Anticholinergic agents result in weaker and shorter suppression of uterine contractility compared with intestinal motion: time course observation with cine MRI.

PURPOSE: To evaluate the time course effects of anticholinergic agents on uterine contractility and intestinal motion with cine magnetic resonance imaging (MRI). MATERIALS AND METHODS: Using a 1.5 T MRI scanner, 60 T2-weighted half-Fourier rapid acquisitions with relaxation enhancement images of the uterus were serially acquired over 3 minutes in 25 healthy women in the periovulatory phase, at four instances, prior to and 2-5, 5-8, and 10-13 minutes after intravenous injection of 20 mg of hyoscine butylbromide. Uterine peristalsis frequency (waves / 3 min) and degrees of endometrial transformation, subendometrial conduction, outer myometrial conduction, sporadic myometrial contraction, and intestinal movement were independently evaluated by three readers. RESULTS: Uterine peristalsis frequency of 6.14 ± 2.34 decreased the most at 2-5 minutes (P < 0.001) by 1.41 (95% confidential interval [CI] = 0.59-2.22), or 23.0% ([6.14-4.73]/6.14) and remained reduced at 5-8 minutes (P = 0.013) by 0.97 (95% CI = 0.15-1.78), or 15.8% ([6.14-5.17]/6.14) after injection. The degree of intestinal movement was 3.32 ± 0.54 and was prominently reduced at every phase (P < 0.001 for all) and maximally decreased to 0.67 ± 0.65 at 5-8 min. It increased to 1.36 ± 0.72 at 10-13 minutes compared with the degrees of motion at 2-5 minutes (P = 0.04) and 5-8 minutes (P = 0.004). CONCLUSION: Suppression of uterine peristalsis was weaker and shorter compared with the stronger and longer suppression of intestinal movement by the intravenous administration of anticholinergic agents.

Unenhanced MR portography with a half-Fourier fast spin-echo sequence and time-space labeling inversion pulses: preliminary results.

OBJECTIVE: For this study, we aimed to selectively visualize the intrahepatic portal veins using 3D half-Fourier fast spin-echo (FSE) MR angiography (MRA) with a time-space labeling inversion pulse (T-SLIP) and to optimize the acquisition protocol. SUBJECTS AND METHODS: Respiratory-triggered 3D half-Fourier FSE scans were obtained in 25 healthy adult subjects combined with two different T-SLIPs: one placed on the liver and the thorax to suppress signals of the liver parenchyma, hepatic veins, and abdominal arteries and the other on the lower abdomen to suppress the ascending signal of the inferior vena cava. One of the most important factors was the inversion time (TI) of the inversion pulse for the liver and thorax. Image quality was evaluated in terms of signal-to-noise ratio, contrast-to-noise ratio, and mean visualization scores at four different TIs: 800, 1,200, 1,600, and 2,000 milliseconds. RESULTS: Selective visualization of the portal vein was successfully achieved in all volunteers, and anatomic variations were also seen in three subjects. A TI of 1,200 milliseconds was optimal in our protocol because it was sufficient for peripheral portal vein visualization and was most suitable for signal suppression of the hepatic veins and liver parenchyma. CONCLUSION: Half-Fourier FSE scanning with T-SLIPs enabled selective visualization of the portal vein without an exogenous contrast agent.

Non-contrast-enhanced hepatic MR angiography: do two-dimensional parallel imaging and short tau inversion recovery methods shorten acquisition time without image quality deterioration?

OBJECTIVE: To study whether shortening the acquisition time for selective hepatic artery visualization is feasible without image quality deterioration by adopting two-dimensional (2D) parallel imaging (PI) and short tau inversion recovery (STIR) methods. MATERIALS AND METHODS: Twenty-four healthy volunteers were enrolled. 3D true steady-state free-precession imaging with a time spatial labeling inversion pulse was conducted using 1D or 2D-PI and fat suppression by chemical shift selective (CHESS) or STIR methods. Three groups of different scan conditions were assigned and compared: group A (1D-PI factor 2 and CHESS), group B (2D-PI factor 2×2 and CHESS), and group C (2D-PI factor 2×2 and STIR). The artery-to-liver contrast was quantified, and the quality of artery visualization and overall image quality were scored. RESULTS: The mean scan time was 9.5±1.0 min (mean±standard deviation), 5.9±0.8 min, and 5.8±0.5 min in groups A, B, and C, respectively, and was significantly shorter in groups B and C than in group A (P<0.01). The artery-to-liver contrast was significantly better in group C than in groups A and B (P<0.01). The scores for artery visualization and overall image quality were worse in group B than in groups A and C. The differences were statistically significant (P<0.05) regarding the arterial branches of segments 4 and 8. Between group A and group C, which had similar scores, there were no statistically significant differences. CONCLUSION: Shortening the acquisition time for selective hepatic artery visualization was feasible without deterioration of the image quality by the combination of 2D-PI and STIR methods. It will facilitate using non-contrast-enhanced MRA in clinical practice.

Visualization of external carotid artery and its branches: non-contrast-enhanced MR angiography using balanced steady-state free-precession sequence and a time-spatial labeling inversion pulse.

PURPOSE: To evaluate visibility of the external carotid artery (ECA) and its branches using three-dimensional (3D) balanced steady-state free-precession (SSFP) MR angiography with a time-spatial labeling inversion pulse (Time-SLIP), and to provide an optimal value of the inversion time (TI). MATERIALS AND METHODS: Peripheral-pulse-wave-gated 3D balanced SSFP images were obtained in 20 healthy volunteers. Images with a Time-SLIP using four different TIs (600, 900, 1200, and 1500 ms) and without a Time-SLIP, referred to as sequence A to E, were acquired for each subject and compared for visibility scores of ECA system and relative signal intensity (SI) of ECA. RESULTS: Average Friedman rank for overall visibility was 1.63, 3.01, 3.59, 3.58, and 3.20 for sequence A to E, respectively. Sequence C and D yielded significantly higher visibility than sequence A, B, and E. The mean relative SI value was 0.97, 0.87, 0.81, 0.76, and 0.67 for sequence A to E, respectively. CONCLUSION: Balanced SSFP MR angiography with a Time-SLIP is superior to that without a Time-SLIP, showing excellent visualization of ECA system in approximately 3 min in average with sufficient background suppression including veins and salivary ducts. A TI of 1200 ms was considered to be optimal for this purpose.

Visualization of the lenticulostriate artery with flow-sensitive black-blood acquisition in comparison with time-of-flight MR angiography.

PURPOSE: To evaluate the capability of flow-sensitive black blood (FSBB) acquisition to visualize the lenticulostriate artery (LSA) in comparison with time-of-flight (TOF) angiography. MATERIALS AND METHODS: Twenty-one healthy subjects (13 males and 8 females, 19-44 years old) were enrolled in this study after obtaining written informed consent. Magnetic resonance imaging (MRI) examinations were performed with FSBB and TOF to visualize the LSA using a 1.5T MRI unit. In FSBB acquisition a motion probing gradient of b = 4 sec/mm(2) was applied to dephase blood flow. Images were reconstructed into coronal sections and were evaluated in terms of number, length, and image quality at origins and distal areas of visualized LSA branches with a four-point scale. RESULTS: In all, 145 LSA branches were visualized with FSBB and 66 branches with TOF. There was no LSA visualized only with TOF. In all evaluated terms, FSBB was significantly better than TOF. CONCLUSION: We could better visualize the LSA with FSBB than with TOF, both quantitatively and qualitatively. FSBB is a promising method, although it remains to be evaluated in clinical cases.

Whole-heart coronary magnetic resonance angiography with parallel imaging: comparison of acceleration in one-dimension vs. two-dimensions.

PURPOSE: To evaluate visualization of the whole-heart coronary arteries accelerated with parallel imaging (PI) applied in two-dimension (2D) in comparison with one-dimension (1D). MATERIALS AND METHODS: Seventeen healthy subjects were studied with a 1.5-T scanner equipped with a whole body phased array coil system and 16-channel receivers. Using 16 coil elements, whole-heart coronary magnetic resonance angiography (CMRA) was acquired in two conditions of 1D-PI and 2D-PI. The former scan was accelerated in phase direction by factor of 2 and the latter in phase and slice directions by factors of 2.5 and 2, respectively. Visualized length of right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX) was measured. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) was also measured. The CMRA quality was assessed in segment-wise with a five-point scale. RESULTS: The average scan time decreased to 5.3+/-2.2 min in 2D-PI from 11.6+/-3.5 min in 1D-PI, reducing the scan time to 45%. The visualized length, SNR, and CNR in average were smaller for images of 2D-PI compared with those of 1D-PI, however, statistically significant results were observed only in RCA (P<0.05). Score reduction of 2D-PI image quality was limited to 0.34 in average, and only two out of fifteen segments (#2, 6) showed significant score deterioration (P<0.05). CONCLUSIONS: Compared with the relatively limited degree of image degradation, 2D-PI offered a large reduction of the acquisition time, which is of large benefit in clinical situations.

Non-contrast-enhanced MR angiography for selective visualization of the hepatic vein and inferior vena cava with true steady-state free-precession sequence and time-spatial labeling inversion pulses: preliminary results.

PURPOSE: To selectively visualize the hepatic vein and inferior vena cava (IVC) using three-dimensional (3D) true steady-state free-precession (SSFP) MR angiography with time-spatial labeling inversion pulse (T-SLIP), and to optimize the acquisition protocol. MATERIALS AND METHODS: Respiratory-gated 3D true SSFP scans were conducted in 23 subjects in combination with two different T-SLIPs (one placed in the thorax to suppress the arterial signal and the other in the abdomen to suppress the portal venous signal). One of the most important factors was the inversion time (TI) of abdominal T-SLIP, and the image quality was evaluated at four different TIs of 800, 1200, 1600, and 2000 msec in terms of relative signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and mean visualization scores. RESULTS: No significant difference was observed in SNR and CNR between each TI. However, IVC visualization scores were better at TIs of 1600 and 2000 msec, and overall image quality was better at TIs of 1200 and 1600 msec. Therefore, the TI of 1600 msec was considered to provide the optimal balance between IVC visualization and signal suppression of the portal vein in our protocol. CONCLUSION: True SSFP scan with T-SLIPs enabled selective visualization of the hepatic vein and IVC without an exogenous contrast agent.

Non-contrast-enhanced hepatic MR angiography with true steady-state free-precession and time spatial labeling inversion pulse: optimization of the technique and preliminary results.

OBJECTIVE: To selectively visualize the hepatic arteries using the respiratory-triggered three-dimensional (3D) true steady-state free-precession (SSFP) projection magnetic resonance angiographic sequence with time spatial labeling inversion pulse (T-SLIP), and describe the optimization of this protocol. MATERIALS AND METHODS: Twenty healthy volunteers were examined in this study. A respiratory-triggered 3D true SSFP combined with T-SLIP was performed. Among several key factors that affect the image quality, the most important is the inversion time (TI). Therefore, according to the difference in TI, four image groups: group A (TI of 800 ms), group B (TI of 1000 ms), group C (TI of 1200 ms), and group D (TI of 1400 ms), were assigned and compared to detect the optimal TI for hepatic artery visualization. For quantitative assessment, the relative signal intensity, i.e., Cv-l (vessel-to-liver contrast) of the right hepatic artery was measured. For qualitative evaluation, the quality of vessel visualization and the order of identified hepatic artery branches were evaluated by two radiologists. RESULTS: Selective and high-contrast visualization of the hepatic arteries was acquired in all cases. Regarding the quantitative assessment, Cv-l decreased in group D due to background signal recovery, but there was no significant difference between groups (p-value >0.05). Regarding the qualitative evaluation, there were significant differences between group A and the other groups (p-value <0.01) and between groups B and C (p-value <0.05). In group C, both the image quality score and mean value for the order of the hepatic artery branches were highest, and a TI of 1200 ms was thought to be optimal regarding the balance between vessel-to-liver contrast and peripheral hepatic artery visualization. CONCLUSION: The MR angiographic technique using true SSFP with T-SLIP enabled the selective visualization of hepatic arteries without the need for an exogenous contrast agent or breath-hold.

Facilitated acquisition of whole-heart coronary magnetic resonance angiography with visual feedback of respiration status.

Three dimensional (3D) whole-heart (WH) coronary MR angiography (CMRA) requires an extended imaging time, but it may be reduced by providing a subject with visual feedback (VFB). Thirteen healthy volunteers were scanned and quality of 3D WH-CMRA images was compared among three scan conditions: free breathing (FB) with and without VFB (FB + VFB and FB - VFB, respectively) and multiple breath-holds with VFB (MBH + VFB). All but two subjects were able to complete all scans. The average scan times were 10.0 +/- 2.2, 10.0 +/- 2.5, and 8.2 +/- 1.3 min for FB - VFB, FB + VFB, and MBH + VFB, respectively. In the MBH + VFB condition, scan time was significantly reduced by 18% compared with both FB scans. No significant difference in image quality was observed between the FB - VFB and MBH + VFB conditions, but scores were significantly deteriorated at some segments in the FB + VFB condition. The MBH + VFB scan can be performed with a shorter scan time without failure or impairment of image quality.

Non-contrast-enhanced MR portography with time-spatial labeling inversion pulses: comparison of imaging with three-dimensional half-fourier fast spin-echo and true steady-state free-precession sequences.

PURPOSE: To compare and evaluate images acquired with two different MR angiography (MRA) sequences, three-dimensional (3D) half-Fourier fast spin-echo (FSE) and 3D true steady-state free-precession (SSFP) combined with two time-spatial labeling inversion pulses (T-SLIPs), for selective and non-contrast-enhanced (non-CE) visualization of the portal vein. MATERIALS AND METHODS: Twenty healthy volunteers were examined using half-Fourier FSE and true SSFP sequences on a 1.5T MRI system with two T-SLIPs, one placed on the liver and thorax, and the other on the lower abdomen. For quantitative analysis, vessel-to-liver contrast (Cv-l) ratios of the main portal vein (MPV), right portal vein (RPV), and left portal vein (LPV) were measured. The quality of visualization was also evaluated. RESULTS: In both pulse sequences, selective visualization of the portal vein was successfully conducted in all 20 volunteers. Quantitative evaluation showed significantly better Cv-l at the RPVs and LPVs in half-Fourier FSE (P < 0.0001). At the MPV, Cv-l was better in true SSFP, but was not statistically different. Visualization scores were significantly better only at branches of segments four and eight for half-Fourier FSE (P = 0.001 and 0.03, respectively). CONCLUSION: Both 3D half-Fourier FSE and true SSFP scans with T-SLIPs enabled selective non-CE visualization of the portal vein. Half-Fourier FSE was considered appropriate for intrahepatic portal vein visualization, and true SSFP may be preferable when visualization of the MPV is required.