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Time-Efficient Breath-Hold Abdominal MRI at 3.0 T

M. Louis Lauzon1, Houman Mahallati1 and Richard Frayne1

1 All authors: Departments of Radiology and Clinical Neurosciences, University of Calgary, The Seaman Family MR Research Centre, Foothills Medical Centre, 1403-29th St. NW, Calgary, AB, Canada T2N 2T9.


Figure 1
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  		Fig. 1A —Dual-echo gradient-recalled echo (TR, 150 milliseconds; flip angle, 75°; slice thickness, 7.5 mm; breath-hold, 19 seconds). Conventional implementation first-echo (TE = 2.4 milliseconds; fat and water in-phase; nine slices) (A) and second-echo (TE = 5.8 milliseconds; fat and water opposed-phase; nine slices) (B) images.

 

Figure 2
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  		Fig. 1B —Dual-echo gradient-recalled echo (TR, 150 milliseconds; flip angle, 75°; slice thickness, 7.5 mm; breath-hold, 19 seconds). Conventional implementation first-echo (TE = 2.4 milliseconds; fat and water in-phase; nine slices) (A) and second-echo (TE = 5.8 milliseconds; fat and water opposed-phase; nine slices) (B) images.

 

Figure 3
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  		Fig. 1C —Dual-echo gradient-recalled echo (TR, 150 milliseconds; flip angle, 75°; slice thickness, 7.5 mm; breath-hold, 19 seconds). Time-efficient implementation first-echo (TE = 1.3 milliseconds; fat and water opposed-phase; 20 slices) (C) and second-echo (TE = 2.3 milliseconds; fat and water in-phase; 20 slices) (D) images. Note extra signal loss (B, arrow) in conventional opposed-phase TE (5.8 milliseconds) compared with our time-efficient opposed-phase TE (1.3 milliseconds) (C). Although slices do not match exactly because they are taken from two separate breath-holds, adjacent opposed-phase slices directly superior and inferior (not shown) also showed greater signal loss in stomach area (arrow, B) for conventional implementation compared with time-efficient acquisition. Because degree of gastric distention due to air and fluid content was visually identical between the two acquisitions (taken about 1 minute apart), increased signal loss in conventional implementation is most likely due to greater susceptibility-induced dephasing at longer TE.

 

Figure 4
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  		Fig. 1D —Dual-echo gradient-recalled echo (TR, 150 milliseconds; flip angle, 75°; slice thickness, 7.5 mm; breath-hold, 19 seconds). Time-efficient implementation first-echo (TE = 1.3 milliseconds; fat and water opposed-phase; 20 slices) (C) and second-echo (TE = 2.3 milliseconds; fat and water in-phase; 20 slices) (D) images. Note extra signal loss (B, arrow) in conventional opposed-phase TE (5.8 milliseconds) compared with our time-efficient opposed-phase TE (1.3 milliseconds) (C). Although slices do not match exactly because they are taken from two separate breath-holds, adjacent opposed-phase slices directly superior and inferior (not shown) also showed greater signal loss in stomach area (arrow, B) for conventional implementation compared with time-efficient acquisition. Because degree of gastric distention due to air and fluid content was visually identical between the two acquisitions (taken about 1 minute apart), increased signal loss in conventional implementation is most likely due to greater susceptibility-induced dephasing at longer TE.

 

Figure 5
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  		Fig. 2A —Single-shot fast spin-echo (TE = 90 milliseconds; flip angle, 90°; slice thickness, 7.0 mm). Conventional implementation (TR = 1,510 milliseconds; breath-hold, 19 seconds; 13 slices) (A) and time-efficient implementation (TR = 530 milliseconds; breath-hold, 12 seconds; 22 slices) (B) images. Image quality is visually similar between the two implementations, although signal-to-noise ratios differ (see Table 3) and there are subtle tissue contrast differences. Time-efficient image shows hypointensity in major organs (liver, spleen, skeletal muscle, and kidney), but CSF and fat appear visually similar between the two implementations.

 

Figure 6
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  		Fig. 2B —Single-shot fast spin-echo (TE = 90 milliseconds; flip angle, 90°; slice thickness, 7.0 mm). Conventional implementation (TR = 1,510 milliseconds; breath-hold, 19 seconds; 13 slices) (A) and time-efficient implementation (TR = 530 milliseconds; breath-hold, 12 seconds; 22 slices) (B) images. Image quality is visually similar between the two implementations, although signal-to-noise ratios differ (see Table 3) and there are subtle tissue contrast differences. Time-efficient image shows hypointensity in major organs (liver, spleen, skeletal muscle, and kidney), but CSF and fat appear visually similar between the two implementations.

 

Figure 7
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  		Fig. 3A —Three-dimensional true fast imaging with steady-state free precession (true FISP) (TE = 0.8 milliseconds; flip angle, 40°; slice thickness, 6.0 mm; breath-hold, 21 seconds). Conventional implementation (TR = 7.2 milliseconds; 12 slices) (A) and time-efficient implementation (TR = 2.5 milliseconds, 32 slices) (B) images. Note aortic flow-related ghosting artifacts (thick arrows) and banding artifacts (thin arrows) in conventional implementation (A) compared with time-efficient, shorter-TR true FISP implementation (B).

 

Figure 8
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  		Fig. 3B —Three-dimensional true fast imaging with steady-state free precession (true FISP) (TE = 0.8 milliseconds; flip angle, 40°; slice thickness, 6.0 mm; breath-hold, 21 seconds). Conventional implementation (TR = 7.2 milliseconds; 12 slices) (A) and time-efficient implementation (TR = 2.5 milliseconds, 32 slices) (B) images. Note aortic flow-related ghosting artifacts (thick arrows) and banding artifacts (thin arrows) in conventional implementation (A) compared with time-efficient, shorter-TR true FISP implementation (B).

 

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