Source code for nighres.brain.mp2rage_skullstripping

import numpy as np
import nibabel as nb
import os
import sys
import nighresjava
from import load_volume, save_volume
from ..utils import _output_dir_4saving, _fname_4saving, \
                    _check_topology_lut_dir, _check_available_memory

[docs]def mp2rage_skullstripping(second_inversion, t1_weighted=None, t1_map=None, skip_zero_values=True, topology_lut_dir=None, save_data=False, overwrite=False, output_dir=None, file_name=None): """ MP2RAGE skull stripping Estimates a brain mask from MRI data acquired with the MP2RAGE sequence. At least a T1-weighted or a T1 map image is required Parameters ---------- second_inversion: niimg Second inversion image derived from MP2RAGE sequence t1_weighted: niimg T1-weighted image derived from MP2RAGE sequence (also referred to as "uniform" image) At least one of t1_weighted and t1_map is required t1_map: niimg Quantitative T1 map image derived from MP2RAGE sequence At least one of t1_weighted and t1_map is required skip_zero_values: bool Ignores voxels with zero value (default is True) topology_lut_dir: str, optional Path to directory in which topology files are stored (default is stored in TOPOLOGY_LUT_DIR) save_data: bool Save output data to file (default is False) overwrite: bool Overwrite existing results (default is False) output_dir: str, optional Path to desired output directory, will be created if it doesn't exist file_name: str, optional Desired base name for output files with file extension (suffixes will be added) Returns ---------- dict Dictionary collecting outputs under the following keys (suffix of output files in brackets) * brain_mask (niimg): Binary brain mask (_strip-mask) * inv2_masked (niimg): Masked second inversion imamge (_strip-inv2) * t1w_masked (niimg): Masked T1-weighted image (_strip-t1w) * t1map_masked (niimg): Masked T1 map (_strip-t1map) Notes ---------- Original Java module by Pierre-Louis Bazin. Details on the algorithm can be found in [1]_ and a presentation of the MP2RAGE sequence in [2]_ References ---------- .. [1] Bazin et al. (2014). A computational framework for ultra-high resolution cortical segmentation at 7 Tesla. DOI: 10.1016/j.neuroimage.2013.03.077 .. [2] Marques et al. (2010). MP2RAGE, a self bias-field corrected sequence for improved segmentation and T1-mapping at high field. DOI: 10.1016/j.neuroimage.2009.10.002 """ print('\nMP2RAGE Skull Stripping') # check topology lut dir and set default if not given topology_lut_dir = _check_topology_lut_dir(topology_lut_dir) # make sure that saving related parameters are correct if save_data: output_dir = _output_dir_4saving(output_dir, second_inversion) inv2_file = os.path.join(output_dir, _fname_4saving(module=__name__,file_name=file_name, rootfile=second_inversion, suffix='strip-inv2')) mask_file = os.path.join(output_dir, _fname_4saving(module=__name__,file_name=file_name, rootfile=second_inversion, suffix='strip-mask')) if t1_weighted is not None: t1w_file = os.path.join(output_dir, _fname_4saving(module=__name__,file_name=file_name, rootfile=t1_weighted, suffix='strip-t1w')) else: t1w_file = None if t1_map is not None: t1map_file = os.path.join(output_dir, _fname_4saving(module=__name__,file_name=file_name, rootfile=t1_map, suffix='strip-t1map')) else: t1map_file = None if overwrite is False \ and os.path.isfile(mask_file) \ and os.path.isfile(inv2_file) : print("skip computation (use existing results)") output = {'brain_mask': mask_file, 'inv2_masked': inv2_file} if t1w_file is not None: if os.path.isfile(t1w_file) : output['t1w_masked'] = t1w_file if t1map_file is not None: if os.path.isfile(t1map_file) : output['t1map_masked'] = t1map_file return output # start virtual machine, if not already running try: mem = _check_available_memory() nighresjava.initVM(initialheap=mem['init'], maxheap=mem['max']) except ValueError: pass # create skulltripping instance algo = nighresjava.BrainMp2rageSkullStripping() # get dimensions and resolution from second inversion image inv2_img = load_volume(second_inversion) inv2_data = inv2_img.get_data() inv2_affine = inv2_img.affine inv2_hdr = inv2_img.header resolution = [x.item() for x in inv2_hdr.get_zooms()] dimensions = inv2_data.shape algo.setDimensions(dimensions[0], dimensions[1], dimensions[2]) algo.setResolutions(resolution[0], resolution[1], resolution[2]) algo.setSecondInversionImage(nighresjava.JArray('float')( (inv2_data.flatten('F')).astype(float))) # pass other inputs if (t1_weighted is None and t1_map is None): raise ValueError('You must specify at least one of ' 't1_weighted and t1_map') if t1_weighted is not None: t1w_img = load_volume(t1_weighted) t1w_data = t1w_img.get_data() t1w_affine = t1w_img.affine t1w_hdr = t1w_img.header algo.setT1weightedImage(nighresjava.JArray('float')( (t1w_data.flatten('F')).astype(float))) if t1_map is not None: t1map_img = load_volume(t1_map) t1map_data = t1map_img.get_data() t1map_affine = t1map_img.affine t1map_hdr = t1map_img.header algo.setT1MapImage(nighresjava.JArray('float')( (t1map_data.flatten('F')).astype(float))) algo.setSkipZeroValues(skip_zero_values) algo.setTopologyLUTdirectory(topology_lut_dir) # execute skull stripping try: algo.execute() except: # if the Java module fails, reraise the error it throws print("\n The underlying Java code did not execute cleanly: ") print(sys.exc_info()[0]) raise return # collect outputs and potentially save inv2_masked_data = np.reshape(np.array( algo.getMaskedSecondInversionImage(), dtype=np.float32), dimensions, 'F') inv2_hdr['cal_max'] = np.nanmax(inv2_masked_data) inv2_masked = nb.Nifti1Image(inv2_masked_data, inv2_affine, inv2_hdr) mask_data = np.reshape(np.array(algo.getBrainMaskImage(), dtype=np.uint32), dimensions, 'F') inv2_hdr['cal_max'] = np.nanmax(mask_data) mask = nb.Nifti1Image(mask_data, inv2_affine, inv2_hdr) if save_data: save_volume(inv2_file, inv2_masked) save_volume(mask_file, mask) outputs = {'brain_mask': mask_file, 'inv2_masked': inv2_file} else: outputs = {'brain_mask': mask, 'inv2_masked': inv2_masked} if t1_weighted is not None: t1w_masked_data = np.reshape(np.array( algo.getMaskedT1weightedImage(), dtype=np.float32), dimensions, 'F') t1w_hdr['cal_max'] = np.nanmax(t1w_masked_data) t1w_masked = nb.Nifti1Image(t1w_masked_data, t1w_affine, t1w_hdr) if save_data: save_volume(t1w_file, t1w_masked) outputs['t1w_masked'] = t1w_file else: outputs['t1w_masked'] = t1w_masked if t1_map is not None: t1map_masked_data = np.reshape(np.array( algo.getMaskedT1MapImage(), dtype=np.float32), dimensions, 'F') t1map_hdr['cal_max'] = np.nanmax(t1map_masked_data) t1map_masked = nb.Nifti1Image(t1map_masked_data, t1map_affine, t1map_hdr) if save_data: save_volume(t1map_file, t1map_masked) outputs['t1map_masked'] = t1map_file else: outputs['t1map_masked'] = t1map_masked return outputs