Optimization of OE-MRI protocols and workflows to prepare for hypoxia mapping and quantification on an MR-linac
ID
Source
Brief title
Condition
- Miscellaneous and site unspecified neoplasms malignant and unspecified
Synonym
Research involving
Sponsors and support
Intervention
Outcome measures
Primary outcome
Optimization of the OE-MRI protocol and processing techniques required for
OE-MRI imaging on the MR Linac system based on signal to noise ratio, contrast
to noise and acquisition time. The study is successful when we arrive at
parameter settings resulting in geometrically accurate scans that have the
right contrast for the radiation oncologist to identify hypoxic regions.
Secondary outcome
not applicable
Background summary
The MR-Linac allows for the visualization of different MRI sequences, including
functional sequences that reflect tumour biological characteristics, such as
diffusion-weighted imaging (DWI) or dynamic contrast enhanced (DCE) MRI. This
is important as the field of radiation oncology is moving towards *biology
guided dose adaptation*; individualizing radiation dose based on biological
tumour response or tumour characteristics. The presence of hypoxia is one of
the most important biomarkers for the prediction of radiotherapy response, as
hypoxic cells are severely radioresistant. Oxygen enhanced (OE) MRI is a
promising technique to visualize hypoxia in vivo without the need for
radioactive tracers. This technique measures T1 relaxation time under two
conditions: with subjects breathing 21% O2 (room air) and with subjects
breathing 100% O2 (hyperoxic gas). T1 will significantly increase in normoxic
tissue, due to the ferromagnetic properties of the excess O2 that will resolve
in the interstitial tissue. In hypoxic tissue however, due to poorly oxygenated
haemoglobin, no/minimal excess O2 will resolve in the interstitial tissue, and
subsequently T1 will not change significantly. When combining OE-MRI signals
with DCE MRI (as a measure for perfusion) three regions can be identified: a
normoxic region (high signal changes on OE-MRI and DCE-MRI), hypoxic region (no
signal changes on OE-MRI, high signal changes on DCE-MRI) and a non-perfused
(necrotic) region (no signal changes on both OE-MRI and DCE-MRI). These signal
changes have been validated against tissue oxygen tension measures in several
tumour models. This MRI has several advantages compared to PET-tracer based or
invasive histological hypoxia measurements: it provides spatial information
about the distribution of hypoxia within a tumour and between primary tumours
and metastases; it gives the opportunity to perform longitudinal measurements
to study the evolution of hypoxia during treatment; it is non-invasive; it does
not burden patients with additional radioactive exposure; it is a low-cost
technique.
This technique has been tested on diagnostic MRI systems in head-and-neck
squamous cell carcinoma (HNSCC) and lung cancer patients in which it was shown
repeatable, accurate and able to detect radiotherapy-induced changes in
hypoxia[8-10]. Also, the technique was translated onto an MR Linac system and
shown reproducible results equivalent to diagnostic MRI systems.
However, whether OE MRI can be reproduced on other MR Linac systems remains to
be investigated. Also, hypoxia is an important biological mechanism for
radioresistance in several tumour sites, knowing HNSCC, lung cancer, prostate
cancer, cervical cancer, endometrial cancer, rectal cancer, pancreatic cancer,
renal cancer, anal cancer and bladder cancer. Whether the technique is
feasible, accurate and repeatable for these tumour types remains to be
investigated, and optimization of the dedicated scanning and image processing
protocols for the MR Linac is essential.
Study objective
Optimization of OE-MRI protocols and workflows to prepare for hypoxia mapping
and quantification on an MR-linac
Study design
Participants will undergo an MRI scan with a maximum duration of 90 minutes per
scan session. A maximum of 5 MRI scans per patient or volunteer can be
performed. Participants will be asked whether they also consent to the use of
MRI contrast agent and inhalation of hyperoxic gas (98-100% oxygen) with an
oxygen mask when necessary for the imaging.
Intervention
Participants will undergo an MRI scan with a maximum duration of 90 minutes per
scan session. A maximum of 5 MRI scans per patient or volunteer can be
performed. Participants will be asked whether they also consent to the use of
MRI contrast agent and inhala-tion of hyperoxic gas (98-100% oxygen) with an
oxygen mask when necessary for the im-aging.
Study burden and risks
No risks are known for healthy volunteers or patients undergoing MRI when they
are screened according to the MRI safety criteria. When patients are asked for
their consent for the administration of contrast agent their status will also
be reviewed for safety. Patients will be asked to participate in acquiring an
*oxygen-enhanced* MRI sequence, in which they will breath hyperoxic gas during
the scan (less than ten minutes). This is well tolerated by patients and does
not carry additional medical risks.
Heydenrijckstraat 70
Nijmegen 6521LR
NL
Heydenrijckstraat 70
Nijmegen 6521LR
NL
Listed location countries
Age
Inclusion criteria
- >= 18 years
- Capable and prepared to sign informed consent
- Healthy volunteers or cancer patients
Exclusion criteria
- Contraindication for MRI scanning as listed in screening form
- Neurological or psychiatric diagnosis making it impossible to remain fixed in
the same position during the whole examination.
- Refusal of subjects to be informed of chance findings possibly relevant to
their health
- In the case that study participation would interfere with regular treatment
- Renal function is unknown
- Renal function is below 30 ml/min
- Refusal of subjects for the use of an oxygen mask throughout the scanning
process
- Contra-indication for receiving hyperoxic gas (moderate-severe COPD, GOLD
stage 2-4).
Design
Recruitment
Medical products/devices used
Followed up by the following (possibly more current) registration
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In other registers
| Register | ID |
|---|---|
| CCMO | NL88931.091.25 |