ADVANCED CLINICAL BRAIN IMAGING AT 3 T ADVANCED CLINICAL BRAIN IMAGING AT 3 T SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design Val M. Runge Scott and White Clinic and Hospital Bodie J. Correll Texas A&M University Health Science Center Ervin L. Lowther Texas A&M University Health Science Center Frederik L. Giesel German Cancer Research Center (DKFZ) Val M. Runge Scott and White Clinic and Hospital Bodie J. Correll Texas A&M University Health Science Center Ervin L. Lowther Texas A&M University Health Science Center Frederik L. Giesel German Cancer Research Center (DKFZ) TITLE/AUTHORS

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design ABSTRACT BACKGROUND INFORMATION - Advanced head coil design with 3 T imaging substantially improves the available signal-to-noise ratio (SNR), making possible a significant reduction in scan time, the use of advanced parallel imaging, high spatial resolution imaging (reduced voxel size in 3D acquisitions, whether for imaging of the brain itself or the vasculature) and implementation of innovative imaging techniques. The use of higher parallel imaging factors in conventional diffusion-weighted echoplanar imaging (EPI), together with the implementation of a fast spin echo (FSE) based BLADE diffusion-weighted scan is illustrated in patients with acute infarction (the latter free of bulk susceptibility artifact and geometric image distortion).

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design ABSTRACT continued With T1-weighted imaging, the 32 channel coil design permits a factor of two reduction in scan time for 2D imaging, and enables the use of a T1- weighted turboFLASH BLADE technique for motion robust imaging and alternatively an ultra-high resolution 3D T1-weighted FLASH scan for more cooperative patients.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design OBJECTIVE The main objective of this exhibit is to demonstrate the potential for improved clinical brain imaging at 3 T, afforded by the available increased SNR due to the use of a FDA approved, commercially available, 32 channel coil, focusing on: (1) decreased scan time, (2) utilization of new advanced imaging sequences, and (3) increased spatial resolution.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design ORGANIZATION Applications employing the improved SNR and parallel imaging capability are illustrated in patient exams at 3 T using: > FSE BLADE DWI > 2D T1-weighted FLASH > T1-weighted turboFLASH BLADE > FLAIR and T2-weighted BLADE > SPACE

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design Acknowledgment: The BLADE pulse sequences and associated image reconstruction software were developed by Alto Stemmer from Siemens Medical Solutions. TEACHING POINTS > To illustrate the potential of new advanced imaging sequences, utilizing the SNR and parallel imaging capability of the 32 channel coil, including a T1-weighted BLADE turboFLASH technique for reduced motion artifacts and a diffusion weighted BLADE FSE sequence for reduction of bulk susceptibility artifacts > To review the use of BLADE (PROPELLER) in combination with the 32 channel coil, illustrating the decrease in scan time that can be achieved (to 2:06 min:sec for 4 mm sections with FLAIR BLADE and 0:56 with T2 BLADE), and the resultant image quality

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design INTRODUCTION Utilizing multiple institutional review board (IRB) approved protocols, a 32-channel head coil (32-element design with 32 integrated preamplifiers, now FDA approved) was evaluated on a Tim Trio 3 T MR system (Siemens Medical Solutions) in 46 normal volunteers (60 separate MR sessions) and 30 patients. In regard to the latter, the diagnostic exam required by the IRB for clinical purposes was first acquired using the standard 12-channel head coil (Head Matrix Coil - 12-element design with 12 integrated preamplifiers, one ring of 12 elements each), and then imaging was performed with the 32-channel head coil. The performance of the 32-channel coil in contrast enhanced MRA using TWIST in combination with low dose gadolinium chelate injection was also evaluated.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FSE BLADE DWI Twenty-two normal volunteers and five patients, the latter with acute to early subacute ischemic infarcts, were studied with diffusion weighted imaging (DWI), employing both the 12- and 32-channel head coils. Diffusion-weighted echoplanar images were acquired in both the axial (n=12) and coronal (n=10) planes, comparing scans without parallel imaging to those with parallel imaging factors (IPAT) of 2 and 4. These results were compared to scans acquired using a fast spin echo (FSE) BLADE diffusion weighted technique (Figure 1). Higher IPAT factors were evaluated due to an interest in further reducing bulk susceptibility artifacts (Figure 2). These are prominent in echoplanar DWI at interfaces between air-filled sinuses and the brain, and are substantially greater at 3 T as opposed to 1.5 T. Click Figure Callout to View Figure

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FSE BLADE DWI continued The FSE BLADE DWI approach was evaluated, although intrinsically of lower signal-to-noise ratio (SNR) than echoplanar DWI, due to the interest in providing images with little if any degradation due to bulk susceptibility artifact. BLADE (PROPELLER) represents an innovative imaging approach, in which k-space is sampled by multiple echo trains in a rotating, partially overlapping, fashion (like the rotation of a propeller), rather than in the standard rectilinear fashion. Each scan was performed twice to enable the determination of SNR measurements, since parallel imaging was employed. Region of interest measurements were performed in two different anatomical areas (cerebral white matter and peripheral cerebellum). In normal volunteers, the 32-channel head coil demonstrated an improvement in SNR in both anatomic regions as compared to the 12-channel coil. With echoplanar based DWI (and no IPAT), the improvement in the SNR was 43% for cerebral white matter and 67% for peripheral cerebellum.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FSE BLADE DWI continued Increasing the IPAT factor lead to a decrease in SNR in both the 32- and 12-channel coils. SNR remained however increased in each region of interest with the 32- vs. 12-channel coil with the implementation of parallel imaging. The use of an IPAT factor of 4, permitted by the 32- channel coil, substantially reduced bulk susceptibility artifact from air- brain interfaces, and was demonstrated in axial, coronal, and sagittal imaging (Figure 3). Diffusion weighted imaging was possible with the BLADE FSE sequence in a reasonable scan time (3:48 min:sec) by use of the 32-channel coil (Figure 4). Three scan trace diffusion weighted imaging (BLADE FSE), using a 192 x 192 matrix, was performed in patients in all three orthogonal planes, with equivalent depiction of acute to early subacute infarcts to echoplanar based DWI, but with elimination of bulk susceptibility artifacts. Click Figure Callout to View Figure

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design 2D T1-weighted FLASH A comparison of T1-weighted imaging using the 12- and 32-channel coils was performed in 10 normal volunteers and 6 patients. T1-weighted axial and sagittal 2D short TE gradient echo (GRE) images were acquired using both the 12- and 32-channel coils. Two acquisitions (averages) were employed for the 12-channel coil scans, and one acquisition for the 32- channel coil scans (Figure 5). Scan times were 2:10 and 1:52 min:sec for the sagittal and axial scans using the 12-channel coil, and 1:12 and 0:56 min:sec for the 32-channel coil. This work was performed specifically to evaluate the capability of the 32-channel coil using approximately half scan time. Click Figure Callout to View Figure

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design T1-weighted turboFLASH BLADE Additional T1-weighted axial 2D BLADE turboFLASH (0.9 x 0.9 x 4 mm 3 voxel dimension, scan time = 2:45 min:sec) scans were acquired using the 32-channel coil only. Despite the almost 2-fold reduction in scan time used with the 32-channel coil, on short TE GRE T1-weighted imaging, there was a 26% increase in SNR in cerebral white matter and a 10% increase in the cerebellum. Acquisition of the 2D BLADE turboFLASH scan using the 32-channel coil led to very reproducible, motion insensitive T1-weighted scans of high image quality with improved gray-white matter contrast when compared to the short TE GRE sequence (Figure 6). Click Figure Callout to View Figure

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design TWIST (Time-resolved Angiography With Interleaved Stochastic Trajectories) TWIST was evaluated for its performance in visualization of the arterial and venous vasculature, in 22 exams (in an experimental animal model), using a scan with voxel dimensions of 1.2 x 1 x 1 mm 3, IPAT=3, and acquisition time of 1.95 sec ("3-D multiphasic low dose contrast enhanced MR angiography using TWIST on a 32-channel head coil at 3 Tesla: Comparison of a conventional gadolinium chelate with a high relaxivity agent", European Congress of Radiology 2008, Giesel F et al). Excellent visualization in particular of the arterial system was demonstrated, despite use of almost 1/3rd the normal contrast dose (0.04 mmol/kg, MultiHance). With the recognition of nephrogenic systemic fibrosis, gadolinium chelate administration in patients with renal failure has become a major concern, and in particular accumulated dosage. The 32-channel coil should allow low dose contrast enhanced MR angiography with high temporal and spatial resolution of both the arterial and venous systems of the brain.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FLAIR and T2-weighted BLADE; SPACE Patient studies included, in addition to the results previously discussed (such as application in T1-weighted imaging, figures 5, 6), acquisition of half scan time sequences (with the 32-channel coil) using FLAIR and T2-weighted BLADE (Figure 7). Image quality was equivalent to scans with twice the acquisition time using the 12-channel coil in the cerebral hemispheres, with slightly degraded image quality in the posterior fossa. Additional scan sequences evaluated in patients included 3D MP-RAGE, FLAIR SPACE, T2-weighted SPACE, and double inversion recovery. The 32-channel coil was employed in these 3D scan acquisitions to provide higher voxel resolution within a reasonable scan time (Figure 8). Click Figure Callout to View Figure After review of Figure 7& 8 this concludes the main exhibit. You may click here to jump to the Conclusion and Author Correspondence Information slides. or click elsewhere to review Figures 1-8 once more prior to the Conclusion.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design Diffusion weighted scans are illustrated in a normal volunteer, all acquired with the 32-channel head coil at 3 T. The first three images are with echoplanar diffusion weighted imaging, comparing (A) the use of no parallel imaging, to implementation of parallel imaging factors (IPAT) of (B) 2 and (C) 4. Bulk susceptibility artifacts become less evident as IPAT is increased. The pons is relatively poorly depicted with an IPAT of 4, due to lower SNR. (D) illustrates the equivalent BLADE fast spin echo (FSE) diffusion weighted scan, with no bulk susceptibility artifacts evident. The high SNR of the 32-channel coil makes acquisition of this scan possible within a reasonable time (3:48 min:sec). All scans were acquired with a b value of FIGURE 1 AB CD Click on thumbnails for a larger view.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FIGURE 2 The same four scan types are illustrated as in Figure 1, in a different normal volunteer, with acquisition in the sagittal (A-D) and coronal (E-H) planes (A & E no IPAT, B & F IPAT 2, C & G IPAT 4). The capability of the 32-channel coil to perform well (in all planes) with high IPAT values (=4, in C & G) is noted, together with the advantage of (D & H) the BLADE FSE diffusion weighted scan (made possible by the SNR of the 32-channel coil) for elimination of bulk susceptibility artifacts. All scans were acquired with a 192 matrix. AB CD E F GH Click on thumbnails for a larger view.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FIGURE 3 A patient with multiple punctate acute infarcts is illustrated in (A) with echoplanar diffusion weighted imaging using the 12-channel coil and an IPAT factor of 2. The capability of the 32-channel coil for higher IPAT factors, and thus less bulk susceptibility artifact, in all planes is illustrated in (B-D) with IPAT 4 scans in the axial, sagittal, and coronal planes. AB CD Click on thumbnails for a larger view.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FIGURE 4 Diffusion weighted scans in a patient with an acute thalamic infarct are compared. (A) was acquired with the 12-channel coil and an IPAT of 2. (B-D) were acquired with the 32-channel coil. (B) and (C) are echoplanar technique, with an IPAT of 4, while (D) is the BLADE FSE diffusion weighted scan. Note the reduction in susceptibility artifact with IPAT 4 in (B) as compared to (A), and the viability of IPAT 4 scans in both the axial and coronal planes with the 32-channel coil. Note also the elimination of bulk susceptibility artifact (seen in B, arrow, in this instance originating from the frontal sinus) using the BLADE FSE diffusion weighted approach. AB CD Click on thumbnails for a larger view.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FIGURE 5 A scan acquired with the 12-channel coil using a short TE 2D T1- weighted FLASH scan with 2 averages and an acquisition time of 1:52 is compared with scans acquired with the 32-channel coil using the same FLASH scan but with 1 average and an acquisition time of 0:56, together with a 2D BLADE turboFLASH scan with acquisition time of 2:45. All scans are in a normal volunteer. Click on thumbnails for a larger view.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FIGURE 6 Two scans are illustrated, both acquired with the 32-channel coil, in a patient with enhancing (active) multiple sclerosis plaques. The first scan is a short TE T1-weighted 2D FLASH, with voxel dimensions of 0.9 x 0.9 x 4 mm 3, which is substantially degraded (by image blurring) due to patient motion despite the very short scan time (0:56 min:sec) made possible by use of the 32-channel coil. The second scan is a T1-weighted 2D turboFLASH BLADE, with equivalent voxel dimension, acquired in 2:45 min:sec. Note the marked improvement in image quality on the BLADE scan, with elimination of the blurring noted in the first scan due to patient motion. Click on thumbnails for a larger view.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FIGURE 7 Scans are illustrated in a patient with brain metastases. (A, B) Short TE 2D T1-weighted FLASH scans are presented, comparing a scan acquired (A) with the 12-channel coil in a 1:52 min:sec scan time to that acquired (B) with the 32-channel coil in a 0:56 min:sec scan time. Image quality is equivalent for depiction of the large enhancing parenchymal brain metastasis, as well as two smaller metastases. (C, D) FLAIR and T2-weighted BLADE 2D axial scans are also illustrated, both acquired with the 32-channel coil. An IPAT factor of 2 was used for both scans, with these scans typically performed when using the 12-channel coil without IPAT, leading to almost a 2 fold reduction in scan time. In this instance, the scan times were 1:03*2 and 0:28*2 min:sec, with both scans providing whole brain coverage using a 4 mm slice thickness. AB CD Click on thumbnails for a larger view.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FIGURE 8 A.9 x.9 x.9 mm 3 voxel size, 2:12 min:sec acquisition time, T2-weighted SPACE scan is illustrated, acquired with the 32-channel coil. An arteriovenous malformation is noted in the posterior fossa, illustrated with high image quality on reformatted images in the sagittal, coronal, and axial planes. Click on thumbnails for a larger view.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design CONCLUSION Overall the 32-channel coil represents a major advance when compared to all previous FDA approved 3 T head coil designs due both to improved SNR and its parallel imaging capabilities. Additional important applications, not discussed, include MR spectroscopy and fMRI.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design Author Correspondence Information: Val M. Runge, MD Editor-in-Chief, Investigative Radiology Robert and Alma Moreton Centennial Chair in Radiology Scott and White Clinic and Hospital Texas A&M University Health Science Center Department of Radiology 2401 South 31 st St. Temple, TX (254)

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design Diffusion weighted scans are illustrated in a normal volunteer, all acquired with the 32-channel head coil at 3 T. The first three images are with echoplanar diffusion weighted imaging, comparing (A) the use of no parallel imaging, to implementation of parallel imaging factors (IPAT) of (B) 2 and (C) 4. Bulk susceptibility artifacts become less evident as IPAT is increased. The pons is relatively poorly depicted with an IPAT of 4, due to lower SNR. (D) illustrates the equivalent BLADE fast spin echo (FSE) diffusion weighted scan, with no bulk susceptibility artifacts evident. The high SNR of the 32-channel coil makes acquisition of this scan possible within a reasonable time (3:48 min:sec). All scans were acquired with a b value of FIGURE 1 AB CD CLICK TO RETURN TO PRESENTATION Click on thumbnails for a larger view.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FIGURE 2 The same four scan types are illustrated as in Figure 1, in a different normal volunteer, with acquisition in the sagittal (A-D) and coronal (E-H) planes (A & E no IPAT, B & F IPAT 2, C & G IPAT 4). The capability of the 32-channel coil to perform well (in all planes) with high IPAT values (=4, in C & G) is noted, together with the advantage of (D & H) the BLADE FSE diffusion weighted scan (made possible by the SNR of the 32-channel coil) for elimination of bulk susceptibility artifacts. All scans were acquired with a 192 matrix. CLICK TO RETURN TO PRESENTATION Click on thumbnails for a larger view. AB CD E F GH

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FIGURE 3 A patient with multiple punctate acute infarcts is illustrated in (A) with echoplanar diffusion weighted imaging using the 12-channel coil and an IPAT factor of 2. The capability of the 32-channel coil for higher IPAT factors, and thus less bulk susceptibility artifact, in all planes is illustrated in (B-D) with IPAT 4 scans in the axial, sagittal, and coronal planes. AB CD CLICK TO RETURN TO PRESENTATION Click on thumbnails for a larger view.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FIGURE 4 Diffusion weighted scans in a patient with an acute thalamic infarct are compared. (A) was acquired with the 12-channel coil and an IPAT of 2. (B-D) were acquired with the 32-channel coil. (B) and (C) are echoplanar technique, with an IPAT of 4, while (D) is the BLADE FSE diffusion weighted scan. Note the reduction in susceptibility artifact with IPAT 4 in (B) as compared to (A), and the viability of IPAT 4 scans in both the axial and coronal planes with the 32-channel coil. Note also the elimination of bulk susceptibility artifact (seen in B, arrow, in this instance originating from the frontal sinus) using the BLADE FSE diffusion weighted approach. AB CD CLICK TO RETURN TO PRESENTATION Click on thumbnails for a larger view.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FIGURE 5 A scan acquired with the 12-channel coil using a short TE 2D T1- weighted FLASH scan with 2 averages and an acquisition time of 1:52 is compared with scans acquired with the 32-channel coil using the same FLASH scan but with 1 average and an acquisition time of 0:56, together with a 2D BLADE turboFLASH scan with acquisition time of 2:45. All scans are in a normal volunteer. CLICK TO RETURN TO PRESENTATION Click on thumbnails for a larger view.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FIGURE 6 Two scans are illustrated, both acquired with the 32-channel coil, in a patient with enhancing (active) multiple sclerosis plaques. The first scan is a short TE T1-weighted 2D FLASH, with voxel dimensions of 0.9 x 0.9 x 4 mm 3, which is substantially degraded (by image blurring) due to patient motion despite the very short scan time (0:56 min:sec) made possible by use of the 32-channel coil. The second scan is a T1-weighted 2D turboFLASH BLADE, with equivalent voxel dimension, acquired in 2:45 min:sec. Note the marked improvement in image quality on the BLADE scan, with elimination of the blurring noted in the first scan due to patient motion. CLICK TO RETURN TO PRESENTATION Click on thumbnails for a larger view.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FIGURE 7 Scans are illustrated in a patient with brain metastases. (A, B) Short TE 2D T1-weighted FLASH scans are presented, comparing a scan acquired (A) with the 12-channel coil in a 1:52 min:sec scan time to that acquired (B) with the 32-channel coil in a 0:56 min:sec scan time. Image quality is equivalent for depiction of the large enhancing parenchymal brain metastasis, as well as two smaller metastases. (C, D) FLAIR and T2-weighted BLADE 2D axial scans are also illustrated, both acquired with the 32-channel coil. An IPAT factor of 2 was used for both scans, with these scans typically performed when using the 12-channel coil without IPAT, leading to almost a 2 fold reduction in scan time. In this instance, the scan times were 1:03*2 and 0:28*2 min:sec, with both scans providing whole brain coverage using a 4 mm slice thickness. AB CD CLICK TO RETURN TO PRESENTATION Click on thumbnails for a larger view.

Advanced Clinical Brain Imaging at 3 T – SNR and Parallel Imaging Improvements Offered by a 32 Channel Head Coil Design FIGURE 8 A.9 x.9 x.9 mm 3 voxel size, 2:12 min:sec acquisition time, T2-weighted SPACE scan is illustrated, acquired with the 32-channel coil. An arteriovenous malformation is noted in the posterior fossa, illustrated with high image quality on reformatted images in the sagittal, coronal, and axial planes. CLICK TO RETURN TO PRESENTATION Click on thumbnails for a larger view.

AB CD Figure 1 - Diffusion weighted scans are illustrated in a normal volunteer, all acquired with the 32-channel head coil at 3 T. The first three images are with echoplanar diffusion weighted imaging, comparing (A) the use of no parallel imaging, to implementation of parallel imaging factors (IPAT) of (B) 2 and (C) 4. Bulk susceptibility artifacts become less evident as IPAT is increased. The pons is relatively poorly depicted with an IPAT of 4, due to lower SNR. (D) illustrates the equivalent BLADE fast spin echo (FSE) diffusion weighted scan, with no bulk susceptibility artifacts evident. The high SNR of the 32-channel coil makes acquisition of this scan possible within a reasonable time (3:48 min:sec). All scans were acquired with a b value of 1000.

AB CD EF GH Figure 2 - The same four scan types are illustrated as in Figure 1, in a different normal volunteer, with acquisition in the sagittal (A-D) and coronal (E-H) planes (A & E no IPAT, B & F IPAT 2, C & G IPAT 4). The capability of the 32-channel coil to perform well (in all planes) with high IPAT values (=4, in C & G) is noted, together with the advantage of (D & H) the BLADE FSE diffusion weighted scan (made possible by the SNR of the 32-channel coil) for elimination of bulk susceptibility artifacts. All scans were acquired with a 192 matrix.

AB CD Figure 3 - A patient with multiple punctate acute infarcts is illustrated in (A) with echoplanar diffusion weighted imaging using the 12-channel coil and an IPAT factor of 2. The capability of the 32-channel coil for higher IPAT factors, and thus less bulk susceptibility artifact, in all planes is illustrated in (B-D) with IPAT 4 scans in the axial, sagittal, and coronal planes.

AB CD Figure 4 - Diffusion weighted scans in a patient with an acute thalamic infarct are compared. (A) was acquired with the 12-channel coil and an IPAT of 2. (B-D) were acquired with the 32-channel coil. (B) and (C) are echoplanar technique, with an IPAT of 4, while (D) is the BLADE FSE diffusion weighted scan. Note the reduction in susceptibility artifact with IPAT 4 in (B) as compared to (A), and the viability of IPAT 4 scans in both the axial and coronal planes with the 32- channel coil. Note also the elimination of bulk susceptibility artifact (seen in B, arrow, in this instance originating from the frontal sinus) using the BLADE FSE diffusion weighted approach.

Figure 5 - A scan acquired with the 12-channel coil using a short TE 2D T1-weighted FLASH scan with 2 averages and an acquisition time of 1:52 is compared with scans acquired with the 32-channel coil using the same FLASH scan but with 1 average and an acquisition time of 0:56, together with a 2D BLADE turboFLASH scan with acquisition time of 2:45. All scans are in a normal volunteer.

Figure 6 - Two scans are illustrated, both acquired with the 32-channel coil, in a patient with enhancing (active) multiple sclerosis plaques. The first scan is a short TE T1-weighted 2D FLASH, with voxel dimensions of 0.9 x 0.9 x 4 mm 3, which is substantially degraded (by image blurring) due to patient motion despite the very short scan time (0:56 min:sec) made possible by use of the 32-channel coil. The second scan is a T1-weighted 2D turboFLASH BLADE, with equivalent voxel dimension, acquired in 2:45 min:sec. Note the marked improvement in image quality on the BLADE scan, with elimination of the blurring noted in the first scan due to patient motion.

AB CD Figure 7 - Scans are illustrated in a patient with brain metastases. (A, B) Short TE 2D T1-weighted FLASH scans are presented, comparing a scan acquired (A) with the 12-channel coil in a 1:52 min:sec scan time to that acquired (B) with the 32-channel coil in a 0:56 min:sec scan time. Image quality is equivalent for depiction of the large enhancing parenchymal brain metastasis, as well as two smaller metastases. (C, D) FLAIR and T2-weighted BLADE 2D axial scans are also illustrated, both acquired with the 32-channel coil. An IPAT factor of 2 was used for both scans, with these scans typically performed when using the 12-channel coil without IPAT, leading to almost a 2 fold reduction in scan time. In this instance, the scan times were 1:03*2 and 0:28*2 min:sec, with both scans providing whole brain coverage using a 4 mm slice thickness.

Figure 8 - A.9 x.9 x.9 mm 3 voxel size, 2:12 min:sec acquisition time, T2-weighted SPACE scan is illustrated, acquired with the 32-channel coil. An arteriovenous malformation is noted in the posterior fossa, illustrated with high image quality on reformatted images in the sagittal, coronal, and axial planes.