Improved Detection of Target Metabolites in Brain Tumors with Intermediate TE, High SNR, and High Bandwidth Spin-Echo Sequence at 5T

Abstract

Background and purpose: Due to high chemical shift displacement, challenges emerge at ultra-high fields when measuring metabolites using ¹H-MRS. Our goal was to investigate how well the high SNR and high bandwidth spin-echo (HISE) technique perform at 5T for detecting target metabolites in brain tumors.

Materials and methods: Twenty-six subjects suspected of having brain tumors were enrolled. HISE and point-resolved spectroscopy (PRESS) single-voxel spectroscopy scans were collected with a 5T clinical scanner with an intermediate TE (TE = 144 ms). The main metabolites, including total NAA, Cr, and total Cho, were accessed and compared between HISE and PRESS using a paired Student t test, with full width at half maximum and SNR as covariates. The detection rate of specific metabolites, including lactate, alanine, and lipid, and subjective spectral quality were accessed and compared between HISE and PRESS.

Results: Twenty-three pathologically confirmed brain tumors were included. Only the full width at half maximum for total NAA was significantly lower with HISE than with PRESS (P < .05). HISE showed a significantly higher SNR for total NAA, Cr, and total Cho compared with PRESS (P < .05). Lactate was detected in 21 of the 23 cases using HISE, but in only 4 cases using PRESS. HISE detected alanine in 8 of 9 meningiomas, whereas PRESS detected alanine in just 3 meningiomas. PRESS found lipid in more cases than HISE, while HISE outperformed PRESS in terms of subjective spectral quality.

Conclusions: HISE outperformed the clinical standard PRESS technique in detecting target metabolites of brain tumors at 5T, particularly lactate and alanine.

FIG 1.

A comparison of CSDE with HISE and PRESS in a phantom containing 100% water. The red square indicates the FOV in the center of the phantom, while the middle image is the result of HISE, and the right image is the result of PRESS.

FIG 2.

A 43-year-old woman with a mass located in the left frontal lobe, suggesting a meningioma. It was an atypical meningioma (World Health Organization grade II) with invasion into the brain parenchyma. The HISE technique observed relatively strong Ala signal, while the PRESS technique could not differentiate between the Ala and Lac peaks. Both HISE and PRESS did not detect Lip signals. The yellow box in anatomical images represented the region of the volume of the SVS scan.

FIG 3.

A 67 -year-old woman with a mass in the left temporal lobe with surrounding edema. On the basis of multimodal MR imaging, a high-grade glioma was suspected. Clinical correlation was recommended. The glioma was classified as a glioblastoma (World Health Organization grade IV, IDH1 wild-type). In the HISE, a Lac signal was detected. In PRESS, due to chemical shift displacement effects, a Lip signal originating from the scalp was detected, and the Lac signal was covered by the Lip signal. The yellow box in anatomical images represented the region of the volume of the SVS scan.

FIG 4.

A 52-year-old man with a right occipital lobe space-occupying lesion, which was classified as a brain metastasis (originating from lung cancer). In the HISE, both Lac and Lip signals were detected. In PRESS, only a Lip signal was detected, and the Lac signal was covered by the Lip signal. The yellow box in anatomical images represented the region of the volume of the SVS scan.

FIG 5.

A 71-year-old woman with a space-occupying lesion in the right cerebellopontine angle, confirmed to be an acoustic neuroma after surgery. In the HISE, a small Lac signal was detected, In PRESS, the Lac signal was also covered by the Lip signal. The yellow box in anatomical images represented the region of the volume of the SVS scan.