High spatial-resolution CE-MRA of the carotid circulation with parallel imaging

Comparison of image quality between 2 different acceleration factors at 3.0 tesla

Kambiz Nael, Stefan G. Ruehm, Henrik J. Michaely, Whitney Pope, Gerhard Laub, J. Paul Finn, J. Pablo Villablanca

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

PURPOSE: We sought to evaluate and compare the image quality and vessel delineation of the carotid arteries with high spatial-resolution contrast-enhanced MRA (CE-MRA) at 3.0 T using integrated parallel acquisition (iPAT) with acceleration factors of 2 and 4. MATERIALS AND METHODS: Using an 8-channel neurovascular array coil, we performed prospective high-spatial resolution CE-MRA at 3.0 T of the head and neck on 24 patients (11 men, 13 women, ages 37-89) with suspected arterio-occlusive disease who were assigned randomly to 2 groups. Twelve patients (group A) were examined with a 3D-GRE sequence using iPAT with acceleration factor of 2. For the next 12 patients (group B) a near-identical sequence with an acceleration factor of 4 was applied. Higher iPAT factors were used to increase the spatial-resolution while keeping scan time unchanged. Two volunteers were scanned by both protocols. Phantom measurements were performed to assess the signal-to-noise ratio (SNR). The presence of artifact, noise, image quality of the arterial segments, and the presence and degree of arterial stenosis were evaluated independently by 2 radiologists. Statistical analysis of data was performed by using Wilcoxon rank sum test and 2-sample Student t test (P < 0.05 was indicative a statistically significant difference). The interobserver variability was tested by kappa coefficient. RESULTS: SNR values were significantly lower when iPAT with acceleration factor of 4 was used (P < 0.001). There was no significant difference between 2 groups in regards to image noise (P= 0.67) and artifact (P = 0.8). Both readers visualized the majority of carotid circulation with good image quality in both groups. For smaller intracranial arteries, such as the second-division of anterior and middle cerebral artery, anterior communicating artery, and superior cerebellar artery, the image quality and vessel delineation was significantly better at an iPAT factor of 4 (P < 0.01). The overall interobserver agreement for both the vessel depiction, and detection of arterial stenoses was higher in group B compared with group A. CONCLUSION: Use of parallel acquisition techniques with a high acceleration factor (iPAT-4) results in superior depiction of small intracranial arterial segments. Imaging at higher magnetic field strength, in addition to the use of an optimized 8-channel array coil, provides sufficient SNR to support faster parallel acquisition protocols, leading to improved spatial-resolution. More extensive clinical studies are warranted to establish the range of applications and confirm the accuracy of the technique.

Original languageEnglish (US)
Pages (from-to)391-399
Number of pages9
JournalInvestigative Radiology
Volume41
Issue number4
DOIs
StatePublished - Apr 2006
Externally publishedYes

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Signal-To-Noise Ratio
Arteries
Nonparametric Statistics
Artifacts
Pathologic Constriction
Anterior Cerebral Artery
Statistical Data Interpretation
Observer Variation
Middle Cerebral Artery
Magnetic Fields
Carotid Arteries
Noise
Volunteers
Neck
Head
Students

Keywords

  • Carotid MRA
  • Comparison study
  • High magnetic field or 3.0 Tesla
  • High-acceleration parallel acquisition techniques
  • Improved spatial-resolution for intracranial vasculature
  • MR angiography

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology

Cite this

High spatial-resolution CE-MRA of the carotid circulation with parallel imaging : Comparison of image quality between 2 different acceleration factors at 3.0 tesla. / Nael, Kambiz; Ruehm, Stefan G.; Michaely, Henrik J.; Pope, Whitney; Laub, Gerhard; Finn, J. Paul; Villablanca, J. Pablo.

In: Investigative Radiology, Vol. 41, No. 4, 04.2006, p. 391-399.

Research output: Contribution to journalArticle

Nael, Kambiz ; Ruehm, Stefan G. ; Michaely, Henrik J. ; Pope, Whitney ; Laub, Gerhard ; Finn, J. Paul ; Villablanca, J. Pablo. / High spatial-resolution CE-MRA of the carotid circulation with parallel imaging : Comparison of image quality between 2 different acceleration factors at 3.0 tesla. In: Investigative Radiology. 2006 ; Vol. 41, No. 4. pp. 391-399.
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T2 - Comparison of image quality between 2 different acceleration factors at 3.0 tesla

AU - Nael, Kambiz

AU - Ruehm, Stefan G.

AU - Michaely, Henrik J.

AU - Pope, Whitney

AU - Laub, Gerhard

AU - Finn, J. Paul

AU - Villablanca, J. Pablo

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N2 - PURPOSE: We sought to evaluate and compare the image quality and vessel delineation of the carotid arteries with high spatial-resolution contrast-enhanced MRA (CE-MRA) at 3.0 T using integrated parallel acquisition (iPAT) with acceleration factors of 2 and 4. MATERIALS AND METHODS: Using an 8-channel neurovascular array coil, we performed prospective high-spatial resolution CE-MRA at 3.0 T of the head and neck on 24 patients (11 men, 13 women, ages 37-89) with suspected arterio-occlusive disease who were assigned randomly to 2 groups. Twelve patients (group A) were examined with a 3D-GRE sequence using iPAT with acceleration factor of 2. For the next 12 patients (group B) a near-identical sequence with an acceleration factor of 4 was applied. Higher iPAT factors were used to increase the spatial-resolution while keeping scan time unchanged. Two volunteers were scanned by both protocols. Phantom measurements were performed to assess the signal-to-noise ratio (SNR). The presence of artifact, noise, image quality of the arterial segments, and the presence and degree of arterial stenosis were evaluated independently by 2 radiologists. Statistical analysis of data was performed by using Wilcoxon rank sum test and 2-sample Student t test (P < 0.05 was indicative a statistically significant difference). The interobserver variability was tested by kappa coefficient. RESULTS: SNR values were significantly lower when iPAT with acceleration factor of 4 was used (P < 0.001). There was no significant difference between 2 groups in regards to image noise (P= 0.67) and artifact (P = 0.8). Both readers visualized the majority of carotid circulation with good image quality in both groups. For smaller intracranial arteries, such as the second-division of anterior and middle cerebral artery, anterior communicating artery, and superior cerebellar artery, the image quality and vessel delineation was significantly better at an iPAT factor of 4 (P < 0.01). The overall interobserver agreement for both the vessel depiction, and detection of arterial stenoses was higher in group B compared with group A. CONCLUSION: Use of parallel acquisition techniques with a high acceleration factor (iPAT-4) results in superior depiction of small intracranial arterial segments. Imaging at higher magnetic field strength, in addition to the use of an optimized 8-channel array coil, provides sufficient SNR to support faster parallel acquisition protocols, leading to improved spatial-resolution. More extensive clinical studies are warranted to establish the range of applications and confirm the accuracy of the technique.

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KW - High-acceleration parallel acquisition techniques

KW - Improved spatial-resolution for intracranial vasculature

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