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Low-grade glioma

Case Study
Prof. Jackson, Alan Manchester, University of Manchester United Kingdom

Patient history:

A 23-year-old male patient was referred to Hope Hospital, University of Manchester, for a MR-examination of the brain.

MR examination:

A routine brain examination consists of fast sequences in three orthogonal directions and with various contrast weightings. In case tumor pathology is found in one of these scans, additional sequences, like diffusion, perfusion and post-contrast scans, are performed.

 

The first sequence was a T2-weighted TSE sequence in the axial plane. High spatial resolution was obtained in short scan time (1:48 min). Next, a coronal T2-weighted FLAIR sequence was acquired. SENSE was used to reduce scan time (1:39 min). The third sequence of the routine brain examination was a T1-weighted Inversion Recovery sequence (5:02 min). Inversion delay time in this sequence is exactly half of the used repetition time. By doing so, optimal T1-weighted contrast is obtained while no negative magnetization is present. Modulus images are displayed.

 

In addition, a PRESTO_perfusion scan was acquired to visualize wash-in wash-out of a contrast bolus. Directly after this sequence, the T1-weighted inversion recovery sequence was repeated, in two orthogonal planes to detect possible contrast enhancement of the lesion.

 

Finally, a very fast single slice T2W_TSE sequence was acquired. This sequence was used to plan a multi-slice turbo spectroscopic imaging sequence with an echo time of 144 ms. In addition to spectroscopic imaging, a single voxel scan with short TE was also performed.

MR images and interpretation:

Axial T2W_TSE High spatial resolution in short scan time.coronal T2W_FLAIR SENSE is used to reduce scan time.Sagittal T1W_IR_TSE With TI exactly half of TR, modulus images show optimized T1-weighted contrast
Axial T2W_TSE
coronal T2W_FLAIR
Sagittal T1W_IR_TSE
High spatial resolution in short scan time.
SENSE is used to reduce scan time.
With TI exactly half of TR, modulus images show optimized T1-weighted contrast

 

The acquisition matrix in T2W-TSE is 400, generating high spatial resolution. As only 1 average is required, scan time remains below two minutes. A low-grade glioma is visible in the left hemisphere.

 

SENSE is used in the coronal T2W_FLAIR to reduce scan time. Full brain coverage is provided in less than 2 minutes.

 

Scan time of T1-weighted inversion recovery was longer, providing very high T1-weighting and thus very good anatomical detail. This scan can be used as post-contrast scan as well.

PRESTO_perfusion Full brain coverage. Dynamic scan time less than 1.5 seconds.Analysis on ViewForum Perfusion maps in color, and two intensity curves are displayed.sagittal T1W_IR_TSE Post-contrast scan. No contrast enhancement is visible
PRESTO_perfusion
Analysis on ViewForum
sagittal T1W_IR_TSE
Full brain coverage. Dynamic scan time less than 1.5 seconds.
Perfusion maps in color, and two intensity curves are displayed.
Post-contrast scan. No contrast enhancement is visible

 

Next, a PRESTO_perfusion sequence is acquired. It contains 35 slices of 3.0mm, providing full brain coverage. SENSE is used to reduce dynamic scan time, that is less than 1.5 seconds. Perfusion analysis is performed on ViewForum, providing perfusion maps in color. Two seeded ROI's are selected in the slice through the centre of the low-grade glioma. A signal-intensity curve is created from both ROI's. The signal drop due to susceptibility related changes during bolus-passage is similar for both ROI's in the lesion and the contra-lateral healthy side.

 

Two T1W-IR_TSE sequences in orthogonal directions were started directly after PRESTO_perfusion. No contrast enhancement is visible.

Single voxel spectroscopy Echo time 38 ms
Single voxel spectroscopy
Echo time 38 ms

 

The examination is concluded with two spectroscopy scans. First, turbo spectroscopic imaging is performed. The used echo spacing of 144 ms results in a spectral resolution of about 8 Hz, which is sufficient to separate the respective metabolite signals at 3.0T. With this fairly short TE, it is possible to use a TSE factor of 4, thereby reducing total scan time. The resulting metabolite maps give an overview of the metabolite distribution in a slice through the tumor.

 

Additionally a single voxel spectroscopy scan with short TE is acquired. The spectral resolution in this sequence is about 2 Hz, nicely separating the signals of the different metabolites that are present in a short-TE spectrum. NAA-level is low, some lactate is detected and ratio of choline/NAA and creatine/NAA are elevated.

Impact of Achieva 3.0T imaging:

Susceptibility effects are stronger at higher field strength. This is very advantageous for perfusion weighted imaging, where susceptibility effects caused by contrast bolus pasasage create the signal changes.

 

In spectroscopy, the signal-to-noise ratio and spectral resolution will increase with increasing field strength.

 

SpectroView post-processing allows for creation of color metabolite and ratio maps and spectral selection directly from a grid display in spectroscopic imaging. Automated peak fitting can be performed, generating tables of results.



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Nov 26, 2004

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Case Study
Achieva 3.0T
Release 1
Quasar Dual
Brain, Neuro
 

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