Achieva

Each patient underwent 3-Tesla MRI (Achieva; Philips Medical System, Best, the Netherlands) including diffusion-weighted imaging, conventional T1- and T2-weighted imaging, T2 fluid attenuated inversion recovery imaging, gradient echo imaging, 3D time-of-flight magnetic resonance angiography (MRA), and contrast enhanced MRA. Three-Tesla MRI (Achieva; Philips Medical System, Best, the Netherlands) was used to acquire 3D T1 turbo field echo MRI data with the following imaging parameters: sagittal slice thickness, 1.0 mm; over contiguous slices with 50% overlap; no gap; repetition time, 9.9 ms; echo time, 4.6 ms; flip angle, 8°; and matrix size of 240 × 240 pixels reconstructed to 480 × 480 over a field of view of 240 mm.

In this study, 7 patients underwent an MRI scan in a tertiary referral center after surgical removal of an intracochlear ILS or combined vestibulocochlear ILS and were included. Patients with a pure vestibular ILS were not included in this study. Initial surgery was performed between October 2017 and December 2019. MRI was performed on average 13.4 months after surgery. Four patients were implanted with a MED-EL SYNCHRONY implant (MED-EL, Innsbruck, Austria) with a diametrically magnetized internal magnet. In the other 3 cases, a Cochlear 512 Profile, a Cochlear 622 Profile Plus (Cochlear, Sydney, Australia ), and an Advanced Bionics (AB) 3D System (Advanced Bionics, Stäfa, Swiss), respectively, were implanted. In all cases, a single-stage surgery was performed.
In all cases, the implant magnet was intraoperatively determined and positioned 8–9 cm behind the external auditory canal [18 (link)].
MRI examinations were performed without a headband in the MED-EL SYNCHRONY, Cochlear 622, and AB 3D cases using the 3 T MRI unit (Achieva, Philips Medical Systems, Philips, Amsterdam, The Netherlands). A headband was used in the Cochlear 512 case. For this case a 1.5 T MRI unit (Achieva, Philips Medical Systems) was used.

In the training set, all patients underwent MRI on a 3.0-T MRI scanner (Achieva or Ingenia, Philips Medical Systems) with an 8-channel head coil. The preoperative MRI sequences included T1WI, T2, T1C, as well as ADC scans. After 5–6 min of administration of 0.1 mL/kg of gadolinium-based contrast material (Gadovist; Bayer), T1C were acquired.
In the external validation set, MRI exams were performed using a 3.0-T MRI scanner (Achieva, Philips Medical Systems) with an 8-channel head coil. Scaling and un-normalization of ADC pixel values generated at the scanner was performed as previously described^{55 (link)}. Constant level appearance (CLEAR) processing, a technique to achieve homogeneity correction by using coil sensitivity maps acquired in the reference scan, was performed^{55 (link)}. The acquisition protocols are described in further details in the Supplementary Table 1.

CMR was performed using a standardized protocol on 1.5-T magnetic resonance scanner with a 5-channel phased-array coil (in Chiba University Hospital: Achieva, Philips Medical Systems, Best, The Netherlands; in Chiba Emergency Medical Center: Avanto, Siemens Medical Solutions, Erlangen, Germany). Imaging consisted of cine (steady-state free precession images), T2-weighted (short-tau inversion recovery images) and LGE images (3-dimensional [Achieva, Philips Medical Systems] or 2-dimensional [Avanto, Siemens Medical Solutions] inversion recovery gradient echo images), and we obtained a LV 4-chamber view, a 2-chamber view, and a stack of short-axis views in each series during breath-holds gated to the electrocardiogram. Short-axis views were acquired from the atrioventricular ring through the LV at intervals of 8 mm thickness with 0 to 2 mm gap in cine images and 8–10 mm thickness with −5 to 2 mm gap in LGE images, and by three slices (at basal, mid and apex area) in T2-weighted images. The LGE images were acquired 10 to 15 min after intravenous administration of a gadolinium-based contrast agent (Magnevist, Schering AG, Berlin, Germany, or Meglumine Gadopentetate, Fuji Pharma, Toyama, Japan; 0.15 mmol/kg) in patients without contraindications of LGE.

The mpMRI examinations were performed with three 3.0-Tesla scanners (Achieva, Philips Healthcare; Discovery, GE Healthcare; Interia, Philips Healthcare) using a phased-array coil. The standard mpMRI protocol at our institution included a combination of T2WI, T1WI, DWI, and dynamic contrast-enhanced imaging. Details of the imaging parameters of the DWI sequence are summarized in Table 1.Table 1

Imaging protocols of the pelvis DWI sequences

Protocols	3.0 T Achieva(Philips Healthcare, the Netherlands)	3.0 T Discovery(Ge healthcare, Milwaukee, WI)	3.0 T Interia(Philips Healthcare, the Netherlands)
B-values (s/mm2)	0, 800	0, 800	0, 1000
TR/TE (ms)	3400/54	3000/60	4959/78
Imaging matrix	224 × 224	256 × 256	240 × 240
Field of view (mm2)	375 × 375	360 × 400	360 × 400
Slice thickness (mm)	6	8	7
Number of slices	24	25	28
Intersection gap	No	No	No

TR  Repetition time, TE Echo time

MR imaging was performed primarily with a 3.0-T MR scanner (Achieva or Ingenia, Philips Medical Systems, The Netherlands; or Skyra, Siemens Healthcare, Germany) or a 1.5-T MR scanner (Achieva; Philips), using an eight-channel head coil. The brain MR protocol with a spin-echo sequence included T1-weighted imaging (T1WI), T2-weighted imaging, fluid-attenuated inversion recovery imaging, and contrast-enhanced T1WI. The range of axial unenhanced T1-weighted fast spin echo images were obtained using the following parameters: repetition time (TR)/echo time (TE), 450–550 msec/7.3–11 msec; section thickness, 5–7 mm; field of view (FOV), 20–25 cm; and matrix, 200 × 256.
Contrast enhancement was achieved using gadoterate meglumine (Dotarem, Guerbet, Paris, France). A standardized single dose of 13 ml of MICA was exclusively applied in most adult patients for contrast-enhanced MR examination. For perfusion MR including dynamic susceptibility contrast imaging or dynamic-contrast enhanced imaging, a double injection of MICA was applied. The number of MICA administrations and the interval between the first and the last examinations were recorded. The mean interval between GBCA administrations was calculated by dividing the time (in days) between the first and last MRI examinations by the total number of examinations minus 1.