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Meningioma in the brain

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

Patient history:

A 63-year-old male presented with complaints of headache and dizzyness.

An MR-examination was performed in Hope Hospital, University of Manchester.

 

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. Next, a coronal T2-weighted FLAIR sequence was acquired. SENSE was used to reduce scan time.

 

The third sequence of the routine brain examination was a T1-weighted Inversion Recovery sequence. 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 fast diffusion tensor scan, providing six diffusion directions, was acquired. Subsequently, 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 T2W_TSE sequence was acquired in a slightly different axial plane. This sequence was used to plan a multi-slice turbo spectroscopic imaging sequence with an echo time of 144 ms.

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 one average is required, scan time remains below two minutes. A large heterogeneous lesion was visible in the right hemisphere.

 

SENSE was used in the coronal T2W_FLAIR to reduce scan time. Full brain coverage was 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.

 

Single shot diffusion tensor imaging b-value 800, low directional resolution.PRESTO_perfusion Full brain coverage, dynamic scan time less than 1.5 seconds.T1W_IR_TSE Post-contrast scan shows enhancement of the lesion.
Single shot diffusion tensor imaging
PRESTO_perfusion
T1W_IR_TSE
b-value 800, low directional resolution.
Full brain coverage, dynamic scan time less than 1.5 seconds.
Post-contrast scan shows enhancement of the lesion.

In addition to the routine brain procedure, single shot diffusion tensor imaging was performed. Six diffusion directions were acquired from which the FA maps were calculated. Fractional anisotropy is lower in the tumor as compared to the contra-lateral healthy side, as the normal structure of the brain is damaged.

 

Next, a PRESTO_perfusion sequence was acquired. It contains 35 slices of 3.0 mm, providing

full brain coverage. SENSE was used to reduce dynamic scan time, that is less than 1.5 seconds. The signal drop caused by susceptibility of the passing contrast bolus is larger in the lesion than in the contra-lateral healthy side, meaning that a high level of blood circulation is present.

Additional analysis can be performed on the console. Perfusion calculation maps will be presented in grayscale.

 

Two T1W-IR_TSE sequences in orthogonal directions were started directly after PRESTO_perfusion. Enhancement of the lesion is clearly visible.

 

Turbo spectroscopic imaging Comparison of two spectra from spectral grid
Turbo spectroscopic imaging
Comparison of two spectra from spectral grid

The final scan of the examination was a dual-slice turbo spectroscopic imaging sequence with an echo time of 144 ms. The maximum spectral resolution that can be obtained is limited by the echo spacing and is 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.

 

Metabolite maps and ratio maps were generated in SpectroView. As can be expected, the concentration of NAA is much lower in the lesion. This is clearly visible in the calculated NAA-map. The choline/creatine ratio in the lesion is higher compared to contra-lateral healthy side. This is caused by the nearly complete absence of creatine in the lesion, as can be seen in the separate spectra that were selected from the spectral grid. (left spectrum in lesion, right spectrum in contra-lateral healthy side)

 

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 passage 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.

 



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Jan 25, 2005

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

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