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Highest Resolution In Vivo Human Brain MRI Using Prospective Motion Correction.

Stucht D, Danishad KA, Schulze P, Godenschweger F, Zaitsev M, Speck O - PLoS ONE (2015)

Bottom Line: Even with a cooperative and trained subject, involuntary motion due to heartbeat, swallowing, respiration and changes in muscle tone can cause image artifacts that reduce the effective resolution.Prospective motion correction (PMC) at 3T and 7T has proven to increase image quality in case of subject motion.As a result, we present images among the highest, if not the highest resolution of in vivo human brain MRI ever acquired.

View Article: PubMed Central - PubMed

Affiliation: Biomedical Magnetic Resonance, Otto-von-Guericke University, Magdeburg, Germany; Institute of Biometry and Medical Informatics, Otto-von-Guericke University, Magdeburg, Germany.

ABSTRACT
High field MRI systems, such as 7 Tesla (T) scanners, can deliver higher signal to noise ratio (SNR) than lower field scanners and thus allow for the acquisition of data with higher spatial resolution, which is often demanded by users in the fields of clinical and neuroscientific imaging. However, high resolution scans may require long acquisition times, which in turn increase the discomfort for the subject and the risk of subject motion. Even with a cooperative and trained subject, involuntary motion due to heartbeat, swallowing, respiration and changes in muscle tone can cause image artifacts that reduce the effective resolution. In addition, scanning with higher resolution leads to increased sensitivity to even very small movements. Prospective motion correction (PMC) at 3T and 7T has proven to increase image quality in case of subject motion. Although the application of prospective motion correction is becoming more popular, previous articles focused on proof of concept studies and technical descriptions, whereas this paper briefly describes the technical aspects of the optical tracking system, marker fixation and cross calibration and focuses on the application of PMC to very high resolution imaging without intentional motion. In this study we acquired in vivo MR images at 7T using prospective motion correction during long acquisitions. As a result, we present images among the highest, if not the highest resolution of in vivo human brain MRI ever acquired.

No MeSH data available.


Related in: MedlinePlus

Dental brace and MPT marker.An individually manufactured dental brace (A) was worn by the subject during the measurement. A passive marker similar to the one shown in (B) was mounted on the brace’s extension reaching out of the helmet-design head coil. Planar grating patterns were printed on both sites of a transparent substrate forming moiré patterns. The retro reflective background of the marker ensured visibility to the camera and lighting unit (CLU) at low light exposure levels.
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pone.0133921.g001: Dental brace and MPT marker.An individually manufactured dental brace (A) was worn by the subject during the measurement. A passive marker similar to the one shown in (B) was mounted on the brace’s extension reaching out of the helmet-design head coil. Planar grating patterns were printed on both sites of a transparent substrate forming moiré patterns. The retro reflective background of the marker ensured visibility to the camera and lighting unit (CLU) at low light exposure levels.

Mentions: PMC was used in the acquisition of the images presented in this work. The subjects’ motion was optically tracked using a moiré phase tracking (MPT) system [37, 39]. This technology allows for high precision tracking of out-of-plane rotations, by deriving pose information from changes in a moiré pattern visible on a 15mm marker (Fig 1). Moreover, through photogrammetric techniques and image processing, the marker position could be tracked along six degrees of freedom. In previous studies [39] this system was described in detail and was used successfully to acquire motion corrected MRI images, particularly of intentionally moving subjects, at different field strengths with resolutions of up to 0.3 × 0.3 × 3 mm. In brief, the camera and lighting unit (CLU) of the MPT system consisted of a customized fixed focus, fixed aperture VGA camera (656 × 492 pixels) and LED flash illumination compatible with the high-field environment. The camera is mounted over the subject’s head inside the magnet bore using adhesive tape (Fig 2). Proper care was taken to make this mounting stable and vibration free. The photogrammetrically pre-calibrated camera [40] tracked the subject with 60 frames per second (fps) (maximum sampling rate is 85Hz).


Highest Resolution In Vivo Human Brain MRI Using Prospective Motion Correction.

Stucht D, Danishad KA, Schulze P, Godenschweger F, Zaitsev M, Speck O - PLoS ONE (2015)

Dental brace and MPT marker.An individually manufactured dental brace (A) was worn by the subject during the measurement. A passive marker similar to the one shown in (B) was mounted on the brace’s extension reaching out of the helmet-design head coil. Planar grating patterns were printed on both sites of a transparent substrate forming moiré patterns. The retro reflective background of the marker ensured visibility to the camera and lighting unit (CLU) at low light exposure levels.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4520483&req=5

pone.0133921.g001: Dental brace and MPT marker.An individually manufactured dental brace (A) was worn by the subject during the measurement. A passive marker similar to the one shown in (B) was mounted on the brace’s extension reaching out of the helmet-design head coil. Planar grating patterns were printed on both sites of a transparent substrate forming moiré patterns. The retro reflective background of the marker ensured visibility to the camera and lighting unit (CLU) at low light exposure levels.
Mentions: PMC was used in the acquisition of the images presented in this work. The subjects’ motion was optically tracked using a moiré phase tracking (MPT) system [37, 39]. This technology allows for high precision tracking of out-of-plane rotations, by deriving pose information from changes in a moiré pattern visible on a 15mm marker (Fig 1). Moreover, through photogrammetric techniques and image processing, the marker position could be tracked along six degrees of freedom. In previous studies [39] this system was described in detail and was used successfully to acquire motion corrected MRI images, particularly of intentionally moving subjects, at different field strengths with resolutions of up to 0.3 × 0.3 × 3 mm. In brief, the camera and lighting unit (CLU) of the MPT system consisted of a customized fixed focus, fixed aperture VGA camera (656 × 492 pixels) and LED flash illumination compatible with the high-field environment. The camera is mounted over the subject’s head inside the magnet bore using adhesive tape (Fig 2). Proper care was taken to make this mounting stable and vibration free. The photogrammetrically pre-calibrated camera [40] tracked the subject with 60 frames per second (fps) (maximum sampling rate is 85Hz).

Bottom Line: Even with a cooperative and trained subject, involuntary motion due to heartbeat, swallowing, respiration and changes in muscle tone can cause image artifacts that reduce the effective resolution.Prospective motion correction (PMC) at 3T and 7T has proven to increase image quality in case of subject motion.As a result, we present images among the highest, if not the highest resolution of in vivo human brain MRI ever acquired.

View Article: PubMed Central - PubMed

Affiliation: Biomedical Magnetic Resonance, Otto-von-Guericke University, Magdeburg, Germany; Institute of Biometry and Medical Informatics, Otto-von-Guericke University, Magdeburg, Germany.

ABSTRACT
High field MRI systems, such as 7 Tesla (T) scanners, can deliver higher signal to noise ratio (SNR) than lower field scanners and thus allow for the acquisition of data with higher spatial resolution, which is often demanded by users in the fields of clinical and neuroscientific imaging. However, high resolution scans may require long acquisition times, which in turn increase the discomfort for the subject and the risk of subject motion. Even with a cooperative and trained subject, involuntary motion due to heartbeat, swallowing, respiration and changes in muscle tone can cause image artifacts that reduce the effective resolution. In addition, scanning with higher resolution leads to increased sensitivity to even very small movements. Prospective motion correction (PMC) at 3T and 7T has proven to increase image quality in case of subject motion. Although the application of prospective motion correction is becoming more popular, previous articles focused on proof of concept studies and technical descriptions, whereas this paper briefly describes the technical aspects of the optical tracking system, marker fixation and cross calibration and focuses on the application of PMC to very high resolution imaging without intentional motion. In this study we acquired in vivo MR images at 7T using prospective motion correction during long acquisitions. As a result, we present images among the highest, if not the highest resolution of in vivo human brain MRI ever acquired.

No MeSH data available.


Related in: MedlinePlus