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Simple Changes to 1.5-T MRI Abdomen and Pelvis Protocols to Optimize Results at 3 T

¹ Both authors: Department of Diagnostic Radiology, Yale University School of Medicine, PO Box 208042, New Haven, CT 06520-8042.

View larger version (150K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1A —63-year-old man with ascites. Axial T2-weighted single-shot fast spin-echo image at 3 T through mid abdomen shows loss of signal in center of patient volume secondary to dielectric effect.

View larger version (167K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1B —63-year-old man with ascites. Axial T2-weighted single-shot fast spin-echo image at 1.5 T.

View larger version (51K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2A —46-year-old woman with normal pelvis. Axial T1-weighted fast spin-echo images through pelvis at 3 T show large amount of dielectric artifact centrally (A) and resolution of artifact with dielectric pad (B).

View larger version (64K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2B —46-year-old woman with normal pelvis. Axial T1-weighted fast spin-echo images through pelvis at 3 T show large amount of dielectric artifact centrally (A) and resolution of artifact with dielectric pad (B).

View larger version (144K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3 — 26-year-old woman with abdominal pain. Axial T2-weighted single-shot fast spin-echo image through mid abdomen at 3 T with dielectric pad shows loss of signal in center of image despite use of pad. In some patients, dielectric pad cannot remove artifact completely.

View larger version (142K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4 —55-year-old man with cirrhosis, ascites, and elevated bilirubin level. Coronal T2-weighted single-shot fast spin-echo image through mid abdomen at 3 T with dielectric pad. Despite signal loss over center of liver secondary to dielectric effect, common duct (arrow) is clearly seen to ampulla. Duct is normal caliber. No obstructing mass or stone is present. This patient did not have biliary obstruction as a cause of increased bilirubin. In some patients, diagnosis is still made despite dielectric artifact. This patient should have been scanned on 1.5-T scanner.

View larger version (108K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5A —55-year-old woman with history of metastatic colon cancer to liver after wedge resection in right posterior lobe. T1-weighted gradient-echo image through liver with TE of 2.15 milliseconds obtained on 1.5-T scanner. At 1.5 T, this is an out-of-phase image and india ink artifact can be seen at interface of abdominal organs and peritoneal fat. Note amount of blooming around surgical clips in right posterior liver (arrow).

View larger version (100K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5B —55-year-old woman with history of metastatic colon cancer to liver after wedge resection in right posterior lobe. T1-weighted gradient-echo image through liver with TE of 2.3 milliseconds obtained on 3-T scanner. At 3 T, this is an in-phase image and no india ink artifact is seen. Note how much more blooming is seen around surgical clips (arrow) despite the same short TE.

View larger version (141K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 6A —46-year-old woman with history of breast cancer. Sagittal contrast-enhanced 3D T1-weighted fat-saturated fast spoiled gradient-recalled echo image obtained at 1.5 T through breast (TR/TE, 6.5/3.2; flip angle, 10°; voxel size, 3 x 0.78 x 1.04 mm for a volume of 2.4 mm3). Note amount of blooming artifact from surgical clips (arrow).

View larger version (113K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 6B —46-year-old woman with history of breast cancer. Sagittal contrast-enhanced 3D T1-weighted fat-saturated fast spoiled gradient-recalled echo image obtained at 3 T through breast (6.7/2.6; flip angle, 10°; voxel size, 2.2 x 0.625 x 1.04 mm for a volume of 1.4 mm3). Amount of blooming from surgical clips (arrow) is the same as on image obtained at 1.5 T. This is caused by shorter TE and higher spatial resolution.

View larger version (92K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 7A —35-year-old woman with pelvic pain; images obtained at 3 T. Unenhanced axial T1-weighted fat-saturated 3D fast spoiled gradient-recalled echo image through pelvis (TR/TE, 3.5/1.98; flip angle, 12°; bandwidth, 63 kHz; imaging time, 27 seconds; field of view, 36 cm; slice thickness, 4 mm; matrix, 320 x 256).

View larger version (87K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 7B —35-year-old woman with pelvic pain; images obtained at 3 T. Unenhanced axial T1-weighted fat-saturated 3D fast spoiled gradient-recalled echo image through pelvis (3.8/1.69; flip angle, 12°; bandwidth, 83 kHz; imaging time, 24 seconds; field of view, 36 cm; slice thickness, 4 mm; matrix, 320 x 256).

View larger version (92K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 7C —35-year-old woman with pelvic pain; images obtained at 3 T. Unenhanced axial T1-weighted fat-saturated 3D fast spoiled gradient-recalled echo image through pelvis (3.5/1.55; flip angle, 12°; bandwidth, 100 kHz; imaging time, 22 seconds; field of view, 36 cm; slice thickness, 4 mm; matrix, 320 x 256). There is no visible difference in signal between images A, B, and C. Voxel size is the same. Increased bandwidth (which reduces signal) results in decreased TE (which increases signal due to less T2* decay), and these effects counteract each other. However, breath-hold time is shorter with longer-bandwidth acquisition, which results in less potential motion artifact from breathing.

View larger version (118K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 8A —25-year-old man with geographic fatty infiltration of liver. T1-weighted out-of-phase 2D gradient-echo image obtained at 1.5 T (TR/TE, 250/2.2; flip angle, 80°; slice thickness, 5 mm; interval, 5 mm; matrix, 288 x 224).

View larger version (113K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 8B —25-year-old man with geographic fatty infiltration of liver. T1-weighted in-phase 2D gradient-echo image obtained at 1.5 T (250/4.4; flip angle, 80°; slice thickness, 5 mm; interval, 5 mm; matrix, 288 x 224). Images A and B were obtained in the same breath-hold, which ensures that TR, flip angle, field of view, matrix, and receiver bandwidth are identical for each acquisition and eliminates possibility of image misregistration.

View larger version (107K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 8C —25-year-old man with geographic fatty infiltration of liver. T1-weighted out-of-phase 2D gradient-echo image obtained at 3 T (175/1.4; flip angle, 60°; slice thickness, 5 mm; interval, 5 mm; matrix, 288 x 224).

View larger version (98K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 8D —25-year-old man with geographic fatty infiltration of liver. T1-weighted in-phase 2D gradient-echo image obtained at 3 T (175/2.2; flip angle, 60°; slice thickness, 5 mm; interval, 5 mm; matrix, 288 x 224). Images C and D are obtained in separate breath-holds. If technologist inadvertently changes TR or matrix to optimize breath-hold time, the two acquisitions will not match. Also, if patient breathes differently between the two acquisitions, image misregistration will result. Compared with A and B, contrast between liver and spleen in images C and D is decreased. Shorter TR and smaller flip angle, combined with longer T1 relaxation times at 3 T, result in less T1 weighting.

View larger version (126K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 9A —45-year-old man with diffuse fatty infiltration of liver. T1-weighted out-of-phase 2D gradient-echo image obtained at 3 T (TR/TE, 175/1.4; flip angle, 60°; slice thickness, 5 mm; interval, 5 mm; matrix, 288 x 224).

View larger version (118K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 9B —45-year-old man with diffuse fatty infiltration of liver. T1-weighted in-phase 2D gradient-echo image obtained at 3 T (175/2.2; flip angle, 60°; slice thickness, 5 mm; interval, 5 mm; matrix, 288 x 224). Images A and B are obtained in separate breath-holds.

View larger version (128K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 9C —45-year-old man with diffuse fatty infiltration of liver. T1-weighted out-of-phase 3D dual-echo fast spoiled gradient-recalled echo image obtained at 3 T (4/1.3; flip angle, 12°; slice thickness, 4 mm; interval, 4 mm; matrix, 320 x 224).

View larger version (125K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 9D —45-year-old man with diffuse fatty infiltration of liver. T1-weighted in-phase 3D dual-echo fast spoiled gradient-recalled echo image obtained at 3 T (4/2.2; flip angle, 12°; slice thickness, 4 mm; interval, 4 mm; matrix, 320 x 224). Images C and D are obtained in same breath-hold. Liver is darker in C than in A because TE is closer to true out-of-phase TE of 1.1 milliseconds. At time of this writing, this sequence is not a commercial product. However, this should solve reported problems with chemical shift imaging at 3 T.

View larger version (121K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10A —34-year-old healthy female volunteer with normal liver. Axial T2-weighted single-shot fast spin-echo images through abdomen at 3 T with varying effective TEs of 70 (A), 90 (B), 105 (C), 120 (D), and 140 (E) milliseconds. Each image was acquired as a single slice in a single breath-hold (field of view, 36 cm; slice thickness, 5 mm; interval, 6 mm; matrix, 320 x 224). Note progressive signal loss throughout liver and remainder of abdomen as TE increases from 70 to 140 milliseconds. At 1.5 T, typical TE for T2-weighted single-shot fast spin-echo acquisition is 100 milliseconds. At 3 T, we use TE of 70 milliseconds.

View larger version (115K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10B —34-year-old healthy female volunteer with normal liver. Axial T2-weighted single-shot fast spin-echo images through abdomen at 3 T with varying effective TEs of 70 (A), 90 (B), 105 (C), 120 (D), and 140 (E) milliseconds. Each image was acquired as a single slice in a single breath-hold (field of view, 36 cm; slice thickness, 5 mm; interval, 6 mm; matrix, 320 x 224). Note progressive signal loss throughout liver and remainder of abdomen as TE increases from 70 to 140 milliseconds. At 1.5 T, typical TE for T2-weighted single-shot fast spin-echo acquisition is 100 milliseconds. At 3 T, we use TE of 70 milliseconds.

View larger version (114K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10C —34-year-old healthy female volunteer with normal liver. Axial T2-weighted single-shot fast spin-echo images through abdomen at 3 T with varying effective TEs of 70 (A), 90 (B), 105 (C), 120 (D), and 140 (E) milliseconds. Each image was acquired as a single slice in a single breath-hold (field of view, 36 cm; slice thickness, 5 mm; interval, 6 mm; matrix, 320 x 224). Note progressive signal loss throughout liver and remainder of abdomen as TE increases from 70 to 140 milliseconds. At 1.5 T, typical TE for T2-weighted single-shot fast spin-echo acquisition is 100 milliseconds. At 3 T, we use TE of 70 milliseconds.

View larger version (114K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10D —34-year-old healthy female volunteer with normal liver. Axial T2-weighted single-shot fast spin-echo images through abdomen at 3 T with varying effective TEs of 70 (A), 90 (B), 105 (C), 120 (D), and 140 (E) milliseconds. Each image was acquired as a single slice in a single breath-hold (field of view, 36 cm; slice thickness, 5 mm; interval, 6 mm; matrix, 320 x 224). Note progressive signal loss throughout liver and remainder of abdomen as TE increases from 70 to 140 milliseconds. At 1.5 T, typical TE for T2-weighted single-shot fast spin-echo acquisition is 100 milliseconds. At 3 T, we use TE of 70 milliseconds.

View larger version (109K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10E —34-year-old healthy female volunteer with normal liver. Axial T2-weighted single-shot fast spin-echo images through abdomen at 3 T with varying effective TEs of 70 (A), 90 (B), 105 (C), 120 (D), and 140 (E) milliseconds. Each image was acquired as a single slice in a single breath-hold (field of view, 36 cm; slice thickness, 5 mm; interval, 6 mm; matrix, 320 x 224). Note progressive signal loss throughout liver and remainder of abdomen as TE increases from 70 to 140 milliseconds. At 1.5 T, typical TE for T2-weighted single-shot fast spin-echo acquisition is 100 milliseconds. At 3 T, we use TE of 70 milliseconds.

View larger version (137K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 11A —34-year-old healthy female volunteer with normal pancreas. Axial T2-weighted single-shot fast spin-echo images through abdomen at 3 T with (A) and without (B) parallel imaging (TE, 70 milliseconds; field of view, 36 cm; slice thickness, 5 mm; interval, 6 mm; matrix, 320 x 224). Parallel imaging acceleration factor in A is 2. Edges in A are sharper than in B.

View larger version (137K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 11B —34-year-old healthy female volunteer with normal pancreas. Axial T2-weighted single-shot fast spin-echo images through abdomen at 3 T with (A) and without (B) parallel imaging (TE, 70 milliseconds; field of view, 36 cm; slice thickness, 5 mm; interval, 6 mm; matrix, 320 x 224). Parallel imaging acceleration factor in A is 2. Edges in A are sharper than in B.

View larger version (159K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 12A —34-year-old healthy female volunteer with normal uterus. Sagittal T2-weighted fast spin-echo images through pelvis at 3 T with different effective TEs as indicated (field of view, 24 cm; slice thickness, 4 mm, interval, 5 mm; echo-train length, 28; matrix, 320 x 288). Notice how soft-tissue contrast in uterus changes as TE changes from 70 to 140 milliseconds. At 1.5 T, typical TE for T2-weighted fast spin-echo in pelvis is 100 milliseconds. At 3 T, we use TE of 120–140 milliseconds, which also produces good contrast in prostate.

View larger version (177K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 12B —34-year-old healthy female volunteer with normal uterus. Sagittal T2-weighted fast spin-echo images through pelvis at 3 T with different effective TEs as indicated (field of view, 24 cm; slice thickness, 4 mm, interval, 5 mm; echo-train length, 28; matrix, 320 x 288). Notice how soft-tissue contrast in uterus changes as TE changes from 70 to 140 milliseconds. At 1.5 T, typical TE for T2-weighted fast spin-echo in pelvis is 100 milliseconds. At 3 T, we use TE of 120–140 milliseconds, which also produces good contrast in prostate.

View larger version (164K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 12C —34-year-old healthy female volunteer with normal uterus. Sagittal T2-weighted fast spin-echo images through pelvis at 3 T with different effective TEs as indicated (field of view, 24 cm; slice thickness, 4 mm, interval, 5 mm; echo-train length, 28; matrix, 320 x 288). Notice how soft-tissue contrast in uterus changes as TE changes from 70 to 140 milliseconds. At 1.5 T, typical TE for T2-weighted fast spin-echo in pelvis is 100 milliseconds. At 3 T, we use TE of 120–140 milliseconds, which also produces good contrast in prostate.

View larger version (182K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 12D —34-year-old healthy female volunteer with normal uterus. Sagittal T2-weighted fast spin-echo images through pelvis at 3 T with different effective TEs as indicated (field of view, 24 cm; slice thickness, 4 mm, interval, 5 mm; echo-train length, 28; matrix, 320 x 288). Notice how soft-tissue contrast in uterus changes as TE changes from 70 to 140 milliseconds. At 1.5 T, typical TE for T2-weighted fast spin-echo in pelvis is 100 milliseconds. At 3 T, we use TE of 120–140 milliseconds, which also produces good contrast in prostate.

View larger version (170K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 12E —34-year-old healthy female volunteer with normal uterus. Sagittal T2-weighted fast spin-echo images through pelvis at 3 T with different effective TEs as indicated (field of view, 24 cm; slice thickness, 4 mm, interval, 5 mm; echo-train length, 28; matrix, 320 x 288). Notice how soft-tissue contrast in uterus changes as TE changes from 70 to 140 milliseconds. At 1.5 T, typical TE for T2-weighted fast spin-echo in pelvis is 100 milliseconds. At 3 T, we use TE of 120–140 milliseconds, which also produces good contrast in prostate.

View larger version (186K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 13A —72-year-old woman with pelvic pain and intramural fibroid. Sagittal (A) and axial (B) T2-weighted fast spin-echo images through pelvis at 3 T (TR/TE, 5,700/120; field of view, 24 cm; slice thickness, 4 mm; interval, 5 mm; matrix, 320 x 224). Echo-train length is 15; bandwidth is 60 kHz. Parallel imaging was used to reduce effective echo-train length. Frequency direction is superior-to-inferior on sagittal image and left-to-right on axial image. Saturation pulses were placed on anterior abdominal wall to reduce artifact from breathing. Image quality is poor.

View larger version (189K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 13B —72-year-old woman with pelvic pain and intramural fibroid. Sagittal (A) and axial (B) T2-weighted fast spin-echo images through pelvis at 3 T (TR/TE, 5,700/120; field of view, 24 cm; slice thickness, 4 mm; interval, 5 mm; matrix, 320 x 224). Echo-train length is 15; bandwidth is 60 kHz. Parallel imaging was used to reduce effective echo-train length. Frequency direction is superior-to-inferior on sagittal image and left-to-right on axial image. Saturation pulses were placed on anterior abdominal wall to reduce artifact from breathing. Image quality is poor.

View larger version (194K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 13C —72-year-old woman with pelvic pain and intramural fibroid. Sagittal (C) and axial (D) T2-weighted fast spin-echo images through pelvis (5,700/120; field of view, 24 cm; slice thickness, 5 mm; interval, 5 mm; matrix, 320 x 224). Echo-train length is 28. Parallel imaging was not used. Frequency direction is anterior-to-posterior on both sagittal and axial images. Image quality is significantly improved.

View larger version (181K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 13D —72-year-old woman with pelvic pain and intramural fibroid. Sagittal (C) and axial (D) T2-weighted fast spin-echo images through pelvis (5,700/120; field of view, 24 cm; slice thickness, 5 mm; interval, 5 mm; matrix, 320 x 224). Echo-train length is 28. Parallel imaging was not used. Frequency direction is anterior-to-posterior on both sagittal and axial images. Image quality is significantly improved.

View larger version (135K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 14A — 27-year-old woman with torsed ovary and fallopian tube. Axial T2-weighted fast spin-echo image through pelvis at 3 T (TR/TE, 5,700/120; field of view, 24 cm; slice thickness, 4 mm; interval, 5 mm; matrix, 320 x 224). Echo-train length is 28. Parallel imaging was not used. Frequency direction is anterior-to-posterior. Image is blurry because of bowel motion.

View larger version (145K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 14B — 27-year-old woman with torsed ovary and fallopian tube. Axial T2-weighted fast spin-echo image through pelvis after IV administration of 1 mg of glucagon (5,700/120; field of view, 24 cm; slice thickness, 4 mm; interval, 5 mm; matrix, 320 x 224). Echo-train length is 28. Parallel imaging was not used. Frequency direction is anterior-to-posterior. Tortuous, thickened fallopian tube is much more clearly seen (arrow) because artifact from bowel motion is reduced.

View larger version (174K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 15A —36-year-old healthy male volunteer. See Figures S15A and S15B at www.arrs.org for these cine imaging files. Single still image from stack of coronal single-shot fast spin-echo images through liver and biliary tree (field of view, 36 cm; slice thickness, 5 mm; interval, 6 mm; matrix, 320 x 224). TE is 70 milliseconds. Parallel imaging acceleration factor is 2. Stack was obtained during two separate breath-holds. Notice how diaphragm and liver bounce up and down on every other image. Although patient held his breath satisfactorily, breath-hold position was different for the two acquisitions. Images are difficult to scroll through, and a small gallstone could potentially be missed if it moved in and out of the imaging planes.

View larger version (168K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 15B —36-year-old healthy male volunteer. See Figures S15A and S15B at www.arrs.org for these cine imaging files. Single still image from stack of coronal single-shot fast spin-echo images through liver and biliary tree (field of view, 36 cm; slice thickness, 5 mm; interval, 6 mm; matrix, 320 x 224). TE is 70 milliseconds. Parallel imaging acceleration factor is 2. Stack was obtained using respiratory triggering. Notice how diaphragm and liver are in same position on each image. No misregistration is seen.

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