The Effect of Respiration on the Contrast and Sharpness of Liver Lesions in MRI

Butts, Kim; Riederer, Stephen J.; Ehman, Richard L.

doi:10.1002/mrm.1910330102

Cited by 26 publications

(4 citation statements)

References 19 publications

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“…In recent years, there has been an ongoing effort to find a sensitive, efficient, and robust T2‐w sequence for liver imaging, because T2‐w sequences are indispensable for the detection and characterization of both focal and diffuse liver lesions (1–9). The most challenging problem is respiratory movement (10, 19), which limits a breath‐hold sequence to no longer than 20 to 25 seconds. One technique to overcome this problem is the SE technique with multiple averages, which is acquired in free breathing (1).…”

Section: Discussionmentioning

confidence: 99%

High‐resolution MR‐imaging of the liver with T2‐weighted sequences using integrated parallel imaging: Comparison of prospective motion correction and respiratory triggering

Zech¹,

Herrmann²,

Huber³

et al. 2004

Magnetic Resonance Imaging

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Purpose:To compare high-resolution T2-weigthed images of the liver with and without integrated parallel acquisition techniques (iPAT) using either breath-hold sequences in combination with prospective acquisition motion correction (PACE) or respiratory triggering. Materials and Methods:Ten volunteers and 10 patients underwent each four different high-resolution fast spin echo (FSE) T2-weigthed sequences with 5 mm slice thickness and a full 320 matrix: a multi-breath-hold FSE sequence with and without iPAT and PACE and a respiratory-triggered FSE sequence with and without iPAT. Image quality was rated with a five-point scale by two independent readers. Signal intensity measurements were performed on a water phantom. Results:The sequences with iPAT required a substantially shorter acquisition time without loss of image quality. Overall image quality was rated equal for all sequences by both readers. Image time for nine slices with iPAT was 13 seconds (19 seconds without iPAT) with multi-breath-hold and on average 4:00 minutes (7:02 minutes without iPAT) with respiratory triggering. Imaging with the PACE technique resulted in more correct positioning of the image stacks.Conclusion: T2-weighted fast imaging with iPAT is feasible and results in high-quality images within a short acquisition time. Overall image quality is not negatively affected by iPAT.

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Section: Discussionmentioning

confidence: 99%

High‐resolution MR‐imaging of the liver with T2‐weighted sequences using integrated parallel imaging: Comparison of prospective motion correction and respiratory triggering

Zech¹,

Herrmann²,

Huber³

et al. 2004

Magnetic Resonance Imaging

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“…In abdominal MR imaging fast T2-weighted sequences have improved the diagnostic sensitivity and specificity of lesion detection especially for liver imaging [20,21]. Also detection and characterization of different renal lesions have improved using T2-weighted TSE sequences [2,22].…”

Section: Imaging Analysismentioning

confidence: 99%

Fast sequences with fat suppression in breath-hold mode: new standard in contrast-enhanced T1-weighted MR imaging of renal tumors?

et al. 2001

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Our purpose was to analyze detection, diagnostic characterization, and staging of renal solid lesions using different fast T1-weighted sequences with fat suppression in breath-hold mode compared with a gradient-echo sequence after contrast application. Twenty-five patients with focal renal lesions were examined with a T1-weighted ultrafast turbo spin-echo (UTSE) sequence with frequency selective fat suppression (SPIR), two different segmented echo-planar imaging (EPI) sequences - a spin-echo and a gradient-echo echo-planar sequence (SE-, FFE-EPI) combined with SPIR and a gradient-echo (fast field echo, FFE) sequence in a prospective study. The images of all sequences were visually evaluated and in addition to qualitative evaluation the contrast-to-noise ratio (CNR) for cyst and solid lesions was measured. Among the different T1-weighted sequences, the best detection and characterization of renal solid lesions were obtained with the UTSE SPIR and the SE-EPI sequence (sensitivity: 100 and 75%, respectively; specificity: 90 and 75%, respectively). The FFE and FFE-EPI sequences showed lower sensitivity (86%) and the same specificity (75%). The staging of renal tumors was best achieved with the UTSE SPIR and SE-EPI sequence (84 and 73%, respectively). The staging was correct in only 47% and 58 for the FFE and FFE-EPI sequences, respectively. The investigated sequences showed no significant differences in CNR. The combination of fat suppression and breath-hold mode improves detection, characterization, and staging of renal lesions. The UTSE SPIR and SE-EPI sequence in breath-hold mode showed specific image artifacts, but offered high sensitivity and specificity for detection and characterization of renal lesions compared with the FFE sequence. The results of this study suggest, for T1-weighted imaging of renal tumors, use of UTSE or SE-EPI sequences with fat suppression in breath-hold mode for renal imaging.

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“…At the most basic level, filtering results in image blurring. This effect can be reduced by strategies such as reordering schemes (65–67) and inverse filtering (67) that minimize the effects of changes in relative contrast and tissue position occurring over the course of filling k‐space. These strategies are not always advisable though, since they may conflict with other imaging priorities.…”

Section: Effect Of Trajectory On Imagesmentioning

confidence: 99%

K‐space in the clinic

Paschal

Morris

2004

Magnetic Resonance Imaging

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Magnetic resonance imaging (MRI) sequences are characterized by both radio frequency (RF) pulses and time-varying gradient magnetic fields. The RF pulses manipulate the alignment of the resonant nuclei and thereby generate a measurable signal. The gradient fields spatially encode the signals so that those arising from one location in an excited slice of tissue may be distinguished from those arising in another location. These signals are collected and mapped into an array called k-space that represents the spatial frequency content of the imaged object. Spatial frequencies indicate how rapidly an image feature changes over a given distance. It is the action of the gradient fields that determines where in the k-space array each data point is located, with the order in which k-space points are acquired being described by the k-space trajectory. How signals are mapped into k-space determines much of the spatial, temporal, and contrast resolution of the resulting images and scan duration. The objective of this article is to provide an understanding of k-space as is needed to better understand basic research in MRI and to make well-informed decisions about clinical protocols. Four major classes of trajectories-echo planar imaging (EPI), standard (non-EPI) rectilinear, radial, and spiral-are explained. Parallel imaging techniques SMASH (simultaneous acquisition of spatial harmonics) and SENSE (sensitivity encoding) are also described.

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The Effect of Respiration on the Contrast and Sharpness of Liver Lesions in MRI

Cited by 26 publications

References 19 publications

High‐resolution MR‐imaging of the liver with T2‐weighted sequences using integrated parallel imaging: Comparison of prospective motion correction and respiratory triggering

High‐resolution MR‐imaging of the liver with T2‐weighted sequences using integrated parallel imaging: Comparison of prospective motion correction and respiratory triggering

Fast sequences with fat suppression in breath-hold mode: new standard in contrast-enhanced T1-weighted MR imaging of renal tumors?

K‐space in the clinic

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