients scheduled for contrast-enhanced craniocerebral MRI underwent a supplemental 4D CE-MRA covering the carotids to the superior sinus consisting of 30 dynamics of a T1-weighted 3D gradient-echo sequence (FFE) in sagittal direction. The temporal resolution of 1.1 s per dataset was achieved using the keyhole technique with the reference scan acquired at the end. Immediately after the intravenous (IV) injection of 0.1 mmol Gd/kg body weight of gadoterate, our patients received a 50-mL flush consisting either of a 0.9% saline solution (n = 11) or doped with 50 mM gadolinium (n = 11; total Gd: 0.11 mmol/kg) at a flow-rate of 2 mL/s. Vessel delineation, image quality, signal-to-noise- (SNR) and contrast-to-noise (CNR) ratios over time were compared. RESULTS: Both vessel delineation (internal carotid artery [ICA]: slope(saline) = 308.5; slope(Gd) = 528.9; P = 0.006; superior sagittal sinus [SSS]: slope(saline) = 505.3; slope(Gd) = 674.9; P = 0.007) and CNR (ICA: CNR(saline) = 57.3; CNR(Gd) = 80.55; P = 0.0417; SSS: CNR(saline) = 74.15; CNR(Gd) = 117.4; P = 0.0331) of the ICA and SSS were significantly increased using the gadolinium doped flush. CONCLUSION: A low concentrated gadolinium flush in comparison to a pure saline flush improves significantly vessel contrast and their delineation in time-resolved CE-MRA using the keyhole technique.

Time-resolved, high-resolution contrast-enhanced MR angiography of dialysis shunts using the CENTRA keyhole technique with parallel imaging.

PURPOSE: To evaluate the use of a dynamic keyhole magnetic resonance angiography (MRA) sequence combined with sensitivity encoding (SENSE) for hemodialysis shunts, because surveillance with conventional contrast-enhanced MRA (CE-MRA) is limited by its low temporal resolution, resulting in arteriovenous overlay. MATERIALS AND METHODS: A total of 12 patients with Brescia-Cimino shunts were investigated prospectively using the new technique. During the contrast passage (gadoterate, Gd-DOTA) a series of five to nine dynamic central k-space measurements (10% for upper-arm shunt, 25% for lower-arm shunt) followed by a full reference data set were acquired. The outer k-space data of the single reference scan were used to complete the dynamic data sets. RESULTS: All studies were diagnostic (17 stenoses, three aneurysms) without complications. The acquisition times for a single dynamic scan of the upper- and lower-arm shunts were 2.2 and 3.2 seconds, respectively, while the reference scan needed 13 and 22.4 seconds, respectively. The dynamic angiograms allowed the differentiation of arterial and venous filling despite a mean peak delay time of only 4.2 seconds in the shoulder region. Image quality qualified in consensus by two experienced readers was rated "good" in 19 cases and "intermediate" in five cases with high mean values for signal-to-noise ratios (SNRs) and contrast-to-noise-ratios (CNRs). CONCLUSION: We have successfully implemented a fast, dynamic, CE-MRA technique with CE timing robust angiography (CENTRA) keyhole and SENSE in clinical routine. High spatial and temporal resolution improve the diagnostics of dialysis shunts and allow the assessment of detailed, dynamic, four-dimensional (4D) information.

Gradient-enhanced volume rendering: an image processing strategy to facilitate whole small bowel imaging with MRI.

MRI of the small bowel with positive contrast from orally administered contrast agent is a promising non-invasive imaging method. The aim of our study was to introduce small bowel MRI in a display format that clinicians are accustomed to and that maximizes the amount of information visualized on a single image. Twelve healthy volunteers, median age 32 years (range 18-49 years) participated in the study. A mixture of 20 ml Gd-DOTA (Dotarem), 0.8 g/kg body weight psyllium fibre (Metamucil) and 1.2 l water were sequentially administered over a period of 4 h. Imaging was performed on a 1.5 T unit (Philips Gyroscan, Intera). Fat-saturated, 3D, gradient echo imaging was performed while the patient was in apnea (30 s). Bowel motion was reduced with 40 mg intravenously administered scopolamine (Buscopan). A 3D, gradient-enhanced, volume rendering technique was applied to the 3D data sets. Standard projections [left anterior oblique (LAO), right anterior oblique (RAO), supine and prone] resembling conventional enteroclysis were successfully generated within fewer than 10 min processing time. Reconstructions were reproducible and provided an entire overview of the small bowel. In addition thin-slab volume rendering allowed an overlap-free display of individual structures. Positive contrast from orally administered contrast agent, combined with a gradient enhanced volume rendering method, allows the reconstruction of the small bowel in a pattern resembling conventional double-contrast enteroclysis. Segmental display without overlay is possible.

First report of an accessory popliteal muscle: detection with MRI.

During an MRI examination of the knee in a 48-year-old patient suffering from degenerative changes of a partly resected medial meniscus and concomitant osteoarthritis of the knee joint, an unusual variant of an accessory muscle in the popliteal fossa was found. To our best knowledge this muscle has never been described before. Because of the close relationship to the popliteal muscle with regard to course and localisation in the deep popliteal fossa ventral to the popliteal artery, the term "accessory popliteal muscle" is proposed.

Primary cerebral leiomyosarcoma in a child.

We present a 13-year-old boy with a low-grade primary intra-axial cerebral leiomyosarcoma. MRI showed a contrast-enhancing intra-axial mass with features of a cell-rich tumour. The diagnosis was established after neurosurgery and exclusion of an extracerebral primary tumour. The resection of local recurrence 6 months later confirmed the diagnosis, but a higher grade of malignancy was established. The patient died 15 months after the onset of symptoms from general intracranial and intraspinal spread.

Giant cardiac myxoma with malignant transformed glandular structures.

A case of a right-sided giant cardiac myxoma with malignant transformation of glandular structures causing systemic metastases is described. Plain chest radiography and computed tomography localized the tumor within the heart. Exact depiction of the origin of the tumor using subtracted 2D-projection MR angiography is documented. Radiologic findings and differential diagnosis of this unique tumor are discussed.

High-resolution magnetic resonance angiography of hands with timed arterial compression (tac-MRA).

Timed arterial compression (tac) of blood flow can be achieved by inflation of a blood-pressure cuff. We postulated that this technique might improve contrast-enhanced magnetic resonance angiography (MRA) of the arteries of the hands. We studied eight volunteers and six patients with occlusive arterial disease of the hands with standard MRA and tac-MRA. Compared with standard MRA, acquisition time was extended with the blood-pressure cuff by a factor of four, leading to quadrupled image resolution (512x1024). Furthermore, flow-related artifacts were not seen. Tac-MRA permits visualisation of the peripheral arterial system in finer detail than that achieved with standard MRA.