High-resolution T2-weighted cervical cancer imaging: a feasibility study on ultra-high-field 7.0-T MRI with an endorectal monopole antenna

Abstract

ObjectivesWe studied the feasibility of high-resolution T2-weighted cervical cancer imaging on an ultra-high-field 7.0-T magnetic resonance imaging (MRI) system using an endorectal antenna of 4.7-mm thickness.MethodsA feasibility study on 20 stage IB1–IIB cervical cancer patients was conducted. All underwent pre-treatment 1.5-T MRI. At 7.0-T MRI, an external transmit/receive array with seven dipole antennae and a single endorectal monopole receive antenna were used. Discomfort levels were assessed. Following individualised phase-based B1 + shimming, T2-weighted turbo spin echo sequences were completed.ResultsPatients had stage IB1 (n = 9), IB2 (n = 4), IIA1 (n = 1) or IIB (n = 6) cervical cancer. Discomfort (ten-point scale) was minimal at placement and removal of the endorectal antenna with a median score of 1 (range, 0–5) and 0 (range, 0–2) respectively. Its use did not result in adverse events or pre-term session discontinuation. To demonstrate feasibility, T2-weighted acquisitions from 7.0-T MRI are presented in comparison to 1.5-T MRI. Artefacts on 7.0-T MRI were due to motion, locally destructive B1 interference, excessive B1 under the external antennae and SENSE reconstruction.ConclusionsHigh-resolution T2-weighted 7.0-T MRI of stage IB1–IIB cervical cancer is feasible. The addition of an endorectal antenna is well tolerated by patients.Key Points• High resolution T 2-weighted 7.0-T MRI of the inner female pelvis is challenging • We demonstrate a feasible approach for T 2-weighted 7.0-T MRI of cervical cancer • An endorectal monopole receive antenna is well tolerated by participants • The endorectal antenna did not lead to adverse events or session discontinuation Electronic supplementary materialThe online version of this article (doi:10.1007/s00330-016-4419-y) contains supplementary material, which is available to authorized users.

Proton MRS of cervical cancer at 7 T

“…We have found that the use of an internal antenna in combination with an external array of radiating antennas provides sufficient SNR for MRI and STEAM MRS acquisitions at 7 T. The inclusion of internal antennas to enhance SNR in MRI has been already explored at lower magnetic field strengths to image the uterine cervix, with positive results, 15,19,20 and has been validated in this pilot study at the field of 7 T. The positive effect of this internal monopole antenna has been recently investigated at our institution for the same patient population. 27 In particular, the quality of the T2w MRI obtained for all patients was found to be superior to the T2w MRI routinely acquired at 1.5 T. 27 The MRS results found in this study agree with previous published MRS studies at lower magnetic field strengths, where mainly fatty acid signals were observed in uterine cervical ACs. 11,[14][15][16][17][18]36 The fatty acid oxidation pathway in cancer cells has been recently given more attention and proven to be as important in cancer metabolism as the Warburg effect.…”

“…In vivo 1 H MRS of uterine cervical carcinomas at 7 T to measure fatty acid profiles has been shown to be feasible for the first time. We have found that the use of an internal antenna in combination with an external array of radiating antennas provides sufficient SNR for MRI and STEAM MRS acquisitions at 7 T. The inclusion of internal antennas to enhance SNR in MRI has been already explored at lower magnetic field strengths to image the uterine cervix, with positive results, and has been validated in this pilot study at the field of 7 T. The positive effect of this internal monopole antenna has been recently investigated at our institution for the same patient population . In particular, the quality of the T2w MRI obtained for all patients was found to be superior to the T2w MRI routinely acquired at 1.5 T …”

“…In the case of larger tumors, transvaginal coils may have a suboptimal performance. Endorectal monopole antennas have an improved far‐field performance and can cover larger regions …”

“…Endorectal monopole antennas have an improved far-field performance and can cover larger regions. [25][26][27] We propose to exploit the SNR available at 7 T in combination with an Rx internal antenna to explore the feasibility of tumor characterization in uterine cervix by the fatty acid profile measured with 1 H MRS.…”

Are We Heading to the Future of Musculoskeletal Tumor Imaging with Ultra-High Field 7T MRI?

“…Based on this case series, the present results clearly illustrated that UHF MRI outperformed conventional MRI in terms of malignancy characterization, diagnosis and local extension. Advantages of UHF MRI have been already documented in the oncological field, especially in prostate cancer, brain, oesophageal or cervical tumors [28][29][30][31][32][33][34]. Nonpathological imaging of bowel has shown increased spatial resolution and interestingly better signal of vessels in abdomen, which seems to be confirmed on our images with clear delineation of vessels anatomical layers [35,36].…”