Biomedical subjects

Romhild M Hoogeveen

Publications and source records attributed to Romhild M Hoogeveen.

6 recordsLinked to original sources

PubMed2006

Utilizing SENSE to reduce scan duration in high-resolution contrast-enhanced renal MR angiography.

PURPOSE: To evaluate the use of sensitivity encoding (SENSE) to reduce scan time and decrease detrimental artifacts arising from motion and bolus profile effects during contrast-enhanced MR angiography (CE-MRA) of the renal arteries (RAs). MATERIALS AND METHODS: A direct comparison of conventional and SENSE (acceleration factor 2) CE-MRA protocols was performed on 20 patients. Each patient underwent both scans. Both protocols achieved the same resolution, but the SENSE protocol was 50% faster and utilized a faster injection than the conventional scan. Three radiologists graded the images for image quality, artifact levels, and reader confidence. RESULTS: While the signal-to-noise ratio (SNR) decreased (26+/-5 vs. 30+/-10; P=0.04) with the SENSE protocol, the image-quality scores for four identified segments of the RAs increased or were unchanged. The largest improvements in image quality occurred in the more distal segments of the RAs. Parenchymal ringing (P=0.005) and RA blurring (P=0.006) were significantly reduced, and there was a trend toward improvement of RA ringing despite the increased injection rate. CONCLUSION: The faster SENSE scan maintained nearly the same SNR (due to faster injection of Gd-chelate), reduced artifact levels, and improved image quality ratings for the distal renal vessels.

Aged↗

PubMed2005

Contrast-enhanced peripheral MR angiography using SENSE in multiple stations: feasibility study.

PURPOSE: To investigate if the use of parallel imaging is feasible and beneficial for peripheral contrast-enhanced magnetic resonance angiography (CE-MRA). MATERIALS AND METHODS: A total of 19 consecutive patients underwent peripheral CE-MRA using SENSE with two-fold reduction in the upper and lower leg stations. Conventional nonaccelerated imaging using constant level appearance (CLEAR) was used in the aortoiliac station. The findings were compared with those in a similar patient group that underwent peripheral CE-MR angiography using our standard imaging protocol without SENSE. Intraarterial digital subtraction angiography (IA-DSA) was used as the standard of reference. Lower extremity vessels were divided into anatomic segments (aortoiliac, upper legs, lower legs) for review. In each anatomic segment signal- and contrast-to-noise ratios (SNR, CNR), venous contamination, subjective image quality, as well as sensitivity and specificity, were determined for both patient groups. RESULTS: SNR and CNR improved significantly for the aortoiliac and upper leg segments (all P-values < or = 0.001). Small reductions were seen in the frequency of disturbing venous enhancement (P = not significant). There were no significant differences with regards to subjective image quality or diagnostic accuracy (all P > 0.3). Overall sensitivity and specificity in the SENSE group were 81% and 95%, respectively. For the non-SENSE group, these values were 79% and 96%, respectively. CONCLUSION: Preliminary results show that three-station peripheral CE-MRA using a full length peripheral arterial coil in combination with SENSE in the upper and lower leg stations is feasible and useful for further optimization of peripheral MRA. Using SENSE allows for routine, high-quality depiction of the entire peripheral vascular tree including the pedal arch. Higher SENSE factors are needed for further optimization.

Aged↗

PubMed2004

High-spatial-resolution 3D balanced turbo field-echo technique for MR angiography of the renal arteries: initial experience.

PURPOSE: To compare a multislab balanced turbo field-echo magnetic resonance (MR) angiographic technique, without the use of a contrast agent, with digital subtraction angiography (DSA) for imaging of the renal arteries. MATERIALS AND METHODS: Twenty-five randomly selected patients (eight women and 17 men; age range, 27-88 years; mean age, 72 years) suspected of having renal artery stenosis underwent both DSA and balanced turbo field-echo MR angiography. A consensus result was obtained among three radiologists in evaluation of main renal arteries on balanced turbo field-echo images and DSA images. Sensitivity, specificity, and negative and positive predictive values of the balanced turbo field-echo technique were calculated, and receiver operating characteristic analysis was performed for depiction of hemodynamically significant stenosis. Cohen kappa analysis was used to assess agreement between the two imaging methods in grading of stenoses and depiction of significant stenosis. Accessory renal arteries also were evaluated. RESULTS: Fifty main renal arteries and 11 accessory arteries were fully depicted with DSA. DSA depicted 11 stenotic lesions in the main renal arteries. In comparison, balanced turbo field-echo MR angiography enabled visualization of 46 of 50 main renal arteries to their first branching points and depicted 10 of 11 accessory arteries. Sensitivity, specificity, negative predictive value, and positive predictive value of this technique for depiction of significant stenosis were 100% (four of four), 98% (41 of 42), 100% (41 of 41), and 80% (four of five), respectively. The area under the receiver operating characteristic curve was 0.988. kappa was 0.782 for grading of stenoses and 0.877 for depiction of significant stenosis. CONCLUSION: Multislab balanced turbo field-echo imaging has potential as an MR angiography technique for depiction of normal and diseased renal arteries.

Adult↗

PubMed2004

Parallel imaging in MR angiography.

The recently developed techniques of parallel imaging with phased array coils are rapidly becoming accepted for magnetic resonance angiography (MRA) applications. This article reviews the various current parallel imaging techniques and their application to MRA. The increased scan efficiency provided by parallel imaging allows increased temporal or spatial resolution, and reduction of artifacts in contrast-enhanced MRA (CE-MRA). Increased temporal resolution in CE-MRA can be used to reduce the need for bolus timing and to provide hemodynamic information helpful for diagnosis. In addition, increased spatial resolution (or volume coverage) can be acquired in a breathhold (eg, in renal CE-MRA), or in otherwise limited clinically acceptable scan durations. The increased scan efficiency provided by parallel imaging has been successfully applied to CE-MRA as well as other MRA techniques such as inflow and phase contrast imaging. The large signal-to-noise ratio available in many MRA techniques lends these acquisitions to increased scan efficiency through parallel imaging.

Contrast Media↗

PubMed2003

Implications of SENSE MR in routine clinical practice.

Sensitivity encoding (SENSE) uses multiple MRI receive coil elements to encode spatial information in addition to traditional gradient encoding. Requiring less gradient encodings translates into shorter scan times, which is extremely beneficial in many clinical applications. SENSE is available to routine diagnostic imaging for the past 2 years. This paper highlights the use of SENSE with scan time reduction factors up to 6 in contrast-enhanced MRA, routine abdominal imaging, mammography, cardiac and neuro imaging. It is shown that SENSE has opened new horizons in both routine and advanced MR imaging.

Contrast Media↗

PubMed2002

Utilizing SENSE to achieve lower station sub-millimeter isotropic resolution and minimal venous enhancement in peripheral MR angiography.

PURPOSE: To use the parallel imaging technique, sensitivity encoding (SENSE), to increase spatial resolution and decrease venous contamination in peripheral magnetic resonance angiography (MRA). MATERIALS AND METHODS: Moving table, single-bolus peripheral contrast-enhanced (CE) -MRA was performed on nine patients. Manual table movement combined with SENSE in the upper station allowed for more rapid overall scan coverage such that acquisition of the lower station began 34 seconds after aortic contrast arrival. True sub- millimeter isotropic resolution was achieved in the lower station. RESULTS: Diagnostic MR angiograms of all three stations were obtained in all nine patients. Venous enhancement did not confound interpretation in any case. Sub-millimeter lower station resolution provided excellent vascular detail. CONCLUSION: Decreased delay time between upper and lower station acquisition in single bolus peripheral MR angiograms, now possible using parallel imaging techniques, combined with lower station sub-millimeter resolution may decrease venous contamination and increase overall interpretability, thus increasing clinical acceptance of peripheral MRA.

Humans↗