V. Nghiem,

Hanh

R. Brooke

J.

MD #{149}Robert Jr, MD #{149}King

Jeffrey,

The Pelvis: MR Imaging’

T2weighted

Fast

spin-echo (SE) T2-weighted resonance (MR) imaging images with highly T2weighted contrast in substantially reduced imaging times. In a prospecfive evaluation, fast SE T2-weighted imaging of the pelvis was compared with conventional SE T2-weighted imaging in 30 consecutive patients in whom pelvic pathologic conditions were suspected. Three reviewers independently analyzed the images for (a) overall image quality, (b) pelvic organ definition, (c) conspicuity of pelvic fluid, and (d) conspicuity of magnetic provides

pelvic

pathologic

conditions.

Fast

SE

images were rated superior to conventional SE T2-weighted images in 60% (54 of 90) of the case reviews for overall image quality, in 69% (62 of 90) for pelvic organ definition, in 63% (57 of 90) for conspicuity of pelvic fluid, and in 68% (43 of 63) for conspicuity of pelvic pathologic conditions. The fast SE examinations were typically three to four times faster than conventional SE T2-weighted examinations. No pathologic findings seen on conventional SE T2-weighted images were undetected on fast SE images. Fast SE images may replace conventional SE T2-weighted images in MR imaging of the pelvis. Index

terms:

Imaging

Magnetic

#{149} Pelvic

organs,

resonance (MR), rapid MR. 80.1214 #{149}Pelvis,

MR. 44.1214 Radiology

1992;

i85:213-217

1 From the Department ford University Medical Stanford, CA 94305-5105

R.B.J.,

K.C.P.L.,

nostic

Radiology

Michigan partment

G.H.C.);

and

of Radiology, StanCenter, 300 Pasteur Dr, (H.V.N., R.J.H., F.G.S., Department of Diag-

Imaging,

University

of

Hospital, Ann Arbor (I.R.F.); and Deof Radiology, Thomas Jefferson UniHospital, Philadelphia (R.M.S.). From the

versity i99i RSNA scientific assembly. Received March 24, 1992; revision requested May 13; revision

received print

June 15; accepted

requests to R.J.H. C RSNA, 1992

June

Herfkens,

C. P. Li, MD

22. Address

re-

I

MD

#{149}Isaac R. Francis, Robert M. Steiner,

#{149}

Fast

MD MD

F. Graham Sommer, Gary H. Glover, PhD

#{149}

MD

#{149}

Spin-Echo

detection and characterization of pelvic pathologic conditions, convenlionab spin-echo (SE) T2-weighted magnetic resonance (MR) imaging has been shown to be a highly sensitive modality (1-6). While it provides excellent depiction of pelvic pathologic conditions, the main disadvantage of this technique is the relatively long imaging lime. For this reason, there have been continued efforts to devebop new techniques to reduce the acquisition lime of T2-weighted

only one saturation pulse every 16 views, with an of 16). The use of fat supalso more important in fast because of the relatively hyperintense signal of lipid on fast SE images. The purpose of this study was to compare fast SE with the conventional SE T2-weighted technique in MR imaging of the pelvis.

images.

Patient

N

A fast SE sequence has recently been developed from the rapid acquisilion with relaxation enhancement (RARE) sequence of Henig (7) that is designed to provide conventional SE contrast in substantially shorter imaging times (up to 16 limes faster than with the standard SE sequence) (7-9). In the fast SE sequence, the initial 9#{216}0 pulse is followed by the acquisition of two to i6 echoes (echo train length), each acquired with a different phaseencoding value. The number of excitations required to obtain a full data set is thereby reduced by the same factor. For example, a fast SE image acquired with an echo train length of eight is eight times faster than conventional SE T2-weighted imaging. This substantial reduction in imaging limes allows a trade-off of the reduced imaging time for the use of longer repetition time and echo lime, larger matrix, and more signal averaging and fat suppression, while substanlial time savings are still maintamed. Since fat saturation (FAT SAT) pulses are 16 msec long, this causes a reduction in section number or an increase in imaging lime. Therefore, although fat suppression may be empboyed with both conventional SE or fast SE imaging, it is more practical to use fat suppression in fast SE imaging, due to the substantial time saving obtained with this type of pulse sequence (by using a saturation pulse for every repetition time; thus in fast

SE imaging, is used for echo train pression is SE imaging

MATERIALS

AND

METHODS

Population

Thirty consecutive patients (21 female and nine male) with suspected pelvic pathologic conditions were prospectively evaluated with MR imaging. The patients ranged in age from 9 days to 77 years (mean, 40 years). Twenty-one patients had abnormal studies with demonstrable pelvic pathologic conditions. Various pelvic pathologic conditions were seen in the 21 abnormal studies, including uterine myomas, lymphoma, metastatic disease to the bone and soft tissue of the pelvis, neurobbastoma, transitional cell carcinoma of the bladder, infection of soft tissue and hip joints, hydrosalpinx, cervical carcinoma, and uterine anomaly. The pelvic pathologic conditions were confirmed with either surgery or biopsy, or were presumed in cases of uterine myomas, metastastic disease in patients with known primary malignancy, and uterine anomalies.

Imaging

Protocols

Both standard SE T2-weighted and fast SE examinations were performed in all patients with a i.5-T Signa imager (GE Medical Systems, Milwaukee). Twentyeight examinations were performed with the body coil and two examinations, with a pelvic coil (anterior and posterior Helmholtz coils; Medical Advances, Milwaukee); 27 were performed in the axial plane and three, in the sagittal plane. The two sequences were performed with identical image locations, field of view, section

Abbreviations: SE

=

spin

FAT SAT

=

fat saturation,

echo.

2i3

thickness, and intersection gap. The axial images were obtained with a 7-mm section thickness and a 3-mm intersection gap, and the sagittal images were obtained with a 5-mm section thickness and a 2.5-mm

intersection

weighted all patients and

gap.

Routine

axial

intersection

matrix;

no phase

to 6 minutes

mean onds. either

26 seconds,

with

a

imaging time of 3 minutes 56 secA pelvic binder was not used with pulse sequence, and glucagon was

not administered

Image

prior

to imaging.

a double-echo

technique

was

SE T2-

weighted imaging, only the images obtamed with the second echo were used in this

study.

Films

quality 1 (n = 30) 2 (n = 30) (n

=

90)

of conventional

MR imaging interpretation. The reviewers were not blinded to the type of pulse se-

a comparison

of fast

SE images

using a relative three-point scale. The fast SE images were rated as better than, same as, or worse than conventional SE T2weighted images. The organ definition

214

Radiology

#{149}

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6

4 2

22

5

3

62

19

9

21

19

ii

0

17

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The pelvis: T2-weighted fast spin-echo MR imaging.

Fast spin-echo (SE) T2-weighted magnetic resonance (MR) imaging provides images with highly T2-weighted contrast in substantially reduced imaging time...
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