Image Acquisition
adni1
2004 – 2009
- Focused on consistent longitudinal structural imaging on 1.5T scanners using T1- and dual echoT2-weighted sequences.
- One-fourth of ADNI1 participants were also scanned using essentially the same protocol on 3T scanners.
adni1
1.5T Scanner
Participant Scan:
- 3 Plane Localizer
- Structural Sagittal T1
- Structural Sagittal T1
- REPEAT
- B1 Calibration – Head Coil (if applicable)
- B1 Calibration – Body Coil (if applicable)
- Axial PD/T2 Dual Echo
ADNIGO/2
2010 – 2016
- Imaging was performed at 3T with T1-weighted imaging parameters similar to ADNI1.
- In place of the dual echo T2-weighted image from ADNI1, 2D FLAIR and T2*-weighted imaging were added at all sites.
- Both fully sampled and accelerated T1-weighted images were acquired in each imaging session.
- Advanced imaging was included depending on scanner manufacturer:
- GE: diffusion (dMRI) imaging
- Philips: task-free resting state functional MRI (TF-fMRI)
- Siemens: arterial spin labeling (ASL) blood flow imaging.
ADNIGO/2
3T Scanner
Participant Scan:
- 3 Plane Localizer
- Structural Sagittal T1
- Accelerated Structural Sagittal T1
- rsfMRI (Philips systems only)
- Axial T2-FLAIR
- Axial T2-Star
- Axial ASL Perfusion (Siemens systems only)
- Axial DTI Scan (GE systems only)
ADNI3
2016-2022
- Imaging was captured exclusively on 3T scanners
- dMRI, TF-fMRI, and ASL were included on all participants in ADNI3 protocol with a few site-wise exceptions
- A two-tiered approach was created to accommodate the range of scanners for ADNI3: ‘ADNI3 Basic’ and ‘ADNI3 Advanced’ acquisitions were used for TF-fMRI and dMRI.
ADNI3
3T Scanner
Participant Scan:
- 3 Plane Localizer
- Accelerated Structural Sagittal T1
- Sagittal 3D FLAIR
- Axial T2 STAR
- Axial 2D/3D PASL
- Axial DTI
- Axial rsfMRI
- High Resolution Hippocampus Scan
ADNI4
2022 and beyond
- Exclusively done on 3T scanners with a limit to scan duration to one hour.
- MRI protocol allows for equivalent imaging sequences across vendor-platforms to maintain uniformity across all images captured for the study
- includes 3D T1, 3D FLAIR, 3D T2 GRE, T2, DTI, ASL, and TF-fMRI imaging sequences.
ADNI4
3T Scanner
Participant Scan:
- 3 Plane Localizer
- Accelerated Structural Sagittal T1
- Compressed Sensed Accelerated Structural Sagittal T1 (where applicable)
- Sagittal 3D FLAIR
- Sagittal 3D T2
- Axial 2D/3D ME T2 GRE
- DTI
- Axial DTI PA (MB if applicable)
- Axial DTI AP (MB if applicable)
- ASL
- 3D Multi-PLD pCASL
- 3D Multi-PLD PASL
- Axial rsfMRI (MB if applicable)
- High Resolution Hippocampus Scan
The types of scans collected from each phase of the study are listed below : Slice thickness increased to cover phantom.
Phantom Scans
The ADNI1 Protocol also included a phantom scan, with localizer and MP-RAGE scans available. For the phantom MP-RAGE scans, slice thickness was increased to cover the phantom.
Clinical Findings
Every participant scan undergoes a local clinical read by an on-site radiologist/clinician at the MRI facility. Scan interpretations for diagnostic clinical purposes will not be provided by the MRI Core for ADNI4. However, medical MR findings are recorded and available as part of the quality control done by the ADIR Lab. These findings include identification of infarctions, evidence of prior surgery or TBI, MPH/CSF dynamics disorders, cerebral microbleeds, superficial siderosis, and other vascular abnormalities such as DVAs and prior parenchymal hemorrhage. It should be noted that clinical findings may also be indicators of complications of therapy such as CMBs (ARIA-H), vasogenic edema (ARIA-E), or MPH-like effects on CSF dynamics.
Scanner Changes
MR scanners routinely undergo upgrades. These can be relatively minor (software version) or major (hardware changes, e.g., head coil). In some cases, the scanner itself will be replaced at an ADNI site. We advise the following approach to the issue of scanner changes:
1
Assume that longitudinal within participant data is not compatible before vs after a change in scanner.
2
Assume that longitudinal within participant data is not compatible before vs after a major hardware change (e.g., change in head coil).
3
Assume that longitudinal within participant data maybe compatible before vs after a sofware version change but be advised that this may not be shown to be true eventually for some types of software changes.
Nearly all technical scanner information is available through MRI image DICOM headers. Thus, users are encouraged to employ scan-level technical scanner information as filters in data collections as seen necessary.
Recommended Image Data: Which Scans to Select?
For researchers interested in the imaging process as a whole, imaging files are available at every stage of pre- and post-processing. However, most researchers will prefer to use the scans that have undergone the maximum level of correction. For ADNI1 and early ADNI2, the MPRAGE files that have undergone gradwarping, intensity correction, and have been scaled for gradient drift using phantom data are recommended for use. For all ADNI4 data, it is recommended to use the chosen scan selected during the QC process.
Scans from ADNI1 have standardized data sets that require additional information to us, please see the MRI Image Data page.
